Schiff's Diseases of the Liver (2 Volume Set) 10th ed

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Editors: C. Title:

Schiff, Eugene R.; Sorrell, Michael F.; Maddrey, Willis

Schiff's Diseases of the Liver, 10th Edition

Copyright ©2007 Lippincott Williams & Wilkins > Front of Book > Editors > Editors

Editors Eugene R. Schiff MD, FACP, FRCP, MACG Professor Department of Medicine, Chief, Division of Hepatology, Director, Center for Liver Diseases, University of Miami School of Medicine, Miami, Florida

Michael F. Sorrell MD, FACP Robert L. Grissom Professor Department of Medicine, University of Nebraska Medical Center, Omaha, Nebraska

Willis C. Maddrey MD, MACP, FRCP Executive Vice President for Clinical Affairs, Adelyn and Edmund M. Hoffman Distinguished Chair in Medical Science, Professor Department of Internal Medicine, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas

Secondary Editors Charles W. Mitchell Executive Editor Lisa Kairis Senior Managing Editor Angela Panetta Marketing Manager Bridgett Dougherty Project manager Benjamin Rivera Senior manufacturing Manager Doug Smock Creative Director Laserwords Private Limited, Chenni, India Compositor

RR Donnelley

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Printer

Contributing Authors Furqaan Ahmed MD Fellow Department of Medicine, Divison of Gastroenterology and Hepatology, Weill Medical College of Cornell University, New York, New York

Abdullah M. S. Al-Osaimi MD Assistant Professor Department of Internal Medicine, Division of Gastroenterology and Hepatology, University of Virginia Health System, Charlottesville, Virginia

Curtis K. Argo MD Fellow Department of Internal Medicine, Division of Gastroenterology and Hepatology, University of Virginia Health System, Charlottesville, Virginia

Miguel R. Arguedas MD, MPH Associate Professor Department of Medicine, Division of Gastroenterology and Hepatology, University of Alabama at Birmingham, Birmingham, Alabama

Vicente Arroyo MD Professor Department of Medicine, University of Barcelona; Director, Institute of Digestive and Metabolic Diseases, Hospital Clinic, Barcelona, Spain

Carmen Ayuso MD Professor Department of Radiology, University of Barcelona; Consultant, Department of Radiology, Barcelona Clínic Liver Cancer Group, Hospital Clínic, Barcelona, Spain

Bruce R. Bacon MD James F. King Endowed Chair in Gastroenterology; Professor Department of Internal Medicine; Director, Division of Gastroenterology and Hepatology, St. Louis University School of Medicine, St. Louis, Missouri

Yannick Bacq MD

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Praticien Hospitalier, Service d'Hépatogastroentérologie, Hôpital Trousseau, Tours, France

Matthias J. Bahr MD Associate Professor Department of Gastroenterology, Hepatology and Endocrinology, Medical School of Hannover, Hannover, Germany

Heike Bantel MD Assistant Professor Department of Gastroenterology, Hepatology and Endocrinology, Medical School of Hannover, Hannover, Germany

Alex S. Befeler MD Assistant Professor Department of Internal Medicine, University of Chicago, Pritzker School of Medicine, Chicago, Illinois

Paul D. Berk MD, FACP, FACG Professor Department of Medicine, Division of Digestive and Liver Diseases, Columbia University College of Physicians and Surgeons, New York, New York

Adrian M. Di Bisceglie MD, FACP Professor Department of Internal Medicine, St. Louis University; Chief of Hepatology, Division of Gastroenterology and Hepatology, St. Louis University Hospital, St. Louis, Missouri

Andrés T. Blei MD Professor Department of Medicine, Northwestern University, Chicago, Illinois

Joseph R. Bloomer MD Professor Director of Liver Center, Department of Medicine and Genetics, University of Alabama at Birmingham; Attending Physician, Department of Medicine, University of Alabama at Birmingham Hospital, Birmingham, Alabama

Jaime Bosch MD, PhD Professor

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Department of Medicine, University of Barcelona; Senior Consultant Hepatologist and Chief, Hepatic Hemodynamic Laboratory, Institute of Digestive Diseases and Metabolism Hospital Clinic, Barcelona, Spain

Jean F. Botha MD Assistant Professor Department of Surgery, University of Nebraska Medical Center, Omaha, Nebraska

Fernanda S. Branco MD Research Fellow Liver Unit, Barcelona Clínic Liver Cancer Group, Institute of Digestive Disease, Hospital Clinic, University of Barcelona, Barcelona, Spain

David A. Brenner MD Samuel Bard Professor and Chair Department of Medicine, Columbia University, College of Physicians and Surgeons, New York, New York

Robert S. Britton PhD Associate Research Professor Department of Internal Medicine, Division of Gastroenterology and Hepatology, St. Louis University School of Medicine, St. Louis, Missouri

Jordi Bruix MD, PhD Associate Professor Department of Medicine, University of Barcelona; Senior Consultant, Liver Unit, Barcelona Clínic Liver Cancer Group, Institut D'Investigacions Biomediques August, Pi i Sunyer, Hospital Clínic, Barcelona, Spain

Alan L. Buchman MD MSPH Associate Professor Department of Medicine, Division of Gastroenterology, Northwestern University Feinberg, School of Medicine, Chicago, Illinois

James R. Burton Jr. MD Assistant Professor Department of Medicine, Division Gastroenterology and Hepatology, University of Colorado at Denver and Health Sciences Center, Denver, Colorado

Stephen H. Caldwell MD

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Director of Hepatology Division of Gastroenterology and Hepatology, University of Virginia, Charlottesville, Virginia

Mical S. Campbell MD Instructor Department of Medicine, Division of Gastroenterology and Hepatology, University of Pennsylvania; Hepatologist, Penn Liver Transplant Center, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania

Andrés Cárdenas MD, MMSc Staff Member Institute of Digestive Diseases and Metabolism, University of Barcelona, Hospital Clínic, Barcelona, Spain

David L. Carr-Locke MD, FRCP, FASGE Associate Professor Department of Medicine, Harvard Medical School; Director of the Endoscopy Institute, Department of Gastroenterology, Brigham and Women's Hospital, Boston, Massachusetts

Cem Cengiz MD Staff Department of Gastroenterology, MESA Hospital, Ankara, Turkey

Shivakumar Chitturi MD Senior Lecturer Department of Gastroenterology and Hepatology, Australian National University Medical School; Staff Specialist, Department of Gastroenterology and Hepatology, The Canberra Hospital, Woden, Australia

Douglas M. Coldwell MD, PhD Professor Department of Interventional Radiology, University of Texas Southwestern Medical Center; Interventional Radiologist, Department of Radiology, Parkland Hospital, Dallas, Texas

Deirdre Coll MD Associate Professor Department of Radiology, Mount Sinai School of Medicine, New York, New York

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Hari S. Conjeevaram MD, MS Assistant Professor Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan

Juan Córdoba MD Hospital Vall d'Hebron, Universitat Autònoma de Barcelona, Barcelona, Spain

Gennaro D'Amico MD Chief Department of Gastroenterology, Ospedale V Cervello, Palermo, Italy

Srinivasan Dasarathy MD Assistant Professor Department of Medicine, Division of Gastroenterology and Hepatology, Cleveland Clinic Lerner College of Medicine, Cleveland Clinic, Cleveland, Ohio

Gary L. Davis MD Director Division of Hepatology, Baylor University Medical Center; Medical Director, Department of Liver Transplantation, Baylor Regional Transplant Institute, Dallas, Texas

Douglas T. Dieterich MD Professor Department of Medicine, Mount Sinai School of Medicine; Director, Continuing Medical Education, Department of Medicine, The Mount Sinai Medical Center, New York, New York

Bart L. Dolmatch MD Professor Department of Radiology, University of Texas Southwestern Medical Center; Chief, Department of Interventional Radiology, University of Texas Southwestern Medical Center, Dallas, Texas

Joanne M. Donovan MD, PhD Associate Clinical Professor Department of Medicine, Harvard Medical School; Staff Gastroenterologist, Division of Gastroenterology, Boston Veterans Affairs Medical Center, Boston, Massachusetts

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Reed E. Drews MD Associate Professor Department of Medicine, Harvard Medical School; Program Director, Hematology-Oncology Fellowship, Department of Medicine, Division of Hematology-Oncology, Beth Israel Deaconess Medical Center, Boston, Massachusetts

Michael A. Dunn MD, FACP Professor Department of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland; Chief Medical Officer, Windber Research Institute, Windber, Pennsylvania

Michael B. Fallon MD Professor Department of Medicine, University of Alabama at Birmingham; Director, Section of Hepatology, Chief, Gastroenterology and Hepatology, Birmingham Veterans Administration Medical Center, Birmingham, Alabama

Geoffrey C. Farrell MD, FRACP Professor Department of Hepatic Medicine, Australian National University; Director of Gastroenterology and Hepatology, The Canberra Hospital, Canberra, Australia

Thomas W. Faust MD Assistant Professor Department of Medicine, Division of Gastroenterology, University of Pennsylvania Health System, Philadelphia, Pennsylvania

Richard B. Freeman Jr. MD Professor Department of Surgery, Division of Transplantation, Tufts University School of Medicine; Staff Surgeon, Department of Surgery, Division of Transplantation, Tufts-New England Medical Center, Boston, Massachusetts

Lawrence S. Friedman MD Professor Department of Medicine, Harvard Medical School, Boston, Massachusetts; Chair, Department of Medicine, Newton-Wellesley Hospital, Newton, Massachusetts

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Scott L. Friedman MD Professor and Chief Department of Medicine, Division of Liver Diseases, Mount Sinai School of Medicine; Attending Physician and Chief, Department of Medicine, Division of Liver Diseases, Mount Sinai Hospital, New York, New York

Juan C. García-Pagán Consultant Hepatologist Hepatic Hemodynamic Laboratory Liver Unit, Institut de Malalties Digestives i Metabóliques, Hospital Clínic, Barcelona, Spain

Pere Ginès MD Associate Professor Facultad De Medicina, University of Barcelona; Chairman, Liver Unit, Hospital Clínic, Barcelona, Spain

Zachary D. Goodman MD, PhD Chairman Department of Hepatic and Gastrointestinal Pathology, Armed Forces Institute of Pathology, Washington DC

Stuart C. Gordon MD, FACP, FACG Clinical Associate Professor Department of Internal Medicine, Wayne State University School of Medicine; Director, Division of Hepatology, Henry Ford Health Systems, Detroit, Michigan

Gregory J. Gores MD Professor Department of Medicine and Physiology, Mayo Clinic College of Medicine, Rochester, Minnesota

Wendy J. Grant MD Assistant Professor Department of Surgery, University of Nebraska Medical Center, Omaha, Nebraska

Norton J. Greenberger MD Clinical Professor Department of Medicine, Harvard Medical School; Senior Physician, Department of Medicine-Gastroenterology, Brigham and Women's Hospital, Boston, Massachusetts

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J. Michael Henderson MD Professor Department of Surgery, Cleveland Clinic Lerner College of Medicine; Vice-Chairman, Division of Surgery, Cleveland Clinic, Cleveland, Ohio

Ira M. Jacobson MD Vincent Astor Professor of Clinical Medicine, Chief Division of Gastroenterology and Hepatology, Department of Medicine, Weill Medical College of Cornell University; Attending Physician, Department of Medicine, New York Presbyterian Hospital, New York, New York

Stephen P. James MD Director Division of Digestive Diseases and Nutrition, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland

Lennox J. Jeffers MD Professor Department of Medicine, Division of Hepatology, Center for Liver Diseases, University of Miami School of Medicine, Miami, Florida

Maureen M. Jonas MD Associate Professor Department of Pediatrics, Harvard Medical School; Associate in Gastroenterology, Department of Medicine, Children's Hospital Boston, Boston, Massachusetts

Marshall M. Kaplan MD Professor Department of Medicine, Tufts University School of Medicine; Chief Emeritus, Division of Gastroenterology, Tufts-New England Medical Center, Boston, Massachusetts

David Kershenobich MD, PhD Professor Department of Experimental Medicine, Laboratory of Liver, Pancreas and Motility, (HIPAM), Head, Faculty of Medicine, Universidad Nacional Autonoma de Mexico, Department of Experimental Medicine, Hospital General de Mexico, Mèxico City, Mexico

Mary T. Killackey MD Assistant Professor Department of Surgery, Tulane University; Attending Transplant

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Surgeon, Department of Surgery, Division of Transplant, Tulane University Hospital, New Orleans, Los Angeles

Samuel Klein MD William Dranforth Professor Department of Medicine and Nutrition Science, Director of Human Nutrition, Department of Internal Medicine, Washington University School of Medicine; Attending Physician, Department of Internal Medicine, Barres-Jewish Hospital, St. Loius, Missouri

Fred M. Konikoff MD Professor Department of Medicine, Director, Minerva Center for Gallstones and Lipid Metabolism in the Liver, Tel Aviv University, Tel Aviv, Israel; Head, Department of Gastroenterology and Hepatology, Meir Medical Center, Kfar Saba, Israel

Kevin Korenblatt MD Assistant Professor Department of Medicine, Division of Gastroenterology and Hepatology, Washington University School of Medicine, St. Loius, Missouri

Jelica Kurtovic MBBS, B Med Sci, FRACP Lecturer Faculty of Medicine, University of New South Wales; Staff Specialist, Gastrointestinal and Liver Unit, The Prince of Wales Hospital, Sydney, Australia

Richard Kwon MD Clinical Lecturer Division of Gastroenterology, University of Michigan Medical School, Ann Arbor, Minnesota

Nicholas F. LaRusso MD Professor Department of Internal Medicine, Mayo Clinic College of Medicine, Rochester, Minnesota

Konstantinos N. Lazaridis MD Assistant Professor Department of Internal Medicine, Mayo Clinic College of Medicine, Rochester, Minnesota

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Josh Levitsky MD Assistant Professor Department of Medicine, Division of Hepatology, Northwestern University Feinberg School of Medicine; Northwestern Memorial Hospital, Chicago, Illinois

James H. Lewis MD, FACP, FACG Professor Department of Medicine, Division of Gastroenterology, Georgetown University School of Medicine; Director of Hepatology, Georgetown University Hospital, Washington DC

Anna S. F. Lok MD Professor Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan

Willis C. Maddrey MD, MACP, FRCP Executive Vice President for Clinical Affairs Adelyn and Edmund M. Hoffman Distinguished Chair in Medical Science; Professor, Department of Internal Medicine, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas

Hala R. Makhlouf MD, PhD Research Associate Department of Hepatic and Gastrointestinal Pathology, Armed Forces Institute of Pathology, Washington DC; Professor, Department of Pathology, Faculty of Medicine, Ain Shams University, Cairo, Egypt

Harmeet Malhi MBBS Instructor Department of Medicine, Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota

Michael P. Manns MD Professor and Chairman Department of Gastroenterology, Hepatology, and Endocrinology, Medical School of Hannover, Hannover, Germany

James F. Markmann MD, PhD Assistant Professor Department of Surgery, Division of Transplant Surgery, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania

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Paul Martin MD Professor Department of Medicine, Mount Sinai School of Medicine; Associate Chief, Division of Liver Diseases, New York, New York

Timothy M. McCashland MD Medical Director of Liver Transplantation Department of Gastroenterology and Hepatology, University Nebraska Medical Center, Omaha, Nebraska

Arthur J. McCullough MD Chairman Department of Gastroenterology and Hepatology, Cleveland Clinic; Professor, Department of Medicine, Cleveland Clinic Lerner College of Medicine, Cleveland, Ohio

John G. McHutchison MD Professor Department of Medicine, Duke University Medical Center; Director, Department of Gastroenterologyl and Hepatology Research, Duke Clinical Research Institute, Durham, North Carolina

K. V. Narayanan Menon MD, FRCP (Edin), FRCP (Glasg) Assistant Professor Department of Medicine, Division of Gastroenterology and Hepatology, Mayo Clinic and Foundation, Rochester, Minnesota

Santiago J. Munoz MD, FACP, FACG Associate Professor Department of Medicine, Jefferson Medical College; Chief, Division of Hepatology, Medical Director, Liver Transplant Program; Director, Center for Liver Disease, Departments of Surgery and Medicine, Albert Einstein Medical Center, Philadelphia, Pennsylvania

Miguel Navasa MD Associate Professor Department of Medicine, University of Barcelona, Institute of Digestive Diseases, Hospital Clínic, Barcelona, Spain

Francesco Negro MD Adjoint Agrege, Departments of Internal Medicine, and Clinical Pathology, University Hospital, Geneva, Switzerland

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Marco A. Olivera-Martínez MD Professor Department of Medicine, Universidad Panamericana, Medical Director, Liver Transplant Program, Instituto Nacional de Ciencias Médicas y Nutrición, Mexico City, Mexico

Kim M. Olthoff MD Associate Professor Department of Surgery, University of Pennsylvania; Director, Liver Transplant Program, University of Pennsylvania, Philadelphia, Pennsylvania

James S. Park MD Fellow Department of Medicine, Division of Gastroenterology, Hepatology and Nutrition, University of Pittsburg Medical Center, Pittsburgh, Philadelphia

Antonio R. Perez-Atayde MD Associate Professor Department of Pathology, Children's Hospital, Harvard Medical School, Boston, Massachusetts

David H. Perlmutter MD Professor and Chair Department of Pediatrics, University of Pittsburgh School of Medicine; Physician-in-Chief and Scientific Director, Children's Hospital of Pittsburgh, Pittsburgh, Philadelphia

Daniel S. Pratt MD Assistant Professor Department of Medicine, Harvard Medical School; Executive Director, Liver, Biliary, Pancreas Center, Massachusetts General Hospital, Boston, Massachusetts

K. Rajender Reddy Professor Department of Medicine and Surgery, Division of Hepatology, University of Pennsylvania; Director of Hepatology, Medical Director of Liver Transplantation, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania

Arie Regev MD Associate Professor

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Department of Medicine, Division of Hepatology, University of Miami Leonard M. Miller, School of Medicine, Miami, Florida

Stephen M. Riordan MD, FRACP, FRCP Associate Professor Faculty of Medicine, University of New South Wales; Senior Staff Specialist and Director, Gastrointestinal and Liver Unit, The Prince of Wales Hospital, Sydney, Australia

Juan Rodés MD FRCP Professor Facultad de Medicina, University of Barcelona; Director General, Hospital Clínic, Barcelona, Spain

Hugo R. Rosen Waterman Professor of Medicine, Head Division of Gastroenterology and Hepatology, University of Colorado at Denver and Health Sciences Center, Denver, Colorado

Mark A. Rosen MD, PhD Assistant Professor Department of Radiology, University of Pennsylvania Health System, Philadelphia, Pennsylvania

Andrew S. Ross MD Clinical Instructor Department of Medicine, Section of Gastroenterology, The University of Chicago Hospitals, Chicago, Illinois

Neeraj Saraf MD Consultant Division of Hepatology, Global Hospital, Hyderabad, India

Eugene R. Schiff MD, FACP, FRCP, MACG Professor Department of Medicine, Chief, Division of Hepatology, Director, Center for Liver Diseases, University of Miami School of Medicine, Miami, Florida

Michael L. Schilsky MD Associate Professor Department of Medicine, Weill Medical College of Cornell University; Medical Director, Center for Liver Disease and Transplantation, New

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York Weill Cornell Medical Center, New York, New York

Byers W. Shaw Jr. MD, FACS Merle M. Musselman Professor and Chair Department of Surgery, University of Nebraska Medical Center, Omaha, Nebraska

Mitchell L. Shiffman MD Professor Department of Medicine, Chief of Hepatology Section, Medical Director of the Liver Transplant Program, Virginia Commonwealth University Medical Center, Richmond, Virginia

Maria H. Sjögren MD, MPH Associate Professor Department of Preventive Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland; Director of Hepatology Research, Gastroenterology Service, Department of Medicine, Walter Reed Army Medical Center, Washington DC

Michael F. Sorrell MD Robert L. Grissom Professor of Medicine University of Nebraska Medical Center, Section of Gastroenterology, Nebraska Medical Center, Omaha, Nebraska

Debra L. Sudan MD Professor Department of Transplant Surgery, University of Nebraska Medical Center; Surgeon, Department of Transplant Surgery, Nebraska Medical Center, Omaha, Nebraska

Anthony S. Tavill MD Professor Department of Medicine and Nutrition, Case Western Reserve University School of Medicine; Consultant Hepatologist, The Cleveland Clinic Foundation; Mathile and Morton Stone Chair, Department of Digestive and Liver Disorders, Metro Health Medical Center, Cleveland, Ohio

Tram T. Tran MD Assistant Professor Department of Medicine, David Geffen School of Medicine, University of California; Medical Director, Liver Transplant, Comprehensive Transplant Center, Cedars Sinai Medical Center, Los Angeles, California

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Ian R. Wanless MD, CM, FRCPC Professor Department of Pathology, Dalhousie University, Nova Scotia, Canada

Paul B. Watkins MD Verne S. Caviness Distinguished Professor Department of Medicine, University of North Carolina; Director, General Clinical Research Center, University of North Carolina Medical Center, Chapel Hill, North Carolina

Russell H. Wiesner MD Medical Director Liver Transplantation, Mayo Clinic Transplant Center, Rochester, Minnesota

Roger Williams CBE, MD, FRCP, FRCS, FRCPE, FRACP, FMedSci, FRCPI (Hon), FACP (Hon) Director UCL Institute of Hepatology, Royal Free and University College Medical School; Honorary Consultant Physician, Department of Hepatology, University College London Hospitals, London, United Kingdom

Allan W. Wolkoff MD Professor Department of Medicine and Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, New York

Amany Zekry MD, PhD, FRACP Senior Lecturer Department of Medicine, University of New South Wales; Director of Hepatology, St. George Hospital, Kogarah, Sydney

Jeffrey I. Zwicker MD Instructor Department of Medicine, Division of Hematology-Oncology, Harvard Medical School, Beth Israel Deaconess Medical Center, Boston, Massachusetts

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Editors: C. Title:



Copyright ©2007 Lippincott Williams & Wilkins > Front of Book > Dedication

Dedication We dedicate this tenth edition of Diseases of the Liver to Telfer B. Reynolds, who was a great teacher, mentor, clinician and contributor to the science and practice of hepatology. Furthermore, we dedicate this edition to our wives Dana, Shirley and Ann for their continuing support of our endeavors.

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Copyright ©2007 Lippincott Williams & Wilkins > Front of Book > Preface to the First Edition

Preface to the First Edition In the recent words of Himsworth, the present time seems to be particularly opportune for reviewing our knowledge of liver disease. A partial list of reasons would include the advances made in the fundamental sciences as they pertain to liver structure and function; the advances in the experimental approach to liver disease; the increased knowledge in the field of viral hepatitis; the newer clinical criteria and concept of hepatic coma, with attention focused on disturbance in the metabolism of ammonia; a better understanding of the pathogenesis and the treatment of cirrhosis; a clearer concept of the metabolic defect in hemochromatosis and the apparent effectiveness of depleting iron stores in the treatment of this disorder; the implication of disturbed copper metabolism in hepatolenticular degeneration; the increasing experience with needle biopsy of the liver; and the surgical attack on portal hypertension. This book is not intended to be encyclopedic in nature but rather the expression of present-day information pertaining to various aspects of liver disease by a group of authors particularly qualified by their experience, interest, and scientific contributions. The reader may discover certain omissions, but he usually will find these to be matters of lesser importance. He will be more than compensated by the quality of the information contained, which deals with those aspects of hepatic disease that are much more apt to concern him, including the description of the principles of treatment, both medical and surgical, by experts in the field. Furthermore, he will frequently find it unnecessary to consult other books, particularly on points dealing with basic concepts. To various contributors the editor expresses his deep gratitude for their excellent and willing cooperation. He has considered it good fortune indeed to have been associated with them in this undertaking. He wishes to express his thanks to Cecil J. Waston, Arthur J. Patek, Jr., and to his colleague, Edward A. Gall, for their helpful suggestions. Leon Schiff

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Copyright ©2007 Lippincott Williams & Wilkins > Front of Book > Preface

Preface The editors trust that this 10th edition of Diseases of the Liver provides an accurate assessment of the many states of the art in hepatology. The platform on which hepatology is based has never been sturdier. The depth of understanding of many processes that take place in the liver and the multiple factors that affect them give us hope that ever more successful ways to diagnose and treat a variety of liver disorders is in the offing. The clinical patterns and natural history of many liver diseases are now quite well described. The complex interactions that affect the course the individual patient with a liver disorder might follow are being assessed and to an ever-increasing extent understood. The 10th edition is introduced by a presentation of an approach to the evaluation of the patient with known or suspected liver disease utilizing history, physical examination, and widely available biochemical, serologic, and imaging studies. The 10th edition ends with a series of chapters on the present status of liver replacement. In between are remarkable chronicles of progress and the posing of questions yet to be answered. The foundations of hepatology based on clinical chemistry, imaging, and the power of properly interpreted liver biopsies are well described. Considerable attention is paid to the hepatitis viruses and the consequences of infections with each. For hepatitis C, diagnostic and assessment methods are well established. The remarkable emergence of the story of hepatitis C is well told and embroidered in several chapters. The importance of hepatitis C genotype and the level of HCV RNA on outcome and likelihood of treatment success is emphasized. The ability to treat chronic hepatitis C has improved greatly during the last decade and new antiviral and immunomodulatory approaches are likely to emerge in the near future. What is missing for hepatitis C is an effective vaccine. The complex interactions between hepatitis C and other viruses have been recognized and the apparent synergistic effect of hepatic injury from hepatitis C and alcohol on fibrosis is an area receiving great attention. Furthermore, interest in hepatitis B has never been higher. For hepatitis B, there are effective vaccines that have proved to be life

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changing in areas of the world where programs that ensure availability and utilization of vaccines have been successful. However, there are millions of patients already infected with hepatitis B and many are destined to succumb to the complications of cirrhosis or hepatocellular carcinoma unless further progress in therapeutic development occurs. The importation of ideas from basic science and many disciplines and clinical lessons learned from other specialties are apparent throughout the book. One area of interest clearly influences another. The role of viruses and the response to the presence of the viruses in the development of hepatocellular carcinoma is a fascinating field. There has been a veritable explosion of the number of cases of hepatocellular carcinoma, especially those related to hepatitis C over the last few years. The ability of an individual to favorably respond to an environmental insult (be it a virus or a chemical) is attracting considerable interest. In drug-induced liver disease, early (innate) responses may well determine whether a patient has a transient perturbation in the liver or develops a devastating illness. Then there is the focus on the many roles and consequences of fat in the liver. Once considered benign, fat deposition in the liver is now viewed as a potential cause of cirrhosis and even a precursor of hepatocellular carcinoma. The stories of the interactions of fat and fibrosis have overtones of genetic influences, as well as associations with other disorders grouped as the metabolic syndrome, which are clearly of growing importance. The ever-increasing importance of liver transplantation is recognized in this edition, with a separate section devoted to topics of importance to the clinician caring for patients before and after liver transplantation. We have fashioned a book within a book regarding liver transplantation and trust this section will provide a comprehensive resource without the necessity to refer to more specialized references sources. There is much more to be discovered and assimilated about the liver in the near future. Ways to modulate gene expression, understand (and even regulate) the many roles of nuclear receptors, the interactions of cytokines and hepatic growth factors, and the roles of metals and minerals— all these and many more areas are discussed in the 10th edition. The editors and the authors are pleased to present this 10th edition. Differences are being made that will be life changing for patients with liver diseases. These are the best of times for those interested in the liver. Eugene R. Schiff Michael F. Sorrell

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Willis C. Maddrey

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Copyright ©2007 Lippincott Williams & Wilkins > Table of Contents > Volume I > Section I - Overview: Clinical Fundamentals of Hepatology > Chapter 1 - History Taking and Physical Examination for the Patient with Liver Disease

Chapter 1 History Taking and Physical Examination for the Patient with Liver Disease Norton J. Greenberger

Key Concepts z

In the care of patients with jaundice, a careful history, physical examination, and review of standard laboratory tests should allow a physician to make an accurate diagnosis in 85% of the cases.

z

The triad of findings of splenomegaly, ascites, and an increased number of venous collateral vessels on the anterior abdominal wall indicates a diagnosis of portal hypertension.

z

The presence of two physical findings (ascites and evidence of portal-systemic encephalopathy [asterixis]) and two laboratory findings (hypoalbuminemia [3 seconds]) indicates a diagnosis of cirrhosis of the liver.

z

Three physical findings (parotid enlargement, gynecomastia, and Dupuytren's contracture) indicate that a patient is almost certainly consuming excessive amounts of alcohol.

z

In adult patients with a new onset of jaundice, eight disorders account for 98% of the ultimately established diagnoses. They include viral hepatitis, alcohol-induced liver disease, chronic hepatitis (all causes), drug-induced liver disease, gallstones and their complications, carcinoma of the pancreas, primary biliary cirrhosis, and primary sclerosing cholangitis. By the time patients with metastatic liver disease have jaundice, the diagnosis should be obvious because the liver has been extensively replaced by tumor.

Jaundice is a common presentation among patients with liver and biliary

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tract disease. The terms jaundice and icterus are used to designate skin and eyes appearing yellow resulting from the retention and deposition of biliary pigments (biliary monoglucuronides and diglucuronides). Although bilirubin stains all tissue, jaundice is most evident in the sclerae, face, and trunk. Jaundice is most commonly caused by parenchymal liver diseases such as viral hepatitis or cirrhosis, obstruction of the extrahepatic biliary tree as in choledocholithiasis and carcinoma of the pancreas, and less commonly, disorders associated with brisk hemolysis such as sickle cell anemia. The late Franz Ingelfinger stated in 1958 that the cause of jaundice can be identified in approximately 85% of patients after a careful study of the history and the performance of a physical examination and review of standard laboratory data. The same applies today. Table 1.1 lists the general and specific questions to ask in relation to the specific causes of liver and biliary tract disease.

History Taking for the Patient with Jaundice or Abnormal Results of Liver Tests Anorexia is a cardinal symptom of viral hepatitis and of neoplasms involving the liver, colon, biliary tree, or pancreas. Weight loss of more than 10 pounds P.4 (4.5 kg) should always raise the question of a neoplastic disorder.

Table 1.1. Specific Questions to Ask Patients with Jaundice or Liver Disease

RELATED TO VIRAL HEPATITIS Blood transfusions (especially if before 1990) Intravenous drug use Sexual practices Anal-receptive intercourse Sex with a prostitute History of sexually transmitted disease Multiple sexual partners (>5/y) Intercourse with individuals with hepatitis B or C Contact with individuals with jaundice Changes in taste and smell Needlestick exposure Work in renal dialysis units Surgeons in trauma units or operating rooms exposed to users of intravenous drugs Shared razors or toothbrushes Body piercing (ears, nose)

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Tattoos Intranasal cocaine use SPECIAL RISK FACTORS FOR HEPATITIS A Travel to endemic areas Ingestion of raw shellfish (harvested from contaminated waters) Exposure to patients in places where clusters of hepatitis may occur (e.g., institutions, restaurants, preschool nurseries) MEDICATION RELATED Review all prescription medications Ask specifically about all over-the-counter drugs Ask specifically about vitamins (especially vitamin A) Ask specifically about any foods, herbal preparations, home remedies purchased in a health food store ALCOHOL USE Obtain detailed quantitative history of both recent and previous alcohol use from the patient and family members Question whether patient has experienced withdrawal symptoms, driving-under-the-influence convictions CAGE (cut down, annoyed, guilty, eye opener) criteria (see text) Check for evidence of alcohol-associated illnesses (pancreatitis, peripheral neuropathy) MISCELLANEOUS QUESTIONS Pruritus (suggests cholestasis either intrahepatic or extrahepatic) Evolution of jaundice (dark urine, light stools) Recent changes in menstrual cycle (amenorrhea suggests chronic liver disease, often cirrhosis) History of anemia, sickle cell disease, known hemoglobinopathy, artificial heart valves Symptoms suggestive of biliary colic, chronic cholecystitis Family history of liver or gallbladder disease History of inflammatory bowel disease (should raise the question of primary sclerosing cholangitis and receipt, if any, of blood transfusions) Occupational history and, specifically, exposure to hepatotoxins

Chills and fever along with headache and myalgia should raise the question of viral hepatitis, especially type A. Chills and fever along with right upper quadrant abdominal pain suggest a diagnosis of biliary tract disease, especially choledocholithiasis and ascending cholangitis. Arthritis can be the harbinger of viral hepatitis, autoimmune chronic

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hepatitis, inflammatory bowel disease with underlying liver disease, primary sclerosing cholangitis, or granulomatous disorders such as sarcoidosis. Fleeting skin lesions are often present in patients with viral hepatitis B. Excoriations, indicating pruritus, should raise the question of either intrahepatic or extrahepatic cholestasis, particularly primary biliary cirrhosis or primary sclerosing cholangitis. With regard to abdominal pain, the standard questions to ask concern the location, character, radiation, factors precipitating or relieving pain, and whether there are other systemic symptoms that accompany the pain. Patients should be asked to compare current abdominal discomfort with other causes of abdominal pain that they have experienced in the past (e.g., gastroesophageal reflux symptoms, non–ulcer-type dyspepsia). Questions to be asked in relation to viral hepatitis include specific questions about blood transfusions, especially whether they were received before 1990. P.5 The date is important because before that time no serologic tests were available for the detection of infection with hepatitis C virus. Intravenous drug use is currently the most common cause of hepatitis C. It is important to ask specifically about sexual practices, especially high-risk sexual behavior. In this regard, anal-receptive intercourse is known to be a significant risk factor for hepatitis B. Sexual practices associated with an increased risk of hepatitis C include a history of sexual relations with a prostitute, history of a sexually transmitted disease, and multiple sexual partners per year. In addition, intercourse with patients known to be positive for hepatitis B and C (e.g., spouses) is known to be a risk factor for contracting these forms of hepatitis. Contact with jaundiced individuals may be a risk factor for hepatitis A and B. Changes in taste and smell occur fairly frequently in patients with hepatitis, especially viral hepatitis A. They contribute, in a large part, to the anorexia experienced by such patients. This is in part due to a decreased sense of smell (hyposmia), perception of unpleasant smells from foods that are not ordinarily perceived as unpleasant (dysosmia), a decreased sense of taste (hypogeusia), and perception of unpleasant taste (dysgeusia). Hypogeusia is often reflected by the fact that patients may spontaneously state that they have lost their taste for cigarettes. Health care professionals are at risk of contracting hepatitis C. This can occur through needlestick exposure, by working in renal dialysis units, and in trauma units, emergency departments, or operating rooms through surgical procedures on patients harboring the hepatitis C virus in whom that diagnosis is not immediately apparent. All users of intravenous drugs should be suspected of harboring the hepatitis C virus. Special risk factors for hepatitis C include tattoos, body piercing (e.g., of the ears and nose), history of snorting cocaine, and use of

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shared razors or toothbrushes. Special risk factors for hepatitis A include travel to endemic areas such as Mexico and Latin America and the African subcontinent, ingestion of raw shellfish that may have been harvested from contaminated waters, and exposure to patients in places where clusters of hepatitis may occur. The latter has been well documented in mental institutions, restaurants, preschool nurseries, and close living quarters. Hepatitis A can be transmitted parenterally because there is brief viremia. Medication use, including all prescription drugs and all over-the-counter drugs, should be carefully reviewed. The constellation of clinical features that include fever, arthritis or arthralgia, rash, and eosinophilia in a patient with jaundice or abnormal results of liver tests should always raise the question of medication-induced liver disease. This can be recalled by the mnemonic FARE, which stands for fever, arthritis, rash, and eosinophilia. The patient should be asked specifically about intake of vitamins, especially vitamin A, and about any foods, herbal preparations, or home remedies purchased in health food stores. Several herbal preparations have been found to be hepatotoxic. Detailed quantitative information should be obtained from both the patient and family members about recent and previous alcohol use. For reference purposes, 1 ounce (30 mL) of bourbon whiskey contains 10 to 11 g of alcohol, as does one 12-ounce (360 mL) container of beer or 4 ounces (120 mL) of red table wine. Each one of these can be considered as 1 unit. Ingestion of more than 3 units/day everyday or more than 21 units/week is excessive, especially for women. The threshold for alcohol-induced hepatic injury appears to be 30 g/day for women and 60 g/day for men if ingested over 5 to 10 years. These numbers may have to be modified if additional risk factors for liver disease are present (e.g., hepatitis C). One also needs to determine whether the patient has experienced withdrawal symptoms. The CAGE criteria are reliable indicators of excessive alcohol use. The CAGE criteria relate to the following four questions: 1. Has the patient tried to cut back on alcohol use? 2. Does the patient become angry when asked about his or her alcohol intake? 3. Does the patient feel guilty about his or her alcohol use? 4. Does the patient need an eye opener in the morning? In this regard, many patients with chronic alcoholism experience morning nausea and dry heaves. The examiner should check for evidence of alcohol-associated illnesses (e.g., pancreatitis and

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peripheral neuropathy). A history of pruritus suggests cholestasis, either intrahepatic or extrahepatic. Table 1.2 shows the differential diagnosis. The patient should be specifically asked about the evolution of jaundice (i.e., the onset of dark urine and light stools), which may provide clues to the duration of illness. Recent changes in the menstrual cycle, particularly amenorrhea, if present, suggests chronic liver disease and often cirrhosis. A history of anemia, sickle cell disease, and hemoglobinopathy should also be ascertained for African-American patients. Right upper quadrant abdominal pain should prompt detailed questions about whether such pain is consistent with biliary colic or chronic cholecystitis. A history of inflammatory bowel disease should raise the question of primary sclerosing cholangitis or, if the patient has received blood transfusions in the past, hepatitis C. An occupational history should be obtained and questions about specific exposure to a known or suspected hepatotoxin should be asked of industrial workers with jaundice or liver disease.

Table 1.2. Differential Diagnosis of Jaundice

MOST COMMON CAUSES Viral hepatitis Alcoholic liver disease Cholecystitis, choledocholithiasis Carcinoma of the pancreas COMMON CAUSES Drug- or toxin-induced liver disease Chronic hepatitis Sickle cell anemia Sepsis Postoperative state Primary biliary cirrhosis Primary sclerosing cholangitis LESS COMMON CAUSES Hodgkin's disease, non-Hodgkin's lymphoma Total parenteral nutrition Gilbert's syndrome (unconjugated hyperbilirubinemia rarely exceeds 3.0 mg/dL and detectable jaundice is infrequent) Metastatic liver disease (jaundice does not develop until >85%–90% of the liver is replaced by tumor) CAUSES AND PRESUMED SITES OF INTRAHEPATIC CHOLESTASIS Liver cell (hepatocellular) Viral hepatitis

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Alcoholic liver disease Chronic active liver disease α 1 -Antitrypsin deficiency Hepatocanalicular Drugs (androgens, phenothiazines) Sepsis Postoperative state Total parenteral nutrition Hodgkin's and non-Hodgkin's lymphoma Amyloidosis Sickle cell anemia Toxic shock syndrome Ductular Sarcoidosis Primary biliary cirrhosis Bile ducts Intrahepatic biliary atresia Caroli's disease Cholangiocarcinoma Primary sclerosing cholangitis Recurrent cholestasis Benign recurrent intrahepatic cholestasis Recurrent jaundice of pregnancy Dubin-Johnson syndrome

P.6

Physical Examination of the Patient with Jaundice or Abnormal Results of Liver Tests The key elements in the physical examination of a patient with jaundice or abnormal results of liver tests are summarized in Table 1.3. Several important clues are evident on general inspection of the patient. It should be determined whether scleral icterus is present, and this should be done in natural daylight. Scleral icterus can usually be detected if the serum bilirubin level is elevated to values greater than 3.0 mg/dL. The presence of pallor suggests anemia. Wasting suggests advanced chronic liver disease or a neoplastic disorder. Needle tracks or evidence of skin popping suggest intravenous drug abuse. The presence of skin excoriation confirms that the patient has been experiencing pruritus, which can be particularly severe among patients with primary biliary cirrhosis and primary sclerosing cholangitis. The one area where such patients cannot scratch is the interscapular area, and this is usually free of evidence of excoriation. The presence of ecchymosis or petechiae raises the question of clotting problems, especially

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thrombocytopenia. P.7 Muscle tenderness and weakness are not uncommon among patients with chronic alcoholism and alcoholic myopathy. These findings are often overlooked. When associated with severe acute pancreatitis, discoloration of the abdomen is termed the Grey Turner's sign. This finding implies increased likelihood of death. Other less common causes of ecchymosis include rhabdomyolysis, muscle infarction, mesentery thrombosis, strangulated bowel with extensive intestinal infarction, and massive intraperitoneal bleeding.

Table 1.3. Physical Examination of the Patient with Jaundice

GENERAL INSPECTION Scleral icterus Pallor Wasting Needle tracks Evidence of skin excoriations Ecchymosis or petechiae Muscle tenderness and weakness Lymphadenopathy Evidence of pneumonia Evidence of congestive heart failure PERIPHERAL STIGMATA OF LIVER DISEASE Spider angiomata Palmar erythema Gynecomastia a Dupuytren's contracture a Parotid enlargement a Testicular atrophy Paucity of axillary and pubic hair Eye signs mimicking hyperthyroidism ABDOMINAL EXAMINATION Hepatomegaly Splenomegaly Ascites Prominent abdominal collateral veins Bruits and rubs Abdominal masses Palpable gallbladder SIGNS OF “DECOMPENSATED” HEPATOCELLULAR DISEASE Jaundice Ascites

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Oliguric hepatic failure Hepatic encephalopathy Fetor hepaticus Asterixis Behavioral alterations (confusion, disorientation, failure to complete simple mental tasks)

a

This triad suggests chronic alcoholism.

The presence of lymphadenopathy, if generalized, suggests a lymphoproliferative disorder such as Hodgkin's disease or non-Hodgkin's lymphoma. Supraclavicular lymphadenopathy should raise the question of underlying malignant disease of the stomach or bronchopulmonary tract. Patients with pneumonia have jaundice in approximately 5% of cases; this is more likely to be the case among patients with pneumococcal pneumonia. Accordingly, a careful examination of the lungs is in order in the evaluation of patients with jaundice. Patients with congestive heart failure quite frequently have chronic passive congestion of the liver, which can result not only in jaundice but also in signs of portal-systemic encephalopathy. There are several peripheral stigmata of chronic parenchymal liver disease. Spider angiomata are usually found in the distribution of the superior vena cava and most commonly on the upper anterior chest, neck, face, and upper thorax. The presence of more than a dozen spider angiomata should raise the question of portal hypertension. The triad of gynecomastia, Dupuytren's contracture, and parotid enlargement should always raise the question of chronic alcoholism. Paucity of axillary and pubic hair and eye signs mimicking those of hyperthyroidism are often found among patients with advanced liver disease. Testicular atrophy, defined by a testicular diameter of less than 3 cm, is also common.

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▪ Figure 1.1 Determination of liver size by means of percussion over the lower right anterior chest and the right upper quadrant of the abdomen.

The abdominal examination is important in determining the liver size as well as the presence of an enlarged spleen. Percussion of the abdomen is important for several reasons. First, the size of solid organs such as the liver and spleen can be evaluated with percussion. One can often determine whether an increased amount of intraperitoneal fluid (ascites) is present. The upper and lower borders of liver dullness can be assessed by means of percussion along the right midclavicular line from the midchest to the midabdomen (Fig. 1.1). Liver size can be further assessed by having the patient inspire and observing the descent of the liver (Fig. 1.2). The lower border of liver dullness alerts the examiner to the site where the liver edge should be palpable. The liver span as judged by liver dullness measures 10 to 12 cm in men and 8 to 11 cm in women. A sudden decrease in liver dullness can occur in several conditions, such as viral hepatitis with the development of submassive or massive liver cell necrosis, localized dilatation of the transverse colon (as in toxic megacolon), fulminant colitis, and ileus associated with peritonitis or a perforated viscus (e.g., duodenal ulcer or diverticulitis). The spleen is normally P.8 not palpable. Percussion over the spleen reveals an area of dullness extending from the 10th rib in the posterior midaxillary aspect to the anterior aspect of the chest (Figs. 1.2 and 1.3). When the patient inspires, the area of splenic dullness moves inferiorly and to the right.

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▪ Figure 1.2 Photograph of abdomen and chest depicts the location of the liver and the spleen as outlined by means of percussion. The liver descends 1 to 3 cm with inspiration, which is reflected by a change in liver dullness.

The detection of splenic dullness is important for the following three reasons: 1. It may indicate splenic enlargement before the spleen can be palpated. 2. It alerts the examiner to the site where the spleen may be palpated. 3. Increasing dullness of the left flank may be a valuable clue to the diagnosis of traumatic rupture of the spleen or subcapsular hematoma.

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All quadrants of the abdomen must be palpated in an orderly manner. When palpating the abdomen, the hand should be warm and the palm and extended fingers of the right hand placed flat in a plane parallel to the surface of the abdomen (Fig. 1.4). The pads of the fingers are used together to perform light general palpation. Light palpation is used on the abdomen first, and as tense muscles relax, deeper palpation should be tried. Quick jabbing movements should be avoided. Any area of tenderness or any increased muscular resistance should be recognized and examined in detail. Percussion should alert the examiner to the approximate size and lower edge of the liver. Beginning at the right iliac fossa, the right hand is moved gradually upward until the edge of the liver is appreciated (Fig. 1.4). The patient can be asked to take a deep breath slowly. The descent of the diaphragm carries the liver down, which facilitates palpation of the liver edge. The edge of the liver can be felt in most healthy individuals if the patient's abdominal wall muscles are relaxed and the patient takes a slow, deep breath. In some healthy individuals, a very low lying thin segment of the liver can be palpated in the right lower quadrant. This is termed the Riedel lobe of the liver. An alternative approach to feeling the edge is to gently curl the fingers of the right hand below the costal margin and ask the patient to inspire slowly (Fig. 1.5). This is termed the Middleton method. In this manner, the liver descent is appreciated by the fingertips. This method is important in determining minimal enlargement of the liver or a liver palpable only in the epigastrium, as can occur in advanced cirrhosis. The examiner should determine whether the liver is soft, firm, hard, or irregular; whether the edge is rounded or sharp; whether discrete masses are present; and whether the left lobe is palpable across the midline. The presence of a palpable left lobe always denotes an abnormality, usually chronic liver disease. The size of the liver should be assessed as judged by the location of the edge below the right midclavicular line and the xiphoid. A normal liver edge is sharp, smooth, and not hard, and the left lobe is not palpable. A rounded edge suggests liver disease; a palpable left lobe suggests either chronic infiltrative or neoplastic liver disease. Modest enlargement of the liver occurs in several disorders, most notably viral hepatitis, chronic liver disease (all causes), chronic hepatitis, cirrhosis, choledocholithiasis, and extrahepatic biliary tract obstruction. Marked enlargement of the liver (edge >10 cm below the costal margin) occurs in relatively few disorders, which include (a) primary and metastatic tumors of the liver, including lymphoma, (b) alcoholic liver disease (fatty liver, alcoholic hepatitis, cirrhosis), (c) severe congestive heart failure, (d) infiltrative diseases of the liver, such as amyloidosis and myelofibrosis, and (e) chronic myelogenous leukemia. Finally, a pulsatile liver should raise the question of tricuspid regurgitation, which can occur with advanced mitral stenosis, endocarditis of the tricuspid valve, and severe

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pulmonary hypertension. Percussion of the left upper quadrant may have alerted the examiner to the presence of an enlarged spleen. Palpation of the spleen should begin in the left iliac fossa and move up to the left costal margin (Fig. 1.6). If the spleen is not felt while the patient is supine, the patient should roll onto his or her right side so the examiner can again examine the left upper quadrant (Fig. 1.7). P.9 This method takes advantage of the fact that when the spleen enlarges, it becomes more easily palpable inferiorly and medially. This enlargement is better appreciated when the patient is in the right lateral decubitus position. An alternative is for the examiner to stand at the patient's right side with the patient's left hand placed under the 11th rib to elevate the thorax. The examiner then curls the fingers of either one or both hands below the costal margin and asks the patient to inspire. The splenic margin may then be felt by the fingertips.

▪ Figure 1.3 Technique for percussion of the spleen. If splenomegaly is present, the percussion note is dull, and with inspiration, the spleen moves downward and medially and the percussion note changes accordingly.

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▪ Figure 1.4 Technique for palpation of the liver.

A common problem in evaluating left upper quadrant masses is differentiating the spleen and the left kidney. Palpation of a notch on the medial surface P.10 suggests that the organ being palpated is the spleen. Differentiation of the left lobe of the liver from the spleen can be difficult if massive hepatomegaly is present. One can usually discern a space or open area between the two organs. Common causes of splenomegaly include the following:

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▪ Figure 1.5 Alternative technique for palpation of the liver. The best results are obtained with gentle pressure of the curled fingers on the anterior abdominal wall.

▪ Figure 1.6 Technique for palpation of the spleen.

1. Portal hypertension caused by cirrhosis of the liver 2. Infections (viral, bacterial, fungal) 3. Leukemia, lymphoma, and Hodgkin's disease 4. Connective tissue diseases (systemic lupus erythematosus and rheumatoid arthritis) 5. Infiltrative disorders (amyloidosis and sarcoidosis)

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▪ Figure 1.7 Palpation with the patient in the right lateral decubitus position should be performed on all patients with suspected splenomegaly if the spleen is not felt with the patient in the supine position.

P.11 6. Hemolytic disorders 7. Myelofibrosis

Gallbladder The gallbladder, when enlarged, can often be palpated in the right upper quadrant at the angle formed by the lateral border of the rectus abdominis muscle and the right costal margin. The gallbladder is palpable in approximately 25% of cases of carcinoma of the head of the pancreas (Courvoisier's law) because of painless distention of the gallbladder. The gallbladder is also palpable in approximately 30% of patients with acute cholecystitis, often because stones are impacted in the neck of the gallbladder. Often in acute cholecystitis, rather marked right upper quadrant tenderness is present, and palpation can be difficult because of intense involuntary spasms of the abdominal muscles. Percussion over the right lower anterior chest and right upper quadrant often elicits pain. Another sign pointing to acute cholecystitis is right upper quadrant abdominal pain aggravated by inspiration (Murphy's sign). The patient is asked to inspire after the examining fingers are placed high in the

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right upper quadrant; inspiration causes the gallbladder to descend and come in contact with the extended fingers, causing pain and inspiratory arrest.

Bruits Bruits are systolic sounds usually produced by the turbulence of blood flowing through diseased or compressed blood vessels. The many causes of abdominal bruits are listed in Table 1.4. The most common causes of such bruits include calcification of the aorta, celiac axis compression, and alcoholic hepatitis. An epigastric bruit can be appreciated in 20% of healthy thin young adults, especially if auscultation is performed after a meal. Such bruits are usually caused by the compression of the celiac axis artery by muscle fibers of the crus of the diaphragm. Abdominal bruits are often important clues leading to the diagnosis of hepatocellular carcinoma, renal artery stenosis, fibromuscular hyperplasia of the renal arteries, intestinal angina, aortic aneurysm, and pancreatic cancer.

Peritoneal Friction Rub A friction rub heard over the liver suggests the diagnosis of liver metastasis or primary hepatocellular carcinoma. Other causes of hepatic friction rub include infarction of the liver (as in sickle cell anemia and polyarteritis nodosa) and liver abscess. A transient friction rub caused by a hematoma around the puncture site is common after liver biopsy but is usually not audible 4 to 6 hours after biopsy.

Table 1.4. Causes of Abdominal Bruit

Location of bruit Liver

Diagnostic considerations

Comment

Alcoholic hepatitis

Bruits may change day to day

Hepatocellular carcinoma

Suspect hepatocellular carcinoma in decompensated cirrhosis with a disproportionately increased serum level of alkaline phosphatase

Effect of surgery

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Portosystemic shunt

Hepatic artery aneurysm

Hepatic arteriovenous fistula (trauma)

Spleen

Splenic artery

May see calcification in

aneurysm

left upper quadrant on plain radiographs of the abdomen

Splenorenal shunt

Splenic arteriovenous fistula

Calcified aorta

Aorta

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Aortic aneurysm

Celiac axis

Bruits common in thin

compression

individuals, especially after meals

Celiac or superior mesenteric artery

Intestinal angina characterized by the triad

disease (atheroma,

of (a) bruit, (b) weight loss, and (c) postprandial

thrombi)

abdominal pain

Left

Pancreatic cancer

Bruit caused by

upper quadrant

(body or tail)

encasement of splenic artery or vein by tumor;

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present in 25% of cases

Umbilicus

Cruveilhier-

Bruit caused by increased

Baumgarten syndrome

flow through umbilical veins secondary to portal hypertensions

Renal artery stenosis (atheroma, emboli)

Renal artery

Bruit may be unilateral or

fibromuscular hyperplasia

bilateral

Renal artery aneurysm

P.12

Ascites Assessment of shifting dullness is often used to determine whether ascites is present. When free fluid is present in the abdomen, such fluid gravitates to the flanks, and the intestines float upward when the patient lies on his or her back. Percussion with the patient in this position discloses tympany over the anterior abdomen and dullness over the flanks. If the patient is turned to one side, the dullness shifts, and the percussion on the side that is uppermost becomes tympanic, because that area becomes occupied by gas-filled intestine. Another physical finding pointing to the diagnosis of ascites is the fluid wave. A fluid wave is demonstrated by tapping the left flank sharply with the right hand while the left hand is placed against the opposite flank (Fig. 1.8). Either the patient or a second examiner must place the ulnar surface of his or her hand along the midline of the abdomen. A positive test result is one in which an impulse on the opposite flank is percussed after the right flank is tapped. Neither the test for shifting dullness nor the test for a fluid wave uniformly reveals modest amounts of ascitic fluid (85%

syndrome

due to indirect

Aminotransferases Normal

phosphatase Normal

Prothrombin Albumin Normal

Globulin Normal

time Normal

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fraction

No bilirubinuria

Acute

Both fractions

Elevated, often

Normal to

hepatocellular

may be elevated;

>500 IU; ALT ≥

three times

Normal

Normal

Usually normal; >5

necrosis (viral

peak usually

AST

normal

s above

and drug

follows

control and

hepatitis,

aminotransferases

not

hepatotoxins,

corrected

acute heart

with

failure)

parenteral vitamin K suggests massive necrosis and poor prognosis

Bilirubinuria

Chronic

Both fractions

Elevated, but

Normal to

Often

Increased γ-

Often

hepatocellular

may be elevated

usually 2 suggests alcoholic hepatitis or cirrhosis

Cirrhosis

Intrahepatic

Both fractions

Normal to

Elevated,

Normal,

γ-Globulin

Normal; if

cholestasis

may be elevated

moderate

often over

unless

normal

prolonged,

elevations; rarely

four times

chronic

>500 U

normal

is corrected with parenteral vitamin K

Obstructive

Bilirubinuria

β-Globulin

jaundice

may be increased

Infiltrative

Normal to slightly

Elevated,

elevated

often over

normal; γ-

(tumor,

four times

globulin may

granuloma)

normal

be increased

diseases

Usually normal

Normal

Usually

Normal

in granulomatous disease

Partial bile

Fractionate, or

duct

confirm liver

obstruction

origin with 5′nucleotidase, γ-glutamyl transpeptidase

ALT, alanine aminotransferase; AST, aspartate aminotransferase. Kaplan M. Evaluation of hepatobiliary diseases. In: Stein JH, ed. Internal medicine. Boston: Little, Brown, 1990:443, with permission.

LFTs are less precise in the diagnosis of chronic hepatocellular disorders, such as cirrhosis. The activity of the disease and the degree of hepatic reserve vary, and the results of LFTs vary with the activity of the disease process and the amount of hepatic reserve. LFTs may be highly insensitive in cirrhosis. Patients with end-stage postnecrotic or alcoholic cirrhosis may have shrunken livers and striking portal hypertension, and yet have LFT results that are almost normal. Breath tests, serum bile acid tests, and measurements of the undercarboxylated form of prothrombin would all be useful in such patients. On the other hand, LFT results may be strikingly abnormal in patients with chronic hepatic disorders. A serum albumin level of less than 3 g/dL, increased Ig levels, a prothrombin time 3 or more seconds above control that is not set right with parenteral vitamin K, and aminotransferase levels that are elevated but less than 300 IU make the diagnosis of cirrhosis likely. An AST/ALT ratio greater than 2 raises the possibility of alcoholic liver disease, and an AST/ALT ratio greater than 3 is highly suggestive of this possibility. Alkaline phosphatase level is seldom helpful in the diagnosis of cirrhosis.

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Threefold or greater elevations should suggest the possibility of primary biliary cirrhosis in the setting of cirrhosis or portal hypertension. There is a characteristic pattern of LFTs in cholestasis, although the routine laboratory tests listed in Table 2.6 do not differentiate intrahepatic and extrahepatic cholestasis. Alkaline phosphatase level is usually elevated out of proportion to the levels of other enzymes. Values four or more times greater than normal suggest some type of cholestasis. Depending on the severity of the underlying condition, the bilirubin level is either normal or elevated. If elevated, the direct fraction is increased and bilirubin is present. Aminotransferase levels are usually elevated, but values greater than 500 IU (8.3 µkat/L) are rare. Aminotransferase levels are usually less than 300 IU (5 µkat/L), unless the tests are performed within 24 hours of the development of acute bile duct obstruction due, for example, to the passage of a common duct stone. Albumin and globulin levels are usually normal. Increased Ig levels suggest cirrhosis in patients with cholestasis. An increased IgM fraction suggests primary biliary cirrhosis. The antimitochondrial antibody test is helpful in this situation. The result is positive in 90% to 95% of patients with primary biliary cirrhosis, and negative in patients with extrahepatic bile duct obstruction or sclerosing cholangitis. The prothrombin time is usually normal. If elevated, it is commonly due to vitamin K deficiency and should correct with parenteral administration of vitamin K. Infiltrative liver diseases produce LFT abnormalities similar to those of partial bile duct obstruction. Often, the earliest and only abnormal value is alkaline phosphatase. If this is the case, or if the serum alkaline phosphatase level is elevated out of proportion to that of the other enzymes, it is helpful to identify the origin of the alkaline phosphatase. This can be done with electrophoretic techniques, or by means of measuring 5′-nucleotidase or GGT. The bilirubin level is often normal early in infiltrative disease, and is usually normal in partial bile duct obstruction. If the total serum bilirubin level is elevated, the direct fraction is certain to be elevated, and bilirubinuria is present. Aminotransferase levels are normal or minimally elevated in patients with infiltrative disease and partial bile duct obstruction, as are serum albumin and Ig levels and prothrombin time. The results of these laboratory tests suggest but seldom confirm a specific diagnosis. Once this information is obtained, the results facilitate the efficient use of other diagnostic tests, such as the serologic testing for hepatitis, echography, computed tomography, percutaneous liver biopsy, and cholangiography. With increasing experience, the breath and serum bile acid tests may be added to the list of routinely used tests in Table 2.6 or replace some of them. For example, serum bile acid tests may someday replace the direct bilirubin test as a general screening test for hepatic dysfunction. This has not yet occurred. Work continues on finding a test, or a combination of tests, that can eliminate the need for liver biopsy. Any conveniently performed inexpensive test that increases the diagnostic power of the standard LFT battery will be welcomed.

Footnote 1

SI units (Le Système International d’Unites) are gradually replacing other units to have one common, worldwide system for reporting

scientific data. The SI unit for enzymatic reactions is the katal, abbreviated kat. It replaces the international unit (IU/L) and denotes moles of substrate converted per second. For example, to convert alkaline phosphatase IU/L to SI units (µkat/L), multiply IU/L by 0.01667. The SI reference range for alkaline phosphatase is 0.5 to 2 µkat/L. This value may vary somewhat among laboratories.

Annotated References Brensilver HL, Kaplan MM. Significance of elevated liver alkaline phosphatase in serum. Gastroenterology 1975;68:1556. This paper describes the use of polyacrylamide gel electrophoresis to fractionate serum alkaline phos phatase in hundreds of patients with elevated serum alkaline phosphatase levels. The authors found that the elevation was caused by increased amounts of liver alkaline phosphatase in most patients and that patients with a variety of general medical disorders, such as congestive heart failure, Hodgkin's disease, and bacterial infection, could have a significant elevation in the level of serum alkaline phosphatase of hepatic origin. Clermont RJ, Chalmers TC. The transaminase tests in liver disease. Medicine 1967;46:97. The authors gathered all papers describing the evaluation of the AST (SGOT) test in the diagnosis of liver disease and determined the relation between the absolute value of the AST and the likelihood of a patient having obstructive liver disease, or, conversely, hepatocellular disease. The higher the AST level, the less likely for the patient to have obstructive P.57 jaundice. Fewer than 1% of patients with obstructive jaundice have AST values greater than 700 IU. Cohen JA, Kaplan MM. The SGOT/SGPT ratio: an indicator of alcoholic liver disease. Dig Dis Sci 1979;24:835. The authors found that the SGOT/SGPT (AST/ALT) ratio is helpful in the diagnosis of alcoholic liver disease. If the ratio is greater than 2:1, alcoholic liver disease is likely. Ninety-five percent of patients with ratios greater than 3:1 have alcoholic liver disease. Kaplan MM, Rhigetti A. Induction of rat liver alkaline phosphatase: the mechanism of the serum elevation in bile duct observation. J Clin Invest 1970;49:508. This paper showed that the mechanism of the elevated serum alkaline phosphatase level in cholestasis is the induction of liver alkaline phosphatase and the leakage of liver alkaline phosphatase in serum. The authors clearly showed that the alternative theory popular at the time—that the liver clears alkaline phosphatase made in other organs from serum and excretes it into bile much as the liver excretes bilirubin—was incorrect. This paper resolved a controversy that had existed in medicine for more than 50 years. Weiss JS, Gautam A, Lauff JJ, et al. The clinical importance of a protein bound fraction of serum bilirubin in patients with hyperbilirubinemia. N Engl J Med 1983;309:147. The authors demonstrate that conjugated bilirubin in serum binds covalently to a macromolecule in serum (most likely albumin), and that the bilirubin fraction is cleared slowly from serum with a half-life similar to that of albumin. This finding demonstrated why it often takes so long for an elevated serum bilirubin level to decline in certain situations, such as when mechanical bile duct obstruction is surgically corrected.

References 1. Lester R, Schmid R. Bilirubin metabolism. N Engl J Med 1964;270:779.

2. Robinson S, Lester R, Crigler JF Jr, et al. Early-labeled peak of bile pigment in man: studies with glycine-14C and delta aminolevulinic acid-3H. N Engl J Med 1967;277:1323.

3. Landow SA, Callahan EW Jr, Schmid R. Catabolism of heme in vivo: comparison of the simultaneous production of bilirubin and

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carbon monoxide. J Clin Invest 1970;49:914.

4. Tenhunen R, Ross ME, Marver HS, et al. Reduced nicotinamide-adenine dinucleotide phosphate-dependent biliverdin reductase: partial purification and characterization. Biochemistry 1970;9:288.

5. Scharschmidt BF, Waggoner JG, Berk PD. Hepatic organic anion uptake in the rat. J Clin Invest 1975;56:1280.

6. Zieve L, Hill E, Hanson M, et al. Normal and abnormal variations and clinical significance of the one-minute and total serum bilirubin determinations. J Lab Clin Med 1951;38:446.

7. Margulis SJ, Honig CL, Soave R, et al. Biliary tract obstruction in the acquired immunodeficiency syndrome. Ann Intern Med 1986;105:207.

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Editors: Title:

Schiff, Eugene R.; Sorrell, Michael F.; Maddrey, Willis C.


Copyright ©2007 Lippincott Williams & Wilkins > Table of Contents > Volume I > Section I - Overview: Clinical Fundamentals of Hepatology > Chapter 3 - Liver Biopsy and Laparoscopy

Chapter 3 Liver Biopsy and Laparoscopy Mical S. Campbell Lennox J. Jeffers K. Rajender Reddy

Key Concepts z

Liver biopsy is the traditional gold standard for the evaluation of chronic liver diseases. However, sampling error, particularly evident with small specimens, makes biopsy a flawed benchmark.

z

z

Percutaneous liver biopsy is a safe procedure both with or without radiologic guidance. Transjugular liver biopsies may be performed in patients with coagulopathies or other contraindications to percutaneous biopsy. Samples are often smaller and more fragmented.

z

Diagnostic laparoscopy with liver biopsy is a low-risk, outpatient procedure performed under conscious sedation. Direct visualization of the liver surface improves the identification of cirrhosis and facilitates the staging of metastatic and primary cancers.

z

Noninvasive panels of serologic markers are being studied to accurately grade and stage chronic liver disease, particularly hepatitis C. Transient elastography is a promising new technology for assessing hepatic fibrosis.

z

The role of liver biopsy has been challenged in a number of clinical scenarios, including management of viral hepatitis, nonalcoholic fatty liver disease, monitoring of methotrexate hepatotoxicity, and in the diagnosis of hepatocellular carcinoma. In select cases, clinical, laboratory, and radiologic imaging data may obviate the need for a biopsy.

Introduction Liver biopsy was first performed in 1883 by Paul Ehrlich (1). The procedure was lengthy and impractical until Menghini reported a quick “one-second” aspiration technique in the late 1950s (2). Transjugular hepatic vein catheterization in 1967 introduced a new biopsy technique with less risk for bleeding (3). Other technologic advances have expanded technical options for the performance of a liver biopsy. At present, large numbers of liver biopsies are performed safely each year, although life-threatening complications ensue occasionally. A variety of needles can be used during a percutaneous, transjugular, or laparoscopic approach. Both hepatologists and radiologists commonly perform biopsies either “blindly” or under radiologic guidance. Choice of technique depends on the

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available expertise and the clinical situation. Percutaneous biopsy, with or without radiologic guidance, is most commonly performed and has a long track record of safety. The transjugular approach is often used when there are contraindications to percutaneous biopsy, such as a bleeding diathesis, obesity, or ascites. Laparoscopic liver biopsy is a more invasive procedure that is useful for the evaluation of various intra-abdominal malignancies and ascites of unknown cause. Fine-needle aspiration of focal liver lesions can be performed under radiologic guidance. Liver biopsy has traditionally been the gold standard for the evaluation of chronic liver diseases. Recently, noninvasive markers of fibrosis and inflammation have been introduced, particularly for the evaluation of hepatitis C. As experience with these new techniques P.62 grows, biopsy may be avoided in some clinical situations. Furthermore, with the advent of specific serologic testing, the need for liver biopsy has been challenged in some clinical scenarios. In hepatitis B and C, biopsy is useful, but not mandatory in making the decision to initiate treatment. Nonalcoholic fatty liver disease (NAFLD) can be diagnosed on the basis of clinical and imaging features, and biopsy generally does not influence management decisions. The role of periodic liver biopsy to assess for hepatotoxicity in patients taking methotrexate remains controversial. Finally, the role of liver biopsy in hepatocellular carcinoma (HCC) has become contentious because characteristic features on radiologic imaging, complemented by an elevated α-fetoprotein can now accurately diagnose these lesions.

Percutaneous Liver Biopsy Before a percutaneous liver biopsy is performed, the patient must be prepared properly. A complete physical examination and history, review of medications, and measurement of clotting parameters are essential. Criteria for the safe performance of an outpatient biopsy and contraindications to a percutaneous approach are listed in Tables 3.1 and 3.2 (4). Explaining the procedure and possible minor and major complications and obtaining written consent from the patient are mandatory (5). It is preferred that prothrombin time, partial thromboplastin time, and platelet count be measured within 4 weeks of biopsy. Salicylates and nonsteroidal anti-inflammatory drugs are discontinued for 1 week before and 1 week after biopsy. A light breakfast 2 to 3 hours before the procedure can facilitate gallbladder emptying and may reduce the risk of gallbladder puncture. Alternatively, an overnight fast can be advised, particularly when conscious sedation is used, to reduce the risk of aspiration in case of vomiting. Venous access is established, preferably in the left arm, so that the patient can lie comfortably in the right lateral decubitus position after the biopsy. Patients are frequently anxious, and intravenous fentanyl and midazolam can alleviate apprehension, facilitate the procedure, provide some postprocedure relief of pain, and achieve some degree of amnesia. Most patients do well with approximately 50 µg of fentanyl and 2 mg of midazolam without impairment of their ability to cooperate with the biopsy. Older patients may require less sedation.

Table 3.1. Criteria for Outpatient Liver Biopsy

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Patient must be able to return to the hospital in which the procedure was performed within 30 min of adverse symptoms Patient must have a reliable individual staying with him or her during the first night after biopsy to provide care and transportation, if necessary Patient should have no complications or associated serious medical problems that increase the risk of the biopsy Facility in which the biopsy is performed should have an approved laboratory and blood banking unit, easy access to an inpatient bed, and personnel to monitor patient for at least 6 h after the biopsy Patient should be hospitalized after the biopsy if any serious or persistent complications develop

Table 3.2. Contraindications to Percutaneous Liver Biopsy

ABSOLUTE Uncooperative patient Bleeding tendency Prothrombin time ≥4 s over control, international normalized ratio ≥1.5 Platelet count 1.5) Thrombocytopenia (platelets 1.5). A study has observed that patients with mild thrombocytopenia (50,000 to 99,000/µL) or prothrombin times prolonged by less than 4.2 seconds do not have increased risk of bleeding after percutaneous liver biopsy (65). Such patients may not benefit from prebiopsy platelet transfusion or fresh frozen plasma administration. The use of prophylactic fresh frozen plasma for a prothrombin time of 4.0 seconds or more (INR ≥1.5) with rechecking of the prothrombin time after infusion has been recommended and widely adopted. However, data supporting this practice are not available (66). In a recent retrospective study among patients with severe thrombocytopenia and hematologic malignancy, transjugular liver biopsy was safely performed after platelet transfusion to a median posttransfusion platelet count of 30,000/µL. The authors propose 30,000/µL as a threshold for platelet transfusion before performing the transjugular liver biopsy (67). Until better safety data are available, we recommend the transjugular approach with prophylactic platelet transfusion for patients with platelet count less than 60,000 µL. For patients with either thrombocytopenia or increased prothrombin time, the use of fibrin glue may prevent bleeding. In this patient population, percutaneous biopsy followed by injection of fibrin glue to seal the tract has been performed with good safety

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(68,69). We do not recommend the routine use of bleeding time to assess the risk of bleeding after liver biopsy. Bleeding time measurement is controversial and is unlikely to provide much value (70,71). Patients with chronic renal failure may have deficient platelet functioning despite a normal platelet count. Dialysis performed the day before the procedure or the use of deamino-8-D-arginine vasopressin (DDAVP) just before the procedure has been advocated, but should not be regarded as mandatory. A recent study of patients with chronic renal failure did show a significantly lower rate of major hemorrhage after transjugular liver biopsy, as compared to percutaneous puncture (72). Patients taking an oral anticoagulant should discontinue the drug at least 72 hours before liver biopsy, provided discontinuation is not contraindicated. Heparin may be started approximately 24 hours after the biopsy. Immediate restarting of oral anticoagulation after biopsy is not preferred because delayed bleeding has been reported in patients taking oral anticoagulants (73,74). It is preferred that oral anticoagulation be restarted 48 to 72 hours after biopsy. Aledort et al. (75) reported a rate of significant bleeding as high as 12.5% among hemophiliacs who underwent liver biopsy before 1981 (75). This high bleeding rate prompted serious concerns regarding biopsy in this population, but other studies have not reproduced those results. Reports of percutaneous liver biopsies performed in hemophiliacs during short hospitalizations with clotting factor replacement have shown no significant bleeding (76,77,78,79,80,81). Case series of transjugular liver biopsies performed in hemophiliacs after clotting factor infusions have also demonstrated excellent safety (82,83,84,85).

Laparoscopy Use of laparoscopy to evaluate liver disease is well established in Continental Europe, but is much less frequently performed in North America than in other parts of the world. During laparoscopy, direct inspection of the liver surface is performed and tissue is acquired. The procedure can be performed under conscious P.67 sedation in the outpatient setting. Recent introduction of mini-laparoscopy and laparoscopic ultrasonography has made the procedure potentially safer and more attractive.

Technique Although laparoscopy is commonly performed under general anesthesia, the safety and efficacy of outpatient diagnostic laparoscopy using conscious sedation has been demonstrated (86,87,88). In some centers, diagnostic laparoscopy is performed in the endoscopy suite. With the patient in a supine position, the abdomen is scrubbed with povidone-iodine (Betadine) and covered with sterile drapes. Application of 2-L oxygen by nasal cannula and monitoring with electrocardiography and pulse oximetry are recommended (89,90). The Veress needle and trocar are usually placed in the left paramedian area; however, a right paramedian or subumbilical approach can be used in patients with an enlarged left hepatic lobe, splenomegaly, or previous splenectomy (Fig. 3.3). A local anesthetic (1% lidocaine) is injected intradermally 2 cm above and to the left of the umbilicus (Fig. 3.4A). Then, a 16-gauge needle is inserted through the center of the wheal to the parietal peritoneum, which usually provokes some

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pain. Approximately 15 to 20 mL of 1% lidocaine is applied to the subcutaneous tissue and fascia within a 2-cm radius. It is important that sufficient local anesthesia be applied. A small incision is made in the center of the wheal, and the patient is asked to distend the abdominal wall without arching the back. The Veress needle is then inserted into the abdominal cavity, and two distinct “pops” are heard (91). Aspiration with a 10-mL syringe may avoid air embolism or inadvertent entry into the intestines, both of which are rare complications (92,93). Whereas carbon dioxide used for insufflation during therapeutic laparoscopy is a peritoneal irritant and provokes pain, the nitrous oxide commonly used for diagnostic laparoscopy is better tolerated (89,90). Insufflation to an abdominal cavity pressure of 20 mm Hg is accomplished by delivering 3 to 6 L of nitrous oxide through the Veress needle (Fig. 3.4B). A 20-mL syringe, half filled with saline solution, is then inserted and rotated within the abdominal cavity. Gas bubbles within the syringe indicate an unobstructed area for trocar placement. The patient is then instructed to distend the abdomen, and the trocar is inserted into the peritoneal cavity. Two distinct “pops” confirm placement. An oblique-view laparoscope is then inserted into the abdominal cavity under direct vision. The area perpendicular to the scope is inspected for insertion-related damage. With the patient in Trendelenburg's position, the bladder and other pelvic structures can be visualized. Placement of the patient in reverse Trendelenburg's position allows thorough inspection of the right and left upper quadrants (94). A second trocar is inserted into the right midclavicular line to allow, via another laparoscope, the inspection of the superior aspect of the right lobe and the delivery of accessory equipment, such as the biopsy needle and palpating probe. Liver specimens are obtained with a biopsy gun or, less commonly, a Tru-Cut needle. To avoid large blood vessels, a tangential approach to the liver left of the falciform ligament is recommended (Fig. 3.4C,D,&E). More recently, mini-laparoscopy has been described with use of a 1.9-mm end-viewing instrument (95,96,97). A randomized study between mini- and conventional laparoscopy demonstrated similar success with both procedures, and shorter procedure time with mini-laparoscopy (97).

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▪ Figure 3.3 Veress needle and trocar entry sites. A, Secondary trocar site for the visualization of the superior aspects of right lobe and placement of accessory equipment. B, Alternate site in patients with splenomegaly or previous left upper quadrant surgery. C, Preferable site with excellent view of left lobe. D, Subumbilical alternate site, least vascular.

After the examination is completed, the trocar and biopsy sites can be closed with Steri-Strips or by sutures if larger incision is made to accommodate larger trocars and laparoscopes (Fig. 3.4F). Patients are observed for approximately 18 to 24 hours postprocedure and discharged to resume regular activity in 3 to 4 days. Right shoulder pain for 6 to 8 hours after the procedure is common. In a survey of 215 patients with gastrointestinal malignancies who underwent outpatient P.68 P.69 staging laparoscopy under conscious sedation, only 7% required narcotics 2 to 5 hours after the procedure (87).

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▪ Figure 3.4 A: Laparoscopic site with injection of local anesthetic to the left of the umbilicus. B: Nitrous oxide placed through Veress needle with assistant verifying the loss of hepatic dullness. C: Laparoscopic guidance of biopsy gun. D: Palpation probe on biopsy site after procedure to ensure hemostasis. E: Three-millimeter mini-laparoscope visualizing the original laparoscopic trocar site for signs of bleeding. F: Completion of procedure; laparoscopic site closed with Steri-Strips.

Patients should avoid nonsteroidal anti-inflammatory drugs and salicylate

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compounds for 1 week before and after the procedure. Recommendations for patients with clotting factor and platelet count abnormalities are similar to those of percutaneous liver biopsy. In patients with end-stage renal disease, laparoscopy can be performed safely the day after dialysis with careful observation of the biopsy site before the procedure is terminated (98). Recently, the use of recombinant factor VIIa before laparoscopic liver biopsy has been reported (99). Moreover, mini-laparoscopy appeared safe in a small study of 61 patients with a platelet count less than 50,000/µL and/or INR greater than 1.5 (100). Most patients required the application of argon plasma coagulation directly to the liver to stop postbiopsy bleeding; there were no reports of delayed bleeding (100).

Indications for Laparoscopy Laparoscopy allows direct visualization of the liver and can be performed for a variety of indications (Table 3.7). Although reporting of laparoscopic findings has not been rigorously standardized, chronic liver disease causes a spectrum of changes in the gross appearance of the liver (Fig. 3.5). In patients with mild disease, the surface of the liver tends to appear smooth. With more advanced disease, granularity or early nodularity may be seen. Cirrhosis is associated with diffuse nodularity and features of portal hypertension. Liver biopsy specimens tend to understage the degree of fibrosis assessed by laparoscopic inspection. Liver biopsy, while specific for cirrhosis, may be up to 30% less sensitive for demonstrating cirrhosis as compared to laparoscopy (95,96,97,101,102). Furthermore, specific laparoscopic features, including the presence of irregular regenerative nodules, a high degree of nodular regeneration, and an atrophic right lobe, may predict the development of HCC in patients with hepatitis C cirrhosis (103).

Table 3.7. Indications for Diagnostic Laparoscopy

Chronic liver disease Hepatocellular carcinoma Benign hepatic tumors Staging of gastrointestinal malignancy Metastatic liver disease Ascites of unclear cause Peritoneal infection Lymphoma Fever of unknown origin Evaluation of abdominal mass Chronic abdominal pain Hepatosplenomegaly of unclear cause Liver disease in renal failure Assessment for liver transplantation Subfulminant hepatic failure

Diagnostic laparoscopy can help in evaluating ascites of unknown cause. During laparoscopy, tuberculous peritonitis commonly appears as miliary lesions in the parietal peritoneum and occasionally in the liver. Thick adhesions of the bowel to the parietal peritoneum may be seen (104). In one series, tuberculous peritonitis

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was associated with ascites in only 60% of cases (105). Chu et al. (106) performed 129 laparoscopies for ascites of unclear cause (106). They reported peritoneal carcinomatosis in 61%, tuberculous peritonitis in 20%, a nondiagnostic procedure or miscellaneous causes in 14%, and cirrhosis in 5% of cases. Laparoscopy may also identify lymphoma in patients with human immunodeficiency virus (HIV) and ascites (107). Laparoscopy is used both diagnostically and therapeutically in the management of HCC. The liver surface may demonstrate changes suggestive of HCC, such as hypervascular nodules and hyperemic, pigmented lesions (108). The risk of sampling HCC is controversial, but most cases of biopsy-proven seeding of the needle track have been reported after percutaneous biopsy (109, 110). Laparoscopy can also be used in patients with suspected HCC to assess the extent of the primary lesion and to examine other areas for synchronous tumors (111). In addition, it may be helpful to perform laparoscopy in patients with rising levels of α-fetoprotein and unrevealing imaging studies. Furthermore, laparoscopy with ultrasonography is superior in the diagnosis of HCC compared to laparoscopy alone (112). Local therapy with ethanol injection, microwave coagulation, or radiofrequency ablation has been applied laparoscopically or percutaneously; nevertheless, recurrence of HCC at the port site has been described after local therapy (113, 114). Laparoscopy is effective for staging a variety of cancers. In a study of pancreatic cancer, laparoscopy identified metastases undetected by CT scan in 31% of patients (115) (Fig. 3.6). Other studies have validated the usefulness of laparoscopy to help identify pancreatic cancer patients who could benefit the most from surgical resection (115,116,117,118,119). In a decision analysis model comparing multiple strategies for the staging and treatment of pancreatic cancer in which CT scan was performed first, endoscopic ultrasonography followed by laparoscopy was shown to minimize costs and unnecessary surgical explorations (120). Laparoscopic staging is also valuable in identifying surgical candidates for the management of cancers of the esophagus, stomach, ampulla, and bile ducts (121). Finally, laparoscopy is a valuable aid in staging lymphoproliferative diseases and requires the conversion to an open procedure in less than 5% of cases (122,123,124). In one P.70 study, laparoscopy was more sensitive than CT scan for the detection of lymphomatous invasion of the liver. White spots or nodules visualized during laparoscopy were 100% specific for lymphoma (125). As imaging technologies continue to evolve, the added value to performing staging laparoscopy must be assessed on an on-going basis.

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▪ Figure 3.5 Progression of hepatitis C in four different stages. A: Smooth appearance of liver, stage I histology. B: Finely granular appearance of liver, stage II. C: Uneven surface with early nodularity (early cirrhosis). D: Nodular liver with large regenerating nodule in the superior aspect of the right lobe.

Introduction of laparoscopic ultrasonography has further improved the accuracy of staging gastrointestinal malignancy (126). During laparoscopic ultrasonography, the liver parenchyma is swept with a linear array probe placed in contact with the liver surface. The operator can also obtain tissue samples and perform radiofrequency ablation. General anesthesia is commonly used. The value of laparoscopic ultrasonography has been demonstrated in a number of settings. In a prospective study, laparoscopic ultrasonography prevented unnecessary laparotomy in 65% of patients referred for the resection of HCC (127). Moreover, laparoscopic ultrasonography changed surgical decision making in 36% of patients referred for the staging of pancreatic carcinoma; 5% of those patients had appeared unresectable by conventional imaging (128). Laparoscopic ultrasound may also play a role in staging tumors of the proximal bile duct and gallbladder (129).

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▪ Figure 3.6 Staging laparoscopy in a patient with pancreatic carcinoma; 8mm lesion with crater seen in the left lobe.

Complications of Laparoscopy In a large series of 1,794 diagnostic laparoscopies, major complications occurred in only 8 patients (0.44%), minor complications were observed in 31 patients (1.73%), and one death occurred (93) (Table 3.8). Minor complications, such as vasovagal reactions, subcutaneous emphysema, pneumoperitoneum, and abdominal pain, can be controlled during the procedure (93,130,131,132,133). Bleeding from the biopsy site is controlled with the application of lateral pressure, use of a heater or bicap probe, or the topical application of thrombin. Delayed bleeding or hemobilia is seen primarily in patients with portal hypertension. Bowel perforation can be a risk in patients with a history of multiple surgeries, bacterial peritonitis, or tuberculous P.71 peritonitis (93,106). If the trocar site is found to be bleeding, a second trocar can be inserted to visualize the bleeding source. Avitene plugs placed within the trocar track are generally effective in stopping bleeding.

Table 3.8. Complications of Diagnostic Laparoscopy in 1,794 Patients at the University of Miami (93)

Complication

No. (%)

MAJOR

Abdominal viscus perforation

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3 (0.16)

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Bleeding from liver biopsy site

2 (0.11)

Hemobilia

2 (0.05)

Spleen laceration

1 (0.05)

Total

8 (0.37)

MINOR

Ascitic fluid leakage

9 (0.50)

Abdominal wall hematoma

6 (0.33)

Fever

6 (0.33)

Vasovagal reaction

5 (0.27)

Prolonged abdominal pain

4 (0.22)

Seizures

1 (0.05)

Total

31 (1.70)

Noninvasive Surrogates for Biopsy Although liver biopsy is generally considered the gold standard for the evaluation of liver disease, sampling errors may limit its accuracy. In contrast, noninvasive markers may potentially represent a more global assessment of liver injury. Furthermore, noninvasive methods may be safer, more attractive to patients, and cheaper than biopsy. Three main types of surrogates for biopsy have been investigated: Indirect markers (aspartate aminotransferase [AST] to alanine aminotransferase [ALT] ratio, aspartate aminotransferase to platelet ratio index [APRI], FibroTest, and ActiTest), direct markers of extracellular matrix turnover (hyaluronic acid and YKL-40), and ultrasonographic evaluation of liver stiffness (FibroScan) (Table 3.9). Most studies have focused on the evaluation of the extent of fibrosis and degree of inflammation in hepatitis C. Noninvasive identification of significant fibrosis (often defined as portal fibrosis with some septae) allows stratifying patients with hepatitis C most in need of therapy.

Table 3.9. Noninvasive Surrogates for Biopsy

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Test

Description

Comments

INDIRECT MARKERS

AST/ALT

Simple index derived from

Ratio >1 has limited

ratio

widely available blood tests

accuracy in predicting cirrhosis in viral hepatitis and NAFLD

APRI

Ratio of AST/upper limit

Good prediction of

normal to platelet count ×

significant fibrosis in

100

hepatitis C (APRI 1.5 predict absence and presence, respectively) Good prediction of cirrhosis in hepatitis C (APRI 2.0 predict absence and presence, respectively)

FibroTest

ActiTest

Commercially available panel of α 2 -macroglobulin,

Good prediction of

haptoglobin, apolipoprotein

significant fibrosis and cirrhosis in hepatitis C

A1, GGT, bilirubin

and B

Commercially available panel which consists of all

Reliable prediction of moderate activity in

elements of FibroTest and includes ALT

hepatitis C and B

DIRECT MARKERS

Hyaluronic

Marker for extracellular

Very sensitive for

acid

matrix turnover

cirrhosis in viral hepatitis and alcoholic liver disease. Low value rules out cirrhosis

YKL-40

OTHER

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Some utility to predict fibrosis

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FibroScan

Transient elastography

Excellent test for fibrosis

Probe induces vibration and ultrasonographically

and cirrhosis in hepatitis C. Has not been evaluated

measures transmission through liver to estimate

in populations with significant obesity

stiffness (fibrosis)

AST, aspartate aminotransferase; ALT, alanine aminotransferase; APRI, aspartate aminotransferase to platelet ratio index; NAFLD, nonalcoholic fatty liver disease; GGT, γ-glutamyl transferase.

Receiver operator characteristics (ROC) curve analysis is an important method to compare the test characteristics of noninvasive markers. ROC curves plot the sensitivity and specificity achieved for different test thresholds. Excellent diagnostic tests are those that achieve good sensitivities and specificities over a wide range of possible test “cutoff” values. Area under the receiver operator characteristics curve (AUROC) greater than 0.9 is excellent and that between 0.8 and 0.9 indicates a good test. Noninvasive markers cannot be expected to achieve perfect test characteristics because these panels are compared to liver biopsy, P.72 a modality that does not perfectly assess global liver injury. When only large biopsies are used as the gold standard, noninvasive markers have demonstrated better test characteristics (134,135). Simple, widely available, noninvasive tests have some value in predicting cirrhosis. Ultrasonography is widely used in the evaluation of liver diseases. It is moderately specific for identifying cirrhosis, but not sensitive (136). An increased AST/ALT ratio greater than 1 helps identify cirrhosis in viral hepatitis and NAFLD, particularly if the increased ratio is associated with a platelet count of less than 130,000/µL (137,138,139). Furthermore, APRI has demonstrated excellent ability to predict cirrhosis (AUROC 0.89 to 0.94) and good ability to predict significant fibrosis (AUROC 0.80 to 0.88) in patients with hepatitis C (140). A recent study in patients with hepatitis C confirmed good test characteristics for APRI, but observed that the AST/ALT ratio was a poor test (AUROC = 0.57 for significant fibrosis and AUROC = 0.73 to 0.75 for cirrhosis) (141). The MULTIVIRC group studied 339 patients using a panel of five nonroutine serum markers (α 2 -macroglobulin, haptoglobin, apolipoprotein A-I, γ-glutamyl transferase, and total bilirubin) in patients with hepatitis C. This panel of markers, now known as FibroTest, demonstrated an AUROC between 0.83 and 0.85 for the prediction of significant fibrosis. Fifty percent of patients could be accurately stratified using the test and could thereby avoid a liver biopsy (142). Subsequent studies have validated these findings in other people with hepatitis C (134,143,144,145). A somewhat less robust prediction has been demonstrated in chronic hepatitis B (146). Moderate or severe activity in hepatitis C can be predicted accurately by the ActiTest, which uses the same set of markers as FibroTest and also includes ALT (134). In hepatitis B, reliable prediction of moderate or severe activity was achieved with the ActiTest (AUROC = 0.82), which was similar to the prediction simply by AST or ALT tests (AUROC = 0.82,

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0.81, respectively) (146). Forns et al. (147) developed another panel of markers (age, platelet count, γ-glutyl peptidase, and cholesterol) with good ability to predict significant fibrosis in hepatitis C (147). Direct markers of extracellular matrix formation and removal have demonstrated less clinical utility to date. Hyaluronic acid is very sensitive (97%) for cirrhosis in viral hepatitis and alcoholic liver disease, and a low level can be used to rule out cirrhosis (148,149). Different test thresholds must be used for different etiologies of liver disease (148). YKL-40 is a glycoprotein involved in tissue remodeling and has also shown some utility as a predictor of fibrosis (149). Recently, a combination of hyaluronic acid, tissue inhibitor of metalloprotease-1, and α 2 macroglobulin was successfully used to identify significant fibrosis in hepatitis C (AUROC = 0.83) (150). Transient elastography (FibroScan) is a promising new technique to evaluate fibrosis. A probe applied to the abdomen transmits a low-frequency vibration. The vibration induces an elastic shear wave, which is propagated faster in stiffer (more fibrotic) liver tissue. Ultrasonographic interrogation of the wave allows measuring the shear wave velocity. Tissue elasticity can then be determined. FibroScan has demonstrated good prediction of significant fibrosis and excellent prediction of cirrhosis (135,151). A potential concern with the technique is that it has so far been studied only among French patients with relatively low body mass indices. How successful FibroScan will be in higher body mass index (BMI) populations, such as in the United States, is not yet known. A recent study compared noninvasive assessment of fibrosis in patients with hepatitis C using APRI, FibroTest, and FibroScan (145). All three tests achieved similar AUROC for the evaluation of significant fibrosis and cirrhosis. The authors suggest that the use of FibroTest and FibroScan together achieves the most accurate assessment of fibrosis. However, it is not obvious that the diagnostic combination is much better than performing one test alone. Cost-effectiveness studies are needed to help clarify the role of these new technologies.

Indications for Liver Biopsy Liver biopsy is often an important component of the evaluation of chronic liver disease. With advances made in serologic and imaging tests, its use in some situations has been challenged. We describe in the subsequent text some disease states in which the routine use of liver biopsy has been questioned (Table 3.10).

Hepatitis C Chronic hepatitis C infection globally affects approximately 170 million individuals. Candidates for treatment need to be carefully selected because hepatitis C therapy is associated with significant side effects, considerable expense, and less-than-ideal response rates, particularly in genotype 1 patients. Furthermore, most infections are asymptomatic and not progressive (152). Liver biopsy aids in identifying treatment candidates because it is currently the best predictor of progressive disease. On the basis of retrospective data, most patients with moderate inflammation develop cirrhosis within 20 years and nearly all patients with severe inflammation or bridging fibrosis develop cirrhosis within 10 years. Patients with mild inflammation and/or minimal fibrosis have a low risk of progression to cirrhosis (153). Hepatic steatosis is also emerging as a major risk factor for fibrosis progression in hepatitis C (154,155). P.73

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As experience with FibroTest, FibroScan, APRI, and other noninvasive markers grows, fewer biopsies will likely need to be performed to evaluate the urgency of initiating hepatitis C treatment.

Table 3.10. Utility of Biopsy in Specific Clinical Situations

Issue

Pros of biopsy

Cons of biopsy

HEPATITIS C

Prognosis

Extent of fibrosis and

Noninvasive markers may

inflammation are best predictors of disease

accurately stage and grade disease

progression

Decision to

Genotype 1: Identify

Genotypes 2 and 3: Patients

treat

those most in need of therapy (therapy

motivated for therapy may forgo biopsy (therapy shorter

longer in duration and less likely to

in duration and more likely to succeed)

succeed)

Treatment-

Severity of liver

Commitment to therapy

related side effects

disease helps in deciding whether to

should be independent of disease severity

endure or stop therapy

Previously treated

Lower success with retreatment Identify

Motivated patients who are genotype 2 or 3, were

those most in need of therapy (advanced

previously treated with interferon monotherapy, had

fibrosis)

significant dose reductions, or were on-treatment responders have relatively good prospects for response to retreatment

HEPATITIS B

Decision to

Consider biopsy if

Hepatitis B serologies,

treat

minimal elevation or fluctuating ALT;

hepatitis B virus DNA, and ALT generally determine

consider treatment if at least moderate

decision to treat

inflammation

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Identify

Prompts screening for

HCC surveillance

cirrhosis

varices and HCC

recommended whether cirrhosis is present or not

ABNORMAL HEPATIC BIOCHEMICAL TESTS AND NAFLD

Elevated

Confirm diagnosis

ALT

Cause accurately identified clinically in >90% cases without biopsy

Diagnosis of

Patients may not

Accurate diagnosis of NAFLD

NAFLD

have classic NAFLD

generally possible without

risk factors

biopsy

Identify

Only biopsy can

Noninvasive markers may be

severity of NAFLD

distinguish simple steatosis from

developed to distinguish the two

steatohepatitis

Treatment of NAFLD

Presence of steatohepatitis or

There is no proven therapy for NAFLD Absence of

fibrosis may motivate

steatohepatitis or fibrosis may

some to undertake

remove motivation for some

risk factor modification

to undertake risk factor modification

ALT, alanine aminotransferase; HCC, hepatocellular carcinoma; NAFLD, nonalcoholic fatty liver disease.

Liver biopsy may also reveal unsuspected cirrhosis, which would prompt initiation of a surveillance strategy for HCC and esophageal varices. Presence of advanced fibrosis is also negatively associated with the probability of response to hepatitis C therapy. In a study of pegylated interferon-α 2b with ribavirin, the absence of bridging fibrosis or cirrhosis was significantly associated with a sustained virologic response (57% vs. 44%) (156). Clinical information may help refine prognosis but cannot substitute for the valuable data obtained from biopsy. Risk factors for accelerated fibrosis progression include age at infection greater than 40 years, daily alcohol consumption, male gender, ALT, increased BMI, immunosuppression, and coinfection with hepatitis B or HIV (157,158,159,160,161,162,163,164). Twentyfive percent to 40% of patients with chronic hepatitis C have persistently normal ALT levels (165,166). This group tends to exhibit less fibrosis and inflammation than patients with hepatitis C and elevated ALTs (167). Moreover, in one study of 102 patients, the median progression of fibrosis was twice as fast in an elevated ALT group compared to a persistently normal ALT group (168). Despite these

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reassuring findings, patients with persistently normal ALTs may have significant inflammation (19% with moderate inflammation) (169) and even cirrhosis (6%) (170). Although the information obtained from liver biopsy is useful, it is not mandatory to perform biopsy before treating hepatitis C. Patients with genotype 2 or 3 may undergo therapy regardless of findings on liver biopsy because therapy is likely to succeed (80%) and its duration is short (24 weeks). Biopsy is more useful for genotype 1 patients. Because therapy is long in duration (48 weeks) and less likely to succeed (400 ng/mL) may help confirm the diagnosis (210). Biopsy of HCC carries a significant risk of needle-track seeding (1.6% to 5%)

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(109,205,206). A recent report of a polyethylene shield device may reduce that risk, but is as yet unproven (211). If a diagnosis of HCC can be confidently made on the basis of imaging with or without the help of α-protein, we do not perform fine-needle liver biopsy to confirm the diagnosis. At our institution, biopsy of HCC is generally reserved for patients in whom no definitive surgical intervention is planned and can be obtained at the time of nonsurgical treatment (radiofrequency ablation, alcohol ablation, or chemoembolization).

Conclusion Liver biopsy is a time-honored and safe method to evaluate chronic liver diseases. Growing evidence suggests that biopsies may not be representative of disease processes affecting the entire liver, especially when small samples are obtained. Biopsy is generally performed percutaneously with or without radiologic guidance. Transjugular biopsies may be performed on P.76 patients with ascites, obesity, or a bleeding diathesis. Laparoscopy, more commonly used in Continental Europe, is a safe outpatient procedure useful for accurately determining the presence of cirrhosis and for staging various gastrointestinal cancers. Recently, panels of markers that can serve as surrogates to biopsy in identifying the extent of fibrosis and inflammation have been introduced. As experience grows with these tests, it is possible that performance of biopsy may decline in some clinical situations, such as identifying candidates for hepatitis C therapy. Routine use of biopsy has been questioned in a number of clinical scenarios. In hepatitis C, biopsy may help stratify which patients are at risk for progressive disease and therefore most in need of therapy. Genotype 2 or 3 patients have a high response rate and a shortened treatment course and may therefore opt for therapy without biopsy. In hepatitis B, biopsy generally does not affect treatment decisions except in the subset of patients with minimally elevated or fluctuating transaminase levels. Distinction of NASH from bland steatosis can only be accomplished by biopsy. In the absence of any specific therapy for patients with either NASH or NAFLD, biopsy results currently do not affect management decisions. In monitoring methotrexate toxicity, the need for periodic liver biopsy has been questioned, and most patients can avoid biopsy if transaminases remain relatively normal. Finally, radiologic imaging can now accurately diagnose HCC without risking possible needle-track seeding from biopsy.

Annotated References Castera L, Vergniol J, Foucher J, et al. Prospective comparison of transient elastography, Fibrotest, APRI, and liver biopsy for the assessment of fibrosis in chronic hepatitis C. Gastroenterology 2005;128:343–350. This comparison of three non-invasive surrogates for liver biopsy showed good to excellent test characteristics for all three modalities. Guido M, Rugge M. Liver biopsy sampling in chronic viral hepatitis. Semin Liver Dis 2004;24:89–97. This is an excellent review of sampling variability in liver biopsy. Small biopsies are particularly prone to underestimate the severity of liver injury.

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Lindor KD, Jorgensen RA, Rakela J, et al. The role of ultrasonography and automatic-needle biopsy in outpatient percutaneous liver biopsy. Hepatology 1996;23:1079–1083. Ultrasonographic guidance decreased pain, but not major complications, after percuaneous liver biopsy. Piccinino F, Sagnelli E, Pasquale G, et al. Complications following percutaneous liver biopsy: a multicenter retrospective study on 68,276 biopsies. J Hepatol 1986;2:165–173. This large multicenter study examines the complications of percutaneous liver biopsy. Smith TP, Presson TL, Heneghan MA, et al. Transjugular biopsy of the liver in pediatric and adult patients using an 18-gauge automated core biopsy needle: a retrospective review of 410 consecutive procedures. AJR Am J Roentgenol 2003;180:167–172. The authors report on indications, success, and complications achieved with the use of transjugular liver biopsy in a single center experience. Vargas C, Jeffers LJ, Bernstein D, et al. Diagnostic laparoscopy: a 5-year experience in a hepatology training program. Am J Gastroenterol 1995;90:258–262. This large single center experience shows that diagnostic laparoscopy can be performed safely with a low rate of complications.

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195. Lee RG. Nonalcoholic steatohepatitis: a study of 49 patients. Hum Pathol 1989;20:594–598.

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198. Mofrad P, Contos MJ, Haque M, et al. Clinical and histologic spectrum of nonalcoholic fatty liver disease associated with normal ALT values. Hepatology 2003;37:1286–1292.

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Editors: Title:



Copyright ©2007 Lippincott Williams & Wilkins > Ta bl e o f Co nte nts > Volu me I > Sec tio n I - Overvie w: Cli nic al F unda m enta ls of H epa tolog y > Cha pter 4 - Im a ging

Chapter 4 Imaging Furqaan Ahmed Deirdre Coll Ira M. Jacobson

Key Concepts z

Recent technologic advances have led to considerable improvements in liver imaging.

z

Ultrasonography is a quick, widely available, and inexpensive modality for hepatic imaging and is often the initial imaging test

z

Multidetector computed tomography (CT) scan and magnetic resonance imaging (MRI) allows three-dimensional imaging of the hepatic

ordered. parenchyma and vasculature. z

Evaluation of hepatic malignancies is facilitated by 2-fluoro-deoxy-D-glucose (FDG) positron emission tomography.

z

Ultrasonography, noncontrast CT scan, and magnetic resonance imaging (MRI) are able to demonstrate the presence of hepatic steatosis; however, none of these imaging modalities is able to distinguish between steatosis and steatohepatitis.

z

Ultrasonography with Doppler imaging is a useful first tool for the diagnosis of hepatic venous thrombosis; MRI allows superior visualization of the inferior vena cava and hepatic veins, as well as liver parenchyma.

z

Ultrasound guidance is commonly used for percutaneous liver biopsies in patients with diffuse liver disease. Although studies have suggested that this practice may result in fewer complications, more data are needed before this can be established as a uniform standard.

Noninvasive Imaging of the Liver Recent technological advances have allowed considerable improvement in imaging of the liver. This introductory section provides a short description of the imaging modalities, with brief guidelines on which test to use and when. An in depth explanation of the physics is beyond the scope of this text. The aim is that the referring physician will understand the advantages and limitations of the imaging modalities available. It is hoped that this will facilitate the choice of the most appropriate diagnostic tool for better and more cost-effective patient care. The second portion of the chapter will address selected clinical problems in which critical use of radiologic modalities plays a role in evaluation and management.

Ultrasound This test should serve as a baseline for nearly all patients who initially present with symptoms suggestive of liver or gallbladder disease. It is fast, cost-effective, noninvasive, widely available, and involves no radiation. The basic principle of ultrasound is the transmission of sound waves into the liver from a transducer. These waves reflect at interfaces between tissues with differing acoustic impedance. For example, at the soft tissue–air interface almost total reflection occurs, which explains the use of ultrasound gel to allow the sound waves to pass into the body. As the ultrasound wave passes through the liver, the sound wave is affected by changes in tissue type and is refracted and reflected. The transducer is able to detect the reflected sound waves and uses the time delay from transmission to P.84 calculate depth within the body. The ultrasound image displays the amplitude of reflection as a function of position, with the “whiteness” of the image directly proportional to the amplitude of reflection. The liver is best evaluated with a 2 to 5 MHz ultrasound transducer. In larger patients, the lower frequency permits greater tissue penetration. The higher frequency transducers offer improved spatial resolution but less penetration. Therefore, imaging of superficial structures should be preferentially performed with a higher frequency transducer. The appearance of a lesion within the liver is explained by its relative reflectivity compared with the surrounding liver parenchyma. When the sound wave passes through a structure without any reflection, no echoes are generated and the structure appears black or anechoic, such as a hepatic cyst (Fig. 4.1). When nearly all of the sound wave is reflected, the structure appears white or hyperechoic such that the lesion appears brighter than the liver. This is well demonstrated with a cavernous hemangioma whose classic appearance is that of a homogenously hyperechoic structure (Fig. 4.2). This is secondary to its complex internal structure whose network of vascular structures almost completely reflects the ultrasound beam. When some of the sound waves pass through, and some are reflected, the lesion will be gray or hypoechoic. This means that the lesion is less bright than the liver. An example is colorectal metastases (Fig. 4.3). Tissue harmonic imaging is an alternative method of producing an image. When an ultrasound wave insonates tissues in the body, this produces secondary sound waves at integral multiples of the fundamental transmitted frequencies. Harmonic imaging utilizes these frequencies (generally only the second harmonic or twice the transmitted frequency) to produce an image. These images generally have improved axial resolution due to shorter wavelength, and better lateral resolution due to improved focusing with higher frequencies. They also have fewer artifacts, as the smaller amplitude of the harmonic waves decreases the detection of echoes from multiple scattering events; they also have less reverberation and side lobe artifacts, and increased contrast resolution as compared to standard sonography. This is particularly useful for obese and technically difficult patients. It also provides for a more accurate characterization of cystic lesions. The disadvantages of this technique are that the harmonic echoes are weaker, which can cause a noisier image. They also have less penetration than images obtained with conventional sonography. This technique is P.85 available on most of the latest ultrasound machines (1,2,3).

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▪ Figure 4.1 Simple hepatic cyst (arrow). Note the posterior acoustic enhancement.

▪ Figure 4.2 Hemangioma. Transverse ultrasound image through the left lobe of the liver shows a hyperechoic (arrow) 2 cm hemangioma.

▪ Figure 4.3 Hepatic metastasis. Saggital view through the left lobe of the liver shows four metastatic lesions (arrows) in a patient with metastatic colon cancer.

In conventional sonography, the liver is isonated at a single constant angle. In real-time compound sonography, the image is obtained by combining slices from multiple different angles. As the object is now imaged from multiple spatial orientation and the image is formed from the summation of the individual frames, this results in reduced image artifacts, better delineation of surface noise, and better image contrast to produce a better sonographic image. Limitations include blurring from motion, as the image takes longer to acquire. There is also less posterior acoustic shadowing, which is often a useful artifact when trying to characterize a lesion (4). It is possible to combine compound and harmonic imaging modalities; one study has suggested that this technique will produce images superior to either technique alone (5). Ultrasound specific intravenous contrast agents are intravenous “microbubble” contrast agents that consist of an encapsulating shell material (albumin, phospholipid or polymer) surrounding air or flourocarbon gas. These particles are relatively stable in the bloodstream and highly reflective when isonated by ultrasound at typical frequencies used in medical imaging. In fact, there is linear reflection (at the same frequency as that transmitted by the transducer) and a non linear component of reflection that is useful for harmonic imaging (see the subsequent text). In general, the degree of increased echogenicity in a liver lesion will depend on the relative perfusion of the lesion compared to the liver (thus yielding information similar to a contrast-enhanced computed tomography (CT) scan or magnetic resonance imaging (MRI). These agents have not been approved by the U.S. Food and Drug Administration (FDA) for use in the United States, but they have been used in Europe for the past few years. Contrast-enhanced scans are thought to provide more information than color Doppler alone. Tissue harmonic imaging can detect nonlinear vibrations of microbubble contrast agents and is a fertile area for future research (6). Given the relatively low sensitivity of ultrasound for the detection of liver lesions in patients with parenchymal liver disease, contrast agents offer the potential of bringing ultrasound to a comparable level with CT scan and MRI. A recent study utilizing contrast agents for

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the detection of small hepatocellular carcinoma (HCC) reported sensitivity and specificity rates of 94% and 93%, respectively (7). In contrast, conventional ultrasonography has been reported to have a sensitivity of 74% to 88% for the detection of cirrhosis when liver biopsy and/or gross observation at laparoscopy were used as standards of reference (8,9,10). The reported sensitivity of conventional ultrasonography for the detection of metastatic lesions in the liver is relatively poor (53% to 77%) and is inferior to that of contrast-enhanced CT scan and MRI. Lesions are missed at ultrasound either because they are too small, with the sensitivity for lesions smaller than 1 cm being as low as 20%, or because the lesions are isoechoic with the background tissue and therefore very difficult to perceive. This also explains why it is difficult to detect lesions in cirrhotic and fatty liver. The parenchymal changes in these livers increase the reflectivity and they appear “brighter” on ultrasound and will therefore “hide” lesions, which are of the same echogenicity (11,12,13,14). Color, spectral, and power Doppler imaging provide a noninvasive method of measuring flow in the hepatic blood vessels, and assessing vascularity within a lesion. Spectral Doppler provides a tracing of the Doppler wave from which we can calculate various indices, including peak systolic velocity and resistive indices (Fig. 4.4). In conjunction with the color Doppler, it enables the operator to determine the direction of blood flow. Power Doppler imaging displays the integrated power of the color signal to depict the presence of blood flow. The color Doppler display reflects the mean Doppler frequency shift. Power Doppler is therefore a more sensitive method of demonstrating flow, but does not give any quantitative information about the velocity or the direction of blood flow (15,16). Nearly all ultrasound machines now have, as standard, color and spectral Doppler imaging. It is routine to document the presence or absence of flow, and the direction of flow in the hepatic veins and portal veins (Figs. 4.5 and 4.6). Interrogation of the hepatic artery is not routinely done except when specifically requested, or in a posttransplant patient.

▪ Figure 4.4 Hepatic artery. Spectral Doppler tracing of the right hepatic artery. Peak systolic velocity and minimum diastolic velocity values are used to calculate the resistive index.

▪ Figure 4.5 Portal vein. Spectral Doppler tracing of the left portal vein shows a normal hepatopedal (above the baseline) flow into the liver. It is normally of low velocity with an undulating spectrum.

P.86 There are no absolute contraindications to ultrasonography. Relative contraindications include morbid obesity, in which it is often difficult for the sound waves to penetrate the patient to produce a diagnostic image. Patients with respiratory compromise may not be able to suspend respiration. As discussed in the preceding text, the ultrasound of the liver is limited if the patient has parenchymal disease such as steatosis or cirrhosis. In these patients this limitation should be documented on the radiology report, and if there is persistent suspicion the physician should be aware that a CT scan or an MRI must be performed for further evaluation.

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▪ Figure 4.6 Spectral doppler tracing of the right hepatic vein as it drains into the inferior vena cava. The normal triphasic spectral tracing reflects the pulsatility of the right atrium.

Patients will need to fast for 6 hours to reduce the amount of bowel gas so that the gallbladder and the biliary system can be assessed at the same time. The test, in general, will take approximately 30 minutes, and the patient will be asked to hold their breath repeatedly so the technologist can take images during suspended respiration.

Computed Tomography Just as the introduction of CT scan impacted the detection of liver lesions, recent advances in CT scan have revolutionized the characterization of these lesions. Spiral and helical CT scan are terms that are used interchangeably. Helical CT scan is now performed almost universally, enabling the acquisition of thinner slices with improved spatial resolution more rapidly than conventional CT scan. The difference between helical and conventional CT scan is that spiral scanners are able to continuously rotate the x-ray CT scan tube, while the patient is moved through the scan plane. Therefore, instead of producing single slices, spiral scanners are able to acquire data over a volume of the patient (such as the craniocaudal extent of the liver), while the x-ray CT scan tube is continuously rotated. Early helical scanners were able to rotate 360 degrees in roughly 1 second (1,000 ms gantry rotation) and used a single detector (singleslice CT scan) with a thickness of approximately 1 cm (1 cm spatial resolution). This single axial image was formed by the rotation of a single detector, coordinated with incremental CT scan table advancement and a pencil like CT scan source. The first generation CT scanners took 25 minutes to produce five views of the head. This progressed to a linear row of detectors with a fan beam, to a partial circle of detectors, and finally to the present, in which the patient is moved through the scanner and a helix of raw projection data is generated. Instead of a single row of detectors there are multiple rows of detectors. This is how the term multislice CT scan, originated. Multislice scanners are so named because they have more than one detector (between 2 and 64), and can therefore produce more than one slice per rotation. Currently, slices are as thin as 0.4 mm and can be acquired using gantry rotation times as low as 0.33 seconds (165 ms temporal resolution). Most facilities now have helical CT scan available to them. At the time of writing, many facilities have 64 row scanners and there are plans to have up to 125 rows, followed eventually by volumetric scanning. These scanners allow images to be produced more quickly: For example, with a 16-row scanner we can scan the patient from head to toe in less than a minute. Therefore, we can scan through the P.87 entire liver in less than 10 seconds, which allows scanning in multiple phases of enhancement, and also lessens the problems of respiratory artifact. These scanners can take thinner slices through the liver—with 0.625 mm slices; this allows almost isometric imaging (voxels of identical dimensions in all three planes) and exquisite three-dimensional (3D) images. These advantages also permit more advanced image processing, such as digital subtraction and CT scan perfusion (17,18). Nearly all facilities now have helical scanners and can scan through the liver in multiple phases. 3D and CT angiography can be routinely performed. While 3D is not needed routinely for the assessment of a liver lesion, 3D imaging and CT angiography are very helpful in identifying the location of the lesion for the surgeon and for vascular mapping, and should be considered for patients who are candidates for surgery. (Figs. 4.7 and 4.8). CT angiography is now routinely used for the preoperative work up of living related donors for partial hepatectomy. This also allows liver volume estimation before surgery (Fig. 4.9). In summary, the development of multidetector CT scan has greatly advanced the image quality of hepatic imaging. CT scan offers the highest spatial and temporal resolution, allowing advanced applications and very high quality 3D imaging of both the parenchyma and hepatic vasculature. CT scan should be considered as the first option in older patients for whom radiation is not a concern. In particular, elderly patients who will have difficulty holding their breath will usually do better with CT scan than with MRI. For a dedicated examination of the liver, patients need to fast for 6 hours. This has a twofold advantage; the gallbladder is distended which allows a better evaluation, and the patient has an empty stomach, which will reduce the risk of any vomiting post injection of intravenous contrast. There is usually no need to drink oral contrast for a dedicated hepatic CT scan, unless there is some reason to evaluate the bowel also. For an examination targeted to the biliary system, many centers are now advocating that the patient drinks a liter of water prior to the scan. This distends the bowel and helps to trace the course of the common bile duct P.88 as it passes into the duodenum. For most examinations of the liver, patients will get an intravenous cannula inserted in their arm. The actual scanning time is approximately 5 minutes, but the patient should expect to be within the radiology department for about an hour. Most patients are observed for approximately 20 minutes for postcontrast reactions. If they have a history of allergy, they will need to be premedicated or an MRI scan considered.

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▪ Figure 4.7 3D volume rendering of a liver with a small hepatocellular carcinoma in the right lobe (arrow). The computed tomography angiogram provides exquisite detail of the segmental branch of the right hepatic artery, which is supplying the tumor. This provides the surgeon with a clear road map to enable accurate preoperative planning.

▪ Figure 4.8 3D volume rendering of the same patient (fig. 4.7) now showing the relationship of the portal venous system to the tumor in the right hepatic lobe.

▪ Figure 4.9 3D volume rendering of the liver. The contour of the liver is traced on individual axial slices and then summed to give an accurate estimation of liver volume.

Relative contraindications include pregnancy, allergy to iodinated dye, renal failure, and patients with end stage cirrhosis who are at risk for hepatorenal syndrome.

Radiation There has been much concern about radiation dose with CT imaging. If all medical x-ray imaging modalities are analyzed, CT scan accounts for 40% to 67% of the radiation dose, but only 5% of the number of tests ordered. The number of CT scan examinations being performed is increasing every year (19). Most of this concern is focused on the pediatric and younger populations, which are most sensitive to radiation. However, both the radiologist and the ordering physician should be aware of the radiation dose. The unit for assessing the risk of cancer from a CT scan is the “effective dose” which is measured in millisieverts (mSv; 1 mSv = 1 mGy in the case of x-rays.) Effective dose allows comparison of the risk estimates associated with partial or whole-body radiation exposures. It

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also incorporates the different radiation sensitivities of the various organs in the body. The actual effective dose from a CT scan can vary by a factor of 10 or more depending on the type of CT scanner, the protocol (how many phases, kVP, mAs etc.) and patient weight. Table 4.1 shows a list of radiology tests and their associated doses taken from a report of the European Commission (20). The reduction of the dose in general requires lowering mAs and kVp and increasing pitch. Therefore, there is always a trade-off between the image quality and the dose. Most radiology departments have dose reduction policies in place, particularly for the pediatric population (21).

Nephrotoxicity The field of contrast usage has progressed from high osmolar contrast agents (osmolality five times higher than that of serum) to low osmolar contrast agents twice the osmolality of serum, and finally to iso-osmolar (290 mOsm/L) agents, which are almost isotonic with blood. They have been reported to have less nephrotoxic effects than the other contrast agents (22). Other approaches to reducing contrast induce nephropathy (CIN) have been the use of N-acetylcysteine. This has the advantage of being inexpensive, safe, and is widely used. Although, not all studies have shown a definite benefit, the use of N-acetylcysteine has become routine in many centers for patients with renal insufficiency. (23,24).

Computed tomography perfusion The basis of CT scan perfusion is that it detects the difference between regional and global alteration in blood flow. It was initially developed in the brain to try to quantify blood flow for patients with a cerebrovascular accident. The ability to distinguish between arterial and portal venous phase on a global and regional basis imaging provide the basis for CT scan perfusion of the liver. In order to perform this technique, the purchase of a separate software package is required. Perfusion measurement is the blood volume divided by time divided by tissue volume. For example, there is a relative increase in arterial versus portal venous flow in cirrhosis, offering potential for the early noninvasive detection of cirrhosis, but this remains to be proven. A similar rationale exists to offer the hope of earlier detection of HCC and metastatic disease. Dose considerations means that this technique is not yet feasible for these options (25). The technique of CT scan perfusion remains investigational, and is not available on a routine basis.

Positron Emission Tomography and Computed Tomography–Positron Emission Tomography Positron emission tomography (PET) is a functional imaging modality. It utilizes positron emitters such as fluorine-18, oxygen-15, nitrogen13 and carbon-11. However, all of the above except fluorine have very short half-lives, which means that an on site cyclotron would be required. Therefore, this discussion will be limited to the use of fluorine-18 which is widely available as 2-fluoro-deoxy-D-glucose (FDG). FDG has a half-life of 110 minutes and has high uptake in most cancers. FDG-PET is based on the principle that there is increased glucose metabolism seen in malignant tissue relative to that of the surrounding normal tissue, and that this increase in metabolism is seen as a more intense uptake on FDG-PET images (Fig. 4.10). FDG competes with glucose for transport into a cell. Inside the cell, like glucose, FDG is phosphorylated by hexokinase into FDG-6-phosphate. In normal liver cells, there is a high concentration of glucose-6-phosphatase, which causes dephosphorylation and allows it to exit from the cells. Therefore, in the healthy patient there is rapid clearance of FDG from the liver. In malignant cells the up regulation of hexokinase causes increased glucose utilization (26). P.89 These cells often have decreased glucose-6-phosphatase, and the FDG remains trapped within the cell (27,28,29). Increased FDG uptake is, however, nonspecific and may occur in any condition associated with increased tissue metabolism. This accounts for the uptake seen in acute or chronic inflammatory or infectious processes (30).

▪ Figure 4.10 Normal positron emission tomography scan of the body demonstrating the normal uptake in the liver (arrow).

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▪ Figure 4.11 Positron emission tomography–computed tomography scan of a patient with multiple colorectal metastases. The dominant lesion in the right lobe of the liver is marked on both images (arrows).

PET–CT scan combines the cross-sectional anatomic information from CT scan with the functional information acquired by PET. They are both acquired during a single examination and fused. The ability to fuse information from both studies allows the accurate localization of increased FDG activity to specific anatomic locations. This is often difficult with PET alone (31).

Hepatic metastatic disease Studies utilizing PET have shown encouraging results when evaluating patients for metastatic liver disease. In studies of patients with a known solitary hepatic metastasis identified on conventional imaging, PET can detect other lesions. This is of particular importance in this patient population, as it may radically change patient management (32,33,34). In a meta-analysis of the literature on colorectal liver metastases from January 1990 to December 2003, sensitivity estimates on a perpatient basis for helical CT scan, 1.5-T MRI, and FDG-PET were 64.7%, 75.8%, and 94.6%, respectively. On a per-lesion basis, sensitivity estimates for helical CT scan, 1.0-T MRI, 1.5-T MRI, and FDG-PET were 63.8%, 66.1%, 64.4%, and 75.9%, respectively. Therefore, FDGPET had significantly higher sensitivity on a per-patient basis, compared with that of the other modalities, but not on a per-lesion basis (35). A meta-analysis looking at noninvasive imaging methods for the detection of hepatic metastases from colorectal, gastric, and esophageal cancers found that at equivalent specificity, FDG-PET is the most sensitive noninvasive imaging modality for the diagnosis of hepatic metastases from colorectal, gastric, and esophageal cancers (Fig. 4.11) (36). P.90 False-negative FDG-PET can occur secondary to physiologic movements of the liver, infectious/inflammatory foci, underestimation of uptake, and recent completion of chemotherapy or radiotherapy. PET has demonstrated a high sensitivity for detection of disease when the lesions are larger than 1cm. As it does not reliably detect tumors less than 1 cm, it is suggested that PET-CT scan offers the patient the benefit of both imaging modalities (37,38). Most of the work on hepatic metastases has focused on patients with colorectal carcinoma. One of the major advantages of PET is also the ability to survey the whole body for metastatic disease. Studies suggest that when PET is added to CT scan in preoperative planning for patients with hepatic metastases, additional sites of extrahepatic disease are identified in 11% to 23% of patients. This has had significant clinical impact in the management of these patients (39,40).

▪ Figure 4.12 A: Positron emission tomography–computed tomography (PET–CT) scan of a multifocal highly aggressive hepatocellular carcinoma. The PET scan shows the extent of the disease. B: In the same patient, images through the sacrum show a metastatic bone lesion in the right ileum. The PET–CT scan can help to detect unsuspected metastatic disease.

Hepatocellular carcinoma HCC has a low uptake of FDG. Consequently, the detection rate of PET scans for HCC is approximately 50% (41,42). The uptake of FDG appears to correlate with the degree of differentiation of the HCC (Figs. 4.12A,B). Poorly differentiated tumors have greater uptake of FDG than well-differentiated tumors. This is thought to be due to the fact that in well-differentiated HCC, there is a high intracellular concentration of glucose-6-phosphatase so that well-differentiated HCC and normal hepatocytes metabolize glucose-6-phosphate and FDG at the same rate (43). Also, glucose transporters do not seem to be overexpressed in HCC as often as in other malignancies (44). 11-C acetate is a newer PET tracer with a half-life of 20 minutes. Therefore, an on site cyclotron would be required to utilize this tracer. In contrast to FDG, it

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P.91 is taken up in well-differentiated HCCs, but it cannot detect poorly differentiated HCCs (45). Recent studies have suggested that the delayed imaging of the liver at 2 to 3 hours may offer improved results for the detection of HCC. This is thought to be due to a gradual increase in uptake in FDG by the tumor, and decreased uptake by the hepatocytes. In summary, FDG should not be used for the routine detection of HCC. FDG uptake depends on the histological grading of the tumor and is highest in the poorly differentiated tumors, whereas 11-C acetate uptake is better for the well-differentiated tumors. Delayed scans post injection may offer a better sensitivity.

Cholangiocarcinoma The largest study (31 patients) looking at the use of PET for the detection of cholangiocarcinoma showed a sensitivity of 61% and a specificity of 80%. It showed a better sensitivity for nodular than infiltrating lesions. Care must be exercised in patients with biliary stents as they can cause a false-positive reading. Acute inflammation in patients with sclerosing cholangitis can also cause a false-positive reading. The authors suggest that PET is accurate in predicting the presence of nodular cholangiocarcinoma (mass >1 cm) but is not helpful for the infiltrating type (46). Other studies have shown decreased sensitivity for the detection of mucinous tumors (47,48). Hilar and extrahepatic cholangiocarcinoma are less intense on FDG-PET than peripheral cholangiocarcinoma (49,50). The use of standardized uptake values for evaluating the uptake of FDG shows promising results in trying to distinguish between extra hepatic bile ducts malignant and benign strictures (51). In summary, it appears that if cholangiocarcinoma has sufficient tumor volume, it will take up FDG-PET. It is not sensitive for mucin containing tumors and will have false-positive results for those patients with inflammatory conditions such as sclerosing cholangitis.

Radiation dose One study has reported the effective dose per PET–CT scans examination at or about 25 mSv. Please see Table 4.1 for comparison to other examinations (52,53,54).

Patient information Although each center will have its own specific procedures, the following are general guidelines. The PET scan and the CT scan will be performed during a single visit. Patients should fast for at least 4 to 6 hours prior to their scan. They will receive an intravenous injection of 18FDG, following which there is usually a wait of about an hour for the FDG to distribute throughout the body. The patient is then taken to the scanner. The CT portion of the scan is usually completed first. This will take only approximately 5 minutes. Depending on the part of the body being imaged, patients may receive another injection at this stage of radiographic contrast. Intravenous radiographic contrast is not used routinely at present. On the same imaging table, the PET portion of the scan is then performed. This may take up to 45 minutes.

Table 4.1. Typical Effective Doses of Ionizing Radiation from Common Imaging Procedures (20)

Class

Typical effective dose (mSv)

Examples

0

0

I

10

PET studies

US, MRI

US, ultrasonography; MRI, magnetic resonance imaging; IVU, intravenous urogram; CT, computed tomography; PET, positron emission tomography.

If the blood sugar is elevated over 200 mg/dL, the scan will be postponed. All diabetic patients must have their blood sugar levels regulated. Insulin should not be injected near the time of the scan, as it will cause increased uptake in the local skeletal musculature. It is recommended that FDG-PET be performed in the morning after an overnight fast. The patient should not exercise for 24 hours prior to the scan. The patient's bladder should be emptied prior to the scan. The patient should be asked about recent surgery, active inflammation, or infection.

Magnetic Resonance Imaging State of the art MRI of the liver is now routinely performed with a torso phased array coil. This is a surface coil placed on the patient which provides a better image by allowing a greater signal-to-noise ratio. Stronger magnets and improved software now allow imaging of the entire liver in one breathhold. Multiple sequences are performed in a routine liver MRI. These sequences should include T1, T2, in-and outof-phase images, and pre– and post–dynamic contrast images. The pre- and post contrast sequence can be performed either with standard 2 dimensional axial sequences, or a 3D volume acquisition. The advantages of MRI are the lack of radiation and the use of non-nephrotoxic contrast material. It offers higher contrast resolution but decreased spatial resolution when compared to CT scan. Nearly all liver P.92 examinations require administration of contrast. However for an MRCP, no contrast is given. Therefore, if the sole goal of the test is to evaluate the bile ducts for calculus disease, contrast is not required. However, if a simultaneous evalution of the pancreas or liver parenchyma is desired, or if there is any concern about malignancy, the study will require dynamic administration of intravenous contrast. MRI is the test of choice for the noninvasive quantification of liver iron. The presence of iron causes a decrease in the MRI signal intensity causing the liver to appear dark. This is caused by a decrease in the T2 relaxation rate of protons. Other limitations are that the amount of fibrosis and inflammation in the liver can affect liver iron measurements (55).

Contrast agents The vast majority of liver MRI is performed with gadolinium chelate contrast agents, which have characteristics similar to the contrast agents used for CT scan examinations. Newer contrast agents are liver targeted. The three different types of contrast agents are nonspecific gadolinium chelates, reticuloendothelial system specific agents, and hepatocellular-specific agents. Nonspecific gadolinium chelates are the contrast agents routinely used in liver MRI examination. They are nonspecific extracellular

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gadolinium chelates. It is a paramagnetic substance, which causes increased signal in tissue on the post injection T1-weighted images. The agent initially distributes in the intravascular compartment, and then diffuses into the extracellular space. This enables the characterization of the tumor vascularity. It is safe, relatively low cost, and has good patient tolerance. Iron oxide particles are taken up into the reticuloendothelial system (RES). In the liver, they are taken up by the Kupffer cells. Reticuloendothelial system specific agents (superparamagentic iron oxide particles) are administered as a slow infusion over 30 minutes. The most common side effects are hypotension and lumbar pain. Most focal liver lesions lack Kupffer cells. The normal liver will appear dark on T2-weighted images due to the normal uptake of the particles—thereby increasing sensitivity for the detection of focal liver lesions (Fig. 4.13). The lesions cannot be characterized as benign or malignant (56). Newer agents with ultra small iron oxide particles also offer dynamic imaging as they are taken up more quickly into the Kupffer cells. They offer the possibility of characterization of lesions, as lesions containing Kupffer cells will take up the contrast agent (57). Hepatocellular-specific agents, including newer agents such as mangafodipir trisodium, are administered by slow infusion, accumulate in hepatocytes, and are excreted by the biliary system. This causes an enhancement of the liver parenchyma, but not of masses of nonhepatocytic origin. This may lead to greater detection of lesions. This has been shown to be most useful when assessing patients with liver metastases to determine if they are viable surgical candidates. It does not, however, help to characterize the lesion as benign or malignant. As HCCs contain hepatocytes; these agents are not useful for the detection of HCC. It has also been postulated for use to evaluate the biliary system, such as for the detection of biliary leaks (58,59,60,61).

▪ Figure 4.13 T2-weighted axial image through the liver shows a left lobe hemangioma in a patient who has received ferridex. Note the low signal intensity of the liver.

Combinations of perfusion and hepatocellular agents combine the properties of a conventional extracellular contrast agent with those of a liver specific contrast agent: Examples of these agents are gadobenate dimeglumine (Multihance Bracco Diagnostics, Princeton, New Jersey) and gadoxetic acid disodium (Eovist Schering, Berlin, Germany). They are initially distributed in the vascular interstitial compartment like the normal extracellular gadolinium chelate contrast agents, and then a percentage is taken up into the hepatocytes in a delayed fashion. Therefore, they can offer both dynamic characterization and the opportunity for increased liver lesion detection (62,63,64).

Summary Characterization of liver lesions with standard extracellular contrast agents remains the standard of care in the United States. In Europe, however, the use of liver specific contrast agents now offer the possibility of a one-stop test to evaluate focal liver lesions. A dedicated liver MRI examination will require at least 30 minutes in the magnet. This involves multiple breath holds. It is a much longer examination than a CT scan of the liver. This is often stressful for elderly patients or patients with a large amount of ascites P.93 who are unable to successfully suspend respiration for 20 to 30 seconds in a repetitive fashion for this time period. In these patients a CT examination should be considered. However for the younger patient where radiation is a concern, or where there are renal problems, MRI is the test of choice. Nearly all patients will require an intravenous injection. This is approximately 20 mL, plus a saline flush of a gadolinium based contrast material. The bore of the magnet is relatively small but most patients, unless claustrophobic, tolerate the examination. The presence of a pacemaker or ferromagnetic materials in a patient is a contraindication to performing an MRI.

Selected Clinical Problems Nonalcoholic Fatty Liver Disease Exceeding by a wide margin the prevalence of any other liver disease, nonalcoholic fatty liver disease (NAFLD) occurs in about 20% of people in the United States. In recent years, increasing evidence has accumulated supporting the potential for NAFLD to cause progressive hepatic fibrosis with all its attendant complications (65), including HCC. A distinction has been made between steatosis alone, which appears to have a relatively benign prognosis and is the more prevalent of the two variants of NAFLD and nonalcoholic steatohepatitis (NASH), which is the variant that carries greater potential for progressive fibrosis (66,67). Thus, distinguishing between steatosis and steatohepatitis is a key component of the evaluation of patients with NAFLD. One of the leading dilemmas faced by clinicians in evaluating patients with suspected NAFLD is the role of liver biopsy. A consensus that liver biopsy is required for all patients with this disorder would lead to a marked increase in the number of biopsies and would possibly be unrealistic in terms of the available resources. Imaging has the potential to play a critical role in the management of such patients. Among the leading questions are the following: (i) What is the sensitivity and specificity of imaging in the diagnosis of NAFLD in patients with elevated liver enzymes who have no evidence of other liver diseases? (ii) Can imaging be used to distinguish steatosis from steatohepatitis? (iii) To the extent that imaging has a role, which imaging modality is most useful? (iv) Can imaging be used to follow patient response to therapeutic interventions? These questions will be considered in the discussion that follows.

Detection of fatty liver by imaging On ultrasound, fatty liver can be recognized by several characteristics, including increased parenchymal echogenicity, or a bright echo pattern which accentuates a normally inconspicuous difference between the liver and the renal cortex or the spleen (Fig. 4.14) (68); increased attenuation of the ultrasound beam, causing posterior darkness and loss of definition of the diaphragm; and loss of intrahepatic architectural detail producing loss of definition of the portal veins (68). The loss of portal vein definition occurs because the fat normally surrounding the portal veins, which usually offsets the veins from the parenchyma, now has the same echogenicity as the liver. The increased echogenicity caused by fibrosis has led to the term “fibrofatty pattern” (69). The nonspecificity of this pattern in distinguishing fibrosis from fat is one of the limiting features in the use of ultrasound for fatty liver disease. Furthermore, increased hepatic echogenicity is not specific for hepatic steatosis and may be seen in other diffuse liver diseases. Attempts to grade the severity of steatosis using

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ultrasound criteria are limited by the generally broad categories described, and by the operator dependency of the technique and differences due to ultrasound settings used (69,70).

▪ Figure 4.14 Fatty liver. Ultrasound image shows an echogenic, attenuating liver.

The accuracy of CT scan in detecting fatty liver is greatest with noncontrast studies. Contrast-enhanced CT scan is less accurate for the diagnosis of hepatic fat deposition because of the varying densities of the liver and spleen on these images, and the interference of the contrast with fat detection (71). In contrast to sound waves, fatty liver results in the decreased attenuation of x-rays, resulting in a darker appearance than normal and, in a reversal of the usual pattern, a liver which is darker than spleen. Fatty liver is diagnosed on CT scan if the liver attenuation is less than 40 Hounsfield units or a relative attenuation of 10 Hounsfield units less than the spleen (Fig. 4.15). The spleen is used as the reference organ as it does not accumulate fat (72,73).

▪ Figure 4.15 Fatty liver. Computed tomographic scan shows diffuse low attenuation to the liver consistent with fatty infiltration.

P.94 Other diffuse liver diseases, including acute hepatitis, may also cause decreased hepatic attenuation. There is a relationship between the degree of hepatic steatosis and CT scan density but, as for sonography, a reliable distinction of steatosis from steatohepatitis cannot be made with CT scan, nor can the degree of fibrosis be reliably assessed (68,74,75). Although the radiation exposure with CT scan places practical limits on the widespread use of serial assessments for hepatic steatosis with this technique, some studies have used serial CT scan for assessing the response of hepatic steatosis to therapy (76). MRI quantifies the fat content of the liver by chemical shift imaging, which takes advantage of the difference in resonant frequencies between protons in a fat and water environment. A recent study has described the successful quantitation of hepatic fat morphology and the severity of steatosis with MRI (77). Chemical shift imaging is not confounded by the presence of hepatic fibrosis (77). The liver is imaged on a T1-weighted gradient dual echo sequence using both “in-phase” and “out-of-phase” images. In steatosis there is a decrease in the MR signal intensity on the “out-of-phase” images. Comparison is performed with the spleen, which does not usually accumulate fat. However, the spleen can accumulate iron, which will cause the signal intensity to decrease. In this situation, the skeletal muscle or the kidney may provide a more accurate comparison for the assessment of changes in hepatic signal intensity. Magnetic resonance spectroscopy (MRS) allows the quantitation of hepatic fat that can be used for serial estimations without the radiation exposure of CT scan. Studies in patients with both alcoholic and nonalcoholic fatty liver disease have reported accurate measurements of hepatic fat deposition with this technique (78,79).

Performance characteristics of imaging modalities In a recent analysis of the literature, the sensitivity of ultrasound for recognizing fat in the liver ranged from 60% to 89%, and the specificity was 84% to 95%. The positive predictive value for an ultrasound suggesting fatty liver was 96%, while an ultrasound not demonstrating fatty liver was associated with a 19% chance of fatty liver being present (68). The ultrasound criteria for the determination of fatty liver has varied in these published studies with some requiring only increased hepatic echogenicity (without comparison with the echogenicity of other organs) for diagnosis. More strict criteria for the ultrasound diagnosis of steatosis and more severe degrees of steatosis result in improved performance characteristics (70,80). A study of 187 morbidly obese patients compared ultrasonography with liver histopathology from liver biopsies done at the time of bariatric surgery. In this patient population, the sensitivity, specificity, and positive predictive value for ultrasound in detecting hepatic steatosis was 49%, 75%, and 95%, respectively (81). On CT scan there is a good inverse correlation between the degree of steatosis and CT scan density scores (68). In a series of 25 consecutive patients with biopsy-proven steatosis undergoing sonography, CT scan and MRI, the presence of greater than 33% fat on liver biopsy was optimal for detecting steatosis on radiological imaging (82). Ultrasound and CT scan were 100% and 93% sensitive in detecting greater than 33% fat, with positive predictive values of 62% and 76% respectively. The degree of intraobserver and interobserver

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agreement was best for MRI, but none of the modalities were able to distinguish steatosis from steatohepatitis, leading to the authors' conclusion that liver biopsy remains the “gold standard.” In a direct comparison of MRI with ultrasound, MRI was more sensitive than ultrasound in detecting relatively small degrees of steatosis, and correlated better with microscopic fat content. MRI correlated better with macrovesicular steatosis than mixed macrovesicular and microvesicular steatosis. Unlike ultrasound, with which several patients with severe fibrosis were misinterpreted to have severe steatosis despite low levels of hepatic fat content on biopsy, MRI was not influenced by the presence of fibrosis (77). A combination of proton

1

H MRS and total body MRI was studied in 11 subjects with biopsy-proven hepatic steatosis and in 23 healthy

volunteers (83). Intrahepatocellular lipid signals were detectable in all subjects but were significantly greater in hepatic steatosis than in healthy volunteers, and were greater in overweight than in lean subjects. In addition to the relationship between hepatic fat content and total P.95 body fat as a percentage of body weight, the strongest correlation was between central obesity and hepatic fat content. The authors proposed that a combination of their technique with

31

P MRS, which reflects cell membrane turnover and fibrosis, might in the future help

resolve the current limitations of noninvasive imaging modalities in distinguishing steatosis from steatohepatitis with fibrosis (83).

Role of imaging in practice Hepatic imaging has a limited but useful role in the evaluation of patients with unexplained liver enzyme abnormalities. If the history and serologic tests are negative for evidence of alcohol, hepatotoxic drugs, toxins or viral, genetic, and autoimmune liver diseases, an ultrasound revealing an echogenic liver or other characteristics of fatty liver disease strongly implies NAFLD or NASH—particularly if there is no clinical, physical, or laboratory evidence of advanced fibrosis, which may confound the interpretation of ultrasound for steatosis. At that point, the decision as to how to proceed depends upon the therapeutic options perceived to be available. If the liver enzyme abnormalities are mild and without evidence of hepatic functional compromise, the patient appears well, and there are noninvasive avenues available for intervention (e.g., overweight status, modest alcohol consumption, or hyperlipidemia) it is reasonable to address these issues for a period of time and observe the effect on the liver tests. If there are worrisome clinical or laboratory features, or if noninvasive approaches have been exhausted, a liver biopsy to distinguish steatosis from steatohepatitis is appropriate. Since all imaging modalities are limited by the inability to distinguish steatosis from steatohepatitis, the threshold for proceeding to biopsy will vary among clinicians and their therapeutic approach to patients with fatty liver disease, especially steatohepatitis. For example, the frequency of liver biopsy to assess for NASH is likely to depend substantially upon the evolving evidence that specific treatments for steatohepatitis, for example, insulin-sensitizing drugs, are effective, and whether in the next several years such agents will continue to be investigational, or are officially approved for such use. With the increased understanding of the pathophysiology of fatty liver disease, it is highly likely that additional new treatments will be developed, leading to a greater reliance upon liver biopsy when there are clinical and/or radiologic findings suggesting hepatic steatosis. On the other hand, it is hoped that there will be progress in combining imaging with serum markers, such as fibrosis assays, that will help make the distinction between steatosis and steatohepatitis, a trend that would further entrench imaging in a central role in the evaluation of these patients. If a patient with unexplained liver test abnormalities has no evidence of steatosis on ultrasound, there is still a potential role for liver biopsy, since the positive predictive value of steatosis on sonography is greater than the negative predictive value. However, negative imaging in the setting of unexplained liver disease increases the suspicion for other liver diseases, and may therefore provide an additional impetus for liver biopsy. With further research and experience MRI, possibly in association with MRS as suggested in the preceding text, may play an increasing role given its capacity to detect smaller amounts of hepatic fat than ultrasound.

Impact of fatty liver on accuracy of hepatic imaging It is now widely accepted that patients with cirrhosis from a variety of causes, including hepatitis B, hepatitis C, hemochromatosis, alcoholic liver disease, nonalcoholic fatty liver disease, α 1 -antitrypsin deficiency, primary biliary cirrhosis, and others, should undergo noninvasive hepatic imaging periodically to screen for evidence of early HCC. Although data from prospective controlled trials are limited, there is near unanimity among hepatologists and surgeons that early detection does favorably impact upon prognosis. Indeed, the presence of HCC increases the Model for End-Stage Liver Disease (MELD) score substantially, propelling the patient forward on the transplant waiting list. From a cost-effective viewpoint, ultrasound is generally used as the most common hepatic imaging modality for HCC screening, and is combined with periodic determination of serum α-fetoprotein level. However, as is discussed in a separate section, ultrasound is not as sensitive as MRI with gadolinium or CT scan with intravenous contrast, raising the question of when one of the other modalities should be used. The situation in which ultrasound suffers the greatest decrement in relative sensitivity is in patients with fatty liver or in obese patients. Accordingly, some clinicians resort to MRI or CT scan for HCC screening in such patients. It is a matter of clinical judgement how frequently one of the alternative techniques should be obtained relative to ultrasound. When cost is not an issue, an argument can be made for exclusive reliance upon CT scan and/or MRI, bypassing ultrasound completely, particularly when the radiologist explicitly points out in an ultrasound report that sonographic visualization of the liver was limited. Another approach, when the ultrasound images are satisfactory but suboptimal, is to alternate CT scan or MRI with sonography such that one or the other is done every 6 months on a rotating basis. At present, however, periodic ultrasound remains an accepted standard. When the other imaging modalities are incorporated into a surveillance program, an P.96 MRI has the advantage over CT of avoiding repeating doses of ionizing radiation over what may prove to be a long period of time.

Focal fat sparing and focal fat infiltration Although hepatic fat deposition often occurs fairly uniformly throughout the liver, focal fat deposition or focal sparing of an otherwise fatty liver are not uncommon, and result from aberrant blood supply. These conditions may cause diagnostic confusion by raising the possibility of a focal neoplastic lesion. Focal fat sparing is thought to occur because of gastric venous or other aberrant blood flow into the affected area, instead of blood flow from the portal system, with its lipid-rich blood supply. Common areas affected by focal fat sparing include the medial segment of the left lobe of the liver, adjacent to the gallbladder fossa, and the porta hepatis. These areas appear hypoechoic on ultrasound and hyperdense on CT scan in comparison with the rest of the fat infiltrated liver (Fig. 4.16). Focal fatty infiltration occurs as a result of excess triglyceride deposition. These areas appear hyperechoic on ultrasound and hypodense on CT scan (Fig. 4.17). Common locations for focal hepatic steatosis include liver tissue adjacent to the falciform ligament, gallbladder or liver capsule, and the medial segment of the left lobe of the liver. In some instances, an area of increased fat deposition in an underlying fatty liver may also give the appearance of a focal lesion. Focal fat deposition is sometimes multifocal, mimicking metastatic disease. Chemical shift MRI using T1-weighted gradient echo sequences is useful in this situation (84).

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▪ Figure 4.16 Focal fatty sparing. Ultrasound image shows hypoechoic apparent mass (arrow) in a patient with hyperechoic fatty liver. Subsequent magnetic resonance imaging confirmed the presence of focal sparing from fatty liver.

▪ Figure 4.17 Focal fatty liver. Ultrasound scan shows a focal echogenic mass (arrow) confirmed with magnetic resonance imaging to represent focal fatty liver.

Areas with either focal fatty sparing or deposition occur in typical locations, have sharply demarcated boundaries, angular margins, and do not exhibit a mass effect or vascular involvement, allowing differentiation from neoplastic and other lesions.

Imaging for Hepatic Iron Overload Determination of hepatic iron status is important for the diagnosis of iron overload, to help decision making on whether treatment is needed, and to help determine response to therapy. The gold standard for hepatic iron determination is a liver biopsy, which can quantify the amount of iron in the liver. However, this test has limitations, including its invasive nature with the risk of significant complications. Variability in measured hepatic iron from small liver biopsy tissue samples, and in patients with cirrhosis, may also limit the usefulness of information gathered from this test. Therefore, noninvasive methods to assess hepatic iron are needed. CT scan has been investigated, but the most promising imaging techniques are MRI and magnetic susceptibility measurements.

Computed tomography On CT scan, hepatic iron deposition results in an increase in liver density, usually measuring between 70 and 130 Hounsfield units (85). This appearance of the liver is a consequence of increased x-ray density due to greater density of iron compared with normal liver tissue (Fig. 4.18). However, a normal attenuation does not exclude hepatic iron overload. CT scan will P.97 generally not demonstrate an attenuation difference until there is five times more than the normal iron contrast.

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▪ Figure 4.18 Hemochromatosis. Nonenhanced computed tomography demonstrates diffuse hyperattenuation of the liver parenchyma secondary to increased iron stores within the liver.

Guyader et al. compared 46 patients with hemochromatosis with 32 patients with chronic liver disease, and 22 controls using hepatic iron quantification as the reference method. Despite a high specificity (96%), the measurement of hepatic density on CT scan had a low sensitivity (63%) (86). In this study, CT scan did not detect iron overload in 14 of 18 patients with low and moderate hepatic iron overload (liver iron concentration 10 ng/mL) and ultrasonography resulted in higher sensitivity (100%) than either ultrasound (87%) or AFP (75%) alone (250). In the single prospective randomized controlled trial of HCC screening 18,816 patients with chronic hepatitis B in Shanghai, China were randomized to undergo screening with both AFP and ultrasound on a 6-monthly basis, or no screening at all (251). Over an approximately 5-year period, patients were offered screening five to ten times; 58% of screening opportunities were accepted. In the screening group, the number of HCC lesions identified and resected was 86 and 40 (47%) versus 67 and 5 (8%) in the control group. In patients with HCC, the 5-year survival rate was 46% in the screening group versus zero in the control group. In this study, bi annual screening reduced HCC mortality by 37%.

Computed tomography (CT) The classical appearance of a HCC on a dynamic CT scan of the liver is that of early arterial phase enhancement, followed by rapid washout on a later phase. A pseudocapsule if present generally shows delayed enhancement. Small well-differentiated lesions may be P.114 P.115 P.116 P.117 P.118 more difficult to detect because of a tendency to have similar attenuation than the surrounding liver tissue. This may be partially overcome by triple-phase CT scan where images are taken in the arterial, portal venous, and the delayed or equilibrium phases. In this type of imaging, the portal venous and delayed phase sequences are useful in identifying small, well-differentiated lesions (Fig. 4.39).

Table 4.2. Performance Characteristics of α-Fetoprotein for Hepatocellular Carcinoma Screening

Mean Number

followScreening

up

AFP

Sensitivity

Specificity

Population

Study design

frequency

(range)

HCC

cutoff

(%)

(%)

Cirrhotics

Retrospective

6 m

NA

19

≥20

58

91

≥50

47

96

>20

63

80

>50

51

89

>100

41

97

>200

32

100

of Study Gambarin-

patients 106

Gelwan (220)

Nguyen

312

(221)

Peng (222)

HCV

Retrospective

NA

NA

163

cirrhotics

205

Chronic

Retrospective

NA

NA

205

>20

65

87

Retrospective

NA

NA

74

>20

55

88

Retrospective

NA

NA

170

>20

60

91

>100

31

99

>200

22

99

>400

17

99

hepatitis C

Cedrone

350

(223)

Chronic viral hepatitis

Trevisani

340

(224)

Chronic viral hepatitis

HCV, hepatitis C virus.

Table 4.3. Performance Characteristics of α-Fetoprotein for Hepatocellular Carcinoma Screening Based on Prospective Studies

Number

Mean

of Study

&u&

patients

Population

Study

Screening

follow-up

design

frequency

(range)

HCC

AFP

Sensitivity

Specificity

cutoff

(%)

(%)

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Sherman

1,069

HBsAg +ve

Prospective

6 m

26 m (6–

(225)

Oka (227)

Chalasani

260

Cirrhotics

285

Cirrhotics

Prospective

2 m

Prospective

30 m

6 m

15 m (6–

(228)

Tong

11

>20

64

91

55

≥20

39

76

≥100

13

97

>20

63

87

>100

41

97

>200

27

100

60 m)

27

42 m)

602

Chronic

(231)

Prospective

6 m

7 y

31

≥21

41

94

Prospective

6 m

56 m (6–

61

>20

41

82

257

>20

55

87

14

>15

50

86

>100

21

93

viral hepatitis

Bolondi

313

Cirrhotics

(229)

Chen JG

100 m)

3,712

HBsAg +ve

Prospective

6 m

62 m

Cirrhotics

Prospective

6 m

36 m (4–

(226)

Pateron

118

(230)

48 m)

Table 4.4. Performance Characteristics of Ultrasound, Computed Tomography, Magnetic Resonance Imaging, and Postiron Emission Tomography for Hepatocellular Carcinoma Detection: Studies Comparing Imaging with Pathological Examination of Explanted Livers after Orthotopic Liver Transplantation or Partial Hepatectomy

Patients

Ultrasound

CT

MRI

with Study Rode

Patients

Population

HCC

Sensitivity

Specificity

Sensitivity

Specificity

Sensitivity

Specificity

43

Cirrhotics

13

46%

95%

54%

93%

77%

57%

25

Cirrhotics

9

89%

71%–

56%–

69%–

50%–

63%–

75%

67%

75%

56%

81%

(235)

Teefey (236)

Gamberin-

106

Cirrhotics

19

58%

94%

53%

94%

NA

NA

21

Cirrhotics

21

67%

100%

57%

100%

NA

NA

Gelwan (220)

Shapiro (237)

Kim (238)

Dodd

with HCC

52

Cirrhotics

18

38%

92%

NA

NA

NA

NA

200

Cirrhotics

34

50%

98%

NA

NA

NA

NA

200

Cirrhotics

14 a

NA

NA

68%

81%

NA

NA

430

Cirrhotics

59

NA

NA

NA

NA

35

Cirrhotics

9

NA

NA

89% b

88%

NA

NA

70

Cirrhotics

45

62% c

NA

82%

NA

89%

NA

27

30%

96%

NA

NA

NA

NA

(239)

Miller (240)

Peterson (241)

Taourel (242)

Yao (243)

with HCC

Bennett

&u&

200

Cirrhotics

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(244)

Llovet

55

Cirrhotics

29

NA

NA

47% d

NA

(245)

100% e

95%

for all lesions (84%) d

Takayasu

100

HCC

100 f

84%

NA

(246)

a

NA

NA

NA

Includes one cholagniocarcinoma.

b

CT with injection of iodized oil.

c

included 11 additional patients with incidental HCC >2 cm found on explant.

d

For lesions 11 to 20 mm

e

MRI with angiography.

f

84% (93%) b

Lesions Table of Conte nts > Vo lu me I > Se ction II - Gen eral Co nside ration s > Chapter 7 - Ph ysioanatomic Co nside ration s

Chapter 7 Physioanatomic Considerations Ian R. Wanless

Key Concepts z

The branching pattern of large vessels and ducts is used for defining the segmental nomenclature used by radiologists and surgeons.

z

Anomalies of the vessels and ducts are of importance to surgeons.

z

Bile ducts are supplied by arteries. Arterial injury may lead to ischemic strictures of the ducts, especially after transplantation.

z

The liver receives most of the splanchnic blood flow. After severe obstruction at any level of the hepatic vasculature, collateral channels become a source of bleeding and are partly responsible for hepatic encephalopathy.

z

The microvasculature of the liver consists of small branches of portal and hepatic veins that interdigitate in a regular pattern, allowing the definition of parenchymal subunits called acini or lobules.

z

Arterioles communicate with portal veins through the periportal end of the sinusoids. In cirrhosis, these communications dilate and, therefore, contribute to portal hypertension.

z

Hepatocytes are exposed to gradients of nutrients and waste products, leading to zonal metabolic specialization and zonal variation in the susceptibility to ischemia and drug toxicity.

z

The sinusoids are lined by fenestrated endothelial cells that lack basement membranes. This anatomy facilitates rapid exchange between plasma and hepatocytes.

z

Hepatic lymph is formed at the sinusoidal level when there is increased sinusoidal pressure, especially with outflow obstruction.

z

Sinusoidal macrophages (Kupffer cells) are important in host defense.

z

Perisinusoidal stellate cells store vitamin A and, when activated, produce collagen that contributes to the pathogenesis of cirrhosis.

z

There are two major anatomic forms of chronic liver disease: Cirrhosis and nodular regenerative hyperplasia.

z

Nodular regenerative hyperplasia occurs when multiple acini undergo ischemic atrophy and the less-affected acini undergo

This lymph may accumulate as ascites.

compensatory hyperplasia. z

Cirrhosis develops when the stromal habitat of hepatocytes is damaged and replaced by dense collagen. The topographic distribution of the resulting parenchymal extinction correlates exactly with the obliteration of small veins.

P.182 Anatomic knowledge is required for understanding the normal hepatic physiology and the pathogenesis of disease. This chapter presents a summary of normal anatomy, some physiologic correlates, and a description of the major anatomic abnormalities found in human liver disease. This chapter represents an evolution of the legacy provided by Dr. Aron Rappaport in the earlier editions of this book. Material of current general interest has been retained in this edition. Earlier editions may be consulted for citations of historical interest.

Surface Anatomy The liver is shaped like a wedge, with its base against the right abdominal wall and its tip pointing to the spleen. The normal liver extends from the fifth intercostal space in the midclavicular line down to the right costal margin. It measures 12 to 15 cm coronally and 15 to 20 cm transversely. The lower margin can usually be felt below the costal margin during inspiration. Transcutaneous puncture for liver biopsy is commonly located in the midaxillary line in the third interspace below the upper limit of liver dullness during full expiration, commonly in the ninth intercostal space. The median liver weight is 1,800 g in men and 1,400 g in women (1). The adult liver weight is between 1.8% and 3.1% of body weight in 80% of individuals (2,3). Liver weights in fetuses and children are relatively greater, being 5.6% at 5 months gestational age, 4% to 5% at birth, and 3% at 1 year of age (4,5).

▪ Figure 7.1 Posterior view of the liver. The marks impressed on the liver surface by neighboring organs mirror its topographic relations. (Drawn by M. Thompson.) (From Wanless IR. Anatomy and developmental anomalies of the liver. In: Feldman M, Scharschmidt BF, Sleisenger MH, eds. Sleisenger and Fordtran's gastrointestinal and liver disease, 6th ed. Philadelphia: WB

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Saunders, 1997:1056, with permission.)

Impressed by its molding against adjacent organs, William Osler quipped that the liver was present only for packing purposes. Therefore, the superior, anterior, and lateral surfaces are smooth and convex to fit against the dome of the diaphragm. The muscle bundles of the diaphragm often impress grooves in the superior surface. The costal margin often marks a transverse groove on the anterior surface (corset deformity). The posterior surface has indentations from the colon, kidney, and duodenum on the right and from the stomach on the left (Fig. 7.1). Deeper grooves, called fissures, are formed where extrahepatic vessels or cords press against the developing liver. Three of these structures, the umbilical portion of the left portal vein (PV), the ductus venosus (ligamentum venosum), and the umbilical vein (ligamentum teres), form the umbilical fissure. P.183 The liver is covered by the fibrous capsule of Glisson (or Walaeus). At the porta hepatis, the connective tissue of the capsule is continuous with the fibrous sheath, which invests the portal vessels and ducts and follows them to their smallest ramifications. The capsular peritoneum reflects onto the diaphragm and continues as the parietal peritoneum. The reflections form the coronary ligaments, the right and left triangular ligaments, and the falciform ligament (Fig. 7.1). These ligaments hold the liver firmly in its place and allow the passage of lymphatics, small vessels, and nerves. There is a large bare area where the liver is attached to the diaphragm and retroperitoneum. The vena cava, being retroperitoneal, lies on the bare area and is held to the liver by a ligament or bridge of the liver parenchyma between the caudate and right lobes. The falciform ligament connects the liver to the diaphragm and anterior abdominal wall. The lower free edge of the falciform ligament, called the round ligament, contains the obliterated umbilical vein. The falciform ligament ascends the anterior surface of the liver, joins the reflections of the peritoneum left of the vena cava, continues posteriorly as the lesser omentum in the fissure of the ductus venosus, and finishes at the hilum. Therefore, the falciform ligament, anteriorly, and the lesser omentum and umbilical fissure, posteriorly, divide the liver into the conventional right and left lobes. On the posterior surface, the transverse portal fissure contains the hilar vessels and demarcates the conventional right lobe anteriorly from the caudate lobe posteriorly (Fig. 7.1). The quadrate lobe is the portion of the right lobe anterior to the transverse fissure and is delimited on the right by the gallbladder and on the left by the umbilical fissure. The hepatoduodenal ligament connects the liver to the superior part of the duodenum. It is part of the lesser omentum, which sheathes the hepatic artery (HA), PV, nerves, bile duct, and lymph vessels, all being present within the porta hepatis. In the ligament the common bile duct lies to the right, the HA to the left, and the PV behind them. However, variations in the topography of the HA are common. There are several variations in the gross anatomy and topography of the liver (6,7). The relative size of the right and left conventional lobes is variable, being equal in size in 7% of individuals and greater on the left in 4% (7). Riedel's lobe is a caudal prolongation of the right lobe, which may give a false impression of hepatomegaly (Fig. 7.2). The falciform left lobe is an elongated lobe that extends laterally and posteriorly like a scythe, found in 19% of individuals (7). Extreme atrophy of the left lobe (4%) may be a result of vascular anomalies occurring early in life (8) or the extinction of parenchyma occurring after acquired vascular obstruction. The left lobe may be attached to the rest of the liver by a narrow pedicle. Accessory livers may be found in the ligaments or mesentery or on the surface of the gallbladder, spleen, or adrenals (6).

▪ Figure 7.2 Liver with Riedel's lobe, a prominent caudal extension of the right lobe.

Segmental Anatomy Division of the liver at the falciform ligament and umbilical fissure does not correspond to the division based on branch points in the vascular supply. Surgical imperative has led to the search for functional divisions within the liver. The anatomic studies of Rex and others (9,10,11,12) demonstrated that the liver can be divided on a different plane into right and left livers (or hemilivers), each with its own blood supply and duct drainage. The right hemiliver comprises 50% to 70% of the liver mass. The liver can be further divided into a total of eight segments on the basis of the vascular or bile duct distribution (7,12,13,14,15,16) (Figs. 7.3 and 7.4). The segmental nomenclature devised by Couinaud has received the widest acceptance. This classification was based on the divisions of the PVs. However, the branching of the PVs to the left lobe is irregular because of the entry of the umbilical vein, making it desirable to adopt a nomenclature based on the divisions of the arteries or ducts, as suggested by Strasberg (17). This can be done without modifying the segments defined by Couinaud and rationalizes the diverse nomenclature used in different parts of the world. The Strasberg nomenclature is summarized in Figures 7.3 and 7.4 and Table 7.1. Most hepatic resections can be achieved by division either on Cantlie's line (between the gallbladder P.184 P.185 and vena cava) or near the falciform ligament. Surgical dissection along the planes between segments is relatively bloodless. Because the segments do not have surface landmarks, small resections are usually performed without attempting to identify the segmental

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boundaries (16). The segments vary greatly in size and shape among individuals (18), so that each operation is empirical and may be based on ultrasonography (19,20)

▪ Figure 7.3 Schematic diagram of the planes of division in the liver. The liver can be visualized as being divided into two hemilivers by the midplane of the liver. The hemilivers are each subdivided into two sections by right and left intersectional planes. Three of the sections are further subdivided into two segments each by intersegmental planes on the basis of the divisions of the ducts and arteries. The left medial section does not have a regular duct and artery division and is therefore called one segment (IV). However, for surgical convenience, it is subdivided into posterior and anterior portions (segments IVa and IVb, respectively, not shown). The caudate lobe is a separate segment (I) that is not part of the four main sections. IVC, inferior vena cava. (Courtesy of Dr. Strasberg.) (From Strasberg SM. Terminology of liver anatomy and liver resections: coming to grips with hepatic Babel. J Am Coll Surg 1997;184:413–434, with permission.)

▪ Figure 7.4 Schematic demonstration of the vascular relations of the segments (drawn by M. Thompson). The segments are numbered using the nomenclature of Couinaud. The remaining elements of nomenclature are those of Strasberg. The midplane extends along Cantlie's line from the vena cava to the gallbladder. The middle hepatic vein runs in this plane. The right and left intersectional planes contain the right and left hepatic veins, respectively. Each section is supplied by one of the four major arteries and bile ducts. The portal pedicles and hepatic veins interdigitate, so they do not lie in the same planes except for the umbilical portion of the left portal vein and the umbilical vein (a medial branch of the left hepatic vein), both of which are found in the umbilical fissure (also known as left intersectional plane). The sections of Strasberg coincide exactly with the segments of Healey and Schroy. The two sections of the right hemiliver correspond to the two right sectors of Couinaud. The tertiary structures of Strasberg and of Couinaud are called segments; these coincide with the areas of Healey and Schroy, except that segment IV is divided into two areas by these authors. (Modified from Wanless IR. Anatomy and developmental anomalies of the liver. In: Feldman M, Scharschmidt BF, Sleisenger MH, eds. Sleisenger and Fordtran's gastrointestinal and liver disease, 6th ed. Philadelphia: WB Saunders, 1997:1056, with permission.)

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Embryology The liver arises from the hepatic diverticulum of the foregut during the fourth week of gestation (7,21) (Fig. 7.5). As the embryo develops, the blood supply to this region evolves in an elaborate manner to deliver nutrients from three different sources in sequence: Yolk sac, placenta, and gut (7,17). Hepatocyte precursors, the hepatoblasts, arise from endodermal cells at the advancing front of the diverticulum and invade the mesoderm of the caudal portion of the septum transversum. The vitelline veins traverse the region, bringing blood from the yolk sac and the digestive tube to the heart. As hepatoblasts invade the mesenchyme, they disrupt the vitelline veins, tapping their blood supply. This supply is from the vitelline veins, segments of which later become the PV The hepatic bud is subdivided into cords by new capillaries called sinusoids. The sinusoidal flow coalesces into three major hepatic veins. At the time the main hepatic veins are developing, the entire liver is composed of only two lobules, and there is no artery and no left or right bile duct. As the hepatic veins and PVs begin to branch, the branches interdigitate to remain equidistant from each other, and the parenchyma is subdivided into numerous lobules or acini. It has been suggested that the portal and hepatic vessels invade the most ischemic parenchyma that is located at the nodal point of Mall, the point most distant from both PVs and hepatic veins (22,23). The hepatoblast cords develop into anastomosing tubular structures with central bile canaliculi that P.186 P.187 eventually communicate with the bile ducts. Most hepatoblasts differentiate into hepatocytes, but those adjacent to the portal mesenchyme differentiate into a layer of duct progenitors called the ductal plate (24,25). The ductal plate becomes bilayered and gradually forms segments with lumina. These segments form ducts that migrate away from the limiting plate to a more central location in the portal tracts near the PV. Portions of the ductal plate resorb, leaving a complex anastomosing network of ducts that continues to simplify in the weeks after birth (26). The common bile duct, left and right hepatic ducts, and gallbladder develop in the stalk region of the hepatic diverticulum. These ducts are continuous with the ductal plate in the cranial end of the diverticulum. As bile ducts develop, they become highly vascularized by arterioles and capillaries of the periductal plexus.

Table 7.1. Nomenclature for Resections of Liver

Name of operation Portion of liver excised

Strasberg

Couinaud, Goldsmith, and Woodburne

Single segment

Segmentectomy (e.g., segmentectomy III)

—

Two adjacent segments

Bisegmentectomy (e.g., bisegmentectomy V,

—

VIII)

Multiple segments

Segmentectomy (e.g., segmentectomy IV, V,

—

VI)

One fourth of liver (e.g.,

Left lateral sectionectomy

left lateral section)

Left lobectomy (segments II and III), left lateral segmentectomy

One half of liver, right

Right hemihepatectomy (may or may not

Right hepatectomy (segments V, VI, VII, and

hemiliver

include segment I [e.g., right

VIII), right hepatic lobectomy

hemihepatectomy with segment I a ])

One half of liver, left

Left hemihepatectomy

hemiliver

Left hepatectomy (segments II, III, and IV), left hepatic lobectomy

Three fourths of liver,

Right trisectionectomy or right

Right lobectomy (segments IV, V, VI, VII, VIII,

right hemiliver, and left

hemihepatectomy with left medial

± I), extended right hepatic lobectomy, right

medial section

sectionectomy

trisegmentectomy (Starzl)

Three fourths of liver, left

Left trisectionectomy or left

Extended left hepatectomy, extended left

hemiliver, and right

hemihepatectomy with right anterior

lobectomy, left trisegmentectomy (Starzl)

anterior section

sectionectomy

a

This comment also applies to left hemihepatectomy and the trisectionectomies.

Modified from Strasberg SM. Terminology of liver anatomy and liver resections: coming to grips with hepatic babel. J Am Coll Surg 1997;184:413–434, with permission.

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▪ Figure 7.5 Drawing to show three stages in the development of the hepatic vasculature. A: In the embryo, there are three paired venous beds that drain the placenta (umbilical veins), yolk sac, and intestinal tract (omphalomesenteric or vitelline veins), and the remainder of the body (cardinal veins). These beds converge on the sinal horns before entering the heart. The left and right vitelline veins are joined by three anastomoses to form a ladder-like structure with the intestinal tract intertwined. The extrahepatic portal vein develops from these vessels after selective obliteration of portions of the ladder (B and C). B: The left vitelline vein receives a tap from the left umbilical vein. The intrahepatic segment of this tap becomes the umbilical portion of the left portal vein. The flow in this segment reverses after birth and supplies segments of the left hemiliver. As the liver develops, the venous drainage of the parenchyma becomes focused on two vessels, the future right and left hepatic veins, and later the middle vein (not shown), which usually drains into the left hepatic vein. The ductus venosus develops as a through-channel from the left portal vein to the common hepatic vein. The remainder of the portal vein blood perfuses the sinusoids before reaching the hepatic veins. C: The vasculature is simplified with the removal of several segments including the most caudal anastomosis between the vitelline veins, the rostral portions of the left vitelline and left umbilical veins, and the right umbilical vein. The right lobe grows faster than the left because the left lobe loses the supply from the left vitelline vein and the left umbilical vein blood is shunted through the ductus venosus. The left umbilical vein actually lies in the midline and later shifts to the right of midline.

The liver occupies most of the abdominal cavity in the third month of gestation, in part because of large masses of sinusoidal hematopoietic cells. Thereafter, the right lobe grows faster than the left lobe but slower than the rest of the body. The liver cell cords remain tubular until birth, when they begin to remodel into double-cell plates and finally into single-cell plates by 5 years of age. Hematopoietic cells are still found in the sinusoids at birth and largely disappear from the liver by 4 weeks of age. The hepatoblast is a bipotential progenitor cell that is positive for cytokeratin 19 (CK19) and HepPar1. During organogenesis, these cells differentiate into hepatocytes (CK19-negative and HepPar1-positive) and small bile ducts (CK19-positive and HepPar1-negative) (25,27). CK7 is expressed later and its level continues to increase in the weeks after birth. Severe injury to the adult liver causes a return to the pattern of expression seen in hepatoblasts. Therefore, regenerating epithelial cells in the liver have features of both ducts and hepatocytes (28).

Large Vessels of the Liver The liver receives blood through the PV and through the HA, a branch of the celiac axis. Because the PV drains the blood of an area supplied by the other branches of the celiac axis and by the superior and the inferior mesenteric arteries, the hepatic blood flow depends on the flow in these arteries (29).

Portal Veins The PV is an afferent nutrient vessel of the liver that carries blood from the entire capillary system of the digestive tract, spleen, pancreas, and gallbladder. It is constant in length, but the branches are variable (30,31) (Fig. 7.6). The PV is formed behind the neck of the pancreas by the confluence of the splenic and superior mesenteric veins. It also receives the superior pancreaticoduodenal vein, the left gastric (coronary) vein, and the cystic vein. Usually the upper 5 cm of the PV is devoid of major branches, allowing easy surgical dissection. The splenic vein commences with five to six branches that return the blood from the spleen and unite to form a single nontortuous vessel. In its course across the posterior abdominal wall, it grooves the upper part of the pancreas, from which it collects numerous short tributaries. It runs close to the hilum of the left kidney and terminates behind the neck of the pancreas, where it joins the superior mesenteric vein at a right angle. Because of its nearness to the vessels of the left kidney, the splenic vein can be anastomosed to the renal vein. Its tributaries are the short gastric veins, the pancreatic veins, the left gastroepiploic vein, and the inferior mesenteric vein. In the distal splenorenal shunt operation, the short gastric veins are used for collateral drainage of the gastroesophageal varices. The superior mesenteric vein carries blood from the small intestine, ascending colon, and transverse colon. The inferior mesenteric vein returns blood from the area drained by the superior and the inferior left colic and the superior rectal veins. An important tributary of the portal trunk is the coronary vein. It runs upward along the lesser curvature of the stomach, where it receives some esophageal veins. In patients with portal hypertension, these enlarge to form varices. The portal trunk runs in the hepatoduodenal ligament in a plane dorsal to the bile duct and the HA and divides into two lobar veins before entering the portal fissure. The right lobar vein, short and thick, receives the cystic vein. The left lobar vein, longer and smaller, is joined by the umbilical vein and the paraumbilical veins. It connects with the inferior vena cava by the venous ligament. The left lobar vein gives branches to the quadrate lobe and also to the caudate lobe before entering the parenchyma at the left end of the porta hepatis. A separate branch may arise near the bifurcation to supply the caudate lobe. This vein is easily injured during dissection. The paraumbilical veins arise from the umbilical portion of the left PV and travel in the round ligament, where they may become evident as umbilical varices in the presence of portal hypertension. The umbilical vein is easily recanalized in infants, allowing access for blood sampling and angiographic visualization of the portal system. In addition to the main PV and its branches, the liver receives other veins from the splanchnic circulation, the parabiliary venous system of Couinaud (32). This highly variable plexus includes several veins that arise from the pancreaticoduodenal or pyloric veins and drain into the PV or directly into the inferior surface P.188 of segment IV and less often into other segments. This plexus provides examples of the metabolic effects of proximity to insulin source. Veins arising from the pancreatic region would carry blood with high insulin levels and pyloric veins would carry low-insulin-level blood. Because insulin determines the propensity of the liver to store triglycerides, the anatomy of these veins could explain some examples of focal fatty liver and focal fatty sparing (33).

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▪ Figure 7.6 Measurements of the portal vein and its main branches, in centimeters. (From Gilfillan RS. Anatomic study of the portal vein and its main branches. Arch Surg 1950;61:449, with permission.)

Anomalies of the portal venous system are relatively rare. The anterior segment of the right liver is occasionally supplied by a branch of the proximal left PV (34). Preduodenal PV may be a result of the persistence of the most caudad anastomotic channel between the vitelline veins (Fig. 7.5). It may be associated with the duplication of the PV, annular pancreas, duodenal diaphragm, or intestinal malrotation, producing duodenal obstruction (35). Congenital absence of the PV is associated with portosystemic shunting because the superior mesenteric vein and the splenic vein drain directly to the vena cava or left renal vein, usually separately (36). This may be associated with hepatoblastoma or nodular hyperplasia of the liver (often simulating a neoplasm), cardiac anomalies, and biliary atresia. The ductus venosus rarely remains patent after infancy and is associated with hypoplasia of the intrahepatic PV branches, nodular hyperplasia of the liver, atrial septal defect, and hyperammonemia (37). Atresia of the PV may be a congenital malformation often associated with other vascular anomalies or a response to neonatal injury such as omphalitis or PV thrombosis (38). When PV thrombosis occurs in the neonatal period, the vein does not grow so that in adulthood it appears as a thin fibrous cord (hypoplasia or agenesis). A thrombosed PV may develop numerous irregular intraluminal channels in addition to a leash of collaterals in the porta, giving a radiologic appearance called cavernous transformation of the PV.

Hepatic Veins There are three main hepatic veins. The middle and left veins unite before entering the vena cava in 65% to 85% of individuals (7,39). In 18% of individuals, there are two right hepatic veins draining into the vena cava (20). In another 23%, there is a separate middle or inferior right hepatic vein draining segments V or VI, respectively. The veins have variable branching patterns. There are axial veins with four to six orders of dichotomous branching at acute angles, as well as numerous much smaller branches nearly at right angles (Fig. 7.7).

▪ Figure 7.7 A: Hepatic veins shown on postmortem angiogram. The major rami branch dichotomously and receive smaller branches nearly at right angles. B: Magnified portion of (A).

P.189 The caudate lobe and adjacent parenchyma are usually drained by one or two small veins directly into the vena cava caudal to the main hepatic veins. When thrombosis of the main hepatic veins occurs, the veins of the caudate lobe are often spared, allowing survival and compensatory hyperplasia of this lobe (40). Anastomoses between branches of the hepatic veins are uncommon in the normal liver (41) but may be more frequent in the presence of diseases with portal hypertension (42). Anastomoses of veins to other lobes become enlarged and may be mistaken for the original hepatic veins on Doppler interrogation. Partial recanalization occurs, often leaving webs in the hepatic veins or vena cava. These webs were formerly thought to be congenital, although most are now considered to be acquired (43,44).

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Hepatic Arteries The common HA is the second major branch of the celiac axis (45). It courses to the right along the upper border of the pancreas in the right gastropancreatic fold, which conducts the artery to the medial border of the hepatoduodenal part of the lesser omentum. It ascends in front of the PV in 91% of humans and to the left of and behind the bile duct in 64% of cases. It gives off the left and the right HAs to supply the corresponding hemilivers. The right and left HAs each divide into two arteries that supply the right anterior and posterior sections and the left medial and lateral sections, respectively. The middle HA arises from the left or right HA and supplies the quadrate lobe. The cystic artery arises from the right HA in the upper part of Calot's triangle (formed by the cystic duct, common hepatic duct, and inferior surface of liver). The cystic artery divides into a superficial branch that is distributed to the peritoneal surface of the gallbladder and a deep branch that supplies the attached wall of the gallbladder and adjacent liver. In 75% of cases, the artery is single, and in 25%, there are two arteries with separate origins for the deep and superficial branches. Anomalies of the HA are frequent, occurring in half of the individuals (46). Angiographic studies of the HA demonstrate that the course of the arterial branches in the hilum deviates markedly from that of the PV, and in some cases the arteries may even cross the segmental fissures (47). However, the more distal arterial branches follow the PVs closely, “climbing along them like a vine on a tree” (48). Anomalies of the HA have gained new importance because of the advent of transplantation, aggressive resections, and intra-arterial chemotherapy. The most important anomaly is a right HA arising from the superior mesenteric artery to supply the entire right liver (14%) (49). Because this vessel may appear in P.190 Calot's triangle, it is at risk during cholecystectomy. The left HA arises from the left gastric artery in 14% to 25% of cases (45,49,50). This vessel enters the liver at the left end of the hilum and may fail to be ligated during resections, leading to hemorrhage. Each of the aberrant arteries may be the only HA so that its injury can damage the liver severely. The PV and HA to segment IV may cross to the left of the umbilical fissure before turning medially and, therefore, may be injured during left lateral segmentectomy. Ducts or small vessels cross this fissure in 20% of cases (13). There are extensive communications between the ultimate and the penultimate branches of the right, the middle, and the left HAs in the umbilical fossa and in the region around the caudate lobe. The HA is provided with collateral flow through its anastomoses with arteries arising from the celiac axis and superior mesenteric artery. Anastomoses between the left and right HAs may occur. The main collaterals of the common HA are right and left gastrics; right and left gastroepiploics; gastroduodenal, supraduodenal, retroduodenal, superior and inferior pancreaticoduodenals; aberrant HAs; and inferior phrenic arteries (51). If ligation of an artery is necessary for the control of hemorrhage, ligation of the left or right artery is safe. Ligation of the HA proximal to potential collaterals such as the right gastric artery or gastroduodenal artery is better than ligation of the proper HA. After ligation of an HA, anastomotic channels enlarge and reestablish flow within a day (52).

Hepatic Collateral Circulation Portal hypertension leads to the development of intra- and extrahepatic venous collaterals (53,54) (Fig. 7.8). Extrahepatic collaterals are important, because when dilated to form varices, they are susceptible to rupture and massive bleeding. Varices in the submucosa of the gastrointestinal tract are most often a problem, especially in the esophagus and stomach but also in the rectum and duodenum and at ostomy sites. Dilated umbilical or paraumbilical veins are found in 11% of patients with cirrhosis (veins of Sappey) (55). They may cause a venous hum and caput medusa at the umbilicus (Cruveilhier-Baumgarten syndrome). Their presence implies high pressure in the left PV and, therefore, intrahepatic vascular obstruction. The direction of flow in lower abdominal wall collaterals is caudad if the inferior vena cava is obstructed, as in some patients with Budd-Chiari syndrome. Varices may be found at sites where the gastrointestinal tract or pancreas becomes retroperitoneal or adherent to the abdominal wall because of pathologic processes. These “veins of Retzius” establish connections between the portal bed and the ascending lumbar azygos, renal, and adrenal veins.

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▪ Figure 7.8 Diagram of portal circulation. The most important sites for the potential development of portosystemic collaterals are shown. A, Esophageal submucosal veins, supplied by the left gastric vein and draining into the superior vena cava through the azygous vein. B, Paraumbilical veins, supplied by the umbilical portion of the left portal vein and draining into abdominal wall veins near the umbilicus. These veins may form a caput medusa at the umbilicus. C, Rectal submucosal veins, supplied by the inferior mesenteric vein through the superior rectal vein and draining into the internal iliac veins through the middle rectal veins. D, Splenorenal shunts: Created spontaneously or surgically. E, Short gastric veins communicate with the esophageal plexus. (From Wanless IR. Anatomy and developmental anomalies of the liver. In: Feldman M, Scharschmidt BF, Sleisenger MH, eds. Sleisenger and Fordtran's gastrointestinal and liver disease, 6th ed. Philadelphia: WB Saunders, 1997:1057, with permission.)

Within cirrhotic parenchyma, shunts are formed by anastomoses between smaller branches of the portal and hepatic veins, as discussed later (56). These shunts allow blood to bypass the sinusoidal exchange surface, leading to functional impairment. This effect is made worse by the creation of large shunts. In addition, any procedure that decreases portal flow to the sinusoids increases the likelihood of thrombosis, further increasing intrahepatic resistance. Titration of these benefits and liabilities is an important feature of surgical management. Large spontaneous shunts may be beneficial in lowering portal pressure and should not be disturbed without due consideration. P.191 Portosystemic shunting appears to be responsible for reduced peripheral vascular resistance, possibly through the enhanced release of nitric oxide (57). Dilated vascular channels in the lungs lead to intrapulmonary shunting with hypoxemia and increased cardiac output.

Lymphatics Lymphatic channels are divided into deep and superficial networks (41,58). The former run parallel to the branches of the portal vessels and hepatic veins and the latter are found in the capsule. There are numerous anastomoses between these networks through small branches percolating through the capsule. The superficial lymphatics from the convexity form a dense network that coalesces into 14 groups of lymphatic trunks that drain through the coronary and falciform ligaments, through the diaphragm, and into esophageal and xiphosternal nodes. From the undersurface of the liver, they drain into hepatic hilar nodes. The deep lymphatics following the portal tracts reach the hepatic nodes at the left side of the porta hepatis, and the lymphatics along the hepatic veins drain to lymph nodes near the vena cava. The portal lymphatic trunks drain 80% of the hepatic lymph. The formation of lymph is discussed in the Section “Microanatomy.”

Nerves The liver has a rich sympathetic and parasympathetic innervation (59,60,61). Fibers derive from lower thoracic ganglia, the celiac plexus, the vagi, and the right phrenic nerve to form the plexi about the HA, PV, and bile duct. Most fibers are organized into the anterior and posterior trunks that enter the liver at the hilum. A few fibers enter at hepatic veins and ligaments. The arteries are innervated mainly by sympathetic fibers. The bile ducts are innervated by both sympathetic and parasympathetic fibers. Unmyelinated sympathetic fibers send branches to individual hepatocytes in zone 1. Nerve discharges are propagated from one hepatocyte to another through gap junctions (62). Most hepatic nerve fibers are aminergic or peptidergic, with a few cholinergic fibers. Intra-acinar cholinergic fibers do occur in the guinea pig. Immunohistochemical studies have demonstrated many other substances in some hepatic nerve fibers, including vasoactive intestinal peptide, neuropeptide Y, glucagon, somatostatin, neurotensin, and calcitonin gene–related peptide. The effects of nerve stimulation are partially mediated by prostaglandins synthesized in nonparenchymal cells of the liver. There may be local baroreceptors capable of detecting sinusoidal hypertension and leading to reflex renal artery vasoconstriction (63,64). Afferent nerves may be responsible for pain when the liver is distended. Stimulation of the nerve bundles around the HA and PV mainly results in a sympathetic discharge that alters the metabolism and hemodynamics of the liver. Glucose and lactate output are increased. Ketone and urea production, ammonia uptake, oxygen consumption, arterial and portal blood flow, and bile flow are reduced. Sympathetic nerve stimulation may exacerbate the effect of toxins (65). Parasympathetic stimulation is thought to increase glycogen synthesis and reduce glucose release. Hepatic parasympathetic activity has an important effect on skeletal muscle insulin resistance (66). Nerve action is modified by prevailing levels of hormones, especially insulin and glucagon. Resection of the anterior nervous plexus increases the concentration of bile salts and pigments in bile and impedes the accumulation of triglycerides in the liver. The clinical importance of this effect is uncertain. After transplantation, the denervated state of the liver persists (67), although hepatic blood flow and metabolic functions of the liver appear to be normal (68).

Biliary System The biliary system includes the bile canaliculi, intrahepatic and extrahepatic bile ducts, peribiliary glands, gallbladder, and ampulla of Vater (27). The intrahepatic ducts begin at the bifurcation of the common hepatic duct.

Large Ducts and Gallbladder The nomenclature of the large intrahepatic ducts will vary with the system used for naming the hepatic subunits (see preceding text). Each hepatic segment has a bile duct draining into a sectoral duct that drains into the right or left hepatic duct, which drains the right or left hemilivers, respectively. Caudate lobe drainage is variable, with ducts usually entering both right and left ducts. The junctions of the segmental, hepatic, and common hepatic ducts are also highly variable (69). The right and left hepatic ducts join to form the common hepatic duct at the right end of the portal fissure. The common hepatic duct is 1 to 5 cm long (mean 2 cm), is 0.4 to 1.3 cm in diameter (mean, 0.66), and is situated to the right of the HA and in front of the PV (70). It is joined by the cystic duct at its right side to form the common bile duct (ductus choledochus) that runs another 5 to 8 cm to the ampulla of Vater. The supraduodenal part of the common bile duct lies in the right border of the lesser omentum. The pancreatic part of the common bile duct passes retroperitoneally P.192 behind the first portion of the duodenum. It then runs in a groove on the posterior surface of the head of the pancreas, anterior to the inferior vena cava. At the left side of the duodenum, it is joined in 70% to 85% of cases by the pancreatic duct (of Wirsung) and forms a common channel of variable length (71). When a dilatation is present, it is called the ampulla of Vater (72). The common channel resides within an elevation of the duodenal mucosa called the major papilla (of Vater). The sphincter of Oddi consists of circular muscle fibers that surround the common bile duct in its course through the duodenal wall (73). Circular muscle fibers are also present around the end of the pancreatic duct and around the tip of papilla; longitudinal fibers are also present. The sphincter of Oddi is inhibited by cholecystokinin, assisting the expulsion of bile into the duodenum. An elongated common channel has been associated with congenital bile duct dilatation (74). Bile reflux may occur after papillotomy or surgical anastomoses with the intestine, resulting in recurrent cholangitis. The gallbladder is a receptacle that receives up to a liter of bile daily, concentrating it by sodium-coupled water transport and expelling it on stimulation by cholecystokinin. The gallbladder is a pear-shaped sac with a volume of 30 to 70 mL and measuring 3 cm in width and 7 to 10 cm in length. Its parts are designated as fundus, body, and neck. It lies on the undersurface of the right liver lobe, with the fundus projecting beyond the inferior border of the liver where the lateral margin of the rectus crosses the costal margin. The body is

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directed upward and to the left. Posteriorly, fundus and body are in close relation with transverse colon and duodenum, respectively. Gallstones can perforate into these viscera. The neck of the gallbladder is curved anteriorly and, when enlarged, forms the so-called Hartmann's pouch. The mucosa of the neck forms a spiral valve of Heister that continues into the cystic duct. The spiral valve has the function of regulating bile flow into and out of the gallbladder. The cystic duct measures 4 to 65 mm in length (mean, 30 mm) and 4 mm in average diameter (75). The arterial supply of the bile ducts comes mainly from many branches of the common HA, especially the retroduodenal artery and the right HA (45,76). The gallbladder may be supplied by one, two, or three arteries. The cystic artery usually arises from the right HA. The veins of the gallbladder are variable, draining into the liver at the gallbladder bed or into the veins from the common bile duct, but eventually draining into branches of left and/or right PV (7). The lymph vessels of the gallbladder, hepatic ducts, and upper parts of the common bile duct empty into the lymph nodes of the hilum. Those of the lower common bile duct drain into nodes near the head of the pancreas. Nerve fibers supplying the extrahepatic ducts and gallbladder derive mainly from the sympathetic hepatic plexus laced around the HA. These fibers also receive filaments from the right and left vagus nerves. Some nerve fibers deriving from the plexus can be seen running along the common bile duct. Sparse ganglion cells are present in the muscularis and the mucosa of the gallbladder. Their nervous connection with the spinal system is brought about by fibers from the right phrenic and musculophrenic nerves. Because these nerves derive from the third or fourth cervical nerve, the anatomic basis for shoulder pain in gallbladder disease is evident. Vagal stimulation causes gallbladder contraction (77). Histology of the bile ducts and gallbladder has been reviewed by Frierson (78) and Nakanuma et al. (27). The wall of the extrahepatic ducts is formed by fibrous tissue with elastic fibers; smooth muscle is scanty or absent (79), except at the lower end of the common duct where muscle rings are conspicuous. The gallbladder wall contains abundant smooth muscle and little fibrous tissue. Rokitansky-Aschoff sinuses are outpouchings of the gallbladder mucosa through defects of the muscularis and are found in almost all gallbladders having calculi. The ducts of Luschka are small ducts in the areolar tissues of the hepatic surface of the gallbladder that communicate with intrahepatic bile ducts, but not usually with the gallbladder cavity, and may leak hepatic bile after cholecystectomy. The mucosa has numerous papillary folds in the gallbladder, distal pancreatic duct, distal common bile duct, and ampulla. The mucosa of bile ducts and gallbladder consist of a single layer of columnar epithelium and a lamina propria. A few goblet cells are present, especially in the ampulla. Somatostatin-containing cells may be present in the ampulla, a possible source for the development of somatostatinomas arising at this site. Mucous-secreting accessory glands (peribiliary glands) are in the lamina propria of the gallbladder neck and extrahepatic bile ducts and adjacent to the large intrahepatic ducts (80).

Intrahepatic Ducts The intrahepatic ducts have been defined as ductules (0.4 mm) (27). These measurements are approximate because the definition is also dependent on the relation to the segmental boundaries and on histologic pattern. The large and septal bile ducts have a well-demarcated dense fibrous wall and high columnar epithelium with basal nuclei and small mucin droplets. These ducts express the blood group antigens. Interlobular ducts are located near the center of portal tracts and have minimal or no fibrous investment, and P.193 the epithelium is low columnar or cuboidal and lacks mucin. There is a periodic acid-Schiff–positive basement membrane. The ductules are located near the limiting plate and have cuboidal epithelial cells. The presence of a few ductules may be considered normal, but large numbers are a feature of cholestatic or regenerating liver. Throughout the biliary tree, each duct is usually accompanied by an artery of similar diameter, a helpful guide when evaluating the absence of ducts. The peribiliary glands accompanying intrahepatic large and septal ducts may be located within the walls (intramural) or form clusters outside the fibrous wall (extramural). Intramural glands are mucin rich, and extramural glands may be mucinous or serous, rarely with focal pancreatic acinar differentiation. Peribiliary glands are hypertrophied in patients with Clonorchis infestation and may be the tissue source of some cholangiocarcinomas (81). These glands may form retention cysts at the hilum in case of cirrhosis, PV obstruction, and polycystic kidney disease (82), rarely causing obstructive jaundice (83). Intrahepatic bile ducts are the site of injury in many diseases, resulting in duct destruction, secondary cholestasis, and eventually, cirrhosis in severe cases. In primary biliary cirrhosis, ducts up to 0.3 mm in diameter are destroyed by an immune process. In primary sclerosing cholangitis, the most severely involved ducts are extrahepatic and large intrahepatic ducts, with less severe duct destruction in the smaller branches. Ducts less than 0.1 mm in diameter are the focus in chronic allograft rejection, graft versus host disease, Alagille's syndrome, and reactions to a variety of drugs and toxins. Neonatal biliary atresia, polycystic liver disease, and several other syndromes may be a result of a variety of insults to the developing ducts at the ductal plate stage (84). The peribiliary vascular plexus is hypertrophied in livers with cirrhosis or with PV obstruction and is especially prominent in congenital hepatic fibrosis, where it may fill on portal venogram and appear to form a duplication of the portal tree (85).

Variations and Surgical Implications A portion of the right liver may drain into the left duct system in 6% of cases (7). In 25% of cases, a branch of the right duct drains into the left duct (86). The common hepatic duct may receive accessory hepatic ducts. If the common hepatic duct is absent, the right and left hepatic ducts may run separately and join close to the duodenum; the right duct receives the cystic duct. Other variations include a main duct draining into the gallbladder, the cystic duct draining into the right hepatic duct, and the right hepatic duct draining into the cystic duct (7,69,85,87). The cystic duct usually enters the bile duct at an angle but may run parallel or curve behind the duct in a spiral manner. The relations of the large ducts and vessels near the hilum are variable, but the peripheral branches of these structures run together within portal tracts. Because ducts depend on arterial supply, ischemic necrosis, with or without stricture, may occur in the large bile ducts after transplantation, especially if the HA is compromised. Duct strictures, rupture, and infarction of the gallbladder have also been found after hepatic arterial injection of alcohol or chemotherapeutic agents, possibly because of injury to the peribiliary vascular plexus (27). Numerous conditions are characterized by congenital or acquired anomalies of the duct system. Aberrant biliary ducts, the vasa aberrantia, form anastomoses between the gallbladder and small ducts in the adjacent liver. These ducts are liable to leak bile after cholecystectomy. Accessory mucous-secreting periductal glands are located all along the duct system. These may develop retention cysts that, rarely, encroach on the duct lumen to produce obstructive jaundice (83). Congenital dilatation of the intrahepatic and/or extrahepatic ducts, known as choledochal cyst, is a rare cause of cholangitis or obstructive jaundice, usually presenting in childhood (see Chapter 43). Caroli's disease is a subset of this condition, with dominant dilatation of the intrahepatic ducts. Congenital fibrocystic disease occurs in a variety of anatomic patterns, often with coexistent renal disease. Clusters of dilated ducts within portal tracts, von Meyenburg complexes, are markers of adult polycystic kidney and polycystic liver diseases (88). Biliary atresia, the absence or obliteration of the extrahepatic bile ducts, is one of the most common causes of cirrhosis in childhood. Anomalies and diseases of the gallbladder have been reviewed by Weedon (89). Absent gallbladder and double gallbladder are rare (0.05% and 0.02%, respectively) (90). Agenesis is associated with other congenital defects of the intestines or bones. Bilobed,

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hourglass-constricted gallbladder and that with folded fundus (phrygian cap) or persistent septum favor retention and inflammation. Diverticulum also occurs. The gallbladder can be completely buried in liver substance or attached loosely to it by a mesentery (floating gallbladder).

Microanatomy Normal Human Histology When viewed histologically, the normal liver displays a uniform arrangement of portal tracts separated by parenchyma composed of hepatocellular plates and P.194 sinusoids. Terminal hepatic venules are located equidistant from portal tracts, which contain arteries, ducts, nerves, and PVs in a connective tissue stroma (Fig. 7.9). The stroma within portal tracts normally contains a small number of macrophages, plasma cells, and lymphocytes.

▪ Figure 7.9 Normal portal tract from human liver, showing several small ducts, two arteries, a portal vein, and occasional lymphocytes (hematoxylin and eosin).

Although often called portal triads, the number of each of these elements varies with the size of the tract. In a study of needle biopsies, the number of profiles per portal tract was 2.3 ducts, 2.6 arteries, and 0.7 veins (91). The average minimum diameters were 13 µm for ducts, 12 µm for arteries, and 35 µm for PVs. In healthy infants, the number of ducts per portal tract is less than that in adults. The average number of portal tracts was 19 per biopsy, with a mean biopsy length of 1.8 cm. The interpretation of liver biopsies requires an assessment of sampling error. Biopsies obtained by the transjugular route are half this size, and in fibrotic conditions, the number of portal tracts available is often less than half a dozen.

Hepatocytes Hepatocytes comprise 65% of the cells in the liver and 80% of hepatic volume. Hepatocytes are polyhedral with a central spherical nucleus. They are arranged in plates, one cell in thickness, with blood-filled sinusoids on each side of the plates (Fig. 7.10) (92). The cytoplasmic membrane has specialized domains providing a canalicular region on the lateral walls and numerous microvilli on the sinusoidal (basolateral) surfaces. The canalicular domains of adjacent hepatocytes are bound together by tight junctions to form bile canaliculi that coalesce and ultimately drain into ducts within portal tracts. Hepatocytes are also attached by gap junctions that have a role in the transmission of nerve impulses from zone 1 to zone 3. Normal and abnormal ultrastructure of hepatocytes has been reviewed elsewhere (90,93).

Endothelial Cells and Sinusoids The length of a human sinusoid varies from 223 to 477 µm. The diameter of the sinusoids can vary from 6 to 30 µm and can increase to 180 µm when necessary. Zone 1 sinusoids are smaller than those in zone 3 (94). The caliber depends on active contraction of endothelial cells and stellate cells, as well as passive distension (95). Leukocytes are large compared to sinusoidal diameter, so that blood flow compresses the sinusoidal wall, promoting exchange between plasma, subendothelial fluid, and hepatocytes (94). The sinusoidal surface is covered with a layer of endothelial cells that enclose the extravascular space of Disse (Fig. 7.10). Hepatic sinusoids differ from systemic capillaries in that the endothelial cells are fenestrated, subendothelial basement membrane material is scanty, Weibel-Palade bodies are absent in most species, and intercellular junctions are absent, permitting the passage of large macromolecules including lipoproteins but not chylomicrons (92,96). Fenestrations are grouped into clusters called sieve plates. Mean fenestration diameter in the rat is 150 to 175 nm, occupying 6% to 8% of the endothelial surface area (96). The fenestrations can change in size in response to various stimuli, including pressure, neural impulses, endotoxin, alcohol, serotonin, and nicotine (97). They are large in zone 1 and smaller and more numerous in zone 3. Agents that disrupt actin filaments can almost double the number of fenestrations within minutes (97). The permeability of fenestrations has been studied with marker particles. In the rat, liposomes 400 nm in diameter are readily engulfed by hepatocytes. The ability to traverse fenestrations may depend on the deformability or surface charge of the particles (98). Sinusoidal endothelial cells also differ from continuous endothelial cells in their immunohistochemical phenotypes. Factor VIII–related antigen, Ulex europaeus agglutinin I binding, platelet/endothelial cell adhesion molecule-1 (PECAM-1), CD34, and 1F10 are features of continuous endothelial cells but not of sinusoidal endothelial cells (99). Sinu soidal endothelial cells express low-affinity Fc γ-receptors (CD32, FcR), lipopolysaccharide-binding protein complex receptors (CD14), thrombospondin receptors (CD36), class II histocompatibility receptors (CD4), and intercellular adhesion molecule-1 (100,101). During embryogenesis, the transition from P.195 P.196 continuous to fenestrated phenotype occurs between 5 and 20 weeks' gestation (100). The fenestrated phenotype partially reverts to the continuous endothelial phenotype in chronic hepatitis, cirrhosis, and hepatocellular carcinoma (101), including the expression of CD34,

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PECAM-1, and laminin receptors α6 β1 and α2 β1 (99).

▪ Figure 7.10 Ultrastructure of sinusoids. (Courtesy of Dr. Bioulac-Sage.) A: Sinusoid showing endothelium covering the subendothelial space of Disse (star). This space contains stellate cell processes (*) and hepatocellular microvilli. Note that the microvilli extend into recesses between hepatocytes. The endothelial cells are fenestrated (arrows) (transmission electron microscopy [TEM] ×4,840). B: Closer view shows endothelial fenestrations and microvilli of a hepatocyte (TEM ×10,000). C: Endothelial fenestrations are clustered into sieve plates (scanning electron microscopy [SEM] ×29,400). (From Bioulac-Sage P, Saric J, Balabaud C. Microscopic anatomy of the intrahepatic circulatory system. In: Okuda K, Benhamou J-P, eds. Portal hypertension: Clinical and physiological aspects. Tokyo: Springer-Verlag, 1991:17, with permission.) D: Hepatocellular plates are one cell in width, with bile canaliculi (arrow) visible on the fractured edges of the plates. Hepatocytes (H), sinusoids (S), and Kupffer cells (K) are seen. Collagen fibers have been pulled from the spaces of Disse (SEM ×2,000). E: The space of Disse (star) contains several stellate cell processes (*) and collagen bundles (C). Endothelial fenestrations are labeled (arrows). H, hepatocyte nucleus (TEM ×6,000). F: Sinusoid with a Kupffer cell in the lumen and a stellate cell containing lipid (*) in the space of Disse (TEM × 2,000).

During the development of cirrhosis, the sinusoids also acquire some morphologic features of systemic capillaries; the space of Disse becomes widened with collagen, basement membrane material is deposited, endothelial fenestrations become smaller and less numerous, and hepatocellular microvilli are effaced. These changes, often called capillarization of sinusoids (102), likely reduce transport across the sinusoidal walls and explain some of the hepatocellular dysfunction seen in cirrhosis. Nitric oxide produced by hepatocytes, Kupffer cells, and sinusoidal and arterial endothelial cells may cause increased sinusoidal blood flow, thereby protecting the liver during various injuries (103,104,105). Increased blood flow may be beneficial by preventing the adhesion of leukocytes and platelets that might otherwise injure the endothelium (60). Nitric oxide production may have a role in the hepatopulmonary syndrome (106) and hepatorenal syndrome (107). Endothelin-1 is produced by activated stellate cells and causes these cells to contract (108). Circulating endothelin-1 may have a role in hepatorenal syndrome (107). Endothelial cell injury is important in endotoxemia, hypotensive shock, and cold perfusion of donor livers (109,110). Donor livers may develop rounding-up and detachment of endothelial cells that may be responsible for some instances of primary nonfunction after transplantation (111). It has been suggested that thickening of the space of Disse may contribute to poor transport of materials to the hepatocellular surface (112), as well as possibly contributing to portal hypertension (113). Amyloid fibril deposition may widen the space of Disse dramatically and cause severe atrophy of subjacent hepatocytes. With severe amyloidosis, hepatomegaly, cholestasis, and noncirrhotic portal hypertension have been reported (114). Cellular infiltration within the lumina of sinusoids occurs in Gaucher's disease, mastocytosis, leukemias, and myeloproliferative disorders, but such infiltration does not correlate with the clinical evidence of portal hypertension (115). Obstruction of small veins is more likely to cause portal hypertension in these diseases because sinusoids are distensible and have the ability to regenerate (38).

Formation of Lymph Most of the hepatic lymph derives from the subendothelial space of Disse, and a minority, perhaps 10%, is formed by leakage from capillaries of the peribiliary plexus. The smallest recognizable lymph capillaries are found in the interstitial tissue in terminal portal tracts and adjacent to terminal hepatic venules (116) (Fig. 7.11). The pathways that connect these lymph capillaries to the space of Disse have been difficult to demonstrate, and it is believed that lymph percolates through the collagen and proteoglycan matrix of the interstitium. Collagen bundles in the space of Disse appear to be continuous with fibers in the portal tracts, marking a submicroscopic channel for lymph flow. Lymph could also flow in the matrix investing the portal inlet venules and arterioles that penetrate the limiting plate.

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▪ Figure 7.11 Mall's drawing of portal and periportal tissue showing the space of Disse (perivascular lymph space, PVL), the space of Mall (perilobular lymph space, PLL), and lymph vessel (l) after injection with gelatin. The space of Disse is continuous with the space of Mall. In living beings, the space of Mall may be virtual where lymph percolates among interstitial matrix fibers. Also shown are lobule (L), sinusoids (C), connective tissue fibers (W), bile duct (B), and artery (A). (From Mall, FP. On the origin of the lymphatics in the liver. Bull Johns Hopkins Hosp 1901;12:146, with permission.)

Lymphatics have endothelial cells with no basement membrane and no pericytes. PVs can be distinguished from lymphatic channels by the presence of smooth muscle cells surrounding the former (117). The larger lymphatic vessels and trunks have valves. Because of the large endothelial fenestrations in sinusoidal (and presumably lymphatic) endothelial cells, there is little or no oncotic pressure gradient between the plasma and the subendothelial tissue fluid, and the protein content of hepatic lymph is approximately 80% that of plasma. With a very low oncotic pressure gradient, the main stimulus for the formation of lymph is sinusoidal pressure. A 1mm rise in efferent pressure doubles the hepatic lymph flow. The liver normally produces 1 to 3 L/day but this may increase to 11 L/day in cirrhosis or extrahepatic outflow obstruction (118). Communication between small bile ducts P.197 and lymphatics may allow for the increased formation of lymph seen after biliary tract obstruction (119).

Biliary Tree The biliary tree begins with a network of bile canaliculi that empty into bile ducts (Fig. 7.12). Canaliculi have contractile and secretory properties. Canaliculi in isolated hepatocyte doublets have been shown to undergo rhythmic contraction thought to represent peristaltic activity in the intact liver (120). These contractile functions are provided by a pericanalicular band of microfilaments composed of actin, myosin II, tropomyosin and α-actinin, and associated proteins, stabilized by a sheath of noncontractile intermediate filaments (121). The cholangiocytes lining small ducts transport water and solutes under hormonal control (122,123). Peribiliary glands also participate in the concentration of bile. Chloride transport is dependent on the cystic fibrosis transmembrane conductance regulator, explaining the decreased water content of bile, hepatolithiasis, and secondary biliary cirrhosis seen in some patients with cystic fibrosis.

▪ Figure 7.12 Bile canaliculi. A: Scanning electron micrograph of methacrylate injection cast of rat biliary tree (×860). B, terminal twig of the bile duct; b, canal of Hering; c, bile canaliculi emptying into canals of Hering. (From Murakami T, Itoshima T, Hitomi K, et al. A monomeric methyl and hydroxypropyl methacrylate injection medium and its utility in casting blood capillaries and liver bile canaliculi for scanning electron microscopy. Arch Histol Jpn 1984;47:223, with permission.) B: Photomicrograph of human liver with slight cholestasis, stained for carcinoembryonic antigen (CEA). CEA is present in the distribution of the bile canaliculi that could not be seen on hematoxylin and eosin.

The small bile ducts are supplied by arteries (124) (Fig. 7.13). Terminal branches of the HA supply a general capillary plexus within the

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portal tract and a peribiliary vascular plexus and also empty directly into zone 1 sinusoids (125). The general and peribiliary vascular plexi eventually drain into sinusoids through capillary connections known as the internal roots of the PV. The peribiliary vascular plexus has been divided into inner, intermediate, and outer layers. The inner layer has fenestrated endothelium, suggesting a role in water exchange. Similar fenestrated endothelium is found in the gallbladder mucosa.

Stellate Cells The stellate cells (fat-storing cells or Ito cells) are located within the spaces of Disse. Their cytoplasmic droplets normally contain abundant vitamin A, mostly P.198 as retinyl palmitate (126). These cells can be identified by the presence of immunoreactivity for smooth muscle actin, transient autofluorescence, and histochemical affinity for gold and silver. When activated by various cytokines, stellate cells are transformed into myofibroblast-like cells that have reduced vitamin A storage, increased content of myofilaments and α-smooth muscle actin, and increased expression of procollagen gene transcripts. Stellate cells, in their activated state, are the principal hepatic fibroblasts (127,128). Evidence that many forms of hepatic injury activate hepatic macrophages and that these cells release cytokines capable of activating stellate cells has been presented (129). Stellate cells can also secrete matrix metalloproteinases that degrade matrix proteins (130). Activated stellate cells contract under stimulation by sympathetic discharge or endothelin-1 secretion (95,108,131). By this mechanism, stellate cells could exacerbate portal hypertension.

▪ Figure 7.13 Scanning electron micrograph of cast blood vessels in the liver of rhesus monkey. Peribiliary arterial plexus (B) receives blood from arterial branches (A) by means of afferent arterioles (a). The plexus supplies sinusoids (S) through efferent arterioles (e). Note the grooves indicating arteriolar sphincters (Sph). Arterioles (a 1 ) bypass the plexus and empty directly into sinusoids. P, portal vein (methyl methacrylate cast ×135). (Courtesy of Dr. T. Murakami, Department of Anatomy, Okayama University, Japan.)

Kupffer Cells Kupffer cells are the resident macrophages in the liver. They comprise more than 80% of tissue macrophages in the body and 15% of cells in the liver. Although capable of proliferation in situ, they are also recruited from the peripheral blood (127). Kupffer cells reside in the sinusoids, with pseudopodia anchored to endothelial cells or, occasionally, hepatocytes. They may form part of the sinusoidal wall.

Liver-Associated Lymphocytes A few lymphocytes are normally found in portal tracts and sinusoids even after washout with saline. Portal lymphocytes are 90% T cells with CD4/CD8 ratio of 1.6, whereas sinusoidal lymphocytes are 60% T cells with a CD4/CD8 ratio of 0.4 and 30% natural killer cells (CD56+). Sinusoidal lymphocytes reside in the lumen adherent to Kupffer cells and endothelial cells (127). Many sinusoidal lymphocytes are large, with cytoplasmic granules, and are also called pit cells because of the resemblance of the granules to grape seeds (128). Pit cells are most numerous in zone 1 sinusoids. These cells are thought to have a role in killing tumor cells and virus-infected cells. The granules of pit cells contain perforin, a protein that injures cell membranes. Pit cell tumoricidal activity is enhanced by the presence of Kupffer cells (128).

Stroma Connective tissue stroma supports the capsule, the portal tracts from hilum to periphery, and the sinusoidal walls. The composition of the stroma varies with location. Connective tissue of the capsule and portal tracts is mostly type I and III collagen and elastin. Reticulin fibers, defined by their histochemical affinity for silver, are largely composed of type III collagen and fibronectin (132). They are located in the spaces of Disse, where they give tensile strength to the parenchyma. Type IV collagen forms a basal lamina around small vessels. Many noncollagenous glycoproteins are present in the matrix, including laminin, fibronectin, tenascin, entactin, vitronectin, undulin, osteonectin, and Von Willebrand's factor (133). Laminin links basement membrane collagen to the integrins attached to endothelial cells and epithelial cells. The function of tenascin is uncertain, but it is mitogenic for a variety of cell types. Vitronectin stimulates fibroblast migration; von Willebrand's factor is found within endothelial Weibel-Palade bodies and in basement membranes (133). Proteoglycans bind to cells and matrix proteins and have roles in matrix–cell and cell–cell interaction. In scarred livers, there is an absolute increase in many matrix proteins. The bulk of the scar tissue is type I collagen. After

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hepatocellular necrosis, the connective tissue framework is rapidly repopulated with hepatocytes in an orderly manner. If regeneration is delayed, the deposition of collagen by stellate cells destroys the framework and prevents restitution to normal. The stromal collagen is important in the prevention of tears in the blood vessels and sinusoidal walls. Focal dissolution of reticulin leads to parenchymal hemorrhage and blood-filled cysts (peliosis hepatis) (134,135). Mineral oil deposits are present in portal tracts and adjacent to hepatic venules in more than half of human livers and are usually accompanied by a slight mononuclear infiltrate (136).

Three-Dimensional Organization of the Liver The organization of the hepatic parenchyma has been conceptualized in two contrasting models: The acinus and the lobule (137,138,139). Terminal PVs interdigitate with the terminal hepatic venules, with sinusoids bridging the gaps between these vessels. The terminal hepatic venules can be considered as being in the center of a lobule or the periphery of several acini. The acinar approach is discussed in detail here. The simple liver acinus is a small parenchymal mass, irregular in size and shape, arranged around an axis consisting of a terminal hepatic arteriole, portal venule, bile ductule, lymph vessels, and nerves that grow out together from a small portal field (Fig. 7.14). The simple liver acinus lies between two (or more) terminal hepatic venules with which its vascular and biliary axis interdigitates. In a twodimensional view, it occupies sectors of two adjacent hexagonal or pentagonal fields. The plates and cords of the simple acini are in continuity with adjacent acini in three dimensions; there P.199 is no capsule separating the acini from one another. It can be assumed that the dividing line between the acini is the watershed of biliary drainage, so that each acinus empties its biliary secretion into the axial bile ductule.

▪ Figure 7.14 Liver acinus in humans. The acinus occupies sectors only of two adjacent hexagonal fields and reaches their central veins (CV). The terminal portal branch (TPV) is injected with India ink and runs perpendicular to the two terminal hepatic venules (THV) with which it interdigitates (thick cleared section ×300).

A complex acinus is a clump of tissue composed of at least three simple acini whose axial channels branch in three dimensions from the preterminal stalk (Fig. 7.15). Each of its terminal branches forms the axis of a simple acinus. A sleeve of tissue composed of tiny clumps (acinuli) surrounds the preterminal channels. These acinuli are nourished by axial venules and arterioles branching off the preterminal vessels. Structural and functional unity in a complex acinus can be demonstrated by injecting colored materials (140). The P.200 axial vessels of the simple acini are always the same color as the parent vessels of the complex acinus. Three or four complex acini form larger clumps of tissue, the acinar agglomerates. Acini or acinuli also form a sleeve of parenchyma around the axial stem servicing the agglomerate.

▪ Figure 7.15 Complex acinus in humans. The sinusoids injected with India ink are supplied by three terminal portal branches and their parent preterminal vessel (pret). These portal venules help form the axial channels of a complex acinus cut longitudinally. The sleeve of parenchyma around pret is formed by acinuli (a 1 , a 2 ); axpv, axial portal venule supplying the sinusoids of a 1 . The poorly injected white areas (in the upper corners) are parts of zone 3 around terminal hepatic venules, which are not shown (150 µm-thick section ×88).

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▪ Figure 7.16 Group of acinar agglomerates in a human liver injected with India ink. Three large portal branches grow out in different directions from a portal space (PS). One of these runs diagonally through the field and represents the axis of an acinar agglomerate. From this portal branch, preterminal (1) and terminal (2) branches grow out and form the axes of complex and simple acini, respectively (100 µm-thick cleared section ×18).

The acinar agglomerate has unity because the main route of vascular supply and the biliary drainage are common to the whole clump, as well as to its subdivisions. The hierarchy can be continued because several agglomerates are supplied by a single macroscopic portal tract. The PVs supplying agglomerates in the human liver are approximately 150 µm in diameter (140) (Fig. 7.16). All branches of the hepatic vein interdigitate with HA and PV branches of similar order; this creates a hexagonal or pentagonal pattern when seen histologically in cross-section (Figs. 7.17 and 7.18). The acinus is an ideal physiologic unit for understanding many vascular and biliary events in human biology (see discussion on cirrhosis in subsequent text). The conceptual advantage of the acinus is that the blood supply to a portion of the parenchyma and the bile duct draining the same parenchyma reside in the same portal triad. “Thus, structural, circulatory, and functional unity is established in this small clump of parenchyma” (141) (Fig. 7.19). By contrast, the classical hexagonal lobule is supplied by several separate PV branches, arteries, and ducts, each of which also supplies other adjacent lobules (140). McCuskey (142) notes that all the essential relationships are present within smaller units called hepatic microvascular subunits. This concept is validated by the existence of focal degenerative changes that involve portions of parenchyma that are subacinar in size. The smallest useful unit is that in which there is a significant barrier to blood flow between adjacent units. Recent studies show that PV blood is distributed by numerous small inlet venules, giving a portal supply that is more diffuse and less granular than that pictured by the original description of the acinus (137,138,139). These analyses suggest that isobars of oxygen tension are sickle shaped (Fig. 7.20), with the parenchymal subunits being components of a hedge rather than individual grapes on a vine. Although parenchymal subunits are difficult to visualize in the normal human liver, they become evident in pathologic conditions such as nodular regenerative hyperplasia, in which there is a pruning of the portal venous supply. As with a hedge, when individual portal units are pruned, the remaining units undergo hyperplasia to form an P.201 array of spherical units, revealing the underlying acinar structure. The hierarchical arrangement of simple, complex, and agglomerate acini can be appreciated in livers with prominent atrophy or necrosis (141). In this century-long debate, it is useful to note that parenchymal subunits do not exist in the human liver. The debate concerns the best way to imagine their structure if they did exist.

▪ Figure 7.17 Interdigitation of portal and hepatic vein branches. Human liver injected with India ink. Two horizontal terminal portal branches (2, 3), forming the axes of acini, interdigitate with three vertical terminal hepatic venules (4, 5, 6), around which they arch (cleared thick section × 110).

Hepatocellular Heterogeneity The liver is anatomically situated to receive high concentrations of nutrients and certain hormones from the intestines and pancreas. Gradients of these substances, as well as oxygen and waste products, are found across the functional units of the liver. These gradients are not constant but vary with cycles of feeding and exercise. The position of hepatocytes within the acinus is reflected by the specialized functions of these hepatocytes (138,143,144,145) (Fig. 7.21). Zone 1 hepatocytes are adapted to high oxidative activities, having numerous large mitochondria. Dominant processes in zone 1 are gluconeogenesis, β-oxidation of fatty acids, amino acid catabolism and ureagenesis, cholesterol synthesis, and bile acid secretion. Zone 3 is an ideal location for exergonic processes, including glycolysis and lipogenesis. There is a narrow rim of hepatocytes adjacent to terminal hepatic venules that remove ammonia from the blood by synthesizing glutamine. Zone 3 is also the site of general detoxification and biotransformation of drugs. Metabolic zonation is accompanied by gradients of some anatomic features (141). Mitochondria are larger and more numerous and lysosomes and Golgi are more abundant in zone 1. Smooth endoplasmic reticulum is more abundant and nuclear volumes are larger in

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zone 3. Endothelial fenestrae are larger and less numerous in zone 1. Kupffer cells, large granular lymphocytes, stellate cells, and sympathetic nerve endings are all more numerous in zone 1. There are also gradients in the composition of matrix proteins (146). The control of metabolic zonation has been found to operate at the pretranslational level, with a few exceptions. Therefore the gradients of the enzyme protein and the enzyme messenger ribonucleic acid tend to parallel each other. Enzyme expression usually varies during the feeding cycle or changes in oxygen tension, and the zonation is said to be dynamic. It is likely that many signals interact to produce dynamic zonation. Glucose and oxygen gradients each have an effect on various enzymes, and these gradients are interdependent (147,148). The sensors of oxygen gradients may be mediated by heme-containing proteins. Stable zonation that does not vary with metabolic signals is a result of intercellular or cell–matrix interactions. For example, glutamine synthetase activity P.202 may depend on close approximation of hepatocytes with some element of the venules, although this is controversial (144,149). Metabolic zonation is lost in cirrhosis (150). Glutamine synthetase expression was undetectable in one study (150).

▪ Figure 7.18 Vascular and biliary architecture of an acinar agglomerate and the relation of the acini to the adjacent hexagonal lobule. Note the arcuate courses of the terminal portal branches, the irregularly arranged simple acini, and the short portal vessels that form the axes of tiny acinuli constituting the mantle of parenchyma around the longitudinally cut portal space. Intercommunicating paths of acini and acinuli are indicated by arrows. PS I, PS II, PS III, portal spaces; LA, LA 1 , simple liver acinus; LA 2 , simple acinus penetrating a hexagonal field situated well above the level of origin of the acinus; THV, terminal hepatic venule; D, channels of Deysach; 1, 2, 3, circulatory zones of the simple liver acinus.

Although hepatocellular heterogeneity is largely determined by the zonal gradients of environment cues, some heterogeneity occurs because of local genetic aberration. This can be seen in hemochromatosis as iron-free foci within livers that are otherwise diffusely pigmented (151). These represent dysplastic foci with increased risk for the development of hepatocellular carcinoma (152). Clusters of hepatocytes with excess cytoplasmic glycogen occur in patients with various disorders of ureagenesis and in leprechaunism, presumably because of focal genetic variation (153).

Clinical Importance of Hepatocellular Heterogeneity Metabolic heterogeneity is responsible for zonal injuries that are of diagnostic value to the pathologist. The distribution of necrosis and steatosis in response to chemical injury is often zonal (154). Sharply defined zone 3 necrosis is characteristic of toxicity due to acetaminophen, Amanita phalloides, pyrrolizidine alkaloids, and various hydrocarbons such as halothane and carbon tetrachloride. Zone 1 necrosis has been found with allyl alcohol, phosphorus, and high-dose iron ingestion. Zone 2 toxicity is rare in humans but has been produced in animals with ngaione, furosemide, and beryllium. Cocaine toxicity in rodents may affect different zones depending on preexisting enzyme induction (155).

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▪ Figure 7.19 Blood supply of the simple liver acinus and the zonal arrangement of cells. The acinus occupies adjacent sectors of neighboring hexagonal fields. Zones 1, 2, and 3, respectively, represent areas supplied with blood of first, second, and third quality, with regard to substrate, oxygen, and nutrients. These zones center on the terminal afferent vascular branches, terminal bile ductules, lymph vessels, and nerves and extend into the triangular portal field from which these branches crop out. Zones 1′, 2′, and 3′ designate corresponding areas in a portion of an adjacent acinar unit. In zones 1 and 1′, portal inlet venules empty into sinusoids. Note that zone 3 approaches the preterminal portal tract, nearly reaching the inner circle (A). PS, portal space; THV, terminal hepatic venules (central veins).

Systemic hypoperfusion generally produces zone 3 necrosis. This pattern may be altered by local factors. For example, in disseminated intravascular coagulation, zone 1 sinusoidal fibrin deposition results in maximum ischemia being located in zone 1 or 2. Zone 2 necrosis has been reported in some patients with hypotensive shock (156). Viral hepatitis usually produces spotty necrosis in all zones but often with an ill-defined zone 3 predominance. Yellow fever often produces zone 2 necrosis. Herpesvirus produces well-demarcated necrosis that does not follow a zonal distribution. In hemochromatosis, hemosiderin is deposited predominantly in zone 1 hepatocytes. This is useful to P.203 distinguish hemosiderin from lipofuscin, the latter occurring predominantly in zone 3 hepatocytes. Proximity to a source of insulin favors the development of steatosis, as seen after the instillation of insulin in the peritoneal cavity during dialysis and in the case of decreased steatosis in infarcts of Zahn, where PV supply to the tissue is obstructed.

▪ Figure 7.20 The acinar structure of the hepatic microcirculation, as conceived by Rappaport (140) and modified by Matsumoto and Kawakami (137). In both models, the margins of the shaded zones represent planes of equal blood pressure (isobars), oxygen content, or other characteristic. The models differ in the shape of the isobars surrounding terminal portal venules. The acinus is bulb-shaped, and the classical hexagonal lobule is comprised of several wedge-shaped portions (called primary lobules, indicated by dotted lines, upper left), which have cylindrical (sickle-shaped) isobars. The nodal region is the nodal point of Mall (22). (From Wanless IR. Anatomy and developmental anomalies of the liver. In: Feldman M, Scharschmidt BF, Sleisenger MH, eds. Sleisenger and Fordtran's gastrointestinal and liver disease, 6th ed. Philadelphia: WB Saunders, 1997:1059, with permission.)

Control of Hepatic Microcirculation The terminal PVs supply sinusoids directly, giving a constant but sluggish blood flow (140,141). In contrast, arterioles drain into terminal portal venules and zone 1 sinusoids, giving a pulsatile but small volume flow that appears to enhance sinusoidal flow, especially in periods of reactive arterial flow, as in the postprandial state. Groups of sinusoids shift their work asynchronously. The change from the storage phase of inactive sinusoids to flow activity demonstrates, at the microscopic level, the function of the liver as a “venesector and blood giver of the circulatory system” (157). Arterial flow varies inversely with PV flow. The mechanism of this hepatic arterial buffer response is based on the washout of locally produced adenosine (158). When portal venous flow is reduced, adenosine accumulates and causes dilatation of the arterial resistance vessels; the reverse also occurs. The relative contribution of arterial and portal venous flow varies between regions of the liver and with

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gravity and other physiologic variables (159). Conductance of PVs increases with distention, causing portal pressure to be little altered by large changes in PV flow (160). In addition to arteriolar tone, local control of the microcirculation may depend on the contraction state of sinusoidal endothelial and stellate cells (95). Regional blood flow is of practical importance when investigating focal lesions such as focal nodular hyperplasia and neoplasms. The venous and arterial circulation can be differentially imaged by using computed tomography with arterial portography (CTAP) or CT scan with intravenous contrast injection. Hepatocellular carcinoma, hepatic adenomas, metastases, and focal nodular hyperplasia are mostly supplied by arteries and are therefore hypodense with CTAP (161,162). Cirrhotic nodules, dysplastic nodules, and small hepatocellular carcinomas may have a portal venous supply and are usually isodense on CTAP.

▪ Figure 7.21 Schematic diagram of various metabolic processes that show zonal differences across the acinus. PV, portal vein; ThV, terminal hepatic venule; D, bile duct; A, hepatic arteriole; NAD, nicotinamide adenine dinucleotide; NADP, nicotinamide adenine dinucleotide phosphate; UDP, uridine diphosphate; ER, endoplasmic reticulum; Z 1 , periportal area; Z 3 , periacinar and perivenular area. (The latter is derived from portions of zone 3 of several adjacent acini.) (Modified from Rappaport AM, Wanless IR. Physioanatomic considerations. In: Schiff L, Schiff ER, eds. Diseases of the liver, 7th ed. Philadelphia: JB Lippincott, 1993:1–41, Jungermann K, Kietzmann T. Zonation of parenchymal and nonparenchymal metabolism in liver. Annu Rev Nutr 1996;16:179–203.) (For description see text; for references see both the sources.)

P.204

Physioanatomic Aspects of Human Liver Disease Regeneration of Hepatocytes The normal liver maintains a constant mass that is determined by the needs of the host. If a partial hepatectomy is performed, the organ grows to regain much of the original mass in 10 days in rodents and in a few weeks or months in humans (163). If a liver is transplanted into a new host, the new liver grows (by mitosis) or shrinks (by apoptosis) to the size of liver expected for the host's body size. Hepatocyte dysfunction, such as chronic cholestasis in primary biliary cirrhosis or primary sclerosing cholangitis, appears to be a signal to initiate cell proliferation because the liver may be twice the normal weight in the early stages of these diseases. There is controversy about the source of the hepatocytes participating in regeneration. The normal resting liver has a very low mitotic rate. After many types of injury, mitoses become readily visible in hepatocytes from all acinar zones. However, some labeling studies suggested that mitosis is particularly active in the periportal region, giving rise to the hypothesis that hepatocytes are born in zone 1 and migrate in their lifetimes to zone 3 (164). This “streaming liver” concept implies the presence of stem cells, now considered to be located in the smallest radicles of the biliary tree, the canals of Hering (165,166). Cells in this location are thought to be able to differentiate into cholangiocytes and hepatocytes (167,168). It appears that the bulk of cell replacement, in acute and subacute injury models, is by panacinar mitosis. The stem cell and streaming liver mechanisms may be important in severe injury states (169). The stem cell population may be replenished by cells migrating from the bone marrow (170,171,172,173,174). P.205 In a healthy human liver, half the hepatocytes are diploid and the other half are polyploid (175). One third of the hepatocytes are binuclear. The processes of polyploidization and binucleation are irreversible, so that polyploidy increases with age. These processes may protect long-lived hepatocytes against mutation. During a regenerative stimulus, binucleation and polyploidy decrease as binucleating growth is suppressed. Therefore, after regeneration, freshly divided cells have small and uniform nuclei, in contrast to the polyploid resting cells. Putative signals for the initiation of the cell cycle in hepatocytes include hepatocyte growth factor (HGF), produced in all the major types of nonparenchymal liver cells; epithelial growth factor, produced in the salivary glands and hepatocytes; transforming growth factor-α (TGF-α), produced in the hepatocytes, and tumor necrosis factor (TNF) (see Chapter 2) (176). Endotoxin stimulates TNF secretion, and TNF stimulates Kupffer cells to secrete interleukin-6, which is an important mediator of hepatocellular regeneration. HGF and TGF-β are bound to the extracellular matrix (177). Insulin and glucagon support hepatocyte growth in culture and in vivo, although they are not complete mitogens for hepatocytes. Although the details of this complex system are not fully understood, it is clear that cytokines and growth factors derived from multiple cells types are involved. Therefore, gut-derived endotoxin, pancreatic hormones, activated Kupffer cells, and sinusoidal blood flow will influence hepatocellular regeneration (171).

Table 7.2. Clinical and Anatomic Features of the Major Forms of Chronic Liver Disease

Anatomic

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Portal

Hepatocellular

Parenchymal

Fibrous

Extrahepatic

Obliteration

Obliteration

or large

of small

of small

intrahepatic

hepatic

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diagnosis Cirrhosis,

hypertension

dysfunction

extinction

++

++

+++

micronodular

Cirrhosis,

portal veins

PV block

veins

+++

±

+++

++

±

++

+

±

+++

+

-

+

+

+

+

+

++

-

++

±

±

Many, broad

+

±

++

macronodular

Cirrhosis,

septa

Many, narrow

++

+

+++

venocentric a

Between hepatic veins, portal tracts not involved

Cirrhosis,

±

±

+

Moderate,

incomplete

narrow, or

septal

incomplete

Cirrhosis,

+

±

+

Moderate,

incomplete

narrow, or

septal with

incomplete

large portal vein obstruction

Extrahepatic

++

±

-

None

±

±

-

None or

portal vein obstruction b

Nodular regenerative

rare

hyperplasia

Gradings are for typical examples but gradings can vary within each anatomic category. a Typically b Examples

seen with Budd-Chiari syndrome. are Portal vein thrombosis, portal vein agenesis, cavernous transformation of the portal vein.

Pathogenesis of Chronic Liver Disease Chronic liver disease is usually defined as hepatic injury lasting for at least 6 months. The end stage of chronic liver disease has often been divided in two clinicopathologic forms: Cirrhosis and noncirrhotic portal hypertension, the former being associated with portal hypertension and hepatic dysfunction and the latter with portal hypertension and nearly normal function. Recent anatomic studies have demonstrated that these two categories can be further subdivided (Table 7.2) (38). All types of chronic liver disease are associated with vascular obstruction, and the various anatomic patterns can be explained by the distribution and severity of the obstructive lesions. Each anatomic pattern is the summation of numerous local parenchymal lesions of either atrophy or extinction. Therefore, understanding the pathogenesis of atrophy and extinction is necessary to understand the pathogenesis of each anatomic pattern.

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▪ Figure 7.22 The histogenesis of cirrhosis. There are two basic types of cirrhosis, venocentric and venoportal. The type of cirrhosis is determined by the distribution of vascular obstruction, as illustrated by these examples with Budd-Chiari syndrome. A, B: Venocentric cirrhosis occurs when parenchyma near the obstructed hepatic veins (HV) shows contiguous cell loss and fibrosis (extinction) and cirrhotic nodules (dark tissue) contain portal tracts with patent veins. The periportal tissue survives because of retrograde portal vein drainage. C, D: When hepatic vein obstruction is followed by portal vein thrombosis, retrograde portal vein (PV) flow is not possible and the periportal tissue cannot support hepatocytes. This is shown in (C) where portal tracts (black) are usually accompanied by periportal tissue (gray) except in regions affected by PV thrombosis (arrows). In (D) the arrow indicates a portal tract with obstructed PV and absent periportal tissue. E: Venoportal cirrhosis occurs when portal tracts are incorporated into the septa located adjacent to the cirrhotic nodules. Arrow shows obliterated portal vein (B, D, and E: Elastic-trichrome stain). (Modified from Tanaka M, Wanless IR. Pathology of the liver in Budd-Chiari syndrome: Portal vein thrombosis and the histogenesis of venocentric cirrhosis, venoportal cirrhosis, and large regenerative nodules. Hepatology 1998;27:488–496, with permission.)

▪ Figure 7.23 Diagrammatic depiction of tissue remodeling in chronic hepatitis (A–F) and in alcoholic liver disease (G–L) during the development and regression of cirrhosis. Normal acini are shown in (A) and (G), with the sequence of events leading to small regions of parenchymal extinction in the following panels. Obstructed veins are shown as black circles. B: Obliteration of small portal and hepatic veins occurs early in the development of cirrhosis in response to local inflammatory damage. The supplied parenchyma becomes ischemic. C, D: Ischemic parenchyma shrinks and is replaced by fibrosis (process of extinction). The shrinkage is accompanied by close approximation of adjacent vascular structures. E: Septa are deformed and stretched by expansion of regenerating hepatocytes. F: As septa are resorbed, they become delicate and perforated before disappearing. Trapped portal structures and hepatic veins are released from the septa and are recognizable as deformed and ectopic remnants. Note the absence of portal veins. In alcoholic disease G–L, the sequence of events may differ from other forms of chronic liver disease. H: Sinusoidal fibrosis is often prominent before parenchymal collapse, leading to a pericellular pattern of fibrosis. I, J: Inflammation and fibrosis lead to hepatic and portal vein obliteration, with secondary condensation of preformed sinusoidal collagen fibers into a septum. K, L: After prolonged periods of inactivity, sinusoidal fibrosis and septa are resorbed. (Modified from Wanless IR, Nakashima E,

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Sherman M. Regression of human cirrhosis. Morphologic features and the genesis of incomplete septal cirrhosis. Arch Pathol Lab Med 2000;124:1599–1607, with permission.)

P.206 P.207 The two-hit vascular model allows one to predict the local parenchymal response to vascular obstruction (178,179). Normal liver parenchyma is supplied by arteries and PVs and is drained by hepatic veins. The dual blood supply, therefore, allows for two levels of ischemia. Mild ischemia may occur when any one of these vessels is obstructed, resulting in atrophy. Severe ischemia occurs when any two of these vessels are obstructed, leading to extinction. The evolution of extinction lesions is illustrated in Figure 7.22. The histologic appearance of the liver varies with time after injury, with progressive enlargement (nodular hyperplasia) of well-supplied regions of parenchyma, arterial dilatation and growth, and progressive resorption of collagen (178,180). These secondary events complete the genesis of the various patterns of chronic liver disease. Therefore, nodular hyperplasia occurring in the presence of atrophy produces the pattern of nodular regenerative hyperplasia. Nodular hyperplasia occurring in the presence of abundant extinction is the pattern called cirrhosis. The pattern of cirrhosis is further modified by the relative involvement of portal and hepatic veins (Fig. 7.23). Resorption of collagen in cirrhotic livers leads to macronodular cirrhosis, incomplete septal cirrhosis, and eventually almost a total regression of cirrhosis (Fig. 7.24). Significant regression presupposes that the activity of disease and the development of new obstructive events are minimized by spontaneous remission or effective therapy. The mechanism of vascular obstruction in chronic liver disease depends on the nature of the primary disease. In most forms of chronic hepatitis, portal and hepatic vein phlebitis occurs as a bystander effect of inflammation in adjacent tissue (181). In Budd-Chiari syndrome and chronic congestive failure, thrombosis is the cause of the vascular obliteration (179). In chronic P.208 biliary disease, bile salt injury is likely responsible for the hepatic vein obliteration, and portal inflammation may explain the PV obliteration. In established cirrhosis of any etiology, stasis commonly leads to secondary thrombosis or congestive venopathy of portal and hepatic veins and secondary parenchymal extinction that may be independent of the activity of the original disease (182,183). The significance of these thrombotic and congestive venopathy mechanisms is that they point to mechanisms that might be ameliorated by therapy. Antithrombotic therapy is often recommended in patients with obvious thrombotic disease such as Budd-Chiari syndrome and portal thrombosis (184) but may also be beneficial in other types of progressive liver disease. Congestive venopathy might be ameliorated by β-blockers or porta-caval or transhepatic shunt procedures.

▪ Figure 7.24 The time course of the histologic features of cirrhosis in relation to periods of activity. After cessation of activity, various histologic features regress at different rates. The balance of histologic features varies with the duration of low-activity disease, for example, between time points A and B. At time B, cirrhosis cannot be diagnosed histologically, although portal hypertension may remain. (Reprinted with permission, from Wanless IR. Regression of human cirrhosis. In Reply. Arch Pathol Lab Med 2000;124:1592–1593.)

The development of extinction in chronic hepatitis may be recognized as bridging necrosis in very active cases. In less active disease, there are clusters of apoptotic and atrophic hepatocytes, often with congestion of the sinusoids. As lesions are fully organized, they are identified by the approximation of hepatic veins to portal tracts after the intervening parenchyma has been resorbed. The formation of intrahepatic shunts in cirrhosis can be understood from this model. Arterioles from terminal portal tracts normally feed into zone 1 sinusoids. When the local terminal hepatic venule is obliterated, arterial flow seeks a patent channel with lower pressure. If the local PV is patent, it receives the arterial flow by retrograde flow in the zone 1 sinusoids (179). If the local PV is also obstructed, the arterial flow will drain laterally into those sinusoids that connect with a patent hepatic vein, likely the parent of the obstructed terminal hepatic venule. These favored sinusoids dilate and become part of an artery-to-hepatic vein shunt. If the nearest patent hepatic vein is too distant, the parenchyma becomes congested and eventually extinct.

Annotated References Arias IM, Boyer JL, Fausto N, et al. eds. The liver: Biology and pathobiology, 4th ed. New York: Raven Press, 2001. An admirable summary of hepatic physiology with abundant anatomic details. Couinaud C. Surgical anatomy of the liver revisited. Paris: Couinaud, 1989. An indispensible guide to embryology, anatomy, and surgical implication. MacSween RNM, Desmet VJ, Roskams T, et al. Developmental anatomy and normal structure. In: MacSween RNM, Burt AD, Portmann BC, et al. eds. Pathology of the liver, 4th ed. Edinburgh: Churchill Livingstone, 2002:1–66. A detailed review, strong in embryology, physiology, and ultrastructure (new edition expected in 2006).

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McCuskey RS. The hepatic microvascular system. In: Arias IM, Boyer JL, Fausto N, et al. eds. The liver: Biology and pathobiology, 3rd ed. New York: Raven Press, 1994:1089–1106. A detailed summary of the physiology of the microcirculation. Nakanuma Y, Hoso M, Sanzen T, et al. Microstructure and development of the normal and pathologic biliary tract in humans, including blood supply. Microsc Res Tech 1997;38:552–570. A detailed summary of the anatomy of the biliary tree. Okuda K, eds. Portal hypertension: Clinical and physiological aspects. Tokyo: Springer-Verlag, 1991. Several chapters appear on gross and microscopic anatomy, collaterals, and diseases with portal hypertension. Phillips MJ. The liver. An atlas and text of ultrastructural pathology. New York: Raven Press, 1987. The definitive volume on normal and pathologic ultrastructure.

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Editors: Schiff, Eugene R.; Sorrell, Michael F.; Maddrey, Willis C. Title: Schiff's Diseases of the Liver, 10th Edition Copyright ©2007 Lippincott Williams & Wilkins > Table of Contents > Volume I > Section II - General Considerations > Chapter 8 - Bilirubin Metabolism and Jaundice

Chapter 8 Bilirubin Metabolism and Jaundice Allan W. Wolkoff Paul D. Berk

Key Concepts z

Bilirubin is the final degradation product of heme, which is the prosthetic group of numerous important hemoproteins involved in oxygen transport (e.g., hemoglobin) or metabolism (e.g., P-450 cytochromes). The conversion of heme to bilirubin involves two enzymatic steps: Opening of the heme ring by heme oxygenase to form biliverdin, with the release of both carbon monoxide (CO) and iron, and reduction of biliverdin to bilirubin by biliverdin reductase.

z

Healthy adults produce a mean of 4 mg of bilirubin/kg body weight per day. Degradation in the reticuloendothelial system of the hemoglobin of dying erythrocytes generates 80% to 85% of daily bilirubin production. The remainder has multiple sources, including ineffective erythropoiesis in the bone marrow and the turnover of short-lived, nonhemoglobin hemoproteins including the various P-450 cytochromes. Because synthesis and degradation of these cytochromes occurs throughout the body, both heme biosynthesis and the heme oxygenase/biliverdin reductase pathway are widely distributed.

z

Bilirubin was long considered simply a biologic waste product. However, biliverdin and bilirubin have antioxidant properties, CO is important in cell signaling, iron plays a key role in the generation of reactive oxygen species, and both heme biosynthesis and heme degradation are tightly regulated. These observations suggest that, hemoglobin degradation aside, heme synthesis and degradation throughout the body may play a role in cellular antioxidant defenses.

z

Bilirubin formed in the periphery is kept in solution during transit to the liver by very tight binding to albumin. Once in the liver, it is transported from plasma to bile by four distinct steps: Hepatocellular uptake; binding to specific intracellular proteins; conversion to a water-soluble form by conjugation to glucuronic acids by the uridine-5′-diphosphate glucuronosyltransferase isoform UGT1A1; and the adenosine triphosphate (ATP)-dependent, carrier-mediated transport of the resultant bilirubin monoglucuronide (BMG) and bilirubin diglucuronide (BDG) across the canalicular domain of the plasma membrane into the bile canaliculus.

z

Jaundice is the yellow–orange discoloration of the skin, conjunctivae, and mucous membranes that results from an elevated concentration of bilirubin in plasma. Hyperbilirubinemias are usually classified into those that are predominantly unconjugated and those that are mainly conjugated. The latter often, in fact, involve elevations of levels of both the conjugated and unconjugated bilirubin fractions. Instances of hyperbilirubinemia in which other common hepatic biochemical test results are normal often reflect familial hyperbilirubinemias; the combination of hyperbilirubinemia with abnormalities of other hepatic biochemical tests suggests an acquired condition. Exceptions to this rule are not rare.

z

The plasma unconjugated bilirubin concentration reflects a balance between bilirubin turnover and hepatic bilirubin clearance (C B R ). Unconjugated hyperbilirubinemia can result from increased bilirubin turnover (e.g., hemolysis), decreased bilirubin clearance (e.g., neonatal hepatic immaturity, familial unconjugated hyperbilirubinemias), or situations in which both processes are occurring (neonatal immaturity in infants with glucose-6-phosphate dehydrogenase deficiency).

z

Reduced levels of UGT1A1 on either a congenital (Gilbert's and Crigler-Najjar syndromes) or an acquired basis (administration of certain human immunodeficiency virus protease inhibitors) and shunting of blood around the hepatic parenchyma in cirrhosis are the most frequent causes of a reduction in C B R . Hereditary (Dubin-Johnson syndrome) or acquired (hepatocyte injury) deficiencies of the canalicular transport system, or obstruction to the flow of bile down the biliary tract, are the principal causes of conjugated hyperbilirubinemia.

z

Application of molecular technology has led to extensive progress in understanding the pathogenesis of the familial hyperbilirubinemias. Gilbert's syndrome and Crigler-Najjar syndrome types I and II were long considered separate diseases, with separate patterns of inheritance. It is now recognized that they all reflect autosomal recessive disorders characterized by mutations of different severity in the gene encoding UGT1A1. Similarly, Dubin-Johnson syndrome is now known to reflect an inherited abnormality in multidrug resistance– associated protein 2 (MRP2), encoding an ATP-dependent canalicular plasma membrane transporter for bilirubin conjugates and a number of other non–bile acid organic anions. Of the five familial hyperbilirubinemias, only Rotor's syndrome remains unexplained in terms of molecular pathogenesis.

P.214 Bilirubin, a reddish-yellow heme degradation product, is produced principally by the breakdown of the hemoglobin of senescent red blood cells and eliminated from the circulation by the liver. Jaundice, derived from the French jaune (yellow), is the yellow–orange discoloration of the skin, conjunctivae, and mucous membranes, which is a consequence of an elevated concentration of bilirubin in plasma. Although mild hyperbilirubinemia may be clinically undetectable, jaundice becomes apparent at plasma bilirubin concentrations of 3 to 4 mg/dL. The threshold for its recognition depends on the patient's normal pigmentation, the lighting conditions under which the observation is made, and the particular fraction of plasma bilirubin whose concentration is elevated. Optimal interpretation of an elevated plasma bilirubin concentration is based on an appreciation of its metabolism, and in particular, its sources and disposition. These are the subjects of this chapter. Studies of bilirubin chemistry, metabolism, and genetic disorders underwent explosive growth in the 1960s through the 1990s, creating the foundation on which current work in the field is based. Because space limitations restrict the number of references that can be cited in this chapter, readers are frequently referred to review articles for detailed bibliographies of older work in this field (1,2,3,4,5,6,7,8,9,10).

Sources, Structure, and Plasma Transport of Bilirubin Bilirubin Production from Heme Bilirubin is the final, common end product of the metabolism of heme, the moiety found in hemoglobin, myoglobin, and other hemoproteins (Fig. 8.1). The formation of bilirubin is the result of a multistep, enzymatic process in which the porphyrin ring of heme is first opened at the α-bridge carbon in a stereoselective, enzymatic oxidative process carried out by the microsomal enzyme heme oxygenase. This step leads to the release of an iron atom and the formation of equimolar quantities of biliverdin, a green tetrapyrrolic pigment, and carbon monoxide (CO) (3,4,11,12,13,14,15). Biliverdin is a water-soluble pigment readily excreted unaltered by the liver. It is the principal bile pigment in many P.215 amphibia, fish, and birds. However, it does not readily cross the placenta. Accordingly, most mammals rapidly and quantitatively convert biliverdin to the reddish yellow pigment bilirubin through a reaction that is catalyzed by the enzyme biliverdin reductase (2,3,8,9,16). Heme oxygenase is present in macrophages throughout the reticuloendothelial system, including Kupffer cells of the liver, and certain epithelial cells, including hepatocytes and renal tubular cells (17). Biliverdin reductase is widely distributed in many cells throughout the body, including macrophages (16). The major sites of bilirubin production are the spleen and other compartments of the reticuloendothelial system, which degrade the hemoglobin of senescent and injured red blood cells. However, the degradation of heme to bilirubin can occur in many sites, including macrophages that migrate into hematomas containing extravasated hemoglobin. Because both heme oxygenase and biliverdin reductase are present in macrophages, the sequential steps in the conversion of heme to bilirubin are readily visualized at the edges of any bruise, where the purplish to green to yellow color changes reflect the conversion of extravasated and deoxygenated hemoglobin first to biliverdin and then to

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bilirubin (18,19).

▪ Figure 8.1 Pathway for the degradation of heme to bilirubin. Stereospecific opening of the heme macrocycle at the α-bridge carbon by the microsomal enzyme heme oxygenase results in the formation of equimolar amount of biliverdin and carbon monoxide. Biliverdin is subsequently reduced to bilirubin by the enzyme biliverdin reductase. MET, microsomal electron transport system; NADP, nicotinamide adenine dinucleotide phosphate; NADPH, nicotinamide adenine dinucleotide phosphate (reduced form). (Reproduced from reference Berk PD, Jones EA, Howe RB. Disorders of bilirubin metabolism. In: Bondy PK, Rosenberg LE, eds. Metabolic control and disease, 8th ed. Philadelphia: WB Saunders, 1979:1009–1088, with the permission of the publisher.)

Possible Cytoprotective Effects of the Heme Oxygenase/Biliverdin Reductase Pathway Although both heme oxygenase and biliverdin reductase were initially considered to function solely as a heme-degradative and waste disposal pathway, the P.216 widespread distribution of these enzymes in cells outside the reticuloendothelial system, the tight control of heme oxygenase activity achieved through the presence of both an inducible (HO-1) and a constitutive (HO-2) form of the enzyme, and the important biologic effects of the several products of heme degradation have led to a growing interest in this pathway (20). In this regard, both biliverdin and bilirubin have proved to be potent antioxidants, CO functions as both a signaling molecule and an important vasoactive regulator, and the iron released during heme degradation contributes to various forms of cellular cytotoxicity by facilitating the formation of reactive oxygen species (ROS). These findings suggest that cells may have evolved a fine control over the heme oxygenase/biliverdin reductase pathway specifically to regulate CO production for signaling and heme consumption and generation of bilirubin and biliverdin for their roles in counteracting intracellular oxidative and nitrosative stress (20,21). The existence of a specific oxidation/reduction cycle in which lipophilic ROS oxidize bilirubin to biliverdin, which is then re-reduced by biliverdin reductase, has been postulated (22) and debated (23). Such a cycle, analogous to the glutathione/glutathione disulfide (GSH/GSSG) cycle for detoxifying soluble oxidants, would permit bilirubin to destroy a 10,000-fold excess oxidants (22).

▪ Figure 8.2 Relative specific activities of hemoglobin protoporphyrin, fecal urobilin (stercobilin), and hippuric acid after administration of labeled glycine. The early labeled peak of stercobilin is derived from ineffective erythropoiesis and the turnover of heme enzymes; the late peak reflects the death of senescent erythrocytes. The observed specific activity of hemoglobin protoporphyrin is less than that predicted from the continued availability of labeled glycine for hemoglobin synthesis, as determined from the hippuric acid curve. This suggests some random loss of labeled erythrocytes, which may be the source of fraction II of labeled stercobilin. (Reproduced from reference Berk PD, Jones EA, Howe RB. Disorders of bilirubin metabolism. In: Bondy PK, Rosenberg LE, eds. Metabolic control and disease, 8th ed. Philadelphia: WB Saunders, 1979:1009–1088, with permission of the publisher.)

Quantitative Aspects of Bilirubin Production In healthy human subjects, bilirubin production averages approximately 4 mg/kg body weight per day (6 µmoles/kg body weight per day)

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(2,5,8,9,14,15,24,25). Hemoglobin from senescent or injured erythrocytes is the source of 80% to 85% of the heme that is eventually catabolized to bilirubin (Fig. 8.2). The remainder has multiple sources, including a component of ineffective hemoglobin production in the bone marrow and the turnover of short-lived, nonhemoglobin hemoproteins such as the various P-450 and b 5 cytochromes, catalase, and peroxidase (1,2,3,8,9,10,25,26,27,28,29,30,31). In normoblastic hemolytic anemias, the bone marrow can increase red blood cell production by as much as eightfold (32), leading to a corresponding increase in the component of bilirubin production derived from erythrocytes (3,5,27). Under these conditions, the amount of bilirubin derived from ineffective erythropoiesis in the marrow may increase P.217 in absolute terms, but the proportion of bilirubin production due to ineffective erythropoiesis remains unchanged (27,28). By contrast, major increases in the fraction of bilirubin production derived from ineffective erythropoiesis may occur in megaloblastic anemias such as those associated with either folate or vitamin B 1 2 deficiency, thalassemia, and certain dyserythropoietic anemias (27,28). Increased bilirubin production also occurs in the disorders of heme biosynthesis, including the hereditary erythropoietic porphyrias and lead poisoning (27,28,29). Finally, administration of phenobarbital and other drugs increases the turnover of heme enzymes, notably hepatic cytochrome P-450 isoforms, with a resulting increase in bilirubin production (30,31,33) (see following text).

Structure of Bilirubin-IXα Naturally occurring bilirubin is designated bilirubin-4Z,15Z-IXα. This designation indicates that it is derived from protoporphyrin isomer IX, the isomer found in heme and hemoproteins such as hemoglobin, by cleavage of the porphyrin macrocycle at the α-bridge carbon and that the stereochemical arrangement of the 4,5 and 15,16 double bonds places the 5- and 15-bridge carbons is in the Z configuration (12,34) (Fig. 8.3). This configuration allows the formation of internal hydrogen bonds between the propionic acid side chain on the B ring and polar groups on the D ring, and between the propionic acid on the C ring and polar groups on the A ring (35). Although bilirubin is frequently depicted as a linear tetrapyrrole, these hydrogen bonds in fact fix the molecule in a “ridge tile” configuration (34,36). This configuration blocks exposure of the molecule's polar groups to aqueous solvents and of the central bridge carbon to attack by diazo reagents and is therefore the basis for both bilirubin's hydrophobic behavior and its slow (indirect) diazo reactivity (reviewed in ref. 12,37) (see following text).

Other Bilirubin Isomers A number of structural (Fig. 8.4A and D) and configurational (stereo-) isomers (Fig. 8.4B and C) of bilirubin are of either physiologic or clinical interest. Opening of the protoporphyrin-IX ring at bridges other than the α-carbon can occur nonenzymatically, leading to the formation, after reduction, of bilirubin-IXβ, IXγ, or IXδ (Fig. 8.4A) (34,38). Stereoisomerization at positions 4 and 15 can lead to the formation of 4Z,15E and 4E,15E stereoisomers, respectively (12,34,39), as illustrated in Figure 8.4C and D. None of these isomers can form the internal hydrogen bonds characteristic of bilirubin-4Z, 15Z-IXα. Accordingly, they behave as more polar molecules, with rapid (direct) diazo reactivity, and can be excreted in bile without conjugation (40,41,42,43). Finally, under certain conditions in vitro, the two nonidentical halves of the bilirubin molecule can dissociate and then reassemble at random (4,12,39). This results in the formation of two symmetric isomers, designated bilirubin-IIIα and XIIIα, in addition to the asymmetric IXα isomer; the ratio of the IIIα:IXα:XIIIα molecules formed is approximately 1:2:1 (Fig. 8.4B). BilirubinIIIα and XIIIα can form internal hydrogen bonds. They are therefore relatively nonpolar, react slowly with diazo reagents, and require conjugation as a prerequisite to biliary excretion (4,11,12). Recognition of the existence and properties of these various bilirubin isomers has increased the understanding of the biologic properties of the naturally occurring 4Z, 15Z-IXα form and of the processes involved in its elimination by the liver. However, only the 4Z, 15E and 4E, 15E photoisomers, which are formed and readily excreted without conjugation during phototherapy for neonatal jaundice (41,42,43), are of clinical significance.

Bilirubin in Plasma Although the bilirubin molecule contains two carboxyls and several other polar groups, internal hydrogen bonding involving these polar moieties constrains the molecule in a rigid, nonpolar, and, therefore, highly insoluble conformation. As an otherwise insoluble molecule, bilirubin formed in the periphery is transported to the liver tightly bound to albumin, at concentrations that far exceed its solubility in protein-free aqueous solutions (44,45,46). Adult human albumin has one high-affinity binding site for bilirubin and at least one class of lower-affinity sites. Experimental measurements of the affinity of bilirubin for albumin have varied considerably with the methods employed (44), but estimates of K d for the high-affinity site have been in the micromolar range by several different approaches (44,45,47,48,49,50). The determination of these estimates has been based on the assumption that the affinity of bilirubin for albumin is constant and is independent of the albumin concentration. Under this assumption, until the bilirubin to albumin molar ratio in the circulation exceeds 1:1, virtually all the bilirubin present would be bound to the high-affinity site on albumin, and the unbound bilirubin concentration would remain extremely small. This small, unbound bilirubin concentration (51) is, nevertheless, considered to be an important driving force for hepatocellular bilirubin uptake (see following text). Under this model, if the 1:1 molar ratio of bilirubin to albumin is exceeded, the unbound bilirubin concentration increases rapidly with further increases in total bilirubin. In the neonatal period, increased levels of unbound bilirubin can cross the blood–brain barrier, leading to the serious neurologic consequences of kernicterus (52,53,54). Similar neurotoxicity may rarely occur in adolescents and P.218 adults who develop sufficiently high concentrations of unconjugated bilirubin such that the critical 1:1 bilirubin to albumin molar ratio is exceeded (55). This is, in fact, the only clinically significant potential toxicity of hyperbilirubinemia. Because the normal albumin concentration is approximately 4 g/dL (600 µM), and a 1-mg/dL bilirubin concentration represents 17.1 µM, the critical 1:1 bilirubin to albumin molar ratio is usually exceeded in otherwise healthy adults only at bilirubin concentrations of 35 mg/dL or more. In catabolic states in which hypoalbuminemia exists, however, the 1:1 ratio may be exceeded at much lower bilirubin concentrations, for example, less than 17 mg/dL in the presence of an albumin concentration of 2 g/dL. Although models of bilirubin binding to albumin that assume a constant affinity independent P.219 of the albumin concentration have been the basis for predictions of bilirubin concentrations at which the risk of kernicterus increases, several recent studies have challenged the basic assumptions of the model, reporting that the affinity of bilirubin for albumin actually varies inversely with the albumin concentration (51,56). This makes calculation of the critical unbound bilirubin concentration, and hence the risk of kernicterus, even more uncertain than earlier. However, the most rapid changes in affinity reportedly occur at quite low albumin concentrations, with only relatively minor further changes occurring as the albumin concentration is increased above 150 µM (56). Therefore, the impact of this new observation on bilirubin–albumin binding within the physiologic range of albumin concentrations, and hence on the risk of kernicterus, is yet to be definitely determined and may be very small. A variety of xenobiotics may displace or otherwise influence the binding of bilirubin to albumin. The resulting increase in the free bilirubin concentration may increase the risk of kernicterus in susceptible individuals (52,57,58,59).

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▪ Figure 8.3 Structure and conformation of bilirubin. A: Conventional “linear tetrapyrrole” structure of the naturally occurring isomer of bilirubin, designated bilirubin-IXα. The oxygen functions on the A and D rings are depicted as the lactam tautomers, and the bridge carbons at positions 5 and 15 are shown in the Z configuration. In this configuration the bridge carbons and their attached hydrogens project toward the substituted β positions on the adjacent pyrrole rings, just as in the protoporphyrin ring from which bilirubin is derived. B: Planar representation of the three-dimensional conformation of the bilirubin molecule, showing hydrogen bonding (…) between each of the –COOH side chains and the –C–O and –NH groups of the end (A and D) rings of the opposite half of the molecule. These hydrogen bonds, and weaker ones with -NH groups in the B and C rings, hold the molecule in a rigid three-dimensional conformation. C: Three-dimensional representation of bilirubin-IXα. The molecule takes the form of a ridge tile (i.e., a tile that fits along the top of a roof), with the ridge line defined by the carbons at positions 8, 10, and 12. Rings A and B lie in one plane, and C and D lie in another, with the interplanar angle being approximately 98 degrees. (Reprinted from reference Berk PD, Jones EA, Howe RB. Disorders of bilirubin metabolism. In: Bondy PK, Rosenberg LE, eds. Metabolic control and disease, 8th ed. Philadelphia: WB Saunders, 1979:1009–1088, with permission of the publisher.)

▪ Figure 8.4 Bilirubin isomers. A: Formation of α, β, γ, and δ isomers of biliverdin by nonenzymatic cleavage of the protoporphyrin ring of heme at the α-, β-, γ-, and δ-bridge carbons, respectively. B: Dipyrrolic scrambling. This process involves the nonenzymatic dissociation of the bilirubin tetrapyrrole into dipyrrolic units, which may then reassemble at random into symmetric (bilirubin-IIIα and XIIIα) and nonsymmetric (bilirubin-IXα) tetrapyrroles. When this process occurs in a mixture of the C8 and C12 isomers of bilirubin-IXα monoglucuronide, the final products will include IIIα, IXα, and XIIIα isomers of both unconjugated bilirubin and its mono- and diglucuronides. C: Nomenclature of the Z and E configurational isomers of bilirubin. If a plane is erected perpendicular to the page along the 4, 5 double bond (illustrated by the dashed lines), the B ring may be together on the same side of the plane (Z [German: Zusammen]) or on opposite sides of the plane (E [Entgegen]) from the NH group in the A ring. In the Z configuration, the meso hydrogen at position 5 is trans to the A-ring lactam hydrogen, whereas in the E configuration it is cis. D: E, Z isomerization at the 4,5 double bond. In the 4Z, 15Z configuration, the molecule is rigidly hydrogen bonded. In the 4E, 15Z configuration, the A-ring nitrogen and oxygen groups are not spatially available to form hydrogen bonds with the C12 propionic acid side chain. Because of free rotation about the C5–6 bond, the two 4E, 15Z structures are equivalent. Analogous geometric isomerization may occur at the 15, 16 double bond. (Reproduced from Berk PD. Bilirubin metabolism and the hereditary hyperbilirubinemias. In: Berk JE, Haubrich MD, Kalser MH, et al. eds. Bockus' gastroenterology, Vol. 5. Philadelphia: WB Saunders, 1985:2732–2797, with permission of the publisher.)

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Hepatic Disposition of Bilirubin Because bilirubin is a potentially toxic waste product, its hepatic disposition is designed to eliminate it from the body through the biliary tract. Transfer of bilirubin from blood to bile involves four distinct but interrelated steps: Hepatocellular bilirubin uptake, binding to specific intracellular cytosolic proteins, conjugation with glucuronic acid, and canalicular excretion (Fig. 8.5) (5,7).

Bilirubin Uptake The fenestrated endothelium that lines the hepatic sinusoids provides the bilirubin–albumin complex with ready access to the extrasinusoidal space of Disse, where it can come into direct contact with microvilli lining the sinusoidal surface of the hepatocytes (5,60,61). In this setting, bilirubin dissociates from albumin and is transported across the hepatocyte plasma membrane into the cell. Numerous in vivo studies of bilirubin uptake kinetics in animals; isolated, perfused livers; isolated hepatocytes; and plasma membrane vesicles have all indicated that bilirubin uptake is concentrative, saturable, and competitively inhibited by other organic anions such as sulfobromophthalein (BSP), implying a protein-mediated, facilitated uptake process (62,63,64,65,66,67,68,69,70,71). Subsequent reports, however, showed that BSP and bilirubin uptake could be dissociated under certain conditions, implying the existence of both shared and separate transport processes (66). Despite an intensive search, the putative bilirubin transporter has not yet been identified, and several candidate transporters (72), including such historical ones as BSP/bilirubin binding protein (BSP/BR-BP), organic anion binding protein (OABP), bilirubin translocase (BTL) (67), and the more recently reported human transporter SLC21A6 (68,69), have failed to withstand closer scrutiny. Recent studies have also identified a purely passive, nonsaturable bilirubin uptake process, but its relative magnitude compared with the saturable process remains to be determined (70). Although transportermediated hepatocellular bilirubin uptake is yet to be definitively identified, it appears that unconjugated bilirubin can be exported from the hepatocyte by the human multidrug resistance–associated protein 1 (MRP1) (71).

▪ Figure 8.5 Hepatocellular transport of bilirubin. Efficient transfer of bilirubin from blood to bile is dependent on normal sinusoidal architecture, plasma membrane transport processes, and intracellular binding and conjugation. Albumin-bound bilirubin in sinusoidal blood passes through endothelial cell fenestrae to reach the hepatocyte surface, entering the cell by both facilitated and simple diffusional processes. Within the cell it is bound to glutathione-S-transferases and conjugated by bilirubin-uridine-5′-diphosphateglucuronosyltransferase (UGT1A1) to monoglucuronides and diglucuronides, which are actively transported across the canalicular membrane into the bile. ALB, albumin; UCB, unconjugated bilirubin; BT, proposed bilirubin transporter; GST, glutathione-S-transferase; BMG, bilirubin monoglucuronide; BDG, bilirubin diglucuronide; MRP2, multidrug resistance–associated protein 2. (Reproduced from Berk PD, Wolkoff AW. Bilirubin metabolism and the hyperbilirubinemias. In: Braunwald E, Fauci AS, Kasper DL, et al. eds. Harrison's principles of internal medicine, 15 ed. New York: McGraw-Hill, 2001:1715–1720, with the permission of the publisher.)

Intracellular Binding Once within the cell, bilirubin partitions between the cytosol and the lipid bilayer of various intracellular membranes. As with bilirubin binding to albumin P.221 in plasma, the cytosolic bilirubin fraction is kept in solution at concentrations that far exceed its aqueous solubility by binding as a nonsubstrate ligand to a number of proteins, of which the most abundant and best characterized are members of the glutathione-S-transferase (GST) superfamily (73,74). This family includes a large number of homodimeric and heterodimeric proteins, previously referred to as ligandins (75), that are principally responsible for bilirubin binding. Kinetic analyses suggest that binding to these proteins is not involved in the initial process of cellular bilirubin uptake but does increase net bilirubin sequestration by decreasing bilirubin efflux from the cytosol back into the space of Disse (76). The GSTs have been postulated to play a specific role in presenting bilirubin to the microsomes for subsequent conjugation (4,72).

Bilirubin Glucuronidation The aqueous insolubility of bilirubin reflects the rigid, highly ordered, molecular structure conferred by internal hydrogen bonding that prevents solvent access to polar components of the molecule. Subsequent conjugation with glucuronic acid residues disrupts this internal hydrogen bonding, rendering the resulting monoglucuronide and diglucuronide conjugates highly soluble in aqueous solutions. The enzyme responsible for bilirubin glucuronidation is the uridine-5′-diphosphate glucuronosyltransferase isoform 1A1 (UGT1A1), which is encoded by the UGT1 gene on chromosome 2 (77). This gene has a complex structure, and mutations within it are recognized as the cause of three different disorders characterized by unconjugated hyperbilirubinemia: Gilbert's syndrome and Crigler-Najjar syndrome types I and II. The UGT1 gene (Fig. 8.6) (7) consists of 13 exons (designated A1 to A13) each of which encodes a distinct, substrate-specific binding site for one of the multiple protein isoforms produced by this single gene locus. Initiation of ribonucleic acid transcription at each of these 13 exons is controlled by a separate promoter element immediately upstream of its unique exon. Alternative splicing fuses one of these upstream exons with the four exons (exons 2 to 5) common to all UGT1 protein isoforms. Exon A1 and the four common exons code for the UGT1A1 protein that is responsible for glucuronidation of bilirubin (78) (Fig. 8.6).

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▪ Figure 8.6 Structural organization of the human UGT1 gene complex. This large complex on chromosome 2 contains at least 13 substratespecific first exons (A1, A2, etc.), each with its own promoter, that encode the N-terminal substrate-specific 286 amino acids (AAs) of the various UGT1-encoded isoforms, and common exons 2 to 5 that encode the 245 carboxyl-terminal amino acids common to all the isoforms. Messenger ribonucleic acids (mRNAs) for specific isoforms are assembled by splicing a particular first exon such as the bilirubin-specific exon A1 to exons 2 to 5. The resulting message encodes a complete enzyme, in this particular case bilirubin-uridine-5′-phosphateglucuronosyltransferase (UGT1A1). Mutations in a first exon affect only a single isoform. Those in exons 2 to 5 affect all enzymes encoded by the UGT1 complex. (Reprinted from Berk PD, Wolkoff AW. Bilirubin metabolism and the hyperbilirubinemias. In: Braunwald E, Fauci AS, Kasper DL, et al. eds. Harrison's principles of internal medicine, 15 ed. New York: McGraw-Hill, 2001:1715–1720, with permission of the publisher.)

Canalicular Excretion of Bilirubin Bilirubin glucuronides are transported across the apical plasma membrane into the canaliculus by an adenosine triphosphate (ATP)-dependent process mediated by a membrane protein initially called canalicular multispecific organic anion transporter (cMOAT), but now designated MRP2 (Fig. 8.5) (79,80). MRP2 is a member of the MRP gene family, other members of which pump drug conjugates, as well as unmodified anticancer drugs, out of cells. In mouse models, effective MRP2 function requires the presence of at least one additional protein, radixin, which localizes to the canalicular membrane and directly binds the carboxyl-terminal cytoplasmic domain of MRP2 (81). P.222

Fate of Bilirubin in the Gastrointestinal Tract Conjugated bilirubin excreted in bile passes through the small intestine without significant absorption and reaches the colon intact (82,83,84,85). There, it is both deconjugated, presumably by bacterial β-glucuronidases (86), and degraded by other bacterial enzymes to a large series of urobilinogens and other products (87,88,89,90), the nature and relative proportions of which depend in part on the bacterial flora (84,91,92). Because of this variability, quantitation of fecal urobilinogen excretion does not provide an accurate measure of heme degradation and bilirubin formation (93) and has largely been abandoned as a clinical test for hemolysis or ineffective erythropoiesis. Some urobilinogen is reabsorbed from the colon (94), resulting in small but measurable concentrations of urobilinogen in plasma (95). Most of this is re-excreted by the liver, but a small fraction is eliminated by the kidney. Increased urinary excretion of urobilinogen is a consequence of its increased plasma level. This in turn may reflect either increased bilirubin production, with a consequent increased formation and enterohepatic circulation of urobilinogen, or decreased hepatic clearance of urobilinogen. Hence, an elevated urine urobilinogen excretion does not distinguish between hemolysis and liver disease (96). In the neonatal period, the presence of increased levels of intestinal β-glucuronidase (84,97) may result in the presence of appreciable amounts of unconjugated bilirubin within the distal small intestine and upper colon. Absorption from these sites can give rise to a significant enterohepatic circulation of unconjugated bilirubin (82,83,84), which has been implicated as a contributing factor to physiologic jaundice in the newborn and to the further increase in plasma bilirubin concentrations seen in neonates with intestinal obstruction, delayed passage of meconium, or fasting (86). In severe unconjugated hyperbilirubinemias such as those occurring in Crigler-Najjar syndrome type I or in the jaundiced Gunn rat (see following text), a similar enterohepatic circulation may result from unconjugated bilirubin being excreted both in bile (98,99) and directly across the intestinal lumen into the gut (98). Efforts to reduce unconjugated hyperbilirubinemia in such situations by interrupting the enterohepatic circulation of unconjugated bilirubin with the use of agents such as oral agar, charcoal, or cholestyramine have had at best limited and inconsistent success (84,86,100). Recent reports suggest that oral administration of calcium phosphate with or without the lipase inhibitor orlistat may be an efficient means to interrupt bilirubin enterohepatic cycling to reduce serum bilirubin levels (101,102).

Bilirubin in the Urine Because of its very tight binding to albumin, the free fraction of unconjugated bilirubin in plasma is too small to permit efficient ultrafiltration at the glomerulus. Consequently, unconjugated bilirubin never appears in the urine no matter what its plasma concentration. By contrast, bilirubin conjugates are appreciably less tightly albumin bound. In the presence of cholestasis, whether secondary to hepatocellular injury or ductal obstruction, bilirubin conjugates formed in the hepatocyte are diverted back to the circulation, where their weaker albumin binding and larger free fraction permit excretion by the kidney, principally by glomerular filtration (103,104,105,106,107). A small degree of tubular reabsorption has been demonstrated, but tubular secretion apparently does not occur (107). The presence of bilirubin in the urine is an absolute indicator of conjugated hyperbilirubinemia.

Clinical Physiology of Bilirubin The quantity of unconjugated bilirubin in plasma, and hence the plasma unconjugated bilirubin concentration, reflects a balance between two processes: Bilirubin production and hepatic bilirubin clearance (Fig. 8.7) (5,24,27,108). This balance is indicated by the relationship: BR [not asymptotically equal to] BRT/C B R , where BR represents the plasma unconjugated bilirubin concentration, BRT is plasma bilirubin turnover (which closely approximates bilirubin production), and C B R is the rate of clearance of unconjugated bilirubin from plasma by the liver. Measurement of C B R , in units of milliliter per minute per kilogram, is a quantitative test of hepatic function that is, conceptually, analogous to creatinine clearance, a widely used measure of renal function. Both BRT and C B R can be calculated from the area under the curve of an injected tracer dose of radiolabeled unconjugated bilirubin (24,27,108,109). Alternatively, the bilirubin production rate can be estimated by isotope dilution from the specific activity of fecal bile pigments after an intravenous injection of radiolabeled bilirubin (25,26,110), or from measurements of the excretion rate of CO (15,111,112). Although estimates of BRT and C B R by any of these methods are not available as routine clinical measurements, an appreciation of the physiologic implications of these two variables is very useful in interpreting data that are readily available in clinical settings. Specifically, the equation indicates that BR is directly proportional to the rate of bilirubin turnover and inversely related P.223 to hepatic bilirubin clearance in a manner analogous to the relationship between glomerular filtration rate and serum creatinine. Moreover, starting from any given baseline values of BRT and C B R , a change in either BRT or C B R will result in a corresponding fractional change in BR. The fractional change in BR will be directly proportional to any fractional change in BRT and inversely proportional to a fractional change in C B R (Figs. 8.7 and 8.8) (27,108). As a result, for any given level of bilirubin production, equal fractional changes in hepatic bilirubin clearance can have dramatically different effects on plasma bilirubin concentrations, depending on the initial absolute value of C B R . For example, when bilirubin turnover is normal (e.g., 4 mg/kg per day), reducing bilirubin clearance from a normal mean value of 0.70 mL/minute/kg to a lower mean value of 0.35 mL/minute/kg (a reduction of 50%) will approximately double the serum bilirubin concentration, increasing it by approximately 0.4 mg/dL (from 0.4 to 0.8 mg/dL). This increment may well go unnoticed clinically. By comparison, in a patient whose hepatic clearance is already reduced, a corresponding 50% reduction in bilirubin clearance, for example, from 0.1 to 0.05 mL/minute/kg, will again double the bilirubin concentration. In this instance, however, the interval increase, by approximately 2.7 mg/dL, will be sufficient to be clinically detectable. Similarly, doubling bilirubin production will double the plasma concentration of unconjugated bilirubin. The absolute magnitude of the increase, in milligram per deciliter, will depend on the value of C B R .

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▪ Figure 8.7 Relationship between plasma bilirubin turnover (BRT), hepatic bilirubin clearance (C B R ), and the plasma concentration of unconjugated bilirubin (BR). Stippled area represents the normal range for bilirubin turnover; bar on the horizontal axis is the normal range (mean ± 2 standard deviations) for C B R . (Reprinted from Berk PD, Martin JF, Blaschke TF, et al. Unconjugated hyperbilirubinemia. Physiologic evaluation and experimental approaches to therapy. Ann Intern Med 1975;82:552–570, with permission of the publisher.)

Measurement of Plasma Bilirubin Concentration Plasma bilirubin is typically measured in clinical laboratories by some modification of the diazo reaction first described by van den Bergh and Müller in 1916 (113) (reviewed in ref. 114). In this procedure, unconjugated P.224 bilirubin in the sample reacts slowly with the diazo reagent (e.g., diazotized sulfanilic acid) because the central bridge carbon, which is the site of the attack by the reagent, is rendered sterically inaccessible by internal hydrogen bonding within the molecule (Fig. 8.3). In the presence of ethanol, caffeine, or other “accelerators” that disrupt the internal hydrogen bonding, the central bridge carbon becomes more readily accessible to nucleophilic attack and the unconjugated bilirubin molecule reacts more rapidly and completely. Similarly, rapid diazo reactivity is displayed by conjugated bilirubin, in which esterification of propionic acid side chains with glucuronic acid prevents hydrogen bond formation and exposes the central bridge carbon. Accordingly, the “prompt” or direct-reacting bilirubin in serum or plasma, considered a measure of the amount of conjugated bilirubin present, is determined a short time (30 to 60 seconds) after the addition of the diazo reagent to the sample in the absence of an accelerator. The total bilirubin concentration, a measure of both unconjugated and conjugated bilirubin, is typically measured at some more prolonged interval (e.g., 30 to 60 minutes) after addition of an accelerator substance. The indirect-reacting bilirubin, calculated as the difference between the total and the direct-reacting bilirubin, is widely used as a proxy for the amount of unconjugated bilirubin in the sample (114).

▪ Figure 8.8 Relationship between plasma bilirubin turnover and the plasma concentration of unconjugated bilirubin. Normal plasma bilirubin turnover is up to 5 mg/kg body weight per day. Higher values indicate increased bilirubin production, usually from hemolysis. When hepatic bilirubin clearance is within the normal range, the plasma unconjugated bilirubin concentration increases linearly with increases in bilirubin turnover, as indicated by the regression line (the stippled area represents ± 2 standard errors of the estimate about the regression line). Extrapolation of the regression line to the maximal rate of steady state bilirubin production indicates the highest level of unconjugated hyperbilirubinemia that can result from sustained hemolysis in an individual with normal hepatic bilirubin clearance. Because the bone marrow can increase erythrocyte production only by about eightfold in response to hemolysis, the maximum sustainable rate of bilirubin turnover is approximately 40 mg/kg per day, and the corresponding value of plasma unconjugated bilirubin is 4 mg/dL. (Reproduced from Berk PD, Martin JF, Blaschke TF, et al. Unconjugated hyperbilirubinemia. Physiologic evaluation and experimental approaches to therapy. Ann Intern Med 1975;82:552–570, with permission of the publisher.)

Bilirubin can also be estimated in biologic fluids by direct spectrophotometry because of its intense absorption band at approximately 450 nm (12,115). The method is rapid, requires very small samples, and is therefore often used in neonatal nurseries or in amniotic fluid analyses (116) in which sample availability is limited. The method is nonspecific because turbidity and other yellow–orange materials such as carotenoids interfere. Various devices designed to measure bilirubin levels transcutaneously without blood sampling, by reflectance and/or spectrophotometry, are widely used in neonatal nurseries (see for example ref. 117). Accurate alternative methods also exist for the quantification of individual bilirubin species (118,119), including bilirubin conjugates covalently bound to plasma proteins (i.e., δ-bilirubin, see following text), not only in plasma but also in bile, urine, and other biologic P.225 fluids (120,121,122,123,124,125). Because they are rarely employed outside research laboratories, a description of these technologies is beyond

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the scope of this review.

Normal Ranges Using conventional, diazo-based analytic procedures, the upper limit of normal for total plasma bilirubin has been reported to be anywhere between 1.0 and 1.5 mg/dL (17 and 26 µM), and that for the indirect-reacting fraction between 0.8 and 1.2 mg/dL (14 and 21 µM) (2,96,114,126,127). Differences reported reflect both variations in analytic methods and whether the 95% or 99% confidence limit was used to define the normal range. They also reflect the fact that bilirubin concentrations in the healthy population exhibit a log-normal (skewed to the right) rather than a Gaussian (bell-shaped) distribution, which must be accounted for in establishing appropriate normal limits (126). Many studies have set the upper limit of normal for the indirect-reacting fraction at 1.0 mg/dL (17 µM), which is in close agreement with the limits predicted on theoretic grounds from knowledge of the distribution of plasma bilirubin turnover and hepatic bilirubin clearance rates in a healthy population (126). When the total plasma bilirubin concentration is normal, the normal direct-reacting fraction (a proxy for conjugated bilirubin) is traditionally reported to be less than 0.1 mg/dL, or at most less than 0.2 mg/dL (114). Because unconjugated bilirubin does react, although slowly, with diazo reagents even in the absence of an accelerator, even this small direct-reacting fraction overestimates the miniscule amounts of conjugated bilirubin actually present (125). Consequently, the calculated indirect-reacting bilirubin underestimates the amount of unconjugated bilirubin present. The proportional magnitude of these errors is greatest at total bilirubin concentrations within or near the normal range. Nevertheless, at virtually any total bilirubin level, if the direct-reacting fraction is less than 15% of the total, the bilirubin in the sample can be considered essentially as being completely unconjugated. Unfortunately, the errors involved appear to be greater with autoanalyzer methods currently in widespread use than they were with manual methods used in the past. “Normal” values for direct-reacting bilirubin have been creeping upward over the years even as more precise chromatographic methods demonstrate that the actual amounts of conjugated bilirubin in normal serum or plasma are vanishingly small. An informal survey several years ago suggested that few large laboratories in the New York metropolitan area set an upper limit of normal for direct-reacting bilirubin as low as 0.2 mg/dL. The most commonly reported upper limit was 0.3 mg/dL, with limits of 0.4 to 0.8 mg/dL being reported not infrequently. Such latitude can lead to considerable error in interpreting the direct- and indirect-reacting fractions as conjugated and unconjugated bilirubin, respectively. Because the presence of even modest amounts of true conjugated bilirubin in serum should alert the clinician to the possibility of significant hepatobiliary pathology, this distinction is of more than academic interest (128). Because conventional bilirubin glucuronide conjugates are water soluble and bind relatively loosely to albumin, they are readily filtered at the glomerulus and excreted in the urine. Accordingly, uncertainty about the clinical significance of a mildly elevated level of direct-reacting bilirubin can often be clarified by a simple dipstick test for bilirubin in the urine. Even minimal degrees of conjugated hyperbilirubinemia are associated with bilirubinuria. A negative dipstick test in the presence of a modestly elevated direct-reacting fraction suggests the presence of either δ-bilirubin (see following text) or an artifact of the diazotization procedure. With prolonged conjugated hyperbilirubinemia, some of the conjugated bilirubin in plasma binds covalently to albumin and produces what is designated the δ-bilirubin fraction (121,122,123,124). Although δ-bilirubin gives a direct diazo reaction, it is not filterable by the glomerulus and does not appear in the urine; it disappears slowly from the plasma with the 14- to 21-day half-life of the albumin to which it is bound. δ-Bilirubin accounts for the sometimes slow rate with which conjugated (direct) hyperbilirubinemia resolves as hepatitis improves or biliary obstruction is relieved. Although δ-bilirubin is not easily measured, its presence can be inferred when an elevated level of direct-reacting bilirubin persists after bilirubinuria resolves.

Hyperbilirubinemia and Jaundice Hyperbilirubinemia is conveniently classified as unconjugated (indirect-reacting), or conjugated (direct-reacting) hyperbilirubinemia. In practice, pure conjugated hyperbilirubinemia is uncommon; in most cases an elevated plasma conjugated bilirubin level is accompanied by an elevation of the unconjugated bilirubin level, resulting in mixed hyperbilirubinemia. In this setting, because the plasma level of conjugated bilirubin reflects renal as well as hepatic clearance of bilirubin conjugates, the ratio of conjugated to total bilirubin is usually not helpful diagnostically. Another useful characteristic is whether hyperbilirubinemia is the only abnormality of hepatic function or whether other hepatic biochemical tests such as the activities of serum aminotransferases (alanine aminotransferase [ALT], aspartate aminotransferase [AST]), alkaline phosphatase, or γglutamyltransferase are also abnormal. Absence of abnormalities of other hepatic biochemical tests is one of the features that helps distinguish the familial P.226 hyperbilirubinemias from most acquired cases of hyperbilirubinemia. However, certain forms of acquired hyperbilirubinemia such as acquired hemolytic disease and inactive cirrhosis may also occur in the absence of other biochemical abnormalities. The major causes of familial hyperbilirubinemia are listed in Table 8.1.

Table 8.1. The Familial Hyperbilirubinemias

I. Unconjugated hyperbilirubinemias A. From increased bilirubin production 1. Hemolytic anemias a. Hemoglobinopathies b. Thalassemia syndromes c. Enzyme defects d. Membrane defects, etc. 2. Shunt hyperbilirubinemias a. Congenital dyserythropoietic jaundice syndromes b. Miscellaneous B. From defective hepatic bilirubin clearance 1. Gilbert's syndrome 2. Crigler-Najjar syndrome a. Type I—phenobarbital resistant b. Type II—phenobarbital responsive II. Conjugated hyperbilirubinemias A. Dubin-Johnson syndrome B. Rotor's syndrome

Causes and Consequences of Hyperbilirubinemia Unconjugated hyperbilirubinemia Unconjugated hyperbilirubinemia is the result of any process that increases bilirubin production, decreases bilirubin clearance, or results in both processes acting in concert (3,27,108,109). The reference range for the plasma unconjugated (i.e., indirect-reacting) bilirubin concentration is generally reported to be 0.3 to 1.0 mg/dL, although some laboratories set the upper limit at 1.2 mg/dL and occasionally as high as 1.5 mg/dL. Values above the reference range represent unconjugated hyperbilirubinemia. Although scleral icterus may become detectable when the bilirubin concentration exceeds 2.5 to 3.0 mg/dL, many cases of unconjugated hyperbilirubinemia are subclinical and detectable only by measurement of the plasma bilirubin concentration.

Increased bilirubin production Hemolysis and increased ineffective erythropoiesis are two of the most common processes responsible for increased bilirubin production. A large number of distinct hereditary hemolytic disorders have been described (129) and result from inherited hemoglobinopathies, enzyme deficiencies,

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or abnormalities in red blood cell membrane structure. There are also many acquired hemolytic conditions, ranging from pure, specific autoimmune hemolytic anemias to the shortened red cell life spans that accompany many chronic diseases. Excessive ineffective erythropoiesis may occur on a congenital basis, as in any subtype of congenital dyserythropoietic anemia (3,5,28), or on an acquired basis, in disorders such as erythropoietic porphyria, pernicious anemia, and lead poisoning (2,29,129). Transfusion of old bank blood and massive hematomas or pulmonary infarcts can produce unconjugated hyperbilirubinemia by temporarily increasing bilirubin production. Excessive hepatic bilirubin production, although seemingly a potential cause of increased plasma bilirubin turnover, has not been convincingly documented as a cause for clinically evident hyperbilirubinemia. Although hepatic heme turnover has been reported to contribute as much as one fourth of the total bilirubin production on the basis of the labeling of plasma bilirubin after administration of radiolabeled heme precursors (see for example refs 130–132), approximately half of hepatic-derived bilirubin is excreted into the bile without transit through the plasma (2,5,24,25,27,110,131,133). This means that hepatic hemes contribute no more than approximately 12% of the plasma bilirubin turnover. Studies documenting a significant discrepancy between the increase in bilirubin labeling from 3 H- or 1 4 C-labeled heme precursors and total bilirubin production suggest that the actual percentage of plasma bilirubin turnover derived from hepatic hemes is appreciably lower (134,135). On this basis, hepatic heme turnover would have to increase manyfold to result in a clinically recognizable increase in the plasma unconjugated bilirubin concentration. Unconjugated hyperbilirubinemia solely due to increased bilirubin production rarely exceeds 4 mg/dL, even in the face of brisk hemolysis (Fig. 8.8) and is generally well tolerated. However, subjects are at an increased risk for the development of pigmented gallstones.

Decreased bilirubin clearance As noted in preceding text, four distinct processes are involved in hepatocellular bilirubin disposition, and each, if defective, can result in a decrease in hepatic bilirubin clearance. Although the precise mechanism(s) by which bilirubin is taken up by hepatocytes remains unclear, several drugs (e.g., rifampin, flavispidic acid, novobiocin, and various cholecystographic contrast agents) are reported to competitively inhibit the bilirubin uptake process (see ref. 5). The resulting unconjugated hyperbilirubinemia resolves with the cessation of the medication. Reduced hepatic bilirubin uptake (and net clearance) can also result from portosystemic shunting by which blood bypasses the hepatocytes. Although this is most commonly thought P.227 of as occurring through venous channels such as varices, it may also result from capillarization of the hepatic sinusoids—that is, the loss of sinusoidal endothelial fenestrae and increased perisinusoidal matrix deposition—that occurs in cirrhosis. It is also a consequence of an absolute reduction in hepatic blood flow or of abnormalities in the net extraction of bilirubin from the circulation by hepatocytes.

▪ Figure 8.9 Relationship between the mean values for hepatic bilirubin clearance (C B R ) and bilirubin uridine-5′-diphosphateglucuronosyltransferase (UDPGT) activity in patients with Crigler-Najjar syndrome type I, Gilbert's syndrome, and healthy controls. For the control group, data are presented for both untreated and phenobarbital-treated subjects. The line represents a least-squares fit to the mean values for the four groups. Subsequent data in Crigler-Najjar type II fell on the regression line. Data such as these suggested that Gilbert's syndrome and the two Crigler-Najjar syndromes might all reflect mutations with quantitatively differing effects on a single gene, designated at the time as bilirubin-UDP-glucuronyltransferase. (Modified from Blaschke TF, Berk PD, Rodkey FL, et al. Drugs and the liver. I. Effects of glutethimide and phenobarbital on hepatic bilirubin clearance, plasma bilirubin turnover and carbon monoxide production in man. Biochem Pharmacol 1974;23:2795–2806.)

Abnormalities in the binding of bilirubin to its cytosolic binding proteins are at least a hypothetical basis for decreased bilirubin clearance. However, defective glucuronidation is a more common mechanism that results in reduced bilirubin clearance and consequent unconjugated hyperbilirubinemia. Delayed expression of UGT1A1 in neonates is primarily responsible for the physiologic jaundice of otherwise healthy newborns. Peak serum bilirubin levels in this setting are typically less than 5 to 10 mg/dL between days 2 and 5 and decline to normal within 2 weeks. Higher neonatal bilirubin levels that predispose to kernicterus occur in the face of profound prematurity, Gilbert's syndrome (see following text), hemolysis, or both (see for example ref. 136). Three familial disorders of bilirubin conjugation are well recognized: Crigler-Najjar syndrome types I and II and Gilbert's syndrome. These are described in greater detail in following text. Although considered until recently as distinct disorders, these conditions are all now known to result from mutations of different functional severity in the bilirubin-conjugating enzyme UGT1A1. Acquired deficiency of UGT1A1 and consequent unconjugated hyperbilirubinemia also occurs with administration of certain human immunodeficiency virus protease inhibitors such as indinavir and atazanavir (reviewed in ref. 137,138).

Conjugated hyperbilirubinemia Conjugated hyperbilirubinemias typically reflect abnormalities in hepatocellular excretion of conjugated bilirubin or in biliary tract obstruction. Dubin-Johnson and Rotor's syndromes are uncommon, heritable disorders of conjugated bilirubin excretion. In Dubin-Johnson syndrome, mutations in MRP2 result in deficient canalicular transport of bilirubin conjugates (80,139,140). The molecular defect in Rotor's syndrome remains unknown but produces a phenotype similar in many respects to that of Dubin-Johnson. In both disorders, general hepatocellular function is preserved and liver chemistries other than the bilirubin P.228 concentration are typically normal. Bilirubin concentrations in Dubin-Johnson and Rotor's syndromes are most often between 2 and 5 mg/dL, although values as high as 5 mg/dL for prolonged periods have been described. Extensive clinical experience suggests that conjugated hyperbilirubinemia produces no significant adverse consequences, even if prolonged for months at levels of up to 35 to 40 mg/dL. Far more common is the defective bilirubin excretion that occurs with a broad spectrum of hepatobiliary diseases. In these conditions, elevations in bilirubin concentration typically occur in association with abnormalities of other hepatic biochemical tests, including elevations in AST and ALT levels, alkaline phosphatase level, and, if severe, reduction in serum albumin level and prolongation of clotting times. This broad category of diseases includes hepatocellular and cholestatic liver diseases, benign postoperative jaundice, mechanical intrahepatic or extrahepatic bile duct obstruction, and a rare group of disorders classified under the rubric of familial intrahepatic cholestasis (141).

Familial Hyperbilirubinemias

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The Familial Unconjugated Hyperbilirubinemias The spectrum of familial unconjugated hyperbilirubinemias is indicated in Table 8.2. This review limits itself to those entities associated with a decrease in hepatic bilirubin clearance: Crigler-Najjar syndrome types I and II and Gilbert's syndrome. Important characteristics of these three entities are summarized in Table 8.2. These were once considered distinct genetic and pathophysiologic entities, with Gilbert's syndrome reportedly an autosomal dominant disorder and Crigler-Najjar type I an autosomal recessive disorder (see for example refs 2,4,5). However, physiologic observations (Fig. 8.9) (142) suggested that the three entities might reflect mutations with quantitatively different impact on the functioning of a single gene. Subsequent molecular findings in the specific syndromes and the observation that one normal UGT1A1 allele is sufficient to maintain a normal plasma bilirubin concentrations (77,78) have established that in almost all instances the hereditary unconjugated hyperbilirubinemias are related autosomal recessive disorders.

Crigler-Najjar syndrome type I Crigler-Najjar syndrome type I is a rare, recessive disorder characterized by profound unconjugated hyperbilirubinemia, with bilirubin concentrations of 20 to 45 mg/dL as a result of mutations in UGT1A1 that result in the near total loss of UGT1A1 enzyme activity (77,78,100,143,144,145,146,147,148,149,150,151). Mutations most often occur in exons 2 to 5 of the UGT1 gene, affecting the glucuronidation of a wide spectrum of substrates in addition to bilirubin (type Ia). Less often, the mutation occurs in exon 1, and the loss of glucuronidation capacity is largely limited to bilirubin conjugation (type Ib). Crigler-Najjar syndrome type I first appears in the neonatal period, and historically, most patients have succumbed from kernicterus in infancy and early childhood. Patients with Crigler-Najjar syndrome type I do not respond to phenobarbital with a reduction in plasma bilirubin concentrations (2,4,6,8,9,10,11,100,146). Although survival has been extended with the advent of phototherapy, those who survive beyond early childhood remain at substantial risk for late-onset bilirubin encephalopathy, which often sets in after even mild febrile illnesses (see for example refs 100,152). Although isolated hepatocyte transplantation has been used experimentally in a limited number of cases of Crigler-Najjar syndrome type I (153,154), early liver transplantation remains the best hope to prevent brain injury and death (155,156,157,158). Much of the basis for elucidation of the pathobiology of Crigler-Najjar syndrome type I has arisen from studies that have been performed in the Gunn rat. This mutant Wistar strain of rats was initially described by Gunn in 1938 as having chronic nonhemolytic unconjugated hyperbilirubinemia (159). As in patients with Crigler-Najjar syndrome type I, jaundice in these animals is inherited as an autosomal recessive trait. Heterozygotes are anicteric, and liver histology in the affected rats is normal. Bilirubin glucuronyl transferase activity is undetectable in the livers of these rats (160).

Crigler-Najjar syndrome type II In contrast to Crigler-Najjar type I, in Crigler-Najjar type II UGT1A1 activity is maintained, although at a minimal level (80% isomer I

Markedly increased total; isomer I increased, but

tests

coproporphyrins

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always Table of Contents > Volume I > Section II - General Considerations > Chapter 9 - Hepatic Histopathology

Chapter 9 Hepatic Histopathology Zachary D. Goodman Hala R. Makhlouf

Key Concepts z

Histopathologic examination of a liver biopsy specimen is a source of otherwise unobtainable qualitative information about the structural integrity of the liver tissue, the type and degree of injury, and the host's response to the injury; histopathologic examination also provides a basis for the diagnosis and classification of tumors.

z

z

Histochemical and immunohistochemical stains are extremely helpful in evaluating the liver biopsy specimen. Qualitatively different patterns of injury can be used to distinguish diseases that have similar clinical presentations, such as chronic hepatitis, alcoholic or nonalcoholic steatohepatitis, and chronic cholestatic syndromes.

z

Specific histologic features may allow precise diagnosis or strongly suggest a specific diagnosis. For example, “ground-glass” cells with positive histochemical or immunostaining for hepatitis B surface antigen indicates chronic hepatitis B infection, or florid duct lesions indicate the early stage of primary biliary cirrhosis.

z

Accurate classification of tumors almost always requires histologic examination of tissue obtained by either biopsy or surgical excision.

The liver biopsy is an essential part of the investigation of diseases of the liver. Percutaneous (sometimes laparoscopic or transjugular) needle biopsies provide most of the specimens and the greatest challenge to the surgical pathologist, but open surgical biopsies and resection specimens obtained at laparotomy are also seen from time to time, especially when dealing with tumors, and even in total hepatectomies in

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liver transplantation centers. Despite the many advances in laboratory tests, molecular diagnosis, and radiologic imaging techniques, liver biopsies continue to be performed. This is because histopathologic examination of the biopsy specimen is a source of otherwise unobtainable qualitative information about the structural integrity of the liver tissue, the type and degree of injury, and the host's response to the injury; histopathologic examination also provides a basis for the diagnosis and classification of tumors. Liver biopsy should only be performed after a thorough noninvasive clinical evaluation. Furthermore, this information, including a history of possible exposure to hepatotoxins and sources of infection, pertinent physical findings, laboratory tests of liver function and integrity, serologic tests to detect infectious agents and autoimmunity, and radiologic studies, when appropriate, should be made available to the pathologist. Many biopsy specimens can be interpreted solely on morphologic grounds, and we recommend that the pathologist first examine the specimen and make initial observations without being biased by the clinical impression and laboratory data. However, after these initial observations, we strongly recommend that the P.246 pathologist review the clinical and laboratory data, preferably with the clinician, and then arrive at the best possible clinical–pathologic correlation as the definitive diagnosis. This will allow the pathologist to avoid embarrassing errors that result from lack of information and will, at the same time, provide the clinician with an interpretation that will allow optimal patient care. In that regard, this chapter emphasizes the morphologic (predominantly light microscopic) aspects of the diseases of the liver, with clinical correlations in some of the major diseases.

Systematic Approach to the Liver Biopsy The observer evaluating a liver biopsy specimen should always use a systematic approach to histopathologic evaluation. All fragments from a given biopsy specimen should be examined because a focal lesion, such as a granuloma, can be easily missed. In an architecturally normal liver it is best to begin evaluating by locating the terminal hepatic venules (or “central” veins) and then move in the direction of the portal areas. In doing so, changes involving the veins themselves and then the liver cells, bile canaliculi, abnormal deposits in spaces of Disse (e.g., collagen, amyloid), hypertrophied stellate cells, the sinusoids and their contents, and the Kupffer cells should be specifically looked for. The plates of hepatocytes nearest the portal areas should receive special attention, particularly in chronic necroinflammatory or cholestatic disorders. Proliferation of ductules and fibrosis also occur in this region of the acinus. All structures of the portal areas, namely, the connective tissue, bile ducts, veins, arteries, and lymphatics, as well as the inflammatory response (e.g., granulomas and the various types and

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relative proportions of inflammatory cells), should be examined. In addition to searching for specific lesions, the absence of various structures in the portal areas such as the destruction and disappearance of bile ducts in primary biliary cirrhosis (PBC) or the obliteration of veins in hepatoportal sclerosis should also be carefully noted.

▪ Figure 9.1 The Masson trichrome stains type I collagen blue, revealing zone 3 fibrosis in this case of alcoholic liver disease. An occluded terminal hepatic venule can be seen in the center of the field.

Special Histochemical Stains Although most of the observations that lead to a diagnosis are made using the routine hematoxylin and eosin stain, special stains are helpful in evaluating liver biopsy specimens. Staining methods referred to in this chapter can be found in the Armed Forces Institute of Pathology's Laboratory Methods in Histotechnology (1).

Fibrosis and connective tissue Evaluation of the presence, extent, and location of fibrosis is essential in the diagnosis of non-neoplastic liver disease. A Masson trichrome (Fig. 9.1) is useful for demonstrating the degree of fibrosis and cirrhosis in chronic liver disease and is also useful in assessing changes involving arteries and veins, such as the lesions of veno-occlusive disease and hepatic vein thrombosis. A Movat pentachrome stain is particularly useful for vascular lesions because it stains elastica and P.247 acid mucopolysaccharide, in addition to collagen and smooth muscle (Fig. 9.2). Elastic tissue can also be well demonstrated by orcein or

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Victoria blue stains that are used to identify ground-glass cells containing hepatitis B surface antigen. A reticulin stain is useful for outlining areas of focal or zonal necrosis (Fig. 9.3), thick liver plates, or nodules of regeneration. It can also be used to demonstrate fibrosis, but in general the Masson stain is preferred because the reticulin stain does not distinguish permanent scarring from stromal collapse.

▪ Figure 9.2 The Movat pentachrome stain shows a partially occluded outflow vein in this case of alcoholic cirrhosis. The elastic tissue in the wall of the vein is black, whereas mucopolysaccharides in the hypertrophied intima are pale blue, and collagen in the cirrhotic scars is yellow green.

Complex carbohydrates Complex carbohydrates are readily demonstrated with the periodic acidSchiff (PAS) stain. This will of course demonstrate glycogen in liver cells or in benign and malignant hepatocellular tumors, but a much more useful stain that should be routinely employed is the PAS stain after pretreatment with diastase (DPAS) to remove the glycogen and unmask other complex carbohydrate–containing substances, including metabolic and synthetic products of the liver, and structural components. The DPAS stain strikingly demonstrates the presence of lipofuscin and other cell debris in Kupffer cells and portal macrophages in acute hepatocellular injury (Fig. 9.4). The Dubin-Johnson pigment in liver cells stains variably with PAS. In type IV glycogenosis, Lafora's disease (myoclonus epilepsy), and cyanamide-induced liver injury, hepatocytes (mainly in zone 1) contain PAS-positive material that resists diastase digestion, but in Lafora's disease and glycogenosis type IV the material can be digested by pectinase. The globules of α 1 -

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antitrypsin are strongly DPAS positive (Fig. 9.5). PAS is also useful for staining bile duct basement membranes, to demonstrate ductal injury; fibrin (e.g., in disseminated intravascular coagulation); amyloid; starch; amoebae; and most pathogenic fungi.

▪ Figure 9.3 The reticulin stain shows the black-staining type III collagen fibers that support the liver cell plates. A terminal hepatic venule in the center of the field is surrounded by collapsed reticulin, indicating zone 3 necrosis.

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▪ Figure 9.4 The periodic acid-Schiff stain after diastase digestion to remove glycogen demonstrates the presence of lipofuscin and other cell debris in Kupffer cells in acute hepatocellular injury.

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Iron Iron is readily demonstrated with the Prussian blue stain, which is also useful in bringing out the green color of bile and the golden brown color of lipofuscin, both of which can be masked by overstaining with either eosin or hematoxylin (Fig. 9.6). Copper is specifically best demonstrated by the rhodanine stain (Fig. 9.7), but the orcein and Victoria blue stains, which are technically easier, can also be used because these will stain concentrated deposits of the copper-binding protein, metallothionine. In the past, orcein and Victoria blue were primarily used to demonstrate the ground-glass inclusions of chronic hepatitis B infections (Fig. 9.8), but these have now been largely supplanted by specific immunostains, as discussed later.

▪ Figure 9.5 Globules of α 1 -antitrypsin are strongly periodic acidSchiff positive and diastase resistant.

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▪ Figure 9.6 The Prussian blue stain for iron demonstrates hemosiderin (blue granules) and also brings out the green color of bile and the golden brown color of lipofuscin.

P.249 Other stains that find occasional use include the Hall's stain for bile; the Fontana's stain for lipofuscin and Dubin-Johnson pigment; the phosphotungstic acid–hematoxylin stain for fibrin or mitochondria; the Congo red, sirius red, or crystal violet stains for amyloid; an acid-fast stain for mycobacteria, schistosome eggs, or the hooklets in the scolices of echinococcal cysts; and the Warthin-Starry stain for spirochetes, leptospira, or the bacilli causing catscratch disease. A Giemsa stain can be useful in studying the morphology of hematopoietic cells or in identifying some microorganisms, such as Leishmania or Cryptosporidia.

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▪ Figure 9.7 The rhodanine stain demonstrates copper as brick-red granules in liver cells in this case of Wilson disease.

Fat Fat can be demonstrated histochemically, but this requires unprocessed frozen sections, which must be prepared with a cryostat from fresh or formalin-fixed P.250 tissue. Routine processing exposes the tissue to organic solvents, which will extract lipids and render fat stains useless. However, frozen sections prepared and stained with oil red-O (Fig. 9.9) can be quite useful for demonstrating neutral lipid in liver cells in a variety of conditions or in cells of benign or malignant tumors. This stain may also be used to demonstrate fat globules of stellate cells, cholesterol crystals (which are also birefringent when examined under polarized light), and lipofuscin in liver or Kupffer cells. Cholesterol can be specifically stained in frozen sections by the Schultz modification of the Liebermann-Burchard reaction, a reaction useful for the diagnosis of Wolman's disease or cholesteryl ester storage disease. Metachromatic granules in macrophage cells and bile duct epithelium in metachromatic leukodystrophy are best demonstrated in frozen sections by using stains such as cresyl violet or toluidine blue.

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▪ Figure 9.8 The Victoria blue stain shows cells containing large amounts of hepatitis B surface antigen in a chronic carrier.

▪ Figure 9.9 Oil red O stain of a frozen section shows microvesicular fat in acute fatty liver of pregnancy.

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Immunopathology Immunostains are now routinely utilized in the diagnosis of hepatic neoplasms, but it has fewer practical applications in the study of nonneoplastic diseases of the liver. Nevertheless, these techniques can be

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used to demonstrate and characterize normal structural components and a number of histopathologic changes; they can also be used to locate viral antigens and other infectious agents. In the normal liver, bile duct epithelial cells react with monoclonal antibodies to cytokeratins 7, 8, 18, and 19 (Fig. 9.10), whereas the liver cells react only with monoclonal antibodies to cytokeratins 8 and 18 (2). Bile canaliculi are demonstrated by polyclonal antibodies to carcinoembryonic antigen (CEA) (Fig. 9.11) because of the presence of a cross-reacting biliary glycoprotein. Tumors derived from hepatocytes and bile ducts often maintain the antigenic characteristics of their normal counterparts, but this is not invariable, hence staining patterns must be interpreted in the context of other histologic features. A few practical applications for immunohistochemistry have been found in the diagnosis of non-neoplastic diseases. In chronic cholestatic disorders, such as PBC, cytokeratin type 7, normally only found in biliary-type cells, appears in periportal hepatocytes (3). Because cytokeratin proteins are a major component of Mallory bodies, antibodies to several high- and low-molecular-weight keratins may be used to demonstrate this pathologic feature, but none is as reliable for this purpose as staining with antibodies to ubiquitin (4), a cellular stress protein that coats the surface of filamentous tangles such as Mallory bodies (Fig. 9.12). Ubiquitin also coats tangles of amyloid filaments, but there are specific antibodies that can be used to confirm the diagnosis of amyloidosis and characterize the different types of amyloids (5).

▪ Figure 9.10 Immunostain with a cocktail of monoclonal antibodies that react with cytokeratin types 7, 8, 18, and 19. There is strongly positive staining of the bile duct in the center of the portal area and the ductular cells at the edge, whereas hepatocytes

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stain only weakly.

Immunostaining for viral antigens in different types of viral hepatitis is extensively used for investigational purposes and, to a lesser extent, for diagnosis. In routine practice, hepatitis B antigens (surface and core) are readily identified with commercially available antisera (Fig. 9.13). Hepatitis D can also be identified in routinely processed tissue, but antibodies are more difficult to obtain. Hepatitis A, C, and E can only be reliably identified in frozen sections, and staining for these is generally limited to research settings. Several viruses, other than those causing viral hepatitis, including herpes simplex virus, Cytomegalovirus (CMV), and adenovirus, can be detected in the liver by using commercially available antisera.

Electron Microscopy Transmission electron microscopy has many investigational but a limited number of diagnostic applications (6). Its greatest value is in the interpretation of biopsy specimens from patients with known or suspected metabolic disorders, and it can also be helpful in druginduced and cholestatic diseases and in some infections. Among the metabolic diseases, distinctive or pathognomonic ultrastructural findings are present in hereditary fructose intolerance, α 1 -antitrypsin P.252 deficiency, Farber's disease, glycogenoses types II and IV, Gaucher's disease, metachromatic leukodystrophy, Dubin-Johnson syndrome, erythropoietic protoporphyria, Wilson disease, Zellweger syndrome, and many others. Drug-induced injury causes changes in many organelles of the liver depending on the drug, duration of use, and other factors. Many drugs (e.g., phenytoin, phenobarbital) and toxins (e.g., DDT [2,2bis(p-chlorophenyl)-1,1,1,-trichloroethane] and other pesticides) cause proliferation of the smooth endoplasmic reticulum of liver cells (“induced” hepatocytes), which results in a characteristic ground-glass appearance on light microscopy. Megamitochondria, sometimes assuming monstrous forms, are considered typical of drug reactions, while lysosomal phospholipidosis is highly typical of several drugs (e.g., amiodarone). Subtle manifestations of cholestasis due to a variety of causes can be seen ultrastructurally before becoming recognizable by light microscopy. Among infectious agents, viral particles can be visualized directly in herpes simplex, adenovirus, and CMV infections, and both incomplete and complete particles of hepatitis B can be seen in infected liver cells.

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▪ Figure 9.11 Immunostain with polyclonal antibodies to carcinoembryonic antigen demonstrates dark-staining bile canaliculi between hepatocytes.

Scanning electron microscopy has also proved more useful for investigation than for diagnosis. The diagnostic applications of this technique are largely limited to particulate material, especially when xray spectrophotometry (also called electron probe analysis) is combined with scanning electron microscopy (7). Using this technique, the elements that are present in particulate material, such as talc, Thorotrast, silicone, silica, titanium, gold, and barium sulfate can be positively identified.

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▪ Figure 9.12 Immunostain with antibody to ubiquitin demonstrates dark-staining Mallory bodies (arrows) in liver cells in alcoholic hepatitis.

Other Special Techniques In situ hybridization is used to detect genomic deoxyribonucleic acid (DNA) of the hepatitis B virus (HBV) (8), and there are reports of the use of in situ hybridization and in situ polymerase chain reaction (PCR) to demonstrate the presence of hepatitis C virus (9), but currently, these are essentially research techniques. Polarizing microscopy is useful in identifying birefringent crystals of talc (Fig. 9.14) in portal macrophages or Kupffer cells in abusers of intravenous drugs (10). The remnants of previous surgery, such as suture material, talc, or starch from glove powder left on the surface of the liver are also birefringent in polarized light, as is silica in multiorgan silicosis (11). Type I collagen has a silvery birefringence, and amyloid has a characteristic apple green birefringence when sections stained with Congo red are examined by polarizing microscopy. Formalin pigment (typically in P.253 blood vessels) and both malarial and schistosomal pigments (in

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reticuloendothelial cells) are brown to black deposits of acid hematin and are birefringent under polarized light. Cholesterol crystals (e.g., in the livers of patients with Wolman's disease and cholesteryl ester storage disease) in frozen sections, whether stained or unstained, are birefringent, as are cystine crystals in cystinosis. Needle-like uroporphyrin crystals in liver cells can sometimes be visualized by polarizing microscopy of unstained frozen or paraffin sections in porphyria cutanea tarda (12). Red birefringent Maltese crosses and amorphous materials are characteristic of protoporphyrin accumulation in canaliculi or Kupffer cells in erythropoietic protoporphyria (Fig. 9.15) (13).

▪ Figure 9.13 Immunostains for hepatitis B antigens. Antibody to HBsAg (top) shows variable amounts of the antigen in the cytoplasm of some hepatocytes. Antibody to HBcAg (bottom) shows the antigen in nuclei of liver cells with replicative virus.

Ultraviolet (UV) microscopy is most useful in confirming the diagnosis in the hepatic porphyrias. However, unfixed, air-dried frozen sections are required, so the usefulness of the technique is limited. Nevertheless,

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frozen sections of the liver in porphyria cutanea tarda and erythropoietic protophorphyria reveal red autofluorescence under UV microscopy because of the presence of porphyrins. Vitamin A stored in stellate cells has a green and rapidly fading autofluorescence in UV light, while a granular yellow autofluorescence is characteristic of lipofuscin.

▪ Figure 9.14 Portal macrophages in the center of field (top) contain talc crystals, which are birefringent and easily visualized with polarizing microscopy (bottom).

Morphologic Patterns of Injury Acute Necroinflammatory Disease (Acute Hepatitis) Acute necroinflammatory disease is typically seen in case of acute infections with the hepatitis viruses, but identical injury may occur with hepatitis-like reactions to a number of therapeutic drugs (see Chapter 33). Hepatocellular injury, leading to cell death, is the predominant morphologic feature of acute necroinflammatory diseases, although the term necroinflammatory has become something of a misnomer in view of recent advances in pathobiology. The term necrosis, previously used for all forms of cell death, is now applied more selectively to certain

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forms of cell death. Many of the injured and dying cells seen in the various forms of hepatitis are actually in the process of apoptosis, while the “inflammatory” component is at times the effector of P.254 apoptosis and at times the response to the hepatocellular injury. Nevertheless, for the purposes of this discussion, the term necroinflammatory will be maintained.

▪ Figure 9.15 Deposits of protoporphyrin are birefringent and appear red in polarized light. Larger deposits show a characteristic Maltese cross.

Several basic lesions are seen in various forms of necroinflammatory injury: 1. Apoptosis (14, 15) results in the shrinkage of the hepatocyte, which often has an angular configuration and is more eosinophilic than its neighbors in the liver plate (“acidophilic degeneration”) (Fig. 9.16). The nucleus is often pyknotic and deeply basophilic. The cytoplasm of the liver cell develops protuberances that separate and are released into spaces of Disse and sinusoids. The larger cell fragments, which may contain parts of the nucleus, have been termed apoptotic, acidophilic, or hyaline bodies (Figs. 9.17 and 9.18). The apoptotic bodies are quickly phagocytosed by Kupffer cells or adjoining liver cells, where they undergo degeneration and are reduced to residual bodies. 2. Ballooning degeneration refers to the swelling of hepatocytes, often to several times the normal size. Affected cells have an indistinct cell membrane, and the cytoplasm is rarefied (Figs. 9.18

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and 9.19). The ballooned hepatocytes eventually undergo lysis, with disappearance or “dropping out.” The remnants of these cells attract lymphocytes and, less often, other types of inflammatory cells (“focal necrosis”), as well as hypertrophied Kupffer cells. 3. Coagulative necrosis refers to a form of cell death recognized by deeply eosinophilic, granular cytoplasm with loss of the nucleus and discohesion from the surrounding cells of the tissue (Fig. 9.20). The cell outline may be maintained for some time, but this is eventually lost as the tissue becomes amorphous. This change is typical of anoxic injury, although it may be seen in some forms of necroinflammatory injury. 4. Regeneration, recognized by enlargement of nuclei and nucleoli, mitoses, binucleation, and thickening of liver cell plates (Fig. 9.21), may be seen shortly after the onset of a necroinflammatory injury such as viral hepatitis. The number of regenerating cells gradually increases as the patient recovers. 5. Kupffer cell hypertrophy is characteristic of acute necroinflammatory injuries. Sinusoidal macrophages are normally inconspicuous, but in response to liver cell death, these enlarge as they perform their phagocytic function, and they can be recognized by the presence of cytoplasmic light brown, finely granular lipofuscin presumed to be phagocytosed from necrotic hepatocytes (Figs. 9.21 and 9.22).

Acute necroinflammatory patterns “Classic” acute hepatitis, typical of the common forms of acute viral hepatitis is characterized by panacinar necroinflammatory disease with spotty necrosis. The appearance of the liver is one of acinar disarray (Fig. 9.23) caused by widespread degeneration and death of individual and small groups of hepatocytes, which display features of both apoptosis and ballooning with focal necrosis. These are seen throughout the acinus in various combinations, and not all hepatocytes in a given acinus P.255 P.256 P.257 are affected. Features of regeneration are invariably present, and there is typically an inflammatory response consisting of hypertrophied Kupffer cells and lymphocytes. The portal areas in typical acute hepatitis are usually infiltrated with inflammatory cells. Lymphocytes predominate, but a small number of plasma cells, as well as eosinophils and neutrophils (especially in drug-induced disease), may be present. Occasionally, plasma cells predominate, especially in hepatitis A (16,17). The inflammatory response often extends beyond the confines

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of the portal areas, leading to some blurring of the outline of the limiting plate and creating the appearance of interface hepatitis, as discussed later under chronic hepatitis. This also is especially true in hepatitis A (Fig. 9.24). Cholestasis is not a significant component of the histopathology of “classic” acute viral hepatitis, and when present, it is usually seen as an occasional, haphazardly distributed canalicular bile plug. Occasional cases may reveal abnormalities of the bile ductal epithelium, including swelling, disruption, and infiltration by lymphocytes, which constitute the hepatitis-associated bile duct lesions that are discussed in the section on chronic hepatitis.

▪ Figure 9.16 Hepatocytes undergoing apoptosis (arrows) become shrunken, angulated and darker than their neighbors (arrow, center of field), lose their nuclei and begin to fragment, forming acidophilic bodies.

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▪ Figure 9.17 High magnification of an acidophilic body that has been extruded from the liver cell plate into a sinusoid. Most of the degenerated nucleus of the dead hepatocyte remains.

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▪ Figure 9.18 Cellular degeneration and death with apoptotic bodies (arrows), and ballooning (B).

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▪ Figure 9.19 Ballooning degeneration. The hepatocytes are swollen and pale. A cluster of inflammatory cells (“focal necrosis”) in the center of the field shows the position where a hepatocyte has disappeared from the tissue.

▪ Figure 9.20 Coagulative necrosis in a case of ischemic injury. The cytoplasm of the necrotic cells is eosinophilic and granular, and the nuclei have disappeared.

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▪ Figure 9.21 Active necroinflammatory injury with regenerating liver cells, recognizable by enlarged nuclei, prominent nucleoli, and binucleate liver cells (arrows). Clusters of hypertrophied Kupffer cells (K) are present at sites of liver cell dropout.

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▪ Figure 9.22 The periodic acid-Schiff stain after diastase digestion demonstrates clusters of hypertrophied, lipofuscin-filled Kupffer cells (dark-staining) at the sites of liver cell dropout.

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▪ Figure 9.23 Acute viral hepatitis. Note acinar disarray, apoptosis, and focal necrosis, Kupffer cell hypertrophy, and lymphocytic infiltrate.

The subsiding phase of viral hepatitis is characterized by a lessening of the injury and inflammation with increased regeneration and repair. The differences between this and the active phase are, however, mainly quantitative. Acinar disarray diminishes and eventually disappears, and the hepatic parenchyma gradually reverts to a normal appearance over a period of several weeks to months, although varying degrees of unrest are still evident. The liver cell plates often appear thickened. Only occasional degenerating cells and small foci of inflammation are evident. A frequent finding is the continuing hypertrophy of Kupffer cells and portal macrophages (Fig. 9.22). They become relatively more conspicuous because the hepatocytes are less swollen, and they now contain variable amounts of hemosiderin in addition to lipofuscin. The portal area inflammatory response gradually diminishes. Uncomplicated viral hepatitis is not followed by any significant periportal or intraacinar fibrosis.

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▪ Figure 9.24 Acute hepatitis A, showing marked portal inflammation with extension into the adjacent parenchyma (interface hepatitis), mimicking the appearance of chronic hepatitis.

Mononucleosis hepatitis is typical of Epstein-Barr virus (EBV) and CMV infections in immunocompetant patients (18,19,20). Similar histology can be seen in reactions to some drugs, especially diphenylhydantoin (21), and we have also observed this reaction on occasion in acute hepatitis B or C, so a complete serologic workup is advisable whenever this pattern of injury is seen. In comparison with “classic” viral hepatitis, the inflammatory response in this variant is more prominent (Fig. 9.25) while the hepatocellular injury is milder. Hepatocellular regeneration is prominent, and mitotic figures are often seen in hepatocytes, Kupffer cells, and P.258 portal mononuclear cells. Apoptosis is present but ballooning is absent or minimal. Kupffer cells are often markedly hypertrophied and sometimes form tiny granulomatoid foci or, rarely, true granulomas. The hepatic sinusoids characteristically contain an increased number of lymphocytes, sometimes closely packed together in a “string of beads” pattern (Fig. 9.25). In CMV infection, cytomegaly and viral inclusions are never seen in immunocompetent patients, but in CMV infections of

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the newborn, and of adults who are immunocompromised, characteristic intranuclear and cytoplasmic inclusions (Fig. 9.26) may be present in the bile duct and liver cells.

▪ Figure 9.25 Infectious mononucleosis hepatitis. There is a prominent sinusoidal mononuclear cell infiltrate along with the hepatocellular injury of an acute hepatitis.

Cholestatic hepatitis, that is, combined hepatocellular and cholestatic injury, is an uncommon complication of most types of acute viral hepatitis, but it is frequent in hepatitis E infection (22). As a pattern of injury, it is more frequently seen in reactions to a number of drugs (23). Synonyms for cholestatic viral hepatitis include “cholangiolitic” or “pericholangitic” viral hepatitis, while drug-induced injury is termed hepatocanalicular or mixed hepatocellular and cholestatic. The clinical and laboratory findings tend to simulate those of obstructive biliary tract disease. The histopathology of cholestatic hepatitis includes hepatocellular and canalicular bile stasis, often with pseudogland formation, and variable degrees of parenchymal injury (Fig. 9.27). There may be periportal ductular proliferation with infiltration by neutrophils (acute cholangiolitis), as well as many neutrophils in the portal inflammatory infiltrate, but the acinar bile ducts are not involved.

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▪ Figure 9.26 Cytomegalovirus infection in an immunodeficient host. The large cell in the center of the field has a characteristic intranuclear inclusion and many small cytoplasmic inclusions.

Neonatal giant cell hepatitis typically has features of acute hepatitis with transformation of hepatocytes into multinucleate giant cells. Newborns with this disease typically present with jaundice, and the principal differential diagnosis is between this and extrahepatic biliary atresia (see Chapter 47). The term idiopathic neonatal hepatitis is used for most cases in which no cause is found, but the features seen in some neonates with α 1 -antitrypsin deficiency may be identical to those seen in a number of other metabolic disorders and infections. The “idiopathic” cases are presumably secondary to undiagnosed viruses because most patients recover without sequellae. Histologically, all the features of acute hepatitis are present, along with significant bile stasis, but the most striking feature is giant cell transformation of hepatocytes (Fig. 9.28). The giant cells appear to result from the fusion of several liver cells to form a syncytium, and there may be up to several dozen nuclei in a single cell. The cholestasis may be quite prominent and there is often extramedullary hematopoiesis. Portal fibrosis and ductular proliferation, typical of biliary atresia, are not seen. Hepatocellular injury with giant P.259

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cell transformation also occurs in neonatal hemochromatosis, along with massive iron overload.

▪ Figure 9.27 Acute cholestatic hepatitis (combined hepatocellular–cholestatic injury). There is prominent cholestasis, as well as hepatocellular injury, acidophilic bodies, liver cell dropout, and inflammation.

Acute injury with microabscess formation is typical of a number of bacterial infections complicated by sepsis or hematogenous dissemination. This includes diseases caused by both gram-positive and gram-negative organisms, such as listeriosis (Fig. 9.29), melioidosis, and typhoid fever, as well as disseminated mycotic infections such as those caused by Cryptococcus, Candida, or Aspergillus species. Organisms may or may not be P.260 demonstrable in the lesions. In the immunocompromised host, CMV infection can also lead to this type of tissue response (with or without viral inclusions) in the liver. In all these diseases, lesions typically consist of varying-sized microabscesses, but they sometimes have a granulomatoid appearance. In CMV infection, the lesions are quite small, often only a single degenerating hepatocyte surrounded by neutrophils (sometimes containing an intranuclear inclusion), whereas bacterial and fungal infections may have grossly visible abscesses. In the later stages, lesions may have a purulent center and an organized granulomatous periphery, with variable fibrosis, especially in diseases such as meliodosis or typhoid.

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▪ Figure 9.28 Idiopathic neonatal hepatitis with giant cell transformation. Note the enlarged hepatocytes containing numerous nuclei.

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▪ Figure 9.29 Listeriosis. A microabscess is present in the center of the field because of hematogenous dissemination of the infection.

Not all focal necrosis with a neutrophilic response or microabscess formation is infectious. Focal necrosis with an outpouring of neutrophils is also the characteristic reaction to degenerating liver cells harboring Mallory bodies in steatohepatitis, alcoholic or nonalcoholic. Perivenular focal necrosis with neutrophilic aggregation is an iatrogenic artifact often observed in open surgical biopsy specimens of the liver. Acute injury with focal coagulative necrosis is seen in some viral infections in children, for example, coxsackie B4 and B9, but more importantly, this type of injury is typical of hepatic involvement in many types of viral hemorrhagic fevers, including yellow fever (Fig. 9.30), dengue, Lassa fever, and others (24). Haphazardly distributed single liver cells or clusters of liver cells are affected by coagulation necrosis, often with little or no inflammatory response. Viral inclusions are not present in any of these diseases.

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▪ Figure 9.30 Yellow fever. Many individual hepatocytes display coagulative necrosis in a haphazard distribution.

Acute injury with patchy or confluent coagulative necrosis is seen in disseminated herpes simplex hepatitis, whether occurring in neonates, children, or adults (25), both immunocompetent and immunocompromised. Similar findings are rarely seen in adenovirus hepatitis in immunocompromised patients (26). Viral inclusions are most easily identified in the relatively preserved hepatocytes at the margins of the necrotic foci. In herpes simplex, the classical Cowdry type A inclusions are eosinophilic, rounded or irregular, and surrounded by a clear halo with margination of the chromatin (Fig. 9.31). Adenovirus inclusions are more pleomorphic. Some resemble the Cowdry type A inclusions of herpes simplex but many are more basophilic and irregular in contour. Acute injury with zonal submassive or massive coagulative necrosis is typical of toxic injury from a number of direct hepatotoxins, although it may also be produced by ischemic injury. Among toxins, acetaminophen overdose is by far the most frequent cause of this type of injury (27). The tissue maintains its acinar architecture, but hepatocytes in zone 3 are entirely necrotic (Fig. 9.32), with progressive involvement of zones 2 and 1 with increasing severity of injury. In the most severe cases, only a thin rim of viable hepatocytes surrounds each portal area. Acute hepatitis with submassive necrosis and stromal collapse can be seen with severe hepatitis of any cause. This pattern of injury is more frequently encountered in biopsy and with surgical material from patients having drug-induced liver disease than in viral hepatitis, partly because patients with acute viral hepatitis are rarely subjected to

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biopsy and because drug-induced injury tends, on average, to be more severe than viral P.261 hepatitis, and also because many drugs are preferentially metabolized by hepatocytes of zone 3, thereby having the greatest toxic effects in this part of the acinus. There are patients who have not been exposed to a drug or chemical but develop fulminant liver failure with submassive or massive hepatic necrosis and in whom no evidence for any of the known hepatitis viruses can be found serologically or by PCR for viral DNA or ribonucleic acid (RNA) (27,28). These may be caused by some as yet undiscovered viral agent, but for now they remain enigmatic and unclassified. Finally, autoimmune hepatitis, although considered a chronic disease, often has an acute clinical presentation, and biopsies from the patients with this type of hepatitis may also show an appearance of acute hepatitis with submassive necrosis (29).

▪ Figure 9.31 Herpes simplex hepatitis. Several of the nuclei have eosinophilic Cowdry type A inclusions surrounded by a clear halo with margination of the chromatin (arrows).

Submassive necrosis of any cause is due to the simultaneous death of the hepatocytes of an entire zone or more of the hepatic acini, thereby producing confluent necrosis, lysis of the necrotic tissue, and collapse of the supporting stroma. The necrosis usually involves zone 3 and, less often, zone 2 of the hepatic acini (Fig. 9.33), but viral hepatitis A and

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injury due to some drugs and toxins are characterized by necrosis predominantly involving zone 1 (Fig. 9.34). In various planes of the section, acinar zone 3 necrosis may appear to be entirely around the terminal hepatic venule (“centrilobular”), may appear to extend between the terminal venules of adjacent acini, or may extend from the terminal venule to the edge of the portal area. Consequently, when necrosis affects zone 3, the collapsed reticulin framework may extend between adjacent vascular structures, making them appear linked together (“bridging necrosis”), and there may be linkage of portal areas with terminal hepatic venules (“portal–central bridging”) or of two or more terminal hepatic venules (“central–central bridging”), both due to submassive zone 3 necrosis. Acute hepatitis with massive necrosis, the most extreme form of acute hepatocellular injury, may be caused by viral hepatitis or drug-induced liver disease. There is virtually complete loss of hepatocytes (Fig. 9.35), but occasionally, the haphazardly distributed cells can survive, as can a cuff of cells around portal areas. The reticulin framework is usually intact but frequently collapsed because of loss of liver cells, with resultant approximation of portal areas. Variable numbers of inflammatory cells are present in the areas of collapse. These include lymphocytes and plasma cells, as well as a lesser number of eosinophils and neutrophils. Central vein endophlebitis may be present. The collapsed parenchyma contains numerous hypertrophied Kupffer cells with cytoplasm packed with lipofuscin. Zone 1 of the hepatic acinus typically shows proliferation of the putative hepatic stem cells (Fig. 9.36), forming ductules and ductular hepatocytes (30).

Chronic Necroinflammatory Injury (Chronic Hepatitis) Chronic necroinflammatory disease refers to a morphologic pattern that is seen most often not only in chronic viral hepatitis but also in autoimmune hepatitis, occasional drug reactions, and, in rare instances, some metabolic diseases. As in acute necroinflammatory disease, there is hepatocellular injury and inflammation, but in the chronic diseases, the brunt of the injury tends to be portal and periportal rather than panacinar, and the injury is accompanied by fibrosis that can progress to cirrhosis. Chronic hepatitis, regardless of cause, is characterized by several pathologic changes that are present to a variable extent in each case. These include portal inflammation and sometimes lesions of bile ducts within the portal spaces; periportal injury and inflammation; several forms of degeneration and death by apoptosis of intra-acinar hepatocytes with an associated inflammatory response; and fibrosis that may involve only the portal and periportal areas or that may form septa.

Morphology of chronic hepatitis

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Portal inflammation—in all forms of chronic hepatitis the portal areas are variably infiltrated by lymphocytes and plasma cells. Lymphoid aggregates or follicles with P.262 P.263 germinal centers may be present and are now considered typical, although not pathognomonic, of chronic hepatitis C (Fig. 9.37). Immunohistochemical studies have shown that even when germinal centers are not apparent by light microscopy, these are true functional lymphoid follicles (31). The germinal centers contain activated B cells surrounded by a follicular dendritic cell network and a mantle zone of B cells, which, in turn, is surrounded by a T-cell zone. Patients with autoimmune hepatitis will often P.264 have large numbers or plasma cells in the portal inflammatory infiltrate (Fig. 9.38). Biopsy specimens from patients who are affected by chronic hepatitis through intravenous drug abuse may have birefringent talc crystals in portal macrophages (Fig. 9.14) (10).

▪ Figure 9.32 Submassive zonal coagulative necrosis in a fatal case of acetaminophen overdose. The necrotic hepatocytes of zones 2 and 3 are present in the section, while some of the zone 1 (periportal) cells survive.

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▪ Figure 9.33 Acute submassive necrosis of acinar zones 3 and 2. Surviving liver cells are predominantly periportal in zone 1 of the acini. In contrast to the coagulative necrosis shown in Figure 9.32, there is a collapse of the stroma where the hepatocytes have been lost.

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▪ Figure 9.34 Acute submassive necrosis of zone 1. With the Prussian blue stain, hemosiderin-laden macrophages (darkstaining) are shown to outline the areas of periportal necrosis and liver cell loss.

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▪ Figure 9.35 Acute hepatitis with massive hepatic necrosis. There is loss of all hepatocytes with proliferation of ductules in the collapsed hepatic stroma.

▪ Figure 9.36 Ductular proliferation in massive hepatic necrosis.

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The putative stem cells of the liver have proliferated, forming ductules and differentiating into hepatocytes in a vain attempt to repopulate the liver. The left panel has a portal area with an acinar bile duct (D) surrounded by collapsed stroma that contains proliferating ductules and inflammatory cells. The right panel shows ductules at high magnification. Some of the ductular cells have granular, eosinophilic cytoplasm, indicating differentiation into hepatocytes.

▪ Figure 9.37 Chronic portal inflammation with a lymphoid aggregate that has a germinal center in a patient with chronic hepatitis C.

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▪ Figure 9.38 Autoimmune hepatitis with large number of portal plasma cells, recognizable by their eccentric nuclei and clear perinuclear Golgi zone.

Hepatitis-associated bile duct lesions were first described in chronic hepatitis (32), but lesions may also be found in biopsy specimens of acute hepatitis. The lesion is characterized by swelling, vacuolization, nuclear irregularity, and sometimes, pseudostratification of the biliary epithelial cells (Fig. 9.39). The basement membrane may appear to be ruptured, and lymphocytes, occasional plasma cells, and sometimes, neutrophils infiltrate the duct. The lesion is reminiscent of and sometimes indistinguishable from the “florid duct lesions” of PBC. However, in contrast to the lesions of PBC, the ducts are not destroyed, and so portal areas without ducts are seldom seen and features of chronic cholestasis do not develop. Serial section reconstruction studies (33) have demonstrated that the most frequently observed lesions are actually blind diverticula arising from injured ducts rather than the ducts themselves. The ductal lesions have been seen in all forms of hepatitis, but most commonly in hepatitis C (34). Interface hepatitis is now the preferred term for the lesion formerly known as piecemeal necrosis (35). The original term was defined by an international group as “the destruction of liver cells at an interface between parenchyma and connective tissue, together with a

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predominantly lymphocytic or plasma cell infiltrate” (36). It is now apparent that the destruction of liver cells is primarily through apoptosis, and because the dead hepatocytes quickly disappear from the tissue, it is the location of the inflammatory component that permits recognition of the lesion, making interface hepatitis the more accurate term. Interface hepatitis has long been considered to be a key lesion in the progression and pathogenesis of chronic hepatitis, and the degree of periportal injury (mild, moderate, or marked) is still used to grade the degree of activity. Interface hepatitis can be most easily recognized as irregularity of the limiting plate, caused by extension of the portal inflammation through the plate into the periportal parenchyma (Fig. 9.40). The limiting plate becomes irregular and may disappear as the portal area expands. Inflammatory cells surround and invade injured hepatocytes (“emperipolesis”). There may be evidence of hepatocellular degeneration and death, characterized by either acidophilic or ballooning degeneration. As in acute hepatitis, cell death occurs principally by the process of apoptosis, resulting in the formation of apoptotic or acidophilic bodies, which rapidly disappear from the liver P.265 plates or sinusoids. As chronic hepatitis progresses, there is continuous erosion of the hepatic parenchyma, with closer and closer approximation of expanded portal areas, and small groups of hepatocytes (“hepatocytic islets”) become trapped in expanded portal zones. The necroinflammatory changes are gradually succeeded by fibrosis, often best appreciated with a Masson or other collagen stain. Delicate collagen fibers laid down in areas of periportal liver cell loss eventually condense into scars. Interface hepatitis may not involve all the portal areas equally in a given biopsy specimen. It may affect either a segment or the entire perimeter of a portal area. Furthermore, even after cirrhosis has developed, interface hepatitis can continue unabated along the fibrous septa, causing further loss of parenchyma and, eventually, clinical decompensation of the cirrhosis.

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▪ Figure 9.39 Hepatitis-associated bile duct lesion with marked epithelial injury and infiltration by chronic inflammatory cells, similar to the florid duct lesions of primary biliary cirrhosis.

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▪ Figure 9.40 Interface hepatitis (“piecemeal necrosis”) can be most easily recognized as irregularity of the limiting plate, caused by extension of portal inflammation through the plate into the periportal parenchyma.

Parenchymal injury, causing intra-acinar necroinflammatory changes, is present to some degree in most biopsy specimens from patients with any type of chronic hepatitis. This is typically multifocal (“spotty”) in distribution and consists mainly of apoptosis, as in acute hepatitis. Scattered apoptotic bodies of varied size are observed, as well as focal aggregates of lymphocytes, plasma cells, and hypertrophied Kupffer cells that have scavenged the apoptotic bodies and other debris, producing lesions traditionally called focal or spotty necrosis. More severe intra-acinar injury is generally seen when the biopsy is performed during an acute exacerbation of the chronic hepatitis, even if the patient is asymptomatic. Changes typical of acute hepatitis, superimposed on those of chronic hepatitis, may include an increase in the degree of spotty necrosis; ballooning degeneration, often most severe in zone 3, with dropout of hepatocytes and central–central or central–portal bridging necrosis, especially in autoimmune hepatitis; variable cholestasis, often with associated periportal ductular proliferation and infiltration of the ductules by neutrophils; or (in extreme cases) multiacinar necrosis with stromal collapse. There is

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simultaneous regeneration of hepatocytes as cells are lost through apoptosis. This is typically seen in the form of two-cell thick plates and an increased number of bi- and trinucleated hepatocytes, but mitotic figures may occasionally be present. There may be some degree of steatosis, generally macrovesicular and of mild to moderate severity, most often in hepatitis C but also in chronic hepatitis of other causes. Fibrosis is an almost invariable part of chronic hepatitis, although the degree of fibrous tissue deposition is quite variable from patient to patient. Fibrosis is the progressive component of the disease because it is the fibrous scarring that leads to architectural distortion and cirrhosis. It is thought that at least two pathways may lead to the fibrosis of chronic hepatitis. Probably most important in chronic viral hepatitis is the collagen deposition that accompanies the periportal injury of interface hepatitis, causing fibrous expansion of the portal tracts. As the disease progresses, portal–portal fibrous bridges are formed, filling zone 1 between adjacent acini. There may also be formation of “central–portal” and sometimes central–central fibrous bridges, which can develop from superimposed episodes of necrosis involving zone 3. In addition, it is likely that broad areas of fibrosis can result from the healing of bouts of multiacinar necrosis or from ischemic injury due to vascular damage secondary to the inflammation (see Chapter 7). In evaluating needle biopsies, it is important to distinguish tangential cuts through enlarged portal areas, which contain preexisting bile ducts and portal vessels, from true bridging fibrosis, which forms septa through parenchyma that had no preexisting fibrous tissue (Fig. 9.41). The scars of bridging fibrosis contain elastic fibers in addition to collagen. Like scars in any tissue, these tend to contract. Contraction of the fibrous septa in concert with nodular regeneration of the surviving parenchyma produces architectural distortion, and when complete nodules have formed, surrounded by fibrous septa, the result is the development of cirrhosis. Before the architecture is entirely obliterated, parts of the tissue are nodular while whereas adjacent areas maintain an acinar structure, a P.266 state that can be regarded as an “incomplete” cirrhosis. When necroinflammatory changes continue along the septa and within the nodules, this may be considered active cirrhosis, or a term such as chronic hepatitis with cirrhosis may be used.

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▪ Figure 9.41 Bridging fibrosis (B) is scar tissue that forms across an area of parenchyma that had no preexisting fibrous tissue. It must be distinguished from tangential cuts through fibrotic preexisting portal areas (P), which contain bile ducts and arteries.

There are several known causes of chronic hepatitis, and although the histopathologic features are similar, there are some noteworthy features that are more characteristic of one type than another. Parenterally transmitted forms of viral hepatitis, which account for at least 90% of cases, are discussed in detail in Chapters 29 and 30. Approximately 5% to 10% of chronic hepatitis is autoimmune (see Chapter 31). Drug-induced liver disease is a rare but well-documented cause of chronic hepatitis (23), and if the other known causes are excluded, this should always be considered and evaluated clinically with a complete drug history. Metabolic diseases, such as Wilson disease, α 1 antitrypsin deficiency, and hemochromatosis are sometimes listed in textbooks and reviews as causes of chronic hepatitis, but because these are usually readily distinguished from chronic hepatitis by liver biopsy and laboratory tests, they are considered separately in this chapter. Hepatitis B can be diagnosed histologically and distinguished from other causes of chronic hepatitis by demonstration of the virus in tissue. Hepatitis B surface antigen (HBsAg) can be demonstrated by histochemical stains (orcein or Victoria blue, Fig. 9.8) or the more sensitive immunostains (Fig. 9.13) in 80% or more cases of chronic

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hepatitis B. Cells containing large quantities of HBsAg have cytoplasm with a uniform finely granular appearance, the so-called ground-glass cells (Fig. 9.42), which are scattered randomly through the liver, often occurring in clusters. The number of ground-glass cells tends to be inversely related to the activity of the hepatitis. Most cells are found in livers with the least active disease, whereas livers with the most activity tend to have the fewest ground-glass cells. In acute hepatitis B, the immune response eliminates antigen-containing cells and immunostains are entirely negative. Conversely, the presence of stainable surface antigen proves a chronic rather than an acute infection, even when there is severe hepatocellular injury. Hepatitis B core antigen (HBcAg) can also usually be immunohistochemically demonstrated in nuclei, and sometimes cytoplasm when there is chronic disease. The presence of core antigen reflects active viral replication, and so the amount of core tends to be directly proportional to the activity of the hepatitis. Patients with recent acute exacerbations will have the most core and will often have HBcAg in hepatocyte cytoplasm and in numerous nuclei. Strains of virus with precore mutations associated with increased disease severity have also been found to have increased cytoplasmic core antigen (37). Hepatitis C virus cannot currently be reliably demonstrated in routinely processed liver biopsies. There P.267 are, however, histologic features that are characteristic, although not pathognomonic, of chronic hepatitis C (34), and the finding of these features should prompt a serologic evaluation if not already done. Chronic hepatitis C tends to have more intense chronic portal inflammation than other types of chronic hepatitis, often with lymphoid aggregates and sometimes follicles with germinal centers (Fig. 9.37). There is also a greater tendency toward hepatocellular fat accumulation than in other types. Approximately 50% of biopsy specimens have some fat, and in approximately 10% this may be considerable. Patients infected with genotype 3 tend to have even more fat, and it is suggested that this may be due to a cytopathic effect (38). Hepatitisassociated bile duct lesions (see preceding text) may be found in acute or chronic hepatitis of any cause, but they are most frequent in hepatitis C. Severe degrees of bile duct injury can be seen in approximately 10% to 15% of biopsy specimens from patients with chronic hepatitis C (Fig. 9.39). Lesser degrees of duct irregularity and lymphocytic infiltration can be found more often.

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▪ Figure 9.42 Ground-glass cells (arrows) in chronic hepatitis B. The cytoplasm of liver cells containing large quantities of hepatitis B surface antigen (HBsAg) has a uniform finely granular appearance.

Hepatitis D can only infect individuals who are also infected with HBV, which serves as an obligatory helper. Simultaneous coinfection with HBV and hepatitis delta virus (HDV) tends to cause more severe disease than HBV alone, with a higher likelihood of fulminant hepatitis. HDV superinfection of a person with previous chronic HBV infection often causes an acute exacerbation of the underlying chronic hepatitis or deterioration in the clinical status of a previously stable patient, or it may cause fulminant liver failure. Morphologically, HDV superimposed on HBV tends to produce more severe disease than hepatitis B alone, but there are no features that specifically implicate hepatitis D (39). The only way to histologically prove presence of the virus is to demonstrate delta antigen in the hepatocyte nuclei by immunohistochemical staining (although commercial antibodies are not widely available) or to detect antibodies to delta antigen in the blood. Autoimmune hepatitis tends to be a very severe chronic hepatitis, often with multiacinar collapse and/or cirrhosis at the time of presentation. Numerous plasma cells are often seen in the portal inflammatory infiltrate (Fig. 9.38). About one third of cases have an acute onset, and,

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typically, there is severe acute hepatitis-like hepatocellular injury, often with diffuse ballooning of hepatocytes, regeneration with hepatocyte rosette formation, and sometimes, confluent zone 3 hepatocellular necrosis (29). Extensive giant cell transformation (40) is seen in some cases, which have been called postinfantile giant cell hepatitis or syncytial giant cell hepatitis. Recurrent chronic hepatitis after liver transplantation may resemble the original disease or may have atypical features. Hepatitis B, before antiviral therapy became established as standard post-transplantation therapy, virtually always recurred and in many cases caused a severe, rapidly progressive disease in immunosuppressed patients. The term fibrosing cholestatic hepatitis was proposed for this form of hepatitis B (41). Liver biopsy specimens show numerous ground-glass hepatocytes with massive amounts of intracellular HBsAg and HBcAg, and it is thought that this represents a cytopathic form of viral infection, in contrast to the usual chronic hepatitis B. As the disease progresses, there is portal and diffuse pericellular fibrosis, hepatocyte dropout, and in the late stages, nodular regeneration, producing cirrhosis (Fig. 9.43). Cholestasis in the tissue may be severe, but the patients typically have elevated serum bilirubin concentration even when bile pigment is histologically inapparent, hence the “cholestatic” part of the name. Hepatitis C also recurs, but most patients have histologic features of typical chronic hepatitis. Occasionally, however, patients display features of fibrosing cholestatic hepatitis, except for ground-glass cells (42). It is not clear whether the pathogenesis is the same as that for hepatitis B. Both hepatitis B and C occasionally produce the pattern of fibrosing cholestatic hepatitis in patients who have not undergone liver transplantations but are immunosuppressed or immunodeficient for other reasons (43).

▪ Figure 9.43 Recurrent hepatitis B with fibrosing cholestatic

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hepatitis progressing to cirrhosis 1 year after liver transplantation. The surviving hepatocytes have abundant cytoplasmic hepatitis B surface antigen (HBsAg), producing a ground-glass appearance, and there is canalicular bile stasis.

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Grading and staging of chronic hepatitis The stage of any disease is a measure of how far it has progressed in its natural history, with the end stage resulting in death of the patient or failure of the organ. The grade of the disease is meant to reflect how quickly the disease is progressing to the end stage. In chronic hepatitis the end stage is cirrhosis with clinical decompensation, whereas earlier stages have lesser degrees of fibrosis or cirrhosis. The grade is considered to be the degree of inflammation and hepatocellular injury, which is thought to lead to fibrosis. The old terminology that classified chronic hepatitis as “chronic persistent hepatitis,” implying a benign, nonprogressive disease, or “chronic active hepatitis,” implying a disease with a high likelihood of progression to cirrhosis, was a form of grading, but advances in understanding the causes and elucidating the natural history of the diseases that produce this type of liver injury has rendered this terminology obsolete. There are several methods, currently in use, of expressing the grade and stage of chronic hepatitis. These can be grouped into those that are simple verbal descriptions, those that are relatively simple numeric grades and stages that correspond to the verbal descriptions, and those that use more complicated numeric scoring of histologic features to generate numbers that correspond to the grade and stage. Each method has advantages and disadvantages, and the system used should be appropriate to its suitability for the task at hand. In general, more complex systems have the capability to provide more information than simple ones but are less reproducible. For routine diagnosis and patient management a simple system of grading and staging is preferred, and we recommend the guidelines that were proposed by a panel of experts convened by the International Association for the Study of the Liver (IASL) in 1994 (44). Grading of chronic hepatitis is accomplished by deciding whether the degree of activity is mild, moderate, or marked. Although this seems rather simple, it is essentially subjective and not highly reproducible between pathologists or even by the same pathologist (45). The principal features used to determine grade are the degree of periportal interface hepatitis (“piecemeal necrosis”) and spotty parenchymal injury (Table

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9.1). We consider interface hepatitis to be mild when one must search for a foci in the biopsy specimen; moderate when most portal areas have some interface hepatitis, but it extends around less than 50% of the circumference in the majority; and marked when most portal areas have interface hepatitis extending around more than 50% of the circumference. Parenchymal injury is most easily graded using the 10× (medium power) objective of the microscope with the usual 10× ocular lens. At this magnification it is possible to detect acidophilic bodies, ballooned hepatocytes, and clusters of inflammatory cells at sites of focal necrosis, and it is relatively easy to estimate the amount of injury and form an overall impression of the degree of injury. We consider parenchymal injury to be mild when fewer than five injured cells or clusters P.269 of inflammatory cells are seen per 10× field, moderate when there are 5 to 20, and marked when there are more than 20 per 10× field. Portal inflammation can also be considered, but this is more a sign of chronicity than of activity. In grading the overall activity, the chronic hepatitis can be considered as being mild when both interface hepatitis and parenchymal injury are mild or absent, moderate if both interface hepatitis and parenchymal necrosis are moderate or if one is moderate but the other is mild, and marked if interface hepatitis and/or parenchymal injury is marked.

Table 9.1. Grading Activity in Chronic Hepatitis

Grade Mild

Interface hepatitis Found only after diligent

Parenchymal injury a 20 per 10×

Either

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circumference of most portal

field

areas

interface hepatitis or parenchymal injury is marked

a

Apoptotic bodies, ballooned cells, inflammatory cell

aggregates.

Staging of chronic hepatitis requires assessment of the degree of fibrosis, which requires a Masson trichrome stain for proper evaluation. There is progression in the stage of disease as fibrosis advances from none to fibrous portal expansion, bridging fibrosis, incomplete cirrhosis, and finally to established cirrhosis. Following the recommendations of the IASL panel (44), the diagnostic line of the pathology report should indicate the cause of the chronic hepatitis and, if known, the grade and the stage. Therefore, the report may read “chronic hepatitis C with mild activity and portal fibrosis”; or “chronic hepatitis B with moderate activity and extensive bridging fibrosis”; or “chronic autoimmune hepatitis with marked activity and established cirrhosis.” For those who prefer numbers to words, there are simple numeric scores that generally correspond to verbal diagnoses (Table 9.2), including the Batts-Ludwig (46) and Metavir (47) systems. We prefer the verbal diagnoses because these avoid the false sense of quantification that numbers tend to engender. Complex numeric systems have also been proposed for grading and staging chronic hepatitis, including the Knodell Histology Activity Index (48), commonly called the Knodell score, and its modified form, known as the Ishak score (35). For grading, these systems assign numbers to the severity of the necroinflammatory features (e.g., interface hepatitis, confluent necrosis, parenchymal injury, and portal inflammation) and add these numbers to arrive at a grade that can range from 0 to 18. The stage, ranging from 0 to 4, may or may not be added into the Knodell score; in the Ishak score, the stage, ranging from 0 to 6, is reported separately. Numeric scores generated by these systems are useful for investigational studies that involve large numbers of patients requiring statistical analysis. These scores are a good way of showing differences in histologic response between cohorts of patients receiving different forms of therapy, and they have been used successfully in many large clinical trials. However, studies have

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shown that there is fairly poor reproducibility for these scores when applied to individual liver biopsies, both between different pathologists and by the same pathologist at different times (45,49). When dealing with an individual liver biopsy, the pathologist should avoid complex numeric scores and concentrate on a meaningful verbal report. Follow-up biopsies from patients who are being treated for chronic hepatitis should be evaluated in the context of their previous biopsies. The biopsy is performed in this clinical setting to see whether the activity of the patient's liver disease has improved or whether there has been progression of fibrosis. The only meaningful evaluation is one that compares the initial biopsy with the follow-up biopsy. It is essential that this be done by a single pathologist (although the clinician may wish to look on) comparing both biopsies together. A comparison of pathology reports P.270 or numeric scores generated at different times can only lead to confusion and incorrect conclusions about the course of the patient's disease.

Table 9.2. Simple Numeric Grading and Staging SystemsT hat Correspond to Verbal Diagnoses

Metavir

Batts-Ludwig

Grade

(47)

(46)

Chronic hepatitis, minimal

A1

Grade 1

Chronic hepatitis, mild

A1

Grade 2

Chronic hepatitis, moderate

A2

Grade 3

Chronic hepatitis, marked

A3

Grade 4

No fibrosis

F0

Stage 0

Portal fibrosis

F1

Stage 1

Stage

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Few bridges

F2

Stage 2

Many bridges

F3

Stage 3

Cirrhosis

F4

Stage 4

Acute Cholestasis Cholestasis can be defined as the arrested flow of bile. Morphologically, when there is an acute impediment to bile flow, no matter the cause, bile pigment can usually be found in hepatocytes, canaliculi (Fig. 9.44), and sometimes Kupffer cells, predominantly in acinar zone 3 (“centrilobular”), except when hyperbilirubinemia is minimal. When jaundice is severe, especially in mechanical biliary obstruction, bile pigment may be seen in the lumina of ductules or acinar bile ducts (Fig. 9.45). Bile may be confused with other pigments, particularly hemosiderin and lipofuscin. It is typically a darker brown than the pale yellow lipofuscin. Lipofuscin is more granular and is more likely to be found near the cytoplasmic membrane. Hemosiderin is dark brown, glassy, and usually more refractile than bile or lipofuscin. The Prussian blue stain for iron is useful for identifying bile and so is Hall's stain for bilirubin. Many disorders, including alcoholic liver disease, drug-induced hepatotoxicity, viral hepatitis, and various developmental and metabolic diseases, can be associated with intrahepatic cholestasis. In general these show features typical of the basic pattern of injury, and cholestasis is a minor component of the picture. This section deals with cholestasis as the predominant feature.

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▪ Figure 9.44 Multiple bile plugs (arrows) in zone 3 canaliculi in a patient with an acute onset of cholestatic jaundice.

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▪ Figure 9.45 Bile in an acinar bile duct (arrow) in extrahepatic biliary obstruction.

“Bland” cholestasis and cholestatic hepatitis “Bland” cholestasis refers to an acute cholestatic injury unaccompanied by hepatocellular injury or bile duct injury. The cholestasis caused by some drugs, such as anabolic and contraceptive steroids, is typically “bland,” unaccompanied by hepatocellular injury of more than a minimal degree (50). The differential diagnosis, however, includes mechanical biliary obstruction because in the early stages, portal area changes, as noted in the subsequent text, may not be present. In some patients, the cause of the “bland” cholestasis is never found. Benign recurrent intrahepatic cholestasis (BRIC) is a term used for a familial disorder caused by mutations of the FIC1 gene that is also responsible for progressive familial intrahepatic cholestasis type 1 (PFIC-1) (51). BRIC is characterized by bouts of cholestasis that are self-limited and not followed by fibrosis or cirrhosis. Biopsy specimens show moderate to marked cholestasis and little or no hepatocellular injury. Similar findings P.271 are noted in the syndrome of recurrent jaundice of pregnancy (52). Cholestatic hepatitis, as noted in the preceding text, is a combined

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hepatocellular and cholestatic injury, which may be due to viral hepatitis but which is more often due to drug-induced liver disease (23,50). Acute bile stasis, along with spotty necrosis, hepatocellular ballooning, and/or apoptotic bodies, brings up this differential diagnosis.

Cholestasis with acute cholangitis Cholestasis with acute cholangitis is typical of mechanical (large duct) biliary obstruction of any cause, such as choledocholithiasis, neoplasms, strictures (e.g., neoplastic, inflammatory, or postoperative), sclerosing cholangitis, pancreatitis, choledochal cysts, pancreatic pseudocysts, biliary atresia, and several parasitic diseases (e.g., ascariasis, fascioliasis), or even extrinsic pressure from enlarged lymph nodes, tumors, or aneurysms. The key diagnostic feature is acute inflammation (i.e., neutrophils) with epithelial injury of the acinar bile ducts. Bile ducts are usually found adjacent to the corresponding small branches of the hepatic artery with approximately the same diameter. The ducts must be distinguished from ductules or cholangioles, as they have also been called. Reactive ductules (“ductular proliferation”) are found at the margins of portal tracts (Fig. 9.46) and should not be confused with bile ducts because changes affecting them do not have the same significance as identical changes in bile ducts (53,54). Ductules, which are usually more angulated than bile ducts, become prominent and appear to proliferate in response to a variety of injuries (55). Neutrophils are commonly situated in and around the reactive ductules, but this does not have the same significance as acute cholangitis, which is characterized by neutrophils in or around the acinar bile duct (Fig. 9.47) and is highly suggestive (but not pathognomonic) of mechanical biliary obstruction. Cholangitis may be present without histologic bile stasis, depending on the degree of obstruction; bile pigment is not usually found without complete obstruction, but acute cholangitis indicates a high likelihood of an obstruction being present. Bile pigment, when present, is seen first in acinar zone 3 and later in zones 2 and 1 as jaundice becomes more profound. Rarely, there is bile in the lumina or epithelium of the acinar bile ducts (Fig. 9.45), but when present, this strongly suggests the presence of obstruction. Other frequent findings include ductular reaction with associated acute inflammation, neutrophilic infiltration of the portal tracts, and bile duct epithelial irregularity or hyperplasia. Severe acute cholangitis is occasionally complicated by rupture, with the development of cholangitic abscesses in the region of the affected bile ducts (Fig. 9.48). Remnants of the disrupted biliary epithelium, bile, and mucin are often located within the abscesses. Xanthomatous cells and foreign body giant cells with phagocytosed bile may also be present. Bile lakes, due to extravasation of bile, and bile infarcts may be seen when there is duct rupture in advanced cases (Fig. 9.49).

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▪ Figure 9.46 Reactive ductules at the margin of an edematous, inflamed portal tract.

Although an acute cholangitis most often denotes extrahepatic biliary tract disease with an ascending infection, there are rare nonobstructive causes, P.272 including toxic shock syndrome, several toxins (e.g., paraquat, methylene diamine, and the toxin of toxic oil syndrome), and a number of drugs (e.g., chlorpromazine, allopurinol and amoxicillin–clavulanate) (56).

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▪ Figure 9.47 Acute suppurative cholangitis in a patient with mechanical biliary obstruction. The portal area is edematous and contains many neutrophils. Neutrophils are present in the lumina of two bile ducts (arrows).

Bile ductular cholestasis Neutrophils may also be associated with inspissated bile in dilated periportal ductules (Fig. 9.50), a lesion called bile ductular cholestasis (57). This lesion is sometimes seen in severely ill patients with sepsis and/or dehydration (57,58), but like other forms of ductular reaction, it does not necessarily indicate mechanical biliary obstruction.

Chronic Cholestasis Clinical and histologic features of chronic cholestasis appear when there is impaired flow of bile that persists for more than a few weeks. However, most chronic cholestatic disorders are insidious in onset, and chronic cholestasis progresses slowly over the course of years before it becomes clinically apparent. The most reliable histologic sign of chronic cholestasis is the lesion known as cholate stasis (53), which is also called pseudoxanthomatous change, xanthomatous change, or feathery degeneration. These terms refer to a foamy transformation of the cytoplasm of hepatocytes, Kupffer cells, and biliary epithelial cells,

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which is seen when there is any type of prolonged (chronic) cholestasis (Fig. 9.51). The affected cells are foamy and often bile stained, as a result of the accumulation of the bile salt and lipid components of bile. Other changes seen in chronic cholestasis include periportal bile pigment, copper accumulation demonstrated with special stains for copper (rhodanine) or by staining for the copper-binding protein, a metallothionein protein within lysosomes (Victoria blue stain) and, in some cases, periportal Mallory bodies. Although there are a number of causes of chronic cholestasis, the most frequent are PBC (see Chapter 24) and primary sclerosing cholangitis (see Chapter 23). Furthermore, in patients who have undergone liver transplantation, allograft rejection can produce bile duct damage and loss, leading to chronic cholestasis.

▪ Figure 9.48 Cholangitic abscess, secondary to ascending cholangitis. The two bile ducts at the bottom of the field are filled with neutrophils.

Primary biliary cirrhosis The diagnosis of PBC is usually made on the basis of a constellation of clinical, serologic, and histologic findings. In a patient known to have a positive antimitochondrial antibody (AMA) liver biopsy is usually P.273 performed to confirm the diagnosis and assess the stage of disease. In

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a patient who has not had a complete workup or in whom the AMA is negative, the biopsy may still be diagnostic of the disease.

▪ Figure 9.49 Bile lake secondary to rupture of a duct and extravasation of bile in mechanical obstruction.

In patients with clinical and laboratory features of chronic cholestasis, particular attention paid to the condition of the acinar bile ducts is critical in histologic evaluation. Ducts affected by PBC show variable chronic inflammation and epithelial injury that lead to destruction of the duct, a lesion called chronic nonsuppurative destructive cholangitis (59) or the florid duct lesion (60). It is this immunologically mediated destruction of ducts that initiates the disease. Lymphocytes and plasma cells penetrate the basement membrane and insinuate themselves between the epithelial cells, causing destruction of epithelial cells (Fig. 9.52, 9.53) and segments of the basement membrane. Eosinophils and even some neutrophils (despite the fact that it is called nonsuppurative) may be present, but it is the lymphocytes that appear to be the primary effectors of the injury. Well-developed lymphoid follicles, sometimes with germinal centers, may be found around or adjacent to the degenerating bile ducts. Epithelioid granulomas (Fig. 9.53), typically less well organized than those of sarcoidosis, are located in the portal areas adjacent to or surrounding the bile ducts, or less often in the

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parenchyma, in approximately one third of the cases.

▪ Figure 9.50 “Bile ductular cholestasis.” Periportal ductules are markedly dilated and filled with bile in a patient with bacterial sepsis.

Florid duct lesions are generally considered to be pathognomonic of PBC (53,59,60,61), but they must be distinguished from the hepatitisassociated bile duct lesions (Fig. 9.39) discussed in the preceding text under Chronic Hepatitis. This is most easily accomplished by searching for the features that accompany the destruction of ducts in PBC, namely ductopenia and chronic cholestasis. In chronic hepatitis, loss of ducts is rare and chronic cholestatic features do not develop. The degree of cholangitis in PBC varies greatly from one portal tract to another. Some ducts can appear completely normal, whereas others exhibit striking inflammation and epithelial injury. Therefore, the active diagnostic lesion can be absent in small biopsy samples, and the pathologist is then compelled to apply other criteria and clinical data to the evaluation. The number of portal tracts lacking acinar bile ducts should be estimated. With the exception of premature infants, a normal liver has a ratio of bile ducts to portal areas of 0.9 or greater (62), usually with the acinar duct running parallel to the hepatic artery branch. In most

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patients with PBC, more than half of the portal tracts lack bile ducts, that is, ductopenia (Fig. 9.54), and it is only in the earliest stages that there are no portal areas with missing ducts (62). Also helpful is the frequent presence of periportal bile pigment and cholate stasis (Fig. 9.51). P.274 P.275 These changes are often subtle and must be sought with care. Small to moderate amounts of copper-binding protein (stainable with Victoria blue) and copper (on rhodanine stain) are frequently detected in hepatocytes in the periportal area (Fig. 9.7). Periportal (zone 1) Mallory bodies, found in 10% to 15% of cases, are further evidence of chronic cholestasis. These are identical to the Mallory bodies of alcoholic and nonalcoholic steatohepatitis except for their location—the Mallory bodies of steatohepatitis are in zone 3.

▪ Figure 9.51 Cholate stasis, indicating chronic cholestasis. The affected cells have pale, foamy cytoplasm because of bile lipid retention.

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▪ Figure 9.52 Florid duct lesion of early primary biliary cirrhosis. The ductal epithelium is infiltrated with inflammatory cells (predominantly lymphocytes), the epithelial cells are severely injured, and the basement membrane is ruptured.

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▪ Figure 9.53 Florid duct lesions of early primary biliary cirrhosis. The duct has ruptured (arrow), and there is a poorly formed epithelioid cell granuloma (G) adjacent to the damaged duct.

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▪ Figure 9.54 Primary biliary cirrhosis. The portal area lacks a bile duct (ductopenia).

Ductular reaction can be prominent in PBC, particularly in the surrounding portal areas that lack acinar bile ducts. Care must be taken to distinguish the ductules from bile ducts. Hepatocytes are relatively spared, but there is invariably some element of interface hepatitis (“piecemeal necrosis”) and hepatitis-like parenchymal injury (61,63). Some investigators have distinguished what they call “biliary piecemeal necrosis,” seen in areas of cholate stasis, from “lymphocytic piecemeal necrosis” that is typical of chronic hepatitis (64), but in our experience, these occur together so often that the distinction is not meaningful. There are cases in which the biopsy specimen shows so much hepatocellular injury and interface hepatitis that an overlap syndrome of PBC and autoimmune hepatitis is considered (65,66). In such cases, the clinical and laboratory findings may also suggest both disease processes. However, in our opinion, it is the loss of bile ducts and chronic cholestatic injury that is more significant because bile ducts do not regenerate as readily as hepatocytes and it is chronic cholestasis that leads to cirrhosis in these patients. Therefore, we agree with those who consider the overlap syndrome to be a hepatitic form of PBC (67).

Primary sclerosing cholangitis

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Primary sclerosing cholangitis usually involves the entire biliary tract, but there are occasional cases that affect only extrahepatic or intrahepatic ducts. The extrahepatic ducts are thick and cord-like and have a narrowed lumen. Histologically, a variety of changes may be seen, depending in part on the integrity of the ductal system draining the biopsied area. Changes in the parenchyma are largely due to incomplete chronic mechanical biliary obstruction. Bile pigment is often minimal or absent because obstruction is rarely complete. Clues to the diagnosis can be observed in the portal areas. Some acinar bile ducts may show marked periductal fibrosis with prominent compression and distortion of the epithelium (Fig. 9.55). The epithelium may be almost unidentifiable or even completely atrophic, while a small nodule (cross section of a cord) of fibrous tissue remains in its place (Fig. 9.56). The basement membrane is intact and often thickened. The bile ducts still may be present, but they are often reduced in number or may be totally absent, depending on the stage of the disease. Ductular proliferation is relatively mild compared with that seen in other types of biliary obstruction. Chronic cholestatic features, with cholate stasis and copper accumulation, become increasingly prominent as the disease progresses and may render its distinction from PBC difficult. Furthermore, granulomas, considered a typical feature of PBC, are occasionally present in primary sclerosing cholangitis (68). However, periductal fibrosis is not a typical feature of PBC, while florid duct lesions, in particular the destruction of the basement membrane, are not observed in sclerosing cholangitis.

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▪ Figure 9.55 Primary sclerosing cholangitis. Note the marked periductal fibrosis with compression and atrophy of the epithelium.

Fibrosis follows the loss of bile ducts in both sclerosing cholangitis and PBC, although the mechanism is not clear. In PBC, at least, both ductular proliferation and interface hepatitis, accompanied by collagen deposition, appear to be important (69), but the possible roles of other factors related to chronic cholestasis have not been studied in detail. The fibrosis extends progressively with portal–portal bridging and septum formation, eventually with nodule formation and development of a micronodular biliary cirrhosis indistinguishable from that caused by chronic mechanical obstruction (Fig. 9.57). Staging of disease, if requested, is best accomplished by estimating the degree of fibrosis because any combination of histologic lesions can be found in an individual biopsy specimen. Ludwig P.276 suggested four stages for both PBC (70) and sclerosing cholangitis (71)—stage I (portal), stage II (periportal), stage III (septal), and stage IV (cirrhosis). Early stage, mid stage, and late stage are also acceptable terms, although they sound less scientific.

▪ Figure 9.56 Primary sclerosing cholangitis. The acinar bile duct

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is replaced by a fibrous nodule.

Allograft rejection Acute (cellular) rejection is an immunologically mediated attack of the host's defenses against the engrafted liver. The principal targets of the attack are the bile ducts and the endothelium of veins and arteries but not of sinusoids. Snover's triad, consisting of mixed portal inflammation (involving lymphocytes, plasma cells, neutrophils, and eosinophils), bile duct damage (Fig. 9.58) (e.g., rejection cholangitis), and endothelialitis (usually affecting portal vein branches and sometimes the central veins, in the form of lymphocytes attached to the luminal surface of the endothelial cells or between the cell and its basement membrane), is considered diagnostic of rejection (72). These features are variable, and diagnostic findings may or may not present on any individual liver biopsy, so the presence of two of the three features is usually considered sufficient for diagnosis. Cholestasis, hepatocyte ballooning, apoptotic or acidophilic bodies, and focal necrosis may also be present. Cellular rejection may be graded according to the international consensus Banff schema (72), but the clinical utility of this is yet to be proved.

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▪ Figure 9.57 End-stage biliary cirrhosis is typically micronodular with chronic cholestatic features in the residual parenchyma and thick bands of collagen between the nodules, imparting a “jigsaw” pattern to the tissue. Bile ducts are absent.

Chronic (ductopenic) rejection refers to the irreversible damage to the engrafted liver through a combination of immunologically mediated injury and ischemia. It typically follows repeated episodes of acute rejection and so is usually not diagnosed until at least several months after transplantation. Rapidly progressive cases are sometimes seen (acute vanishing bile duct syndrome) but are uncommon. The changes of chronic rejection are thought to be partly due to the injury associated with repeated acute rejection and partly due to reduced arterial flow caused by foam cell arteriopathy in large arteries of the graft. Bile ducts require an arterial blood supply, so the loss of the arteries contributes to the loss of ducts. Changes of chronic rejection include bile duct atrophy and pyknosis, loss of bile ducts (ductopenia) with or without loss of hepatic artery branches, and foam cell arteriopathy in larger arteries, particularly those near the hilum (73). The loss of ducts produces features of chronic cholestasis, and zone 3

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fibrosis may also occur because of ischemia.

▪ Figure 9.58 Acute cellular allograft rejection.

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Other chronic cholestatic syndromes Mechanical obstruction—any of the microscopic changes observed in acute biliary obstruction may be present in biopsy specimens from patients with long-standing obstruction. Additional changes that point to the chronic nature of the process commonly develop when obstruction persists for more than a few weeks. These include periductal sclerosis, cholate stasis, periportal bile stasis, copper accumulation, and sometimes Mallory body formation. Bile becomes inspissated, appearing dark olive green and laminated in sections. Loss of hepatocytes in zone 1 contributes to periportal fibrosis. Cirrhosis may develop when complete or nearly complete obstruction persists for many months, but most patients will be relieved of the obstruction or will develop complications and death before cirrhosis ensues. Biliary cirrhosis is histologically characterized by fibrous septa, linking portal tracts and outlining irregular islands of parenchyma that resemble the

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pieces of a jigsaw puzzle (Fig. 9.57). Extrahepatic biliary atresia in the neonate (see Chapter 47) is more likely to produce secondary biliary cirrhosis than other causes of mechanical obstruction. In this condition, all the morphologic features of acute and chronic biliary obstruction described in the preceding text can be observed, depending on the stage during which a biopsy specimen is obtained. The same criteria for diagnosis of biliary obstruction, described in the preceding text, must be used to differentiate biliary atresia from other cholestatic disorders of the neonate and infant. Some degree of portal fibrosis and ductular proliferation are usually present in biliary atresia and help in distinguishing it from neonatal hepatitis. Diagnostic difficulty may be caused by the presence of giant cell transformation, suggesting hepatocellular injury, in some cases of biliary atresia, but giant cell transformation in neonates should be considered a nonspecific pattern of injury, induced by a variety of hepatic and extrahepatic disorders. Sarcoidosis sometimes causes a syndrome of chronic intrahepatic cholestasis that can mimic PBC or primary sclerosing cholangitis in many clinical, biochemical, and histologic aspects (72,73,74). In such cases, the liver develops confluent granulomas that destroy bile ducts, cause chronic cholestasis, and may lead to biliary cirrhosis. Although depletion of bile ducts is characteristic, florid duct lesions are uncommon. Granulomatous inflammation in the liver can be found in portal, periportal, and parenchymal areas in the active phase of the syndrome, and the granulomas are better formed and a more dominant feature than those in PBC (Fig. 9.59).

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▪ Figure 9.59 Chronic cholestatic syndrome of sarcoidosis. This portal area has several granulomas and considerable fibrosis but lacks a bile duct.

P.278 Secondary sclerosing cholangitis with features nearly identical to primary sclerosing cholangitis may follow mechanical obstruction from a variety of causes, such as surgical manipulation of the biliary tract or tumors of the extrahepatic ducts. Secondary sclerosing cholangitis may also follow chemical injury, such as intra-arterial injection of floxuridine to treat metastatic colon cancer (75) or the injection of formalin into hydatid cysts. Langerhans' cell histiocytosis occasionally affects bile ducts, causing ductal destruction and secondary sclerosing cholangitis (76). Acquired immunodeficiency syndrome (AIDS) cholangiopathy is a form of secondary sclerosing cholangitis that follows some biliary tract infections such as cryptosporidiosis or CMV in patients with AIDS (77). Drug-induced chronic cholestasis is an uncommon complication of acute drug injury. A patient with this syndrome develops jaundice, often severe, which does not fully resolve, producing a disorder with some degree of histologic, biochemical, and clinical resemblance to PBC, but not with the insidious onset of the idiopathic forms of chronic cholestasis described in the preceding text. In the early stage there is

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an acute cholangitis, while biopsy specimens in the later stages show ductopenia and chronic cholestatic features (78). Paucity of intrahepatic bile ducts is a term used for congenital diseases that produce chronic cholestasis associated, as the name implies, with absence of the small acinar (“interlobular”) ducts (79). The best defined of these is arteriohepatic dysplasia or Alagille syndrome (see Chapter 47). Bile ducts are present at birth but undergo progressive destruction from early infancy to childhood. In later childhood, there is paucity or absence of acinar bile ducts (Fig. 9.60), paradoxically with mild cholestatic features (80,81). Despite the lack of ducts, it is rare to see bile stasis, and progressive fibrosis or cirrhosis is uncommon. By contrast, children who have bile duct paucity without the other anomalies of Alagille syndrome tend to have a much worse disease, often with progression to end-stage liver disease. Such cases are usually idiopathic but are thought to result from various types of in utero injuries that prevent the normal development of acinar ducts, resulting in a diminished number of ducts at birth. Idiopathic adulthood ductopenia is a term that is suggested for the rare patient who has a chronic cholestatic syndrome with progressive bile duct loss but does not fit into one of the entities listed in the preceding text (82).

Steatosis (Fatty Liver) Steatosis can be subclassified into two broad morphologic categories— macrovesicular and microvesicular—on the basis of the size of the fat vacuoles in the liver cells. The distinction is not always sharp, and there are cases where both macrovesicular and microvesicular fat coexist. In general, steatosis is considered macrovesicular when the hepatocytes contain a single large fat vacuole that displaces the nucleus to the edge of the cell, whereas the steatosis is microvesicular when there are numerous small cytoplasmic fat vacuoles that tend to leave the nuclei centrally placed within the hepatocytes. In routinely processed material, the lipid is dissolved by organic solvents, and so frozen sections with special stains (e.g., oil red-O) are necessary to confirm its presence in cases where there is doubt.

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▪ Figure 9.60 Paucity of intrahepatic ducts (Alagille syndrome). This medium-sized, fibrotic portal area lacks a bile duct, but there is very little inflammation or cholestatic features.

Macrovesicular steatosis is a reaction to a wide variety of injuries, many of which are subclinical and might be more properly regarded as a physiologic adaptation manifested as an imbalance between uptake of lipids from the blood and secretion of lipoproteins by the hepatocyte. Most affected hepatocytes contain a single, medium-sized or large, rounded vacuole that displaces the nucleus and cytoplasm to the periphery of the cell (Fig. 9.61). The vacuoles can be as large as or larger than a normal hepatocyte. Conditions often associated with macrovesicular steatosis include malnutrition, diabetes mellitus, obesity, malabsorption, various debilitating disorders, some metabolic diseases, corticosteroid therapy, and exposure to various other drugs and toxins. Steatosis can be the only change, or it may be associated with other lesions. For example, P.279 in chronic hepatitis C, there is often macrovesicular steatosis associated with the other changes described in the preceding text. Steatohepatitis (alcoholic or nonalcoholic), several metabolic diseases (e.g., Wilson disease), and drug-induced injury (e.g., methotrexate) may be associated with fat accumulation, along with other lesions characteristic of the disease. The location of the fat is quite variable; it is usually

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diffuse but can be predominantly in zone 1 or 3.

▪ Figure 9.61 Macrovesicular steatosis. Most hepatocytes contain a single, large, rounded vacuole that displaces the nucleus and cytoplasm to the periphery of the cell.

Microvesicular steatosis generally connotes a more serious injury than macrovesicular steatosis, although it has been shown that this is a frequent nonspecific finding, especially in autopsy material (83,84). Consequently, a diagnosis of one of the diseases characterized by microvesicular steatosis cannot be made without compatible clinical and laboratory findings. Hepatocytes with microvesicular steatosis show a central nucleus surrounded by sharply defined small vacuoles (Fig. 9.62). Acute fatty liver of pregnancy (85) and Reye's syndrome (86) are well-recognized causes of microvesicular steatosis. A number of metabolic diseases, including fatty acid oxidation disorders, mitochondrial oxidation chain disorders, and urea cycle disorders, are associated with microvesicular steatosis and can mimic Reye's syndrome to varying degrees (87,88). Toxic injury from drugs such as tetracycline, aspirin, valproic acid, antiretroviral nucleoside analogs, and fialuridine can also produce microvesicular steatosis (50,89,90,91). Alcoholic liver injury can also occasionally lead to a toxic microvesicular steatosis, a lesion called alcoholic foamy degeneration (92). South American epidemics of hepatitis D and B coinfection are found to have

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marked microvesicular steatosis (93) for unknown reasons. Other forms of viral hepatitis, both acute and chronic, may have some degree of microvesicular steatosis, especially if frozen sections and oil red-O stains are used to demonstrate its presence. However, in general fat stains should be reserved for situations in which there is a high clinical suspicion of one of the diseases in which microvesicular steatosis is a cardinal feature, such as acute fatty liver of pregnancy.

▪ Figure 9.62 Microvesicular steatosis in acute fatty liver of pregnancy. Hepatocytes have a central nucleus surrounded by numerous small fat vacuoles.

Steatohepatitis: Alcoholic Hepatitis and Nonalcoholic (Metabolic) Steatohepatitis Steatohepatitis Steatohepatitis is the term used for the morphologic pattern of injury characteristic of the active phase of alcoholic liver disease. Synonyms include alcoholic steatonecrosis, sclerosing hyaline necrosis, and alcoholic hepatitis, when it is found in persons who consume large quantities of alcohol, and fatty liver P.280

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hepatitis, metabolic steatohepatitis, and nonalcoholic steatohepatitis, when it occurs in nondrinkers. Because the morphology is so similar, regardless of cause, the term steatohepatitis is used here when the lesion is referred to, and alcoholic hepatitis or nonalcoholic steatohepatitis is used for the clinicopathologic entities. Because the pathologist is often unaware of the pertinent clinical information, a diagnosis of steatohepatitis is acceptable until it is known whether the patient consumes alcohol. In patients who are alcoholic, it is presumed that the liver disease represents direct toxicity from ethanol. In those who do not drink, the pathogenesis of the liver disease remains obscure and seems most likely to represent some form of metabolic (probably genetic) disease related to obesity with insulin resistance and/or diabetes (see Chapter 39). It should be emphasized that every liver biopsy specimen with fat and inflammation is not steatohepatitis, despite the name. For example, a patient with preexisting steatosis may have hepatitis-like spotty necrosis and inflammation from an unrecognized drug, undiagnosed virus, or oxidative stress of other unknown cause, but this is not considered steatohepatitis. Only when there are other changes, as described in the subsequent text, is the term steatohepatitis appropriate. Steatohepatitis, whatever the cause, is a chronic lesion that predominantly affects acinar zone 3 (94). Microscopically, this is characterized by a constellation of features that vary in degree and extent from patient to patient. In addition to steatosis (usually macrovesicular but sometimes microvesicular or “mixed”), as noted in the preceding text, there is ballooning of liver cells, most prominently in zone 3. Globular cytoplasmic inclusions, representing enlarged, damaged mitochondria, may be present, as well as Mallory bodies.

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▪ Figure 9.63 Ultrastructural appearance of a Mallory body. It consists of a tangled mass of intermediate filaments.

Mallory bodies represent a form of cellular injury that results from a derangement of the intermediate filament component of the cytoskeleton of liver cells (95). These filaments, which can be seen by electron microscopy (Fig. 9.63), have been shown to be composed of cytokeratin proteins, both those that are normally found in hepatocytes (types 8 and 18) and other types of keratin, mixed with unidentified high-molecular-weight components and coated with the heat shock protein, ubiquitin, and the regulatory protein p62. The presence of Mallory bodies induces a neutrophilic inflammatory cell response (Fig. 9.64); sometimes a ring of neutrophils surrounds the Mallory body (“satellitosis”). Neutrophils migrate into liver cells containing Mallory bodies, and their degranulation is one of the major factors contributing to the hepatocellular damage (96). Steatosis resolves within 3 to 4 weeks of abstinence from alcohol, while Mallory bodies may take months to disappear. Mallory bodies are P.281 eosinophilic and may be short and irregular or long and rope-like. The cytoplasm around large Mallory bodies is typically empty or rarified (Fig. 9.65), but sometimes it remains eosinophilic and granular (Fig. 9.66), making the Mallory body hard to detect. In mild cases the small Mallory bodies may be few and particularly hard to see (Fig. 9.67), so

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immunostains for ubiquitin (Figs. 9.12, 9.64, 9.68) or p62 protein are particularly helpful in this setting. When Mallory bodies cannot be found despite diligent search, the diagnosis is less certain, but the presence of fat and pericellular fibrosis, described next, strongly suggests steatohepatitis. This is particularly helpful in biopsies from patients with nonalcoholic steatohepatitis, because they tend to have fewer Mallory bodies and less severe active injury than patients with clinical alcoholic hepatitis.

▪ Figure 9.64 Neutrophilic “satellitosis.” In this immunostain for ubiquitin, the dark-staining Mallory bodies (arrows) have incited a neutrophilic inflammatory cell response.

Continued activity of steatohepatitis is associated with progressive pericellular fibrosis in acinar zone 3 (Fig. 9.69), with a lattice-like or “chicken-wire” appearance in sections stained with connective tissue stains. Continued scarring also leads to periportal fibrosis and occlusive lesions of terminal hepatic venules (97). With progression of disease, fibrous septa begin to link the chicken-wire fibrosis in zone 3 to extensions of the periportal fibrosis, eventually leading to complete encirclement of islets of hepatic parenchyma. The cirrhosis that develops is usually micronodular (Fig. 9.70), but a macronodular pattern can evolve after alcohol withdrawal. In patients with nonalcoholic steatohepatitis, after cirrhosis develops, the underlying

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steatohepatitis may become quiescent with disappearance of fat, active injury, and Mallory bodies, leaving the patient with a histologically cryptogenic cirrhosis (98).

▪ Figure 9.65 A Mallory body (arrow) in a ballooned hepatocyte is easily detected by routine microscopic examination.

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▪ Figure 9.66 Mallory bodies (arrows) in this case of alcoholic hepatitis are less easily seen because the hepatocytes are not as ballooned, but heavy eosin staining brings them out.

Other diseases with features of steatohepatitis Indian childhood cirrhosis (which occasionally is diagnosed in other countries) is thought to be due to copper toxicity in susceptible children (99). Histologically, the liver shows advanced micronodular cirrhosis with marked copper overload. Fat accumulation is generally mild or absent, but there is considerable hepatocellular injury with ballooning, and Mallory bodies are numerous in many cases. Drug-induced liver disease from a few drugs may demonstrate Mallory bodies and other features of steatohepatitis (50). Amiodarone and perhexiline maleate are the best characterized of these. Mallory body formation has also been attributed to estrogens, glucocorticoids, calcium channel blockers, and antiretroviral drugs, but the evidence for these is less convincing.

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▪ Figure 9.67 Mallory bodies (arrow) in a case of mild nonalcoholic steatohepatitis. The Mallory bodies in this case are all small and thin, making them difficult to find. Note the two neutrophils adjacent to the Mallory body.

P.282 After jejunoileal bypass surgery, some patients developed severe steatohepatitis (100), leading to death from hepatic failure in a few cases. Similarly, steatohepatitis has been reported occasionally in patients with postsurgical short gut syndrome and gastroplasty. Other diseases with Mallory bodies include chronic cholestatic syndromes such as PBC and primary sclerosing cholangitis, although in these diseases the Mallory bodies are in zone 1 rather than zone 3 and other features of steatohepatitis are lacking. Wilson disease may have Mallory bodies in the cirrhotic stage and can have steatosis as well, making it difficult to distinguish this disease from steatohepatitis. Finally, tumors of hepatocellular origin, including hepatocellular carcinoma, hepatocellular adenoma, and occasionally, focal nodular hyperplasia may contain Mallory bodies in the tumor cells.

Granulomatous and Suppurative Diseases

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Space-occupying inflammatory lesions Abscess is the term used for a collection of neutrophils (i.e., “pus” or purulent inflammation) in a confined space. A microscopic focus of neutrophils may be termed a microabscess. This is the typical lesion of some disseminated infections such as listeriosis and salmonellosis, as discussed in the preceding text under “Acute Necroinflammatory Disease”. Other bacterial infections that gain access to the liver—blood borne, secondary to an intra-abdominal infection, or through the biliary tract, secondary to mechanical obstruction and ascending cholangitis— cause a typical pyogenic abscess (see Chapter 48). When the abscess is due to ascending cholangitis and the remnants of a bile duct can be found in the lesion, the term cholangitic abscess (Fig. 9.48) is appropriate. Pylephlebitic abscesses are secondary to an acute ascending pylephlebitis from a focus of abdominal suppuration. As an abscess heals, chronic inflammation and scarring can be seen around the edges, with compression and destruction of the hepatic parenchyma.

▪ Figure 9.68 Numerous Mallory bodies in a case of alcoholic hepatitis are easily seen with the immunostain for ubiquitin.

Amebic abscess is not a true abscess. It is a mass of amorphous, necrotic tissue infected with amebas. The amebic trophozoites (Fig.

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9.71) can be found at the edges of the lesion, but inflammation is minimal unless there is bacterial superinfection. Inflammatory pseudotumor (101) is a mass of chronic inflammatory cells (in particular plasma cells), xanthomatous histiocytes, myofibroblasts, and fibroblasts (Fig. 9.72). Its pathogenesis is uncertain, but at least some cases result from healing abscesses. Some cases are suspected to be true neoplasms, and the term inflammatory myofibroblastic tumor is used.

▪ Figure 9.69 Steatohepatitis with early pericellular (“chickenwire”) fibrosis in acinar zone 3, best appreciated with the Masson stain.

P.283 Granuloma is a compact, organized collection of mature mononuclear phagocytes (Fig. 9.73) that may or may not be accompanied by accessory features, such as other types of inflammatory cells, necrosis, or scarring (102,103,104). Granulomatous inflammation is a response to an injury that cannot be contained and eliminated by the usual acute inflammatory response. Granulomas evolve in three stages: (i) An infiltrate of young mononuclear phagocytes, (ii) the maturation and aggregation of these cells into a mature granuloma, and (iii) the potential further maturation of these cells into an epithelioid granuloma (102). A small focus of granulomatous inflammation, consisting of only a few epithelioidhistiocytes, is often called a granulomatoid focus. The term granulomatous hepatitis should be reserved for cases in which there are both granulomas and necroinflammatory hepatocellular injury, as discussed in the preceding text under Necroinflammatory Diseases. The many causes of hepatic granulomas are discussed in Chapter 52. In the broadest sense, granulomas can be classified as infectious or

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noninfectious.

▪ Figure 9.70 Alcoholic micronodular cirrhosis in a needle biopsy.

▪ Figure 9.71 Amebic trophozoites (dark-staining) are easily seen with the PAS stain. They are present in the amorphous, necrotic

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tissue at the edge of an amebic abscess.

P.284

Infectious granulomas Infectious granulomas may be due to any class of organism, and these can sometimes be identified in the tissue or there may be other features to provide a clue to the diagnosis: Viruses. Granulomatoid foci or, rarely, true granulomas may be seen in the liver in some viral infections, such as infectious mononucleosis and CMV mononucleosis. Other features of mononucleosis hepatitis are invariably present. Rickettsia. Q fever (Coxiella burnetii infection) typically produces granulomas with a distinctive, although not pathognomonic, appearance (Fig. 9.74) (105,106). These lesions have a central fat vacuole surrounded by epithelioid histiocytes and other inflammatory cells. Brightly eosinophilic strands of fibrin form a ring within the granuloma, so these lesions are called fibrin ring granulomas. Similar granulomas are described occasionally in patients with a number of other diseases (CMV, EBV, hepatitis A, AIDS, boutonneuse fever, staphylococcal sepsis, toxoplasmosis, visceral leishmaniasis, allopurinol toxicity, giant cell arteritis, Hodgkin's disease, and lupus erythematosus) (103). In each case these are unusual manifestations of the diseases, whereas the fibrin ring granulomas are typical of Q fever hepatitis. The organisms cannot be identified in tissue, but finding fibrin ring granulomas should prompt serologic testing for Coxiella burnetii.

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▪ Figure 9.72 Inflammatory pseudotumor is a mass of inflammatory cells, histiocytes and fibroblasts, presumably the result of a healing inflammatory lesion.

Bacteria. True granulomas are unusual in most bacterial diseases except in brucellosis and occasionally in syphilis; organisms are almost never demonstrable. Microabscesses or ill-formed granulomas that contain neutrophils suggest a bacterial infection such as catscratch disease, melioidosis, tularemia, or typhoid. Mycobacteria. Caseous necrosis (Fig. 9.75) should suggest miliary tuberculosis, although acid-fast bacilli may be difficult or impossible to find. Absence of caseation, of course, does not exclude tuberculosis. Lepra bacilli are difficult to find in granulomas in tuberculoid leprosy, but they can be demonstrated in large numbers with special stains in untreated lepromatous leprosy in enlarged reticuloendothelial cells that have a foamy cytoplasm (lepra cells) and are clustered in granuloma-like formations (107). Similarly, patients with AIDS P.285 and disseminated Mycobacterium avium intracellulare frequently have hepatic involvement with “macrophagic” granulomas composed of hypertrophied, grey–blue macrophages containing hundreds of acid-fast bacilli (Fig. 9.76) (108). Giant cells and

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inflammatory cells are generally absent, as is caseous necrosis.

▪ Figure 9.73 Typical noncaseating granulomas in a patient with sarcoidosis. The granulomas are composed predominantly of epithelioid histiocytes. The smaller granuloma in the lower part of the field probably represents a tangential cut through a larger lesion.

Fungi. Granulomas in the systemic mycoses often contain the fungal spores or hyphae that may be visible with hematoxylin and eosin but are best demonstrated with the Gomori methenamine silver stain (Fig. 9.77). Protozoa. Organisms in visceral leishmaniasis are usually found in hypertrophied Kupffer cells, but granulomas may be seen, sometimes with central necrosis and sometimes with fibrin rings (103). Parasites. Several parasitic diseases can involve the liver with a granulomatous response (103). By far the most important of these is schistosomiasis. The granulomas in this disease usually contain intact eggs (Fig. 9.78) or their chitinous remnants. The granulomas in the same biopsy specimen can be of differing ages, from “active” granulomas with many epithelioid cells and eosinophils to round scars containing fragments of egg chitin.

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Granular black schistosomal pigment, which is the acid hematin residue from breakdown of host hemoglobin by the parasite, is usually readily identified in the reticuloendothelial cells in livers harboring active granulomas. Other parasitic diseases in which eggs can be found in association with a granulomatous response include hepatic capillariasis, fascioliasis, paragonimiasis, and ascariasis. Visceral larva migrans, usually attributable to the larvae of Toxocara species, produces a characteristic lesion in the liver. The granulomas are associated with a massive outpouring of eosinophils and often reveal areas of central necrosis resulting from degeneration and degranulation of eosinophils (Fig. 9.79); there can be Charcot-Leyden crystals in the necrotic foci, but larvae are only rarely identified (109).

▪ Figure 9.74 Fibrin ring granuloma in Q fever (Coxiella burnetti infection) has a central fat globule surrounded by epithelioid cells and a brightly eosinophilic ring of fibrin (arrows).

Noninfectious granulomas Sarcoidosis is the prototype of all granulomatous diseases. It is always a diagnosis of exclusion, requiring demonstration of granulomas in two or more tissues with exclusion of all known causes of granulomatous disease. At least 90% of patients with sarcoidosis have hepatic

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involvement, although in most it is clinically insignificant. Granulomas in sarcoidosis have no specific identifying features, but they do tend to have certain characteristics. The granulomas are scattered P.286 P.287 throughout the liver tissue, but most tend to be portal or periportal. Granulomas of all ages are typically present. The earliest lesions consist of small, loosely arranged clusters of a few epithelioid cells within the acini. Older lesions are globular or ovoid and sharply defined (Fig. 9.73), and in cases with severe involvement, the granulomas may be confluent. Young granulomas tend to be composed predominantly of epithelioid cells, often with a few lymphocytes, while giant cells are a sign of aging. The giant cells may contain asteroid bodies (Fig. 9.80), Schaumann bodies, or calcium oxalate crystals. Older granulomas often have many giant cells, and sometimes, when the granulomas have resolved, a few naked giant cells may remain in the tissue. Usually, however, sarcoid granulomas heal by scarring, and often there is a rim of dense collagen around each granuloma (Fig. 9.81). The last remnant is a fibrous nodule, sometimes containing one or two giant cells. The granulomas in sarcoidosis are typically noncaseating, but rarely caseous necrosis may be seen in otherwise typical cases (74).

▪ Figure 9.75 Miliary tuberculosis with amorphous, caseous necrosis in the centers of the granulomas.

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▪ Figure 9.76 Disseminated Mycobacterium avium intracellulare in a patient with acquired immunodeficiency syndrome. The liver contains “macrophagic” granulomas composed of hypertrophied, grey–blue macrophages. Acid-fast stains typically show hundreds of acid-fast bacilli.

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▪ Figure 9.77 Gomori methenamine silver stain is useful for demonstrating fungal organisms in systemic mycoses. Yeast forms can be seen in this case of histoplasmosis.

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▪ Figure 9.78 Schistosomiasis. This portal granuloma contains an embryonated egg.

▪ Figure 9.79 Visceral larva migrans. This eosinophilic granuloma consists of a central area of necrotic eosinophils surrounded by a palisade of epithelioid histiocytes and an outer zone that contains many additional eosinophils.

In most patients with sarcoidosis, the hepatic granulomas are clinically silent. An unknown proportion of patients, however, come to clinical attention because of clinical symptoms and signs of cholestatic liver disease, portal hypertension, or abnormal liver test results. Biopsy results in such cases show a spectrum of changes (74). Some patients have only sarcoid granulomas without other associated changes, but the majority show some degree of associated necroinflammatory injury (e.g., apoptosis, focal necrosis, chronic portal inflammation), features of chronic cholestasis (e.g., cholate stasis, bile duct loss), or some combination of these. Extensive portal fibrosis may cause severe bile duct loss leading to a biliary cirrhosis, or there may be fibrous obliteration of portal vein branches, producing portal hypertension.

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▪ Figure 9.80 Sarcoidosis. An old fibrotic granuloma containing several giant cells, one of which has an asteroid body (arrow).

In a significant proportion of patients a cause is never found for the sarcoid-like hepatic granulomas, and no extrahepatic granulomas are found to confirm the diagnosis of sarcoidosis. Nevertheless, such cases probably represent the same idiopathic disease, but until the cause of sarcoidosis is discovered, these cases will remain undiagnosed. Sarcoid-like granulomas can be seen in PBC, chronic berylliosis, brucellosis, drug-induced injury, and in many miscellaneous conditions. Some diseases are characterized by lesions other than the granulomas that suggest the diagnosis. For example, the liver in PBC also reveals chronic cholestasis and cholangiodestructive lesions in portal areas. Drug-induced granulomas can be accompanied by hepatocellular injury or combined hepatocellular and cholestatic injury, as is typical of the liver injury associated with several drugs (23,50).

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▪ Figure 9.81 Sarcoidosis. Old, partially healed granulomas are surrounded by fibrosis and contain both epithelioid histiocytes and giant cells.

P.288 Lipogranulomas in the liver are a common finding, the result of the accumulation of ingested mineral oil (110). They consist of variable numbers of fat vacuoles, histiocytes, mononuclear cells, and sometimes eosinophils or neutrophils, and there can be some associated focal fibrosis (Fig. 9.82). Typically, lipogranulomas are located in portal areas or in the vicinity of terminal hepatic venules.

Metabolic Diseases Identification of storage products In the broadest sense, the term storage can be used to include various lesions and diseases characterized by the abnormal or excessive accumulation of a metabolite or substance in one of the cellular or extracellular compartments of the liver. This may include storage in hepatocytes, reticuloendothelial cells (Kupffer cells or other macrophages), stellate cells, and other mesenchymal cells, canaliculi, ductules, bile ducts, space of Disse, and other parts of the vasculature. Storage may indicate an inherited metabolic disease (111), or it may be

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part of some other process. When an abnormal substance is noted, it can often be identified by its appearance in routine sections and by its reactions with special histochemical stains. Special techniques, such as transmission or scanning electron microscopy, fluorescence or polarizing microscopy, or immunohistochemistry, may help in select cases.

▪ Figure 9.82 Three small lipogranulomas, composed of mineral oil droplets, macrophages, and chronic inflammatory cells.

Pigment storage is one of the more common lesions. This can be recognized as brown, green, or black material, which may be stored in hepatocytes, macrophages, or canaliculi. Bile pigment varies from brown to green and may be found in canaliculi, ductules, or ducts in cholestatic diseases (see preceding text), which rarely presents an identification problem. Bile pigment in hepatocytes and Kupffer cells can usually be distinguished from other pigments by a characteristic green color in a Hall's stain for bile or by a greenish brown color in a Prussian blue iron stain. Lipofuscin pigment varies from dark brown to golden brown. It is found in hepatocytes (“wear and tear” pigment) as a normal part of aging and in increased amounts in patients with chronic drug ingestion and Dubin-Johnson syndrome; it is found in Kupffer cells as the breakdown product of phagocytosed cellular debris when there has been necroinflammatory injury or other forms of tissue necrosis. Lipofuscin stains positively with argentaffin and PAS stains (Fig. 9.4)

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and negatively with the iron stain. Hemosiderin is brown and coarsely granular and refractile in routine stains. It accumulates in hepatocytes, Kupffer cells, and mesenchymal cells to varying P.289 degrees in hemochromatosis and other iron overload states, and, like lipofuscin, it accumulates in Kupffer cells when there has been necroinflammatory injury. Hemosiderin stains positively with the Prussian blue stain for iron (Fig. 9.6), and so this stain can be easily used in most cases to distinguish the three brown pigments from one another. Glycogen storage is a physiologic function of the hepatocytes. In the fed state, glycogen can be demonstrated in liver cell cytoplasm with the PAS stain, and predigestion with diastase will abolish the staining. If glycogen storage disease is suspected, a portion of the biopsy specimen should be fixed in alcohol, rather than formalin, because this is the most suitable fixative for the histochemical demonstration of glycogen. In glycogen storage diseases, the glycogen often accumulates to such an extent that the hepatocytes appear swollen and plant-like (Fig. 9.83) (111). Definitive diagnosis, however, depends on the demonstration of the specific enzymatic defect. Type IV glycogen storage disease differs from the other types and is the only type that can be readily diagnosed on liver biopsy (112). This type is associated with the accumulation of an abnormal glycogen molecule, an amylopectin-like material, in hepatocytes. This distinctive material is homogeneous and slightly eosinophilic or even colorless. It typically appears as a circumscribed inclusion (Fig. 9.84) displacing the remainder of the cytoplasm and the nucleus to the periphery and stains intensely with PAS, Best's carmine, colloidal iron, and Lugol's iodine. The inclusions resist digestion with diastase or amylase but can be digested with pectinase.

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▪ Figure 9.83 Type I glycogen storage disease. Periodic acid-Schiff stain (left) shows that the enlarged hepatocytes are filled with glycogen, which is removed by diastase digestion (right), showing the liver cells to have a clear, finely vesiculated cytoplasm.

Proteins and glycoproteins are stored in hepatocytes in several conditions. Proteins stain with eosin in routine hematoxylin and eosin sections, so they can be recognized as storage material when they form discrete cytoplasmic inclusions. α 1 -Antitrypsin (AAT) deficiency (see Chapter 37) is the best-characterized disorder with protein storage. AAT, a major protease inhibitor (Pi) in serum, is a glycoprotein that is synthesized predominantly by the liver to function as a modulator of the inflammatory response by inhibiting proteases. Individuals with one or both AAT alleles of the “Z” phenotype are unable to transport and secrete newly synthesized AAT molecules normally through the endoplasmic reticulum and Golgi apparatus of the hepatocyte, resulting in low concentrations of AAT in the serum. Faulty secretion of abnormal AAT molecules coupled with defective degradation of these molecules retained in the Golgi apparatus leads to the formation of characteristic eosinophilic globules in hepatocytes (Fig. 9.85) (113). The globules are PAS positive and diastase resistant (Fig. 9.5) due to the carbohydrate moieties of the glycoprotein. These are typically found in patients who are homozygous or heterozygous for PiZ, but they can also occur in other phenotypes, even sometimes in patients with the normal PiM phenotype (114,115). In the noncirrhotic liver, the characteristic AAT globules are located in periportal hepatocytes.

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P.290 They are round, homogeneous, and eosinophilic, and vary from 1 to 40 µm in diameter. Usually, they are separated from the remainder of the cytoplasm by a halo that is probably artifactual. Immunohistochemical staining can confirm that the globules are composed of AAT but cannot be used to determine the phenotype. PAS-positive globules are usually not detectable in infants younger than 3 months, although some present with neonatal hepatitis or paucity of bile ducts. Liver biopsy specimens from adults with AAT deficiency may reveal only the characteristic globules in periportal regions, or there may be erosion of the limiting plate associated with chronic inflammation and periportal fibrosis, similar to chronic hepatitis of other etiologies, or cirrhosis with globules at the periphery of the nodules.

▪ Figure 9.84 Type IV glycogen storage disease. The abnormal glycogen metabolite accumulates in cytoplasmic inclusions.

Other protein storage disorders, both inherited and acquired, may produce cytoplasmic inclusions. α 1 -Antichymotrypsin deficiency and antithrombin III deficiency are rare, but both are associated with AATlike PAS-positive globules (116,117). Familial fibrinogen storage disease produces globular inclusions that are eosinophilic but only weakly PASpositive because of a lower carbohydrate content (118). Plasma protein inclusions (119), consisting of a mixture of circulating proteins imbibed

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by hepatocytes from the plasma, are seen most often in hepatic congestion. They are variably PAS positive and may be globular or have a pale eosinophilic appearance that can be confused with the groundglass inclusions of hepatitis B. PAS-positive, diastase-resistant, groundglass–appearing inclusions are also seen in patients taking the drug cyanamide (120) (not used in the United States) and in patients with Lafora's disease (myoclonus epilepsy) (121).

▪ Figure 9.85 α 1 -Antitrypsin deficiency. The hepatocytes contain eosinophilic globules of α 1 -antitrypsin stored in endoplasmic reticulum cisternae.

Lipids, glycolipids, sphingolipids, and other phospholipids accumulate in a number of inherited and acquired conditions. Hepatocytes, Kupffer cells, and stellate cells that contain a lipid storage product generally appear clear, vacuolated, or foamy. Triglyceride is by far the most common storage product, and this is discussed separately in the preceding text under Steatosis. All lipids stain positively in unprocessed frozen sections with the oil red O and Sudan black stains. Most, however, do not survive routine processing in organic solvents, so their demonstration requires forethought because a portion of the specimen must be handled separately. To avoid the artifacts of frozen section, the tissue can be postfixed in osmium tetroxide, which stains the lipid black (Fig. 9.86) (122). Cholesterol esters are stored along with triglyceride

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in the two forms of lysosomal acid lipase deficiency, Wolman's disease and cholesterol ester storage disease, causing the hepatocytes to appear swollen and pale. Both types of lipid stain with oil red O, but the cholesterol can also be demonstrated in frozen P.291 sections with a Schultz stain (1). Glucosylceramide, a glycolipid, accumulates in Kupffer cells in Gaucher's disease (lysosomal glucocerebrosidase deficiency), producing the distinctive striated appearance of Gaucher's cells. The PAS stain after diastase digestion provides an excellent demonstration of these cells because enough of the carbohydrate component of the storage product survives processing and stains positively (Fig. 9.87). Sphingomyelin accumulates in Kupffer cells in the many variants of Niemann-Pick disease, producing a foamy appearance (Fig. 9.88). Other phospholipids accumulate in both Kupffer cells and hepatocytes in drug-induced phospholipidosis because of chronic ingestion of amphophilic drugs such as amiodarone (50). The Kupffer cells appear foamy, but the hepatocellular phospholipid storage can generally only be recognized by electron microscopy (Fig. 9.89). Vitamin A is stored in stellate cells (formerly called perisinusoidal lipocytes or Ito cells), and these become prominent in individuals ingesting excess vitamin A (Fig. 9.90). Lipid globules containing the vitamin A are apparent with fat stains, and vitamin A is autofluorescent in frozen sections. Mineral oils (paraffins) are common in the Western diet, and some are absorbed and stored in portal macrophages or lipogranulomas near terminal hepatic venules (Fig. 9.82). In frozen sections the mineral oil stains a pale salmon with the oil red O stain.

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▪ Figure 9.86 Osmium stain for fat. Lipids stain black when the tissue is postfixed in osmium tetroxide. In this patient with hypervitaminosis A, the stellate cells (perisinusoidal lipocytes) are hypertrophied because of vitamin A storage, and there are a few small triglyceride droplets in hepatocytes.

▪ Figure 9.87 Gaucher's disease. Striations in the Gaucher's cells are nicely demonstrated by the PAS stain after diastase digestion.

Mucopolysaccharides accumulate in both hepatocytes and Kupffer cells in Hunter and Hurler diseases (Fig. 9.91), other mucopolysaccharidoses, and mucolipidoses. The affected cells appear swollen and finely vacuolated. Colloidal iron, alcian blue, and other stains for mucopolysaccharides are positive, and the PAS stain after diastase digestion is also positive. Oligosaccharides in diseases such as sialidosis are stored in hepatocyte lysosomes, making the liver cells appear vacuolated. Porphyrins accumulate in the liver in porphyria cutanea tarda and erythropoietic protoporphyria (see Chapter 38). Uroporphyrin crystals in hepatocytes are P.292 P.293 inapparent by routine stains, but these can sometimes be demonstrated with a ferric ferricyanide stain (123) in patients with porphyria cutanea tarda. Protoporphyrin deposits in erythropoietic protoporphyria appear as brownish red globular masses in hepatocytes and bile canaliculi. They are easily mistaken for bile pigment, but with polarized light they

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are red with characteristic Maltese cross birefringence (Fig. 9.15) (13).

▪ Figure 9.88 Niemann-Pick disease. Sphingomyelin accumulates in Kupffer cells, giving them a foamy appearance. Liver cells appear normal.

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▪ Figure 9.89 Phospholipidosis in a patient taking amiodarone. Ultrastructurally the hepatocyte cytoplasm contains numerous lamellated whorls of phospholipid.

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▪ Figure 9.90 Hypervitaminosis A. Stellate cells (arrows) are engorged with stored vitamin A.

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▪ Figure 9.91 Hurler disease. The stored mucopolysaccharide gives the swollen liver cells a finely vacuolated appearance.

Copper storage in hepatocytes in chronic cholestatic diseases or in Wilson disease is not visible by light microscopy, but it is often found in association with periportal or periseptal lipofuscin granules. Stains for copper, such as rhodanine (Fig. 9.7), are needed for demonstrating storage because it can easily be missed. Crystals of various types may be stored in macrophages under special conditions. Many crystals are birefringent with polarized light, and scanning electron microscopy with x-ray spectrophotometry can specifically identify those that are inorganic. In cystinosis, crystals of cystine can be demonstrated with the polarizer in the tissue that has been fixed in alcohol. Birefringent talc crystals (Fig. 9.14) or black, nonbirefringent titanium dioxide pigment granules can sometimes be found in macrophages of some patients who are or had been intravenous drug abusers. Other foreign materials, such as gold (which appears as a black pigment in patients treated with gold for rheumatoid arthritis), thorium dioxide (Thorotrast, a discontinued radiologic contrast material), polyvinyl pyrrolidone (a discontinued plasma expander), and anthracotic carbon (in coal miners), may be found stored in reticuloendothelial cells.

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Genetic hemochromatosis As the most common hepatic storage disease, biopsy diagnosis of hemochromatosis deserves special mention. Gene analysis and quantization of iron concentration in liver tissue obtained by biopsy are now the preferred method for diagnosis (see Chapter 36), but examination of the biopsy specimen is still useful in distinguishing primary from secondary iron overload and in assessing the degree of fibrosis. Secondary iron overload is the proper term for nongenetic causes of excess tissue iron. This may be due to multiple blood transfusions, chronic hemolysis, or prolonged dietary overload, but it rarely results in tissue damage except in a few extreme instances. Hemosiderosis is the term used for morphologically identifiable iron accumulation in tissue, whatever the cause. Severe hemosiderosis is usually due to genetic hemochromatosis, but it can be secondary to transfusional or dietary iron or chronic hemolysis. In such cases the hemosiderin accumulation is predominantly in reticuloendothelial cells. Excess iron may accumulate in hepatocytes of patients with damaged livers, especially in alcoholic cirrhosis and also in chronic viral hepatitis. Many of these patients are probably heterozygous for genetic hemochromatosis. In homozygous genetic hemochromatosis, iron accumulates over the course of the patient's life (124). In young homozygous patients, this is detected as a progressive increase in hepatocellular hemosiderin pigment (most prominently in periportal regions) with minimal or no other pathologic changes (Fig. 9.92). As the quantity of iron increases, the cells of zones 2 and 3 become affected. Scattered apoptotic bodies and foci of necrosis are found infrequently. Kupffer cells may ingest small quantities of iron. By middle age in men or after menopause in women, enough iron has usually accumulated to cause hepatocellular necrosis, portal inflammation, and portal and bridging fibrosis. Alcohol and intercurrent liver diseases such as hepatitis C may accelerate iron accumulation. Fibrous septa eventually creep from the portal areas into the surrounding parenchyma. Evidence of regeneration is not apparent in the precirrhotic stage, but a reticulin stain can demonstrate plates greater than one cell in thickness near the portal tracts. The fibrous septa can P.294 show variable ductular proliferation, but inflammation is mild or absent.

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▪ Figure 9.92 Hemochromatosis. This iron stain of a biopsy from a young homozygous patient shows a marked increase in hepatocyte stainable iron (dark granules), most prominently in acinar zone 1. There is no fibrosis as yet.

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▪ Figure 9.93 Micronodular cirrhosis of hemochromatosis. The iron stain shows marked deposition of hemosiderin (dark granules) in liver cells, bile ducts, and mesenchymal cells of the fibrous septa.

Fibrous bands from adjacent portal tracts eventually join and dissect the parenchyma into irregular micronodules (Fig. 9.93). By this stage there is marked hemosiderin deposition with heavy pigment staining of hepatocytes, bile duct epithelium, ductules, and mesenchymal cells of the fibrous septa and vessels. Relatively less iron is found in Kupffer cells. Regeneration is not usually prominent, but regenerative nodules offer striking contrast to the remaining parenchyma by their lack of stainable iron, so-called iron-free foci (125). Hepatocellular carcinomas that develop in hemochromatotic livers are also devoid of iron, and there is evidence that the iron-free foci represent preneoplastic lesions.

Wilson disease Tissue damage in Wilson disease (see Chapter 35) is related to excess copper, and the liver is the earliest site of progressive copper accumulation, after which the copper is released into the blood to accumulate in other organs. The histopathologic changes (126,127,128) are not specific and must be evaluated in conjunction with clinical and laboratory findings. Hepatic copper concentration can be measured in the tissue obtained by needle biopsy and can provide a definitive

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diagnosis when other tests are equivocal. Biopsy specimens obtained from young siblings of patients with this disease may show little or no hepatic damage. The earliest microscopic lesions include steatosis, periportal glycogenated nuclei, and rare foci of necrosis or apoptotic bodies. Although the hepatic copper content is elevated, copper is usually not histochemically identifiable at this stage, but ultrastructural changes in hepatic mitochondria, thought to be characteristic if not pathognomonic, are present (Fig. 9.94). These include pleomorphism, separation of the inner and outer membranes, enlarged intercristal spaces, and various types of inclusions (6,129). More advanced cases show lesions that resemble chronic hepatitis of other cause. Mallory bodies, with their characteristic neutrophilic response, may be present in the liver cells in zone 1. Copper may be demonstrable in the periportal areas with appropriate stains. A variety of patterns of cirrhosis can develop in the later stages but a macronodular type is the most common (Fig. 9.95). Regenerative foci lack identifiable copper, so absence P.295 of stainable copper in a cirrhotic biopsy, particularly if the sample is small, does not rule out Wilson disease. On the other hand, a large amount of copper in a cirrhotic liver is strongly suggestive of Wilson disease (Fig. 9.7).

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▪ Figure 9.94 Wilson disease. Ultrastructurally, the mitochondria have a dense matrix with separation of the membranes of the cristae.

▪ Figure 9.95 Wilson disease, end stage. Macronodular cirrhosis is present with large nodules separated by bands of scar tissue.

Vascular Disorders Vascular patterns of injury Certain patterns of injury in the liver are typical, if not pathognomonic, of a vascular disease. Congestion, atrophy, and coagulative necrosis are all findings that suggest a vascular component to the underlying disorder. A variety of substances, both endogenous and foreign, can be deposited in the vasculature as well. Ischemia. Acute ischemic injury typically produces zone 3 (“centrilobular”) coagulative necrosis, similar to that seen in severe injury from certain toxins, such as acetaminophen overdose or mushroom poisoning. Ischemic injury may follow shock, left-sided heart

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failure, or right-sided failure associated with hypotension (130,131). Clinically, the presentation may mimic viral hepatitis (ischemic hepatitis) (132). Liver cells that have undergone coagulative degeneration are shrunken, have an intensely eosinophilic cytoplasm, and show nuclear pyknosis or lysis (Fig. 9.20). When an inflammatory response is present, it is invariably neutrophilic. Kupffer cells are hypertrophied and usually full of lipofuscin. Clearing of the dead hepatocytes leads to condensation of reticulin fibers and fibrosis in some cases. Atrophy. Chronic ischemic injury produces atrophy of acini or liver cell plates. Mild forms of chronic ischemia are a fairly common consequence of aging. Mild portal fibrosis with some periductal fibrosis and reduction in portal vein diameter is a frequent finding in elderly individuals. Often there will be areas in the liver in which vascular structures appear close together, indicating that the acini have atrophied (Fig. 9.96). Extreme forms of this phenomenon can result in hepatoportal sclerosis (also called idiopathic portal hypertension, noncirrhotic portal hypertension, or noncirrhotic portal fibrosis) (133) or nodular regenerative hyperplasia (134) when there is heterogeneous blood flow through portal vein branches and hepatic arterioles with atrophy of the affected acini and compensatory hyperplasia of other acini (Fig. 9.97). Both conditions may cause portal hypertension in the absence of cirrhosis. Atrophy of the left lobe and segmental atrophy (Fig. 9.98) (135) are usually due to severe compromise of the vasculature (inflow or outflow) to a portion of the liver, but this may also be due to bile duct occlusion.

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▪ Figure 9.96 Atrophy, secondary to chronic ischemia. Portal areas are fibrotic and close together, indicating atrophy of the acini.

▪ Figure 9.97 Nodular regenerative hyperplasia. The entire hepatic parenchyma is replaced by hyperplastic nodules separated by atrophic liver cell plates.

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Venous outflow obstruction The terminal hepatic venules (“central veins”), intercalated (“sublobular”) veins, hepatic veins, and inferior vena cava form the venous outflow tract, but only the terminal hepatic venules and intercalated veins are commonly sampled by liver biopsy. Obstruction of any portion of the outflow tract can be followed by changes in other vessels, such as sinusoidal dilatation and, rarely, thrombosis of portal venules. Chronic congestive heart failure or constrictive pericarditis can mimic outflow tract obstruction when severe. Hepatic vein thrombosis (Budd-Chiari syndrome) produces histologic findings that are commonly confused with congestive heart failure or drug-induced injury and must be interpreted with care. Many of the

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changes do resemble those of congestive heart failure, but differ by showing variability of involvement among acini, particularly well visualized with open (wedge) biopsy specimens. Those acini with acute changes show severe sinusoidal dilatation and congestion, most pronounced in zone 3 (Fig. 9.99), but sometimes extending to the portal tracts. Coagulative degeneration or necrosis is frequently present. Erythrocytes in the congested areas are packed into the spaces of Disse and crowd the degenerating hepatocytes. The terminal hepatic venules and intercalated veins can show thrombosis, recanalized thrombi (Fig. 9.99), and/or fibrous mural thickening, but in a small biopsy specimen the veins that are sampled may be normal. Some acini are injured in a more gradual manner. Progressive sinusoidal dilatation is accompanied by atrophy of hepatocytes. Zone 3 fibrosis can follow either type of injury and can link adjacent terminal hepatic venules. Small portal veins may also become occluded, further augmenting the injury to parts of the liver (136). Other acini are entirely spared. The caudate lobe is often uninvolved because of its separate venous drainage and can undergo compensatory hypertrophy.

▪ Figure 9.98 Segmental atrophy. The tissue is fibrotic, and there are portal areas and ductules, but hepatocytes are missing, presumably because of chronic ischemia.

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Veno-occlusive disease resulting from toxic injury (e.g., from pyrrolizidine alkaloids) or radiation damage to the endothelium of the small outflow produces parenchymal changes that resemble those of Budd-Chiari syndrome, but in the early stages, lesions of the terminal hepatic venules and intercalated veins are distinctive. Intimal edema is followed by the subendothelial deposition of reticulin and collagen fibers and progressive narrowing of the lumen (Fig. 9.100). Extravasated erythrocytes are frequently P.297 situated between the fibers. Inflammation is sparse or absent, and superimposed thrombi are not seen. Cases with severe acute injury may show necrosis of venous walls. With progressive fibrosis of the walls, the veins become difficult to identify, appearing as small hyalinized cylinders. Involvement of hepatic veins or the vena cava does not occur in most cases.

▪ Figure 9.99 Budd-Chiari syndrome. Organizing thrombus in a large intercalated vein (V) is associated with severe sinusoidal dilatation and congestion and necrosis of zone 3 of the surrounding

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acini.

Sinusoidal lesions Dilatation of sinusoids is a frequent finding in liver biopsy specimen and is often a nonspecific reaction to systemic disease. Chronic congestive heart failure leads to the gradual development of dilatation and congestion of sinusoids and finally to atrophy of hepatocytes, predominantly in zone 3, with secondary fibrosis (130,131). A characteristic type of periportal (zone 1) sinusoidal dilatation sometimes follows the use of oral contraceptives (137). Liver plates show variable degrees of atrophy (Fig. 9.101). The change affects all acini, unlike the focal sinusoidal dilatation seen sometimes near hepatic masses. Panacinar sinusoidal dilatation can be found in sickle cell disease; the dilated sinusoids are packed with masses of sickled erythrocytes. Variable dilatation, lacking any particular zonal localization, can be associated with other disorders, notably neoplasms and granulomatous diseases. Sinusoidal dilatation of the liver may be a systemic manifestation of a number of neoplasms. A characteristic triad of histologic changes, consisting of focal sinusoidal dilatation, proliferation of ductules, and infiltration of edematous portal areas by neutrophils, has been observed in the vicinity of space-occupying lesions (138).

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▪ Figure 9.100 Veno-occlusive disease associated with Senecio alkaloid toxicity. The efferent vein has a markedly narrowed lumen because of intimal thickening with extravasation of erythrocytes. There is zone 3 necrosis and marked congestion.

Peliosis hepatis is characterized by scattered lakes of blood of varying sizes, which appear to represent an extreme degree of localized sinusoidal dilatation (Fig. 9.102). The pathogenesis of the process is now considered to be due to endothelial injury that allows blood to accumulate in spaces of Disse with resultant formation of the cavities. In the past, peliosis was recognized as a complication of debilitating disorders, such as tuberculosis and malignancies, and was discovered at autopsy as an incidental finding. Currently, the most frequent cause is therapy with androgenic/anabolic steroids (139). Histologically, the peliotic lakes may have an attenuated endothelial lining. Varying degrees of sinusoidal dilatation can be present near some of the lesions, but the term peliosis hepatis should not be used for simple sinusoidal dilatation. Bacillary angiomatosis due to Bartonella henselae in patients with AIDS (140) P.298 can mimic peliosis, but stains for bacteria typically demonstrate numerous organisms.

▪ Figure 9.101 Marked periportal sinusoidal dilatation associated with long-term oral contraceptive steroid use. The liver cell plates are atrophic.

Thrombosis of sinusoids with deposition of fibrin thrombi is unusual, but

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it happens in some diseases. Patients with toxemia of pregnancy usually have no evidence of liver disease; those who do frequently have deposits of fibrin in periportal sinusoids (141). Occasionally, the deposits are associated with coagulative-type hepatocellular necrosis. Disseminated intravascular coagulation can be associated with a similar pattern of injury, but the sinusoidal fibrin deposition need not be restricted to the periportal areas.

▪ Figure 9.102 Peliosis hepatis associated with anabolic steroid therapy. Variable-sized lakes of blood are scattered throughout the parenchyma.

Fibrosis of sinusoids occurs in many chronic diseases. Collagen is deposited in the space of Disse along with laminin, forming basement membranes and leading to capillarization of the sinusoids. The collagen is well demonstrated with a Masson stain, and many components of basement membranes and extracellular matrix can be demonstrated with specific immunostains. Sinusoidal fibrosis is prominent in zone 3 of the acinus in the early stages of alcoholic hepatitis (Fig. 9.69), nonalcoholic steatohepatitis, diabetes mellitus, chronic congestive heart failure, and vitamin A hepatotoxicity.

Amyloidosis Patients with amyloidosis frequently have hepatic involvement, and liver

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biopsy has been advocated as a means of establishing the diagnosis. Amyloid can be limited to the arteries but can also be found in the parenchyma (Fig. 9.103). In both primary amyloidosis (type AL) and secondary amyloidosis (type AA), the eosinophilic material gradually accumulates in the space of Disse (142), eventually leading to atrophy of the hepatic plates. The presence of amyloid can be confirmed by an appropriate stain, either histochemical (e.g., Congo red with apple green dichroism P.299 under polarized light) or immunohistochemical, with a specific antibody to the amyloid.

▪ Figure 9.103 Extensive intra-acinar amyloid deposition filling the space of Disse between the hepatocytes and endothelial cells, producing atrophy of the liver cell plates.

Cirrhosis Cirrhosis is defined as a diffuse process characterized by fibrosis and conversion of the normal liver architecture into structurally abnormal nodules (143). Three basic morphologic categories are recognized on the basis of the size of the cirrhotic nodules. The micronodular type includes those cases in which almost all nodules are less than 3 mm in diameter. In the macronodular type, most nodules are greater than 3

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mm in diameter and usually show striking variation in size. The mixed pattern is characterized by approximately equal numbers of micro- and macronodules. Regenerative nodules are not essential for the diagnosis of cirrhosis; in both biliary cirrhosis and hemochromatosis, for example, regeneration may be minimal or absent.

▪ Figure 9.104 Fragmented needle biopsy specimen from a cirrhotic liver. The Masson stain shows collagen of the fibrous septa enveloping and traversing the fragments.

The diagnosis of cirrhosis may be difficult to establish by percutaneous needle biopsy, particularly if the pattern is macronodular. Cutting needles (e.g., Tru-cut) are preferred because these obtain specimens that include the fibrous septa and the parenchymal nodules (Fig. 9.104). Suction techniques (e.g., Menghini needles) are limited by preferential sampling of parenchyma as the biopsy needle rebounds from the fibrous septa. There are, however, a number of microscopic clues to the diagnosis, even in this type of specimen. Suction biopsies from cirrhotic livers are commonly fragmented, and the fragments have rounded edges Fibrous septa can course through the fragments, but these are sometimes represented by thin strips hugging margins of the fragments. Stains for collagen (Fig. 9.104) are frequently necessary to detect them. Such stains are also valuable for distinguishing collapsed reticulin that follows extensive necrosis from fibrosis and for demonstrating thick liver plates in regenerative nodules of the cirrhotic liver. Reticulin stains usually demonstrate a very irregular pattern because of alterations in the growth of hepatocytes. Many cell plates are greater than one cell in thickness, P.300 and the compressed sinusoidal spaces may be nearly invisible. Hepatocytes are pleomorphic, unless the process is entirely inactive. An

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alteration of the spatial relationship between the portal vessels and central veins is typical. Micronodular cirrhosis is less difficult to establish by needle biopsy than is macronodular cirrhosis because the diameter of the biopsy needle usually exceeds that of the small cirrhotic nodules. The capsule of the liver in many noncirrhotic patients is thickened by an increase in fibrous tissue, vessels, and ductules. A small biopsy specimen from such an area (particularly a superficial wedge biopsy) should be interpreted with caution and not diagnosed as cirrhosis. The morphologic approach in cirrhosis should include an assessment of whether the cirrhosis is fully developed or incomplete, the basic morphologic type (i.e., micronodular, macronodular, or mixed), the degree of activity, and the presumptive cause, if possible. Biopsy specimens showing occasional nodules or extensive fibrosis may be judged to represent early or incomplete cirrhosis, but the designation cirrhosis should be reserved for those with complete loss of acinar architecture. An assessment of the activity should take into account the degree of hepatocellular degeneration and necrosis and the amount of inflammation in the parenchyma of the nodules. Every effort to establish the underlying cause should be made, although this is not always possible. An etiologic diagnosis can sometimes be established by changes observed in hematoxylin and eosin–stained sections alone (e.g., absence of bile ducts and chronic cholestasis indicating biliary cirrhosis, including cirrhosis secondary to PBC or primary sclerosing cholangitis). Special stains, however, are an important auxiliary technique. Particularly useful are copper stains for Wilson disease and PBC, the PAS stain and immunostains for α 1 antitrypsin deficiency, immunostains of the antigens of hepatitis B, and an iron stain for hemochromatosis. Putative preneoplastic lesions may be found in cirrhotic livers. Large cell change (liver cell dysplasia) is characterized by nuclear and cytoplasmic enlargement, nuclear hyperchromasia, prominent nucleoli, and occasionally, multinucleation (Fig. 9.105) (144). Dysplastic nodule is the term used for grossly or radiologically distinctive nodules that are usually larger than the surrounding cirrhotic nodules and that may differ in color or texture (145). These are classified microscopically as low-grade dysplastic nodules when there are minimal atypical histologic features. They are classified as high-grade dysplastic nodules when there are atypical features in the hepatocytes of the nodule, such as cytoplasmic basophilia, high nuclear/cytoplasmic ratios, nuclear irregularity, and hyperchromasia. High-grade dysplastic nodules often have ill-defined nodules within the large nodule (“nodule-in-nodule” formation), best recognized by compression of surrounding reticulin fibers and different orientation of the liver plates. These are often composed of smaller than normal hepatocytes with high nuclear– cytoplasmic ratios, a feature termed small cell change (or small cell

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dysplasia) (Fig. 9.106). Evidence suggests that this lesion, rather than large cell change, is more likely the precursor of hepatocellular carcinoma in the cirrhotic liver.

▪ Figure 9.105 Large cell change (liver cell dysplasia) in cirrhosis. Dysplastic cells are large and contain large dark-stained and sometimes irregular nuclei.

Fibropolycystic Diseases Lesions and types of cysts Von Meyenburg complexes or biliary microhamartomas are a common developmental anomaly in the liver (146,147). They are typically found adjacent to normal portal areas and consist of a fibrous stroma that contains several irregular duct-like structures lined by biliary epithelium (Fig. 9.107). These are often somewhat dilated and some may be large enough to be considered cysts. They often contain eosinophilic or bilestained secretions. Bile duct cysts are usually solitary and lined by a cuboidal biliary-type epithelium. These are considered to be of developmental origin, and at least some arise from cystic dilatation of a von Meyenburg complex, although in most cases, there are no clues to the P.301

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exact pathogenesis of the lesion. The cysts typically contain clear fluid, but become infected and contain pus, or when large, there may be hemorrhage and inflammation secondary to minor trauma.

▪ Figure 9.106 Small cell dysplasia in a high grade dysplastic nodule. There is a nodular growth of small liver cells with high nuclear/cytoplasmic ratios (arrows) within a large cirrhotic nodule.

Ciliated foregut cyst is an unusual type of developmental cyst that is lined by ciliated columnar epithelium (148). These cysts are analogous to bronchogenic cysts of the mediastinum. They are extremely rare in the liver. Ductal plate malformation refers to the persistence of the embryonic ductal plate in the postnatal liver (147). In embryonic life, before the appearance of the acinar bile ducts, the portal tracts are surrounded by a layer of biliary-type cells, termed the ductal plate. This structure normally disappears as the true bile duct develops in the center of the portal area. Persistence of parts of the ductal plate may give rise to von Meyenburg complexes, duct-like structures seen in congenital hepatic fibrosis, and cysts of infantile polycystic disease (Fig. 9.108).

Infantile polycystic disease Infantile polycystic disease, which is an autosomal recessive disease, is

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part of a spectrum of lesions that includes infantile polycystic kidney disease, congenital hepatic fibrosis, and Caroli's disease (149). Expression varies from individual to individual. The liver in childhood polycystic disease is enlarged and firm, but cysts are not usually visible grossly. Microscopic sections show numerous irregular duct-like structures in the portal areas. These have apparent branching and irregular angulated extensions into the acini (Fig. 9.108), and there is often a circular arrangement of the ducts, complete or interrupted, characteristic of the ductal plate malformation. In contrast to congenital hepatic fibrosis, relatively little fibrous tissue is present. The ducts are slightly dilated, but true cysts are rare. They are lined by a simple, low columnar to cuboidal epithelium.

▪ Figure 9.107 A von Meyenburg complex, which has a dense stroma containing irregular small duct-like structures, a few of which are slightly dilated.

Congenital hepatic fibrosis In congenital hepatic fibrosis, thick collagenous bands form an extensive network, usually continuous, that links adjacent portal tracts (Fig. 9.109). Numerous bile duct–like structures, some slightly irregular and dilated, are situated in the fibrous septa and sometimes contain mucin or bile. Although they resemble bile ducts, they actually

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represent ductal plate remnants. Portal vein branches often appear reduced in size and number, and the sparsity of venous channels might account in part for the portal hypertension. The irregular intervening parenchyma frequently has a “jigsaw” P.302 pattern reminiscent of that seen in biliary cirrhosis. However, unlike cirrhosis, congenital hepatic fibrosis does not show evidence of parenchymal destruction or regeneration. The hepatocytic plates are regular and one cell in thickness, and there is an abrupt transition between the normal-appearing hepatocytes and the collagenous septa.

▪ Figure 9.108 Infantile polycystic disease. The ducts are lined by cuboidal epithelium, show polypoid intraluminal projections, and are for the most part empty. They arise from remnants of the embryonic ductal plate.

Adult polycystic disease Adult polycystic disease is frequently associated with adult polycystic kidney disease. Numerous cysts, varying from less than 1 mm to more than 12 cm in diameter, are present, containing clear, colorless or straw-colored fluid, unless infected. Microscopically, the cysts appear to originate in the portal areas. They are lined by low columnar to cuboidal

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epithelium (Fig. 9.110) and have a collagenous supporting stroma that can be infiltrated by a few inflammatory cells. Von Meyenburg complexes (biliary microhamartomas) are frequently present, and components of the complexes sometimes lie adjacent to the cysts, suggesting that the cysts evolve from progressive dilatation of the biliary channels in the complexes. Occasional cases show many von Meyenburg complexes and no cysts.

▪ Figure 9.109 Congenital hepatic fibrosis. This Masson stain shows islands of parenchyma separated by irregular bands of fibrous tissue that contain numerous small ductal plate remnants.

Tumors Hepatocellular tumors Hepatocellular adenoma. This is composed of benign hepatocytes arranged in sheets and cords without an acinar architecture (Fig. 9.111) (150). It is easily mistaken for normal liver if the absence of portal areas is not noticed. The tumor cells are the same size or slightly larger than non-neoplastic hepatocytes and often have a pale cytoplasm because of an increased glycogen and/or fat content. The nuclei are uniform and regular, and the nuclear–cytoplasmic ratio is normal; mitoses are almost never seen. Thin-walled vascular channels are

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scattered throughout the tumors, but large arteries are only seen around the periphery. The sinusoids are usually compressed with flattened lining cells, contributing to the sheet-like appearance. Sometimes the sinusoids are dilated, a finding that has mistakenly been called peliosis. Kupffer cells are present but usually inconspicuous, and hematopoietic cells may also be found in sinusoids. Focal nodular hyperplasia. This is usually a solitary nodule with a typical gross appearance that is extremely useful in making the diagnosis (150). The lesions are well circumscribed but unencapsulated. When on the surface of the liver, they may appear umbilicated. They P.303 are usually of a lighter color than the surrounding liver, ranging from yellow to tan or light brown. The cut surface typically contains a central “stellate” scar with radiating fibrous septa dividing the lesion into nodules.

▪ Figure 9.110 Adult polycystic disease. Multiple cysts of varying size are lined by cuboidal to flattened epithelium.

The microscopic features correspond to the gross pathology. A section through the center of the lesion nearly always shows the central “stellate” scar that usually contains one or more large arteries, often with abnormal intimal or medial fibromuscular proliferation (Fig. 9.112). Proliferating ductules are usually present but true bile ducts are

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lacking. Fibrous septa of variable size radiate from the central scar. Between the septa are hyperplastic nodules of normal hepatocytes with cholestatic features, such as cholate stasis, and copper storage, and even bile pigments are usually present to some degree and are occasionally prominent, making the lesion resemble a focal area of biliary cirrhosis. A needle biopsy is easily misinterpreted as cirrhosis unless one is aware that it is from a solitary lesion, but the large artery in an area of scarring provides a valuable clue to the diagnosis. Hepatocellular carcinoma. The cells of hepatocellular carcinoma resemble normal liver cells to a variable extent (151). In some tumors, the cells are so well differentiated that they are difficult to distinguish from normal hepatocytes or from the cells of hepatocellular adenoma. At the other extreme are tumors with cells that are anaplastic and poorly differentiated, showing only minimal evidence of liver cell origin. Most tumors, however, show definite evidence of hepatocellular differentiation. The tumor cells have distinct cell membranes and an eosinophilic, finely granular cytoplasm. Bile canaliculi are usually present between cells (Fig. 9.113) and, although sometimes hard to find, can usually be seen by light microscopy. Immunostains for CEA are useful for demonstrating canaliculi because of a CEA cross-reacting substance called biliary glycoprotein I (BGP-1) located in the canalicular membrane. Bile pigment may be present in tumor cells or in dilated canaliculi and is the most helpful microscopic feature in establishing the diagnosis. The tumor cell nuclei are usually large, producing a high nuclear–cytoplasmic ratio. They show variable degrees of anaplasia and usually have prominent nucleoli.

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▪ Figure 9.111 Hepatocellular adenoma, composed of a sheet-like growth of large, pale hepatocytes without acinar architecture. Compressed normal liver tissue is present in the lower part of the picture.

Several histologic growth patterns may be found in hepatocellular carcinoma, and because the cytologic features can be so variable, recognition of one of these patterns can be helpful in arriving at a diagnosis. Most frequent is the trabecular pattern (Fig. 9.114) in which the tumor cells grow in thick cords that attempt to recapitulate the cell plate pattern P.304 of the normal liver. The trabeculae are separated by vascular spaces (sinusoid-like) with very little or no supporting connective tissue. Sometimes the centers of the trabeculae contain dilated canaliculi, producing a pseudoglandular pattern, while solid patterns are produced when the trabeculae grow together, forming sheets of tumor cells.

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▪ Figure 9.112 Focal nodular hyperplasia. A section through the central scar shows an abnormally thickened large artery (arrow). Cirrhosis-like nodules surround the central scar.

Fibrolamellar hepatocellular carcinoma. This is usually considered to be a histologic variant of hepatocellular carcinoma, but there is considerable evidence that it is actually a completely different biologic entity, occurring in a different population with a better prognosis than the other types of hepatocellular carcinoma. The pathologic features of fibrolamellar carcinoma are quite distinctive (152). Microscopically, these tumors appear to be well-differentiated hepatocellular carcinomas but instead of trabeculae separated by sinusoids, they are composed of sheets of large polygonal tumor cells separated by abundant collagen bundles arranged in parallel lamellae (Fig. 9.115), hence the name fibrolamellar. The tumor cells have a characteristic cytologic appearance with cytoplasm that is deeply eosinophilic and granular due to the presence of numerous mitochondria. Approximately 50% of these tumors have cytoplasmic “pale bodies” that represent intracellular fibrinogen storage.

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▪ Figure 9.113 Moderately differentiated hepatocellular carcinoma with several dilated canaliculi (C) easily visible between tumor cells.

Hepatoblastoma. Epithelial hepatoblastoma is composed of fetal- or embryonal-type liver cells, or both (153). Tumors with predominantly fetal cells mimic fetal liver with a distinctive light-and-dark cell pattern and foci of hematopoiesis (Fig. 9.116). Embryonal cells are smaller and more basophilic with a high nuclear–cytoplasmic ratio. They tend to form acini, tubules, or papillary structures. Mixed epithelial– mesenchymal hepatoblastoma has an epithelial component of either fetal or embryonal cells and also a mesenchymal-like element that may consist of primitive mesenchyme, osteoid (with or without calcification), and rarely cartilage or rhabdomyoblasts. An anaplastic type (small cell undifferentiated) and a macrotrabecular type (hepatocellular carcinomalike) of hepatoblastoma have also been recognized.

Biliary tumors Bile duct adenoma (peribiliary gland hamartoma) is usually a solitary subcapsular nodule, although occasional livers have more than one nodule. The lesions may be up to 4 cm in diameter, but 90% are 1 cm or less. They are composed of a proliferation of small, round, normalappearing ducts with cuboidal, slightly basophilic cells that have very

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regular nuclei and lack any evidence of dysplasia or mitotic figures (Fig. 9.117). There is P.305 P.306 always a fibrous supporting stroma that may be dense and hyalinized. Preexisting normal or inflamed portal areas may be present within the tumor. Although these lesions have traditionally been regarded as benign tumor of bile ducts, recent studies have shown the tumor cells to have the immunophenotype of normal peribiliary glands, indicating that they are actually peribiliary gland hamartomas (154).

▪ Figure 9.114 Trabecular growth pattern of hepatocellular carcinoma. The tumor cells form thick cords (resembling islands of cells in cross section), separated by vascular spaces mimicking hepatic sinusoids.

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▪ Figure 9.115 Fibrolamellar hepatocellular carcinoma. The tumor cells are large and polygonal and (in contrast to the trabecular hepatocellular carcinoma) are embedded in a fibrous stroma arranged in parallel lamellae.

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▪ Figure 9.116 Fetal hepatoblastoma mimics fetal liver with a distinctive “light-and-dark” cell pattern and small clusters of hematopoietic cells.

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▪ Figure 9.117 Bile duct adenoma (peribiliary gland hamartoma). The tumor is a localized proliferation of small benign glands in a fibrous stroma.

Cholangiocarcinoma. Microscopically, these resemble adenocarcinomas arising in other parts of the body (155). They are glandular carcinomas (Fig. 9.118) composed of cells resembling biliary epithelium. The cells are low columnar or cuboidal with slightly basophilic cytoplasm and nuclei that are smaller than those of hepatocellular carcinoma; nucleoli are inconspicuous. Mucin can often be demonstrated by special stains but is seldom abundant. There is typically a dense fibrous stroma, which can be helpful in their distinction from hepatocellular carcinoma but not from metastases. Calcifications can sometimes be seen in the fibrous tissue. The tumors are usually well-differentiated gland-forming neoplasms, but they may be poorly differentiated, papillary, or solid, displaying the full range of appearances that can be seen in adenocarcinomas. Occasional tumors show focal squamous differentiation (adenosquamous or mucoepidermoid carcinoma). There are no reliable histologic features distinguishing intrahepatic cholangiocarcinoma from metastatic adenocarcinoma. The diagnosis depends on the reasonable exclusion of an extrahepatic primary.

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▪ Figure 9.118 Cholangiocarcinoma can resemble an adenocarcinoma arising anywhere in the body. There is typically a dense fibrous stroma infiltrated by irregular glands composed of pleomorphic tumor cells.

Biliary cystadenoma and cystadenocarcinoma. These are multilocular cystic neoplasms that arise from intra- and extrahepatic bile ducts (155). Developmental cysts are never truly multilocular (although secondary changes occasionally make them seem so). Cystadenomas and cystadenocarcinomas may occur anywhere in the intra- or extrahepatic bile ducts, but nearly all are partly or totally within the liver. Most are over 10 cm in diameter. Microscopically, biliary cystadenoma has a mucin-secreting columnar epithelium lining the cysts (Fig. 9.119). The lining cells have a pale eosinophilic cytoplasm and basally oriented nuclei, typical of biliary-type epithelium. The epithelium is supported by what has been called a mesenchymal stroma. This is compact and cellular, and resembles the stroma of the ovary. Biliary cystadenoma is regarded as a premalignant tumor, and when malignancy develops, it is called cystadenocarcinoma. There may only be in situ carcinoma with papillary growth into the cysts, or there may be frank invasive adenocarcinoma.

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▪ Figure 9.119 Cystadenoma is a multilocular cystic neoplasm with mucinous epithelium overlying a compact mesenchymal stroma.

P.307 Biliary papillomatosis is an extremely rare disease in which multiple benign papillary adenomas, similar to adenomas of the intestinal tract, arise in the bile ducts (154). As with intestinal adenomas, invasive carcinoma may develop.

Hemangiomas and Other Vascular Tumors Hemangiomas are the only common vascular tumors of the liver. Most are less than 4 cm in diameter, but occasional tumors may be as large as 30 cm. Microscopically these are cavernous hemangiomas with varying-sized vascular channels (Fig. 9.120) lined by flattened endothelial cells (156). They are usually discrete and well demarcated from the surrounding liver, although an occasional hemangioma may contain trapped bile ducts or foci of parenchyma. Variable amounts of fibrous tissue separate the vascular channels. Many consist of thin, delicate strands, while others have large areas of scarring. Fresh and organizing thrombi may be found in the vascular channels. The dynamics of these thrombi are not known, but they are commonly observed in surgically resected hemangiomas. Because of the sluggish blood flow through these tumors, small thrombi are probably constantly

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forming and lysing, contributing to the typically heterogeneous appearance by MRI. Fibroblasts can be found growing into a few thrombi and are probably the source of the scarring that results in the “sclerosing hemangioma.” In end-stage sclerosed and/or calcified hemangiomas, an underlying vascular pattern can usually still be discerned, providing the clue to the diagnosis.

▪ Figure 9.120 Hemangioma consists of a fibrous stroma containing “cavernous” blood-filled spaces lined by flattened endothelial cells.

Other vascular tumors are exceedingly rare. Infantile hemangioendothelioma is a rare tumor that can occur in the liver in infants (156). They consist of small proliferating capillary-like vascular channels, similar to the capillary hemangiomas that are common in the skin and mucous membranes of infants. Although histologically benign, they may become large enough to cause hepatic failure or high-output congestive heart failure due to shunting through the tumor. Angiosarcoma is a rare highly malignant tumor in which atypical endothelial cells proliferate in hepatic sinusoids (Fig. 9.121), causing hepatocyte atrophy and formation of vascular channels and sometimes solid masses of tumor (157). Epithelioid hemangioendothelioma is an equally rare malignant tumor (although not so aggressive as angiosarcoma), in which plump, epithelioid-appearing endothelial cells

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proliferate in the hepatic vasculature, producing a dense fibrous stroma (Fig. 9.122), similar to that seen in cholangiocarcinoma and metastatic adenocarcinoma (157). P.308 Many of these are misdiagnosed as adenocarcinoma or, if the tumor cells are few, as a benign lesion.

▪ Figure 9.121 Angiosarcoma is a proliferation of malignant endothelial cells that fills the hepatic sinusoids, causing the hepatocytes to atrophy.

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▪ Figure 9.122 Epithelioid hemangioendothelioma is a malignant tumor that forms intracellular capillary lumina and typically produces a dense fibrous stroma as it fills the vascular spaces.

Metastases Metastases far outnumber primary liver tumors, so that any liver mass is more likely to be metastatic than primary. Only if a tumor is benign or shows clear evidence of hepatocellular differentiation, indicating hepatocellular carcinoma, can it be confirmed that it is primary in the liver. Any other malignancy, particularly an adenocarcinoma, should be presumed to be metastatic. Microscopically, metastases usually resemble the primary tumor. If the primary lesion is known and has been biopsied or excised, comparison of the microscopic appearance of the tumor in the liver with that of the primary will confirm whether the hepatic tumor is a metastasis.

Annotated References Desmet VJ, Gerber M, Hoofnagel JH, et al. Classification of chronic hepatitis: diagnosis, grading and staging. Hepatology 1994;19:1513–1520.

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The preferred classification of chronic hepatitis. Ishak KG, Goodman ZD, Stocker JT. Tumors of the liver and intrahepatic bile ducts. Atlas of tumor pathology, Third Series, Fascicle 31. Washington, DC: Armed Forces Institute of Pathology, 2001. The authoritative book on the pathology of liver tumors. MacSween RNM, Burt AD, Portmann BC, et al., eds. Pathology of the liver, 4th ed. London: Churchill Livingstone, 2002. Overall, the best reference book on liver pathology. Prophet EB, Mills B, Arrington JB, et al., eds. Laboratory methods in histotechnology. Washington, DC: Armed Forces Institute of Pathology, 1992. A book on how to do the special stains. Scheuer PJ, Lefkowitch JH. Liver biopsy interpretation, 7th ed. London: WB Saunders, 2006. A very readable, up-to-date text book.

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144. Anthony PP, Vogel CL, Barker LF. Liver cell dysplasia: a premalignant condition. J Clin Pathol 1973;26:217–223.

145. International Working Party. Terminology of nodular hepatocellular lesions. Hepatology 1995;22:983–993.

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Editors: Title:



Copyright ©2007 Lippincott Williams & Wilkins > Table of Contents > Volume I > Section II - General Considerations > Chapter 10 Mechanisms of Liver Injury

Chapter 10 Mechanisms of Liver Injury Harmeet Malhi Gregory J. Gores

Key Concepts z

Apoptosis is a prominent feature of acute and chronic liver disease.

z

Various cell types in the liver can be affected by injurious stimuli.

z

z

Death receptor-mediated, mitochondria-dependent cell death is common in liver injury. Apoptosis leads to inflammation and injury in acute liver diseases, and in chronic liver diseases sustained apoptosis begets fibrosis.

z

Manipulation of apoptotic pathways has wide therapeutic potential.

The liver is in constant cellular flux with careful removal of senescent or damaged cells and controlled repopulation through a progenitor cell compartment. The unique juxtaposition to the intestine, large resting blood flow, and unfiltered contact with portal blood also provides the liver with a unique sensitivity to various gut-derived, diet-derived, or blood-borne insults. Under basal conditions, removal of hepatocytes occurs mainly through apoptosis without reactive inflammation. Liver injury, on the other hand, is associated with cell death, inflammation, and regeneration. Cell death in the liver can be apoptotic or necrotic or a combination of the two. Historically, apoptosis, or programmed cell death, has been viewed as a carefully choreographed cascade resulting in protease and endonuclease activation. It has been defined morphologically on the basis of characteristic nuclear appearance, the generation of membrane-bound apoptotic bodies (Councilman bodies), and the absence of an inflammatory reaction. Necrotic cell death has been considered the antithesis of apoptotic cell death. It has been defined on the basis of cellular energy depletion, characteristic morphology of cytoplasmic vacuolation, cell swelling, and the presence of an inflammatory reaction. Cell swelling, a cardinal feature of necrosis, results from an inability to maintain ion gradients, such that the process is in fact called oncotic necrosis. Over the last few years, with better understanding of both pathways of cell death, these arbitrary morphologic definitions have become less important. It is recognized that both apoptosis and necrosis can be triggered by the same stimulus and occur in the same disease process. Apoptosis has been shown to be a prominent feature of several liver diseases (Fig. 10.1). The dogma has shifted from apoptosis being a physiologic, bland, noninflammatory process to one that is pathologic, occurs in disease processes, and causes liver inflammation, injury, and fibrosis (Fig. 10.2). This

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chapter discusses mechanisms of liver injury. It is divided into two sections. The first section provides a general overview of mechanisms of death in the liver. Apoptosis and necrosis are both discussed with emphasis on death receptors (DRs) and the role of mitochondria in cell fate. The second section focuses on liver injury in some common disorders.

Basic Mechanisms Apoptosis Liver apoptosis is a prominent feature of most liver disorders, including druginduced liver disease, viral liver disease, alcoholic liver disease, nonalcoholic liver disease, cholestatic liver disease, and vascular liver disease. Apoptosis of hepatocytes, Kupffer cells, sinusoidal endothelial cells (SECs), hepatic stellate cells (HSCs), and cholangiocytes has been observed in different liver diseases (1,2,3,4,5,6). The initiation of apoptosis occurs by P.314 two fundamental pathways: (i) The DR or extrinsic pathway and (ii) the mitochondrial or intrinsic pathway (7). The extrinsic pathway is triggered by ligation or oligomerization of DRs. The mitochondrial pathway is activated by several intracellular perturbations, including deoxyribonucleic acid (DNA) damage, lysosomal permeabilization, endoplasmic reticulum (ER) stress, chemotherapeutic agents, oxidative stress, toxins, and sustained increases in Ca 2 + (8). Cells that die through the extrinsic pathway are classified as type I or type II cells. In type I cells, amplification and conduction of death signals occurs exclusive of mitochondrial involvement. In type II cells, DR activation is not sufficient to propagate a lethal signal without mitochondrial involvement. Hepatocytes are type II cells and have an obligate need for mitochondria in cell death (9).

▪ Figure 10.1 Hepatocyte apoptosis in human liver. Photomicrograph of a hematoxylin–eosin–stained section from the liver of a patient with primary sclerosing cholangitis shows several apoptotic hepatocytes (white arrow heads). Condensed nuclei (pyknosis) surrounded by an eosinophilic cytoplasm are seen.

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▪ Figure 10.2 Hepatocyte apoptosis promotes fibrosis. The link between hepatocyte apoptosis and fibrosis is illustrated here. Apoptosis is the proximal event in hepatic fibrosis. Apoptotic hepatocytes are engulfed by stellate cells, leading to their activation, and by Kupffer cells, leading to the secretion of several proinflammatory and proapoptotic cytokines. Kupffer cell–derived cytokines promote stellate cell activation and further promote apoptosis. Activated stellate cells play a key role in fibrosis. IL-8, interleukins-8; TNF-α, tumor necrosis factor α; TGF-β, transforming growth factor β.

In a homeostatic setting, apoptosis is accompanied by activation of phagocytosis, leading to efficient removal of cellular corpses without damage to healthy cells (10). However, apoptosis, if massive or simultaneous, results in liver injury. For example, in the setting of massive apoptosis, such as fulminant hepatic failure (FHF), successful hepatocyte repopulation leads to recovery (11). In such an environment, if hepatocyte repopulation is protracted or delayed, liver injury will result. Apoptosis is harmful not only in a passive sense of inadequate repopulation but also as an active inducer of inflammatory processes. In fact, recent data have established a mechanistic link between liver apoptosis, injury, inflammation, and fibrosis in chronic liver disease (12). Apoptotic body engulfment by phagocytic cells leads to their activation. This results in chemokine secretion, recruitment of leukocytes and inflammatory cells to the liver, and amplification of liver injury. HSCs are activated by phagocytosis of apoptotic

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bodies as well, leading to fibrosis (13) (Fig. 10.2).

Death receptors and the liver DRs, transmembrane proteins that belong to the tumor necrosis factor (TNF)/nerve growth factor superfamily, P.315 are essential for ligand–mediated cell death. There are several known death receptors: Fas (CD95/Apo-1), tumor necrosis factor receptor 1 (TNFR1), tumor necrosis factor receptor 2 (TNFR2), tumor necrosis factor–related apoptosisinducing ligand (TRAIL) TRAIL receptor 1 (TRAIL-R1/DR 4), TRAIL receptor 2 (TRAIL-R2/ DR 5/Killer/ TRICK2), DR 3 (DR 3/Apo-3/TRAMP/WSL-1/LARD), and DR 6. Of these receptors, Fas, TNFR1, and TRAIL are thought to be of significance in liver injury. DRs are activated by engagement with their cognate ligands, Fas ligand (FasL), TNF-α, and TRAIL (Figs. 10.3 and 10.4). Interaction P.316 of these ligands with their cognate receptors triggers intracellular signaling pathways. Receptor ligation brings together the intracellular death domains (DDs) that through adaptor proteins (discussed in the following text) lead to the activation of caspase 8 (an initiator caspase). Once activated, caspase 8 cleaves Bid, a cytoplasmic protein. The cleaved protein, tBid, translocates to mitochondria, leading to its release to mitochondrial effectors of apoptosis, ultimately activating caspases 3 and 7 (effector caspases).

▪ Figure 10.3 Fas receptor and associated signaling. The Fas receptor is activated on ligation with Fas ligand (FasL). The ligated receptor forms homotypic trimers, leading to intracellular signaling initiated by their intracellular death domains (DDs). The DDs of trimerized Fas associate with the protein Fas-associated death domain (FADD) through its DD. FADD in turn possesses death effector domains (DEDs) that bind and activate procaspase 8 by proteolytic cleavage. Caspase 8 leads to the cleavage of Bid to tBid, a form that translocates to the mitochondria and causes

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mitochondrial dysfunction. Caspase 10 is also activated by FADD, but its intracellular targets remain undefined. This conglomeration of proteins is known as the Fas death-inducing signaling complex (DISC).

▪ Figure 10.4 Tumor necrosis factor receptor (TNFR1) and associated signaling. Ligation of tumor necrosis factor α (TNF-α) to its receptor TNFR1 initiates two distinct set of signals. The initial signaling pathway involves the proteins TRADD (TNFR-associated protein with death domain), receptorinteracting protein (RIP), and TRAF-2 (TNF-associated factor 2), leading to the activation of nuclear factor κB (NFκB) and c-jun N-terminal kinase (JNK). Following this the receptor undergoes a conformational change, internalization, interaction with FADD, and activation of caspases 8 and 10 with Bid cleavage.

Fas is expressed by every cell type in the liver, including hepatocytes, cholangiocytes, SECs, stellate cells, and Kupffer cells (6,14,15). Activation of Fas, in most instances, requires binding with membrane-bound FasL-expressing cells or soluble FasL. FasL is expressed in cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells. This provides an efficient means of removal of unwanted hepatocytes, such as virus-infected hepatocytes and cancer cells, by T lymphocytes (16,17). Mice genetically deficient in Fas exhibit hepatic hyperplasia, proving a role for Fas in hepatic homeostasis in healthy individuals (18). The multifaceted role of Fas in hepatic homeostasis and injury is introduced in this section and discussed in greater detail in the subsequent sections. Although the significance of Fas in liver disease is undisputed, TNF-α plays a significant, if somewhat complementary, role. There is clear overlap in the

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spectrum of liver injury associated with TNF-α and Fas, with some features unique to TNF-α receptor–mediated signaling. TNFR1 and TNFR2 are both expressed on hepatocytes, although only TNFR1 expresses a DD and executes the apoptotic program. TNFR1 activation leads to both survival and death signals. Immediate recruitment of TNF receptor–associated protein 2 (TRAF-2) and receptor-interacting protein (RIP) to ligated TNFR1 leads to the activation of nuclear factor κB (NFκB) (19). This transcription factor activates a variety of survival genes (e.g., Bcl-XL, A1, XIAP, and cFLIP). Apoptosis is initiated subsequently through the adaptor protein TRADD-mediated caspase 8–Fasassociated death domain (FADD) activation in a receptor-initiated albeit receptorindependent complex (20,21). Therefore, TNFR1 receptor signaling is complex because it usually leads to survival signals but in pathophysiologic states can induce apoptosis. TRAIL and its receptors add further complexity to DRs and their role in the liver. TRAIL receptors 1 and 2 induce apoptosis through caspase activation, similar to Fas (9,22), whereas TRAIL receptors 3 and 4 are thought to function as decoy receptors, interfering with TRAIL-induced death signaling (23). Traditionally, TRAIL has been thought of as being harmless to normal hepatocytes but efficiently apoptotic in solid tumors (24,25,26). Recent experiments have demonstrated a role for TRAIL in murine hepatocyte apoptosis in several models in hepatitis (27,28). Although circulating TRAIL levels are elevated in human viral hepatitis, a conclusive role in mediating apoptosis has not been established (29). Therefore, TRAIL holds the potential for enhancing therapeutic apoptosis of malignant or virally infected cells without collateral damage.

Lysosomes Lysosomes are enzyme-filled, membrane-lined or ganelles that along with peroxisomes form the acid vesicle system. The intraorganelle pH of lysosomes is acidic, and lysosomal enzymes optimally function at this acidic pH. Abnormal lysosomal morphology is found in acute and chronic liver diseases. The accumulation of phospholipids in lysosomes (phospholipidosis) is associated with drug-induced liver injury by amiodarone, trimethoprin–sulfamethoxazole, alcohol, and ketoconazole. Lipid accumulation in lysosomes is also a feature of hepatocyte steatosis. Iron, copper, and lanthane are also lysomotropic and toxic to lysosomes. The extent of release of lysosomal contents (permeabilization) leads to either necrotic cell death, if exuberant, or apoptotic cell death, if the release is controlled. Lysosomal permeabilization may simply involve accumulation of lysomotropic agents with subsequent disruption and release of their content into the cytoplasm. Additionally, reactive oxygen species (ROS), toxic bile salts, sphingosine, free fatty acids (FFAs), ceramide, and TNF-α lead to selective lysosomal permeabilization with subsequent apoptotic cell death. Lysosomal permeabilization leads to the release of lysosomal enzymes into the cytosol, which trigger the mitochondrial pathway of cell death (30,31,32).

Endoplasmic reticulum The ER is a network of intracellular membranes, the largest membranous organelle in a cell. Its primary functions are to synthesize lipids and proteins. Perturbations that interfere with ER function have been collectively called ER stressors. The ER stress pathway is activated by misfolded proteins, glycosylation inhibitors, glucose deprivation, altered glycosylations, ultraviolet (UV) irradiation,

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oxidative stress, and alterations in intracellular calcium level. These stimuli lead to accumulation of abnormal proteins, the so-called unfolded protein response (UPR), which is the hallmark of ER stress (33). Sustained ER stress leads to cell death through at least two well-described mediators. Interactions between regulatory ER-localized kinases (e.g., IRE1, PERK, and ATF6) and downstream effectors lead to activation of c-jun N-terminal kinase (JNK) (34). JNK then activates the mitochondrial pathway of apoptosis (35,36). Another pathway involves the transcription factor CHOP (c/ebp P.317 homologous protein). The downstream effectors of CHOP are not well defined, but the factor regulates apoptosis transcriptionally and nontranscriptionally through protein–protein interactions (37,38). ER stress is best described in α 1 -antitrypsin (α 1 -AT) deficiency in which abnormal protein is aggregated in the ER with resultant downstream death signaling (39).

Oxidative stress Oxygen and oxidative reactions are an essential part of aerobic oxidative phosphorylation, the process that converts nutrient energy into adenosine-5′triphosphate (ATP), the currency of cellular energy. Oxidative stress is a consequence of this aerobic metabolism. The generation of ROS, (e.g., O 2 · - , H 2 O 2 , OH·) and subsequent formation of oxidative products of amino acids, proteins, carbohydrates, lipids, and DNA constitutes oxidative stress. The ROS superoxide (O 2 · - ) also interacts with nitric oxide (NO) to form the reactive nitrogen species, peroxynitrite (ONOO - ). Peroxynitrite is a potent oxidizing and nitrating agent. It can nitrate tyrosine residues in several cellular proteins and iron residues in metalloproteins. Given the dependence on aerobic metabolism for energy, cells harbor several antioxidant defense systems to protect themselves from oxidative and nitrative stress. When antioxidant defense systems are overwhelmed, oxidative and nitrative damage ensues. In acute injury models ROS are associated with mitochondrial permeability transition (MPT) in both apoptotic and necrotic cell death. Lipid peroxidation, oxidized DNA, and nitrated proteins are seen in several models of chronic oxidative stress–inducing liver injury (40,41,42,43). Iron overload, copper overload, chronic ethanol consumption, nonalcoholic steatohepatitis (NASH), and viral hepatitis are all associated with oxidative cellular constituent damage. The importance of oxidative stress is further underscored by the well-established use of the antioxidant Nacetylcyteine in acute acetaminophen-induced liver failure.

Mitochondria Mitochondria are bound by two membranes, the outer and inner mitochondrial membranes. These two membranes enclose the intermembrane space; the inner membrane is folded into cristae and encloses the mitochondrial matrix. Proapoptotic proteins such as cytochrome c, second mitochondrial activator of caspase/direct inhibitors of apoptosis–binding protein with low pI (SMAC/DIABLO), HtrA2/Omi, apoptosis-inducing factor (AIF), and endonuclease G are located within the intermembrane space. The outer mitochondrial membrane is normally impermeable to these proteins, permitting the cell to survive and function. Mitochondrial permeabilization results in the release of these proteins into the cytosol with activation of downstream proteases, culminating in apoptosis (44,45,46) (Fig. 10.5). Mitochondria are essential for the execution of apoptosis in hepatocytes.

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Apoptosis can be divided arbitrarily into three phases, a premitochondrial phase, a mitochondrial phase, and a postmitochondrial phase. The premitochondrial phase is discussed in detail in the section on DRs and other perturbations that culminate in the mitochondria. The end result of the mitochondrial phase is selective mitochondrial permeabilization. This process is regulated by the Bcl-2 family proteins. The Bcl-2 family is divided into pro- and antiapoptotic members. Of the antiapoptotic proteins, Bcl-2, Bcl-XL, and Mcl-1 are important in the liver. The proapoptotic proteins are further divided into multidomain (Bak and Bax) and BH-3 domain only (Bid, Noxa, Puma, Bim, and Bad). Bax is located in healthy individuals in the cytosol but undergoes conformational change and inserts into the mitochondrial membrane to exert its actions. Bak, on the other hand, is an integral mitochondrial protein also activated by conformational change. Bak and Bax then form pores in the outer mitochondrial membrane, leading to permeabilization. The BH-3–only protein Bid is cytosolic and involved in the premitochondrial phase of apoptosis. Its activation is mediated by death receptor–activated caspase 8, and therefore, it serves as a link from the extrinsic to the intrinsic pathway of apoptosis. Bim is activated by its release from cytoskeletal dynein motor complex, and Bad is activated by dephosphorylation. The goal of the proapoptotic members is mitochondrial permeabilization, and the goal of the antiapoptotic members is to prevent just this. The manner in which this occurs is complex and not fully known; it is, however, not just the sum total of the pro- and antiapoptotic signals (47). Mitochondrial abnormalities, both structural and functional, are associated with liver disorders. Drugs and xenobiotics can inhibit the electron transport chain, uncouple oxidative phosphorylation, impair fatty acid oxidation, damage mitochondrial DNA, and impair mitochondrial DNA repair. Mitochondrial abnormalities in alcohol-induced liver disease are well described (42). Ethanoldriven generation of ROS is associated with oxidative damage to lipids, proteins, and DNA. Moreover, high levels of TNF-α expression, driven by ethanol, also lead to an increase in ROS. Ethanol toxicity, therefore, leads to the MPT that may occur either through DR-mediated pathways or through intrinsic cellular stress. Bile acids, whose levels are characteristically elevated in cholestatic liver diseases, can also trigger mitochondrial dysfunction (48,49,50,51). Similarly, mitochondrial dysfunction is associated with NASH, although the molecular mediators need to be defined (52,53,54).

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▪ Figure 10.5 The role of mitochondria in cell death. Mitochondrial dysfunction is an obligate event in hepatocellular apoptosis. Intrinsic apoptotic stimuli such as p53, calcium, oxidative stress, and c-jun Nterminal kinase (JNK), as well as extrinsic apoptotic stimuli (BH-3 proteins), converge on mitochondria. Mitochondrial dysfunction leads to release of several proapoptotic factors. Endonuclease G (Endo G) and apoptosisinducing factor (AIF) lead to deoxyribonucleic acid (DNA) degradation. Second mitochondrial activator of apoptosis (smac) and HtrA inhibit a set of proteins known as inhibitors of apoptosis (IAP) leading to the release of caspases 3 and 9. Cytochrome c complexes with Apaf 1 and adenosine-5′triphosphate (ATP) to form the apoptosome that leads to the activation of caspases 3 and 9 that are released from IAP inhibition.

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Necrosis Necrosis has been defined as an energy-independent process, in which cells swell and lyse, releasing their contents. It has been considered “unprogrammed” compared with apoptosis or programmed cell death. The death signaling in necrosis is considered absent or disordered and the cell death equated to the supernova of cellular death phenomenon. Inflammation is viewed as a consequence of phagocytosis of cellular debris and thought to occur more in necrosis because of exuberant release of cellular contents (Fig. 10.6). Although historically viewed as distinct processes, in the last few years, similarities between the two processes have surfaced. Morphologically, hepatocytes with dual characteristics have been observed in vivo in injury models such as ischemiareperfusion (IR). Regulated, albeit caspase-independent, and death receptor– independent cell death has broadened the definition of necrosis and blurred the erstwhile clear-cut distinction from apoptosis. In addition Fas-mediated necrosis has been described (55). Increasingly, necrosis is viewed as a massive yet programmed cell death (56,57). Cellular ATP depletion activates necrotic cell death. During ischemia a lack of

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oxygen and nutrients leads to a dramatic and absolute inability to generate ATP. This activates processes leading to cellular destruction and necrosis. Exposure to massive ischemia, nitrative/oxidative stress, and xenobiotics can all result in hepatic necrosis (43,58). In some instances the magnitude of noxious stimulus controls the subsequent mode of cell death, with apoptosis resulting from a lesser stimulus and necrosis occurring with the greater magnitude of hepatic insult.

Mitochondria in necrosis In addition to their role in apoptosis, mitochondria mediate necrotic cell death (Fig. 10.7). MPT, an abrupt increase in the permeability of the inner and outer mitochondrial membranes, occurs in necrosis. This is mediated by the MPT pore, (permeability transition pore [PTP]). The PTP is formed by voltage-dependent anion channel (VDAC) on the outer membrane and adenine nucleotide transporter (ANT) on the inner membrane along with cyclophilin D. The permeability transition leads to dissipation of the electrochemical gradient across the inner mitochondrial membrane, uncoupling of oxidative phosphorylation, and an inability to synthesize new ATP. Calcium and mitochondrial proteins are released as well. Mitochondrial swelling occurs secondary to an increase in membrane permeability, leading to mitochondrial rupture and necrotic cell death (59).

▪ Figure 10.6 Apoptosis and necrosis are divergent endpoints of common initiating signals. Death-initiating signals lead to activation of early apoptotic signals. In the milieu of adenosine triphosphate (ATP) depletion, loss of ion gradients and cellular swelling ensues. This results in mitochondrial and cellular rupture with release of intracellular content. In a controlled and energy-replete environment, the apoptotic cascade proceeds, leading to nuclear condensation and fragmentation of cells into apoptotic bodies. Physiologically, these apoptotic bodies are engulfed and efficiently removed by Kupffer cells.

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Disease Mechanisms Alcohol-Related Liver Disease Alcoholic steatohepatitis (ASH) is characterized by steatosis, hepatocyte apoptosis, and acute inflammation. The cellular mechanisms and cytokine milieu leading to alcohol-induced liver injury are well defined. The factors that impart each individual's susceptibility to liver damage are less well understood. In experimental models, ethanol induces changes in mitochondrial and microsomal function with subsequent apoptosis and necrosis (60). Oxidative stress occurs with acute and chronic ethanol ingestion. MPT occurs as a result of oxidative stress, leading to the release of cytochrome c and other mitochondrial enzymes, P.320 activation of effector caspases, and apoptosis (61,62). Neutralization of ROS with antioxidants, inhibition of MPT, or inhibition of caspases prevents acute ethanolinduced apoptosis. Oxidative stress also leads to translocation of Bax from cytosol to mitochondria, resulting in mitochondrial dysfunction (63). Induction of cytochrome P-450 2E1 (CYP2E1), a well-known effect of ethanol ingestion, also promotes generation of ROS and may explain how ethanol induces its own toxicity in a feedback loop (60,64). Kupffer cells demonstrate increased expression of CYP2E1 and oxidative stress, and more importantly, they become activated in acute alcohol-mediated liver injury. Once activated, they secrete a number of cytokines, including TNF-α, IL-6, and transforming growth factor β 1 (TGF-β 1 ) (65,66,67). The role of these inflammatory cytokines is underscored by studies using endotoxinemia to promote TNF-α expression and liver injury and, on the other hand, selective gut decontamination (with antibiotics to reduce portal vein endotoxin levels) with attenuation of both TNF-α signaling and liver injury (65,68). Furthermore, genetic studies in mice demonstrated that TNFR1 is essential for alcohol-induced liver injury (69).

▪ Figure 10.7 The mitochondrial permeability transition (MPT) pore.

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Mitochondria mediate necrotic cell death in the liver. The mitochondrial permeability transition pore (PTP) is formed by voltage-dependent anion channel (VDAC) on the outer membrane and adenine nucleotide transporter (ANT) on the inner membrane along with cyclophilin D. Opening of the PTP leads to mitochondrial swelling, rupture, and release of intermembrane proteins.

Apoptosis occurs in patients with ASH and is correlated with bilirubin, aspartate aminotransferase (AST), and grade 4 steatohepatitis (70,71,72). Hepatic Fas receptor expression is enhanced in ASH, compared with normal livers (70). Studies on sera of patients with ASH have shown increased circulating levels of Fas, FasL, and TNF-α. TNF-α levels correlate with mortality in these patients (73,74,75,76). Hepatocyte apoptosis also correlates with Maddrey's score, a prognostic indicator in acute alcoholic hepatitis. The characteristic inflammatory response occurs secondary to hepatocyte apoptosis and also because of the direct effects of ethanol on Kupffer cells, leading to cytokine production (66). In summary, alcohol-induced liver injury occurs in the setting of oxidative stress and a proinflammatory cytokine environment that together induce hepatocyte apoptosis and consequent inflammation. Apoptosis correlates with the severity of liver injury. Inhibition of the apoptotic signaling pathway holds the potential for future therapies of alcoholic liver disease.

Nonalcoholic Steatohepatitis Nonalcoholic fatty liver disease (NAFLD), the hepatic component of the metabolic syndrome, has become the most common liver disorder in the United States (77). Hepatocyte apoptosis is a prominent feature of NASH and correlates with disease severity, disease progression, and fibrosis (78). This association underscores the importance of hepatocyte apoptosis and raises the question why only certain steatotic cells die. Recent mechanistic understanding of hepatocyte apoptosis in NASH have elucidated the role of DR ligands, circulating and intrahepatic FFAs, inflammatory cytokines, mitochondrial abnormalities, and genes of fat regulation (53,78,79). Early pathogenetic studies have described increased Fas and TNFR1 expression in livers of patients with NASH (1). Furthermore, circulating TNF-α levels are also elevated in patients with NASH. This is confirmed by studies in animal models of steatosis, in which apoptosis and inflammation are enhanced after administration of DR ligands, Fas, and TNF-α (80). These data demonstrate the sensitivity of the steatotic hepatocyte to a secondary insult. Insulin resistance, a feature of obesity and the metabolic syndrome, leads to elevated plasma FFA levels. Recent advances have been made in elucidating the cellular mechanisms by which FFA leads to apoptosis in the steatotic hepatocyte, a process termed lipoapoptosis. At least two mechanisms have been described. Lysosomal permeabilization by FFA in an in vitro model using HepG2 cells has partially elucidated the role of the intrinsic apoptotic pathway. Indeed, this has been confirmed in patients with NASH who show evidence of lysosomal permeabilization and release of cathepsin B (79). Furthermore, TNF-α expression occurs downstream of, and is partially dependent on, lysosomal permeabilization in this model. A separate in vitro study of the sensitivity of steatotic HepG2 cells to Fas ligand, presumably through upregulation of Fas receptor, provides another piece of the puzzle that integrates

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the well-characterized death ligand sensitivity of steatotic livers with the primary metabolic abnormality observed in this syndrome (80). Mitochondria are central to cell death, and FFA-mediated mitochondrial dysfunction in HepG2 cells, as well as primary mouse hepatocytes, has been described as well. One way in which mitochondrial dysfunction can be activated is by a family of signaling enzymes, the mitogen-activated protein kinases (MAPKs). FFA-induced activation of c-JNK, a proapoptotic MAPK, with subsequent JNK-dependent apoptosis in hepatocytes is also an important pathway of FFA-induced lipoapoptosis. Mitochondrial dysfunction in this model results from upregulation of proapoptotic Bcl-2 family proteins (Malhi H, Gores GJ, unpublished observations, 2006). Abnormal mitochondrial structure and function also occur in patients with NASH (53). Megamitochondria with crystalline inclusions, decreased hepatic mitochondrial DNA content, and decreased respiratory chain function occur. CYP2E1 level is increased in patients with NASH, and there is some evidence for increased oxidative stress, which may be stimulated by enhanced FFA-driven mitochondrial β-oxidation. Therefore, the role of mitochondrial abnormalities and oxidative stress as activators of the intrinsic pathway of apoptosis needs to be studied further. P.321

Viral Hepatitis Hepatitis B virus (HBV) and hepatitis C virus (HCV) cause both acute and chronic hepatocellular infection. In acute viral infection, immune-mediated apoptosis leads to elimination of infected cells, and for chronic infection to be successful, virally infected hepatocytes must evade apoptosis (81). The cell injury in acute infection occurs in two phases. The first phase in acute HBV and HCV infection involves CTL-induced Fas-mediated hepatocyte apoptosis (82,83). The second wave of injury is triggered by apoptosis and occurs as a nonspecific necroinflammatory response that also damages bystander cells that do not express viral antigens (84,85). Also, the virus has a small direct cytopathic effect. In chronic infection there is ongoing, low-grade, Fas-mediated apoptosis. Apoptosis correlates with histologic severity of chronic hepatitis (86). In sera from patients with chronic HBV and HCV infection sFas levels are increased and correlate with alanine aminotransferase (ALT) levels, histology, and response to therapy (87,88). Furthermore, at the onset of treatment with interferon, sFas levels increase in parallel with ALT values, suggesting enhanced Fas-mediated immune clearance of infected cells (89). Active alcohol consumption in hepatitis C leads to a significant increase in hepatocyte apoptosis that correlates with increased Fas levels, pointing toward a convergence of two distinct apoptotic stimuli on the Fas signaling pathway (90). Not only is there evidence of apoptosis but also soluble markers of apoptosis hold the promise of surrogacy, decreasing the need for repeated liver biopsies (91). It is also clear from several experimental models that HCV proteins regulate apoptosis (92). HCV core protein confers sensitivity to TRAIL-mediated apoptosis in cells previously resistant to its effect (93). Other HCV proteins such as NS3 can activate caspase 8–mediated apoptosis, independent of Fas (94). The inhibition of apoptosis of virally infected hepatocytes possibly provides a mechanism for both viral persistence and development of hepatocellular carcinoma (HCC). Indeed, in a mouse model of hepatic carcinogenesis, the introduction of core E1 and E2 proteins lead to the formation of larger tumors (95,96,97,98,99). In complementary in vitro

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experiments, HCV core protein inhibited Fas- and TNF-α-mediated apoptosis in HepG2 cells (100). Similarly, in chronic HBV infection both Fas receptor and TNFR1 expression are increased in hepatocytes (101). Levels of circulating Fas and TNF-α are increased as well and correlate with severity of infection (88,102). HBV X protein (Hbx) has complex biologic functions in the host, which remain controversial and are reported to attenuate and promote cell death (103,104,105,106,107,108). Therefore, both HCV and HBV infection, although cleared by immune-mediated hepatocyte apoptosis, regulate the apoptotic machinery to establish chronic infections predisposing to hepatocarcinogenesis.

Ischemia-Reperfusion Injury IR injury occurs during liver transplantation, liver surgery, and hypotensive states. Hemodynamic changes are an integral part of liver transplantation surgery, therefore, understanding the mechanisms of cold ischemia (CI)/warm reperfusion (WR) injury should promote therapeutic strategies to minimize injury and improve allograft function. WR occurs in other forms of liver surgery and hypotensive states. SECs are the immediate target of CI/WR injury, with hepatocyte injury occurring after prolonged periods of ischemia. In contrast, hepatocytes are the primary target in WR injury. Cold storage alone leads to apoptosis of SEC. Use of caspase inhibitors significantly decreases SEC apoptosis and improves survival after orthotopic liver transplantation (OLT) (109). Kupffer cells are activated and secrete numerous cytokines that in turn activate apoptosis and attract inflammatory cells. Depletion of Kupffer cells using gadolinium chloride decreases SEC apoptosis and liver injury in CI/WR (110,111). IR injury involves hepatocyte apoptosis, which also correlates with the duration of ischemia and the presence of preexisting liver damage (112). Activation of NFκB, TNF-α, and Fas modulate IR-induced hepatocyte apoptosis (113,114). NFκB has a biphasic activation after IR; the initial phase promotes expression of TNF-α, leading to apoptosis and inflammation, and the later phase is protective, such that selective inhibition of activation of the later phase enhances liver injury, and nonspecific inhibition attenuates injury (115). Historically, necrosis and apoptosis both have been thought to mediate IR injury; recent evidence, however, points toward apoptosis as the principal mode of hepatocyte cell death in IR (58,116). In experimental models TNF-α-dependent apoptosis, capsase-dependent hepatocyte apoptosis, and increase in levels of FasL expression were observed (113,117). Stress-activated protein kinases, such as JNK, are also activated soon after OLT (118). Use of JNK inhibitors preserves hepatic architecture and attenuates injury (119). Expression of Bcl-2, an antiapoptotic protein, by several different modalities, protects hepatocytes against ischemic apoptosis and liver injury (120). The use of small interfering ribonucleic acid (siRNA) to decrease the expression of caspases 8 and 3 also reduces IR injury. In summary, IR injury is mediated by apoptosis of both parenchymal and nonparenchymal liver cells. Inhibition of apoptosis in experimental studies has improved the outcomes of OLT; this offers promising interventions to maximize allograft function. P.322

Cholestatic Injury Cholestasis, an impairment in bile flow and/or secretion, is characterized by an increase in hepatocellular bile acid concentrations. At a cellular level, the effects of hydrophobic bile acids are well understood. Glycine-conjugated

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chenodeoxycholic acid (GCDC) is more toxic than taurine-conjugated chenodeoxycholic acid (TCDC) (121,122). Toxic bile acids induce hepatocyte apoptosis in vitro and also in vivo in animal models of extrahepatic cholestasis (bile duct–ligated animal). There is evidence of involvement of the death ligands, Fas and TRAIL, in bile acid–mediated apoptosis (123,124). The importance of Fas receptor in this pathway is proved further by studies in mice deficient in Fas receptor (lpr). Following bile duct ligation in these lpr mice, hepatocyte apoptosis is attenuated (125). Furthermore, in long-term follow-up in these animals, fibrosis is attenuated as well. This study underscores the importance of the paradigm that hepatocyte apoptosis acts as a fibrogenic stimulus, resulting ultimately in liver cirrhosis. Fas-induced apoptosis is not the only mechanism of hydrophobic bile acid toxicity. In cholestatic lpr mice, hepatocyte apoptosis eventually occurs, although delayed and attenuated when compared to wild type mice. Bax levels and translocation to mitochondria are increased in cholestatic lpr mice and explains the onset of apoptosis (5). Inhibition of apoptosis by inhibiting Bid prevents both Fas-dependent and Fas-independent bile acid–induced hepatocyte apoptosis (126). Furthermore, in Fas-deficient cells, the role of TRAIL-R2 in bile acid– induced hepatocyte apoptosis has been unmasked. TRAIL activation by GCDC leads to the recruitment of the classical TRAIL–death-inducing signaling complex (DISC), with activation of caspases 8 and 10, involvement of mitochondria, release of cytochrome c, and apoptosis (49). Primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC) are the two commonest etiologies of adult intrahepatic cholestasis. Immune-mediated apoptosis of biliary epithelial cells (BECs) is well defined in PBC (127,128). Pyruvate dehydrogenase complex (PDC), a mitochondrial protein, is expressed on the cell surface membrane of BEC in PBC. Autoantibodies and autoreactive T cells exist against this antigen, perpetuating immune-mediated BEC apoptosis. PDC is normally sequestered in the inner mitochondrial membrane. Although the perpetuation of autoimmune injury in response to PDC is understood, the initial apoptotic stimulus that leads to mitochondrial dysfunction and expression of PDC on BEC surface is unknown. In experimental models it was found that immunoreactive PDC migrated from the mitochondria to the plasma membrane of cells after the induction of apoptosis (3). Therefore, apoptosis plays a role in bile duct injury and in the ensuing hepatocellular injury seen in cholestasis.

Wilson Disease and Hemochromatosis Wilson disease is characterized by a hepatocellular defect resulting from mutations in a copper-transporting P-type ATPase (ATP7B) with an inability to excrete copper in bile. This leads to copper accumulation in hepatocytes, which is cytotoxic (129). The Long-Evans Cinnamon (LEC) rat is a spontaneous mutant that mimics human Wilson disease (130). This animal shows evidence of chronic oxidative damage, such as lipid peroxidation and DNA strand breaks (131,132). This suggests a role for oxidative stress because copper has redox activity, such as the Fenton and Haber-Weiss reactions, leading to the generation of free radicals and oxidative damage to lipids, proteins, and DNA. In vitro data shows that copper overload also leads to p53-dependent cell death (133). The course of Wilson disease in humans runs the gamut from FHF to mild chronic hepatitis. In patients with Wilson disease who have FHF, high levels of apoptosis, Fas receptor, and Fas messenger RNA (mRNA) were detected (134). Oxidatively damaged and bulky DNA, indicative of damaged DNA with adduct formation, was

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detected in patients with Wilson disease (40,135). Therefore, copper overload causes apoptotic hepatocellular death in patients with Wilson disease. Oxidative stress is a direct consequence of iron overload because of the redox activity of iron and the generation of oxygen free radicals. As with copper excess, the generation of ROS occurs through Fenton and Haber-Weiss reactions. Oxidative damage to all cellular constituents ensues and, indeed, oxidative DNA adducts are found in patients with hereditary hemochromatosis (41). Although iron is not a direct carcinogen, iron overload is associated with increased risk for the development of HCC (136).

α 1 -Antitrypsin Deficiency

α 1 -AT is normally secreted predominantly by hepatocytes. Patients with α 1 -AT deficiency produce an abnormal variant of the protein, resulting in a failure of hepatocytes to secrete it into the serum. This leads to accumulation of the abnormal protein within hepatocytes. The normal homeostatic response leads to enhanced degradation of the abnormal protein, but in individuals unable to breakdown the accumulated protein, hepatocyte injury ensues. The ER is a major site of degradation of abnormal proteins in the body. Briefly, the accumulation of abnormal α 1 -AT in the ER leads to P.323 activation of autophagic processes. Mitochondrial dysfunction and caspase 3 activation occur downstream of this ER stress response (39). The molecular pathways that mediate α 1 -AT-induced ER stress and mitochondrial dysfunction are not well defined and are an area for future research.

Fulminant Hepatic Failure Several lines of experimental data and human observations point to the importance of DR-mediated apoptosis in FHF. In a seminal paper Lacronique et al. (137) it was reported that induced massive hepatocyte apoptosis and FHF in mice using an anti-Fas antibody activated the death signaling cascade and rescued livers from apoptosis and animals from death by increasing the expression of antiapoptotic Bcl-2 (137,138). In patients with FHF, levels of both Fas receptor and Fas ligand expression in hepatocytes are high. Fas ligand levels are elevated in infiltrating lymphocytes, circulating lymphocytes, and sera of patients as well. Hepatocyte apoptosis in addition to enhanced Fas expression has been observed in FHF of different etiologies (134,139,140). In addition to Fas, circulating levels of TNF-α and TNF-α receptors are increased in patients with FHF and correlate with the recovery of native liver function (141). Besides activation of NFκB to aid in recovery, the dichotomous role of TNF-α is further developed in FHF, in which it increases the expression of FADD protein, perhaps augmenting Fas sensitivity. In summary, FHF is accompanied by several cytokine changes, of which Fas clearly mediates apoptosis. TNF-α and other cytokines serve dichotomous roles, promoting apoptosis, inflammation, and recovery. Enhancing the milieu in favor of recovery by inhibiting Fas-mediated apoptosis appears to be a promising therapeutic strategy, one that should be developed further with human clinical trials, given the shortage of donor organs.

Therapeutic Implications Understanding apoptotic cascades in liver disease has unraveled novel therapeutic opportunities (Fig. 10.8). Neutralization of TNF-α in treatment of alcoholic hepatitis has shown early promise (142,143). Ribonucleic acid

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interference (RNAi) therapy selectively manipulates a cell's genetic machinery to reduce expression of the protein of interest. Disruption of Fas and caspase 8 gene expression, using RNAi, ameliorated injury and improved survival in experimental FHF and immune-mediated hepatitis (140,144). Increased expression of antiapoptotic Bcl-2 and caspase inhibition protected against FHF (137,145). Similarly, targeted hepatic delivery of NCX-1000, a NO conjugate of urosdeoxycholic acid (UDCA), that selectively releases NO in the liver even after onset of apoptosis protects from acetaminophen (N-acetyl-p-aminophenol [APAP])-induced FHF (146). In a model of IR injury, silencing initiator and effector caspases had a salutary effect on the liver (116). UDCA has a dual effect of preventing mitochondrial permeabilization and apoptosis induced by bile acid, ethanol, Fas, and TGF-β 1 (147) and also promoting the activation of survival signals in cells (148). Furthermore, in animal studies an antiapoptotic molecule, IDN-6556 (a pan-caspase inhibitor), reduces cholestatic hepatocyte apoptosis, stellate cell activation, liver injury, and resultant fibrosis (149). At a mitochondrial level, the disruption of proapoptotic Bcl-2 family proteins also prevents bile acid–induced apoptosis (126).

▪ Figure 10.8 Therapeutic targets in apoptosis. Schematic representation of

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potential therapeutic targets in liver diseases. Apoptosis can be inhibited at several levels. Death receptor and ligand interaction can be prevented by neutralizing antibodies. Pharmacologic inhibitors, small interfering ribonucleic acid (siRNA), antisense molecules, modulation of Bcl-2 family pro- and antiapoptotic proteins with nuclear receptor agonists, for example, constitutive androstane receptor (CAR), are all potential therapeutic strategies. Ursodeoxycholic acid (UDCA) has been in clinical use for cholestatic liver disease.

P.324 The fact that apoptosis can be modulated temporally after cells have been exposed to apoptotic stimuli is appealing in its applicability to the clinical scenario. Indeed, several studies in experimental models of acute and chronic liver disease have demonstrated amelioration of liver apoptosis and injury and improved survival, with inhibition of apoptosis even after exposure to the apoptogenic stimulus. Future studies should be directed toward development of rational antiapoptotic therapies targeted to the liver.

Acknowledgments This work was supported by NIH grant DK 41876 and the Mayo and Palumbo Foundations. The authors acknowledge the superb secretarial assistance of Erin Bungum.

Annotated References Canbay A, Higuchi H, Bronk SF, et al. Fas enhances fibrogenesis in the bile duct ligated mouse: a link between apoptosis and fibrosis. Gastroenterologia 2002;123:1323–1330. This article is important because it highlights the principle that sustained hepatic injury leads to sustained hepatocyte apoptosis and attendant fibrosis. Interruption of this process prevents apoptosis and mechanistically links two important observations, that is, apoptosis and fibrosis. Edinger AL, Thompson CB. Death by design: apoptosis, necrosis and autophagy. Curr Opin Cell Biol 2004;16:663–669. Apoptosis and necrosis have classically been viewed as different modes of cell death, with opposite physiologic and pathologic effects. This article explores the gray areas in this erstwhile black or white delineation. Guicciardi ME, Gores GJ. The death receptor family and the extrinsic pathway. In: Yin X-M, Dong Z, eds. Essentials of apoptosis: a guide for basic and clinical research. Totowa: Humana Press Inc, 2003:67–84. This is a comprehensive review of death receptors and their signaling pathways. It is essential reading for anyone wishing to understand death receptor–mediated signals.

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Martinou JC, Green DR. Breaking the mitochondrial barrier. Nat Rev Mol Cell Biol 2001;2:63–67. Mitochondria are essential to cell death. Mitochondrial contents need to be released into the cytoplasm for cell death to proceed. This review describes essential concepts in mitochondrial permeabilization. Ribeiro PS, Cortez-Pinto H, Sola S, et al. Hepatocyte apoptosis, expression of DRs, and activation of NF-kappaB in the liver of nonalcoholic and alcoholic steatohepatitis patients. Am J Gastroenterol 2004;99:1708–1717. The importance of apoptosis, death receptor signaling, and activation of inflammatory pathways in two common and relevant liver diseases are described.

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111. Arii S, Imamura M. Physiological role of sinusoidal endothelial cells and Kupffer' cells and their implication in the pathogenesis of liver injury. J Hepatobiliary Pancreat Surg 2000;7:40–48.

112. Kohli V, Selzner M, Madden JF, et al. Endothelial cell and hepatocyte deaths occur by apoptosis after ischemia-reperfusion injury in the rat liver. Transplantation 1999;67:1099–1105.

113. Rudiger HA, Clavien PA. Tumor necrosis factor alpha, but not Fas, mediates hepatocellular apoptosis in the murine ischemic liver. Gastroenterologia 2002;122:202–210.

114. Li SQ, Liang LJ, Huang JF, et al. Hepatocyte apoptosis induced by hepatic ischemia-reperfusion injury in cirrhotic rats. Hepatobiliary Pancreat Dis Int 2003;2:102–105.

115. Takahashi Y, Ganster RW, Gambotto A, et al. Role of NF-kappaB on liver cold ischemia-reperfusion injury. Am J Physiol Gastrointest Liver Physiol 2002;283:G1175–G1184.

116. Contreras JL, Vilatoba M, Eckstein C, et al. Caspase-8 and caspase-3 small interfering RNA decreases ischemia/reperfusion injury to the liver in mice. Surgery 2004;136:390–400.

117. Cursio R, Filippa N, Miele C, et al. Fas ligand expression following normothermic liver ischemia-reperfusion. J Surg Res 2005;125:30–36.

118. Bradham CA, Stachlewitz RF, Gao W, et al. Reperfusion after liver transplantation in rats differentially activates the mitogen-activated protein kinases. Hepatology 1997;25:1128–1135.

119. Uehara T, Xi Peng X, Bennett B, et al. c-Jun N-terminal kinase mediates hepatic injury after rat liver transplantation. Transplantation 2004;78:324– 332.

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120. Bilbao G, Contreras JL, Eckhoff DE, et al. Reduction of ischemiareperfusion injury of the liver by in vivo adenovirus-mediated gene transfer of the antiapoptotic Bcl-2 gene. Ann Surg 1999;230:185–193.

121. Torchia EC, Stolz A, Agellon LB. Differential modulation of cellular death and survival pathways by conjugated bile acids. BMC Biochem 2001;2:11.

122. Rust C, Karnitz LM, Paya CV, et al. The bile acid taurochenodeoxycholate activates a phosphatidylinositol 3-kinase-dependent survival signaling cascade. J Biol Chem 2000;275:20210–20216.

123. Faubion WA, Guicciardi ME, Miyoshi H, et al. Toxic bile salts induce rodent hepatocyte apoptosis via direct activation of Fas. J Clin Invest 1999;103:137–145.

124. Higuchi H, Yoon JH, Grambihler A, et al. Bile acids stimulate cFLIP phosphorylation enhancing TRAIL-mediated apoptosis. J Biol Chem 2003;278:454–461.

125. Canbay A, Higuchi H, Bronk SF, et al. Fas enhances fibrogenesis in the bile duct ligated mouse: a link between apoptosis and fibrosis. Gastroenterologia 2002;123:1323–1330.

126. Higuchi H, Miyoshi H, Bronk SF, et al. Bid antisense attenuates bile acidinduced apoptosis and cholestatic liver injury. J Pharmacol Exp Ther 2001;299:866–873.

127. Tinmouth J, Lee M, Wanless IR, et al. Apoptosis of biliary epithelial cells in primary biliary cirrhosis and primary sclerosing cholangitis. Liver 2002;22:228–234.

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131. Yamamoto H, Hirose K, Hayasaki Y, et al. Mechanism of enhanced lipid peroxidation in the liver of Long-Evans cinnamon (LEC) rats. Arch Toxicol 1999;73:457–464.

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133. Narayanan VS, Fitch CA, Levenson CW. Tumor suppressor protein p53 mRNA and subcellular localization are altered by changes in cellular copper in human Hep G2 cells. J Nutr 2001;131:1427–1432.

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135. Carmichael PL, Hewer A, Osborne MR, et al. Detection of bulky DNA lesions in the liver of patients with Wilson's disease and primary haemochromatosis. Mutat Res 1995;326:235–243.

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149. Canbay A, Feldstein A, Baskin-Bey E, et al. The caspase inhibitor IDN6556 attenuates hepatic injury and fibrosis in the bile duct ligated mouse. J Pharmacol Exp Ther 2004;308:1191–1196.

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Copyright ©2007 Lippincott Williams & Wilkins > Table of Contents > Volume I > Sect ion II - General Considera tions > Chapt er 11 - The Liver in Systemic Disease

Chapter 11 The Liver in Systemic Disease Lawrence S. Friedman Andrew S. Ross

Key Concepts z

Liver disease is highly prevalent in patients with type 2 diabetes mellitus and can range from mild steatosis to cirrhosis and hepatocellular carcinoma. The impact of liver disease on mortality in patients with diabetes is substantial.

z

Patients with thyroid disorders, especially hyperthyroidism, commonly have abnormal liver chemistries. Thyrotoxicosis can lead to ischemic hepatic injury, whereas hepatic dysfunction in myxedema may result from right-sided heart failure. Medications used to treat hyperthyroidism can lead to hepatotoxicity.

z

Celiac disease may account for otherwise unexplained liver chemistry abnormalities in a substantial number of affected persons.

z

Liver disease associated with various rheumatic disorders is commonly the result of the medications used to treat these conditions.

z

Liver dysfunction in patients with sickle cell disease results from red cell sickling within hepatic sinusoids and must be distinguished from cholecystitis and choledocholithiasis.

z

Hepatic involvement is common in amyloidosis and sarcoidosis. In amyloidosis, hepatic involvement rarely causes clinical manifestations but indicates an ominous prognosis. Hepatic sarcoidosis may occasionally be complicated by cirrhosis and portal hypertension.

z

Involvement of the liver by lymphoma is more common in patients with non-Hodgkin's lymphoma than in those with Hodgkin's disease. Rarely, hepatic lymphoma can result in acute liver failure.

The liver interacts in multiple ways with other organ systems and is often involved by systemic disease processes. This chapter reviews the systemic disorders that most frequently involve the liver and includes only those diseases that are not covered in detail in other chapters.

Endocrine Disorders Diabetes Mellitus Approximately 17 million people in the United States are affected by type 2 diabetes mellitus, and liver disease is one of the leading causes of death in this patient population (1,2). In fact, the standardized mortality rate for liver disease among patients with type 2 diabetes mellitus is higher than that for cardiovascular disease. Liver disease in patients with type 2 diabetes mellitus can range from nonalcoholic fatty liver disease (NAFLD) to cirrhosis and hepatocellular carcinoma (HCC) (1,3). In addition, evidence suggests that the frequency of chronic hepatitis C is increased among patients with type 2 diabetes mellitus (4). The most common liver disease associated with diabetes mellitus is NAFLD (1,5,6) (see Chapter 39). It has been estimated that up to 70% of patients with type 2 diabetes mellitus have some form of NAFLD, P.330 and this rate may reach 100% in patients with both diabetes and obesity (7). Nonalcoholic steatohepatitis (NASH) is almost three times as frequent in persons with type 2 diabetes mellitus as in persons without type 2 diabetes mellitus and is estimated to be present in up to 50% of patients with type 2 diabetes mellitus and NAFLD. Even more alarming is the fact that up to 19% of patients with type 2 diabetes mellitus and NAFLD have cirrhosis (1). Patients with diabetes and NAFLD typically present with asymptomatic elevations in serum aminotransferase levels; massive hepatomegaly has been described in rare cases. Mild elevations in serum alkaline phosphatase and γ-glutamyl transpeptidase levels have also been described. Fatty infiltration of the liver in patients with type 2 diabetes mellitus is typically diffuse (Fig. 11.1), although fat accumulation may be focal (1). Steatosis can generally be diagnosed by abdominal ultrasonography, which reveals a diffuse increase in hepatic echogenicity, with focal areas of fat sparing that appear as mass lesions (1,8). Although magnetic resonance spectroscopy can quantify hepatic steatosis, liver biopsy is

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required for the detection of NASH and fibrosis. In addition to steatosis, liver biopsy findings in patients with NASH include various combinations of inflammation, Mallory's hyaline, balloon degeneration of hepatocytes, and fibrosis. Nuclear glycogenation, producing a vacuolated appearance of hepatocyte nuclei on light microscopy, may be found in up to 75% of patients with type 2 diabetes mellitus. This feature is not pathognomonic of diabetes and may also occur with bacterial inflammation, tuberculosis, cirrhosis, hepatitis, and Wilson disease, and even in normal livers (1).

▪ Figure 11.1 Liver biopsy specimen demonstrating severe steatosis in a patient with diabetes mellitus and obesity (hematoxylin and eosin). (Courtesy of John Hart, MD, Chicago, IL: Department of Pathology, University of Chicago Pritzker School of Medicine.)

Insulin resistance and obesity appear to be the common factors that link NAFLD to diabetes mellitus (7,9,10) (Fig. 11.2). The resistance to insulin that characterizes type 2 diabetes mellitus leads to decreased peripheral glucose uptake and enhanced adipocyte lipolysis, in turn leading to increased insulin resistance and further deposition of fat in the liver. The biochemical basis of hepatic lipid deposition in patients with type 2 diabetes mellitus remains to be elucidated. One theory postulates that high circulating levels of insulin lead to defective fatty acid oxidation in the mitochondria, thereby resulting in the intracytoplasmic accumulation of triglycerides within the hepatocytes. An inflammatory response may ensue and result in NASH and, in some cases, hepatic fibrosis and, ultimately, cirrhosis (1). As compared with patients without diabetes who have steatosis, patients with type 2 diabetes mellitus having steatosis may be at increased risk for NASH, likely because of the persistence of insulin resistance (1). The cornerstones of management of patients with diabetes mellitus and hepatic steatosis are metabolic control and weight loss. Although weight loss is clearly important, the ideal rate of weight reduction in patients with hepatic steatosis is debated. Rapid weight reduction can lead to increased formation and hepatic deposition of free fatty acids. The use of pharmacologic agents to reduce steatosis has been investigated (11). Medications such as pioglitazone, rosiglitazone, and metformin that reduce insulin resistance have been shown to improve liver histopathology, hepatic lipid content, and liver biochemical test results in patients with hepatic steatosis and NASH (12,13,14). Although promising, the use of these agents to treat hepatic steatosis and NASH remains investigational.

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▪ Figure 11.2 Metabolic effects of insulin resistance in skeletal muscle, fat, and liver. The resistance to insulin leads to decreased peripheral glucose uptake and enhanced adipocyte lipolysis, in turn leading to increased insulin resistance and further hepatic fat deposition. FFA, free fatty acid; VLDL, very low density lipoprotein. (From Tolman KG, Fonseca V, Tan MH, et al. Narrative review: hepatobiliary disease in type 2 diabetes mellitus. Ann Intern Med 2004;141:946–956. Reprinted with permission.)

P.331 In addition to the increased frequency of NAFLD in patients with diabetes mellitus, several epidemiologic studies have suggested that the risk of HCC is increased in patients with diabetes mellitus (1,15,16,17,18,19,20,21,22). Studies from Europe and the United States suggest that the risk of HCC may be increased up to fourfold in patients with diabetes mellitus as compared with subjects without diabetes (16,17,18,19,20,21,22). This risk persists even when patients with viral hepatitis are excluded from analysis, thereby suggesting that diabetes may be an independent risk factor for the development of HCC. Cirrhosis resulting from progressive NASH likely provides the background for the development of HCC among patients with type 2 diabetes mellitus. A proposed mechanism of carcinogenesis in this setting includes the formation of reactive oxygen species in hepatocytes as a result of insulin resistance, enhanced lipolysis, and lipid accumulation within hepatocytes (1). Data from several epidemiologic studies suggest that the frequency of hepatitis C virus (HCV) infection is higher in patients with diabetes mellitus than in the general population, and some evidence even suggests that HCV may have a causative role in the development of diabetes (1,23,24,25,26,27) (see Chapter 30). Several studies have demonstrated a higher frequency of diabetes among patients with HCV infection than among those infected with hepatitis B virus (HBV). In addition, patients infected with HCV who have undergone liver transplantation have a higher frequency of diabetes than do patients who have undergone transplantation for other diseases. Finally, glucose intolerance improves after eradication of HCV with interferon-based therapy. Together, these data suggest that HCV plays a role in the pathogenesis of diabetes. Although HCV genotype 1 is the most common genotype in patients with type 2 diabetes mellitus and HCV infection, the frequency of HCV genotype 2 is disproportionately represented among patients with type 2 diabetes mellitus and HCV infection as compared with those without diabetes (1). The presence of fatty liver is actually highest among patients infected with HCV genotype 3; treatment with interferon-based therapy has been found to reduce the P.332 degree of steatosis in this population (1). Patients with HCV infection and fatty liver are less likely to respond to antiviral therapy than are those without fatty liver (1). Patients with diabetes have a two- to threefold increased frequency of cholelithiasis as compared with persons without diabetes. Although comorbid obesity may be a contributing pathogenic factor, diabetes alone has been found to be an independent risk factor for the development of gallstones. The mechanism remains speculative, although sluggish bile flow, perhaps caused by diabetic autonomic neuropathy, has been proposed (1,28). A noncirrhotic form of hepatic sinusoidal fibrosis, termed diabetic hepatosclerosis and attributed to microangiopathy, has been described in patients with longstanding diabetes mellitus and

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microvascular complications (28).

Thyroid Disease The liver is the major site of thyroid hormone metabolism. Up to 85% of extrathyroidal deiodination of thyroxine (T 4 ) to triiodothyronine (T 3 ) and reverse T 3 (rT 3 ) occurs in the liver. Moreover, plasma-binding proteins of thyroid hormone, including thyroxine-binding globulin, prealbumin, and albumin, are produced by the liver. In addition, the liver is involved in the conjugation, biliary excretion, and oxidative deamination of T 4 . Thyroid hormones are also important for normal hepatic function and bilirubin metabolism; for example, thyroid hormone appears to play an important role in regulating the activity of uridine 5′-diphosphate glucuronyltransferase, the hepatic enzyme that is primarily responsible for the conjugation of bilirubin before hepatic excretion (29,30). A summary of the features of thyroid-related liver disease is shown in Table 11.1.

Table 11.1. Hepatic Abnormalities Associated with Various Thyroid Diseases and Therapies

Methimazole and Thyrotoxicosis

Hypothyroidism

Propylthiouracil therapy

carbimazole therapy

Aminotransferase elevations

++

+

++

–

Alkaline phosphatase

++

+

–

+

+

+

–

+

Liver biopsy

Lobular

Centrilobular

Nonspecific

Intrahepatic

findings

inflammation, hepatocyte

fibrosis in patients with

hepatocellular injury

cholestasis

nuclear changes, Kupffer cell

ascites

Hepatocellular necrosis in 12 min

Riley (114)

Intraperitoneal bleeding

PC + plug

1/20 (5%)

NR

Tobin (115)

Decrease in hematocrit

PC + plug

1/100 (1%)

NR

McVay (116)

Hemoglobin decrease by 2 g/dL

PC

4/65 mild coagulopathy; 0/11 moderate (5.3% total)

4/100 (4%)

Papatheodoridis (117)

Requiring transfusion

TJ

0/112

0/45

Bruzzi (118)

Undefined

TJ

0/31

0/19

Smith (119)

Intraperitoneal hemorrhage detected clinically and by computed tomography

TJ

3/203 (1.5%)

0/168

PT, prothrombin time; Lap, laparoscopic biopsy; PC, percutaneous; NR, not recorded; TJ, transjugular. Table adapted from Segal JB, Dzik WH. Paucity of studies to support that abnormal coagulation test results predict bleeding in the setting of invasive procedures: an evidence-based review. Transfusion 2005;45(9):1413–1425 (120).

Orthotopic liver transplantation Bleeding complications are frequent in liver transplantation and directly correlate with the morbidity and mortality of the procedure (121). The mechanisms underlying coagulopathy of liver transplantation can be divided into three surgical stages:

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Preanhepatic, anhepatic, and postanhepatic stages. In the preanhepatic stage of transplantation, the liver is surgically isolated. Bleeding during this stage may correlate with underlying coagulopathy, portal hypertension, and complexity of surgical intervention (122,123), although other analyses have failed to even P.359 identify coagulopathy as a risk factor for intraoperative blood loss (124). Bleeding during anhepatic stage is characterized by oozing in the previously dry surgical bed. Laboratory findings suggestive of DIC have been demonstrated in earlier series but later studies have not confirmed significant changes in PTT or PT before reperfusion of the donor graft, which may be due to improved surgical techniques (125,126,127,128). Hyperfibrinolysis during the anhepatic stage is well documented and appears to correlate with an increase in circulating tissue-type plasminogen activator (t-PA) levels in the absence of hepatic clearance (129). Accelerated fibrinolysis also frequently complicates the postanhepatic stage, which has led to the evaluation of antifibrinolytic agents in liver transplantation.

Table 12.3. British Society of Gastroenterology Guidelines on the Management of Patients with Coagulopathy Requiring Percutaneous Liver Biopsy

British Society of Gastroenterology guidelines for percutaneous liver biopsy

z

z

z

z

Platelet count and prothrombin time should be checked in the week prior, provided that the patient's liver disease is stable. If platelet count is >60,000/mm 3 then the biopsy can be safely performed. If the platelet count is 40,000–60,000/mm 3 then platelet transfusion may increase the count enough for the biopsy to be performed safely by the percutaneous route. If, however, platelet transfusion does not increase or the platelet count is Tab le o f Co nte nts > Volume I > Section II - Ge neral Conside rations > Ch ap te r 13 - Nutrition and the Liver

Chapter 13 Nutrition and the Liver Alan L. Buchman Kevin Korenblatt Samuel Klein

Key Concepts z

Energy expenditure is close to that predicted in patients with acute hepatitis and stable cirrhosis but is increased with respect to lean body mass. Energy expenditure is also increased in patients with hepatocellular carcinoma and in those with ascites.

z

Both protein synthesis and metabolism are impaired in patients with hepatic dysfunction. Specifically, visceral protein synthesis is decreased, and therefore, serum albumin and prealbumin are not useful in the assessment of nutritional status.

z

Patients with cirrhosis exhibit peripheral insulin resistance and hyperglycemia, and even overt diabetes may develop.

z

Protein-energy malnutrition (PEM) is common in patients with chronic liver disease and is often related to the severity of the underlying liver disease. Malnutrition is associated with increased infection risk, multiple organ complications, esophageal variceal hemorrhage, and increased post-transplantation morbidity and mortality.

z

Vitamin A, D, and E deficiency may develop in patients with chronic cholestatic disease such as primary biliary cirrhosis.

z

Many patients with metabolic syndrome also develop nonalcoholic steatohepatitis (NASH).

z

Hepatic dysfunction associated with the use of parenteral nutrition may more likely be the result of malabsorption rather than direct toxicity from the parenteral nutrient solution. Choline deficiency has been invoked as a primary cause for the hepatic steatosis that develops, and experimental data suggests a second hit, such as that from endotoxin, may be necessary for the development of more progressive liver disease.

z

Some patients with alcoholic hepatitis, as well as those with cirrhosis, may have improved morbidity and survival with the institution of either enteral or parenteral nutritional support.

z

Protein restriction should not be considered routine in patients with cirrhosis because most patients will tolerate an increased amount of standard dietary protein without development of or worsening of encephalopathy. Portosystemic encephalopathy should be aggressively treated using standard therapy before instituting dietary protein restriction. Select patients with hepatic encephalopathy may benefit from use of high branched-chain/low aromatic amino acid formulas.

z

Because of ineffective gluconeogenesis, a continuous glucose or dextrose supply should be provided to the patient with hepatic failure awaiting liver transplantation. Post-transplantation indications for nutritional support are similar to other nontransplantation postoperative indications.

P.366 The liver serves many critical metabolic and nutritional functions. It is the major site for (i) the synthesis of key plasma proteins, such as albumin and coagulation factors; (ii) urea synthesis needed for normal nitrogen and ammonia metabolism; (iii) glucose production to maintain glucose homeostasis and prevent hypoglycemia; (iv) lipoprotein production and export of water-insoluble triglycerides from the liver as water-soluble very low density lipoprotein (VLDL)–triglyceride particles into the bloodstream; (v) ketone body production, which provides fuel for the brain during energy or carbohydrate restriction; (vi) catabolism of metabolic regulatory hormones, such as insulin; and (vii) production of inflammatory markers, such as C-reactive protein. These diverse metabolic functions require a considerable amount of energy. Although the liver represents only approximately 2% of body weight, it accounts for approximately 20% of the body's resting energy requirements. Serious liver disease not only impairs hepatic function but also has considerable extrahepatic metabolic effects on glucose (insulin resistance and impaired glucose tolerance), lipid (increased lipolytic rates), and protein (decreased protein synthesis and increased amino acid oxidation rates) metabolism (1). Therefore, liver function, nutrition, and metabolism are integrally related, and abnormalities in one have adverse effects on the other.

Metabolic and Nutritional Principles Energy Intake and Absorption The average person ingests approximately 50 million calories, composed of approximately 2,000 kg of protein, 8,000 kg of carbohydrates, and 2,500 kg of fat, during his/her lifetime. Therefore, the balance between energy intake and energy expenditure is carefully regulated to permit normal growth during childhood and pregnancy and prevent large changes in body composition during adulthood. Food intake is controlled by a complex interaction of peripheral and central systems that determines the size, content, and frequency of feedings (2). These regulatory mechanisms must integrate daily short-term bursts of energy intake (meals and snacks) with long-term energy requirements and body composition. The regulation of energy intake is further complicated by the influence of external environmental cues, which can override endogenous regulatory signals and cause under- or overconsumption of energy. Patients with cirrhosis often experience alterations in nutrient intake, which can lead to weight loss. Several mechanisms contribute to decreased food intake, including decreased sensation to salty, bitter, sweet, and sour tastes; dysgeusia due to vitamin A or zinc deficiency (3,4); early satiety associated with ascites; medication-induced anorexia or nausea; and psychological or neurologic impairment that alter eating behavior (5). Alcohol intake can account for more than 50% of daily energy intake in some patients with alcoholic liver disease. Excessive alcohol is metabolized in part by the microsomal ethanol oxidizing system, which generates a wasteful energy cycle by producing heat without energy production (6). Malabsorption can also contribute to weight loss in patients with liver disease, even when appetite is unchanged. Chronic cholestasis and decreased bile acid secretion reduces the formation of mixed micelles, which impairs fat (7,8) and fat-soluble vitamin absorption (9). Malabsorption can also be caused by lactulose therapy, which can exacerbate steatorrhea (8), and by small bowel bacterial overgrowth (10,11,12,13), which occurs because of impaired small bowel motility (14,15,16,17) and prolonged intestinal transit (11,18,19). Some patients with alcoholic liver disease have serious malabsorption because of pancreatic insufficiency or direct alcohol-induced injury of the small intestine.

Energy Metabolism Energy is constantly required for normal organ function, metabolism, heat production, and muscular work. Resting energy expenditure (REE) is the amount of energy consumed during postabsorptive resting conditions and represents approximately 70% of total daily energy expenditure (TDEE). The thermic effect of feeding is the amount of energy expended during consumption and processing of ingested food and represents approximately 10% of TDEE. The energy expenditure of physical activity depends on the intensity and duration of daily activities but normally represents approximately 20% of TDEE. An assessment of energy requirements is necessary to make appropriate decisions about dietary intake and nutritional therapy in patients with liver disease. The Harris-Benedict equation developed in 1919 (20) is P.367 still a useful tool for estimating REE in adult men and women: Men: REE = 66 + (13.7 × W) + (5 × H) - (6.8 × A) Women: REE = 665 + (9.6 × W) + (1.8 × H) - (4.7 × A)

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where W, weight in kg; H, height in cm; A, age in years. The Harris-Benedict equation generates estimates of REE that are usually within 10% to 15% of measured values for healthy subjects (21). However, the values are less reliable in obese (tends to overestimate REE) or very lean (tends to underestimate REE) patients. In addition, hypocaloric feeding decreases REE to values that are 15% to 20% below those expected for actual body size, whereas metabolic stress, such as inflammatory diseases or trauma, increase energy requirements. The effect of liver disease on energy requirements is confusing because of conflicting data from different studies. Patients with liver disease have been reported to have low, normal, and high resting metabolic rates (14,22,23,24). Part of the inconsistency across studies can be attributed to how the data are expressed and the clinical condition of the patient. For example, in patients with either acute hepatitis or stable cirrhosis, energy expenditure is normal when it is expressed with respect to body surface area but is increased when it is expressed with respect to lean body mass (15,25). Energy expenditure is also increased in patients who have hepatocellular carcinoma, in relation to tumor size (26,27). Patients with severe disease, such as those with acute hepatic failure, usually have a marked increase in energy expenditure (28,29). Energy expenditure is increased in patients with ascites and decreases after ascites is removed by paracentesis (30). Energy expenditure can be determined by indirect calorimetry, which measures whole body oxidation of fuels. This is usually performed by using a metabolic cart to assess oxygen consumption and carbon dioxide production and can be helpful in certain patients, such as those with increased energy requirements (e.g., closed head injury, burn, and trauma), decreased energy requirements (e.g., cachexia), difficulty weaning from mechanical ventilation, and fluid overload, making it difficult to determine dry weight. However, the values obtained by indirect calorimetry require an experienced operator and carefully calibrated equipment used under appropriate conditions to obtain reliable results. Indirect calorimetry can be used to estimate basal energy expenditure, derived from oxygen and carbon dioxide consumption using the Weir equation [basal energy expenditure (kcal/day) = (3.941 × VO 2 [L/day]) + (1.106 × VCO 2 [L/day])] (31). Because oxygen phosphorylation allows continuous adenosine triphosphate (ATP) synthesis at the respiratory chain level, a close relationship exists between energy metabolism and oxygen consumption. The rate of ATP utilization determines the overall rate of substrate oxidation, and therefore, oxygen consumption. Indirect calorimetry is performed over a 20- to 30-minute period while the patient is at rest, but not sleeping; extrapolation to daily energy expenditure is undertaken. Indirect calorimetry is portable and noninvasive, and may be performed on spontaneously breathing or mechanically ventilated (FIO 2 60%) patients (Figs. 13.1A and B). In patients with cirrhosis, the liver comprises 20% to 30% of the whole body energy expenditure. Hypo- or hypermetabolism occur when the estimated energy expenditure varies by more than 10% of that predicted on the basis of the Harris-Benedict equation (20). Data from studies that evaluated substrate oxidation by using indirect calorimetry suggests that cirrhosis shifts basal fuel use from carbohydrate to fat oxidation, presumably because of diminished hepatic glycogen stores and hepatic glucose production (15,16,25). In general, stable patients with liver disease or cirrhosis require approximately 30 kcal/kg per day.

Starvation During starvation, an integrated series of metabolic adaptations occur that require important metabolic alterations for survival, including hepatic glycogenolysis and gluconeogenesis to maintain plasma glucose concentrations, decreased urea production in the liver to conserve body nitrogen, increased lipolysis and fatty acid release into plasma to provide tissues with fuel, and conversion of fatty acids to ketone bodies in the liver to provide a source of fuel for the brain and spare oxidative glucose requirements. Patients with cirrhosis have accelerated metabolic response to short-term starvation, manifested by a greater decline in hepatic glucose production, presumably related to decreased hepatic glycogen, and increased lipolysis of adipose tissue triglycerides (32). Death from starvation is associated with a body weight loss of more than 35% of body weight, protein depletion of more than 30% of body protein, fat depletion of more than 70% of body fat stores, and body mass index (BMI) of 13 kg/m 2 or less for men and 11 kg/m 2 or less for women (33,34,35). Therefore, the duration of survival during starvation depends on the amount of available body fat and lean tissue mass and appropriate hepatic adaptations, which are compromised in patients with liver disease.

Protein Metabolism Proteins are composed of a combination of 20 different amino acids, which are considered to be essential because the body cannot synthesize the carbon skeletons. Other amino acids are nonessential because they can be made from endogenous compounds. In some disease states, P.368 nonessential amino acids may become “conditionally essential.” For example, cysteine is essential in patients with cirrhosis because the transsulfuration pathway, which provides a sulfur group from methionine to cysteine, is impaired (36). The defect in trans-sulfuration affects methionine metabolism, which can lead to hypermethioninemia (37,38,39,40,41,42).

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▪ Figure 13.1 A: Indirect calorimetry in a spontaneously breathing patient. B: Indirect calorimetry in a mechanically ventilated patient. (Reprinted with permission from Buchman AL. Practical nutritional support techniques, 2nd ed. Thorofare, NJ: Slack Inc., 2004.)

The liver is an important site for amino acid and ammonia metabolism. Transamination reactions are catalyzed by transaminases or aminotransferases (e.g., alanine transaminase [ALT] and aspartate transaminase [AST]), which interconvert a pair of amino acids with a pair of keto acids. An increase in serum transaminase concentration is a sign of liver injury and represents its P.369 leakage from injured hepatocytes into the bloodstream. Ammonia, which is toxic to the central nervous system, is formed by oxidative deamination of glutamate in the liver, amino acid deamination in the kidneys, and intestinal bacterial production, and is absorbed and delivered to the liver through the portal vein. The liver rapidly removes ammonia from the circulation by formation of glutamate, glutamine, and urea. However, these metabolic processes can be impaired in patients with cirrhosis, causing an increase in circulating ammonia, which may contribute to hepatic encephalopathy (43). A major function of the liver is to synthesize and secrete proteins that are necessary for normal metabolic function into the systemic circulation. Hepatic synthesis of albumin, which is necessary for maintaining normal intravascular oncotic pressure and transporting nutrients, and the synthesis of fibrinogen and clotting factors, needed for normal coagulation, are impaired in patients with advanced cirrhosis (44,45). In addition, steatohepatitis is associated with a lower rate of hepatic VLDL-apolipoprotein B production than in obese patients without steatohepatitis (46). Muscle wasting occurs frequently in patients with cirrhosis (47). Skeletal muscle protein breakdown is often accelerated and nonoxidative leucine disposal is decreased in patients with cirrhosis (48). These alterations in amino acid metabolism can contribute to muscle wasting by enhancing protein breakdown in conjunction with diminished availability of amino acids for muscle protein synthesis. Protein requirements are affected by the amount of nonprotein calories consumed, overall energy requirements, and protein quality. Inadequate amounts of any of the essential amino acids result in inefficient utilization. In general, approximately 15% to 20% of total protein requirements should be in the form of essential amino acids in healthy adults. The metabolic stress of illness often increases protein requirements by increasing protein catabolism and metabolic rate. Therefore, daily protein requirements in patients with serious liver disease who do not have encephalopathy (approximately 1.0 to 1.2 g/kg) may be greater than the protein requirements in the healthy adult population (approximately 0.8 g/kg) (Table 13.1) (49). Nitrogen balance is calculated as the difference between nitrogen intake, in the form of amino acids or protein, and nitrogen losses in urine, stool, skin, body fluids, and nonprotein nitrogen. Nitrogen balance can be used to estimate protein balance because approximately 16% of proteins consists of nitrogen, and it is assumed that all the body nitrogen is incorporated into proteins. A positive balance (intake greater than losses) represents anabolic conditions and a net increase in total body protein content, whereas a negative balance demonstrates net protein catabolism. For example, a negative nitrogen balance of 1 g/day represents a 6.25-g/day (16% of 6.25 g protein = 1 g nitrogen) loss of body protein, which is equivalent to a 30-g/day loss of hydrated lean tissue. Total dietary nitrogen intake (grams) can be calculated by dividing the total protein intake (grams) over a 24-hour period by 6.25. Total urinary nitrogen (TUN), or urine urea nitrogen (UUN) + 4 to account for nonurea nitrogen losses (collected over the same 24-hour period as dietary intake), is then subtracted from the total nitrogen intake to arrive at the nitrogen balance. In practice, nitrogen balance studies tend to be artificially positive because of overestimation of dietary nitrogen intake and underestimation of losses caused by incomplete urine collections and unmeasured outputs.

Table 13.1. Recommended Daily Protein Intake

Clinical condition

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Protein requirements (g/kg ideal body weight/d)

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Normal

0.75

Metabolic “stress” a

1.0–1.5

Hemodialysis

1.2–1.4

Peritoneal dialysis

1.3–1.5

Continuous dialysis

1.7–2.0

a

Including patients with liver disease who have encephalopathy.

Additional protein requirements are needed to compensate for excess protein loss in patients with burn injuries, open wounds, and proteinlosing enteropathy or nephropathy. Lower protein intake may be necessary in patients with chronic renal insufficiency not treated by dialysis and in patients with liver disease and hepatic encephalopathy.

It is important to consider the patient's nutritional status when interpreting nitrogen balance data. When a person ingesting a low-protein diet is refed protein, nitrogen excretion does not rise proportionately to intake and there is retention of administered nitrogen. This gain during early refeeding is caused by a rapid accumulation of nitrogen in the liver and to a lesser extent in kidneys and muscle. However, the early retention of nitrogen is not sustained and nitrogen content decreases markedly within 4 to 7 days. In contrast, when a person ingesting a high-protein diet decreases his or her protein intake, the previously high urinary nitrogen loss continues for a few days despite the reduced intake, resulting in a negative nitrogen balance. Similarly, initial nitrogen loss after injury is greater in well-nourished than in malnourished patients. Therefore, a “labile” nitrogen pool of approximately 60 g contributes to short-term alterations in nitrogen balance. It must also be understood that a positive nitrogen balance requires a positive energy balance to avoid catabolism of skeletal muscle protein (50), although a positive nitrogen balance does not necessarily indicate adequate nitrogen utilization because protein metabolism is impaired in cirrhosis and end-stage liver disease. P.370

Glucose Metabolism After a person fasts overnight (12 hours), the liver produces approximately 2 mg of glucose/kg body weight (51). Adequate hepatic glucose production is critical because certain tissues, such as bone marrow, erythrocytes, leukocytes, renal medulla, eye tissues, and peripheral nerves, cannot metabolize fatty acids and require glucose (approximately 40 g/day) as a fuel, whereas other tissues, such as the brain, prefer glucose (approximately 120 g/day) as a fuel. Severe liver disease and cirrhosis can compromise the liver's capacity for glucose production (52). Hepatic glucose production is an important determinant of basal plasma glucose concentrations. Therefore, impaired insulin-mediated suppression of endogenous hepatic glucose output can cause basal hyperglycemia and contribute to the development of diabetes. Excess fat in the liver (nonalcoholic fatty liver disease [NAFLD]) is associated with insulin resistance and features of the metabolic syndrome, including abdominal fat accumulation, diabetes, hypertriglyceridemia, low serum high-density lipoprotein (HDL) concentrations, and hypertension (53,54,55,56,57). Data from one study found that lean men with excessive intrahepatic fat content (approximately 11% of liver volume) had impaired insulin-mediated suppression of endogenous glucose production compared with lean men who had low liver fat content (approximately 2% of liver volume) (58). Moreover, moderate weight loss decreases intrahepatic fat content and normalizes hepatic insulin sensitivity (59). The mechanisms underlying the relationships among hepatic fat, insulin resistance, and dyslipidemia are not known. It is possible that increased release of fatty acids from adipose tissue in obese persons simultaneously causes insulin resistance, dyslipidemia, and increased hepatic fat content. Excessive release of free fatty acids (FFAs) into plasma can impair the ability of insulin to stimulate muscle glucose uptake (60) and suppress hepatic glucose production (61,62) and can increase hepatic VLDL-triglyceride production and plasma triglyceride concentration (63). Therefore, increased hepatic fat content, insulin resistance, and dyslipidemia may be a sequelae of excessive fatty acid availability that can track together. However, it is also possible that increased hepatic fat itself has independent pathophysiologic effects by increasing intrahepatic fatty acids, which stimulate glucose production (61); fat metabolites, such as diacylglycerol and fatty acyl CoA; and ceramides, which impair insulin signaling in skeletal muscle (64). Patients with cirrhosis exhibit resistance to insulin-mediated glucose metabolism in skeletal muscle. Despite normal endogenous hepatic glucose production (65,66,67), hyperglycemia or overt diabetes has been reported in 15% to 30% of patients with cirrhosis (68). Pancreatic β-cells are unable to secrete sufficient insulin to overcome peripheral insulin resistance (69), although prolonged hyperinsulinemia related to decreased insulin metabolism may actually account for the insulin resistance (70). Insulin resistance resolves after liver transplantation (71).

Lipid Metabolism Lipids serve as a source of energy; structural components of cell membranes; precursors for steroid hormones, prostaglandins, thromboxane, and leukotriene synthesis; and carriers of essential nutrients. Plasma lipoproteins are molecular complexes of lipids and apolipoproteins that permit the transport of water-insoluble lipid species in the bloodstream. These complexes consist of a hydrophobic lipid core containing triglycerides and cholesterol esters with an outer surface of more hydrophilic phospholipids, free cholesterol, and apolipoproteins. One or more apolipoproteins are associated with each particle. Lipoproteins comprise a spectrum of particles of differing lipid content, apolipoproteins, and sizes and are commonly classified as chylomicrons, VLDL, low -density lipoprotein (LDL), and HDL on the basis of their floatation in an ultracentrifuge. VLDLs, produced by the liver, are the major endogenous triglyceride-rich lipoproteins. Obesity and NAFLD are associated with increased rates of hepatic VLDLtriglyceride production, which decrease with moderate weight loss (72). Dietary lipids are composed mainly of triglycerides: Long-chain triglycerides (LCTs), which contain fatty acids that are more than 12 carbons in length, or medium-chain triglycerides (MCTs), which are 6 to 12 carbons in length. MCTs do not require bile acids for absorption and are released directly into the portal vein after intestinal absorption. The use of MCTs can be beneficial in patients who have disorders of fat digestion (e.g., pancreatic insufficiency, biliary obstruction), fat absorption (e.g., celiac sprue, short bowel syndrome), or lipid transport (e.g., intestinal lymphangiectasia, abetalipoproteinemia), or in those who require a reduction in lymphatic flow (e.g., chylous ascites, thoracic duct fistula) (73). However, MCTs are more ketogenic than LCTs and should not be given to patients with cirrhosis, particularly those with portal–systemic shunts.

Major and Trace Minerals Major minerals are inorganic nutrients that are required in large (>100 mg/day) quantities and are important for maintaining ionic equilibrium, water balance, and normal cell function. In patients with cirrhosis, excess whole body sodium exacerbates edema and ascites (74), and hypokalemia can precipitate encephalopathy (75). P.371

Micronutrients Micronutrients consist of trace elements and vitamins, which are constituents of enzyme complexes that regulate metabolic processes. Trace minerals are inorganic nutrients that are required in small ( Table of Contents > Volume I > Section III - Consequences of Liver Disease > Chapter 16 - Surgical Management of Portal Hypertension

Chapter 16 Surgical Management of Portal Hypertension J. Michael Henderson

Key Concepts z

Liver transplantation has significantly improved outcome among Child-Pugh class C patients with variceal bleeding.

z

Evaluation of patients with portal hypertension being considered for surgery requires endoscopy, vascular imaging, and assessment of the liver disease.

z

Primary therapy for variceal bleeding is with endoscopic and pharmacologic modalities.

z

Variceal decompression is indicated for patients who fail primary therapy or who cannot undergo primary therapy. Decompression is performed with a transjugular intrahepatic portosystemic or surgical shunt.

z

All surgical shunts—total, partial, or selective—control variceal bleeding in more than 90% of patients.

z

The occurrence of encephalopathy and liver failure after insertion of a shunt depends on the extent of liver disease and loss of portal perfusion.

z

Devascularization procedures are a surgical alternative in the management of variceal bleeding in patients who cannot undergo shunting.

History Surgical management of portal hypertension was initiated in the late 19th century when Nicolai Eck first performed end-to-side portacaval shunts in dogs (the Eck fistula). Pavlov, more famous for his studies in gastric physiology, used this animal model of shunting all portal flow

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away from the liver to describe the portaprival syndrome characterized by meat intoxication (encephalopathy), progressive muscle wasting, and inanition. In the early 1900s, Vidal performed the first portacaval shunt in humans, and Drummond, Morrison, and Talma developed surgeries for portal hypertension in attempts to control variceal bleeding or manage ascites. Banti popularized splenectomy on the basis of his belief that splenomegaly was etiologic in portal hypertension. None had long-term success, but their ideas were the forerunners of much of what followed later (1). In the 1940s Whipple and the Columbia group reintroduced decompressive shunts for the management of variceal bleeding. His rationale was (i) the recognition that variceal bleeding was not controlled by splenectomy, (ii) that in patients with advanced cirrhosis the portal flow often reduced spontaneously, and (iii) that animal studies with dietary protein restriction had shown that encephalopathy could be controlled (2). Despite the fact that initial results were good, in large part because of the attention to detail and technical skill, longer follow-up showed that although bleeding could be controlled, shunting led to accelerated liver failure and encephalopathy. Randomized clinical studies ensued first with prophylactic shunts in patients with varices that had not bled and subsequently in patients after an initial variceal bleed. These trials in P.486 the 1960s and 1970s showed no significant advantage in patient survival of portosystemic shunts over nonsurgical therapy. The mode of death changed from bleeding to liver failure (3). In the 1970s and 1980s, surgeons remained active in the field of portal hypertension. Selective variceal decompression was introduced by Warren et al. (4) in the United States and Inokuchi (5) in Japan. They documented that varices could be selectively decompressed with good control of bleeding, maintenance of portal perfusion of the liver, and a lower rate of encephalopathy. Devascularization procedures became more extensive, largely popularized by Sugiura and Futagawa (6) in Japan and Hassab (7) in Egypt. The 1970s also saw the reintroduction of endoscopic sclerotherapy, initially by three surgeons, Johnston, Terblanche, and Paquet. Although initially performed with a rigid esophagoscope, sclerotherapy rapidly moved to flexible endoscopy and was performed by gastroenterologists. In the 1980s the success of sclerotherapy in treating acute bleeding and as first-line treatment to prevent rebleeding diminished the use of shunts (8). Endoscopic therapy evolved with banding replacing injection sclerotherapy in the 1990s (9). The late 1980s and 1990s saw two other major changes in the treatment of portal hypertension. Liver transplantation became widely used, with excellent outcomes for patients with end-stage liver disease

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(10). Second, transjugular intrahepatic portosystemic shunt (TIPS) was introduced in the 1990s (11) and has led to renewed interest in decompressive shunts in the care of patients with adequate liver function who bleed despite endoscopic and pharmacologic therapy but do not need liver transplantation.

▪ Figure 16.1 Portal venous anatomy. The portal vein is formed by the union of the superior mesenteric and splenic veins behind the neck of the pancreas. The main tributaries are the inferior mesenteric, left and right gastric, and gastroepiploic veins.

Anatomy Portal venous anatomy is remarkably consistent, considering the complexity of its embryologic development (Fig. 16.1). The portal vein is formed behind the neck of the pancreas by the confluence of the superior mesenteric and splenic veins. The portal vein is normally 10 to 12 mm in diameter but can enlarge up to 20 mm in portal hypertension. It follows a consistent course in the free edge of the gastrohepatic ligament to the porta hepatis, where it divides into right and left branches. The precise sites of entry of other feeding tributaries to this system, which are of clinical relevance in portal hypertension, are more variable. The inferior mesenteric vein enters the splenic vein in approximately two thirds of persons and the superior mesenteric vein in one third. It always serves as an outflow from the portal vein in portal hypertension. The left gastric or coronary vein enters the portal vein in approximately two thirds of persons and the splenic vein in the other one third. The left gastric vein varies considerably in size and may be the major feeding vein of

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gastroesophageal varices. P.487 The umbilical vein is constant in its communication with the left branch of the portal vein, and recanalization of this vessel in portal hypertension may open it to a significant size. An understanding of the pattern of tributaries to the portal vein is important to the surgeon both for liver transplantation and for shunts. The hepatic arterial blood supply is highly variable, and anomalies are of clinical significance to transplantation surgeons, particularly during donor hepatectomy. The normal arterial anatomy is a common hepatic artery arising from the celiac axis and giving rise to right and left hepatic arteries after the gastroduodenal artery leaves the common hepatic trunk. Approximately 20% of persons have an anomalous right accessory or replaced hepatic artery arising from the superior mesenteric artery. The incidence is similar for an accessory or replaced left hepatic artery, which arises from the left gastric artery. These two anomalies can coexist. The segmental anatomy of the liver subdivides eight segments according to their own major hepatic arterial and portal venous inflow and hepatic venous drainage. This subdivision of the liver is of particular importance in liver resection or for reduced-size liver transplantations. The physiologic functional unit of the liver is the liver lobule, and at this level the hepatic artery and portal venous blood mix, traverse the sinusoids, and drain through the central veins. The hepatic veins are consistent, with the right, middle, and left draining the segmental anatomy of the liver. The major pathologic changes of the portal venous anatomy in portal hypertension are at the gastroesophageal junction. Reevaluation with radiologic, ultrasound, and corrosion cast studies has shown that the submucosal and periesophageal veins communicate around the gastroesophageal junction through perforating vessels and align in a consistent pattern with the palisades that run in the submucosa in the distal 2 cm portion of the esophagus. This is the most common site of variceal bleeding.

Pathophysiology Normal portal venous pressure is 5 to 8 mm Hg, with a portal flow of 1 to 1.5 L/minute. The portal vein is a passive conduit that carries blood from the gastrointestinal tract to the liver. Total liver blood flow is regulated by intrinsic and extrinsic mechanisms, with alterations in portal flow causing a reciprocal increase or decrease in hepatic arterial flow. Portal hypertension is present when portal pressure exceeds 8 mm Hg, and the risk of variceal bleeding occurs at pressures greater than 12

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mm Hg. The pathophysiologic sequence of the events in portal hypertension has been defined in animal models (12). The initial resistance to portal venous flow is followed by the development of collateral vessels from the hypertensive bed to the systemic circulation. This is followed by increased plasma volume, development of a hyperdynamic systemic circulation, and marked splanchnic hyperemia, which contributes to the increased portal flow and pressure.

Evaluation When the surgeon is asked to evaluate a patient with portal hypertension, the focus is on issues pertinent to surgical intervention. A hepatologist has usually evaluated and managed the patient's liver disease and its complications already, and the current status should be defined. The main points of emphasis to the surgeon are the following: 1. Does the patient have decompensated cirrhosis? If this is the case, the only surgical option is liver transplantation. 2. Is the patient bleeding from varices? Have the varices reached a point where they cannot be adequately managed with first-line therapy? First-line management of variceal bleeding is endoscopic and pharmacologic therapy. However, 20% to 30% of patients have rebleeding and need additional therapy. Evaluation is accomplished with endoscopy and vascular imaging. Endoscopy may show varices that cannot be obliterated in the esophagus, gastric varices, or portal gastropathy as the site of bleeding. Doppler ultrasound should be used to show patency of and flow directions in the major veins, but if a decision is being made to perform decompression, angiography is usually needed to obtain details about the site of origin of collateral vessels. 3. Is the patient a suitable candidate for shunt surgery who is likely to survive the surgical procedure? This is primarily assessed by Child-Pugh classification (Table 16.1). Child-Pugh class A patients are surgical candidates. If the patients have no P.488 ascites or encephalopathy, their bilirubin level is less than 3 mg/dL, and the albumin level is greater than 3 g/dL, with an international normalized ratio less than 1.5, the surgeon can operate on them with the expectation of a reasonable outcome. Child-Pugh class B patients may be either class B improving toward class A or class B moving toward class C. In the care of Child-Pugh class C patients, the only realistic surgery is liver transplantation. The role of Model for End-Stage Liver Disease (MELD) scoring (Table 16.2) in assessing patients for shunt surgery has not been fully defined to the same extent as that

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used for transplantation.

Table 16.1. Child-Pugh Grading of Severity of Liver Disease

Patient score for increasing abnormality Clinical and laboratory measurement Encephalopathy

1

2

3

None

1 or 2

3 or 4

None

Mild

Moderate

1–2

2.1–3

≥3.1

≥3.5

2.8–

≤2.7

(grade)

Ascites

Bilirubin (mg/dL)

Albumin (g/dL)

3.5

Prothrombin time

1–4

4.1–6

≥6.1

(increase, s)

Child-Pugh grade is A when total score is 5–6, B when total score is 7–9, and C when total score is 10–15.

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Table 16.2. Model for End-Stage Liver Disease (Meld) Score

Score = 0.957 log e creatinine (mg/dL) + 0.378 log e bilirubin (mg/dL) + 1.120 log e INR

INR, international normalized ratio.

Portal Decompression Transjugular Intrahepatic Portosystemic Shunt TIPS emerged in the 1990s as an alternative to surgical decompression (Fig. 16.2) and is currently the most widely used shunt. This shunt, which is addressed in Chapter 15, must, however, also be considered when discussing the site for surgical decompression. Although a TIPS is placed more easily than a surgical shunt, it currently has the disadvantage of high rates of stenosis and thrombosis, leading to rebleeding within 2 years in approximately 20% of patients (13,14). The introduction of polytetrafluoroethylene covered stents has lowered the dysfunction rates, and in a European multicenter trial it reduced rebleeding to 13% at 2 years (15). However, the inability to identify “dysfunction” reliably without repeat shunt catheterization and pressure measurement adds to the complexity of follow-up and cost of TIPS. All patients need an intensive follow-up protocol after TIPS placement. The encephalopathy rate after TIPS appears to be similar to that after total shunt placement (13,16). TIPS is a good treatment for patients with portal hypertension, variceal bleeding, and ascites who are awaiting liver transplantation when bleeding is not controlled with endoscopic therapy (13). The role of TIPS in the care of lower-risk patients who may either have a longer bridge to transplantation or not need transplantation is addressed in subsequent text.

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▪ Figure 16.2 Transjugular intrahepatic portosystemic shunt. A track developed between a major hepatic vein and the portal vein is dilated and stented. This is a side-to-side portal systemic shunt, either total or partial.

Surgical Methods Three surgical methods are used in the management of portal hypertension: P.489 1. Decompressive shunts 2. Devascularization procedures 3. Liver transplantation There is a role for each of these operative procedures, and this section discusses the goals and outcome of these procedures.

Decompressive Surgical Shunts Decompressive surgical shunts fall into three groups: 1. Total portosystemic shunts that decompress all portal hypertension

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2. Partial portosystemic shunts that reduce portal hypertension to approximately 12 mm Hg 3. Selective shunts that decompress gastroesophageal varices but maintain portal hypertension

Total portosystemic shunts In the end-to-side portacaval shunt (Eck fistula) procedure, the liver end of the portal vein is ligated and the splanchnic end is anastomosed to the vena cava. With this shunt, the hepatic sinusoids maintain their hypertension; therefore, this surgery does not relieve ascites. Hence, there are currently almost no indications for this surgery at present. By contrast, the second group of total shunts are side-to-side shunts, all of which decompress the portal hypertension both in the splanchnic bed and in the liver (Fig. 16.3). These procedures still have some proponents. The common factor to these shunts is that they are 10 mm or more in diameter and include side-to-side portacaval, mesocaval, and central splenorenal shunts. They may either be direct vein-to-vein anastomoses or incorporate prosthetic material. The pathophysiology of these shunts is associated with the portal vein acting as an outflow tract from the obstructed sinusoids, with reversal of blood flow in the portal vein to the low-pressure shunt. Side-to-side shunts are excellent for controlling variceal bleeding and ascites but deprive the liver of prograde portal flow and increase the risks of progressive liver failure and encephalopathy (17,18,19). The other major disadvantage of these shunts is that when prosthetic material is used as an interposition graft, there is increased risk of thrombosis (20). The indications for side-to-side shunts are at present relatively limited. A patient with massive continued bleeding who also has ascites can be treated with a side-to-side shunt, although TIPS achieves the same goal without surgery. The strongest advocates of emergency side-toside portacaval shunts are Orloff et al. who in 1995 reported an extensive series with excellent outcome in a largely alcoholic group of patients (17). The other indication for this type of side-to-side shunt is acute Budd-Chiari syndrome because it allows decompression of the obstructed sinusoids and halts ongoing hepatocellular necrosis (21).

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▪ Figure 16.3 Side-to-side portacaval shunt. The portal vein and inferior vena cava must be mobilized sufficiently to allow them to be opposed for anastomosis. If the distance between the veins is too great, graft interposition may be needed.

Partial portosystemic shunts Partial portosystemic shunts can be achieved by reducing side-to-side portosystemic shunt diameter to 8 mm. Data show that at this size portal flow is maintained in 80% of patients, and portal hypertension is reduced to 12 mm Hg (22). This interposition portacaval shunt is illustrated in Figure 16.4. Attention to detail in the execution of this graft is critical to minimize the risk of thrombosis. Outcomes with partial shunts documented from two prospective, randomized controlled trials indicate control of bleeding in 90% of patients (23,24). The maintenance of some portal flow has been associated with a lower incidence of encephalopathy and liver failure than that with total portosystemic shunting. Other groups have

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advocated the use of a limited-size mesocaval shunt in a similar way and have presented data in support of this concept, although not from randomized, controlled studies (25,26). One randomized trial has compared the 8-mm portacaval surgical shunt to TIPS. In this “all-comers” study, 50% of patients had Child-Pugh C cirrhosis and 63% of the patients had alcoholic liver disease. There was P.490 significantly better control of bleeding and lower need for transplantation in the surgical shunt group compared to the TIPS group—survival was not significantly different (24).

▪ Figure 16.4 Partial portosystemic shunt. Interposition of an 8mm expanded polytetrafluoroethylene (Gore-Tex) graft between the portal vein and inferior vena cava reduces portal hypertension to 12 mm Hg and allows continued portal perfusion in 80% of patients.

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Selective shunts In selective variceal decompression, a different pathophysiologic concept is applied for the control of variceal bleeding. Varices are selectively decompressed, usually by a distal splenorenal shunt (DSRS) through the short gastric veins, spleen, and splenic vein to the left renal vein (4). Portal hypertension is maintained in the splanchnic and portal venous system to maintain prograde portal flow to the cirrhotic liver. This surgery is illustrated in Figure 16.5 and has been the most widely used surgical shunt worldwide over the last 20 years. This surgery should be part of the repertoire of liver transplantation surgeons for patients who have refractory bleeding but still have good liver function. Long-term patency of DSRS is excellent with the vein-to-vein anastomosis, and bleeding is controlled in more than 90% of patients (19,27,28,29,30,31,32,33). The highest risk time for rebleeding is in the first 4 to 6 weeks while the short gastric and renal veins accommodate the increased flow from the enlarged spleen and varices (34). Maintenance of portal perfusion is achieved in 90% of patients in the short term. Long-term maintenance of portal perfusion has proved excellent in nonalcoholic patients, but 50% of alcoholic patients lose portal perfusion unless splenopancreatic disconnection is performed. This has resulted in maintenance of portal flow in 84% of patients with alcoholic cirrhosis (35). Randomized controlled trials in which DSRS was compared with total shunts have shown equivalent control of bleeding (36). Although three of these six studies have shown lower incidence of encephalopathy after insertion of a DSRS, the others have not. These other studies were conducted with a predominantly alcoholic (83%) population, which may be a factor in the failure to show significant advantage for DSRS. Four randomized trials have been conducted in which DSRS was compared with endoscopic sclerotherapy (37). In these studies, use of a DSRS resulted in significantly better control of variceal bleeding. The rate of encephalopathy was not significantly different between sclerotherapy and shunt groups. This was the strongest evidence that DSRS does not accelerate the rate of encephalopathy in patients with cirrhosis. One study showed significantly improved outcome among patients initially randomized to sclerotherapy, one third of whom needed subsequent surgical salvage because of recurrent variceal bleeding (38). Another trial showed a significantly better outcome in patients initially randomized to DSRS (39). This difference was predominantly due to the failure to surgically rescue patients in the sclerotherapy group who have rebleeding because they were often geographically remote from the primary managing center. The other

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two trials showed no significant difference in survival. There is much interest in the comparative role of DSRS and TIPS. Several studies have looked at this (a) in a nonrandomized manner (40), in which the superiority of DSRS was demonstrated; (b) in relation to subsequent likely liver transplantation (41); and (c) in a decision analysis evaluation (42), which favored DSRS over TIPS in a cost analysis. A multicenter randomized trial has compared DSRS to TIPS in Child-Pugh class A and B patients who rebled through pharmacologic and endoscopic therapy (43). Sixty percent of the patients entered had alcoholic liver disease. At a median follow-up of 42 months, there was no significant difference in control of bleeding (DSRS 94%, TIPS 89%), time to first encephalopathy event (DSRS, 1 year 20%, 5 years 50%; TIPS, 1 year 22%, 5 years 50%), or survival (DSRS 1 year 85%, 5 years 62%: TIPS 1 year 90%, 5 years 61%). However, the TIPS patients required significantly (P < 0.001) more reinterventions (83%) compared to DSRS patients (11%). This emphasizes the need for careful protocol follow-up for TIPS patients— including shunt catheterization and pressure measurements—to achieve these results.

▪ Figure 16.5 Distal splenorenal shunt. Varices are selectively decompressed through the short gastric veins, spleen, and splenic vein to the left renal vein. Portal hypertension is maintained in the superior mesenteric and portal veins to keep portal flow to the

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liver.

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Devascularization Procedures Devascularization procedures have the components of splenectomy, gastric and esophageal devascularization, and in some situations, esophageal transection (Fig. 16.6). The advantage of these procedures is that they maintain portal hypertension and portal flow to the cirrhotic liver and do not accelerate liver failure or encephalopathy. The disadvantage is that they have a higher rate of rebleeding, which probably depends on the extent of the surgical procedure. Sugiura et al. devascularized from the pylorus to the inferior pulmonary veins using both thoracotomy and laparotomy to achieve an extensive procedure with a low rate of rebleeding (6,44). Lesser procedures using only a transabdominal approach, as performed in Europe and the United States, have rebleeding rates in the range of 20% to 40% (45). In patients who have extensive portal venous thrombosis and in whom no vessels can be shunted, devascularization procedures are the only surgical option. When these patients do not have bleeding controlled by pharmacologic and endoscopic therapy, extensive devascularization may significantly reduce the risk of rebleeding. This is the major indication for devascularization procedures.

Liver Transplantation Liver transplantation has dramatically altered the outcome for patients with advanced liver disease, portal hypertension, and variceal bleeding. It is the one therapy that has significantly improved survival of patients with bleeding varices and Child-Pugh class C cirrhosis. The indication for liver transplantation, however, is end-stage liver disease rather than variceal bleeding. Liver transplantation both restores hepatic function and relieves portal hypertension, making it the most effective shunt in the management of variceal bleeding. However, supply and demand dictate that transplantation cannot be the therapy for all patients with cirrhosis who have variceal bleeding. The evolution of national organ allocation standards for livers has had an impact on who receives the transplant. The sickest patients from the perspective of the severity of liver disease receive priority, and variceal bleeding per se does not increase priority. This appropriately drives the need P.492 to use the other modalities discussed in this chapter to treat variceal bleeding in patients who still have adequate liver function.

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▪ Figure 16.6 Devascularization procedures have the components of splenectomy and devascularization of the greater and lesser curves of the stomach, as well as the distal 7 cm of the esophagus.

The outcome of liver transplantation has dramatically improved in the last decade. Currently, patients can anticipate an initial 6-month mortality of approximately 10%, with continuing long-term risk of 2% to 5% per year for death or major morbidity. The major risk factors facing transplantation patients are recurrent disease, especially hepatitis, chronic rejection, and immunosuppression-related infection. In the context of this chapter, for the management of variceal bleeding, liver transplantation is the most viable long-term treatment option for patients with variceal bleeding and end-stage disease. Timing is always a major issue, and with the increasing lengthening of waiting lists it becomes more problematic. Determining the correct “bridge” to transplantation is key, and the least therapy that can be used as a bridge, the better it is for the patient. However, when patients have bleeding refractory to endoscopic therapy, it may be appropriate to decompress the portal hypertension with TIPS. Surgical decompression is also an appropriate bridge for a patient who has a

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disease that may not necessitate transplantation for 5 to 10 years.

Management Strategies for Variceal Bleeding Prophylaxis There is no indication for surgical intervention as prophylaxis before the first episode of variceal bleeding. Current data indicate that prophylaxis should be with pharmacologic therapy. In some patients at high risk with large varices, endoscopic therapy as prophylaxis against initial variceal bleeding may be indicated. The data on surgical prophylaxis are old, primarily being collected in the 1960s, but still lead to the recommendation of no surgical intervention before an initial episode of bleeding.

Acute Variceal Bleeding Primary therapy for acute variceal bleeding is endoscopic. Sclerotherapy or banding is done at the time of the initial diagnostic endoscopic procedure. This treatment may be combined with pharmacologic therapy to reduce the risk of early rebleeding. Surgical intervention is rarely indicated for acute variceal bleeding. P.493 More than 90% of patients can be treated with endoscopic therapy. In the small minority of cases in which this therapy fails, balloon tamponade with emergency decompression using TIPS in the next 24 hours is the best approach. The one exception to this view is that of Orloff et al. (17), who continue to advocate emergency portacaval shunting for acute variceal bleeding. The success of their approach is probably based on the patient population they treat and their commitment to early intervention and a program of long-term followup evaluation of these patients.

Prevention of Variceal Rebleeding Surgical intervention is part of an overall program for this group of patients but has been progressively replaced with new options. Initial first-line treatment is with pharmacologic and endoscopic therapies. Seventy percent of patients are successfully treated in this way. It is for the 30% of patients who have rebleeding through first-line treatment or in whom the varices are not obliterated that decompression should be considered. How should this decompression be achieved? A key decision at this point is whether the patient has end-stage liver disease or a disease that is rapidly approaching this stage. Patients who do have such disease should be fully evaluated for transplantation and moved in this direction. For patients who rebleed through first-line treatment and have adequate and stable liver function, the choice of surgical shunt or TIPS is based on availability,

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access to care, and commitment to follow-up. Both are equally efficacious in outcomes. Reaching decisions in patient care requires early and accurate evaluation. Once a patient's condition has been stabilized after acute variceal bleeding, the patient should undergo full evaluation as outlined earlier. Equally important for patients being treated with firstline therapy is to monitor whether the disease is stable and whether hepatocellular function is deteriorating or improving. Patient education is also key to the care of these patients over the long term so that they understand that there are other treatment options should firstline treatment fail.

New Trends as a Consequence of Improved Control of Variceal Bleeding The advances and improvements in the control of variceal bleeding in the last two decades have led to the increased recognition of other complications of cirrhosis, which were previously uncommon. Two that are clinically important, and should be considered in long-term management of these patients, are hepatocellular carcinoma (HCC) and the pulmonary complications of chronic liver disease. HCC is increasing in frequency for many reasons. Improved management of variceal bleeding, with overall improved survival of an “at-risk” population, is one contributing factor. Prospective evaluations of such patients by the Barcelona Group gave a 14% to 21% risk of HCC at 5 years, but their data do not indicate that shunts increase that risk (46). The pulmonary complications of cirrhosis are the hepatopulmonary syndromes (HPSs) and portopulmonary hypertension (PPH). HPS is seen in up to 15% of patients with cirrhosis (47), whereas PPH is less common. The role of portal–systemic shunting in the development of either of these has been widely debated. The pathophysiology of HPS is a nitric oxide–mediated pulmonary vasculature vasodilatation: How far this is triggered by mediators from the damaged liver or through portal systemic shunting is not fully defined (47). A larger multicenter review of both these complications in patients considered for transplantation did not implicate surgical or radiologic shunts as etiologies in the patients who were identified (48). The current data leaves open the question of the importance of shunting in these syndromes.

Annotated References Boyer TD, Haskal ZJ. The role of TIPS in the treatment of portal hypertension. Hepatology 2005;41:386–400. This paper summarizes the status of TIPS after its first decade of

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widespread use. Henderson JM, Nagle A, Curtas S, et al. Surgical shunts and TIPS for variceal decompression in the 1990′s. Surgery 2000;128:540– 547. This paper describes a series of surgical shunts inserted in the 1990s. The selection criteria and outcome for surgical shunts and TIPS in this decade are compared. Langer B, ed. Treatment of portal hypertension: world progress in surgery-state of the art. World J Surg 1994;18:169–258. A series of papers that gives a balanced worldwide perspective on the management of portal hypertension. Orloff MJ, Orloff MS, Orloff SL, et al. Three decades of experience with emergency portacaval shunt for acutely bleeding esophageal varices in 400 unselected patients with cirrhosis of the liver. J Am Coll Surg 1995;180:257–272. A surgeon's experience with emergency portacaval shunts. Evolution of the procedure and outcome over three decades are described. Rosemurgy AS, Serofini FM, Zweibal BR, et al. TIPS versus small diameter prosthetic H-graft portacaval shunt. J Gastrointest Surg 2000;4:589–597. This paper documents the superior outcome of this surgical shunt over TIPS in an “all-comers” population.

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2. Whipple AO. The problem of portal hypertension in relation to the hepatosplenopathies. Ann Surg 1945;122:449. P.494 3. Warren WD. Presidential address: controlled clinical research, opportunities and problems for the surgeon. Am J Surg 1974;127:3–8.

4. Warren WD, Zeppa R, Fomon JJ. Selective trans-splenic

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decompression of gastroesophageal varices by distal splenorenal shunt. Ann Surg 1967;166:437–455.

5. Inokuchi K. A selective portacaval shunt. Lancet 1968;2:51–52.

6. Sugiura M, Futagawa S. Esophageal transection with paraesophagogastric devascularizations (the Sugiura procedure) in the treatment of esophageal varices. World J Surg 1984;8:673– 679.

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9. Stegmann GV, Goff JS, Sunn JH, et al. Endoscopic variceal ligation: an alternative to sclerotherapy. Gastrointest Endosc 1989;35:431–434.

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12. Gupta TK, Chen L, Groszmann RJ. Pathophysiology of portal hypertension. Clin Liver Dis 1997;1:1–12.

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14. LaBerge JM, Somberg KA, Lake JR, et al. Two-year outcome following transjugular intrahepatic portosystemic shunt for variceal bleeding: results in 90 patients. Gastroenterology 1995;108:1143–

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15. Bureau C, Garcia-Pagan JC, Otal P, et al. Improved clinical outcome using polytetraflouroethylene-coated stents for TIPS: results of a randomized study. Gastroenterology 2004;126:469– 475.

16. Sanyal AJ, Freedman AM, Shiffman ML, et al. Portosystemic encephalopathy after transjugular intrahepatic portosystemic shunt: results of a prospective controlled study. Hepatology 1994;20:46–55.

17. Orloff MJ, Orloff MS, Orloff SL, et al. Three decades of experience with emergency portacaval shunt for acutely bleeding esophageal varices in 400 unselected patients with cirrhosis of the liver. J Am Coll Surg 1995;180:257–272.

18. Stipa S, Balducci G, Ziparo V, et al. Total shunting and elective management of variceal bleeding. World J Surg 1994;18:200–204.

19. Hermann RE, Henderson JM, Vogt DP, et al. Fifty years of surgery for portal hypertension at the Cleveland Clinic Foundation: lessons and prospects. Ann Surg 1995;221:459–466.

20. Smith RB, Warren WD, Salam AA, et al. Dacron interposition shunts for portal hypertension: an analysis of morbidity correlates. Ann Surg 1980;192:9–17.

21. Henderson JM, Warren WD, Millikan WJ Jr, et al. Surgical options, hematologic evaluation, and pathologic changes in BuddChiari syndrome. Am J Surg 1990;159:41–48.

22. Sarfeh IJ, Rypins EB, Mason GR. A systematic appraisal of portacaval H-graft diameters: clinical and hemodynamic perspectives. Ann Surg 1986;204:356–363.

23. Sarfeh IJ, Rypins EB. Partial versus total portacaval shunt in alcoholic cirrhosis: results of a prospective, randomized clinical trial. Ann Surg 1994;219:353–361.

24. Rosemurgy AS, Serofini FM, Zweibal BR, et al. TIPS versus

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small diameter prosthetic H-graft portacaval shunt: extended follow-up of an expanded randomized prospective trial. J Gastrointest Surg 2000;4:589–597.

25. Paquet KJ, Mercado MA, Gad HA. Surgical procedures for bleeding esophagogastric varices when sclerotherapy fails: a prospective study. Am J Surg 1990;160:43–47.

26. Mercado MA, Morales-Linares JC, Granados-Garcia J, et al. Distal splenorenal shunt versus 10-mm low-diameter mesocaval shunt for variceal hemorrhage. Am J Surg 1996;171:591–595.

27. Henderson JM, Gilmore GT, Hooks MA, et al. Selective shunt in the management of variceal bleeding in the era of liver transplantation. Ann Surg 1992;216:248–254.

28. Rikkers LF. Is the distal splenorenal shunt better? Hepatology 1988;8:1705–1707.

29. Orozco H, Mercado MA, Garcia JG, et al. Selective shunts for portal hypertension current role of a 21 year experience. Liver Transpl Surg 1997;3:475–480.

30. Rikkers LF, Jin G, Langnas AN, et al. Shunt surgery during the era of liver transplantation. Ann Surg 1997;226:51–57.

31. Henderson JM, Nagle A, Curtas S, et al. Surgical Shunts and TIPS for variceal decompression in the 1990's. Surgery 2000;128:540–547.

32. Knechtle SJ, D’Allessandro AM, Armbrust MJ, et al. Surgical portosystemic shunts for treatment of portal hypertensive bleeding: outcome and effect on liver function. Surgery 1999;126:708–711.

33. Jenkins RL, Gedaly R, Pomposelli JJ, et al. Distal splenorenal shunt: role, indications, and utility in the era of liver transplantation. Arch Surg 1999;134:416–420.

34. Richards WO, Pearson TC, Henderson JM, et al. Evaluation and treatment of early hemorrhage of the alimentary tract after

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selective shunt procedures. Surg Gynecol Obstet 1987;164:530– 536.

35. Henderson JM, Warren WD, Millikan WJ, et al. Distal splenorenal shunt with splenopancreatic disconnection: a 4-year assessment. Ann Surg 1989;210:332–339.

36. Henderson JM. Variceal bleeding: which shunt? Gastroenterology 1986;91:1021–1023.

37. Spina GP, Henderson JM, Rikkers LF, et al. Distal spleno-renal shunt versus endoscopic sclerotherapy in the prevention of variceal rebleeding: a meta-analysis of 4 randomized clinical trials. J Hepatol 1992;16:338–345.

38. Henderson JM, Kutner MH, Millikan WJ Jr, et al. Endoscopic variceal sclerosis compared with distal splenorenal shunt to prevent recurrent variceal bleeding in cirrhosis: a prospective, randomized trial. Ann Intern Med 1990;112:262–269.

39. Rikkers LF, Jin G, Burnett DA, et al. Shunt surgery versus endoscopic sclerotherapy for variceal hemorrhage: late results of a randomized trial. Am J Surg 1993;165:27–32.

40. Khaitiyor JS, Luthra SK, Prasod N, et al. Transjugular intrahepatic portosystemic shunt versus distal splenorenal shunt: a cooperative study. Hepatogastroenterology 2000;47:492–497.

41. Faust TW, Sorrell MF. Pre-liver transplant: TIPS versus distal splenorenal shunt. HPB Surg 1997;10:261–265.

42. Zacks SL, Sandler RS, Biddle AK, et al. Decision analysis of transjugular intrahepatic portosystemic shunt versus distal splenorenal shunt for portal hypertension. Hepatology 1999;29:1399–1405.

43. Henderson JM, Boyer TD, Kutner MH, et al. DSRS vs. TIPS for refractory variceal bleeding: a prospective randomized controlled trial [Abstract]. Hepatology 2004;40:725A.

44. Idezuki Y, Kokudo N, Sanjo K, et al. Sugiura procedure for

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management of variceal bleeding in Japan. World J Surg 1994;18:216–221. P.495 45. Dagenais M, Langer B, Taylor BR, et al. Experience with radical esophagogastric devascularization procedures (Sugiura) for variceal bleeding outside Japan. World J Surg 1994;18:222–228.

46. Elizalde JI, Castells A, Planas R, et al. Prevalence of hepatocellular carcinoma in cirrhotic patients with portosystemic shunt. Cohort analysis. Gastroenterol Hepatol 1996;19:189–193.

47. Fallon MB, Abrams GA. Hepatopulmonary syndrome. Curr Gastroenterol Rep 2000;2:40–45.

48. Krowka MJ, Mandell MS, Ramsay MA, et al. Hepatopulmonary syndrome and portopulmonary hypertension: a report. Liver Transpl 2004;10:174–182.

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Editors: Title:



Copyright ©2007 Lippincott Williams & Wilkins > Table of Contents > Volume I > Section III - Consequences of Liver Disease > Chapter 17 - Renal Complications and Hepatorenal Syndrome

Chapter 17 Renal Complications and Hepatorenal Syndrome Andrés Cárdenas Pere Ginès Juan Rodés

Key Concepts z

Renal impairment in most patients with cirrhosis is secondary to functional abnormalities that occur in response to a severe splanchnic arterial vasodilatation which triggers an intense homeostatic neurohumoral response causing sodium retention and solute-free water retention and, finally, severe renal vasoconstriction.

z

Sodium retention is the first and most common functional renal abnormality in patients with cirrhosis and plays a fundamental role in the formation of ascites and edema. The total amount of extracellular fluid accumulated as ascites or edema depends on the balance between sodium intake and excretion.

z

In the natural history of cirrhosis and ascites, in time, patients develop an impairment in the renal handling of solute-free water and retain water in excess of sodium. Those with a marked impairment in solute-free water excretion develop dilutional hyponatremia, a condition that carries a poor prognosis in patients with cirrhosis and ascites.

z

Treatment of spontaneous dilutional hyponatremia with V2 receptor antagonists in patients having cirrhosis and ascites seems to be a promising new therapy that enhances solute-free water excretion and raises serum sodium levels in this condition.

z

Hepatorenal syndrome (HRS) is the end of the spectrum of functional renal abnormalities caused by a severe vasoconstriction of the renal circulation. Patients with marked sodium and water retention are at high risk of developing HRS.

z

There are two types of HRS; type 1 is an acute and rapidly progressive form with a very poor prognosis and type 2 is a more stable form with a slightly better prognosis.

z

The short-term mortality rate in patients with HRS is very high. The type of HRS and the Model for End-stage Liver Disease (MELD) score are predictive factors of survival. Transplantation candidates should undergo transplantation with a high priority.

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HRS that develops in patients with cirrhosis after spontaneous bacterial

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peritonitis (SBP) or in the setting of acute alcoholic hepatitis can be prevented effectively. The administration of intravenous albumin together with antibiotic therapy in the former condition, and oral pentoxifylline in the latter prevent HRS. z

The treatment of HRS should be aimed at reversing the intense splanchnic arteriolar vasodilatation with splanchnic vasoconstrictors and plasma expansion as a bridge to liver transplantation. The use of transjugular intrahepatic portosystemic shunt also appears to be effective in select cases.

Table 17.1. Functional Renal Abnormalities in Cirrhosis

Abnormality

Clinical consequence

Sodium retention

Ascites and edema

Solute-free water retention

Spontaneous dilutional hyponatremia

Renal vasoconstriction

Hepatorenal syndrome

P.498 In the natural history of cirrhosis, a progressive derangement of renal function, which is functional in nature, leads to an inability to maintain the extracellular fluid volume within normal limits. This abnormal extracellular fluid volume regulation is due to alterations in the splanchnic and systemic arterial circulation that cause functional renal abnormalities, leading to sodium retention. The characteristic and predominant renal function abnormality in cirrhosis is sodium retention and its main clinical consequence is the recurrent accumulation of extracellular fluid as ascites and/or edema. Sodium retention, when severe, is often associated with an impaired ability to eliminate a regular water intake, which may lead to dilutional hyponatremia due to an unbalanced increase in total body water, relative to the total sodium content (i.e., water in excess of sodium). With disease progression a gradual vasoconstriction of the renal circulation usually develops because of circulating vasoconstrictors. This event causes renal hypoperfusion, reduction in glomerular filtration rate (GFR), and eventually renal failure or the so-called hepatorenal syndrome (HRS) (Table 17.1). All these abnormalities of renal function contribute significantly to the high morbidity and mortality, characteristic of cirrhosis. The mechanisms leading to renal dysfunction in cirrhosis are not completely understood and are still a matter of investigation. Extrarenal and intrarenal vasoactive factors, sodium and water retaining systems, abnormalities in systemic, cardiac and splanchnic hemodynamics, and the diseased liver causing severe portal hypertension and hepatic failure play an important role in the pathophysiology of HRS. This chapter describes the clinical characteristics,

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pathogenesis, and treatment of renal complications in patients with cirrhosis.

Clinical Features Sodium Retention and Ascites/Edema Sodium retention is the most common abnormality of renal function in patients with cirrhosis and ascites and plays a key role in the pathophysiology of ascites and edema formation (1,2,3). It is the first manifestation of renal impairment these patients develop (Fig. 17.1). The total amount of sodium retained by patients with cirrhosis and the subsequent gain of extracellular fluid is dependent on the balance between sodium intake and excretion. Patients accumulating ascites and edema invariably have a lower amount of sodium excreted in the urine than their dietary intake. However, if they decrease their sodium intake and use diuretics, sodium excretion increases and they lose extracellular fluid and ascites and/or edema decrease. Compensated patients with cirrhosis (no past history of ascites) usually do not retain sodium while consuming a normal diet, but may develop ascites and/or edema when sodium intake is increased (highsodium diet or administration of intravenous saline solutions) or when they are treated with drugs that increase sodium reabsorption, such as mineralocorticoids or nonsteroidal anti-inflammatory drugs (NSAIDS) (2,3,4,5). The intensity of sodium retention varies considerably from patient to patient. In baseline conditions (low-sodium diet and without diuretics) some patients have relatively high urinary sodium excretion, whereas in other patients, urinary sodium excretion is very low (Fig. 17.2) (6). The underlying mechanisms leading to this variability are not well understood; however, it seems that they could be related to the amount of circulating sodium-retaining systems (mainly aldosterone), increased sensitivity to these, or an increase in renal tubular sodium transporters regulated by aldosterone (2,7). Most patients who require hospitalization for the treatment of ascites have marked sodium retention with a very low baseline urinary sodium excretion (usually Table of Contents > Volume I > Section III - Consequences of Liver Disease > Chapter 19 - Ascites and Spontaneous Bacterial Peritonitis

Chapter 19 Ascites and Spontaneous Bacterial Peritonitis Vicente Arroyo Miguel Navasa

Key Concepts z

The most common cause of ascites in humans is cirrhosis followed by congestive heart failure, malignant ascites, and tuberculous peritonitis. Measurement of serum to ascitic fluid gradient of albumin and the concentration of leukocytes, standard cytologic examination for malignant cells, measurement of the concentration of adenosine deaminase, and the detection of deoxyribonucleic acid of Mycobacterium organisms by means of polymerase chain reaction of ascitic fluid are the specific tests for the differential diagnosis of the causes of ascites. However, investigation of physical and exploratory findings characteristic of these entities are also important in making the diagnosis.

z

In cirrhosis the ascitic fluid protein concentration is considerably lower than the plasma protein concentration. This is due to the capillarization of the hepatic sinusoids, which reduces their permeability to plasma proteins, and to a major contribution of the splanchnic microcirculation (with low permeability to proteins) to the formation of ascites. The concentration of proteins in ascitic fluid in cirrhosis correlates inversely with the degree of portal hypertension.

z

Lymph formation within the liver and the splanchnic circulation is markedly increased in patients with nonascitic cirrhosis who have portal hypertension. Lymph is effectively transported into the systemic circulation through the splanchnic lymphatic system and thoracic duct. Ascites develops when lymph formation overcomes the transport capacity of the lymphatic system. In the splanchnic organs (e.g., intestines, stomach, peritoneum) the increased lymph formation is more related to an increased blood inflow into the splanchnic microcirculation secondary to an arterial vasodilatation, which leads to an increase in capillary pressure and permeability, than to a backward transmission of the increased portal venous pressure into the splanchnic capillaries. The mechanism of the splanchnic arterial vasodilatation in cirrhosis is related to portal hypertension, which increases local production of vasodilatory substances, particularly nitric oxide.

z

Splanchnic arterial vasodilatation is the key mechanism of ascites formation (forward theory of ascites). In addition to increasing lymph formation in the splanchnic microcirculation, splanchnic arterial vasodilatation impairs arterial circulatory function and leads to the activation of the renin–

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aldosterone system, sympathetic nervous system, and antidiuretic hormone and renal sodium and water retention. The simultaneous occurrence of excessive lymph formation and renal retention of fluid lead to continuous ascites formation. z

There is an alteration in cardiac function in cirrhosis that could also contribute to the pathogenesis of the circulatory and renal dysfunction and to the formation of ascites. Although higher than normal in most patients, cardiac output decreases during the course of decompensated cirrhosis despite the reduction in peripheral vascular resistance. On the other hand, the heart rate does not increase in response to the progressive stimulation of the sympathetic nervous system, indicating impairment of cardiac chronotropic function.

z

Moderate sodium restriction (90 mmol/day), spironolactone, and furosemide are the basis of the medical management of ascites. Spironolactone is the principal drug. Furosemide can be added to spironolactone to increase diuretic response. Medical treatment is indicated in patients with moderate ascites.

z

Therapeutic paracentesis with intravenous administration of albumin (8 g/L of ascitic fluid removed) is the treatment of choice for tense ascites in cirrhosis. Sodium restriction and diuretics should be used to prevent the reaccumulation of ascitic fluid. Large-volume paracentesis without plasma volume expansion frequently impairs circulatory function, which although asymptomatic can adversely influence the clinical course.

z

Peritoneovenous shunting and transjugular intrahepatic portacaval shunting are effective therapies for refractory ascites in cirrhosis. They are, however, associated with a high rate of complications, particularly shunt obstruction, and do not improve the overall results of paracentesis in relation to the duration of hospitalization and survival. The recent introduction of covered stents with less rate of shunt obstruction will probably increase the indication of transjugular intrahepatic portacaval shunting in patients with refractory ascites.

z

Spontaneous infection of the ascitic fluid (spontaneous bacterial peritonitis) is a frequent event in cirrhosis (10% to 30% prevalence in patients admitted to hospital with ascites). Its pathogenesis is multifactorial, including translocation of bacteria from the intestinal lumen into the circulation, impaired reticuloendothelial system phagocytic activity leading to sustained bacteremia, and decreased antibacterial activity of the ascitic fluid. The most important predictive factor of spontaneous bacterial peritonitis is a low ascitic fluid protein concentration (250 cells/mm 3 ). Leukocyte esterase reagent strips are useful for a rapid bedside diagnosis of spontaneous bacterial peritonitis. Cultures of ascitic fluid and/or blood cultures are positive in approximately 50% of cases. The organism most commonly isolated in spontaneous bacterial peritonitis is Escherichia coli.

z

Third-generation cephalosporins are the best antibiotics for the empiric management of spontaneous bacterial peritonitis. The rate of resolution of the infection is more than 90%. However, despite rapid resolution of the infection, 30% of patients die during hospitalization.

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z

The most common cause of death in patients with spontaneous bacterial peritonitis is a multiorgan failure secondary to severe impairment of circulatory function. It is characterized by intense reduction of the cardiac output; aggravation of splanchnic arterial vasodilatation and portal hypertension; severe impairment of renal, hepatic and cerebral function; and a relative adrenal insufficiency. Circulatory support with intravenous administration of albumin at the time of diagnosis of infection reduces hospital mortality by 60%.

z

The probability of recurrence of spontaneous bacterial peritonitis is extremely high (>60% at 1 year). Antibiotic prophylaxis with oral norfloxacin drastically reduces the rate of recurrence of spontaneous bacterial peritonitis. Norfloxacin is also used for primary prophylaxis of bacterial infection in the care of patients with cirrhosis and gastrointestinal hemorrhage and of those with ascites who are at high risk for a first episode of spontaneous bacterial peritonitis (patients with advanced liver disease and low ascitic fluid protein concentration).

z

Spontaneous bacterial peritonitis caused by quinolone-resistant bacteria is emerging as a clinical problem.

P.528 P.529 Ascites is the most common complication in patients with cirrhosis. It develops as a consequence of a severe impairment of liver function and portal hypertension, and, not surprisingly, it is associated with a poor prognosis. Great advances have been made in the pathogenesis and management of cirrhotic ascites. It is now evident that ascites formation in cirrhosis cannot be considered as a consequence of “backward” transmission of the increased intrahepatic hydrostatic pressure into the hepatic and splanchnic microcirculation and a decrease in intravascular oncotic pressure because of the impaired hepatic synthesis of albumin. Ascites formation is related more to events occurring in the arterial vascular compartment and in the kidneys than to those occurring in the portal venous system. The central event of ascites formation in cirrhosis is a splanchnic arterial vasodilatation secondary to portal hypertension. It simultaneously induces two different types of events: (a) A “forward” increase in capillary pressure because of a great inflow of blood at high pressure into the splanchnic microcirculation, which favors the leakage of fluid into the peritoneal cavity (1,2), and (b) impairment of systemic hemodynamics and renal function, which leads to sodium and water retention. The recent demonstration that cardiac output decreases during the course of cirrhosis in parallel with the progression of the splanchnic arterial vasodilatation (3) adds a new dimension to the complexity of the pathogenesis of circulatory dysfunction and ascites in chronic liver diseases. These new concepts in the pathogenesis of ascites are important for a better understanding of several events occurring in patients with cirrhosis and ascites. Most important, they are the basis for the design of new treatments in these patients. For example, it is now well known that the systemic circulation is extremely unstable in patients with decompensated cirrhosis because of the resistance of the splanchnic arterial vascular compartment to the effect of endogenous vasoconstrictors (e.g., norepinephrine or angiotensin II). Therefore, the regulation of arterial blood pressure largely depends on the effect of these substances on the renal circulation. This explains why patients with cirrhosis and ascites are predisposed to the development of renal vasoconstriction and

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hepatorenal syndrome (HRS) (4). HRS may develop spontaneously; however, it most commonly occurs in close chronologic relationship with an event that increases arterial vasodilatation and decreases cardiac function (e.g., therapeutic paracentesis or spontaneous bacterial peritonitis [SBP]) (5). The recent demonstration that HRS in cirrhosis can be successfully treated by the administration of vasoconstrictor agents associated with plasma volume expansion is the most outstanding consequence of the new concept of the circulatory dysfunction associated with ascites (6,7). The introduction of the transjugular intrahepatic portacaval shunt (TIPS) and the progressive abandonment of the peritoneovenous shunting for the treatment of refractory ascites are the most relevant changes in therapy during the last decade (8,9). During this period, the important role of paracentesis in the management of patients with cirrhosis and tense ascites was clearly established (10). Also, the initial studies on a new family of drugs, the aquaretic V2 antagonists, was performed in patients with cirrhosis and ascites (11,12). These agents, by inhibiting the renal tubular effect of antidiuretic hormone, increase diuresis without affecting sodium excretion. The net effect is an increase in free water excretion and, in patients with hyponatremia, normalization of serum sodium concentration. SBP, the spontaneous infection of ascitic fluid, is the clinical condition in hepatology with the most impressive improvement in prognosis. The hospital mortality rate has decreased from 80% in the early 1970s to 10% in the last randomized controlled trial published in 2000 (13). An early diagnosis and the use of effective non-nephrotoxic antibiotics were the initial factors improving prognosis. In this regard, the recent observation that leukocyte esterase reagent strips are P.530 very sensitive and specific for the diagnosis of SBP will facilitate its rapid diagnosis at the bedside and an earlier treatment (14,15,16,17). For many years the hospital mortality rate associated with SBP ranged between 30% and 40% despite the resolution of the infection in more than 90% of the patients. Studies showing that SBP induces a deterioration of circulatory function, which may not be reversible after resolution of the infection and causes multiorgan failure, are essential to the understanding that circulatory support is important in patients with SBP (3,5,18,19). Subsequently, a randomized controlled trial clearly demonstrated that energetic plasma volume expansion with albumin at the time of diagnosis of the infection markedly reduces the incidence of circulatory and renal dysfunction and hospital mortality in patients with SBP (13). This positive finding, however, is counterbalanced by recent observations of patients with quinolone and trimethoprim–sulfamethoxazole–resistant SBP suggesting that these antibiotics are at present not as effective in the prophylaxis of SBP as it was reported in the past. The aim of the current chapter is to review the pathogenesis, diagnosis, and treatment of ascites and SBP. Particular attention has been paid to these new advances in the field. Classical well-established concepts are more briefly summarized. The reader is referred to Chapter 17 for a better understanding of some aspects of the current chapter.

Ascites Clinical Aspects

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Etiology Many diseases can lead to the accumulation of fluid within the peritoneal cavity. They can be grouped into two major categories depending on whether they directly affect the peritoneum (Table 19.1). In the first category, ascites forms as a consequence of primary or secondary peritoneal disease (e.g., tuberculous, fungal, parasitic, and granulomatous peritonitis; vasculitis; eosinophilic gastroenteritis; Whipple's disease; and primary or metastatic peritoneal tumor). The second category includes diseases causing sinusoidal portal hypertension (e.g., cirrhosis, acute alcoholic hepatitis, fulminant or subacute viral or toxic hepatitis, Budd-Chiari syndrome, hepatic veno-occlusive disease, congestive heart failure, constrictive pericarditis, and inferior vena caval obstruction over the liver) and hypoalbuminemia (e.g., nephrotic syndrome, protein-losing enteropathy, and malnutrition), and a variety of disorders that may cause ascites by different mechanisms (e.g., myxedema, benign and malignant ovarian tumors, ovarian hyperstimulation syndrome, pancreatitis, biliary tract leakage, chronic renal failure, and diseases affecting the lymphatic system of the splanchnic area). The common feature of all these diseases is that the peritoneum is not affected. By far the most P.531 frequent cause of ascites is hepatic cirrhosis followed by neoplasm. Other relatively frequent causes are congestive heart failure and tuberculous peritonitis. These four conditions account for more than 90% of ascites in Europe and North America.

Table 19.1. Causes of Ascites

PORTAL HYPERTENSION Cirrhosis Alcoholic hepatitis Fulminant hepatitis Subacute hepatitis Hepatic veno-occlusive disease Massive liver metastasis Congestive heart failure Constrictive pericarditis Budd-Chiari syndrome MISCELLANEOUS DISORDERS Myxedema Ovarian disease Carcinoma Benign tumors Ovarian hyperstimulation syndrome Pancreatic ascites Bile ascites Chylous ascites Nephrogenic ascites Acquired immunodeficiency syndrome HYPOALBUMINEMIA Nephrotic syndrome

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Protein-losing enteropathy Malnutrition PERITONEAL DISEASES Malignant ascites Peritoneal mesothelioma Peritoneal carcinomatosis Infectious peritonitis Tuberculosis Chlamydia trachomatis Fungal and parasitic peritonitis Candida albicans Histoplasma capsulatum Coccidioides immitis Cryptococcus neoformans Schistosoma mansoni Strongyloides stercoralis Entamoeba histolytica Other peritoneal diseases Sarcoidosis Starch granulomatous peritonitis Barium peritonitis Vasculitis Systemic lupus erythematosus Henoch-Schönlein purpura Eosinophilic gastroenteritis Whipple's disease

Detection of ascites The diagnosis of ascites is simple when large amounts of fluid accumulate in the abdominal cavity. However, diagnosis can be difficult when the volume of ascitic fluid is small or if the patient is obese. In these circumstances, ultrasonography is the best method for the detection of ascites because it is not expensive and gives information about the liver and other intra-abdominal organs. Ascites due to portal hypertension characteristically appears as homogeneous, echo-free areas surrounding and interposed between the loops of bowel and viscera in a relatively uniform manner. When the amount of ascites is small, the fluid tends to collect in the flanks and the superior right paracolic gutter, around the liver, and in the lower peritoneal reflection in the pelvis. Atypical sonographic characteristics, such as the presence of multiple echoes, septations or fibrous strands within the ascitic fluid, and loculation of fluid, are highly suggestive of an ascites unrelated to portal hypertension. The sonographic characteristics of the liver, suprahepatic veins, portal venous system, peritoneum, spleen, stomach, intestine, and intra-abdominal lymphatic nodes, are of great help in assessing the etiology of ascites.

Characteristics of cirrhotic ascites The biochemical and cytologic characteristics of the ascitic fluid provide important information for the differential diagnosis. The ascitic fluid in cirrhosis

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is characteristically transparent and yellow/amber in color. In most patients (70%) the total protein concentration is lower than 2.5 g/dL and approximately 50% correspond to albumin. The total protein concentration in ascitic fluid correlates inversely with portal pressure. It decreases during the course of the disease as portal hypertension increases (20,21). SBP characteristically develops in patients with a low total protein concentration in ascitic fluid (0.50) occurs in 2% of patients. In some cases, bloody ascites is secondary to a superimposed superficial hepatocellular carcinoma bleeding into the peritoneal cavity. In most cases no apparent cause can be detected. Because hepatic and thoracic lymph is often bloody in cirrhosis, bloody ascites can be caused by leakage of bloody lymph into the abdominal cavity. Ascites in cirrhosis has traditionally been considered an inert fluid mainly composed of water, electrolytes, and proteins that transudates passively from the microvascular compartment into the peritoneal cavity. At present, there is evidence that many metabolic reactions and synthetic processes occur within the ascitic fluid. For example, in patients with cirrhosis a complex coagulation process within the ascitic fluid results in intraperitoneal coagulation and primary and secondary fibrinolysis. The macrophages of ascitic fluid synthesize vasodilatatory substances (e.g., nitric oxide, adrenomedullin, vascular endothelial growth factor), a feature not observed in their precursors, the circulating monocytes (23). The pathophysiologic significance of this finding is unknown. It is also unknown whether this reflects a generalized activation of the peritoneal macrophages or a local activation by some factor within the ascitic fluid (e.g., an endotoxin). The concentration of interleukin-6 and tumor necrosis factor is higher in ascites than in plasma, indicating a local production of cytokines (19). Also, the concentration of leptin and vascular endothelial growth factor is higher in ascitic fluid than in plasma (24,25). The angiogenic activity of the ascitic fluid of patients with cirrhosis may be related to this feature (26). Finally, the ascitic fluid has antibacterial activity, which correlates directly with the total ascitic fluid protein concentration (21). Substances such as complement, fibronectin, cytokines, and nitric oxide are implicated in this effect, which may be an important defensive mechanism against SBP. Not surprisingly, the infusion of ascitic fluid within the general circulation is associated with important biologic effects, the most important being intravascular coagulation and fever.

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Differential diagnosis of cirrhotic ascites and other types of ascites Malignant ascites is macroscopically bloody in only 10% of patients. Differentiation from cirrhotic ascites P.532 is based mainly on the characteristics of the ascitic fluid and on additional diagnostic findings. The total ascitic protein concentration is over 3.0 g/dL in most patients with malignant ascites. The serum to ascitic fluid gradient of albumin (usually 3 g/dL) and lymphocytes. However, in cirrhosis with ascites and tuberculous peritonitis the ascitic fluid may be a transudate. The concentration of adenosine deaminase, an enzyme that participates in the proliferation and differentiation of lymphocytes, is increased in tuberculous pleural effusions and ascitic fluid in tuberculous peritonitis. It has been reported, however, that the percentage of false-negative results in tuberculous peritonitis is high in the presence of cirrhosis (28). The diagnosis of tuberculous peritonitis cannot be based on cultures of ascitic fluid because the usual techniques of culturing acid-fast bacilli requires several weeks of incubation and frequently gives false-negative results (21). On the other hand, although it has been suggested that the proportion of positive culture results may be as high as 80% when 1L of ascitic fluid is concentrated by means of centrifugation, the proportion reported in most studies is much lower. The detection of deoxyribonucleic acid (DNA) of Mycobacterium tuberculosis by means of polymerase chain reaction (PCR) assay of ascitic fluid is rapid and appears to be as sensitive as culture. False-negative results, however, have been reported, justifying the administration of antituberculosis treatment in patients with clinical and histologic features characteristic of peritoneal tuberculosis, even in cases with negative results from culture and PCR analysis. Laparoscopy and direct biopsy of the affected areas is required for the diagnostic confirmation and differentiation from other conditions causing granulomatous peritonitis (e.g., sarcoidosis, Crohn's disease). Chylous ascites consists of a macroscopically turbid and milky ascites caused by a high concentration of chylomicrons rich in triglycerides (29). The principal causes of chylous ascites in adults are primary abnormalities of the lymphatic vessels (lymphangiectasia) and obstruction of the lymphatic system by neoplasms, particularly lymphoma. Chylous ascites should be differentiated from

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pseudochylous ascites, in which, although the macroscopic appearance is identical, the triglyceride concentration is less than 110 mg/dL (the diagnostic cutoff for chylous ascites). Cirrhosis is an infrequent cause of chylous ascites that is usually related to hydrostatic hypertension within the splanchnic lymph vessels, which can lead to spontaneous rupture of some of these vessels into the abdominal cavity. Other causes of chylous ascites are surgical procedures involving the retroperitoneal region (including splenorenal shunt), pancreatitis, sarcoidosis, tuberculosis, and abdominal trauma. Biliary and pancreatic ascites are caused by leakage of bile and pancreatic fluid, respectively, into the abdominal cavity. In biliary ascites, paracentesis yields a green ascitic fluid with a concentration of bilirubin considerably higher than that in plasma. Although bile leakage into the abdominal cavity can induce signs and symptoms of biliary peritonitis, some patients have no symptoms other than the accumulation of a large amount of biliary ascitic fluid. Therefore, biliary ascites should be considered a possible diagnosis when any patient accumulates intraabdominal fluid after liver biopsy or biliary surgery (30). Pancreatic ascitic fluid is usually an exudate (ascitic fluid protein concentration is generally >3 g/dL), contains very high concentrations of pancreatic enzymes, and is mainly secondary to chronic pancreatitis. Because most patients with this disorder have alcoholism and may have massive ascites with little or no abdominal pain, the differential diagnosis of pancreatic from cirrhotic ascites can be difficult on clinical grounds (24).

Peripheral edema and cirrhotic hydrothorax Edema in the lower extremities is frequent in patients with cirrhosis. In many cases it precedes the development of ascites by weeks or months. It can also appear simultaneously with the onset of ascites, or weeks or months thereafter. Hypoalbuminemia and increased venous pressure in the lower extremities due to constriction of the intrahepatic segment of the inferior vena cava or due to the high intra-abdominal pressure caused by the presence of ascites have been proposed as possible mechanisms. Massive peripheral edema with minimal or no ascites is found in patients with cirrhosis having severe hepatic insufficiency and low portal hypertension from TIPS insertion. Five percent patients with cirrhosis have pleural effusion in the absence of pulmonary or pleural diseases or any other potential cause of hydrothorax. Clinical ascites is almost always evident, and the pleural effusion is usually right sided. The mechanism of this cirrhotic hydrothorax in most cases is the direct passage of ascites through defects in the diaphragm into the pleural space. The driving force is the hydrostatic gradient between the positive intra-abdominal pressure and the negative intrathoracic pressure. In cases of cirrhotic hydrothorax without detectable abdominal ascites (thoracic ascites) the passage of fluid into the pleural cavity probably equals the rate of ascites formation. Because ascites and the pleural fluid of cirrhotic hydrothorax have the same origin, a different cause of pleural effusion should be suspected if marked differences in biochemical and cytologic characteristics are observed between both fluids. Because cirrhotic hydrothorax occurs with abdominal ascites, patients with this condition may P.534 contract spontaneous infection of the pleural fluid (spontaneous bacterial empyema) (31).

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Local Intra-Abdominal Factors in the Formation of Ascites Portal hypertension and leakage of fluid from the intravascular compartment to the peritoneal cavity There is substantial evidence that severe portal hypertension is the main disorder in the formation of ascites in cirrhosis. Patients have significantly higher portal pressure than those without ascites (Fig. 19.2). Ascites develops only when the hepatic venous pressure gradient (an estimation of the intrahepatic vascular resistance) is more than 12 mm Hg. Ascites is unusual in patients treated with a surgical side-to-side or end-to-side portacaval shunt for bleeding varices. In patients treated by TIPS, ascites frequently disappears after insertion of the stent and reappears if there is malfunction of the shunt. Ascites is a frequent complication of diseases associated with increased hydrostatic pressure in the hepatic sinusoids (diseases that cause postsinusoidal blockage of the hepatic blood flow such as pericarditis, congestive heart failure, suprahepatic vena caval obstruction, Budd-Chiari syndrome, and hepatic venoocclusive disease) and of those in which the blockade of the hepatic blood flow occurs mainly at the sinusoidal level (e.g., cirrhosis, severe acute alcoholic hepatitis, and fulminant or subacute toxic or viral hepatitis). Ascites is unusual in diseases associated with intrahepatic or extrahepatic presinusoidal portal hypertension. On the basis of these features and the results of early experimental studies, it has been traditionally considered that ascites is derived mainly from the hepatic microcirculation. Although differences in permeability characteristics between the hepatic and the splanchnic peritoneal (gastric and intestinal) microcirculation also support this concept, recent data suggest that ascites in cirrhosis is derived from both the hepatic and the splanchnic microcirculation (1).

▪ Figure 19.2 Wedged hepatic venous pressure in patients with compensated cirrhosis (no ascites) and in those with ascites and moderated and marked sodium retention. (From Bosch J, Arroyo V, Betriu A, et al. Hepatic hemodynamics and the renin-angiotensin system in cirrhosis. Gastroenterology 1980;78:92–99, with permission.)

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Transmicrovascular fluid exchange in postsinusoidal and prehepatic portal hypertension The hepatic sinusoids do not have basement membranes. They are lined only by endothelial cells, Kupffer cells, and stellate (fat-storing or Ito) cells. The endothelial cells are by far the main component of the sinusoidal wall. Kupffer cells also contribute to the sinusoidal wall, although they are most often within the sinusoidal lumen attached by processes to the endothelial cells. The endothelial cells form a porous sinusoidal wall, with apertures ranging between 100 and 500 nm in radius (Fig. 19.3). Microvilli from the hepatocytes cross the space of Disse and pass through these pores to reach the sinusoidal lumen. Stellate cells, together with few collagen fibers and other particles, are mainly located in the space of Disse. Under normal conditions this is an inconspicuous space in free communication with the interstitial space of the portal and central venous area, where there are terminal lymphatic vessels. The characteristics of the sinusoidal wall explain why, in the normal liver, the concentration of proteins in the hepatic lymph is approximately 90% of that in plasma. P.535 The trans-sinusoidal oncotic gradient in the microcirculation of a normal liver, therefore, is very low. In contrast, the splanchnic capillaries are much less porous (the estimated pore size is 50 to 100 times less than that of the hepatic sinusoids) and have a basement membrane. Not surprisingly, the concentration of protein is lower in the splanchnic than in the hepatic lymph (lymph to plasma ratio of proteins is 0.50 in the intestinal lymph vs. 0.85 in the hepatic lymph) (1,32,33).

▪ Figure 19.3 Normal hepatic sinusoid in rat liver. The fenestrae are regularly distributed in the sieve plates, which are separated by intervening cytoplasmic processes. H, hepatocyte; SD, space of Disse. (From MacSween RNM, Scothorne RJ. Developmental anatomy and normal structure. In: MacSween RNM, Anthony PP, Scheuer PJ, et al. eds. Pathology of the liver,

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3rd Ed. New York: Churchill Livingstone, 2002:1–66, with permission.)

There are other marked differences between the hepatic and the splanchnic microcirculation. First, capillary pressure is autoregulated in the splanchnic circulation but not in the liver. The acute increase in pressure in the hepatic veins (e.g., after the constriction of the suprahepatic vena cava or the hepatic veins) is almost completely transmitted back into the hepatic sinusoids. In addition, the increase in pressure is associated with an increase in filtration coefficient in the sinusoids and, therefore, in the permeability to proteins (1,32,33). In contrast, only 60% of the acute increase in portal venous pressure is transmitted back to the capillary bed of the small and large intestines and is associated with a decreased filtration coefficient. These effects represent a myogenic constriction of the arteriolar resistance and precapillary sphincters, which reduces microvascular pressure and the number of perfused capillaries. Second, the compliance (relation between interstitial pressure and interstitial volume) is much lower in the liver than in the intestine. Finally, the intestines, but not the liver, have an efficient lymphatic system for removing interstitial edema (1,32,33). These differences between the hepatic and splanchnic microcirculation explain the findings observed in experimental animals after constriction of the suprahepatic vena cava or hepatic veins and partial ligation of the portal vein. Elevation of hepatic venous pressure is associated with a dramatic increase in the passage of fluid, with a protein concentration similar to that in the plasma from the sinusoidal lumen to the space of Disse. The macroscopic consequence of this is a marked enlargement of the liver. Because the compliance of the liver is low and the ability of the lymphatic system to remove the interstitial fluid insufficient, a marked increase in interstitial pressure ensues. This leads to leakage of hepatic lymph with very high protein concentration from the liver surface into the peritoneal cavity. This sequence of events probably occurs in Budd-Chiari syndrome and other clinical forms of suprahepatic portal hypertension, in which there is hepatomegaly as well as protein-rich ascites formation. The elevation in portal venous pressure (e.g., after partial ligation of the portal vein) increases the formation of lymph with low protein concentration from the stomach, small intestine, and colon and is associated with local edema in these organs. However, there is no leakage of fluid into the abdominal cavity probably because of two factors. First, the acute increase in filtration is rapidly counterbalanced by an increase in the oncotic pressure difference between the capillary lumen and interstitial space, which limits the exit of fluid from the intravascular compartment. Second, the splanchnic lymphatic system is able to return most of the excess of lymph produced in the stomach and intestines to systemic circulation. Interestingly enough, and contrary to the process occurring in the normal liver in which an increase in hepatic venous pressure is associated with an increase in the lymph to plasma protein ratio to almost 1, in the intestine the increase in portal pressure decreases the lymph to plasma protein ratio to 0.20 (34,35).

Transvascular exchange of fluid and source of ascites in cirrhosis The hepatic and the splanchnic transvascular exchange of fluid in cirrhosis differs

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considerably from that in postsinusoidal and prehepatic portal hypertension. This is due to anatomic and functional changes occurring in the hepatic and splanchnic microcirculation during the course of cirrhosis. In the hepatic microcirculation there is a “capillarization” of the sinusoids, which means that the normal sinusoids become microvessels with continuous endothelial lining, lacking fenestra and supported by a basement membrane and collagenous tissue (33) (Fig. 19.4). This capillary-like structure and the sinusoidal structures are encountered in sequence in the same vascular pathway, the P.536 former being more commonly found at the periphery of the regenerative nodules. The degree of capillarization of the hepatic sinusoids, and, therefore, the permeability to albumin in the hepatic microcirculation, varies greatly from patient to patient. For example, whereas the volume of distribution of albumin in the normal liver exceeds that of red blood cells by 60% because of the passage of albumin but not cells into the space of Disse, in cirrhotic livers it may be as low as 5%, indicating a microcirculation almost totally impermeable to albumin (33). In some cirrhotic livers, however, this percentage may approach that found in normal livers. Not surprisingly, the hepatic lymph to plasma ratio for total proteins in cirrhosis ranges between 0.07 and 0.60 (mean value 0.50).

▪ Figure 19.4 Capillarization of sinusoids in hepatic cirrhosis. An electron micrograph in which a capillary is seen between regenerative liver parenchymal cells. The capillary lumen (C) is separated from the liver cells (L) by the nonfenestrated endothelial cell, a basement membrane, and a layer of fibrillary collagen. (From Huet P-M, Goresky CA, Villeneuve JP, et al. Assessment of liver microcirculation in human cirrhosis. J Clin Invest 1982;70:1234–1244, with permission.)

In cirrhotic portal hypertension there is no autoregulation of capillary pressure and filtration coefficient in the splanchnic microcirculation. Instead of inducing a splanchnic vasoconstriction, portal hypertension in cirrhosis is associated with generalized splanchnic arterial vasodilatation (32). The increase in hydrostatic pressure in the splanchnic capillaries in cirrhosis is due to both a “backward” transmission of the increased portal pressure into the splanchnic microcirculation and a “forward” transmission of the high pressure in the arterial vascular

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compartment to the splanchnic capillaries due to the decreased arterial vascular resistance (1). Results of experimental studies indicate that by far the most important mechanism of the increased hydrostatic pressure in the splanchnic microcirculation in portal hypertension is the reduction in arterial vascular resistance and, consequently, the increased inflow of blood at high pressure to this compartment (Fig. 19.5). This increase in hydrostatic pressure leads to a fall in lymph to plasma ratio of protein (0.20 vs. 0.50 to 0.60 in normal conditions). Not surprisingly, interstitial edema in the intestinal mucosal, muscular, and serosal layers is prominent in cirrhosis among humans.

▪ Figure 19.5 Portal vein pressure, portal blood flow, intestinal capillary pressure and intestinal lymph flow in control and in acute and chronic portal hypertensive rats. *, P < 0.05 versus control; **, P < 0.01 versus 0.04. (From Korthuis RJ, Kinden DA, Brimer GE, et al. Intestinal capillary filtration in acute and chronic portal hypertension, Am J Physiol 1988;254:G339– G345, with permission.)

Vessels leaving the liver by the hilum principally drain liver lymph. Liver lymph, as well as that derived from other intra-abdominal organs (e.g., pancreas, spleen, stomach, large and small intestines and mesentery), drains into the thoracic duct. The thoracic duct is a 35- to 45-cm long lymphatic channel that begins in the upper lumbar region, passes through the diaphragm, ascends in the posterior mediastinum, and drains into the left subclavian or internal jugular vein. In healthy humans, thoracic duct lymph flow is approximately 1L/day. In cirrhosis it averages 8 to 9 L/day, and may be higher than 20 L/day, indicating a high filtration of fluid from the hepatic and splanchnic intravascular compartment into the interstitial space (35). There is evidence that the lymphatic system is efficient in returning most of this fluid into the intravascular compartment in patients with cirrhosis and ascites. Less than 5% of the albumin leaving the intravascular compartment (an estimation of the dynamic of fluid through the

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sinusoids and splanchnic capillaries) escapes into the peritoneal cavity (34). Ascites formation in cirrhosis is therefore the consequence of a small spillover of the increased hepatic and splanchnic lymph formation, most of which is returned directly to the circulation through the lymphatic system. P.537 The source of ascites in cirrhosis has never been specifically investigated. The traditional concept that ascites in cirrhosis is derived mainly from the hepatic vascular compartment is not in agreement with the data presented earlier. The total concentration of protein in ascitic fluid and thoracic duct lymph in most patients with cirrhosis is lower than that in the hepatic lymph. This finding indicates a significant contribution of the splanchnic organs to the formation of ascites. In patients with advanced decompensated cirrhosis, severe portal hypertension, intense splanchnic arterial vasodilatation, and very low total protein concentration in ascitic fluid, most cases of ascites are probably the result of intestinal (and filtration by other splanchnic organs) filtration.

Reabsorption of ascitic fluid The volume of ascites depends not only on the amount of hepatic and splanchnic interstitial fluid leaking into the peritoneal cavity but also on the rate of reabsorption of ascitic fluid into the intravascular compartment. The lymphatic vessels on the undersurface of the diaphragm play an important role in this latter process. These vessels and the diaphragmatic peritoneum are especially prepared for this function. A single layer of mesothelial cells covers the peritoneal surface of the diaphragm over a connective tissue matrix with a very rich plexus of terminal lymphatic vessels (lymphatic lacunae) (36,37,38). The submesothelial connective tissue over the lymphatic lacunae is almost absent and wide gaps, large enough to allow the passage of erythrocytes, connect the peritoneal cavity with the lumen of the terminal lymphatics. The submesothelial lymphatic plexus drains into a deeper plexus of valved collecting vessels, which penetrates connecting tissue septa between the muscular fibers of the diaphragm and drain into parasternal trunks on the ventral thoracic wall, right lymphatic duct, and right subclavian or internal jugular vein. During inspiration, intercellular gaps close, intraperitoneal pressure increases, and the lacunae are emptied through the combined effects of local compression, increased intra-abdominal pressure, and reduced intrathoracic pressure. During expiration, the gaps open and free communication is reestablished.

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▪ Figure 19.6 Sodium excretion, free water clearance, and glomerular filtration rate (GFR) in a large series of patients with cirrhosis and ascites. Shadowed areas indicate normal values in healthy subjects. Measurements of sodium excretion in healthy subjects and patients with cirrhosis were done under conditions of sodium restriction (50 mEq/day). Free water clearance was measured after an intravenous water load of 20 mg/kg body weight (5% dextrose solution).

Reabsorption of ascites in cirrhosis is a rate-limited process. The estimated mean rate of ascitic fluid reabsorption is 1.4 L/day, ranging from less than 0.5L to more than 4L. The low rates of ascites formation and reabsorption do not mean that the intraperitoneal cavity is almost isolated from the rest of the body. The transperitoneal exchange of water and water-soluble substances (e.g., antibiotics not bound to proteins) by diffusion is rapid in patients with cirrhosis and ascites.

Renal and Circulatory Dysfunction: Role in the Formation of Ascites Renal dysfunction in cirrhosis Renal sodium retention, as well as the secondary retention of water, is the second important factor in the formation of ascites (Fig. 19.6). The mechanism of P.538 this abnormality is multifactorial. The renin–angiotensin–aldosterone system, which stimulates sodium reabsorption in the distal nephron, and the sympathetic nervous system, which increases sodium reabsorption in the proximal tubule, loop of Henle, and distal tubule, are stimulated in a significant number of patients with cirrhosis and ascites but not in those with compensated cirrhosis (Fig. 19.7). Glomerular filtration rate (GFR) is markedly reduced in some patients with decompensated cirrhosis and may contribute to sodium retention. However, 30% of patients with cirrhosis, sodium retention, and ascites show plasma concentration of aldosterone and norepinephrine (a sensitive marker of the

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sympathetic nervous activity) and GFR within normal limits. This finding indicates that other, still unknown mechanisms participate in the pathogenesis of sodium retention in cirrhosis. The circulating plasma levels of natriuretic peptides (i.e., atrial natriuretic peptide, brain natriuretic peptide) (39) are markedly increased in patients with decompensated cirrhosis. Therefore, sodium retention occurs despite an increased synthesis of these endogenous natriuretic hormones.

▪ Figure 19.7 Aldosterone and norepinephrine levels in healthy subjects (I), compensated patients with cirrhosis (II), and patients with cirrhosis and ascites (III). (From Arroyo V, Planas R, Gaya J, et al. Sympathetic nervous activity, renin-angiotensin system and excretion of prostaglandin E2 in cirrhosis. Relationship to functional renal failure and sodium and water excretion. Eur J Clin Invest 1983;13;271–278, with permission.)

As decompensated liver diseases progresses, patients develop a decreased renal ability to excrete free water. When this function is severely depressed, patients become unable to excrete the excess of water ingested with the diet. This water dilutes the interior milieu and produces hyponatremia and hypo-osmolality. Water retention and dilutional hyponatremia develop months after the onset of sodium retention and ascites and are secondary to a nonosmotic hypersecretion of antidiuretic hormone (Fig. 19.8). Water retention in patients with dilutional hyponatremia is a part of the positive fluid balance and contributes to the formation of ascites. At the terminal stage of the disease patients have HRS (4). This is a functional renal failure due to an intense vasoconstriction of the renal arteries, which causes a decrease in renal perfusion and GFR. Two types of HRS have been identified (Fig. 19.9). Type 2 HRS involves a moderate renal failure (serum creatinine between 1.5 and 2.5 mg/dL; upper normal level 1.2 mg/dL) that P.539 remains steady during relatively long periods (months). Type 1 HRS is a rapidly progressive renal failure. It usually develops in patients who already have type 2 HRS in close chronologic relation to a precipitating event, such as bacterial

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infection, gastrointestinal hemorrhage, or major surgical procedure. In type 1 HRS, the serum creatinine level can become very high (>4 to 5 mg/dL) in a short period (days or weeks). The prognosis of patients with type 1 HRS is extremely poor (80% of patients die within 1 month of the onset of the syndrome).

▪ Figure 19.8 Antidiuretic hormone (ADH) levels in healthy subjects and in patients with cirrhosis and ascites after water restriction (A) and after water loading (B). Patients with cirrhosis and ascites are divided into two groups: Those with positive free water clearance after a water load (20 mL/kg of body weight) (middle graph) and those with negative free water clearance and dilutional hyponatremia. There was an inverse relationship between free water clearance and ADH. (From Pérez-Ayuso RM, Arroyo V, Camps J, et al. Evidence that renal prostaglandins are involved in renal water metabolism in cirrhosis. Kidney Int 1984;26:72–80, with permission.)

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▪ Figure 19.9 A typical patient with type 2 hepatorenal syndrome (HRS) and refractory ascites who developed type 1 HRS in close chronologic relationship with spontaneous bacterial peritonitis. Despite the rapid resolution of the infection, the patient developed a rapidly progressive renal failure and died.

Circulatory dysfunction and peripheral arterial vasodilatation in cirrhosis: Relationship with renal dysfunction and intrahepatic hemodynamics Renal dysfunction in patients with cirrhosis occurs in the setting of a circulatory dysfunction characterized by a marked arterial vasodilatation (40,41). There is evidence that the splanchnic circulation is the site of this arterial vasodilatation because there is vasoconstriction in all the other major vascular territories such as the kidneys, muscle, skin, and brain (42,43,44). In contrast, in the splanchnic circulation there is vasodilatation, which increases the inflow of blood into the portal venous system (26). Indirect evidence suggests that the degree of splanchnic arterial vasodilatation in cirrhosis with ascites is intense because the hepatic blood flow is normal although 60% to 80% of the portal flow is shunted through collateral circulation. The splanchnic arterial blood flow in cirrhosis, therefore, may be double that in healthy subjects. The splanchnic circulation is also the predominant site where arterial vasodilatation occurs in patients with compensated cirrhosis. It is well established that splanchnic arterial vasodilatation in cirrhosis is related to portal hypertension. It plays a major role in the maintenance of increased portal pressure despite the development of collateral circulation. The mechanism by which increased portal pressure decreases splanchnic arterial vascular resistance is not well understood. For many years arterial vasodilatation in cirrhosis has been attributed to increased circulating plasma levels of vasodilators such as glucagon, prostaglandins, adrenomedullin, and natriuretic peptide. However, because the site of arterial vasodilatation is the splanchnic circulation, a local mechanism (increased release of a vasodilator substance within the splanchnic area) is a more likely hypothesis. Results of recent studies suggesting that nitric oxide, a vasodilator substance that acts in a paracrine manner, is important in the pathogenesis of splanchnic arterial vasodilatation in cirrhosis is consistent with this hypothesis. Increased activity of nitric oxide synthase in the splanchnic circulation has been reported in experimental cirrhosis (45,46,47). On the other hand, inhibition of nitric oxide normalizes circulatory function in experimental cirrhosis (47). Two hypotheses have been proposed to explain the mechanism of the increased production of nitric oxide in the splanchnic circulation. The first is that it occurs secondary to bacterial translocation from the intestinal lumen to the interstitial intestinal space. Endotoxin and the increased cytokine production stimulate the activity of nitric oxide synthase in the endothelial and vascular smooth muscle cells (46,48). The second hypothesis P.540 considers that there is a stimulation of the nonadrenergic, noncholinergic nervous system secondary to portal hypertension (46,49). This is a sensitive system that, when activated, releases numerous vasodilatory neurotransmitters, including nitric oxide, calcitonin gene–related peptide, substance P, and vasoactive intestinal peptide (50,51). Nonadrenergic, noncholinergic terminals are abundant

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not only in the gastrointestinal smooth muscle but also in the vascular smooth muscle cells. It may be possible that portal hypertension induces changes in the intestinal wall (increase in interstitial pressure and interstitial edema) that stimulate this system and cause an inhibitory effect on the gastrointestinal smooth muscle cells. The gastrointestinal transit time is greatly prolonged in patients with cirrhosis; this finding indicates inhibition of gastrointestinal motility (52). The circulatory dysfunction induced by the splanchnic arterial vasodilatation is the primary mechanism implicated in the pathogenesis of complications in patients with cirrhosis. The impairment of renal function is the most characteristic complication induced by the circulatory dysfunction (Fig. 19.10). It is also the mechanism of hepatopulmonary syndrome, which is characterized by mild to severe hypoxemia in the absence of associated cardiopulmonary disease. The hypoxemia is caused by vasodilatation in the intrapulmonary circulation. Finally, although the distortion of the liver vascular architecture caused by fibrosis and nodule formation is the most important mechanism of the increased intrahepatic vascular resistance in cirrhosis, there is a functional component of portal hypertension because of an increase in the intrahepatic vascular tone. The contractile intrahepatic vascular elements include the vascular smooth muscle cells from the small venules and the hepatic stellate cells that surround the sinusoids. In cirrhosis these stellate cells undergo a phenotypic transformation, acquiring receptors for numerous endogenous vasoactive substances, including angiotensin II, norepinephrine, antidiuretic hormone, and endothelin, and contractile properties. Therefore, the circulatory dysfunction in cirrhosis and the secondary activation of these endogenous vasoactive substances may affect the functional component of the intrahepatic resistance to the portal venous flow and increase portal pressure.

▪ Figure 19.10 Peripheral arterial vasodilatation hypothesis. NO, nitric

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oxide; CGRP, calcitonin gene–related peptide; SP, substance P.

In the initial stages of cirrhosis, circulatory dysfunction is compensated by a hyperdynamic circulation (Fig. 19.11). Plasma volume, cardiac output, and heart rate increase and the circulatory transit time decreases. The splanchnic circulation behaves functionally as an arteriovenous fistula. The incidence of arterial hypertension in patients with cirrhosis and portal hypertension is very low because of this circulatory abnormality. With the progression of the liver disease and the accentuation of portal hypertension and splanchnic arterial vasodilatation, patients develop sodium retention and ascites. In the initial phases of ascites, the renin–angiotensin and the sympathetic nervous systems are not stimulated, and the mechanism of sodium retention in this period is unknown. Later during the course of the disease, the renin–angiotensin– aldosterone system and the sympathetic nervous system become progressively activated in parallel with more intense reduction in urine sodium excretion. Patients with ascites and normal plasma P.541 renin activity and aldosterone concentration, in general, have urinary sodium excretion over 10 mEq/day, and they respond easily to low diuretic dosage. In contrast, most patients with high renin and aldosterone concentration show a urinary sodium excretion lower than 5 mEq/day (in many cases, almost zero) and need high diuretic dosage to achieve a natriuretic response. Hypersecretion of antidiuretic hormone occurs at later stages of the disease. This explains why hyponatremia is a late event in decompensated cirrhosis. This is probably related to the fact that antidiuretic hormone is less sensitive than the sympathetic nervous system and the renin–angiotensin system to changes in the effective circulating blood volume. HRS develops at the very late stages of the disease, always in the setting of an intense activation of the renin–angiotensin and sympathetic nervous systems and antidiuretic hormone.

▪ Figure 19.11 Temporal relationship between the degree of splanchnic

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arterial vasodilatation and the appearance of the various disorders of renal function in cirrhosis. RAAS, renin–angiotensin–aldosterone system; ADH, antidiuretic hormone; HRS, hepatorenal syndrome. (From Arroyo V, Jimenez W. Complications of cirrhosis II. Renal and circulatory dysfunction. Lights and shadows in an important clinical problem. J Hepatol 2000;32(suppl 1):157–170, with permission.)

The administration of specific antagonists of the vascular effect of angiotensin II or antidiuretic hormone (V1 antagonists) to experimental animals or patients with cirrhosis and ascites is associated with a profound hypotensive response secondary to a decrease in peripheral vascular resistance. This effect, which is not observed in healthy persons or in patients with compensated cirrhosis (patients who have never had ascites), indicates that activation of the renin– angiotensin system, sympathetic nervous system, and antidiuretic hormone in cirrhosis with ascites is a homeostatic response to maintain arterial pressure at normal or nearly normal levels. Arterial vasodilatation and the secondary arterial hypotension are therefore stimuli leading to the activation of these systems. The different phases of cirrhosis in the development of ascites and abnormalities of renal function parallel the progression of portal hypertension and splanchnic arterial vasodilatation. In patients with cirrhosis there is a strong direct relationship between the degree of portal hypertension; plasma level of renin, aldosterone, and norepinephrine; and the intensity of sodium retention. Arterial pressure is lower in patients with cirrhosis and ascites than in those with compensated cirrhosis. Finally, among patients with ascites, those with HRS present with the lowest arterial pressure and the highest plasma levels of renin, norepinephrine, and antidiuretic hormone.

Renal and other extrasplanchnic regional circulations in cirrhosis Traditional studies with para-aminohippurate clearance and recent investigations with echo-Doppler technique have shown increased intrarenal vascular resistance in patients with cirrhosis and ascites before the development of HRS. Therefore, HRS is the extreme expression of an impairment of renal circulatory function that starts at earlier stages. Renal plasma flow, intrarenal vascular resistance, and GFR in cirrhosis with ascites closely correlate with the degree of stimulation of the renin–angiotensin system and the P.542 sympathetic nervous system (53). Patients with normal or moderately increased plasma levels of renin and norepinephrine usually show normal renal perfusion and GFR, whereas the levels of these substances are markedly increased in patients with HRS (Table 19.2). These data have led to the contention that HRS in cirrhosis is caused by renal vasoconstriction related to the activation of these systems (3). However, this hypothesis is too simple, and at present, there is evidence that intrarenal mechanisms may also participate in the regulation of renal perfusion.

Table 19.2. Mean Arterial Pressure, Plasma Volume, Cardiac Index, Plasma Renin Activity, and Norepinephrine Levels in Patients with

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Cirrhosis with and without Hepatorenal Syndrome and in Healthy Subjects

Cirrhosis with ascites Healthy subjects

No HRS

HRS

MAP (mm Hg)

87 ± 3

82 ± 2

69 ± 5

Plasma volume (mL/kg)

44 ± 2

66 ± 2

59 ± 4

3.0 ± 0.2

5.7 ±

5.5 ± 0.5

Cardiac index (L/min m 2 )

0.2

Plasma renin activity

0.5 ± 0.1

8.2 ± 2

31.7 ±

(ng/mL h)

Norepinephrine (pg/mL)

10.4

200 ± 22

512 ±

1,141 ±

39

134

P < 0.001 for all values (analysis of variance [ANOVA]). HRS, hepatorenal syndrome; MAP, mean arterial pressure.

The kidneys synthesize vasodilator substances, the most important of which are prostaglandins, particularly prostaglandin E 2 , and prostacyclin. The renal synthesis of prostaglandins increases whenever there is an increased activity of the renin–angiotensin and sympathetic nervous systems (45). Prostaglandins antagonize the vasoconstrictor effect of angiotensin II and norepinephrine and, by this mechanism, play an essential role in the maintenance of renal perfusion and GFR in conditions such as decompensated cirrhosis or congestive heart failure, in which there is circulatory dysfunction. A syndrome similar to HRS can be produced in patients with nonazotemic cirrhosis and ascites by the administration of nonsteroidal anti-inflammatory drugs, which inhibit prostaglandin synthesis (53,54). Investigations in experimental animals with cirrhosis and ascites have shown that the renal production of nitric oxide also participates in the maintenance of renal perfusion (55). Finally, the administration of antagonists of the vascular receptors of natriuretic peptides in animals with cirrhosis and ascites induces an impairment of renal function that mimics HRS (56). Therefore, intrarenal and circulating vasodilatory substances contribute to the maintenance of renal perfusion in cirrhosis with ascites. HRS develops when the renal production of these substances is insufficient to antagonize the renal effects of the endogenous vasoconstrictor systems. This can occur when there is a stimulation of the vasoconstrictor systems, a reduction in the synthesis of vasodilators, or both. Prostaglandin synthesis is initiated by the transformation of membrane

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phospholipids to arachidonic acid, a process mediated by phospholipase A 2 . Subsequently, arachidonic acid is converted into the endoperoxides prostaglandin G 2 and prostaglandin H 2 by the action of the enzyme cyclo-oxygenase (COX). Two types of COX exist, COX-1, which plays an important role in many physiologic processes including the protection of the gastric mucosa and the regulation of renal perfusion, and COX-2, which is involved in the inflammatory process. Aspirin and the traditional nonsteroidal anti-inflammatory drugs (e.g., indomethacin, ibuprofen, and diclofenac) inhibit both COX-1 and COX-2. Therefore, in addition to their anti-inflammatory effect, they may produce lesions in the gastric mucosa and, in edematous patients, renal failure. Recently, specific inhibitors of COX-2 have been developed. Studies in experimental animals with cirrhosis and ascites and a recent investigation in patients with cirrhosis and ascites who have an increased activity of the renin–angiotensin system suggest that COX-2 inhibitors do not impair renal function in decompensated cirrhosis (57). The kidney produces vasoconstrictor substances, such as angiotensin II, endothelin, and adenosine. The production of these substances is stimulated in conditions of renal hypoperfusion. Therefore, these substances could also participate in the pathogenesis of HRS. If fact, it has been proposed that when severe renal hypoperfusion develops in cirrhosis with ascites, there could be a reduction of the intrarenal synthesis of vasodilators and a stimulation of the renal synthesis of vasoconstrictors secondary to renal ischemia, thereby creating vicious circles that lead to a rapidly progressive impairment of renal perfusion and GFR (type 1 HRS). This could explain why type 1 HRS usually occurs in patients with type 2 HRS, who already have a precarious equilibrium between vasoconstrictor and vasodilator mechanisms, and after a precipitating event (e.g., paracentesis, hemorrhage, and bacterial infection) that produces a further deterioration in circulatory function and renal perfusion. Once type 1 HRS develops, it progresses by the intrarenal mechanisms, independent of the correction of the precipitating event. Only the normalization of circulatory function can reverse these intrarenal vicious circles and improve renal perfusion and GFR in patients with type 1 HRS. Doppler studies of the brachial and femoral arteries, which supply blood mainly to the skin and muscles, and the middle cerebral artery, which supplies P.543 approximately 75% of the blood in the cerebral hemispheres, in patients with cirrhosis and ascites have also shown the presence of vasoconstriction in these vascular territories (42,43,44). Because cutaneous, muscular, and cerebral vascular resistance in patients with cirrhosis and ascites parallels renal vascular resistance and correlates closely with the degree of activity of the renin– angiotensin and the sympathetic nervous systems, it is clear that changes in these regional circulations in decompensated cirrhosis represent a homeostatic response to maintain the arterial pressure. An important point is that splanchnic arterial vasodilatation persists in decompensated cirrhosis despite the marked stimulation of the renin–angiotensin and the sympathetic nervous systems and the nonosmotic hypersecretion of antidiuretic hormone. This phenomenon is caused by marked resistance of the splanchnic arterioles to the vasoconstrictor effect of angiotensin II, noradrenaline, and vasopressin. Data on experimental cirrhosis suggest the resistance is caused by increased local synthesis of nitric oxide because inhibition of nitric oxide synthase normalizes the response of the splanchnic circulation to

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these vasoconstrictors. Therefore, splanchnic arterial vasodilatation in cirrhosis progresses with the increase in portal hypertension, induces the activation of the endogenous vasoconstrictor systems, and leads to vasoconstriction in the extrasplanchnic vascular territories. Because the splanchnic circulation in cirrhosis has little capacity to participate in the homeostasis of arterial pressure owing to the lack of response to vasoconstrictors, muscular and cutaneous blood flow is very low under rest conditions, and the cerebral circulation is regulated by effective mechanisms, the maintenance of circulatory function in cirrhosis relies mainly on the renal circulation. This explains why patients with cirrhosis and ascites are highly prone to the development of renal impairment and HRS in conditions associated with an impairment of circulatory function, such as bacterial infections, paracentesis, hemorrhage, and diuretic treatment.

Cardiac dysfunction in cirrhosis: A second important mechanism of circulatory and renal dysfunction and ascites Research on circulatory function in cirrhosis has focused for many years on the peripheral arterial circulation. Recent studies, however, suggest that in cirrhosis cardiac dysfunction is also present, which could be of major importance in the deterioration of circulatory and renal function and the pathogenesis of ascites and HRS (3,5). As indicated previously, arterial vasodilatation in the splanchnic circulation increases during the course of the disease, leading to homeostatic activation of the renin–angiotensin and sympathetic nervous systems to maintain arterial pressure. This progressive decrease in cardiac afterload should be followed by an increase in cardiac output and heart rate. However, this is not the case (Table 19.3). Heart rate in patients with nonazotemic cirrhosis, ascites, and normal or slightly increased activity of the renin–angiotensin and sympathetic nervous systems is similar to that in nonazotemic patients with increased activity of these systems or with HRS, indicating a severe impairment of cardiac chronotropic function. On the other hand, the cardiac output, although higher than normal in most cases, decreases progressively during the course of the disease. The mechanisms of circulatory dysfunction in cirrhosis may be, therefore, more complex than that proposed by the peripheral arterial vasodilatation hypothesis (Fig. 19.12). In patients with compensated cirrhosis, the splanchnic arterial vasodilatation is compensated by an appropriated cardiac response, with increased heart rate, left ventricular systolic ejection fraction, and cardiac output. However, with the progression of liver failure and portal hypertension this compensatory mechanism fails. The increase in arterial vasodilatation is not followed by an increase in heart rate. On the other hand, the cardiac output decreases rather than increases. Arterial pressure homeostasis is, therefore, solely dependent on the stimulation of the endogenous vasoconstrictor systems (i.e., renin–angiotensin system, sympathetic nervous system, and antidiuretic hormone), which has deleterious effects on renal perfusion and on the perfusion of other organs and produces sodium retention and leads to ascites formation.

Table 19.3. Chronologic Changes of Vasoactive Systems and Cardiovascular Function from Nonazotemic Cirrhosis with Ascites to Hepatorenal Syndrome

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NA-1

NA-2

HRS

88 ± 9

83 ± 9

75 ± 7

3 ± 2

10 ± 5

17 ± 14

221 ± 68

571 ± 241

965 ± 502

SVR (dyne s/cm 5 )

962 ± 256

1,058 ± 265

1,096 ± 327

CO (L/min)

7.2 ± 1.8

6.0 ± 1.2

5.4 ± 1.5

87 ± 15

85 ± 13

82 ± 14

MAP (mm Hg)

PRA (mg/mL h)

NE (pg/mL)

HR (beats/min)

Changes in plasma renin activity, norepinephrine concentration, and cardiac output were statistically significant (P < 0.01). NA, patients with nonazotemic cirrhosis and ascites; NA-1, patients with normal or slightly increased plasma renin activity and norepinephrine concentration; NA-2, patients with high plasma renin activity and norepinephrine concentration; HRS, hepatorenal syndrome; MAP, mean arterial pressure; PRA, plasma renin activity; NE, norepinephrine concentration; SVR, systemic vascular resistance; CO, cardiac output; HR, heart rate. From Ruiz del Arbol L, Urman J, Fernández J, et al. Systemic, renal and hepatic hemodynamic derangement in cirrhotic patients with spontaneous bacterial peritonitis. Hepatology 2003;38:1210–1218, with permission.

Cardiac chronotropic dysfunction in cirrhosis is probably related to the downregulation of β-adrenergic P.544 receptors owing to the overactivity of the sympathetic nervous system. The decrease in cardiac output is probably related to a reduction in cardiac preload (3). There is a cirrhotic cardiomyopathy characterized by an impaired left ventricular diastolic function and cardiac hypertrophy (58,59). It is, however, unlikely that it plays a significant role in the decrease in cardiac function because in decompensated cirrhosis cardiac output increases after maneuvers that expand the central blood volume (e.g., head-out water immersion, plasma volume expansion, therapeutic paracentesis, and insertion of a peritoneovenous or a TIPS), indicating a preserved cardiac reserve. Cardiac dysfunction in cirrhosis, therefore, appears to be a functional disorder unrelated to the structural changes in the heart.

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▪ Figure 19.12 The new hypothesis of circulatory dysfunction in cirrhosis. HRS, hepatorenal syndrome.

Pathogenesis of Ascites in Cirrhosis: The Forward Theory of Ascites The previous discussion shows that our concept on ascites formation is moving from the portal venous system to the splanchnic arterial vascular compartment. Ascites formation in cirrhosis was traditionally considered to be due to a rupture of the Starling equilibrium within the splanchnic microcirculation secondary to a backward transmission of the increased intrahepatic and portal pressure to the sinusoids and splanchnic capillaries, respectively, and to hypoalbuminemia. According to this traditional theory, renal dysfunction is the consequence of a reduction in circulating blood volume secondary to the leakage of intravascular fluid to the peritoneal cavity. The fact that plasma volume and cardiac output are not reduced, but rather increased, in most patients with cirrhosis and ascites, however, invalidates this hypothesis. The low peripheral vascular resistance in decompensated cirrhosis is also evidence against this theory because circulating hypovolemia is associated with arterial vasoconstriction rather than with arterial vasodilatation. The concept of effective hypovolemia was later proposed. Although circulating blood volume is increased in cirrhosis with ascites, the effective blood volume (the fraction of the blood volume present at a particular instant within the intrathoracic circulation that is able to influence low-pressure and high-pressure baroreceptors and, therefore, the sympathetic nervous activity, the renin– angiotensin system, and antidiuretic hormone) is actually reduced. This promotes sodium and water retention, which contributes to the formation of ascites. Results of subsequent studies confirmed this hypothesis. The transit time of blood within the intrathoracic vascular compartment is very short in patients with cirrhosis and ascites because of extremely rapid circulation as a consequence of the arterial vasodilatation. On the other hand, the intrathoracic blood volume is

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reduced in patients with cirrhosis and ascites compared with that in patients with compensated cirrhosis and in healthy persons (Fig. 19.13). Therefore, although the blood volume circulating per unit time (i.e., per minute) throughout the intrathoracic vascular compartment is increased in patients with ascites, the intrathoracic blood volume present at a particular moment P.545 is reduced owing to the hyperdynamic circulation. The splanchnic circulation, therefore, behaves as an arteriovenous fistula in decompensated cirrhosis (60). A large volume of blood enters into and leaves the portal venous system rapidly owing to the reduced splanchnic vascular resistance and the existence of portocollateral circulation. The hyperdynamic circulation leads to a vasodilatation in the pulmonary circulation to allocate the increased venous return, and this effect may be associated with an abnormal ventilation/perfusion ratio and low arterial oxygen saturation. Finally, increased venous return and arterial hypotension in the systemic circulation lead to increased stroke volume, tachycardia and, consequently, increased cardiac output. This closes the circle of the hyperdynamic circulation in decompensated cirrhosis.

▪ Figure 19.13 Central blood volume and mean transit time of central circulation in controls, in compensated cirrhosis, and in cirrhosis with ascites. (From Henriksen JH, Bendstsen F, Sorensen TI, et al. Reduced central blood volume in cirrhosis, Gastroenterology 1989;97:1506–1513, with permission.)

The recent demonstration that the hyperdynamic circulation diminishes during the course of the disease because of a decrease in the cardiac output adds a new

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dimension to the pathogenesis of circulatory dysfunction and ascites formation in cirrhosis (3). As the disease progresses, the hyperdynamic circulation, which is intense before and soon after the development of ascites, decreases, contributing to the stimulation of the endogenous vasoconstrictor systems. Angiotensin II, vasopressin, and the overactivity of the sympathetic nervous system produce significant vasoconstriction in the extrasplanchnic organs, including the kidneys, but not in the splanchnic circulation, which is resistant to these vasoconstrictor stimuli owing to an increase in the local synthesis of vasodilators. The circulatory profile of a patient with decompensated cirrhosis, therefore, consists of a progressive decrease of effective arterial blood volume because of both an increase in splanchnic arterial vasodilatation and a decrease in cardiac output; a progressive compensatory activation of the rennin–angiotensin system, sympathetic nervous system, and antidiuretic hormone; and a progressive impairment of the perfusion of extrasplanchnic organs. Because splanchnic arterial vasodilatation is the predominant mechanism by which splanchnic lymph formation is increased in cirrhosis, the pathogenesis of ascites can be satisfactorily explained on the basis of the changes in the arterial circulation induced by portal hypertension. This “forward” hypothesis considers that the accumulation of fluid within the peritoneal cavity is the consequence of the splanchnic arterial vasodilatation, which simultaneously produces a reduced effective arterial blood volume and a “forward” increase in splanchnic capillary pressure (Fig. 19.14). In patients with compensated cirrhosis or presinusoidal portal hypertension, the degree of portal hypertension and splanchnic arterial vasodilatation is moderate, the lymphatic system is able to return the excess of lymph produced in the hepatic and splanchnic area to the systemic circulation, and the arterial vascular underfilling is compensated by transient periods of sodium and water retention that increase the plasma volume and cardiac index and refill the dilated vascular bed. As cirrhosis progresses, however, portal hypertension and the secondary splanchnic arterial vasodilatation become progressively more intense and a critical point is P.546 reached at which the consequences of splanchnic arterial vasodilatation can no longer be compensated by increasing lymph return, plasma volume, and cardiac output. The patients have effective hypovolemia and sodium and water retention, but this fluid is ineffective in compensating this impairment of circulatory function because it escapes from the intravascular compartment because of an imbalance between the formation and the reabsorption of lymph. The final consequence of both disorders is the continuous formation of ascites.

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▪ Figure 19.14 The “forward” theory of ascites formation.

During the initial stages of decompensated cirrhosis, sodium retention occurs despite normal levels of renin, aldosterone, and norepinephrine. It has been proposed that sodium retention at this period may be caused by mechanisms unrelated to a reduction in effective blood volume (reduced hepatic metabolism of some endogenous substance with sodium-retaining effect or a direct hepatorenal reflex) and may promote sodium retention. This is highly unlikely because these patients have hemodynamic characteristics identical to those of patients with ascites and high renin levels. The most likely explanation is that a still unknown mechanism extremely sensitive to changes in effective blood volume induces sodium retention at these early stages of decompensated cirrhosis. This mechanism would be more sensitive than that of the sympathetic nervous system and renin–angiotensin–aldosterone system and, consequently, would be stimulated earlier. Activation of the sympathetic nervous system and the renin– angiotensin–aldosterone system represents a further step and indicates more severe impairment of circulatory function as a consequence of the progression of the disease. Finally, the level of plasma antidiuretic hormone, the secretion of which is highly sensitive to small changes in serum osmolality but requires greater changes in effective blood volume, increases at later stages of the disease. This phenomenon explains why dilutional hyponatremia is a late event in the course of decompensated cirrhosis.

Management of Ascites in Cirrhosis Bed rest, low sodium diet, and diuretics The assumption of an upright posture associated with moderate physical exercise by patients with cirrhosis and ascites induces a marked stimulation of the renin–

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angiotensin–aldosterone system and sympathetic nervous system (61). Therefore, from a theoretic point of view, bed rest may be useful in patients with poor response to diuretics. Because the natriuretic action of loop diuretics starts soon after administration and disappears approximately 3 hours later, bed rest should be adjusted to this time schedule. The effect of spironolactone lasts for more than 1 day and, therefore, is not important in planning bed rest. Mobilization of ascites occurs when a negative sodium balance is achieved. In 10% to 20% of patients, those spontaneously excreting relatively high amounts of sodium in the urine, this can be obtained simply by reducing the sodium intake to 40 to 70 mEq/day (i.e., no salted food, no salt during cooking, no salt on the table). A greater reduction in sodium intake interferes with the nutrition of the patients and is not advisable (62). In most instances, a negative sodium balance cannot be achieved unless urinary sodium excretion is increased with diuretics. Even in these patients, sodium restriction is important because it reduces diuretic requirements. Patients responding satisfactorily to diuretics may be allowed to increase the sodium intake up to 70 to 100 mEq/day if they do not tolerate the standard low sodium diet. However, sodium restriction is essential in the care of patients responding poorly to diuretics. A frequent cause of “apparently” refractory ascites is inadequate sodium restriction. This should be suspected whenever ascites does not decrease despite a good natriuretic response to diuretics. Once ascites is mobilized, it is better to reduce the diuretic dosage than to increase sodium intake. Furosemide and spironolactone are the diuretics most commonly used in the treatment of ascites in patients with cirrhosis. Furosemide, as do other loop diuretics (torsemide, ethacrynic acid, bumetanide), inhibits chloride and sodium reabsorption in the thick ascending limb of the loop of Henle but has no effect on the distal nephron (distal and collecting tubules). Furosemide is rapidly absorbed from the intestine, is highly bound to plasma proteins, and is actively secreted from the blood into the urine through the organic acid transport pathway in the proximal tubule. Once in the luminal compartment, furosemide is carried in the luminal fluid to the loop of Henle, where it inhibits the Na + -2Cl - -K + cotransport system located in the luminal membrane of the ascending limb cells, and sodium reabsorption occurs in this segment of the nephron. Because between 30% and 50% of the filtered sodium is reabsorbed in the loop of Henle, it is not surprising that furosemide has a high natriuretic potency. At high dosage, it can increase sodium excretion by up to 30% of the filtered sodium in healthy subjects. Furosemide also increases the synthesis of prostaglandin E 2 by the ascending limb cells. This effect is related to the natriuretic effect because nonsteroidal anti-inflammatory drugs reduce its natriuretic activity. The onset of action of furosemide is extremely rapid (within 30 minutes of oral administration), with the peak effect occurring within 1 to 2 hours and most natriuretic activity stopping 3 to 4 hours after administration. Spironolactone undergoes extensive metabolism that produces numerous biologically active compounds, the P.547 most important one being canrenone. These aldosterone metabolites are tightly bound to plasma proteins from which they are released slowly to the kidney and other organs. Spironolactone metabolites act by competitively inhibiting the tubular effect of aldosterone on the distal nephron. This hormone enters the collecting tubule through the basolateral membrane and interacts with a cytosolic receptor. The aldosterone receptor complex is translocated to the nuclei and

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interacts with specific DNA sequences, stimulating the release of messenger ribonucleic acid and the synthesis of sodium channels, which are inserted into the luminal membrane, and the transporter Na + /K + -adenosine triphosphatase (ATPase), which activates the extrusion of sodium from the intracellular space into the peritubular interstitial space. The effect of this transporter together with the activation of potassium channels in the luminal membrane is the predominant mechanism of the kaliuretic effect of aldosterone. Spironolactone metabolites also enter the basolateral membrane in the collecting tubule and interact with the cytosolic receptor, but the complex spironolactone metabolite receptor is unable to interact with DNA. Therefore, spironolactone acts as a specific antagonist of aldosterone. The half-life of the aldosterone-induced proteins and of spironolactone metabolites is relatively prolonged, explaining the lag of 2 to 3 days between the initiation or the discontinuation of spironolactone treatment and the onset or the end of the natriuretic effect, respectively. Spironolactone metabolism is impaired in cirrhosis, such that the terminal half-life of spironolactone metabolites is increased in this condition. Because the amount of sodium reabsorbed in the collecting tubule is low, spironolactone and other distal diuretics (e.g., triamterene, amiloride) have a much lower natriuretic potency than furosemide. They are able to increase sodium excretion by up to 2% of the filtered sodium. The administration of furosemide at relatively high doses (80 to 160 mg/day) to nonazotemic patients with cirrhosis and ascites gives rise to a satisfactory natriuretic response in only 50% of cases. In contrast, most of these patients respond to spironolactone at doses of 150 to 300 mg/day (55) (Table 19.4). The mechanism of this resistance to the natriuretic effect of furosemide is mainly pharmacodynamic. Most of the sodium not reabsorbed in the loop of Henle by the action of furosemide is subsequently reabsorbed in the distal nephron by the action of aldosterone. Patients responding to furosemide are those with normal or only moderately increased plasma aldosterone levels. Patients with marked hyperaldosteronism usually do not respond to this drug. The response to spironolactone depends on the degree of hyperaldosteronism. Patients with a normal or slightly increased plasma concentration of aldosterone usually respond to low doses of spironolactone (100 to 150 mg/day), but as much as 300 to 400 mg/day may be needed to antagonize the tubular effect of aldosterone in patients with marked hyperaldosteronism. The basic drug for the treatment of ascites, therefore, is spironolactone. Simultaneous administration of furosemide and spironolactone increases the natriuretic effect of both agents and reduces the incidence of hypo- or hyperkalemia that can occur when these drugs are given alone.

Table 19.4. Comparison of the Efficacy of Furosemide and Spironolactone in Nonazotemic Cirrhosis with Ascites

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Positive

Negative

response

response

Total

Furosemide

11

10 a

21

Spironolactone

18

1b

19

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χ 2 =6.97; P < 0.01. a b

Nine cases responded later to spironolactone. This case did not respond later to furosemide.

From (63) Pérez-Ayuso RM, Arroyo V, Planas R, et al. Randomized comparative study of efficacy of furosemide versus spironolactone in nonazotemic cirrhosis with ascites. Gastroenterology 1984;84:961–968, with permission.

Two different diuretic approaches can be used in patients with cirrhosis and ascites. The step-care approach (64) consists of the progressive implementation of the therapeutic measures currently available, starting with sodium restriction. If ascitic volume does not decrease (as measured by loss of body weight), spironolactone is given at increasing doses (starting with 100 mg/day; if no response is seen within 4 days, increasing to 200 mg/day; and if no response is seen, further increasing to 400 mg/day). When there is no response to the highest dose of spironolactone, furosemide is added, also by increasing the dosage every 2 days (40 to 160 mg/day). The second approach is the combined treatment. It begins with the simultaneous administration of sodium restriction, spironolactone 100 mg/day, and furosemide 40 mg/day. If the diuretic response is insufficient after 4 days, the dose is increased to 200 mg/day and 80 mg/day, respectively. For patients who do not respond despite the increase in dosage, spironolactone and furosemide are increased to 400 mg/day and 160 mg/day, respectively. A recent randomized controlled trial has shown that the step-care and the combined treatment approaches are similar in terms of response rate, rapidity of ascites mobilization, and incidence of complications (65). There is a general agreement that patients not responding to 160 mg/day of furosemide and 400 mg/day of spironolactone will not respond to higher doses of these diuretics. For patients receiving the combined treatment with an exaggerated response, P.548 diuretic administration should be adjusted with a reduction in the dose of furosemide. The goal of diuretic treatment should be to achieve a weight loss of 300 to 500 g/day in patients without peripheral edema and 500 to 1,000 g/day in patients with peripheral edema. Once ascites is mobilized, diuretic treatment should be reduced to keep the patients free of ascites. The most important predictor of diuretic response in patients with cirrhosis and ascites is the degree of impairment of circulatory and renal function. Patients with increased serum creatinine levels (>1.2 mg/dL; upper normal limit), dilutional hyponatremia (serum sodium concentration 2 mg/dL, decrease in serum sodium level by >10 mEq/L to a concentration 1.5 mg/dL) or lesser despite marked degrees of impairment of renal perfusion and GFR (serum creatinine level between 1.2 and 1.5 mg/dL). It has P.552

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been estimated that a serum creatinine level greater than 1.2 mg/dL in patients with cirrhosis and ascites reflects a decrease of renal blood flow and GFR greater than 50% with respect to values in healthy persons. The most important mechanisms of refractory ascites are (a) impairment of the access of diuretics to the effective sites on the tubular cells due to the renal hypoperfusion and (b) reduced delivery of sodium to the ascending limb of the loop of Henle and the distal nephron secondary to the low GFR and an excessive sodium reabsorption in the proximal tubule. Inadequate sodium restriction or the use of nonsteroidal anti-inflammatory drugs should be ruled out in the evaluation of any patient with the presumptive diagnosis of diuretic-resistant ascites. Three different treatments can be used for the management of patients with cirrhosis and refractory ascites: Peritoneovenous shunting, TIPS, and therapeutic paracentesis (71,72). Peritoneovenous shunting was the first treatment specifically designed for patients with refractory ascites. LeVeen et al. introduced the first prosthesis in 1974. It consists of a perforated intra-abdominal tube connected through a one-way pressure-sensitive valve to a second tube that traverses the subcutaneous tissue up to the neck, where it enters the internal jugular vein. The tip of the intravenous tube is located in the superior vena cava near the right atrium. Insertion of a LeVeen shunt is technically simple and can be performed under local anesthesia. It is advisable to remove most of the ascitic fluid before the insertion of the prosthesis to avoid early complications related to the massive passage of ascites to the general circulation (e.g., pulmonary edema, variceal hemorrhage, and severe intravascular coagulation). Prophylactic administration of antistaphylococcal antibiotics before and after surgery is also recommended. Although the LeVeen shunt is the most widely used, other types, such as the Denver shunt, are available. However, they do not improve the results obtained with the initial prosthesis. The shunt produces a sustained expansion of the circulating blood volume by the continuous passage of ascitic fluid from the abdominal cavity to the systemic circulation; a marked suppression of the plasma levels of renin, norepinephrine, and antidiuretic hormone; and an increased response to diuretics. Therefore, it is a rational therapy for refractory ascites (10). Unfortunately, obstruction of the shunt is common and occurs in approximately 40% of patients within the first postoperative year; it is usually due to the deposition of fibrin either in the valve or around the intravenous catheter, thrombotic obstruction of the venous limb of the prosthesis, or thrombosis of the superior vena cava. Although thrombosis of the vena cava is usually incomplete, total occlusion can occur, resulting in the development of a superior vena cava syndrome. Shunt occlusion requires reoperation, removal of the obstructed shunt, and insertion of a new prosthesis. Another long-term complication of peritoneovenous shunting is small-bowel obstruction, which occurs in approximately 10% of patients. Small intestinal obstruction is caused by marked intraperitoneal fibrosis and can make further intra-abdominal procedures, such as liver transplantation, impossible. The reintroduction of therapeutic paracentesis has markedly reduced the use of peritoneovenous shunting in patients with refractory ascites. Results of two randomized controlled trials have been published in which paracentesis was compared with use of a LeVeen shunt in the care of these patients. Although shunting was clearly superior in the long-term control of ascites, it had no effect on the course of the disease. Patients from both therapeutic groups did not differ in the time to first readmission to the hospital during the follow-up and survival (Table 19.5). Furthermore, frequent reoperations were needed because of shunt

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obstruction (10). These data led the International Ascites Club to propose that paracentesis is preferred to peritoneovenous shunting for the management of refractory ascites. TIPS is the most recent treatment introduced for the management of refractory ascites. It works as a side-to-side portacaval shunt and, from a theoretic point of view, it should correct the two principal mechanisms in the pathogenesis of ascites (71). By doing so, it should suppress the endogenous vasoconstrictor system, improve renal perfusion and GFR, and increase the response to diuretics. On the other hand, by decompressing both the splanchnic and the hepatic microcirculation, TIPS should decrease the formation of lymph both in the liver and in the other splanchnic organs. A review of the records of the first 358 reported patients with refractory ascites treated with TIPS clearly indicated that this therapeutic procedure is extremely effective in improving circulatory and renal function and in managing ascites in these patients (71). TIPS induces a marked increase in cardiac output, a decrease in systemic vascular resistance, and an elevation in right atrial pressure, pulmonary artery pressure, and pulmonary wedge pressure (59,60). These changes, which P.553 are similar to those after peritoneovenous shunting, are probably caused by an increase in venous return resulting from the presence of portacaval fistula. The decrease in systemic vascular resistance, which is also a constant feature in patients treated by peritoneovenous shunting, is probably a physiologic response to accommodate the increase in cardiac output.

Table 19.5. Peritoneovenous Leveen Shunt Versus Therapeutic Paracentesis in the Management of Refractory Ascites: Efficacy, Associated Complications, and Survival

Paracentesis (n = 38)

LVS (n = 42)

Ascites episodes

125

38

LVS obstruction a

—

40%

48 ± 8

44 ± 6

57%

44%

Time in hospital (days)

Survival a

1-year probability. LVS, LeVeen shunt.

a

Because it increases the hyperdynamic circulation, it has been suggested that TIPS impairs the systemic hemodynamics in cirrhosis. However, results of studies of the effects of TIPS on the endogenous vasoactive systems do not support this concept. The results indicate that effective arterial blood volume is markedly improved after TIPS insertion in patients with cirrhosis and ascites. As indicated

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earlier, the maintenance of arterial pressure in patients with advanced cirrhosis and ascites is critically dependent on a marked overactivity of the renin– angiotensin system, sympathetic nervous system, and antidiuretic hormone. If TIPS enhances arterial vasodilatation, a further increase in the degree of stimulation of these vasoconstrictor systems should occur. In contrast, TIPS insertion is associated with marked suppression of the plasma levels of renin, aldosterone, norepinephrine, and antidiuretic hormone (59,60). Suppression of the renin–angiotensin–aldosterone system occurs within the first week of TIPS insertion and persists during the follow-up period. Suppression of norepinephrine and antidiuretic hormone seems to require a longer period of time. Deterioration in circulatory function should also be associated with a further impairment of renal function after TIPS insertion; however, this process induces a rapid increase in urinary sodium excretion, which is already observed within the first 1 to 2 weeks and persists during the follow-up period (59,60). A significant increase in serum sodium concentration and GFR is also observed, indicating an improvement in renal perfusion and free water clearance. However, these latter changes require 1 to 3 months to occur. TIPS induces a marked decrease in the portacaval gradient. In the aforementioned review of the care of 358 patients with refractory ascites treated by TIPS, the mean decrease was from 20.9 to 10 mm Hg (60). Portal venous pressure also decreased markedly, from 29.4 to 21.8 mm Hg. However, TIPS only partially decompresses the portal venous system; portal venous pressure in most healthy subjects is less than 5 mm Hg. Although suppression of the renin– aldosterone system is evident, the plasma levels of renin and aldosterone do not decrease to normal levels. Improvement in splanchnic and systemic hemodynamics is associated with the disappearance of ascites or partial response (no need for paracentesis) in most patients. Only 10% of cases do not respond to TIPS. Ascites characteristically resolves slowly (within 1 to 3 months). Continuous diuretic treatment is required in more than 95% of cases, either for the management of ascites or to reduce the peripheral edema that frequently occurs in patients treated with TIPS. The persistence of portal hypertension and hyperaldosteronism may be the explanation for this phenomenon. Hepatic encephalopathy is the most important complication among patients with cirrhosis and refractory ascites managed with TIPS (60). More than 40% of patients have this complication. In most cases hepatic encephalopathy responds to standard therapy. However, it occasionally requires a decrease in stent size. Although hepatic encephalopathy before insertion of TIPS is a predictor of encephalopathy after its insertion, new or worsening hepatic encephalopathy develops in approximately 30% of cases. Shunt dysfunction is also a major problem, occurring in approximately 40% of cases within the first year. This is an important limitation of TIPS that necessitates frequent retreatments. The 1-year probability of survival among patients with cirrhosis and refractory ascites treated with TIPS is extremely poor. Early mortality (within 30 days of insertion of TIPS) is approximately 12% and late mortality is 40%. Predictors of survival are the Child-Pugh score, age, and the presence of HRS before TIPS insertion (60). Five randomized controlled trials have been reported comparing TIPS and therapeutic paracentesis (73,74,75,76,77). Two included patients with recidivant and refractory ascites, and three included patients with only refractory ascites. The five trials clearly showed that TIPS was better than paracentesis in the longterm control of ascites. Three trials showed significantly higher incidence of

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hepatic encephalopathy in patients treated with TIPS. An improvement in survival in the TIPS group was observed only in the trials including patients with recidivant ascites. The total time in hospital during follow-up was similar in both groups owing to the high incidence of shunt obstruction requiring new hospitalization for treatment of complications related to portal hypertension and/or restenting (Table 19.6). In one of these trials the quality of life was assessed and changes were similar in the two therapeutic groups (78). These results indicate that TIPS changes the course of cirrhosis from ascites to hepatic encephalopathy without improving the overall results of paracentesis in relation to length of hospitalization and survival.

Treatment of Patients with Cirrhosis, Ascites, and Hyponatremia or Hepatorenal Syndrome Hyponatremia in patients with cirrhosis and ascites is usually asymptomatic, even in those with markedly reduced serum sodium concentration. On the other hand, it does not contraindicate diuretic treatment P.554 because most patients respond to treatment without a further reduction in serum sodium concentration. Therefore, the use of aggressive procedures (e.g., peritoneovenous shunting, TIPS) for the treatment of hyponatremia is not justified. The intravenous administration of sodium chloride may produce a transient increase in serum sodium concentration but at the expense of increasing the rate of ascites formation. Finally, water restriction is difficult to carry out and is rarely effective. Therefore, at present there is no treatment for dilutional hyponatremia in cirrhosis. However, the future is very promising. Several specific antagonists of the renal effect of antidiuretic hormone (V2 antagonists) have been developed by different pharmaceutical companies and tested for treatment of patients with cirrhosis, ascites, and dilutional hyponatremia (11,12,79,80). These agents produce a marked increase in urine volume without a concomitant increase in urine sodium and solute excretion; this effect is associated with a significant increase in serum sodium concentration and serum osmolality in most patients. There are, however, patients in whom hyponatremia is refractory to aquaretic drugs (11), indicating that mechanisms other than antidiuretic drugs play an important role in the pathogenesis of free water retention in cirrhosis. The aquaretic drugs, therefore, will be important for the management of patients with cirrhosis. Potential indications would be not only the treatment of spontaneous dilutional hyponatremia but also the prevention and treatment of diuretic-induced hyponatremia.

Table 19.6. Transjugular Intrahepatic Portacaval Shunt Versus Paracentesis for Refractory Ascites—Summary of Studies

Lebrec et al. (73)

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Type of

Control of

Hepatic

ascites

ascites

encephalopathy

Better with

No difference

Refractory

TIPS

Survival Worse with TIPS

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Rössle

Refractory

Better

et al. (74)

and recidivant

with TIPS

Ginès et

Refractory

Better

al. (76)

No difference

Better with TIPS

Worse with TIPS

No

with

difference

TIPS

Sanyal

Refractory

et al. (77)

Better

Worse with TIPS

No

with TIPS

Salerno

Refractory

Better

et al. (75)

and recidivant

with TIPS

difference

Worse with TIPS

Better with TIPS

TIPS, transjugular intrahepatic portacaval shunt.

Table 19.7. Effects of 1- to 2-Week Treatment with Ornipressin or Terlipressin Plus Albumin on Mean Arterial Pressure, Plasma Renin Activity, Norepinephrine, and Serum Creatinine Levels in Type 1 Hepatorenal Syndrome

Baseline (n =

Day 7 (n =

Day 14 (n =

15)

9)

7)

MAP (mm Hg)

70 ± 8

77 ± 9

79 ± 12

PRA (ng/mL h)

15 ± 15

2 ± 3

1 ± 1

1,257 ± 938

550 ± 410

316 ± 161

3 ± 1

2 ± 1

1 ± 1

NE (pg/mL)

Creatinine (mg/dL)

Normal values: Plasma renin activity Table of Co ntents > Volume I > Section III - Consequences o f Liver Disease > Chapter 20 - Hepatic Encephalo pathy

Chapter 20 Hepatic Encephalopathy Juan Córdoba Andrés T. Blei

Key Concepts z

Hepatic encephalopathy is a neuropsychiatric syndrome that encompasses multiple manifestations resulting from liver failure and/or portosystemic shunting.

z

The neurologic abnormalities are potentially reversible with correction of the liver disease and/or the abnormal portal collateral circulation.

z

The pathogenesis of hepatic encephalopathy is multifactorial and relates to the exposure of the brain to toxins that arise mostly from the gut.

z

Several neurotoxic substances have been implicated in the development of hepatic encephalopathy; ammonia is an important factor in its pathogenesis.

z

The most characteristic manifestation is confusional syndrome in patients with cirrhosis, precipitated by a factor that enhances the toxin's effect or load.

z

Treatment is based on the identification and correction of the precipitating factor, provision of supportive measures, and the administration of drugs that decrease the production of toxins or antagonize their effects on the brain.

z

Management of patients with hepatic encephalopathy, in addition to the assessment of neurologic manifestations, should include the treatment of the underlying liver disease and/or the abnormal portal collateral circulation.

Hepatic encephalopathy (HE) can be defined as a disturbance in central nervous system (CNS) function due to hepatic insufficiency or portosystemic shunting. This vague definition reflects the existence of a spectrum of neurologic manifestations that develop in association with different liver diseases (1). A common link is the potential reversibility of the neurologic manifestations once the abnormality of liver function is corrected, as well as the importance of shunting of blood arising from the portal venous bed into the systemic circulation. HE must be differentiated from the concurrence of neurologic symptoms and liver disease secondary to a common pathogenetic mechanism such as brain and liver damage caused by alcohol or copper (Wilson disease). HE must also be differentiated from neurologic disturbances directly caused by bilirubin accumulation, hypoglycemia, disorders of blood coagulation, or other well-defined abnormalities that are secondary to liver failure. The nomenclature of HE is confusing. Some terms are used with different meanings by different authors. Some efforts have been made to reach a consensus, especially for the design of clinical trials (2). Despite this limitation, from a clinical perspective HE is generally classified according to the underlying liver disease and the evolution of the neurologic manifestations (Table 20.1). The most frequent liver disease is cirrhosis, usually accompanied by extrahepatic portosystemic shunts (spontaneous or surgical). HE can also be seen in acute liver failure, in which it constitutes a clinical hallmark of the disorder. In rare cases, HE develops in the absence of any sign of parenchymal liver disease and is P.570 caused solely by portosystemic shunting of congenital or surgically induced origin.

Table 20.1. Classification of Hepatic Encephalopathy

Extrahepatic Hepatic encephalopathy

Liver disease

portosystemic

Neurologic

shunting

manifestations

Specific features

Acute episode

In cirrhosis

Cirrhosis

Variable

Acute confusional

Usually precipitated

state to coma

In acute liver failure

Acute liver

Absent

failure

Acute confusional

Frequently complicated by

state to coma

brain edema and intracranial hypertension

Chronic

Relapsing

Persistent

Cirrhosis

Cirrhosis

Severe

Severe

Relapsing episodes

Usually without

of encephalopathy

precipitating factors

Persistent cognitive

Generally related to

or motor

surgically induced shunts

abnormalities

Minimal hepatic

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Cirrhosis

Variable

Asymptomatic

Abnormalities revealed by

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encephalopathy

neuropsychological or neurophysiologic tests

In patients with portosystemic bypass

No signs of parenchymal

with no intrinsic liver

disease

Large shunts

Relapsing episodes and persistent

Rare disorder, secondary to congenital abnormalities or

abnormalities

surgical shunts

disease

Along the lines of Ferenci P, Lockwood A, Mullen K, et al. Hepatic encephalopathy–definition, nomenclature, diagnosis, and quantification: final report of the working party at the 11th World Congresses of Gastroenterology, Vienna, 1998. Hepatology 2002;35:716–721.

The neurologic manifestations of HE are variable. The most distinctive presentation is an acute episode characterized by the sudden onset of an acute confusional state that can evolve into coma. Neuromuscular abnormalities are common, the most characteristic being the presence of asterixis; pyramidal signs may also be present. The term chronic HE is reserved for patients who have frequent episodes of encephalopathy or persistent cognitive (e.g., memory loss, confusion, and disorientation) or neuromuscular (e.g., tremor, apraxia, and rarely paraplegia) disturbances. Minimal HE (previously termed subclinical HE) corresponds to those neurologic manifestations not obvious at clinical examination but detected with neuropsychological or neurophysiologic tests (3).

Pathogenesis General Aspects Different hypotheses have been proposed to explain the changes in mental state that occur in HE. Ideally, such a theory should explain the relation between liver abnormalities, neurologic disturbances, and clinical manifestations. However, establishing such relations is difficult, in part because of limitations in the methods available to study brain function in humans in vivo and limitations in knowledge of the neurobiologic basis of behavior. For these reasons, any hypothesis on the pathogenesis of HE should be able to explain the improvement with a specific treatment or account for the mechanism of action of a precipitating factor. A common pathogenetic notion is that HE is caused by substances that under normal circumstances are efficiently metabolized by the liver, rather than by an insufficient production of substrates that could be essential for neurologic function (Fig. 20.1). In light of this notion, portosystemic shunting plays a critical role because the main impact of this circulatory disturbance is on the concentration of gut-derived substances that are highly cleared by the liver. Studies of crossperfusion in animals with experimental HE and of liver support systems in humans have shown that clearance of toxic substances present in the blood is more important to improve mental function than the synthetic capacity of the support system. In patients with liver disease, these toxic substances reach the systemic circulation through portosystemic shunting or reduced hepatic clearance and produce deleterious effects on brain function. Once the toxic substances are in neural tissues, a large number of neurochemical changes occur that affect multiple neurochemical pathways, each affected to a variable extent. Historical hypotheses have ranged from single unifying theories (4) to the notion of HE as a multifactorial process (5). As in other metabolic encephalopathies, general neuronal dysfunction results P.571 in abnormalities of consciousness. However, in contrast to other conditions that affect consciousness (such as hypoglycemia), in which neuronal function is primarily affected, a unique feature of HE is the abnormality of astrocyte morphology and function (See “Abnormalities in the Central Nervous System”). This feature has led to a view that in HE the abnormality in consciousness is the consequence of altered astrocyte–neuronal communications, resulting in changes of multiple neurotransmitter systems (6). Alternative views, such as the γ-aminobutyric acid (GABA) theory, explain the spectrum of HE through the direct effect of a toxin on a key aspect of neurologic function (7). Other paradigms arise from the experimental observation that different toxins (e.g., fatty acids or mercaptans) enhance the negative effects of ammonia on consciousness (synergistic theory) (8). More recently, the concept of synergism has been expanded to include the contribution of systemic inflammation to the encephalopathic process (9). Finally, current views also emphasize differing effects of different toxins at various neurologic levels. For example, manganese appears to be involved in parkinsonian manifestations but not in decreasing arousal. In addition, the relative importance of each toxin (See “Putative Toxins”) and the site where they cause their main effect (See “Abnormalities in the Central Nervous System”) is modulated by different factors (See “Factors that Favor the Effects of Toxins”).

▪ Figure 20.1 A traditional paradigm of the pathogenesis of encephalopathy emphasizing the interplay between liver failure and portosystemic shunting for the availability of toxins in the systemic circulation. A current paradigm includes a multiorgan abnormality in the “periphery.” Several factors potentiate the effects of ammonia on the brain, where the presence of multiple neurotransmitter abnormalities can be explained by altered intercellular communications between astrocytes (A), neurons (N),

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and endothelial cells (EC).

Putative Toxins Ammonia Ammonia has historically been viewed as the most important factor in the genesis of HE. The importance of ammonia in the pathogenesis of HE is highlighted by the following five sets of observations: (a) Ammonia is produced by the gut and a significant amount is of bacterial origin (10), (b) the concentration of ammonia in portal blood is high and a high degree of extraction occurs in the liver (11), (c) concentrations of ammonia are high in the systemic circulation and the cerebrospinal fluid (CSF) of patients with HE (12), (d) precipitating factors cause elevations in the blood level of ammonia or result in the exposure of brain tissue to ammonia (13), (e) treatment strategies of clinical benefit decrease the blood level of ammonia (14). Ammonia is generated in different tissues by the breakdown of amino acids and other nitrogenous substances (10). Under normal physiologic conditions, ammonia enters the portal circulation from the gastrointestinal tract, where it is derived from colonic bacteria and from the deamidation of glutamine in the small bowel. Traditionally, absorption was viewed as the result of passive diffusion; more recent studies indicate the presence of specific ammonia transporters (15). Regardless of the mechanism of absorption, ammonia reaches high concentration in the portal blood and P.572 undergoes a high first-pass hepatic extraction (80%). In the liver, ammonia is transformed in the periportal hepatocytes into urea (a high-capacity and low-affinity system) and in the centrovenular hepatocytes into glutamine (a low-capacity and high-affinity system). Urea is quantitatively the most important product of ammonia metabolism and elimination. Circulating urea diffuses into the intestine (40%), where it undergoes hydrolysis into ammonia through ureases present in the colonic bacteria. Urinary elimination of nitrogen in the form of urea is a route of ammonia disposal from the organism. In addition to the intestine and the liver, kidney and muscle contribute to regulate the arterial ammonia level (16). In muscle, ammonia is transformed into glutamine through the action of glutamine synthetase. Experiments in normal volunteers showed that 50% of injected

1 5 N-ammonia

is removed by the muscles (17). The ability of the muscle to “fix” appreciable amounts of blood-borne

ammonia becomes important for regulating arterial ammonia in case of liver failure and highlights the importance of maintaining an adequate muscular mass by patients with HE. It is generally accepted that at rest skeletal muscle is an ammonia-consuming organ. However, during moderate to heavy exercise, the muscle releases ammonia (18). The kidneys generate ammonia from the deamination of glutamine, a step involved in the regulation of arterial and urinary pH. A small fraction of renal ammonia is released into the systemic circulation; urinary ammonia excretion may be affected by dehydration and increases in conditions of hyperammonemia (19). Notwithstanding the role of peripheral organs, the main factors resulting in the increase in blood levels of ammonia in liver failure are a decrease in the capability of the liver to generate urea and glutamine and the bypass of first-pass hepatic metabolism through portosystemic shunts.

▪ Figure 20.2 Relationship between venous levels of ammonia and clinical stage of hepatic encephalopathy (HE)—NH 3 (left graph, r = 0.69, P < 0.001) or pNH 3 (right graph, r = 0.79, P < 0.001). (From Kramer L, Tribl B, Gendo A, et al. Partial pressure of ammonia versus ammonia in hepatic encephalopathy. Hepatology 2000;31:30–34.)

Patients with HE have an increased diffusion of ammonia into the brain (12), although recent studies using sophisticated positron emission tomography techniques have questioned this tenet (20). Variations in the passage of ammonia across the blood–brain barrier may explain the poor relationship between the level of arterial ammonia and the degree of HE, which nonetheless can be seen when large groups of patients are compared (Fig. 20.2; (21)). Glutamine in brain tissue, which is the product of ammonia metabolism and can be estimated by

1

H-magnetic resonance spectroscopy, and glutamine level in CSF is more related to HE than

the blood level of ammonia (22). Ammonia has many deleterious effects on brain function and affects multiple neurotransmitter systems (Table 20.2). However, the clinical manifestations of pure ammonia intoxication differ from the usual manifestations of HE. Patients with urea cycle disorders have symptoms at much higher levels of blood ammonia than those with liver failure. They may also exhibit mental retardation, seizures, and agitation, which are not common in HE. Brain edema leading to intracranial hypertension, a common feature of acute ammonia intoxication, is not clinically relevant in patients with cirrhosis and HE. Additional studies are required to determine whether the differences between these two situations relate to the presence of additional toxins, rate of exposure of the brain, activation of compensatory mechanisms, or other time-dependent factors.

γ-Aminobutyric acid agonists Several lines of evidence support the presence of activated GABAergic tone in HE (23). One of the postulated mechanisms for this effect is the increased availability of agonist ligands of the GABA receptor complex, a P.573 key inhibitory neurotransmitter in the brain. The term natural benzodiazepines has been coined for a group of substances of nonpharmacologic origin that bind to the benzodiazepine site of the GABA receptor, where they can act as an agonist or antagonist. These substances, which are poorly characterized from a chemical and functional perspective, have been reported to be present in a variety of human tissues in normal conditions and to purportedly accumulate in the brain of patients with HE (24). It has been

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proposed that natural benzodiazepines with agonistic effects on the GABA receptor induce a decrease of consciousness in HE. However, not all the benzodiazepine ligands found in HE have agonistic effects on the GABA receptor (e.g., diazepam-binding inhibitor). Furthermore, alternative routes of activation of GABA neurotransmission may be present. These include direct and indirect effects of ammonia on the affinity of GABA receptors to its natural ligand (7). Ammonia may also lead to an increased density of peripheral-type benzodiazepine receptors (PTBRs) present in astrocytic mitochondria and whose activation results in the synthesis of neurosteroids, powerful ligands of neuronal GABA receptors (25,26).

Table 20.2. Effects of Ammonia on Nervous Tissue

Effects

Possible consequences

Blocking of chloride channels

Impairment of postsynaptic inhibition

Increase in the transport of neutral amino acids and cerebral

Interaction with serotonin-related

tryptophan

neurotransmission

Decrease in the activity of α-ketoglutarate dehydrogenase

Decrease in cerebral energy metabolism

Enhancement of the synthesis of neurosteroids

Agonistic effects on GABA neurotransmission

Modulation of GABA receptor


Upregulation of peripheral benzodiazepine receptors


Downregulation of glutamatergic synaptic uptake

Interaction with glutamate-related neurotransmission

Increase in brain glutamine

Interaction with glutamatergic neurotransmission Brain edema

Increase in nitric oxide synthesis

Interaction with glutamatergic neurotransmission

GABA, γ-aminobutyric acid. Butterworth RF. The neurobiology of hepatic encephalopathy. Semin Liver Dis 1996;16:235–244.

Several arguments have been proposed in favor of a role for natural benzodiazepines in HE. The most relevant is the observation of an improvement of mental state after the administration of flumazenil (a benzodiazepine receptor antagonist) in some patients with advanced stages of HE who have not consumed benzodiazepines of pharmacologic source (27). However, the beneficial effects of flumazenil, usually mild and transient, are only seen in a subgroup of patients. One of the main limitations of this theory is the lack of an explanation of the mechanism by which the concentration of natural benzodiazepines increases in HE. A study in rats with experimental HE showed the generation of precursors of natural benzodiazepines in the intestinal flora (28). These precursors are transformed into natural benzodiazepines in the brain and accumulate secondary to liver failure. However, additional studies in humans to confirm the link between intestinal flora, liver function, natural benzodiazepines, and HE are lacking. An alternative source of natural benzodiazepines could be hemoglobin; metabolites of hemoglobin that mimic benzodiazepines have been described (29).

Manganese Manganese is probably involved in the development of parkinsonian manifestations in HE, but its role in other neurologic manifestations is uncertain (30). The concentration of manganese is elevated in the plasma of patients with cirrhosis and in the brain of patients who die with HE. Hypermanganesemia is the result of portosystemic shunting and a reduction in biliary excretion (31). Patients with cirrhosis typically exhibit a hyperintense signal in the globus pallidum (Fig. 20.3) that has been attributed to the preferential accumulation of manganese in the basal ganglia. However, some studies have failed to show a good association between the intensity of the signal in basal ganglia and neurologic manifestations of HE (32). Nevertheless, its similarities to the clinical and radiologic features of manganese intoxication suggest that the increase in manganese level in cirrhosis causes the extrapyramidal signs of chronic HE through mechanisms that impair dopaminergic neurotransmission. The effect of manganese removal on the neurologic signs and symptoms of chronic HE has not been evaluated.

Other compounds A group of potentially neurotoxic compounds of colonic origin has been postulated to affect neurologic function. These include GABA (23), mercaptans, and short-chain fatty acids (8). The concentration of these compounds have been found to be elevated in the plasma of patients and in experimental models of HE, but controversial results and lack of confirmatory data do not support a primary role in HE (Table 20.3).

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▪ Figure 20.3 T1-weighted magnetic resonance image of the brain of a patient with cirrhosis. The patient exhibits a symmetrical hyperintensity of the globus pallidus (arrows).

P.574 Patients with liver failure show an increase in aromatic amino acid levels (e.g., tyrosine, phenylalanine, or tryptophan) and a decrease in branched-chain amino acid levels (e.g., valine, leucine, or isoleucine). It was proposed that this imbalance would enhance the passage of aromatic amino acids through a neutral amino acid carrier into the brain in exchange for glutamine generated from ammonia detoxification (4). The excess of aromatic amino acids would then be channeled in the brain into the synthesis of false neurotransmitters (e.g., octopamine, phenylethanolamine) and serotonin, an inhibitory neurotransmitter. However, this hypothesis, which was the basis for the treatment of HE with branched-chain amino acids, has not been supported by the result of in vivo and postmortem studies. If there is any beneficial effect of the therapy for HE with branched-chain amino acids, it may be through alternative mechanisms (See “Principles of Treatment”).

Table 20.3. Other Compounds that Have Been Involved in the Pathogenesis of Hepatic Encephalopathy

Substance GABA

Pros Increase in plasma levels (33)

Cons GABA not increased in central nervous system (34)

Disturbance in GABAergic neurotransmission (23)

Short-chain fatty

Synergistic effects with ammonia (8)

Lack of correlation between plasma levels and grade

acids

Lactulose decreases the genesis (35)

of HE (36)

Mercaptans

Synergistic effects with ammonia (37)

Plasma levels found in HE are not neurotoxic (38) Lack of correlation between plasma levels and grade of HE (39)

Aromatic amino

Increase in plasma levels (40)

acids

Lack of correlation between plasma levels and grade of HE (41) Normal blood–brain barrier permeability to amino acids (42) False neurotransmitters not found in human brain (43)

GABA, γ-aminobutyric acid; HE, hepatic encephalopathy.

Abnormalities in the Central Nervous System Astrocytes Experimental and pathologic evidence points at astrocytes as the prominent cells affected in HE (44). No significant or consistent morphologic changes have been identified in neurons or other cells of the CNS. The distinctive morphologic alteration is the Alzheimer type II astrocytic change, which is characterized by a cell with enlarged, pale nuclei with peripheral margination of chromatin and often prominent nucleoli (Fig. 20.4). Results of microscopic studies of specimens from humans and of experimental preparations suggest that the astrocytic changes can be explained by the existence of cellular swelling. Astrocytes occupy one third of the volume of the cerebral cortex. Their foot processes surround brain capillaries, where they contribute to blood–brain barrier function, and neurons. This anatomic organization forms a syncytium, where critical metabolic supportive functions involved in the maintenance and regulation of the extracellular microenvironment, such as uptake of ions and neurotransmitters, influence neuronal excitability and neurotransmission. A specific P.575 astrocyte function is the detoxification of ammonia through the amidation of glutamate to glutamine. An increase in intracellular

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osmolality as a result of glutamine accumulation underlies the genesis of astrocytic swelling in HE (46). These findings have led to the proposal of HE being the clinical manifestation of a gliopathy, in which neuronal dysfunction develops as the result of astrocytic abnormalities (6). Several mechanisms by which abnormal glial cells could influence neuronal function have been postulated:

▪ Figure 20.4 Alzheimer type II astrocyte showing nuclear enlargement and clearing (arrow), with the chromatin displaced to the periphery. Two adjacent relatively normal astrocytes are also present. A nearby neuron (N) is normal (45). (From Norenberg MD. Hepatic encephalopathy. In: Kettenmann H, Ransom BR, eds. Neuroglia. New York: Oxford University Press, 1995:950–963, with permission.)

▪ Figure 20.5 Abnormalities of glutamate neurotransmission in hepatic encephalopathy. Glutamate released from the presynaptic neuron is again taken up into the perineuronal astrocyte through the glutamate transporter (GLT-1) and glutamate–aspartate transporter (GLAST). Glutamate receptors are expressed in neurons (N-methyl-D-aspartate [NMDA], αamino-3-hydroxy-5-methylisoxazole-4-propionic acid [AMPA], kainic acid [KA], or metabotropic subtypes [M]) and astrocytes (AMPA, KA). CSF, cerebrospinal fluid; EAAC1, excitatory amino acid carrier 1. (Adapted from Butterworth RF. The neurobiology of hepatic encephalopathy. Semin Liver Dis 1996;16:235–244.)

1. Interaction with glutamate reuptake (Fig. 20.5) (47). In experimental models, glial reuptake of the glutamate released from presynaptic neurons is likely to be decreased. Downregulation of glutamate transporters located in the plasma membrane of astrocytes (i.e., glutamate transporter-1, glutamate-aspartate transporter) can be reproduced in astrocyte cultures exposed to ammonia. A decrease in reuptake will result in an increase in brain extracellular glutamate levels, with subsequent effects on glutamatergic neurotransmission. 2. Activation of the PTBRs (Fig. 20.6) (44). An increase in the number of PTBRs has been observed in the brain of patients who died with HE and can be reproduced experimentally after administration of ammonia. Activation of PTBRs by different ligands, such as ammonia and diazepam-binding inhibitor, results in an increase in the synthesis of neurosteroids (e.g., pregnenolone, dehydroepiandrosterone), powerful ligands of the neuronal GABA A receptor, thereby affecting GABAergic neurotransmission. 3. Metabolic consequences of cellular swelling (6). The cellular hydration state regulates cell function and gene expression. Swelling of astrocytes P.576 activates extracellular regulated protein kinases, elevates calcium concentration, and affects multiple ion channels and amino acid transport. Oxidative stress can be detected in vitro and in vivo (48). All these abnormalities may affect the ability of astrocytes to efficiently uptake or release extracellular ions and neurotransmitters, secondarily affecting glial–neuronal communication.

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▪ Figure 20.6 Abnormalities of γ-aminobutyric acid (GABA) neurotransmission in hepatic encephalopathy. The activation of “peripheral-type” benzodiazepine receptor (PTBR) by ammonia enhances the synthesis of neurosteroids in the mitochondria of astrocytes. Neurosteroids and ammonia may modulate the GABA A receptor and thus contribute to hepatic encephalopathy. BZD, benzodiazepine. (Adapted from Butterworth RF. The neurobiology of hepatic encephalopathy. Semin Liver Dis 1996;16:235–244.)

Table 20.4. Main Abnormalities of Neurotransmission Described in Hepatic Encephalopathy and Their Possible Consequences

System Glutamate

Findings

Possible consequences

Decrease in total brain glutamate level (50)

Impaired mental function

Increase in extracellular glutamate level (49)

Brain edema

Decrease in glutamate transporter levels (51)

Convulsions

Decrease in glutamate receptor levels (49)

GABA

Signs of increased GABAergic tone (23)

Decrease of consciousness

Positive response to flumazenil (27) Increase in benzodiazepine receptor ligand levels (23) Activation of peripheral-type benzodiazepine receptor (44) Increase in neurosteroid levels (44)

Serotonin

Increase in the metabolism of serotonin (52)

Behavioral abnormalities

Dopamine

Decrease of dopamine receptor levels (53)

Extrapyramidal manifestations

Increase in degradation of dopa (54) Improvement of extrapyramidal signs with dopa (55)

Opioid

Increase in the sensitivity to morphine (56)

Behavioral abnormalities

Increase in endogenous opioids (57)

Histamine

Increase in histamine receptors (58)

Circadian rhythm abnormalities

Nitric Oxide

Decrease in cerebellar cyclic guanosine monophosphate (59)

Learning impairment

GABA, γ-aminobutyric acid.

Neurotransmitter systems HE, as other forms of metabolic encephalopathy, appears to occur as a result of abnormalities in neurotransmission (5). This hypothesis is supported by its potential reversibility and by the lack of neuronal damage. Multiple abnormalities of neurotransmitter systems have been described (Table 20.4). Glutamate neurotransmission is clearly disturbed in animal models of HE (49), where it appears to have a role in the pathogenesis of HE (Fig. 20.7). However, supportive human data arise mostly from autopsied samples (50), and pharmacologic manipulation of glutamatergic neurotransmission has not been attempted. The improvement of neurologic manifestations after the administration of a drug that interacts with an individual transmitter system is an important argument to support a pathogenic role for that system. The first attempt to normalize the abnormalities of neurotransmission arose from the false neurotransmitter hypothesis. The notion was to restore the abnormalities in the profile of plasma amino acids and the transport of amino acids across the blood–brain barrier by administering branched-chain amino acids. Subsequent therapeutic attempts have been focused on the brain itself and include stimulation of dopaminergic transmission with

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bromocriptine or levodopa (55) and blockage of GABA-inhibitory neurotransmission with flumazenil (27). The results have not been remarkable, highlighting the complexity of a paradigm in which several neurotransmitter systems are simultaneously affected. Still, these attempts indicate it may be possible to treat HE using drugs that act in the brain in addition to measures that decrease the plasma level of a putative toxin.

▪ Figure 20.7 Molecular views of four types of glutamate receptors. Two heteromeric receptors are shown, the N-methyl-Daspartate (NMDA) and α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptors, and two metabotropic receptors, the L-AP 4 and trans-(±)-1-amino-cyclopentane-1,3-dicarboxylate (ACPD) receptors. Competitive antagonists of each receptor are boxed. AMP, adenosine monophosphate; cAMP, cyclic adenosine monophosphate; GMP, guanosine monophosphate; cGMP, cyclic guanosine monophosphate; PLC, phospholipase C; PIP 2 , phosphatidylinositol-4,5-bisphosphate; PCP, purinecytosine permease; DAG, diacyl glycerol; IP 3 , inositol triphosphate; Glu, glutamine; PDE, phosphodiesterase; DCK, 5,7-dichlorokynurenic acid; Gly, glycine (60). (From Dingledine R, McBain CJ. Excitatory amino acids. In: Siegel GJ, Agranoff BW, Albers RW, et al. eds. Basic neurochemistry, 5th ed. New York: Raven Press, 1994:367–387, with permission.)

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Energy abnormalities The brain is the tissue with the highest energy requirements of the body and depends entirely on the process of glycolysis and respiration within its own cells to fulfill its energy demands. In HE in humans, a decrease in consumption of oxygen and glucose is accompanied by a parallel decrease in cerebral blood flow (61). These energy abnormalities are not homogeneous across the brain, with basal ganglia exhibiting a different pattern from the cortex (20). Some studies with humans have shown focal reductions of glucose utilization that are related to specific neurologic manifestations (62). However, the findings cannot separate whether the decrease is the cause or the consequence of the encephalopathy. The current interpretation is that, as in other metabolic encephalopathies, the decrease in energy consumption is secondary to the decrease in demand. As observed in some patients with high cerebral blood flow, especially among those with fulminant hepatic failure, an increase in supply does not improve the mental state (63). Ammonia may impair glycolysis because it inhibits α-ketoglutarate dehydrogenase, the rate-limiting enzyme of the tricarboxylic acid cycle (22). However, the histologic features are different from those observed in hypoglycemia or hypoxia. In experimental preparations, energy deficits are only observed after prolonged periods of coma. Results of magnetic resonance spectroscopy performed on humans suggest that there are no significant deficits in the generation of high-energy compounds in the brain (64).

Brain edema Brain edema is a complication of fulminant hepatic failure, which can progress to intracranial hypertension and death (Fig. 20.8). Brain edema has been frequently regarded as a distinct entity, dissociated from the neurologic features of HE. However, several lines of evidence relate brain edema to HE (46). Although intracranial P.578 hypertension is a common problem in patients with fulminant hepatic failure in coma, the development of high intracranial pressure (ICP) in patients with cirrhosis in deep coma is only occasionally documented (65).

▪ Figure 20.8 A: A pie chart separating the three compartments in the brain according to their relative volume: Brain tissue (70%), cerebrospinal fluid (CSF) (25%) and blood volume (5%). B: In an early stage of increase in brain volume, large

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changes in volume result in small changes in intracranial pressure (ICP); at a later stage, brain compliance is reduced, and small changes in volume cause large changes in pressure.

One important limitation is the assessment of brain edema in these circumstances. Standard neuroimaging techniques are insensitive to detect increases in brain water even when intracranial hypertension is already present. MRI provides multiple indirect evidences of an increase in brain water (66). Magnetization transfer imaging is a technique based on the transfer of magnetization between free protons in water and bound protons associated with macromolecules that allows an estimation of the amount of free water through the calculation of the magnetization transfer ratio (MTR). Brain edema causes a decrease in MTR, a result that is well documented in cirrhosis (67). In addition, the development of low-grade brain edema in cirrhosis is supported by diffusion weighted imaging (68) and magnetic resonance spectroscopy (69). The corticospinal tract, which corresponds to the first neuron of the voluntary motor pathway, appears more vulnerable to edema and functional impairment (70). The parallel improvement of magnetic resonance abnormalities and neurophysiologic disturbances after liver transplantation supports the hypothesis that astrocytic edema may cause secondary neuronal dysfunction (6). Brain edema appears to originate from the accumulation of glutamine, the product of ammonia metabolism in astrocytes (46). The osmotic effects of an acute increase in glutamine concentration appear to overcome the compensatory capacity of astrocytes, cells that are swollen in neuropathologic preparations. Brain edema has been described in all situations of acute hyperammonemia and has been associated with plasma levels of ammonia in fulminant hepatic failure (71). In the experimental setting, brain swelling secondary to ammonia infusion can be prevented with the administration of an inhibitor of the synthesis of glutamine. Other factors, such as hyponatremia, may enhance the effects of ammonia on brain swelling (72). In fulminant hepatic failure, an additional factor that plays an important role in the development of intracranial hypertension is the presence of abnormalities of cerebral circulation. Cerebral vasodilatation and loss of autoregulation are characteristic findings in fulminant hepatic failure (63). The mechanism that causes the abnormalities of cerebral circulation has not been fully elucidated. They appear to arise from a signal generated in the brain. Indeed, measures that decrease cerebral vasodilatation are of clinical benefit for patients with severe intracranial hypertension (73). In addition to differences in the cerebral circulation and in the rate of exposure of the brain to ammonia, patients with cirrhosis may activate compensatory mechanisms that counteract osmotic changes in the brain (46). Those with hyponatremia are at higher risk for the development of intracranial hypertension.

Factors that Favor the Effects of Toxins Precipitating factors Several factors are known to precipitate an episode of HE in stable patients with cirrhosis (Table 20.5). They exert their effects through an increase in the generation of putative toxins, impairment in liver function (resulting in enhanced portosystemic shunting and P.579 larger delivery of toxins to the brain), or enhancement of the effects of the toxins on the CNS. In some cases the mechanisms that explain the action of the precipitating factor seem obvious (i.e., worsening liver function in acute hepatitis). In other cases, there are multiple factors acting as coprecipitants.

Table 20.5. Precipitating Factors for Hepatic Encephalopathy

Associated Precipitating factor Sepsis

Possible effects

coprecipitant

Mechanism of action

Increase in blood ammonia level

Protein catabolism

Azotemia

Enhancement of the effects of

Activation of cytokines

Arterial hypotension

putative toxins on the CNS

Gastrointestinal

Impairment in liver function

Hepatic hypoperfusion

Infection

bleeding


Nitrogen load

Anemia

Disturbances of plasma amino

Arterial hypotension

acids

Hypokalemia


Ammonia generation

—

Azotemia


Ammonia generation

—

Dehydration

Increase in blood ammonia


Hypokalemia Azotemia

Diuretics


Hypokalemia

—

Azotemia Dehydration

Acute hepatitis


Liver injury

Enhancement of effects on the CNS

Activation of cytokines

Surgery



Anesthetics

Constipation


Ammonia generation by enteric

—

flora

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Large protein intake


Nitrogen load

—

Psychoactive drugs

Enhancement of effects on the CNS

Activation of inhibitory

—

neurotransmission

CNS, central nervous system.

Infection and inflammation have been postulated to play an important synergistic role in the pathogenesis of HE (9). Possible mechanisms by which such effects may be mediated include activation of vagal afferents at the site of inflammation, binding of cytokines and/or inflammatory cells to receptors in cerebral endothelial cells with subsequent transduction of signals into brain, and direct access of cytokines into brain tissue to sites lacking blood–brain barrier (such as the circumventricular organs). Cytokines may increase blood–brain barrier permeability to ammonia, resulting in the generation of intracerebral mediators, such as nitric oxide and prostanoids, and cause astrocytic swelling (6,74). A systemic infection will also impair renal function, increasing circulatory urea levels, with subsequent colonic generation of ammonia through urease-containing bacteria. Treatment of infection has been shown to have a direct impact on neuropsychological function in patients with cirrhosis (75).

Portosystemic shunts Portosystemic shunting allows the access of gut-derived toxins into the systemic circulation. There are three different types of portosystemic shunts: (a) Congenital shunts without significant liver disease, (b) large spontaneous shunts in cirrhosis, and (c) procedural shunts. Congenital shunts are rare conditions that connect the portal with the systemic circulation and may cause neurologic manifestations compatible with HE without abnormalities in the liver parenchyma (76). Different morphologic types have been described. They may be single or multiple and be located intrahepatic or extrahepatic. Congenital shunts may be associated with hypoplastic portal vein branches or even the absence of portal vein (patent ductus venosus or Abernethy malformation). Associated abnormalities in the portal branches may lead to some degree of parenchymal atrophy. Clinical manifestations present very early in life or in the sixth or seventh decades, suggesting an age-dependent sensitivity of the CNS to develop HE. Large portosystemic shunts may develop in some patients with cirrhosis and favor the development of persistent HE (77). These spontaneous shunts can decrease portal pressure, and the patients seldom have significant portal hypertension. These shunts may have different extrahepatic locations. Among the different shunts, large splenorenal shunts are those more commonly associated with chronic HE because they lead to marked portal flow steal (78). Procedural shunts are secondary to transjugular intrahepatic portosystemic shunt (TIPS) or other surgical intervention (79). The frequency of postshunt encephalopathy depends on the type of shunt and the susceptibility of the individual. Approximately, one third of patients subjected to a TIPS procedure will P.580 develop encephalopathy. Nonselective portosystemic shunts (i.e., portocaval, mesocaval) produce more encephalopathy than do selective shunts (i.e., distal splenorenal) in patients with nonalcoholic cirrhosis. However, selectivity of splenorenal shunts is lost in the long term. Elderly patients and those with poor liver function are at higher risk for postshunt encephalopathy. However, there is no hepatic functional test that confidently identifies individuals who will develop HE. Closure of TIPS is associated with improvement of HE (80).

Increased brain susceptibility Patients with cirrhosis prone to HE have an increased susceptibility to the effects of different psychoactive drugs, such as morphine, antidepressants, or benzodiazepines. This increased susceptibility is not explained simply by pharmacokinetic changes induced by liver failure (81). Hypersensitivity to psychoactive drugs may be mediated by changes in neurotransmission secondary to the disease of the liver, such as underlying abnormalities in benzodiazepine receptors. Additional factors could be the presence of abnormalities at the level of the blood–brain barrier and/or cerebral blood flow. General derangements of blood–brain barrier permeability do not appear to be present in HE (46). However, selective increments in permeability may occur, as has been shown for ammonia in patients with minimal HE (12). Comorbid conditions, which are common in patients with cirrhosis, such as alcoholism or dilutional hyponatremia, as well as advanced age, may facilitate the development of HE because of their direct effects on brain function.

Clinical Features The Acute Episode of Encephalopathy An acute episode of HE is characterized by the development of an acute confusional syndrome that includes impaired mental state, neuromuscular abnormalities, fetor hepaticus, and hyperventilation (1). Variability is an important feature; the clinical manifestations may fluctuate rapidly and oscillate from mild confusion to deep coma. The onset is usually abrupt; HE develops over hours to days. Most patients do not have significant neurologic manifestations before the onset of the acute episode of HE, unless they had persistent HE. The evolution of an acute episode of HE tends to parallel the course of liver function or the removal of the precipitating factor. Prolonged episodes of HE occur among patients with terminal liver failure. Patients usually recover from HE without major neurologic deficits and are able to return to previous activities. Impairment of consciousness initially manifests as subtle changes of personality or disturbances in the circadian rhythm of sleep and wakefulness (i.e., insomnia during the night, somnolence during the day). As HE progresses, the manifestations include inappropriate behavior, disorientation, confusion, slurred speech, stupor, and coma. Some patients may experience nausea and vomiting, especially if there is rapid evolution into coma. Asterixis is a characteristic feature of HE that represents the failure to actively maintain posture or position (1). Asterixis is caused by abnormal function of diencephalic motor centers that regulate the tone of the agonist and antagonist muscles normally involved in maintaining posture (82). The classic method of eliciting asterixis is by dorsiflexion of the patient's hand, with the arms outstretched and fingers separated. The postural lapse that occurs consists of a series of rapid, involuntary, flexion–extension movements of the wrist. Asterixis may be observed during any sustained posture: Tongue protrusion, dorsiflexion of the foot, or fist

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clenching. Asterixis is not exclusive to HE and can occur in other metabolic or structural encephalopathies (e.g., renal failure, hypercapnia, stroke affecting basal ganglia). Asterixis does not occur in early or advanced HE. In coma, asterixis disappears, but the patient may exhibit signs of pyramidal involvement, such as exaggerated deep tendon reflexes, hypertonia, or extensor plantar responses. Transient decerebrate posturing and abnormal ocular movements may occur in deep coma. Fetor hepaticus is a peculiar pungent odor of the breath that is often regarded as a component of HE. This odor is attributed to dimethylsulfide, a volatile sulfur compound, that can be identified in the breath and serum of patients with cirrhosis (39). The presence of fetor hepaticus is not constant; patients with cirrhosis but not HE can have this condition. Hyperventilation is also frequent, especially among patients with advanced HE, and has been interpreted as a compensatory mechanism that decreases the entrance of ammonia into the brain through a decrease in arterial pH. It has also been related to elevated levels of estrogens and progestogens (83).

The Patient with Chronic Encephalopathy Chronic encephalopathy encompasses two different situations: (a) The patient with relapsing episodes of HE and (b) the patient with persistent neurologic manifestations. This differentiation highlights the more prominent clinical presentation, but in practice both situations are difficult to separate. Some patients initially P.581 have relapsing episodes and later have persistent symptoms. A patient with purely relapsing HE or purely persistent HE is rare. Furthermore, symptoms tend to fluctuate after the institution of therapeutic measures or the occurrence of precipitating events. Relapsing episodes may be due to precipitating factors, but in most cases are spontaneous or related to the discontinuation of medication. A history of constipation is commonly elicited. The course of the acute episode does not differ from the one previously described, except a tendency for an abrupt onset and resolution. Between episodes, the patient can be perfectly alert and not show any sign of cognitive dysfunction. However, a careful neurologic examination and neuropsychological tests may reveal abnormalities. Mild parkinsonian signs, characterized mostly by bradykinesia without tremor (84), are probably the most common manifestation between episodes. Persistent HE refers to those manifestations that do not reverse despite adequate treatment. In most patients with cirrhosis and prior episodes of acute HE and advanced liver failure, a careful neurologic examination will reveal multiple mental and motor abnormalities. Most of these abnormalities are subtle, such as increased muscle tone, reduced mental or motor speed, dysarthria, hypomimia, lack of attention, or apraxia. Psychometric tests may be helpful in describing and quantifying the degree of impaired mental function. Persistent HE is considered severe when it impairs daily activities. The most characteristic manifestations of severe chronic HE are dementia, severe parkinsonism, or myelopathy in combination with other manifestations of neurologic involvement (e.g., ataxia, dysarthria, gait abnormalities, or tremor). This clinical picture is seldom seen nowadays because of the availability of liver transplantation and the limited number of patients who undergo surgical portosystemic shunts. Patients with hepatic dementia tend to have fluctuating symptoms with periods of improvement and a subcortical pattern. The initial manifestations are attentional deficits, visuopractic abnormalities, dysarthria, and apraxia. Those with hepatic parkinsonism may resemble Parkinson's disease, except for a symmetrical presentation and lack of significant tremor. Hepatic myelopathy (85) is characterized by a progressive spastic paraparesis accompanied by hyper-reflexia and extensor plantar responses. Only a few patients have sensory symptoms or incontinence. The pathogenetic mechanisms of these complications are obscure. They have associated neuronal loss—in case of dementia—and demyelination along the pyramidal tract—in case of myelopathy. Although these lesions are difficult to reverse, there are descriptions of improvements after liver transplantation (86), a challenge to the notion of irreversibility. The term hepatocerebral degeneration has been occasionally used to describe such patients. However, this is a neuropathologic diagnosis applied to those patients whose brains exhibit substantial and irreversible loss of gray matter in the cortex and basal ganglia. It is preferable not to use it to describe the clinical picture.

The Brain in Fulminant Hepatic Failure The clinical picture of HE in acute liver failure parallels that of an acute episode of HE: An acute confusional syndrome that evolves into coma. However, in acute liver failure, brain edema leading to intracranial hypertension and abnormalities of brain perfusion is critical (87). Brain edema does not result in clinical manifestations unless intracranial hypertension is present because the displacement of brain tissue is the factor that results in neurologic symptoms. Intracranial hypertension may manifest as decerebrate rigidity, myoclonus, seizures, mydriasis, bradycardia, or arterial hypertension (Cushing's reflex). However, the diagnosis of intracranial hypertension based on clinical signs is unreliable because they can be absent with pressures as high as 60 mm Hg (88) and are difficult to monitor because these patients are intubated and paralyzed when they are in coma. A major consequence of intracranial hypertension is the effect on cerebral perfusion. The maintenance of cerebral blood flow is critical to ensure an adequate supply of oxygen. The driving force in maintaining a stable blood flow is the cerebral perfusion pressure, the arithmetical difference between mean arterial pressure and ICP. When cerebral perfusion pressure is less than 40 mm Hg, structural tissue damage from brain ischemia may ensue. In spite of low cerebral blood flow, an occasional patient may recover from this situation without irreversible brain damage. Another consequence of intracranial hypertension is the mechanical compression of neighboring structures. The increase in pressure causes displacement of brain tissue, resulting in herniation and direct compression of the temporal lobe or the cerebellum. Brain stem compression can result in sudden respiratory arrest and circulatory collapse.

Minimal Hepatic Encephalopathy Minimal HE, also referred by the terms latent or subclinical, is a mild dysfunction of brain function that cannot be detected by standard clinical examination (3,89). This label was originally applied to a group of individuals who performed abnormally on psychometric tests but had essentially normal findings on clinical examination. Psychometric tests are more sensitive than clinical observation, as shown in other neuropsychiatric diseases, such as dementia. P.582 Other techniques (e.g., electroencephalogram [EEG]), evoked potentials, or neuroimaging) that are more sensitive than clinical examination to reveal neurologic impairment have also shown a stage of minimal dysfunction, which is understood as part of a continuous disorder that has several levels of severity, minimal HE being the mildest expression of HE. This interpretation is supported by the observation of amelioration of minimal HE after using the same therapeutic measures as those used against overt HE (90) and the relationship between minimal HE, ammonia levels, and liver function (91). The diagnosis of minimal HE is arbitrary and can be performed with neuropsychological or neurophysiologic tests. The most characteristic deficits are in motor and attentional skills (92). Learning impairment, which has also been described in experimental models (59), appears to be the consequence of attention deficits (93). The depth of the psychometric and the clinical examination necessary to diagnose minimal HE is not defined. The frequency of the diagnosis is variable (30% to 84% of patients), depending

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on the characteristics of the population being studied and the extent of the psychometric evaluation. Some attempts have been made to develop practical tools on the basis of the design of short batteries of neuropsychological tests, such as the Psychometric Hepatic Encephalopathy Score (PHES) (94). However, these batteries have not been fully standardized and their use is still investigational. Critical flicker frequency, a neurophysiologic tool, has been proposed as a practical test to assess low-grade encephalopathy (95). The importance of establishing the diagnosis of minimal HE is unknown. Some studies have highlighted that minimal HE may have an adverse impact on the ability to perform daily activities and on health-related quality of life (96). However, many subjects are able to compensate for these deficits (89). From a practical point of view, a psychometric evaluation may be adequate in those individuals whose occupations demand attentional and motor abilities. A report of impaired driving in patients with minimal HE (97) suggests the need to develop a therapeutic program for such individuals. Benefits of treatment, as assessed by monitoring the neuropsychological response, should be weighed against secondary side effects. There are no data on the effects of therapy on health-related quality of life. Patients with cirrhosis and minimal HE have a clear tendency to develop overt HE (98). Whether the institution of preventive measures would decrease the risk of the progression to overt encephalopathy has not been evaluated. The presence of minimal HE indicates worse prognosis, especially if associated with high levels of blood ammonia after the administration of glutamine (99). For this reason, liver transplantation should be considered in patients with minimal HE.

Methods for the Assessment of Hepatic Encephalopathy Grading Hepatic Encephalopathy Grading of HE is necessary to assess the evolution of the condition and the response to the effects of therapy. Several methods are based on clinical findings or the combination of neurophysiologic and neuropsychological tests, but the simplest grading of HE is based on clinical findings. The West Haven index is widely used (13). It is based on changes in consciousness, intellectual function, and behavior (Table 20.6). The Glasgow Coma Scale offers a system that monitors consciousness according to simple and more objective parameters. This scale was initially developed for traumatic coma but has gained widespread use for all forms of coma. It is probably more reliable than the West Haven criteria but has the limitation that it is less sensitive in quantifying the mildest forms of HE and is better suited for advanced HE. The portosystemic encephalopathy (PSE) index has been used in many studies to assess the effects of therapeutic measures. This index combines the assessment for mental state, arterial ammonia level, EEG, the number connection test, and estimation of the degree of asterixis. An arbitrary weight of 3 is assigned to the mental state and the other parameters are weighted. Concerns have been raised about the arbitrary scoring system, the inclusion of ammonia (a putative toxin), the feasibility of an arterial puncture, and the assessment of the number connection test in the evaluation of advanced HE. It is generally considered that blood levels of ammonia, although separating groups according to mean values (21), show wide dispersion in individual values and are not useful to predict the severity of HE and monitor the response to therapy (100). A P.583 consensus has been reached indicating that the PSE index is not adequate for clinical follow-up and is not recommended for clinical trials.

Table 20.6. Grading Scale of Hepatic Encephalopathy Based on Change in Mental Status

Grade

Neurologic manifestations

0

No alteration in consciousness, intellectual function, personality, or behavior

1

Trivial lack of awareness, euphoria or anxiety; short attention span

2

Lethargy, disorientation, personality change, inappropriate behavior

3

Somnolence to semistupor, confusion; responds to noxious stimuli

4

Coma, no response to noxious stimuli

From Conn H. & Bircher J. with mild modifications Conn HO. The hepatic encephalopathies. In: Conn HO, Bircher J, eds. Hepatic encephalopathy. Syndromes and therapies. Bloomington, IL: Medi-Ed Press, 1994:1–12.

Neuropsychological Tests The main role of neuropsychological tests is the diagnosis of minimal HE and the assessment of cognitive function in patients with persistent HE. On the basis of the most frequently found abnormalities, several psychometric tests have been proposed to be the most adequate for diagnosing HE (89,92). Neuropsychological tests can be affected by multiple factors. It is important that the neuropsychological assessment takes into consideration these factors. Patients with clear signs of decreased arousal cannot undergo testing. Care is needed to control for comorbidities, visual impairment, or cultural barriers. The test should be adapted to the cultural characteristics of the population being evaluated. Nomograms to compare the results should take into consideration age and, ideally, the degree of education. The patient undergoing testing should be seated in a quiet room with sufficient light. An important limitation of the neuropsychological tests is the practice effect in follow-up evaluation. Results of psychometric tests are affected by learning. Use of parallel versions can lessen this effect, but only few tests have well-standardized versions. Some short batteries specifically developed for HE may be useful for the detection of abnormal cognition. However, they do not substitute a formal neuropsychological evaluation performed by an experienced neuropsychologist. The PHES is a battery of tests specifically developed for the diagnosis of minimal HE (94). Similar to the Mini-Mental State Examination for dementia, PHES can be useful for screening minimal HE. The PHES combines five paper–pencil tests (i.e., line tracing tests, digit symbol test, serial dotting test, number connection test A, and number connection test B) that examine motor speed and accuracy, visual perception, visual– spatial orientation, visual construction, concentration, attention, and, to a lesser extent, memory. The results of the battery are scored according to normograms from a group of healthy controls. Each one of the test scores 0 points when it falls in the ±1 standard deviation (SD) range. A test that falls in the range more than 1 SD is scored +1 point and for less than -1 SD, -2 SD, -3 SD range, the tests are scored with -1, -2, or -3 points, respectively. Thereby, the subjects could achieve between +6 and -18

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points. A pathologic test result (diagnosis of minimal HE) is set at -4 points.

Neurophysiologic Tests A large number of different neurophysiologic tests have been proposed for the diagnosis and quantification of HE. Reports for and against the specificity of electrophysiologic changes have been published (101,102). These tests are most useful in documenting cerebral dysfunction in difficult cases and possibly in monitoring response to therapy. They have the advantage of not being influenced by learning effects. Therefore, they may be better suited for assessing effects of treatment than neuropsychological tests, especially for advanced stages of HE. For minimal–mild HE, neurophysiologic tests do not give information about behavioral consequences, in contrast to the insight provided by neuropsychological tests. The standard EEG shows slowing of the frequency from the normal 8 to 13 Hz to the delta range below 4 Hz. The change usually commences in the frontal or central regions and progresses posteriorly. High-voltage, low-frequency (1.5 to 3 Hz) waves with triphasic appearance have been considered characteristic of HE. However, they have been described in a variety of forms of metabolic encephalopathy and are not specific for HE. Several stages of evolution of EEG changes have been described in HE, and a fair correlation with clinical stages and ammonia levels has been observed. The simplest EEG assessment is to grade the degree of abnormality of the conventional tracing. Computer-assisted frequency analysis of the EEG includes evaluation of the mean dominant frequency and the power of a particular EEG rhythm. Minor changes in the dominant frequency occurs in patients with minimal HE (91). Evoked responses are externally recorded potentials reflecting discharges through neuronal networks after exposure to specific stimuli (102). Depending on the type of stimulus and the pathway analyzed, they could be visual, somatosensory, or acousticevoked potentials. Event-related potentials using different stimuli represent an endogenously task-related cortical response reflecting the neural pathway involved in awareness, learning, and decision-making processes. Event-related potentials, such as the P300-evoked potential, requires patient cooperation and well-trained operators. Evoked potentials and event-related potentials are considered more sensitive than the conventional EEG for the diagnosis of mild forms of HE. They may be useful for assessing the presence of minimal or mild HE in patients with cirrhosis who have memory loss or other mental symptoms.

Neuroimaging At autopsy, the brains of patients with cirrhosis who have died from HE do not show major anatomic abnormalities, except for various degrees of atrophy. Therefore, neuroimaging studies that exclusively assess the morphologic structure of the brain, such as computed tomography (CT) scan, do not detect specific abnormalities in HE. Brain atrophy, which is depicted with CT scan, is more common in patients with P.584 long-standing cirrhosis and chronic HE (103). However, brain atrophy is not a specific abnormality of HE and may be related to factors other than HE (e.g., alcoholism, age, or comorbid conditions). Furthermore, as in other neurodegenerative diseases, brain atrophy is not associated with neuropsychological performance (104). Conventional neuroimaging techniques are insensitive to the detection of brain swelling that may develop in some patients with cirrhosis and frequently complicates HE in acute liver failure (105). No studies have been able to find a neuroimaging correlate of hepatocerebral degeneration (cortical laminar necrosis and polymicrocavitation at the corticomedullary junctions and in the striatum). Magnetic resonance imaging (MRI) and spectroscopy allow the acquisition of data on cerebral metabolic function that are otherwise not available (64). Proton MRI shows a typical pallidal hyperintensity on T1-weighted images (Fig. 20.3). This abnormality is most frequently seen in patients with cirrhosis and severe liver failure or long-standing portosystemic shunts and is absent or only minimally present in patients with well-compensated cirrhosis and unimpaired neuropsychiatric function. It can be also present in patients with congenital shunts or portal thrombosis and normal liver function (106). No direct correlation between the magnitude of pallidal hyperintensity and the grade of HE have been found, but some studies have related pallidal hyperintensity to parkinsonian manifestations (107). Because of radiologic similarities to manganese intoxication, it has been proposed that pallidal hyperintensity is the consequence of the preferential deposition of manganese in the basal ganglia. The deposition of manganese in brain tissue would be secondary to portosystemic shunting and might be involved in the parkinsonian symptoms found in persistent HE.

▪ Figure 20.9 Proton magnetic resonance spectroscopy. White matter spectrum representation from a healthy control (A) and a cirrhotic patient with chronic HE and mild neuropsychological impairment at the time of the study (B). The most significant peaks correspond to myoinositol (mIns, 3.55 ppm), choline (Cho, 3.2 ppm), creatine (Cr, 3.0 ppm), glutamine/glutamate (Glx, 2.15 to 2.50 ppm), and N-acetyl aspartate (NAA, 2.0 ppm). The spectrum of the patient with cirrhosis shows a marked decrease in mIns and an increase in Glx. (From Cordoba J, Hinojosa C, Sanpedro F, et al. Usefulness of magnetic resonance spectroscopy for diagnosis of hepatic encephalopathy in a patient with relapsing confusional syndrome. Dig Dis Sci 2001;46:2451–2455, with permission.)

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Proton magnetic resonance spectroscopy allows the assessment of several brain metabolites (e.g., glutamine, glutamate, myoinositol) that may be related to the pathogenesis of HE. The level of glutamine, the product of ammonia metabolism in astrocytes, is characteristically increased in brain tissue. Although glutamine is considered neuronally inactive, changes in its concentration may affect neuronal–astrocytic trafficking and affect glutamate neurotransmission (44). The concentration of P.585 glutamine in CSF, an indicator of its level in brain tissue, has been correlated to the stage of HE. Unfortunately, the standard available systems in which magnetic fields of 1.5 T are used do not allow a separation between the peaks of glutamine (moderately high increase in HE) and glutamate (mild decrease in HE). Myoinositol has an important role in osmotic regulation in astrocytes. The decrease in brain myoinositol content found by spectroscopy has been corroborated in experimental preparations and has been attributed to a compensatory response to the increase in intracellular osmolality caused by the increased concentration of glutamine (46). Although the technique is insensitive to mild changes in the concentration of metabolites, the abnormalities found with spectroscopy (Fig. 20.9) have been related to neuropsychological impairment and liver function (69). The role of proton magnetic resonance in the diagnosis of HE has not been investigated. Nevertheless, a completely normal study in a patient suspected to suffer from HE is a strong argument against this diagnosis. Regional distribution of radionuclides in the brain has been used to study cerebral blood flow, oxygen and glucose consumption, neurotransmitter utilization, and availability of neuronal receptors. The results of some of these studies are controversial (64). Although they may help in understanding the pathogenesis of HE, radionuclide studies are not adequate for diagnostic purposes.

Principles of Treatment HE is a manifestation of severe liver failure; its treatment cannot be separated from the treatment of liver failure. Nevertheless, several measures specifically designed to manage HE appear to be beneficial. The effects have not been evaluated by well-designed randomized clinical trials including a large number of patients. Study design is especially complex in this condition because the clinical course of HE tends to resolve and relapse spontaneously in many cases. The concurrence of other disorders (e.g., anemia, electrolytic disturbances, fever, severe infection, or alcoholic injury) are confounding factors that complicates the assessment of the neurologic manifestations. For these reasons, almost all modalities of therapy have been criticized. In fact reexamination of the results obtained in available trials have questioned the evidence base for current therapies (108). Despite these limitations, critical reappraisal of available data and the clinical experience render it possible to devise a rational approach to the management of HE.

Nutrition Classically, the recommendation for patients with HE has been to restrict dietary protein intake. The extent of the restriction will depend on the degree of HE, being more marked for severe HE. Many investigators have recommended withholding all protein intake and subsequently increasing intake in increments to maximal clinical tolerance (109). This recommendation has been criticized (110). Only one randomized study has investigated the effects of protein restriction on the outcome of HE (111). In this study 30 patients admitted for an episode of HE received progressive amounts of proteins (from 0 to 1.2 g/kg per day) or normal protein amounts (1.2 g/kg per day) from the beginning. The diet was administered through nasogastric tube for 2 weeks and HE was assessed, blinded for the group of treatment. The main result of the study was that there were no differences in the outcome of HE; the normal protein diet was metabolically more adequate. Therefore, restriction of proteins in the diet does not appear to have any beneficial effect for episodic HE. Protracted nitrogen restriction may be harmful, as witnessed in patients with acute alcoholic hepatitis (112). Severe malnutrition, which is common among patients with cirrhosis, is associated with a poor short-term prognosis. Although avoiding intake of large amounts of protein may be advantageous for reducing the levels of toxins involved in HE, restriction may worsen liver function and increase the risk of death. A positive nitrogenous balance may improve encephalopathy by promoting hepatic regeneration and increasing the capacity of the muscle to detoxify ammonia. For these reasons the current recommendation is to avoid restrictions of dietary protein (110). Improvement in nutritional status in patients with cirrhosis and encephalopathy is difficult. A high protein intake (1.2 g/kg per day) may be necessary to maintain nitrogen balance. However, in a classical study (109) the investigators related the intake of increasing quantities of protein to the precipitation of HE. Modifying the composition of the diet and increasing its calorie/nitrogen ratio may improve tolerance to protein. At isonitrogenous levels, vegetable and dairy products cause less encephalopathy than does meat (113). Differences in amino acid composition and in the ratio of carbohydrates to total protein could explain these effects. A high calorie to nitrogen ratio, which is characteristic of casein-based and vegetable-based diets, reduces gluconeogenesis and has anabolic effects on the utilization of dietary proteins. The benefits of vegetable-based diets are also related to the presence of nonabsorbable fiber that is metabolized by colonic bacteria. Fiber increases the elimination of nitrogen products in stool, probably through a similar mechanism to that of nonabsorbable disaccharides. Branched-chain amino acids were promoted as a means of correcting the imbalance in the plasma amino acid profile, which was thought to be involved in the pathogenesis of HE. However, clinical trials using P.586 branched-chain amino acids have not shown major beneficial effects for episodes of HE and only mild effects for chronic HE (Table 20.7). Branched-chain amino acids do not show significant effects on survival. Critical reviews of the published studies highlight the inadequate design of most studies. Considerations of cost-effectiveness indicate that branched-chain amino acids should not be used outside clinical trials (114). They show anticatabolic effects in patients with chronic liver diseases, probably because of their ability to serve as an energy substitute for muscle and because of their actions on muscle protein synthesis and degradation. This nutritional effect may result in an improvement of liver function and a better clinical outcome, as shown in a multicenter trial performed in Italy that included patients with advanced cirrhosis, most of them without prior HE (115).

Table 20.7. Overview of Randomized Controlled Trials of Branched-Chain Amino Acids for Hepatic Encephalopathy

Type of hepatic Treatment

Control

BCAA IV +

Lactulose +

glucose 20%

glucose 20%

encephalopathy Acute

Effects on Trial Rossi-

N

Design

Duration

encephalopathy

34

Multicenter

2–4 d

=

65

Multicenter

38°C or 90 beats/minute, tachypnea >20 breaths/minute or Paco2 12 × 109/L or 10% immature neutrophils), and progressive encephalopathy, reducing the chance of OLT and conferring a poor prognosis (189) (Fig. 21.2). Sepsis is a major cause of the SIRS in FHF, and sepsis-related oxidative stress (210) has been shown in rodents to both promote hepatocellular necrosis and inhibit liver cell regeneration (211), upon which spontaneous recovery ultimately depends.

Nutritional Disturbance

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Energy requirements in FHF are increased by up to 60% and are further elevated by complicating infection. Mean energy expenditure has been estimated to be 4.05 kJ/kg per hour. Despite the reduction in functioning liver mass, the metabolic rate is substantially increased (212), in keeping with the marked SIRS that typically accompanies this syndrome. Harris-Benedict predictions are unreliable for estimating energy expenditure in the FHF setting (212). Rapid deterioration in nutritional status, with depletion of muscle and fat stores, is often seen. Impairment of glycogen storage and reduced capacity for gluconeogenesis result in increased breakdown of adipose tissue and muscle consequent to the use of fat and protein as alternative fuel sources (213). However, the predominant factor responsible for the exaggerated whole body protein degradation is likely reduced hepatic synthesis of insulin-like growth factor-1 (214). Hypoglycemia occurs early in the course of FHF; hypophosphatemia, hypokalemia, and hypomagnesemia are also common, especially in patients who maintain an adequate urine output. As is well described in chronic liver disease, impaired peripheral uptake of glucose consequent to insulin resistance has been documented early in the course of FHF, with insulin sensitivity typically being restored by 2 weeks in patients who survive (215).

Coagulopathy and Bleeding Diathesis Several mechanisms contribute to the coagulopathy associated with FHF, including reduced hepatic synthesis of clotting and anticlotting factors together with consumption of clotting factors and platelets due to disseminated intravascular coagulation (DIC) (216). Although evidence of the latter may be obtained from moderately raised levels of fibrinogen degradation products in a substantial proportion of patients, as has been well demonstrated in experimental animal models, DIC is usually not severe except in acute fatty liver and other pregnancy-related etiologies. The platelet count generally falls progressively day-by-day and is a good marker of disease stage and prognosis. In addition to thrombocytopenia, qualitative platelet defects including increased adhesiveness and impaired aggregation have been described. The degree of prolongation of the prothrombin time is closely related to the severity of liver damage, whereas factor V has the shortest half-life and is, theoretically, the most sensitive index of impaired clotting factor synthesis. Deficiencies of anticlotting factors, such as protein C and antithrombin III, may result in thrombosis of dialysis circuits, despite other manifestations of a bleeding diathesis.

Supportive Management Management in a specialized liver intensive care unit is mandatory for all patients with FHF and more than grade I hepatic encephalopathy. Supportive medical interventions, based on an understanding of underlying pathophysiology, are aimed at maintaining P.613 hemodynamic, cerebral, and renal function; reversing metabolic derangements; preventing or treating complicating bacterial and/or fungal infection; preventing stress ulceration of gastric mucosa; and, where appropriate, treating coagulopathy.

Hemodynamic Interventions to achieve or maintain hemodynamic stability are aimed at optimizing tissue oxygen delivery and consumption parameters. Substantial volumes of colloid, as well as crystalloid, may be required to attain an adequate cardiovascular filling pressure (i.e., pulmonary capillary wedge pressure 8 to 14 mm Hg), given the often profound vasodilatation. In studies performed at King's College Hospital using the Fick method and reported in 1991, N-acetylcysteine infusion was shown to facilitate improved hemodynamic stability in association with mean 46% and 29% increases in global tissue oxygen consumption after 30 minutes of its administration in patients with acetaminophen and other etiologies of FHF, respectively; prostacyclin infusion also improved oxygen delivery and consumption, whereas combined infusions led to a significant increase in oxygen delivery but not consumption compared to infusion of N-acetylcysteine alone (217). A more variable systemic hemodynamic response to N-acetylcysteine was subsequently reported, with clear separation of responders and nonresponders. Overall, a small (6%) early improvement in tissue oxygen consumption that was not sustained throughout a 5-hour period of monitoring was recorded (179). Results of a multicenter study currently under way in the United States are awaited with interest.

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Vasopressor agents are indicated if the mean arterial pressure (MAP) is 3.0 mmol/L or either a postresuscitation or an “early” value >3.5 mmol/L), NPVs were 97% and 99%, respectively. Positive predictive values fell to 79% and 74%, respectively. Additional consideration of blood lactate levels modestly improved the NPV, but positive predictive value remained higher with the initial King's College criteria alone (Table 21.6). Patients with a poor outcome were identified earlier when blood lactate levels were taken into consideration (242).

Other Prognostic Criteria Alternate prognostic indices have been proposed. In a series of 58 patients with acute viral hepatitis, mostly due to HBV infection, who did not undergo transplantation, managed between 1986 and 1990, Bernuau et al. (243) in Clichy found that criteria based on the presence of coma or confusion in association with reduced factor V levels carried positive predictive values and NPVs for death of 82% and 98%, respectively. Clinically apparent encephalopathy was present on admission or subsequently in most, but not all, patients. However, a subsequently reported French study of 81 patients with encephalopathy and nonacetaminophen-related FHF, mostly due to acute viral hepatitis B as in the Clichy series, found a substantially lower ability of the Clichy criteria to correctly identify patients who will survive without OLT (240). Furthermore, the Clichy criteria performed less well in this regard than the King's College criteria when both sets of indicators were applied to the same nonacetaminophen study population, with NPV of 28% and 50%, respectively, on admission, and 36% and 47%, respectively, when reevaluated 48 hours before death (240), a time chosen to approximate the mean waiting time for a donor liver in some contemporary European transplantation series. By contrast, positive predictive values of the two sets of criteria were comparably high (240). Nevens et al. (244), in a Belgian series of 28 patients with nonacetaminophen-related FHF, found that the overall predictive accuracy was modestly increased when both sets of criteria were considered in combination, although the ability to identify patients who will recover spontaneously remained low even in this circumstance. In the only reported comparative assessment of the two sets of criteria in acetaminophen-related FHF, Izumi et al. (245) in a series of 81 patients found that the Clichy criteria performed less well, with lower positive predictive value (49% vs. 92%) and predictive accuracy (56% vs. 83%). The NPV was, however, acceptably high. Taken together, these findings suggest that patients with either acetaminophen- or nonacetaminophen-related FHF who fulfill the King's College criteria and those with nonacetaminophen etiologies meeting the Clichy criteria should be listed for urgent OLT, with the exception of nonacidotic acetaminophen patients, when the encephalopathy grade is not

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advanced. Patients not fulfilling prognostic criteria, especially with FHF unrelated to acetaminophen, should still be considered for OLT and excluded only if serial assessments indicate spontaneous recovery. This issue will likely become even more difficult if the use of temporary liver support based on extracorporeal perfusion or transplantation of hepatocytes or stem cells, as discussed in the subsequent text, is proved to be of benefit. Factor VIII/V ratios; serial prothrombin times; assessment of liver size on computed tomography scanning; liver histology; the Acute Physiology and Chronic Health Evaluation (APACHE) score; sensory-evoked potentials; serum levels of Gc-globulin (vitamin D–binding protein), which is an important liver-derived component of the extracellular actin-scavenging system; and the severity of the SIRS have alternatively been proposed as possible prognostic indices in FHF, with varying degrees of applicability and reports of efficacy (246). In the tropical population P.618 of India, in which viral hepatitis is the most common cause of FHF, older age, cerebral edema, and degree of prolongation of prothrombin time have been identified as factors indicative of poor prognosis. As already referred to, fulminant presentations (with encephalopathy) of Wilson disease and Budd-Chiari syndrome in association with extensive hepatocellular necrosis are generally considered to represent indications for urgent OLT. Primary myeloproliferative disorders responsible for the Budd-Chiari syndrome should not be considered a contraindication to this intervention (246). The possible prognostic value of circulating and intrahepatic cytokine levels has been the subject of several recent reports. In a report from the United Kingdom, circulating levels of both IL-6 and IL-8, but not TNF-α, were found to be significantly higher in patients who subsequently died than in those who survived (147). Lack of correlation with degree of liver failure, as reflected by prothrombin time, serum bilirubin level, or degree of hepatic encephalopathy, suggested that these parameters reflected not the severity of FHF per se but rather complications such as circulatory disturbance and resultant extrahepatic multiorgan failure. Indeed, the hemodynamic instability of which they are reflective would preclude OLT. A Japanese study found that, at hospital admission, circulating levels of TNF-α and IL-10, but not IL-6, were significantly higher in patients who died than in those who survived. In keeping with the United Kingdom experience, circulating levels of these cytokines did not correlate significantly with the degree of liver injury, as reflected by serum transaminase values (148). A German series found no significant correlations between intrahepatic levels of IL-12, IFN-γ, or IL-10, at either protein or mRNA levels, and jaundice-to-encephalopathy time, encephalopathy grade, requirement for inotrope support, serum bilirubin level, prothrombin time, or APACHE II score (146). As alluded to earlier, hyperphosphatemia, possibly as a consequence of renal impairment and lack of substrate utilization due to blunted hepatic regenerative activity, has recently been reported to be an early predictor of poor outcome in severe acetaminophen-related liver injury (171). In a series of 125 patients, including 30 with hepatic encephalopathy, a threshold phosphate concentration of 1.2 mmol/L or above at 48 to 96 hours after overdose had higher sensitivity, predictive accuracy, and positive predictive values and NPVs for death than the King's College criteria (89% vs. 67%, 98% vs. 92%, 100% vs. 80%, and 98% vs. 93%, respectively). Specificity was 100%. Consideration of the King's College criteria in combination with the phosphate level led to improvement in sensitivity to 94%. As with consideration of blood lactate levels (242), patients with a poor outcome were identified substantially earlier using the phosphate criteria (median 1 hour after referral) than with the King's College guidelines (median 12 hours). Adrenal insufficiency has also recently been shown to correlate with outcome. Patients who did not survive to discharge from the intensive care unit or underwent liver transplantation had significantly lower increment and peak cortisol levels after stimulation with tetracosactide (Synacthen) than those who survived. Higher incidences of subnormal increment and peak cortisol levels were found in nonsurvivors (55%) than in survivors (21%) (175). Nonetheless, the relative lack of both sensitivity and specificity limits the usefulness of these parameters for prognostic modeling.

Trends in Transplantation Activity

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Data from the National Transplant Database of the United Kingdom and Ireland indicate that the number of patients with acetaminophen-induced FHF who were listed for super-urgent OLT increased by more than 75% during the period from 1995 to 1998, accounting for 40% of all super-urgent listings and 38% of all super-urgent transplantations in the 12 months to August 1998. In more recent years, however, the numbers have fallen progressively with the proportion of patients listed and undergoing transplantation in 2001/2002 reducing to 53% and 56% of their 1997/1998 values, respectively. As a corollary, the number of patients listed and undergoing transplantation for FHF of other etiologies has increased, including a more than 50% increase over the last few years in the number of patients listed for acute graft dysfunction after transplantation (247), presumably reflecting a greater use of marginal liver grafts. The number of patients undergoing transplantation for FHF because of non–A to E hepatitis has also increased over this time (247) as a direct consequence of greater organ availability for super-urgent transplantation consequent to the reduction in acetaminophenrelated procedures rather than an increase in the prevalence of FHF due to seronegative hepatitis. Priority listing within the super-urgent category in the United Kingdom and Ireland offers the possibility of ABO-matched grafts being available within 24 to 72 hours. Recent experience from the United States is that 66% of patients with FHF listed for transplantation received a graft after a median waiting time of 3 days and 18% on the waiting list died after a median 5 days. These findings indicate that lack of early donor organ availability remains a crucial factor limiting survival (248). As in the United Kingdom, a relatively low percentage of acetaminophen-related cases compared to those with FHF due to other etiologies underwent transplantation because of the relatively high spontaneous survival rate (248). P.619

Outcome of Transplantation The most recent analysis from the European Liver Transplant Registry (ELTR) (Hôpital Paul Brousse, Villejuif, France) documents 1-, 5-, and 10-year survival rates of 63%, 59%, and 54%, respectively, after cadaveric OLT for FHF. The plateau in mortality rate after the first 3 months reflects the fact that patients undergoing transplantation are critically ill before the procedure and often undergo a complicated early postoperative period. Survival is substantially reduced in patients with sepsis and multiorgan failure before OLT (249). Nonetheless, ELTR data indicate that those patients who survive beyond the first 3 months follow a survival curve comparable to that seen after elective OLT performed for cirrhosis. A center workload of fewer than 25 transplantations per year and fewer than 20 split liver grafts per year were among the risk factors for poor outcome after liver transplantation (250). In the best centers, outcome with split liver grafts is comparable to that after the use of full-size organs (251). An important issue is the potential for viral-related cases of FHF to recur posttransplantation, especially under the influence of immunosuppression. Patients undergoing transplantation for fulminant HBV infection have a significantly reduced rate of hepatitis B recurrence than those undergoing transplantation for HBV-related cirrhosis (252). This presumably relates to the high prevalence of viral clearance before the procedure. Recurrent HBV-related FHF is distinctly uncommon. Graft damage due to recurrent HAV and other viral infections, including those described with Toga-like particles, is occasionally seen after OLT for fulminant disease (253). Although some degree of hepatitis C recurrence is almost universal after OLT for cirrhosis, there are little data in the FHF setting. Recurrence of hepatitis E has not been observed in the small number of patients undergoing transplantation for fulminant HEV infection to date. A retrospective comparison of costs and cost-effectiveness of OLT performed for FHF and cirrhosis was recently reported (254). Costs up to 1 year were estimated to be 107,675 for the cirrhosis cases and 90,792 for those undergoing transplantation for FHF. OLT was considered less cost-effective when performed for FHF than for cirrhosis on account of the lower 1-year post-OLT survival in the former group.

Auxiliary Partial Transplantation The use of auxiliary partial OLT is based on the undoubted potential for spontaneous liver

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regeneration in FHF. This technique involves the removal of the left- or right-lobe segments of the diseased liver and their replacement by the equivalent segments of the donor organ. Right-lobe transplantation is generally used in adults, while a left lobe harvested from an adult graft may suffice for a child. Results published from the European Auxiliary Liver Transplant (EURALT) co-operative Study (255) show a survival rate comparable to that of conventional OLT and that immunosuppressive therapy could be withdrawn, leading to graft atrophy, in 65% of patients surviving at 1 year, in whom adequate regeneration of the native liver had occurred. Similarly, full regeneration of the native liver was documented in 8 of 11 (74%) surviving patients in a series of 17 auxiliary partial OLT recipients from two French centers (256). Immunosuppressive treatment was subsequently withdrawn or the dosage tapered in seven of these eight patients. Differing results have been reported by Azoulay et al. (257), who recently compared auxiliary partial OLT with standard whole-liver transplantation in a consecutive series of 49 patients undergoing transplantation for fulminant or subfulminant hepatitis at another French center. OLT was performed in 37 patients and auxiliary partial OLT in 12. Each patient treated with auxiliary partial OLT was matched to two patients undergoing OLT according to age, coma grade, etiology of liver failure, and clinical course. Although 1-year patient survival was identical (66%) in the two groups, the complication rate was higher in the auxiliary partial OLT recipients. In particular, patients undergoing the auxiliary procedure experienced significantly more technical complications (1 ± 1.3 vs. 0.3 ± 0.5), episodes of bacteremia, requirement for retransplantation (3/12 vs. 0/24), and neurologic sequelae or brain death (4/12 vs. 2/24). Only in 2 of 12 auxiliary partial OLT recipients (17%) was the procedure a complete success, as reflected by the ability to withdraw immunosuppression and patient survival.

Living-Related Transplantation In parts of the world where cadaveric organ donation is not widely accepted, recourse has been made to the living-related donor procedure, especially in children. The 1-year survival rates after living-related OLT for FHF in a total of 35 pediatric cases in three reported series (258,259,260), using left lobe and left lateral segments, ranged from 59% to 90%. Livingrelated left lobe, right lobe, and extended right lobe OLT has also recently been used successfully in cases of adults with FHF. The 1-year survival rate in the largest reported series of 53 adult patients in Japan was 75% (261). Pioneering work in Hong Kong has demonstrated that a graft in excess of 40% of standard liver volume is often required to reverse the severe metabolic derangements that occur in FHF (262,263). This can translate to the requirement for an extended right lobe graft for adult recipients, although P.620 few centers go as far as this. At least some degree of live donor graft injury is common in small-for-size adult recipients. In particular, patients receiving a right lobe graft less than 40% of standard liver weight often develop transient portal hypertension after reperfusion, accompanied by intragraft upregulation of endothelin-1 and ultrastructural evidence of sinusoidal damage (264). Reduction in portal blood flow by portocaval shunting and splenic artery ligation may alleviate this “small-for-size” phenomenon and even allow the use of the left lobe for transplantation (265,266). Low-dose treatment with the NO donor, FK409, has recently been shown to attenuate small-for-size liver graft injury in rats (267). A relatively high rate of biliary complications ranging from 15% to 64% has also been reported with living-related liver transplantation (268). Nonetheless, availability of right lobe living-related transplantation has been shown to substantially improve the survival rate of adults with FHF, with 50% of patients enrolled in such a program surviving compared to only 6% managed medically while awaiting a cadaveric graft in a recent series from Hong Kong (269). Rigorous donor selection criteria, both physical and psychological, along with expert postoperative care are required if the safety of the donor is not to be compromised. The reported incidence of donor death in the United States is in the order of 0.2% overall (270), substantially higher than that for kidney donation, which carries a risk of death in the order of 0.03%. Cases of donor death have also been reported from Asia and Europe. Concern has been expressed about the ability to properly assess potential donors on an emergency basis, as is necessary when dealing with FHF. Although in the pediatric setting parents approach the possibility of living-related liver transplantation with enthusiasm, a recent analysis found that

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almost two thirds of potential donors were ultimately considered unsuitable for organ donation, with both parents deemed unsuitable in over 20% of cases (271). Living-related transplantation from adult to adult is being increasingly performed in the United States and Europe.

Extracorporeal Liver Support An ever-increasing number of extracorporeal devices of varying complexity are being developed as potential alternatives to auxiliary partial OLT for providing temporary liver support in FHF. Approaches to extracorporeal liver support may be broadly categorized as artificial, which contain no biologic component, or bioartificial, which include viable liver cells in culture within bioreactors or involve perfusion of the patient's blood through an isolated human or porcine whole liver.

Artificial Liver Support Early attempts at extracorporeal support based on purely artificial modalities, such as exchange blood transfusion, conventional plasmapheresis, hemodialysis, and hemoperfusion over charcoal or resins (272,273,274,275,276,277,278), were based on the premise that removal of water-soluble and albumin-bound toxins was of paramount importance. The best studied of these artificial modalities is charcoal hemoperfusion. Charcoal is an effective adsorbent for a range of water-soluble molecules in the low-to-middle molecular weight range (up to 5 kDa) and many purported toxins that accumulate in the serum of patients with FHF, such as mercaptans, γ-aminobutyric acid, aromatic amino acids, and fatty acids, but not ammonia (which is heavily ionized at physiologic pH), can be removed or at least reduced in concentration by charcoal hemoperfusion. By contrast, compounds tightly bound to plasma proteins are, in comparison, poorly adsorbed to charcoal (277,278). A number of experimental studies performed in both small and large animal models of FHF reporting a survival benefit with charcoal hemoperfusion, especially with earlier intervention (279,280,281,282), led to initial clinical assessment in patients with FHF and advanced encephalopathy grade (283,284,285). These studies found improved metabolic profiles, including an increased branched-chain amino acid to aromatic amino acid ratio, and at least a transient recovery of consciousness in most treated patients. However, no survival benefit was demonstrated in the only randomized clinical trial performed, even when confounding influences such as etiology of FHF and the jaundice-to-encephalopathy time were taken into account (5). Neither has improved survival in FHF been convincingly demonstrated with any of the other artificial systems listed in the preceding text. Recent interest has centered on the possible value of large-volume plasmapheresis in FHF, with uncontrolled reports mainly of neurologic improvement and significant reduction in arterial ammonia levels (286,287). Two hemodiadsorption systems that variously combine the processes of hemodialysis and adsorption to charcoal, resins, or albumin, namely the BioLogic-DT device and the molecular adsorbent recirculating system (MARS), are also currently undergoing assessment. As compared to charcoal hemoperfusion alone, removal of tightly protein-bound compounds is enhanced by perfusion over resins or albumin, while reduction in ammonia levels is achieved by dialysis or perfusion over resins (288,289,290,291). The BioLogic-DT system utilizes a flat-bed cellulose membrane for hemodialysis against a suspension of powdered charcoal (with surface area substantially greater than that of granules or beads in a column) and cation exchange resin (292). Nonetheless, clearance of solutes is limited to those that are permeable through the cellulose P.621 membrane, such that removal of highly protein-bound compounds including unconjugated bilirubin remains limited (293). Preliminary experience in a small number of patients with acute on chronic liver disease has demonstrated instances of improvement in neurologic status after daily, 6-hour treatments (292), although no substantial impact on either encephalopathy grade or overall survival was demonstrated in the setting of FHF (294).

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▪ Figure 21.3 Schematic representation of exchange of albumin-bound toxin (ABT) from serum albumin of the patient through the molecular adsorbent recirculating system (MARS) membrane to the dialysate albumin. (Reproduced with permission from Mitzner SR, Stange J, Klammt S, et al. Improvement of hepatorenal syndrome with extracorporeal albumin dialysis MARS: results of a prospective, randomized, controlled clinical trial. Liver Transplant 2000;6:277–286.)

The MARS enables albumin-bound toxins to be removed by dialysis, along with other conventionally dialyzable compounds, as a consequence of the use of a double-sided, albumin-impregnated polysulfone or a hollow-fiber dialysis membrane as a molecular adsorbent in a closed-loop dialysis circuit (295) (Figs. 21.3 and 21.4). Such an approach is based on the long-recognized principle that albumin molecules with free binding sites compete for toxins bound to carrier proteins in perfused blood (284). Incorporation of 5% human albumin in the dialysate results in the transfer of adsorbed toxins in turn from the membrane to the dialysate. The dialysate is then perfused over charcoal and resin adsorbents to remove albumin-bound toxins from the P.622 dialysate albumin and finally dialyzed to remove water-soluble toxins, including ammonia, in readiness for the next cycle. Most experience with MARS to date has been obtained in patients with acute on chronic liver disease. A survival benefit has been suggested in small case series (296) and one controlled study (297). Results of a large, multicenter randomized trial under way in the United Kingdom and Europe are awaited. A recent report documents the successful treatment of fulminant Wilson disease with albumin dialysis, which resulted in the removal of substantial quantities of albumin-bound copper and bilirubin and reversal of multiorgan failure before OLT was performed (298). Other successful experiences have been reported, including spontaneous survival without OLT in cases of acetaminophen overdose and bridging to retransplantation in cases of primary nonfunction of a liver graft (299), although, despite all the difficulties, only with a controlled clinical trial will a definite answer about efficacy be obtained.

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▪ Figure 21.4 Schematic diagram of the molecular adsorbent recirculating system (MARS) circuit. (Reproduced with permission from Mitzner SR, Stange J, Klammt S, et al. Improvement of hepatorenal syndrome with extracorporeal albumin dialysis MARS: results of a prospective, randomised, controlled clinical trial. Liver Transplant 2000;6:277–286.)

Table 21.7. Various Bioartificial Liver Devices Designed as Alternatives to the Hepatassist and Extracorporeal Liver Assist Device, for which Preliminary Clinical Experience is Available

Additional Name of

Site of

device

development

detoxification Cell type

components

Comments

TECA Hybrid

Beijing,

1–2 × 10 1 0

Charcoal

Assessed in

Artificial Liver

China

freshly

column

three

Support

isolated

patients with

System

porcine

FHF;

hepatocytes

improvement in neurologic status and blood ammonia levels reported (310)

Bioartificial

Pittsburgh,

70–120 g

Liver Support

United

freshly

Nil

Assessed in two patients

System

States

isolated

with FHF;

porcine

improvement

hepatocytes

in blood

mixed with

ammonia but

20% collagen

not neurologic status

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reported (311)

Radial Flow

Ferrara,

200–230 g

Bioreactor

Italy

freshly

Nil

Assessed in four patients

isolated

with FHF and

porcine

three with

hepatocytes

primary nonfunction; six of seven bridged to OLT; mean reduction in blood ammonia 33% (312)

Hybrid Liver

Berlin,

500–600 g

Support

Germany

freshly

seven

isolated

patients with

porcine

FHF; all

hepatocytes

bridged to

System

Nil

Assessed in

OLT; elevated blood ammonia levels not corrected (313)

Modular

Berlin,

500–600 g

Albumin

Assessed in

Extracorporeal

Germany

freshly

dialysis

two patients

Liver Support

isolated

with FHF;

human

both bridged

hepatocytes

to OLT; improvement in neurologic status in both cases (314)

AMC-

Amsterdam,

1 × 10 1 0

Biaortificial

The

freshly

Nil

Assessed in 12 patients

Liver

Netherlands

isolated

with FHF; 11

porcine

of 12 bridged

hepatocytes

to OLT; 1 patient recovered without OLT; mean reduction in blood ammonia 44% (315)

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Bioartificial

Udine, Italy

1.5 × 10 1 0

Nil

Assessed to

Hepatic

cryopreserved

date in only

Support

porcine

one patient

System

hepatocytes

(with acute on chronic rather than FHF); Neurologic status and blood ammonia levels improved (316)

Hybrid-

Nanjing,

1 × 10 1 0

Charcoal

Assessed in

Bioartificial

China

freshly

column or

12 patients;

isolated

bilirubin

clinical data

porcine

absorption

limited—9

hepatocytes

column or

patients said

plasma

to have

exchange

improved

Liver

(317)

FHF, fulminant hepatic failure; OLT, orthotopic liver transplantation.

An important consideration in assessing liver support strategies is whether the treatment can reduce the elevated plasma levels of proinflammatory cytokines, which, among other influences, are associated with the development of multiorgan failure and a poor prognosis (300,301). In vitro experiments suggest that perfusion P.623 of plasma over resins or charcoal achieves this aim to varying extents, depending on the adsorbent used and the cytokine in question, whereas hemodialysis using either polysulfone or polyacrylonitrile membranes is ineffective (302). Plasma exchange has been shown to reduce plasma concentrations of TNF-α and IL-6 in patients with FHF and primary nonfunction of hepatic grafts (303,304), although this has not always been the reported experience in other disorders associated with increased circulating cytokine levels (305). Treatment with the BioLogic-DT system results in further elevations in plasma levels of TNF-α and IL-8, possibly as a result of activation of peripheral blood mononuclear cells when passing through the extracorporeal circuit (306). A plasma separation system has recently been incorporated into the circuit, and a preliminary report has indicated a reduction in IL-1β levels with its use (307). An additional, although unproven, concern with some artificial systems is that the treatment may remove hepatotropic factors essential for liver regeneration, such as HGF and TGF-α.

Bioartificial Liver Support Several bioartificial liver devices, containing viable hepatocytes as a component with the aim of providing additional synthetic and biotransformatory liver functions but differing substantially in both the hepatocyte component and bioreactor design, are currently being assessed either experimentally or clinically (308,309,310,311,312,313,314,315,316,317) (Table 21.7). The simplest design consists of cartridges containing hollow fiber membranes, with perfusion of the patient's blood or plasma through the hollow fiber lumen and culture of the hepatocyte component in the extrafiber space (Fig. 21.5). Although the additional incorporation of nonparenchymal cells may be advantageous for maintaining hepatocyte viability and function in culture as a result of secretion of extracellular matrix (318,319),

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their inclusion might also have deleterious effects if these cells become activated in culture or during clinical application and produce cytokines such as TGF-β associated with the apoptosis of hepatocytes and inhibition of liver regeneration.

▪ Figure 21.5 Diagram of a hollow fiber cartridge, on which the bioartificial liver (BAL) and extracorporeal liver assist device (ELAD) are based. The close-up view shows cells attached to the external surface of the hollow fibers. (Reproduced with Permission from: Ellis AJ, Sussman NL, Kelly JH, Williams R. Clinical experience with an extracorporeal liver assist device. In: Lee WM, Williams R, eds. Acute liver failure. Cambridge, Cambridge University Press, 1997:255–265.)

Of the devices that have so far undergone preliminary clinical evaluation, most experience is with the “HepatAssist” bioartificial liver support system, which contains porcine hepatocytes as the cellular component, the number approximating 2% of the normal adult hepatocyte mass, and a charcoal column (308) (Fig. 21.6). The hepatocyte component is attached to dextran microcarriers, thereby promoting cell growth and maintenance of cell function in culture (Fig. 21.7). Uncontrolled data suggested more impressive improvement in neurologic rather than metabolic parameters. A prospective, randomized, multicenter controlled trial of the HepatAssist device has recently been completed in the United States and Europe. A significant survival advantage was demonstrated in patients with FHF treated with the device, excluding those with primary graft nonfunction post-transplantation, compared P.624 with controls managed with full medical supportive measures alone (44% reduction in mortality) (308). Although a porcine endogenous retrovirus resistant to lysis by human complement and capable of infecting human cells in vitro has been reported (320), no instances of transmission of this infection on using porcine hepatocytes in the HepatAssist device or others incorporating these cells have yet been documented (321).

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▪ Figure 21.6 Schematic representation of extracorporeal perfusion with the HepatAssist bioartificial liver. (Modified with permission from Rozga J, Podesta L, LePage E, et al. A bioartificial liver to treat severe acute liver failure. Ann Surg 1994;218:538–546.)

▪ Figure 21.7 Attachment of hepatocytes to microcarrier beads is a commonly used technique to promote cell growth and maintain differentiated function in culture (A). Encapsulation of cells within semipermeable microcapsules, such as with alginate– polylysine (B) is an alternative technique. (Modified with permission from Gerlach JC. Hepatocyte culture and bioreactor design for liver support systems. In: Lee WM, Williams R, eds. Acute liver failure. Cambridge, Cambridge University Press, 1997:245–254.)

In the only other controlled experience with a bioartificial liver device so far reported, a pilot but controlled clinical trial of the “extracorporeal liver assist device” (ELAD), which contains a human hepatoblastoma cell line in numbers in the order of 15% of the normal adult hepatocyte mass (309) (Fig. 21.8), demonstrated no statistically significant clinical or metabolic effect in treated patients. Several alternative designs to the HepatAssist and ELAD have been developed and at least preliminarily assessed clinically

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(310,311,312,313,314,315,316,317,322). The design characteristics and preliminary clinical experiences with these devices are summarized in Table 21.7. No controlled data are available. Only one device currently undergoing assessment incorporates scarcely available primary human hepatocytes as the cellular component. The functional capacity and suitability or otherwise of immortalized or reversibly immortalized human hepatocytes (323) for use in bioartificial liver support devices represents another area of important investigation. The use of human, as well as porcine, whole livers for extracorporeal perfusion is also the subject of ongoing interest. Although uncontrolled, metabolic and neurologic improvement was documented in a cohort of 14 patients treated with continuous perfusion until liver transplantation or withdrawal of support. Arterial ammonia levels fell from a median 146 to 83 µmol/L over the first 12 hours, and this reduction persisted for at least 48 hours. Whether pig or human livers were perfused was associated with comparable reductions in P.625 blood ammonia levels. Nine patients were successfully bridged to transplantation (324)

▪ Figure 21.8 Schematic representation of extracorporeal perfusion with the Extracorporeal Liver Assist Device. (Modified with permission from Gislason GT, Lobdell DD, Kelly JH, Sussman NL. A treatment system for implementing an extracorporeal liver assist device. Artif Organs 1994;18:385–389.)

Hepatocyte and Stem Cell Transplantation The feasibility of isolated hepatocyte transplantation as a therapeutic tool has been demonstrated in studies performed in animals with liver-based metabolic defects, such as analbuminemic and Gunn rats, hypercholesterolemic rabbits, and dogs with impaired purine metabolism (325,326,327,328,329). These studies, in which syngeneic or allogeneic primary hepatocytes in quantities ranging from approximately 2% to 15% of the animal's normal liver cell mass were delivered by intraperitoneal, intrasplenic, or intraportal injection, generally demonstrated satisfactory, if incomplete, correction of the metabolic defect for periods, on occasion, of over 150 days. Approximately 50% to 95% of hepatocytes transplanted in this way are incorporated into liver parenchyma after their deposition in hepatic sinusoids, the remainder sequestrating in other sites, including an estimated 2% to 3% in the pulmonary circulation (330,331,332). The latter are rapidly destroyed in pulmonary capillaries, and the clinical relevance of pulmonary translocation has been considered limited (333). Transient respiratory insufficiency was described in a proportion of treated patients in a recent series (334), while other potential complications include portal vein thrombosis and splenic infarction (335). Successful hepatic engraftment of transplanted hepatocytes is associated with a transient five- to sixfold increase in transaminase levels, along with other evidence of

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microcirculatory damage to the host liver (336). The development of portal hypertension precludes the transplantation of larger quantities of hepatocytes, at least as given in one session. Experience with hepatocyte transplantation in experimental animals with FHF due to chemically induced hepatic necrosis or surgical models of hepatic ischemia or resection has generally demonstrated improved survival, even when small numbers of cells, in the order of only 0.5% to 3% of normal hepatocyte mass, are used (322,327,328,329,330,331,332,333,334,335,336,337,338,339,340). Evidence of enhanced regeneration of the native liver has been reported, possibly as a result of reduction in levels of transforming growth factor β (341). However, transplantation was performed before the induction of FHF in some surgical models, a scenario clearly incongruous to the clinical setting. Furthermore, the relevance of animal models in which the liver is removed to the clinical situation of FHF is uncertain. Transplantation of freshly isolated or cryopreserved human hepatocytes has, to date, been performed in only a small number of pediatric and adult patients with FHF (342,343,344,345,346,347,348). Instances of mostly short-term improvement in encephalopathy and some metabolic parameters have been recorded both in OLT and P.626 non-OLT candidates, generally after a lag period of several days, possibly reflecting the time necessary for effective engraftment, as in experimental animals (Table 21.8). No randomized, controlled data are currently available. Light microscopic and fluorescent in situ hybridization evidence of persistence of hepatocytes for up to 52 days post-transplantation has been recorded (334). On the basis of experimental evidence that transplanted allogeneic hepatocytes stimulate a weak humoral but strong cell-mediated host immune response (349,350), systemic immunosuppression has been instituted in the clinical applications so far. Alternative strategies for preventing rejection without the need for immunosuppressive drugs, including the transplantation of encapsulated hepatocytes (351), are currently under investigation in animal models.

Table 21.8. Clinical Experiences with Hepatocyte Transplantation in Fulminant Hepatic Failure in Adults and Children

Transplanted Recipients

N

hepatocytes

Assessment of efficacy

Adults

Bilir et al.

1

(342)

Bilir et al.

6

(343)

1 × 10 9 cryopreserved

Improvement in encephalopathy

human hepatocytes

and reduction in prothrombin time;

delivered by injection

subsequent deterioration

into splenic artery

precipitated by sepsis

Cryopreserved human

One patient withdrawn because of

hepatocytes (number

anaphylactoid reaction; of the

not stated) delivered

remaining five patients, three

by percutaneous

(60%) survived >72 h (12–52 d),

injection

with transient improvement in encephalopathy, blood ammonia levels, and prothrombin times (no patient was considered an OLT candidate)

Bilir et al. (344)

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1

3 × 10 1 0 cryopreserved

No clinical benefit observed and

human hepatocytes

patient died within 18 h.

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delivered through transjugular intraportal injection

Habibullah

6

et al. (345)

6 × 10 7 ABO-matched

Blood ammonia level reduced in

fetal hepatocytes per

80% of those in whom serial levels

kilogram body weight

available; survival rate 30%

delivered by

compared with 33% in patients not

intraperitoneal injection

consenting to hepatocyte transplantation; OLT not available

Strom et al.

2

(346)

3 × 10 7 to 2 × 10 8

Each patient with grade III or IV

ABO-matched human

hepatic encephalopathy at time of

hepatocytes (depending

transplantation; reduction in blood

on availability; ≤0.1%

ammonia level in both patients,

adult hepatocyte

who underwent OLT after 3 and 10

mass); cryopreserved

d; none of three patients for whom

hepatocytes used in

no hepatocytes were available for

one case, freshly

transplantation survived for >3 d

isolated cells in the other; cells delivered by injection into splenic artery

Strom et al.

5

(347)

Human hepatocytes

Four patients with grade III or IV

delivered by injection

hepatic encephalopathy at time of

into splenic artery as in

transplantation; three bridged to

the preceding entry

OLT 1–5 d later; one died on day 5 before OLT could be performed; the other patient, with grade I hepatic encephalopathy before hepatocyte transplantation, survived without OLT

Children

Strom et al.

ABO-matched human

Five children with grade IV hepatic

(346,347),

6

hepatocytes delivered

encephalopathy at time of

Soriano et

by injection into splenic

hepatocyte transplantation; four of

al. (348)

artery

these patients (80%) died within 7 d, despite instances of reduction in serum ammonia levels and requirement for inotropicx support; one of these children recovered without OLT, having received multiple infusions of hepatocytes over a 3-d period; the other child, with grade I hepatic encephalopathy at the time of hepatocyte transplantation, underwent OLT 2 d after the procedure

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OLT, orthotopic liver transplantation.

The limited availability of primary human hepatocytes for transplantation represents a major difficulty. Isolation of hepatocytes from livers rejected for liver transplantation is the standard approach, with reported yields in the order of 7 million cells per gram of digested tissue and a mean cell viability of 73% (352). With the source of such hepatocytes in increasingly short supply, the feasibility of harvesting tumor-free hepatocytes from macroscopically normal liver unavoidably removed during hepatic resection for malignancy has recently been demonstrated using an immunomagnetic filtration technique (353). In addition to the potential P.627 new sources of primary human hepatocytes, recent data suggesting that cell viability and function after cryopreservation can be substantially improved with the use of University of Wisconsin solution as a cryopreservation medium (354,355) may enhance the future applicability of hepatocyte transplantation in the FHF setting. Transplantation of hepatocytes with fibrin or other biomatrix, shown in both mice and pigs to result in enhanced hepatocyte engraftment and in maintaining differentiated cell function (356,357), is another technical advance yet to be clinically trialled. The possible benefit to hepatocyte survival of cotransplantation with nonparenchymal cells, as suggested in rats (358), also remains to be established clinically. In experimental models, repopulation of the whole liver can be obtained with infusion of relatively small numbers of purified hepatic stem cells that are able to replicate at least 100 times without loss of function or malignant transformation, as identified in adult rodent liver (359,360). Repopulation experiments using purified fractions of total liver cell suspensions will be required to identify any such cells in the adult human liver (361). Of note, a bone marrow–derived stem cell capable of repopulating the liver with mature hepatocytes after hepatic injury has recently been described in rodents. In the order of 1.0 × 10 6 hepatocytes (approximately 0.1% of the total hepatocyte mass) originated from transplanted bone marrow cells by day 13 after liver injury (362). If extrapolated from the animal to the human situation, the time required for engraftment and cell differentiation would be problematic in the acute setting. On the premise that the fetal liver contains epithelial cells that are in different stages of lineage progression, some of which may exhibit the full regenerative potential of stem cells, transplantation of fetal hepatocytes, rather than the use of adult cells, has been suggested (347). Clinical data so far are limited, and the range of ethical issues pertaining to the use of fetal cells is currently the subject of much debate. As with approaches to providing extracorporeal support, controlled trials on a multicenter basis in well-defined patient groups and with standardized outcome measures will be essential to properly evaluate the clinical value of hepatocyte transplantation in FHF. A better understanding of mechanisms responsible for the development of liver cell death and complicating multiorgan failure, along with strategies to enhance liver regeneration, may in future enable a more targeted approach to extracorporeal and cell-based therapies for this disorder.

Annotated References

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Blei AT. The pathophysiology of brain edema in acute liver failure. Neurochem Int 2005;47:71–77. An overview of current concepts about the pathophysiology of intracranial hypertension in fulminant hepatic failure. Jalan R, Olde Damink SWM, Deutz NEP, Hayes PC, Lee A. Moderate hypothermia in patients with acute liver failure and uncontrolled intracranial hypertension. Gastroenterolgy 2004;127:1338–1346. Documents ongoing experience of beneficial effects of lowering of the core body temperature on systemic and cerebral haemodynamics in patients with fulminant hepatic failure. O’Grady JG, Schalm S, Williams R. Acute liver failure: redefining the syndromes. Lancet 1993;342:373–375. An important paper that describes a classification system for fulminant hepatic failure with prognostic implications. Riordan SM, Williams R. Mechanisms of hepatocyte injury, multiorgan failure and prognostic criteria in acute liver failure. Semin Liver Dis 2003;23:203–215. An overview of molecular mechanisms of hepatocellular damage that underlie the development of fulminant hepatic failure. van de Kerkhove MP, Hoekstra R, Chamuleau RA, van Gulik TM. Clinical application of bioartificial liver support systems. Arch Surg 2004;240:216–230. An overview of reported experiences with various bioartificial liver support systems for which preliminary clinical data are currently available.

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Editors: Title:



Copyright ©2007 Lippincott Williams & Wilkins > Table of Contents > Volume I > Section IV - Cholestatic Disorders > Chapter 22 Gallstone Disease: Pathogenesis and Treatment

Chapter 22 Gallstone Disease: Pathogenesis and Treatment Joanne M. Donovan Fred M. Konikoff

Key Concepts z

Gallstones affect approximately 10% of the population in the western world. Common risk factors for stones include age, female sex, obesity, pregnancy, ethnic origin (i.e., American Indian > European > African and Asian), rapid weight loss, chronic hemolytic states, and cirrhosis.

z

Gallstones are divided into three types on the basis of their composition. Cholesterol gallstone formation involves hepatic cholesterol hypersecretion, gallbladder hypomotility, mucin hypersecretion, and intestinal metabolism of bile salts. Black pigment gallstone formation is associated with hypersecretion of conjugated bilirubin, which undergoes conversion to the insoluble unconjugated form, which then precipitates as the calcium salt. Brown pigment stones form within the bile ducts as a consequence of biliary stasis and infection, causing degradation and precipitation of biliary components.

z

Most gallbladder stones are asymptomatic and do not require treatment. Stones most often present with biliary colic before the development of complications that include acute cholecystitis, biliary obstruction, or pancreatitis. The natural history of bile duct stones is less clear, but because of potentially severe consequences, choledocholithiasis is usually treated, even when asymptomatic.

z

Laparoscopic cholecystectomy is the mainstay of treatment of gallbladder stones. Endoscopic therapy is an important tool for common bile duct (CBD) stones, either in addition to surgery or instead of surgery in high-risk patients.

Gallstone disease is one of the most common gastrointestinal afflictions, affecting 10% or more of the population in western countries. Although stones are most often silent, once symptomatic, their management is a major cause of morbidity, with some mortality and major costs to the health care system (1,2,3,4,5,6). Gallstones are divided into three types on the basis of their composition: Cholesterol, black pigment, and brown pigment. Normally, bile functions as a detergent, facilitating hepatic excretion of otherwise insoluble compounds, as well as intestinal absorption of dietary lipids. Distinct pathophysiologic

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mechanisms lead to incomplete solubilization of biliary components such as cholesterol and unconjugated bilirubin (UCB), with formation of either cholesterol or black pigment stones within the gallbladder (Fig. 22.1). Cholesterol stones constitute approximately 80% of stones in patients in western countries and may be composed of almost pure crystalline cholesterol, with minor amounts of UCB, calcium phosphate, mucin, and proteins. The predominant element of black pigment stones is polymerized calcium bilirubinate, with minor quantities of calcium. Their calcium content renders black pigment stones relatively radiopaque on plain radiographs in contrast to cholesterol stones. In addition to the precipitation of these constituents within the gallbladder, pathophysiologic mechanisms in the liver and intestine contribute to cholesterol and black pigment stone formation. In P.640 contrast, brown pigment stones form when bile duct obstruction and bile stasis lead to bacterial infection and degradation of biliary lipids to insoluble compounds, including calcium bilirubinate, along with cholesterol and calcium salts of fatty acids. Epidemiologic risk factors differ for each type of stone and are discussed in the context of their pathophysiology.

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▪ Figure 22.1 A: Cholesterol stone fractured to show interior structure. Note that individual cholesterol monohydrate crystals can be seen radiating from a pigmented core. B: Black pigment stone composed of polymerized calcium bilirubinate. C: Microscopic view of cholesterol monohydrate crystals from human bile. D: Microscopic view of calcium bilirubinate granules from human bile.

Pathophysiology of Gallstone Formation Biliary Lipid Secretion The principal physiologic functions of bile, absorption of lipids and facilitation of excretion of relatively insoluble compounds, are mediated through the synthesis and secretion of lipid molecules that are either detergents or can cooperatively facilitate solubilization. Major components of bile include bile salts, phosphatidylcholine, and cholesterol, the chemical structures of which are shown in Figure 22.2. (7).

Components of bile Although bile salts are derived from cholesterol, they are quite water soluble, as compared to the insolubility of cholesterol (approximately 10 - 7 mol/L) (8). The chemical transformation from the parent molecule includes truncation of the hydrocarbon side chain with addition of a carboxylic acid and either two P.641

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or three hydroxyl groups. The orientation of the hydroxyl groups allows interaction of the molecule with an air–water or oil–water interface, such that the hydrophilic hydroxyl groups and carboxylic acid can interact with water while the hydrophobic sterol nucleus remains protected from interaction with water. At concentrations above a critical value, denoted by the critical micellar concentration, bile salts self-aggregate to form micelles, with their hydrophobic surfaces on the interior to allow solubilization of otherwise insoluble molecules such as cholesterol (8). Approximately two thirds of secreted bile salts are conjugated with glycine and the other one third with taurine. Conjugation renders bile salts resistant to precipitation at physiologic pH values: Free bile salts precipitate at a pH value less than 7, whereas glycine conjugates precipitate at pH values less than 4.5 and taurine conjugates only below a pH value of 1. Therefore, conjugated bile salts, but not unconjugated bile salts, remain active as detergents throughout the intestine.

▪ Figure 22.2 Chemical structures of typical biliary lipids. Phosphatidylcholine (lecithin) has varying chain lengths, the most common of which is the 1-palmitoyl, 2-oleyl shown here. Cholic acid and chenodeoxycholic acid are the predominant bile salts synthesized by the liver and are secreted as the glycine or taurine conjugate of the carboxylic acid side chain. Cholesterol is secreted as such and contributes the steroid nucleus for bile salt synthesis. Deoxycholic acid is derived from dehydroxylation of cholic acid by intestinal microflora. Ursodeoxycholic acid differs from chenodeoxycholic acid only in the orientation of the hydroxyl group in the seventh position.

Phosphatidylcholine and cholesterol are insoluble membrane components. Both are amphipathic—phosphatidylcholine with a hydrophilic zwitterionic choline head group and hydrophobic acyl chains and cholesterol with a single hydrophilic hydroxyl group and a hydrophobic sterol nucleus. Bile salts interact with phosphatidylcholine and cholesterol to form spontaneous lipid aggregates, micelles, or vesicles (8). Formation of bile salts into simple micelles enhances the

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solubility of cholesterol by approximately 10,000-fold, whereas in the presence of phosphatidylcholine, bile salts form mixed micelles that increase cholesterol solubility by an additional severalfold (9). Exceeding the micellar solubility of cholesterol triggers the formation of unilamellar vesicles composed of a single bilayer of phosphatidylcholine and cholesterol with minor amounts of bile salts (10). Unilamellar vesicles aggregate, fuse, and transform to multilamellar vesicles containing multiple concentric bilayers that can spawn cholesterol crystals (11). Bile salt synthesis is a highly regulated process that occurs principally in the liver (12,13). Distinct pathways are initiated by hydroxylation at either the 7- or 27position, mediated by cholesterol 7α-hydroxylase (Cyp7A1) or sterol-27hydroxylase (Cyp27), respectively (Fig. 22.2). The “classical” pathway of bile acid synthesis is initiated through Cyp7A1 and leads to cholic acid after further hydroxylation at the 12th position. Whereas Cyp7A1 is expressed only in the liver, Cyp27 is expressed widely, including the vascular endothelium. The “alternative” pathway of bile acid synthesis initated by Cyp27 leads to chenodeoxycholic acid, after further 7-hydroxylation by oxysterol-7α-hydroxylase (Cyp7B1) (14). The trihydroxy bile P.642 salt cholate and the dihydroxy bile salt chenodeoxycholate are termed primary bile salts. The deoxycholates, ursodeoxycholates, and the monohydroxy lithocholates (with only the 3-hydroxyl group) are the products of intestinal bacterial transformation of primary bile salts: 12-dehydroxylation of cholate, epimerization of the 7-hydroxyl group of chenodeoxycholate, and 7dehydroxylation of chenodeoxycholate, respectively. The deoxycholates are more powerful detergents and, as discussed later, can play a role in the pathogenesis of cholesterol gallstones (15). Ursodeoxycholate differs from chenodeoxycholate only in the orientation of a single hydroxyl group but does not solubilize cholesterol as well (16). After resorption of more than 95% of bile acids in the ileum by the apical sodium-dependent bile acid transporter (SLC10A2), bile acids are efficiently taken up at the hepatocyte basolateral membrane by the sodiumtaurocholate cotransporting polypeptide (NTCP, SLC10A1) (17) and by multiple sodium-independent multispecific organic anion transporters (OATP-A and OATPC; SLC21A3 and SLC 21A6, respectively) (17). Enterohepatic circulation of bile acids allows efficient conservation of the bile acid pool.

Bile secretion The sterol nucleus of cholesterol can be excreted only as free cholesterol or after transformation to bile acids. The free cholesterol pool is a major determinant of biliary cholesterol saturation. Cholesterol is stored within the hepatocyte either in intracellular membranes, principally the endoplasmic reticulum, or as cholesteryl esters after esterification by acyl cholesterol acyltransferase-2 (ACAT-2) (18). Cholesterol, free and esterified, enters the hepatocyte through lipoprotein uptake in the form of low-density lipoprotein (LDL), high-density lipoprotein (HDL), or chylomicrons carrying dietary cholesterol. Each process is mediated by apical membrane receptors: The LDL receptor (LDLR) and the LDL-related protein (LRP) receptor for LDL and chylomicrons, and scavenger receptor B type 1 (SR-B1) for HDL. Esterified cholesterol can be stored, hydrolyzed by cholesterol esterases, or exported as newly synthesized very low density lipoprotein (VLDL). Newly synthesized cholesterol can be transformed into bile salts, although the major source of cholesterol for bile salt synthesis is HDL cholesterol, as evidenced by impaired biliary cholesterol excretion in mice with decreased levels of SR-B1

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(19). Biliary lipid secretion occurs through the coordinated expression of multiple transporters at the canalicular membrane (17,20). Unconjugated bile salt secretion occurs predominantly through the bile salt export protein (Bsep, ABCB11), a member of the adenosine triphosphate–binding cassette superfamily (21), whereas glucuronidated and sulfated bile salts are excreted by the canalicular multispecific organic anion transporter multidrug resistance protein (MRP2) (22). Phosphatidylcholine is transported from the inner to the outer canalicular membrane by a transmembrane transferase, or flippase, encoded by the murine gene product mdr2 and the human gene product MDR3 (ABCB4), the absence of which is associated with almost total ablation of phosphatidylcholine and cholesterol secretion in bile (23). Cholesterol transport at the canalicular membrane is mediated by two gene products (ABCG5 and ABCG8), which form a heterodimer transport protein (24). However, residual cholesterol excretion is observed in patients with sitosterolemia, in whom both gene products are defective (25); this suggests that cholesterol excretion into bile may occur by alternative mechanisms such as spontaneous transmembrane movement (“flipflop”) (26). Multiple monogenetic defects in canalicular transporter genes, as well as those of the enzymes of bile acid biosynthesis, have been identified with phenotypes ranging from cholesterol gallstone disease to severe early childhood cholestasis (27). Once in the canalicular lumen, bile salts initiate vesiculation of phosphatidylcholine and cholesterol, culminating in the release of unilamellar vesicles (28). Despite the presence of other phospholipids in the canalicular membrane, phosphatidylcholine is virtually the sole phospholipid secreted in bile, consistent with the higher affinity of bile salts for phosphatidylcholine as compared with sphingomyelin (29). The mechanism for the selectivity for phosphatidylcholine versus sphingomyelin is likely to be physicochemical in part, given the greater susceptibility of phosphatidylcholine to bile salt solubilization (29,30). As bile is concentrated, bile salt concentration increases above the critical micellar concentration and solubilizes phosphatidylcholine and cholesterol as mixed micelles (31). The cholesterol content of bile in part depends on the detergent capability of the bile salt species present. More highly detergent hydrophobic bile salts more effectively extract cholesterol from the canalicular membrane to produce bile with relatively higher cholesterol content (32). The relative cholesterol content of bile is most often expressed as the cholesterol saturation index (CSI), which is the amount of cholesterol present divided by the maximum micellar solubility of cholesterol by the bile salts and phosphatidylcholine present. This can be expressed on a ternary phase diagram showing the relative quantities of bile salts, phosphatidylcholine, and cholesterol, where the apices of the triangle represent systems with 100% of each component in aqueous solution or suspension (9). The concentration of cholesterol in human bile fluctuates around the limit of cholesterol solubilization (Fig. 22.3). At lower bile salt secretion rates, such as during fasting when less bile salts are being returned in P.643 the portal circulation, the relative cholesterol content increases (33). Patients with gallstones have somewhat higher CSI values; however, there is great overlap in the distribution of CSI values in bile between healthy individuals and patients with cholesterol gallstones (34).

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▪ Figure 22.3 Cholesterol saturation in bile typically fluctuates around a value of unity for the cholesterol saturation index (CSI). Below a CSI of 1, cholesterol is solubilized in simple and mixed micelles, whereas above a CSI of 1, unilamellar and, ultimately, multilamellar vesicles are formed, from which cholesterol crystallization can occur. (Adapted from Donovan JM. Pathogenesis of gallstones. In: Feldman M, LaRusso NF, eds. Gastroenterology and hepatology: The comprehensive visual reference, vol 6, gallbladder and bile ducts. St. Louis: Mosby, 1997:7.1–7.22.)

Bile acid and cholesterol homeostasis is tightly regulated. The liver X receptor (LXR), which forms heterodimers with the retinoid X receptor (RXR), appears to be the major mediator of cholesterol homeostasis (35). The major ligands of LXR are oxysterols; activation by elevated levels of intracellular cholesterol stores triggers coordinated changes that serve to decrease body cholesterol stores. Among the target enzymes whose activity is enhanced are Cyp7A1 effecting conversion of cholesterol to bile acids, ABCG5/ABCG8 effecting biliary cholesterol excretion, and ABCA1 serving to decrease intestinal cholesterol absorption (36) while downregulating the ileal bile acid transporter to enhance bile acid excretion (35). Similarly, the farnesoid X receptor (FXR), which also forms RXR heterodimers, acts as the major mediator of bile salt homeostasis. The major ligands of FXR are the hydrophobic bile acids, particularly chenodeoxycholate. Elevated intrahepatocyte bile acid levels trigger several homeostatic mechanisms: Cyp7A1 is downregulated, decreasing bile acid synthesis; whereas ABCB4 and ABCB11 are upregulated, increasing phosphatidylcholine and bile acid excretion at the canalicular membrane. The critical importance of FXR is illustrated by the observations that FXR-null mice display a phenotype of cholesterolsupersaturated bile, whereas treatment with an FXR agonist prevents the development of cholesterol gallstones (37).

Cholesterol Gallstones

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Overview of factors in cholesterol gallstone pathogenesis Although cholesterol supersaturation is absolutely required for cholesterol stone formation, multiple factors interact during the formation of stones. As discussed later, cholesterol supersaturation of bile also depresses gallbladder motility. Consequently, the impaired storage capacity of the gallbladder allows a larger fraction of newly secreted bile to be directed to the intestine, where bile salts undergo bacterial transformation to more hydrophobic bile salts such as deoxycholate and lithocholates. Enterohepatic recycling of deoxycholic acid and more efficient extraction of cholesterol at the canalicular membrane can lead to more cholesterol-supersaturated bile. Moreover, cholesterol-supersaturated bile triggers mucin hypersecretion, which accelerates cholesterol crystal P.644 formation and forms a mucous gel layer that impairs biliary clearance of cholesterol crystals and incipient stones (38). Additional factors, such as proand antinucleating substances and possibly bacteria, are also thought to play a role in the processes leading to cholesterol crystallization and gallstone formation.

Cholesterol crystallization When bile is supersaturated with cholesterol, dissolution of vesicles to micelles is incomplete (Fig. 22.4). The remaining vesicles become highly enriched with cholesterol, reaching cholesterol to phosphatidylcholine ratios of 2 or more, which are thermodynamically unstable and cause fusion to produce multilamellar vesicles (10). The similarity of the molecular arrangement of cholesterol in bilayers with that of the crystal structure of cholesterol monohydrate suggests that multilamellar vesicles are crucial in spawning cholesterol crystal formation, as has been observed microscopically (39). Cholesterol exists in gallstones as the thermodynamically favored cholesterol monohydrate form (40). These are rhomboid, platelike microcrystals that aggregate to form the macroscopic stones (41). Under conditions when the driving force for cholesterol nucleation is high, initial crystallization can also occur in other crystal forms, including cholesterol filaments, helices, and ribbons (42). Some of the earliest crystal forms are intermediate polymorphs of cholesterol monohydrate, with a shift in the water molecules in relation to the cholesterol (43,44). As crystallization proceeds, these structures disappear in favor of the more stable cholesterol monohydrate crystals (45).

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▪ Figure 22.4 Cholesterol is secreted in the form of cholesterol/phosphatidylcholine vesicles that are unsaturated with cholesterol in the proximal biliary tree. As bile becomes more concentrated distally, bile salt concentrations rise, causing preferential extraction of phosphatidylcholine from unilamellar vesicles. Consequently, cholesterolenriched vesicles are formed that are thermodynamically unstable. In the gallbladder, vesicles aggregate and fuse and ultimately spawn crystalline cholesterol. (Adapted from Donovan JM. Physical and metabolic factors in gallstone pathogenesis. Gastroenterol Clin North Am 1999;28:75–98.)

The rate of cholesterol crystal formation is higher in bile from patients with cholesterol gallstones than in bile from healthy controls (46). When determined in vitro, cholesterol crystals form within a few days when bile from patients with cholesterol gallstones are incubated at 37°C but may not form in several weeks in bile from control patients. Numerous pronucleating and antinucleating proteins have been identified (47). Proteins that promote nucleation include mucin, fibronectin, α 1 -glycoprotein, N-aminopeptidase, haptoglobin, and immunoglobulins, whereas antinucleating proteins include apolipoproteins A-I and A-II and certain immunoglobulins. The consensus view is that differences in concentrations of these proteins do not distinguish a subgroup of patients destined to develop gallstones (48). The exception may be the pronucleating agent mucin, which plays a crucial role in inhibiting cholesterol crystal clearance from the gallbladder and in internally scaffolding mature cholesterol gallstones (49). Additionally, the process of cholesterol crystal formation can be accelerated by increased cholesterol content, total lipid concentration, and relative bile salt content and hydrophobicity (1).

Role of the gallbladder Gallbladder motor function and mucosal function play critical roles in the formation of gallstones (38,50). Gallbladder filling is a dynamic process characterized by interdigestive partial contractions allowing significant turnover

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of bile during its residence in the gallbladder (51). Impaired gallbladder contractility in patients with cholesterol gallstones prevents complete clearance of nascent crystals, presumably facilitating their P.645 growth to mature gallstones (52). The increased cholesterol content of bile alters the cholesterol content of the sarcolemmal membrane and impairs contractility (53). Hypersecretion of mucin, a heavily glycosylated protein that binds hydrophobic biliary lipids and accelerates cholesterol crystal formation (49), is a central event in both cholesterol and black pigment gallstone formation that can be inhibited by prostaglandin inhibitors (54). Further, this highly viscous gel entraps cholesterol crystals and is a component of biliary sludge (55). The biochemical composition (i.e., lipids, proteins, and bilirubin) of bile is also modified during residence in the gallbladder, contributing to sludge formation (50). The process by which cholesterol gallstones grow is not well characterized but presumably involves both accretion of cholesterol monohydrate crystals and, to a lesser degree, the enlargement of existing crystals (56). Cross-sections of cholesterol stones show a radial arrangement of cholesterol monohydrate crystals, cemented together by a mucin matrix. Frequently, cholesterol stones have pigmented rings, containing small amounts of calcium bilirubinate (57), possibly caused by fluctuations in bile composition during stone formation. In general, stones from a single gallbladder are of a single type (cholesterol or black pigment), with similar compositions. However, a single gallbladder can contain a single large stone or dozens of tiny stones, possibly through different mechanisms (58).

Role of intestinal transit Bacteria may influence gallstone formation not only directly in bile but also indirectly within the intestines (59). Intestinal bacteria can increase deoxycholate production in the gut. Elevated levels of deoxycholate are associated with cholesterol gallstone formation (60). This hydrophobic bile acid has been shown to increase biliary cholesterol secretion, and thereby cholesterol saturation and bile lithogenicity. The observation that cholesterol gallstones are prevalent in patients with acromegaly treated with octreotide led to a series of studies demonstrating that these patients have impaired gallbladder contractility and prolonged intestinal transit times, with increased intestinal production of deoxycholate and increased relative amounts of biliary deoxycholate and cholesterol (61,62). The central mediator appears to be increased conversion of the primary bile salt cholate to the secondary bile salt deoxycholate. Enhanced enterohepatic circulation of deoxycholate leads to cholesterol hypersecretion because deoxycholate is a more potent detergent at the canalicular membrane. Additionally, increased biliary deoxycholate levels accelerate cholesterol crystal formation (63). Further, interventions that increase intestinal transit time also trigger cholesterol stone formation in animal models, a process that can be prevented by agents that enhance intestinal transit (64). Although not all patients with cholesterol gallstones have elevations in biliary deoxycholate levels (65), it is likely that prolonged intestinal transit time and increased deoxycholate levels together are contributing factors in a subgroup of patients without other obvious risk factors (66). Patients with gallstones have been shown to harbor an increased mass of bacteria (mainly Clostridium spp) capable of 7αdehydroxylation and deoxycholate production (61). Moreover, antibacterial

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treatment has been shown to decrease biliary deoxycholate concentration and bile lithogenicity (67)

Genetics A genetic component of gallstones was initially suggested by a host of epidemiologic data (68). In particular, the strikingly high prevalence of gallstones in specific populations such as American Indians strongly supports a genetic background of gallstone disease (69). This clustering of gallstones does not necessarily prove the genetic basis of the disease but could also reflect environmental factors. However, additional data from family studies with spouses, as well as mono- and dizygotic twins, have provided more firm evidence that gallstone formation is indeed genetically determined (70,71). In this background, a series of studies in the mouse model have looked for underlying genetic defects leading to gallstone formation. By using the genetic tool of Quantitative Trait Locus (QTL) analysis with inbred mice, a number of gallstone susceptibility genes, have been identified, which they have termed Lith genes (72,73). To date 16 Lith gene candidates have been identified on 12 different mouse chromosomes, among which several seem to be of greatest potential relevance to cholesterol gallstone formation: Lith 1 on chromosome 2, Lith 2 on chromosome 19, and Lith 9 on chromosome 17. Likely candidate genes include ABCB11 (encoding for the bile salt export pump), ABCC1 (an organic anion transporter), ABCG5/G8 (the cholesterol transporter), and FXR (modulating bile acid metabolism), respectively (74). Absolute confirmation of the relevance of these findings, however, requires verification by experiments with knockout and knock-in animals (75). Epidemiologic studies in humans have revealed several genetic associations with gallstone disease. The ApoE4 genotype has been shown to predispose to gallstone formation in some studies, but not in others (76,77). Patients with progressive familial intrahepatic cholestasis (PFIC) type 3 have defects in ABCB4, which encodes for the phophatidylcholine flippase (ABCB4) (78). Consequent decreases in the phosphatidylcholine to cholesterol ratio in bile result P.646 in decreased cholesterol solubility and accelerated cholesterol crystallization (79). Patients with benign recurrent intrahepatic cholestasis (BRIC) type 2 have mutations in ABCB11, the main canalicular bile salt transporter (80). However, the phenotype of mice strains susceptible to cholesterol gallstone formation has been reported to be that of increased activity of the bile acid transporter with cholesterol gallstone formation (81); hence, it is unclear in humans whether this mutation is associated with gain or loss of function. Patients having defects in the rate limiting enzyme of bile acid synthesis (CYP7A1) have hypercholesterolemia and gallstones and evidence of disproportionate bile acid synthesis through the alternative pathway (82). Observed increases in hepatic cholesterol content and the chenodeoxycholic acid to cholic acid ratio could lead to cholesterolsupersaturated bile, the former by enhancing cholesterol secretion and the latter by augmenting cholesterol solubilization from the canalicular membrane by the more hydrophobic bile acid chenodeoxycholate. Polymorphisms in the promoter region of the gene for the cholecystokinin (CCK) receptor have been identified in patients with gallstones (83). Presumably, impaired gallbladder contractility could increase the risk for gallstones. In general, genetic mutations associated with gallstones tend to present as cholelithasis at a young age.

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Bacteria and gallstones Although traditionally bacteria were not believed to be involved in the pathogenesis of cholesterol gallstones as opposed to brown pigment stones, this concept has been challenged in recent years. Using molecular biology techniques, bacterial deoxyribonucleic acid (DNA) can be found in most cholesterol gallstones (84). Bacteria may form a biofilm that serves as a matrix for crystals and stones (85). They can influence bile lithogenicity by phospholipase activity or the production of mucin, prostaglandins, or oxysterols (86). Recently, several Helicobacter species have been found in the intestines, bile, and even gallstones of laboratory animals and humans (87,88). Moreover, pathogen-free C57L mice failed to develop gallstones on a lithogenic diet (88) Although mounting data suggest that gallstone formation may be significantly influenced by bacteria and bacterial products, the exact role of bacteria in cholesterol gallstone pathogenesis still remains to be determined.

▪ Figure 22.5 Prevalence of gallstones in the US population as determined by ultrasonography. With increasing age, gallstone prevalence increases, and in each age-group, women more commonly have gallstones than men. Mexican Americans have a higher prevalence than non-Hispanic whites or non-Hispanic African Americans. (Data from Everhart JE, Khare M, Hill M, et al. Prevalence and ethnic differences in gallbladder disease in the United States. Gastroenterology 1999;117:632–639.)

Epidemiology and clinical risk factors Clinical risk factors for cholesterol gallstones are most often associated with biliary hypersecretion of cholesterol. Large epidemiologic surveys performed in countries where cholesterol stones are most prevalent have demonstrated that gallstones are common and most frequent in women and occur with increasing frequency at older ages (89,90). Results are similar in studies using abdominal ultrasonography as a screening tool to identify both asymptomatic and symptomatic stones and in studies examining the prevalence of previously diagnosed gallstone disease. The prevalence of gallstones increases with age (Fig. 22.5), apparently as a result of a decrease in bile salt synthesis, leading to an increase in biliary cholesterol saturation (91).

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The propensity for the development of gallstones varies widely among populations (92). The highest prevalence is found among populations of American Indian ancestry, such as the Pima Indians, but extending to North and South American populations with significant genetic contributions from American Indian populations (93). Northern Europeans have a higher prevalence of stones than southern Europeans (5), whereas gallstones are less common among populations of Asian and African ancestry (90). Ancestral P.647 exposure to adverse climates with selection for efficiency of nutrient use has been suggested as a common factor (94). An increased risk occurs within kindreds but does not appear to be mediated by a single gene in most patients. Both endogenous and exogenous estrogens are associated with increases in gallstone prevalence. At every age, women are more likely than men to harbor stones, with the greatest excess prevalence occurring in the premenopausal years when estrogen levels are highest in women (90). Oral contraceptives (95) and estrogen replacement therapy (96) are associated with modest increases (relative risk 25 mm in diameter), it may cause intestinal obstruction, in particular, at the level of the ileocecal valve. Gastric outlet obstruction due to a gallstone impacted in the distal stomach or duodenum is known as Bouveret's syndrome (180).

Diagnostic Modalities in Gallstone Disease Imaging studies can reliably diagnose the presence and location of gallstones. Because gallstones are common in an older population, it is crucial for the clinician to decide whether abdominal symptoms are referable to the biliary tract before performing diagnostic studies. Otherwise, the incidental discovery of gallstones can lead to unnecessary intervention that is unlikely to relieve symptoms. A plain abdominal radiograph rarely detects gallstones because most stones are radiolucent: Less than 25% contain enough calcium to be detected by radiographs. Only on rare occasions of air in the biliary tree (caused by surgery, endoscopic sphincterotomy, or spontaneous biliary enteric fistulation) can the plain abdominal radiograph be of assistance to the clinician. Ultrasonography, on the other hand, has become the primary imaging modality in gallstone disease (Fig. 22.8). It is widely available, inexpensive, and completely noninvasive. Most gallstones these days are detected by ultrasonography, often as an incidental finding when evaluating the patient for an unrelated condition. Abdominal gas and obesity are limiting factors for the use of ultrasonography. Although operator dependent, the accuracy for detecting gallbladder stones, which appear as mobile echogenic foci casting an acoustic shadow, is in general more than 90%. The sensitivity of detecting stones larger than 2 mm in diameter exceeds 95%, with a specificity on the same order of magnitude (181). Ultrasonography can also detect sludge in the gallbladder. A sonographic Murphy's sign P.652 (gallbladder tenderness under transducer pressure) is of value in diagnosing acute cholecystitis. Pericholecystic fluid is an additional quite specific indicator of this diagnosis. Despite its significant use in detecting gallbladder stones, ultrasonography even in the best hands has limited value in choledocholithiasis. Only approximately 25% to 40% of CBD stones are detected by transabdominal ultrasonography (182). This drawback is somewhat balanced by the ability of ultrasonography to recognize dilatation of the biliary tree beyond 7 mm, a value generally considered the upper limit of the normal choledochus.

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▪ Figure 22.8 Ultrasonographic demonstration of several gallbladder stones. A dependent layer of echogenic biliary sludge can be distinguished from the (black) echolucent bile above it. The stones cast a characteristic shadow, preventing further penetration of the ultrasound into the liver parenchyma.

Computed tomography (CT) scan has limited value in the diagnosis of gallstones for the same reasons as plain radiographs. However, CT scan improves the patient's evaluation by its capability of detecting or excluding complications, such as pancreatitis, pericholecystic fluid, perforation, or abscess formation. More recently, computerized analysis of CT scan data has been used to reconstruct bile duct images to provide a CT cholangiography (183). Oral cholecystography (OCG) was formerly used widely for diagnosing gallstones but has been largely superseded by ultrasonography. It is currently used for patients considered for oral dissolution therapy of gallstones because OCG can assess cystic duct patency and the cholesterol content of the stones. These two characteristics are prerequisites for this form of treatment. Radionuclide scanning or cholescintigraphy after intravenous administration of a technetium-99m– labeled iminodiacetic acid derivative is valuable in assessing cystic duct obstruction in the diagnosis of acute cholecystitis and postoperative bile leaks (184). Nonvisualization of the gallbladder in the appropriate clinical setting is considered 95% sensitive and 80% to 90% specific for acute cholecystitis (181,185). Magnetic resonance imaging (MRI) in its conventional form has little use in gallstone disease. However, magnetic resonance cholangiopancreatography (MRCP), a three-dimensional computer-generated reconstruction of the biliary system, is rapidly evolving as the most useful alternative for other methods of cholangiography (186). The method is noninvasive, does not require contrast agents, and can be done with an imaging time of only a few minutes (187). Moreover, the resolution is rapidly approaching a quality comparable to that of direct cholangiography (188). In the diagnosis of choledocholithiasis, MRCP has been reported to reach a sensitivity of around 95% (189,190). Hence, MRCP, where available, is turning into an increasingly important tool in the diagnosis of choledocholithiasis. Endoscopic ultrasonography (EUS) is also becoming increasingly helpful in the

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assessment of choledocholithiasis (Fig. 22.9), with a sensitivity and specificity of more than 95% (191,192). It is highly efficient in decreasing unnecessary endoscopic retrograde cholangiopancreatographys (ERCPs) (see subsequent text) (193). Moreover, it is superior to transabdominal ultrasonography in diagnosing small gallbladder stones, particularly in obese patients. It is also sensitive for detecting sludge and microcrystals in the gallbladder (194,195). EUS is, however, significantly operator dependent and unfortunately not routinely available in many centers.

▪ Figure 22.9 Endoscopic ultrasonography of the common bile duct (CBD) demonstrating choledocholithiasis.

ERCP has been the gold standard for diagnosing choledocholithiasis for the last two decades (Fig. 22.10) (196). It is an invasive procedure associated with an inherent risk of pancreatitis. The current practice is shifting to MRCP and EUS as diagnostic tools, although ERCP remains the primary modality in managing choledocholithiasis, as discussed in subsequent text. When gallstone disease is suspected but cannot be identified by other means, microscopic examination of duodenal contents aspirated after administration of CCK or bile obtained through an ERCP catheter may be employed to detect microcrystals. Cholesterol monohydrate crystals or calcium bilirubinate granules are readily recognized when the bile sediment is inspected under light microscopy, preferentially using polarized light (152,197). The presence of crystals is indicative of the presence of gallstone disease with sludge or small stones whose size may be below the limits of resolution of the imaging modalities (approximately 1 to 2 mm). The combination of EUS and bile analysis has been shown to be particularly sensitive (194).

Management of Gallstones Management of gallstones is guided by the natural history of the disease (Figs. 22.7 and 22.11) (2). Because P.653 most stones are asymptomatic and will remain so indefinitely, the principal means of dealing with gallstones is expectant management, as supported by

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decision analysis (198). However, the identification of patients with symptomatic stones rests on the clinical history rather than any diagnostic test. Patients with symptomatic stones, including biliary colic, should be offered therapy. Given the low likelihood of complications in patients with just pain, treatment is nonurgent (199). The mainstay of gallstone treatment is cholecystectomy. Removal of the gallbladder with the stones will cure the disease and prevent recurrence. In P.654 circumstances in which surgery is too risky or rejected by the patient, alternative therapeutic options may be considered. Once a complication has occurred, the stones should be dealt with promptly.

▪ Figure 22.10 A: Endoscopic retrograde cholangiopancreatography of common bile duct stone (black arrow) identified after cholecystectomy (white arrow identifies surgical clips on the cystic duct). B: Endoscopic placement of a basket (black arrow) allows extraction of the stone.

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▪ Figure 22.11 Approach to diagnosis and treatment of gallstones. Details of management of complications of gallstones are described in the text. CBD, common bile duct; EUS, endoscopic ultrasonography; MRCP, magnetic resonance cholangiopancreatography; ERCP, endoscopic retrograde cholangiopancreatography; ESWL, extracorporeal shock wave lithotripsy.

Patients with classic symptoms of severe right–upper quadrant or epigastric pain are most likely to gain relief with cholecystectomy (161,162). The conditions of those with nonspecific symptoms such as dyspepsia, bloating, or flatulence are unlikely to be improved with cholecystectomy (200).

Surgical Treatment of Gallbladder Stones The standard treatment for gallstones since 1892 has been cholecystectomy. Removal of the gallbladder under elective circumstances is associated with very low morbidity and mortality (201,202). In the early 1990s, the field underwent a revolution, when the conventional procedure was replaced by laparoscopic cholecystectomy. First introduced in 1987, the laparoscopic approach reduced postoperative pain, allowing patients to be discharged within 1 to 2 days of surgery and rapidly return to their normal activities (203). Less than 5% of laparoscopic cholecystectomies are converted to open procedures in the operating room because of excessive inflammation, adhesions, unexpected findings, or anatomic variations (204,205). Laparoscopic cholecystectomy is associated with a decreased risk of mortality, cardiopulmonary complications, and wound infections, but an increased risk of bile duct injuries (204,206). Initially believed to be part of the learning curve, it has become evident that the rate of bile duct injury remains between 0.2% and 0.5%, even in the most experienced hands (207). Because the advent of laparoscopy has also increased the rate of cholecystectomies performed by 20% to 30% (208), bile duct injuries are not an uncommon complication seen by gastroenterologists or hepatologists.

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The most common immediate problem is bile leak, often manifested by postoperative pain and fever, and is treated easily by prompt endoscopy (209). At ERCP a stent is placed with or without sphincterotomy to decrease outflow resistance and enable spontaneous closure of the leak, usually within a few days. Late complications may be more severe and usually result from bile duct stricturing. Patients may develop asymptomatic cholestasis or jaundice and cholangitis with a risk of secondary biliary cirrhosis if untreated. Endoscopic treatment with balloon dilatation and stent placement is usually effective (210), but specialized surgical repair may be required, particularly in proximal injuries. Although most bile duct injuries are treated efficiently by endoscopy or surgery, they were shown to have a negative effect on overall patient survival (211). Intraoperative cholangiography has been suggested to reduce the risk of bile duct injury, with variable results (211,212). Minilaparotomy has been advocated by some to reduce the risks while retaining the benefits of laparoscopic surgery (213). Timing of surgery in the context of acute cholecystitis has been debated. It was thought that surgery would increase surgical mortality during the acute episode and should, therefore, be deferred to 6 to 8 weeks after recovery from the event. However, when studied prospectively, it appeared that early cholecystectomy within days of presentation is actually associated with less morbidity and mortality and can also be performed safely through laparoscopy (214). Prompt cholecystectomy is particularly indicated in patients with diabetes and elderly patients, who are more likely to develop serious complications from the acute episode. Patients with acute cholecystitis who are too unstable to tolerate general anesthesia and full cholecystectomy will improve if the gallbladder is decompressed by way of a percutaneous or surgical cholecystostomy (215). Removal of the gallbladder typically does not alter digestive function measurably. Approximately 5% of patients will experience increased stool frequency or diarrhea postcholecystectomy, possibly related to increased enterohepatic cycling of the bile salt pool (216). Administration of bile acid binding resins such as cholestyramine is often sufficient to control diarrhea, which usually improves over time (217). Recently, some concern has been raised about an increased risk of intestinal cancer after cholecystectomy (218,219). At most, the risk is only modestly elevated, predominantly in women (220).

Nonsurgical Treatment of Gallbladder Stones Despite the efficient removal of gallbladder stones by surgery, approximately 20% of patients continue to suffer from pain after cholecystectomy (221). Moreover, because nonsurgical expectant management carries a low risk of complications, it can be a reasonable option for mildly symptomatic patients (222). Oral bile acids can dissolve cholesterol gallstones (223,224). Initial efforts employed chenodeoxycholic acid (chenodiol), a primary bile acid of humans. Chenodiol is a strong detergent whose primary mechanism of action is enhancing the micellar lipid solubilizing capacity of bile. Side effects related to its detergency included diarrhea and hepatocellular injury. Subsequently ursodeoxycholic acid (UDCA), a primary bile acid of bears and normally present only in minute amounts in human bile, was found to have equal efficacy for gallstone dissolution, with virtually no toxicity. UDCA also reduces biliary cholesterol secretion, mainly through its inhibitory effect on intestinal cholesterol absorption (225). Although UDCA is not

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P.655 a good detergent in allowing true cholesterol solubilization, cholesterol is effectively dispersed in bile as vesicles, thereby preventing and reversing cholesterol crystallization (226). The main limitation of oral dissolution therapy is that its efficacy is limited to a fraction of patients with cholesterol stones (15% or less) (227). Only small cholesterol stones (preferably 18 mm in diameter) stones may require fragmentation before removal. This is routinely done by a mechanical lithotriptor P.656 through the endoscope. More sophisticated tools, such as contact lithotripsy by pulse laser or shock waves or ESWL, increase the success rate to approximately 90% (241). Temporary or long-term endoscopic stenting may be offered for difficult cases or in high-risk patients. Urgent endoscopic drainage is the treatment of choice and is often lifesaving for patients with ascending bacterial cholangitis (242). Since the advent of laparoscopic cholecystectomy, the timing and means of treating concomitant gallbladder and bile duct stones have been debated extensively (243). Theoretically, there are several possible advantages of the laparoscopic one-stage procedure, but this is often unavailable and there are no concrete data to support the advantages (244). Therefore, choledocholithiasis is usually treated endoscopically to avoid open surgery and the associated morbidity (245). However, extensive use of preoperative ERCP may lead to unnecessary endoscopies and cases of pancreatitis, whereas postoperative ERCP may fail and require reoperation. Intraoperative ERCP is possible, but usually impractical. A reasonable strategy is for patients with a high risk of choledocholithiasis to undergo preoperative ERCP while those with moderate risk can have intraoperative cholangiography and laparoscopic CBD exploration (246). Although the approach should be based on local expertise and preferences, most centers perform a preoperative ERCP when the likelihood of choledocholithiasis is high. A

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dilated CBD with a stone seen on ultrasonography, persistent jaundice, and elevated alkaline phosphatase levels are good predictors of choledocholithiasis (247,248). In less clear cases, MRCP and EUS can be used to guide therapeutic decisions. A recent decision analysis in patients with acute biliary pancreatitis found MRCP and EUS to be most useful for patients with an intermediate probability of choledocholithiasis (249). When the likelihood of choledocholithiasis is low, preoperative ERCP is best avoided (250). When unexpected choledocholithiasis is revealed intraoperatively, a transpapillary guidewire, catheter, or endoprosthesis may be left in place by the surgeon to increase the postoperative success rate of ERCP (251). Occasionally, small stones will pass spontaneously and uneventfully, rendering ERCP unnecessary (252). Percutaneous transhepatic cholangiography (PTC) has limited use in the diagnosis or management of gallstones, except as rescue therapy for patients with choledocholithiasis in whom ERCP has failed. PTC provides effective biliary drainage in the setting of acute cholangitis and enables subsequent successful ERCP by the combined percutaneous and endoscopic approaches (253). A guidewire is introduced percutaneously through the bile ducts into the duodenum and is used to cannulate the bile duct to facilitate sphincterotomy and stone extraction by standard means. If ERCP is unavailable, the more invasive transhepatic route may be used for stone extraction. If patients are at high surgical risks and stones in the common duct can be cleared by endoscopy, it may be reasonable to defer cholecystectomy. Several retrospective and prospective nonrandomized studies have shown that less than 15% of patients develop biliary complications during follow-up (254). Patients with a patent cystic duct at surgery seem to fare particularly well (255). However, a more recent prospective randomized trial has shown that up to 47% of patients may develop biliary symptoms (256). Therefore, whenever possible, surgery should be considered the definitive therapy to minimize recurrent biliary symptoms (257).

Treatment of Microlithiasis Patients with microlithiasis or biliary sludge comprise a special subgroup of patients who may also develop attacks of biliary pain, acute pancreatitis (152), or cholecystitis (55). Microlithiasis is believed to represent an early stage of gallstone disease because, when left untreated, approximately 8% will develop overt gallstones (150). Most often, the sludge will disappear spontaneously, particularly in circumstances of transient lithogenicity such as pregnancy, parenteral nutrition, or rapid weight loss (101,258). Persistent microlithiasis can be treated by oral bile acid therapy, although significant symptoms and complications should be treated by cholecystectomy or endoscopic sphincterotomy, similar to the approach for macroscopic stones (55).

Prevention of Gallstones Because of the high prevalence of gallstones and the high costs involved in their management, the ultimate approach should be prevention. Unfortunately, most attempts to effectively prevent gallstone formation in the general population have failed. The increased recognition of risk factors for gallstone formation has unfortunately not resulted in better means of prevention. Despite recommendations for low-fat, low-calorie diets and moderate alcohol intake with regular physical activity, the prevalence of gallstones has not declined.

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There are, however, some high-risk situations in which prevention is possible. During rapid weight loss, in particular, after bariatric surgery, prophylactic administration of UDCA will reduce the likelihood of gallstone formation from approximately 30% to almost nil (108). In patients receiving TPN, the administration of CCK (259) or early limited enteral feeding to induce gallbladder contraction may prevent the formation of biliary sludge and stones. More widespread preventive measures will hopefully be available as our understanding of the pathophysiology of gallstones progresses and more effective therapeutic agents are discovered. P.657

Annotated References Cooper AD, ed. Bile salts: metabolic, pathologic and therapeutic considerations. Gastroenterol Clin North Am 1999;28:1–229. A volume reviewing bile salt metabolism, the pathogenesis of gallstones, and laparoscopic and nonsurgical therapies. Includes references 15, 38, 203, 223. Kosters A, Jirsa M, Groen AK. Genetic background of cholesterol gallstone disease. Biochim Biophys Acta 2003;1637:1–19. Review focused on the impact of molecular defects in lipid transport offers insights into the development of gallstone disease. National Institutes of Health. NIH State-of-the-Science Conference Statement, Endoscopic Retrograde Cholangiopancreatography (ERCP) for Diagnosis and Therapy; January 14–16, 2002. Available at: http://www.consensus.nih.gov/2002/2002ERCPsos020Program.pdf accessed November 25, 2005. Results of NIH consensus conference, including abstracts from experts in the field and a comprehensive bibliography. Ransohoff DF, Gracie WA, Schmittner JP, et al. Guidelines for the treatment of gallstones. Ann Intern Med 1993;119:620–622. Still pertinent clinical review and practice guidelines, with the scientific rationale underlying relevant clinical studies.

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Editors: Title:



Copyright ©2007 Lippincott Williams & Wilkins > Table of Contents > Volume I > Section IV - Cholestatic Disorders > Chapter 23 - Primary Sclerosing Cholangitis

Chapter 23 Primary Sclerosing Cholangitis Konstantinos N. Lazaridis Nicholas F. Larusso

Key Concepts z

Primary sclerosing cholangitis (PSC) is a progressive, cholestatic liver disease that is characterized by diffuse chronic inflammation and fibrosis of the biliary tree.

z

PSC affects primarily young to middle-aged men and frequently is associated with inflammatory bowel disease (IBD), most often chronic ulcerative colitis (CUC).

z

The cause of PSC remains unknown, although the interaction of exogenous factors with the genetically predisposed individual is likely critical in disease pathogenesis.

z

z

Cholangiocarcinoma is the most feared complication of PSC; however, colon cancer complicating CUC in a patient with PSC is important as well. The prognosis of PSC is variable, but in general the disease process is progressive.

z

To date, no medical therapy is available benefit although a variety of pharmacologic agents have been tested; nevertheless, high-dose ursodeoxycholic acid deserves further study in the context of randomized controlled trials.

z

Liver transplantation is the best available treatment option for patients with advanced PSC; however, the disease can recur in 20% of recipients after successful transplantation.

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease of unknown causation that is frequently associated with inflammatory bowel disease (IBD). The disorder is characterized by diffuse inflammation and fibrosis of the biliary tree and usually leads to biliary cirrhosis, which can be complicated by portal hypertension and hepatic failure. PSC was first described by Delbet in 1924 (1). Before the widespread availability of endoscopic retrograde cholangiopancreatography (ERCP) in mid-1970s, PSC was considered a rare disease (2). At present, PSC is seen as an important cause of chronic cholestasis in adults. However, it is still unclear whether the prevalence of the disease has increased in recent decades. The greater availability of ERCP and magnetic resonance cholangiopancreatography (MRCP) as well as the recognized association of PSC with IBD along with screening of these

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patients with liver tests have probably enhanced the frequency of PSC diagnosis. To date, we have better understanding of the natural course of PSC, although the cause and identification of specific beneficial therapies have eluded investigators so far.

Epidemiology Two recent epidemiologic studies from the United States and United Kingdom described the incidence and prevalence of PSC in the community setting. The first study from Olmsted county, Minnesota, estimated the age-adjusted incidence of PSC to be 0.9 per 100,000 individuals with point prevalence of 13.6 per 100,000 persons in 2000 (3). Specifically, the age-adjusted incidence was 1.25 and 0.54 per 100,000 men and women, respectively (3). The estimated prevalence was 20.9 per 100,000 for men and 6.3 per 100,000 women (3). On the basis of this study, it was projected that P.666 approximately 29,000 cases of PSC exist in the white USA population. Moreover, the median age at PSC diagnosis was 40 years, 68% (15 of 22) of the patients were men and 73% (16 of 22) of the patients had concurrent IBD (3). The second study from the city and county of Swansea, Wales, UK reported an annual incidence of 0.91 per 100,000 and a point prevalence of 12.7 per 100,000 individuals (July 1, 2003) (4). The median age at PSC onset was 52 years, 62% (33 of 53) of the patients were men, and 62% (33 of 53) of the patients had coexisting IBD (4). Although these two studies have shed light on the epidemiology of the disease, additional population-based studies are required to better define the prevalence and natural history of PSC, a chronic cholestatic liver disease that leads not only to hepatic failure but also predisposes to malignancies of the colon and liver.

Pathogenesis To date, the exact pathogenesis of PSC remains unknown, although a number of avenues have been explored over the past three decades. A consensus pathogenesis postulates that PSC develops as the result of acquired exotoxins, infectious agents or autoimmunity interacting with predisposing host factors (Fig. 23.1). It is proposed that this interplay leads to an initial damage of cholangiocyte, the target epithelial cell that lines the bile ducts. Subsequently, a biliary inflammatory response takes place but most individuals likely recover (i.e., resolution) without consequences. However, it is the genetic predisposition of the host and probably other unknown mechanisms that contribute to persistance of inflammation of the bile ducts resulting in progressive biliary destruction and complications of PSC such as chronic cholestasis, biliary cirrhosis, and cholangiocarcinoma (Fig. 23.1).

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▪ Figure 23.1 Proposed pathogenesis of primary sclerosing cholangitis.

Genetic Factors Several observations are consistent with an important role for genetic factors. First, familial PSC cases have been reported (5). Second, a recent report indicated the increased prevalence of PSC among first-degree relatives of patients who are affected (6). These authors calculated an almost 100-fold relative risk of developing PSC in families with an affected member, thereby supporting the presence of inherited elements in disease pathogenesis. In addition, several case control studies have demonstrated the genetic predisposition to PSC development by identifying genetic variants associated with patients compared to controls. To this extent, Chapman first reported the HLA B8 frequency to be significantly higher in patients with PSC (60%) compared with controls (25%) (P < 0.001) (7). Subsequently, Donaldson demonstrated an association of PSC with the HLA-A1, B8, DR3 haplotype (40% in cases vs. 12% in controls, P < 0.0005) (8). Moreover, in the past 5 years, genetic polymorphisms (i.e., DNA variants) associated with susceptibility to PSC have been reported including (i) the promoter region of the tumor necrosis factor-α (TNF-α) receptor (9); (ii) stromelysin (i.e., matrix metalloproteinase 3) (10); (iii) major histocompatibility complex class I related-MIC gene family (MICA) gene (i.e., P.667 MICA) (11); (iv) CCR5-Delta 32 mutation (12); and (v) intracellular adhesion molecule-1 ICAM-1 (i.e., intracellular adhesion molecule-1) (13) (Table 23.1). From a theoretical standpoint, the variety of susceptible genes interacting with environmental factors likely explain the heterogeneity of PSC phenotype as this relates to disease development, progression and complications. It is expected that many genetic variants (i.e., susceptible alleles) predispose to disease, each contributing a small effect on the PSC phenotype. To this end, large association

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(i.e., case-control) and familial studies are needed to better dissect the genetic susceptibility of PSC before we develop novel diagnostic tools and intervening therapies.

Table 23.1. Susceptibility Genes in Primary Sclerosing Cholangitis

Gene TNF-α

Type Cytokine

Variation G/A,

Reference (9)

substitution

Stromelysin

Matrix

5A/6A alleles

(10)

*002/*008

(11)

metalloproteinase

MICA

MHC molecule

alleles

CCR5-Delta 32

Chemokine

32 base pair deletion

ICAM-1

Adhesion molecule

K469E

(12)

13

TNF-α, tumor necrosis factor α; MICA, major histocompatibility complex class I related-MIC gene family; MHC, major histocompatibility complex; CCR5-Delta 32, chemokine, CC motif receptor 5; ICAM-1, intracellular adhesion molecule-1.

Other Proposed Hypotheses of Primary Sclerosing Cholangitis Pathogenesis Because of the finding that IBD coexists in approximately 75% of patients with PSC, much interest has been paid to the potential role of an inflamed colon in causing the liver disease (14). For long it was believed that inflammation of the colon may increase the colonic permeability to various intraluminal products leading to liver injury. To this extent, bacteria or bacterial toxins have been considered but have not been convincingly demonstrated to play a pathogenetic role in PSC (15,16). In addition, abnormal bile acids generated by bacterial action in the diseased colon and directly absorbed through the colonic mucosa into the portal system have been suggested as a possible etiology of PSC. Nevertheless, no direct evidence in support of this theory has been forthcoming (17). In an animal model, inflammatory bacterial peptides led to portal inflammation and histologic changes suggestive of PSC (18,19). In this model, a variety of agents were useful in blocking this response, including an inhibitor of tumor necrosis factor (TNF). However, when pentoxifylline, a TNF inhibitor, was used in patients with PSC, no beneficial effect was found, and doubt was cast on the value of this model in understanding the disease in humans (20). Furthermore,

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the finding that PSC can develop in approximately 25% of patients without concurrent IBD, the lack of association between the severity of the colonic inflammation and the likelihood of PSC development and the fact that proctocolectomy for chronic ulcerative colitis (CUC) does not affect the natural history of PSC (21) speak against an essential role of the inflamed colon in development of the cholestatic liver disease. At present, there is no convincing evidence of a virus or other microorganism causing PSC. The usual hepatotrophic viruses (i.e., hepatitis A virus [HAV], hepatitis B virus [HBV], and hepatitis C virus [HCV]) have been excluded. Cytomegalovirus can produce changes suggestive of PSC in patients with acquired immunodeficiency states, but in patients with competent immune function, no evidence of cytomegalovirus infection has been found (22). Reovirus type 3 was considered a possible causative agent but further work excluded it as an etiology for PSC (23).

Table 23.2. Diseases Associated with Primary Sclerosing Cholangitis

Inflammatory bowel disease Autoimmune hepatitis Chronic pancreatitis Celiac disease Rheumatoid arthritis Retroperitoneal fibrosis Peyronie's disease Riedel's thyroiditis Bronchiectasis Sjögren's disease Glomerulonephritis Systemic lupus erythematosus Pseudotumor of the orbit Vasculitis Autoimmune hemolytic anemia Immune thrombocytopenic purpura Angioimmunoblastic lymphadenopathy Histiocytosis X Cystic fibrosis Sarcoidosis Systemic mastocytosis Polymyositis Alopecia universalis Thymoma Ankylosing spondylitis

P.668 Immune-mediated damage of bile ducts seems a plausible mechanism leading to PSC. Abnormalities of the humoral immune system in PSC include the presence of (i) hypergammaglobulinemia, particularly elevated immunoglobulin M levels, (ii) circulating immune complexes; and (iii) activated complement (24). Moreover, patients with PSC have serum positivity for several auto-antibodies including antineutrophil cytoplasmic antibodies (ANCA), anticardiolipin antibodies and

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antinuclear antibodies (53%) (25). In addition, the cellular immune system in PSC can be abnormal as indicated by the decrease in the total number of circulating T cells caused due to a decline in CD8 (suppressor/cytotoxic cells) and an increase in circulating B-cells. On the other hand, the documented aberrant expression of HLA class II antigens on the biliary epithelial cells may serve to target an immune response against the biliary cells; (26,27) Although the presence of ICAM-1, which serves as a ligand for the leukocyte functionassociated antigen (LFA-1), may help form connections between T-lymphocytes and antigen-presenting cells. Indeed, increased levels of ICAM-1 have been found in both the bile duct epithelial cells and serum (27,28,29). LFA-1 also appears to be overexpressed by intrahepatic lymphocytes, but this expression may simply be induced by proinflammatory cytokines (30). Despite all these observations, the documented altered immune status may simply be an epiphenomenon and yet not linked directly to PSC pathogenesis.

Clinical Features PSC affects men almost twice as commonly as it does women and the average age at diagnosis is the early 40s (3). In the past two decades, a frequent clinical scenario of diagnosis includes patients who are asymptomatic and come to medical attention solely because of abnormal liver tests. Contrary symptoms of advanced stages of PSC such as jaundice, pruritus, fever, or manifestations of portal hypertension are less common as initial presentation. Physical examination may be unrevealing. Hepatomegaly, splenomegaly, hyperpigmentation, and skin excoriation can be found. Health-related quality of life is significantly impaired among patients with PSC similar to that found in other chronic liver diseases, such as primary biliary cirrhosis (PBC) and chronic viral hepatitis. (31,32). PSC usually affects the entire biliary tree. Approximately 20% of patients have involvement of the intrahepatic bile ducts alone and approximately 5% of patients have disease involving the interlobular and septal bile ducts (i.e., smallduct PSC) seen only in liver biopsy specimens while ERCP is normal (33,34,35,36). Another clinical entity is the overlap syndrome in which PSC and autoimmune hepatitis coexist and occurs in approximately 5% of patients (33,34,35). PSC afflicts children rarely (37). In this population, the disease seems to have more frequent features of autoimmune hepatitis (38,39).

Laboratory Findings Biochemical Testing The biochemical findings of patients with PSC are nonspecific. Neverthelesss, chronic biochemical cholestasis is apparent. Alkaline phosphatase is the most commonly elevated liver enzyme; however, the occasional patient with welldocumented PSC but normal alkaline phosphatase levels has been described (40). Aminotransferase levels frequently are elevated and the degree of elevation is usually only modest except in patients with overlap syndrome in whom these levels could be markedly increased. Serum bilirubin is typically normal but in patients with advanced disease can reach very high levels.

Immunologic Testing Overall, there are no immunologic or autoantibody profiles specific for PSC.

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Hypergammaglobulinemia occurs in approximately 25% of patients with PSC and immunoglobulin M is the most commonly elevated component. PSC patients have serum positivity for several auto-antibodies including ANCA (84%), anticardialipin antibodies (66%) and antinuclear antibodies (53%) (25). Antimitochondrial antibodies are rare in patients with PSC.

Imaging Studies Visualization of the biliary tree is essential for establishing the diagnosis of PSC. ERCP has been the diagnostic procedure of choice, although MRCP is almost equally sensitive and specific for detection of the disease. Additionally, MRCP is more cost-effective for establishing the diagnosis in patients with suspected PSC (41,42,43). Percutaneous transhepatic cholangiogram (PTC) can be used to evaluate the bile ducts for PSC but because of the frequently sclerotic intrahepatic biliary system gaining access through the percutaneous route could be challenging. Typical cholangiographic findings of PSC include multifocal stricturing and beading, usually involving both the intrahepatic and extrahepatic biliary system (Fig. 23.2). Involvement of the intrahepatic tree alone can be found in as many as 20% of patients (44,45). Often the strictures are diffusely distributed, short P.669 in length and annular. Cystic duct and gallbladder involvement are present in as many as 15% of patients (46). During cholangiography, the presence of polypoid masses should raise the suspicion of cholangiocarcinoma, although the diagnosis of the latter can be very difficult to establish.

▪ Figure 23.2 ERCP of a patient with primary sclerosing cholangitis. Extensive extrahepatic and intrahepatic biliary disease is evident.

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Histology Liver biopsy findings are usually not enough to establish the diagnosis of PSC. The classic onion-skin fibrosis is present in fewer than 10% of biopsy specimens obtained from patients with PSC, but when seen is almost pathognomonic (Fig. 23.3) (47). The histologic grading system, proposed by Ludwig et al. (47), has four stages: Stage 1, portal; stage 2, periportal; stage 3, septal; and stage 4, cirrhosis (Table 23.3). Of interest, in patients with PSC, the histologic changes seem to be quite varied in different segments of the same liver at any given point in time. To this end, histologic staging has been avoided as a component of the most recent survival model of PSC (48).

▪ Figure 23.3 The “onion-skin fibrosis” lesion is characteristic of primary sclerosing cholangitis but is not typically found in liver biopsy specimens from patients.

Table 23.3. Histologic Staging of Primary Sclerosing Cholangitis

Portal stage

Portal edema, inflammation, ductal proliferation;

(stage 1)

abnormalities do not extend beyond the limiting plate.

Periportal stage (stage 2)

Periportal fibrosis, inflammation with or without ductular proliferation; piecemeal necrosis may be present.

Septal stage

Septal fibrosis or bridging necrosis can be identified.

(stage 3)

Cirrhotic stage

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Biliary cirrhosis.

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(stage 4)

Diagnostic Criteria and Differential Diagnosis The diagnostic criteria for PSC were first formulated nearly 40 years ago (49). These criteria included (i) absence of previous surgical trauma to the biliary tree; (ii) lack of stones in the gallbladder and common bile duct; (iii) stenosis/stricturing involving most of the biliary system; and (iv) exclusion of biliary malignant disease. Because of the advent of ERCP in the mid-1970s, the diagnosis can be made without surgery. More recently, the availability of MRCP as a screening test for patients with suspected PSC made noninvasive diagnosis possible (41,42,43). At present, the diagnostic criteria for PSC include (i) typical cholangiographic abnormalities involving any part of the biliary tree; (ii) compatible clinical and biochemical findings (i.e., cholestasis for more than 6 months); and (iii) exclusion of other causes of secondary sclerosing cholangitis (Table 23.4). Liver biopsy has been used in the past to help confirm the diagnosis, although the specificity and sensitivity of the biopsy have come under question. Histologic findings are not always found of value in the most recently developed prognostic scoring systems for patients with PSC (48,50,51,52). However, liver biopsy is useful in the care of a patient with suspected PSC but normal cholangiographic findings (i.e., small-duct PSC) and in the setting of a patient with overlap syndrome. The differential diagnosis of PSC is outlined in Table 23.4.

Table 23.4. Diagnostic Criteria for Primary Sclerosing Cholangitis

Typical cholangiographic abnormalities involving any part of the biliary tree Compatible clinical (cholestatic symptoms, history of inflammatory bowel disease) and biochemical findings (twofold to threefold increase in serum alkaline phosphatase level for longer than 6 m) Exclusion of identifiable causes of secondary sclerosing cholangitis: AIDS cholangiopathy Bile duct neoplasm (unless diagnosis of PSC previously established) Biliary tract surgery, trauma

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Choledocholithiasis Congenital abnormalities of biliary tract Caustic sclerosing cholangitis Ischemic stricturing of bile ducts Toxicity or stricturing of bile ducts related to intra-arterial infusion of floxuridine

AIDS, acquired immunodeficiency syndrome, PSC, primary sclerosing cholangitis.

P.670

Natural History PSC is usually a progressive disease. In a retrospective study with 174 patients with PSC from the United States, the median survival rate from the time of diagnosis was approximately 12 years, which was less than that for an agematched population (53). In another study from Norway, investigators estimated the median survival time of patients with PSC to be 17 years (51,54). Recent population-based epidemiologic data also reported that PSC is a progressive disease and shortens life expectancy. Indeed, studies from Olmsted county, Minnesota, USA and Swansea county, Wales, UK that the liver transplantation free-survival was 65% at 10 years after the diagnosis of PSC and significantly less than the age- and sex-matched populations (Fig. 23.4) (3,4) This information further suggests that PSC is a progressive disease, and if suitable therapy were available, treatment early in the course of the disease would seem warranted.

▪ Figure 23.4 Transplant-free survival of Olmsted, Minnesota, USA (A) and Swansea, Wales, UK (B) patients with primary sclerosing cholangitis compared with age- and sex-mathed population controls from the corresponding counties. PSC, primary sclerosing cholangitis. (Reprinted with permission from Bambha, et al. Gastroenterology 2003;125:1364–1369; and

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Kingham, et al. Gastroenterology 2004;126:1929–30.)

Given the natural history studies, prognostic models have been developed to more accurately forecast an individual patient's disease progression, and thereby, define the best timing for liver transplantation. Using the Cox multivariable regression analysis the variables for these prognostic models were detected (48,50,51,52). To this end, the revised Mayo PSC natural history model employs five independent and reproducible parameters (i.e., age, total bilirubin, albumin, aspartate aminotransferase, and history of variceal bleeding) to estimate the survival of patients (48). Recently, the Model of End-stage Liver Disease (MELD) score has been widely used to prioritize PSC patients with end-stage liver disease before undergoing liver transplantation (55). The natural history of patients with small-duct PSC is usually better compared to those suffering from classic PSC (56). Nevertheless, in some patients with smallduct PSC the disease can progress to classic PSC with typical cholangiographic features if these cases are followed up for several years (56). Finally, secondary sclerosing cholangitis has worse outcome compared to PSC (57). Finally, PSC predisposes to development of colon cancer and cholangiocarcinoma (see subsequent text). Indeed, patients with PSC and CUC have a significantly greater risk of developing colon cancer compared with patients having CUC only (58). Therefore, patients with PSC should undergo surveillance colonoscopies annually. P.671

Associated Diseases A variety of diseases aside from IBD have been associated with PSC (Table 23.2). It is unclear however, whether these associations are true, and therefore share a pathogenetic mechanism, or occur by chance and represent the reporting of two uncommon diseases. The close association of PSC with IBD, particularly CUC, is now widely recognized. This association is found in 70% to 80% of patients with PSC. Crohn's disease has been reported as the cause of colitis in 10% to 15% of patients with PSC (14,59). However, Crohn's disease involving only the small intestine has not yet been described in patients with PSC. There is no clear temporal association between the diagnosis of PSC and IBD, although in general, the diagnosis of the latter is usually established before the liver disease is clinically apparent. Nevertheless, there are well-documented cases of IBD occurring years after the diagnosis of PSC. Similarly, patients can acquire PSC many years after proctocolectomy for colitis (21). In patients with PSC and colitis, the bowel disorder is one of relatively quiescent disease. However, the risk of development of colon cancer in patients with coexisting PSC and CUC seems to be substantially greater than if patients did not have PSC. There has been no association between the severity of bowel disease and the severity of liver disease, and therapy for the bowel disease does not affect the liver disease. Moreover, the most aggressive therapy for the bowel disease, proctocolectomy, has had no effect on PSC (21). Finally, there are no convincing differences in the liver disease of PSC patients with IBD compared to those without the latter.

Management

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The complications of PSC can be due to (i) advanced-stage liver disease (i.e., portal hypertension, decompensated cirrhosis, and hepatic failure); (ii) chronic cholestasis; (iii) the underlying disease (i.e., specific for PSC). The management of complications of portal hypertension, decompensated cirrhosis, and hepatic failure is discussed in Chapters 11, 12, and 33. The management of complications related to chronic cholestasis and those specific for PSC are discussed in subsequent text. Chronic cholestasis can lead to pruritus, fat-soluble vitamin deficiency, metabolic bone disease, and steatorrhea. Specific PSC complications include gallstones and choledocholithiasis, dominant biliary strictures, cholangiocarcinoma and peristomal varices.

Table 23.5. Medications Used for the Management of Pruritus

Medication

Dosage

Ursodeoxycholic acid

15–30 mg/kg/d orally

Cholestyramine

4 g three to four times/d orally

Naltrexone

50 mg/d orally

Rifampin

150 to 300 mg two times/d

Management of Complications of Chronic Cholestasis Pruritus Although not common, pruritus can be disabling and associated with a diminished quality of life. The pathogenesis of pruritus in cholestasis is unknown, although endogenous opioids and retention of substances usually excreted in the bile have been considered (60,61,62). The intensity of the pruritus does not seem to parallel the severity of the liver disease, and pruritus may diminish as the disease progresses. Ursodeoxycholic acid (UDCA), cholestyramine, antihistamines and rifampin as well as opiate receptor antagonists have been used to treat patients with cholestatic pruritus (63,64). The usual doses of these medications are shown in Table 23.5. It is important to remember that rifampin, which can relieve pruritus in 3 to 5 days, can be associated with a reversible hepatotoxicity in approximately 15% of cases. Therefore, it is important to monitor the liver tests closely if this drug is used.

Fat-soluble vitamin deficiency Fat-soluble vitamin deficiency is relatively common among patients with PSC, particularly as the patient progresses toward liver transplantation (65). As many as 40% of patients in some series have vitamin A deficiency; vitamin D and vitamin E deficiencies have been found among 14% and 2% of patients respectively (65). Vitamin K deficiency is uncommon. If this condition is suspected, a short trial of 10 mg water-soluble vitamin K can be considered. If

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the prothrombin time responds after a few doses, long-term therapy should be recommended. Vitamin E deficiency is rare and unfortunately once established can be very difficult to correct with replacement therapy. The usual fat-soluble doses of vitamin replacement therapy are shown in Table 23.6.

Metabolic bone disease Metabolic bone disease, usually caused by osteoporosis rather than osteomalacia, is relatively common and an important complication among patients with PSC (66). Glucocorticoids used to treat accompanying IBD aggravate the osteoporosis. Unfortunately, there is no proven therapy that can help these patients. Use of estrogen P.672 replacement therapy by women should be considered. Calcitonin does not appear to be useful to patients with osteoporosis associated with PBC but it has not been tested in the treatment of patients with PSC. Bisphosphonates have been used with varying results to treat patients with PBC but have not been tested in PSC (67,68). Patients with PSC and IBD undergoing long-term glucocorticoid therapy for the latter, may benefit from oral administration of vitamin D and calcium, particularly those with bone density in the range of osteopenia (T score Table of Contents > Volume I > Section IV - Cholestatic Disorders > Chapter 25 - Postoperative Jaundice

Chapter 25 Postoperative Jaundice Santiago J. Munoz Mary T. Killackey

Key Concepts z

The causes of postoperative jaundice can be grouped under four major categories: Decompensation of preexisting chronic liver disease, cholestatic disorders, necroinflammatory liver diseases, and overproduction of bilirubin.

z

A careful review of the surgical, anesthetic, transfusion, and pharmacologic treatment records, as well as history and physical examination are the initial steps in the evaluation of a patient with postoperative hepatic dysfunction.

z

Additional laboratory tests and imaging studies are frequently necessary to exclude common liver disorders and biliary obstruction.

z

These additional tests plus the information from the review of records and pattern and timing of liver biochemical abnormalities generally lead to the etiology of postoperative jaundice.

z

Patients with chronic liver disease unrecognized before surgery are at risk of developing jaundice, and even liver failure, in the postoperative period.

z

Postoperative jaundice caused by overproduction of bilirubin is characteristically associated with an isolated increase in unconjugated serum bilirubin in the setting of large volume transfusion, hematomas, or hemolytic disorders.

z

Postoperative cholestasis (i.e., marked increase in alkaline phosphatase and bilirubin levels) should lead to suspicion of either biliary obstruction or entities associated with intrahepatic cholestasis.

z

Hepatocellular necrosis caused by hepatic ischemia or acetaminophen and inflammatory disorders (viral and other

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hepatitides) should be suspected when the postoperative hepatic dysfunction is expressed by prominent elevation of aminotransferase levels.

Patients who develop jaundice after a surgical procedure present a unique set of challenges to the clinician and require a careful assessment. Although in many instances the hepatobiliary abnormalities gradually resolve over time, often without specific intervention, in some patients the onset of postoperative jaundice may reflect a serious and potentially life-threatening complication. Because clinically significant liver injury can develop in the absence of jaundice, unless stated otherwise, the term postoperative jaundice is used in this chapter to also include abnormalities of other liver blood biochemical tests. There are often multiple factors present simultaneously in the postoperative patient that may lead to postoperative jaundice (1,2,3). The investigation of postoperative hepatic dysfunction is optimally accomplished as a joint enterprise by surgeons and physicians evaluating the patient's evolving clinical picture. This review presents a practical yet comprehensive approach to the diagnosis and management of a patient who develops postoperative jaundice. P.698

Evaluation of Preoperative Risk Factors for Jaundice The evaluation of a patient with postoperative jaundice begins with a careful review of preoperative and operative data, including operating room and anesthesia records. Key preoperative data to be analyzed include medical history, main symptoms, and physical examination performed before the surgical procedure. Preoperative clues for liver disease can be further investigated, if necessary, with the patient or family members. Questions on the existence of known chronic liver disease, use of therapeutic or illegal drugs, and a detailed history of alcohol consumption should be obtained. Preoperative diabetes mellitus, obesity, female gender, hyperlipidemia, and other features of the metabolic syndrome suggest that the patient may have underlying nonalcoholic fatty liver disease (NAFLD) or its more aggressive variant, nonalcoholic steatohepatitis (NASH) (4). Historical risk factors for acquisition of hepatitis B virus (HBV) or hepatitis C virus (HCV) infection, such as a history of intravenous drug use or blood products transfused before 1992, should prompt the determination of HCV antibody and hepatitis B surface antigen (HBsAg) status. A history of recurrent mild jaundice based on unconjugated hyperbilirubinemia suggests Gilbert's syndrome. Although the postoperative patient with Gilbert's syndrome may develop more pronounced jaundice, the prognosis is excellent and no further investigations are necessary other

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than documenting a predominantly indirect hyperbilirubinemia. A review of preoperative physical examination records may reveal signs of the existence of underlying chronic liver disease, which perhaps went unrecognized preoperatively. Spider telangiectasis, gynecomastia, palmar erythema, Dupuytren's contractures, hepatomegaly, and/or splenomegaly would suggest preexisting chronic liver disease. Evaluation of preoperative laboratory data can also be useful to assess for the presence of preexisting chronic liver disease. Elevated alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels suggest chronic hepatitis, whereas the existence of preoperative thrombocytopenia (even mild), depressed serum albumin level, and/or prolonged prothrombin time suggest the presence of cirrhosis, which may have been otherwise well compensated before the surgical procedure. Similarly, preoperative imaging studies revealing hepatosplenomegaly and/or intra-abdominal varices are helpful in raising the suspicion of preexistent cirrhosis. After major surgery, patients with cirrhosis have a distinct risk of decompensation (i.e., development of jaundice, ascites, hepatic encephalopathy, or portal hypertensive gastrointestinal bleeding). Furthermore, patients with cirrhosis are more susceptible to hepatic ischemia during intraoperative arterial hypotension or hypoxemia. This in turn can be expressed postoperatively as onset of abnormal liver biochemistries or even frank hepatic decompensation. In general, the probability of postoperative decompensation and liver failure is related to the existence of residual hepatic reserve before the surgical procedure. This has been traditionally evaluated by determining the patient's Child-Turcotte-Pugh class (5,6). Child-Pugh class A patients are considered to have a probability of decompensation of 10% or less, whereas Child-Pugh class B or C carries postoperative mortality risks of 20% to 30% or 40% to 60%, respectively. Therefore, learning that the patient with postoperative jaundice had a diagnosis of cirrhosis made preoperatively can be important in the evaluation, management, and prognosis of hepatic dysfunction. More recently, the postoperative risk evaluated by the more objective Model for End-Stage Liver Disease (MELD) score was found to be superior to Child-Pugh method in predicting outcome (7,8). When evaluating a patient with postoperative jaundice or abnormal liver biochemistries, it is reasonable to check the basic viral hepatitis serologies, iron indices, and antinuclear and smooth muscle autoantibodies and obtain a complete abdominal imaging study. If the etiology remains obscure and the abnormalities persist or worsen, additional investigations are warranted. It is important to note that in chronic infection with HCV, and also in other hepatic diseases, cirrhosis may be present in spite of normal aminotransferase levels (i.e., ALT,

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AST).

Causes of Postoperative Jaundice A large number of conditions may lead to postoperative hepatobiliary dysfunction (1,2,3). The main causes can be grouped into four main categories: Cholestatic problems including extrahepatic cholestasis (obstructive jaundice) and intrahepatic cholestasis, necroinflammatory liver diseases, excessive production of bilirubin, and preexisting hepatobiliary disease that becomes apparent postoperatively. The pattern and timing of the abnormalities can be helpful to narrow the differential diagnosis (Tables 25.1 and 25.2).

Postoperative Jaundice due to Biliary Obstruction Major abdominal surgery can be associated with postoperative jaundice. Classic examples include open P.699 aortic surgery, esophageal surgery, and other procedures involving or adjacent to the porta hepatis. In particular, the occurrence of acalculous cholecystitis after open cardiac or aortic surgery should be kept in mind. Insertion of hepatic arterial infusion pumps with administration of chemotherapy can also lead to cholecystitis, and even to secondary sclerosing cholangitis. Acute portal vein thrombosis is a rare but severe complication after major upper abdominal surgery or in patients with inflammatory bowel disease (9). Acute postoperative portal vein thrombosis can lead to liver failure if not promptly treated. Suspicion should be high in the setting of conditions associated with hypercoagulable states. Idiosyncratic forms of liver dysfunction have also been reported with large abdominal surgery (10). Surgery of the biliary tract may be followed by postoperative jaundice. Patients undergoing cholecystectomy for gallstones may have retained stones, or worse, a bile duct injury (11). Generally, patients present 3 to 4 days after surgery; although in a recent large study, the mean time to referral for bile duct injury was 3 weeks (12). Patients often present with severe right upper quadrant pain or even generalized peritonitis. Fever, nausea, and vomiting may also be present. Variable elevation of the total bilirubin, alkaline phosphatase, and aminotransferase levels can be present. Immediate evaluation with hepatobiliary ultrasonography and magnetic resonance cholangiopancreatography (MRCP) should be obtained to investigate biliary leak, biloma, or abscess. Hydroxy iminodiacetic acid (HIDA) biliary scan may be useful if MRCP is not readily available. Endoscopic retrograde cholangiopancreatography (ERCP) is often subsequently used for confirmation of the diagnosis and therapeutic intervention. If stones are present, removal with or without sphincterotomy is indicated (13,14). If a cystic or bile duct leak is found, placement of an internal

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biliary stent is often helpful. In patients who present very late, a biliary stricture may be found. Balloon dilatation, with repeated biliary stent changes, is the first line of therapy (15). If this fails, or in more acute and severe injuries such as complete transection, surgical exploration with repair is necessary (16). In a recent review of 200 patients treated over 13 years for bile duct injury after laparoscopic cholecystectomy, 175 required some form of surgical intervention (12). Jaundice was present in 50%, whereas bile leak, cholangitis, biloma, and uncontrolled sepsis were evident in 59%, 35%, 5%, and 3%, respectively. Early referral to a tertiary care center with surgeons experienced in hepatobiliary surgery is important to minimize complications, number of required surgeries, and overall mortality. Immediate repair appears preferable but if diagnosis is delayed, control of sepsis and persistent bile leak should first be accomplished. Once peritonitis has resolved, biliary reconstruction can be scheduled after 2 to 8 weeks. P.700 Specialized endoscopy and interventional radiology are helpful adjuncts for the successful care of these patients.

Table 25.1. Causes of Postoperative Obstructive Jaundice and Time of Presentation

Within 2 to 3 wk of surgery Decompensation of preexisting chronic liver disease Overproduction of bilirubin: Hematomas, transfusions, hemolysis Hepatic ischemia: Vascular injury, cardiac failure, shock, bleeding, hypoxemia Benign postoperative intrahepatic cholestasis Biliary obstruction: Retained stones, bile duct injury or leak, pancreatitis Therapeutic drug liver injury: Acetaminophen, other drugs Gilbert's syndrome After 2 to 3 wk of surgery Therapeutic drug-induced liver injury Total parenteral nutrition Viral hepatitis

Modified from Baker A, Green R. Postoperative jaundice. In: Schiff E, Sorrell M, Maddrey W, Eds. Diseases of the liver. 9th Ed. Philadelphia: Lippincott Williams & Wilkins, 2003.

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Table 25.2. Common Patterns of Liver Blood Test Abnormalities in Postoperative Jaundice

Mechanism of postoperative jaundice

Pattern

Bilirubin

Isolated increase in unconjugated

overproduction

bilirubin level, occasionally mild increase in AST, ALT levels

Hepatic ischemia

Mild to severe elevation of ALT, AST, and LDH levels; bilirubin level elevation and prothrombin time prolongation in severe cases; normal AP and albumin concentration

Viral and drug-

Variable increase in the levels of

induced hepatitis

bilirubin, ALT, AST, and AP; broad spectrum of abnormalities

Biliary obstruction

Moderate increase in level of bilirubin, marked increase in AP level, and mild to moderate increase in ALT and AST levels

Benign

Mild to marked increase in bilirubin

postoperative

and AP levels

intrahepatic cholestasis

Gilbert's syndrome

Mild increase in unconjugated bilirubin content

AST, aspartate amino transferase; ALT, alanine aminotransferase; LDH, lactate dehydrogenase; AP, alkaline phosphatase. Modified from Baker A, Green R. Postoperative jaundice. In: Schiff E, Sorrell M, Maddrey W, Eds. Diseases of the liver. 9th Ed. Philadelphia: Lippincott Williams & Wilkins, 2003.

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Postoperative jaundice is predictable in patients undergoing biliary reconstruction for benign or malignant disease. Swelling at anastomotic sites is thought to be responsible, and normalization of liver blood test results may take several days. If laboratory test results do not resolve, bile leak or stricture must be ruled out. Hepatic resections can lead to postoperative jaundice, although usually of transient duration. However, if there is underlying liver disease, or a substantial portion of normal liver was resected, patients may have more severe, even progressive, liver dysfunction. The course of this form of hepatic failure usually extends over days to weeks, with sepsis frequently responsible for death. If not contraindicated, liver transplantation may be necessary. When an extensive hepatic resection is anticipated, preoperative techniques such as selective portal vein embolization or ligation may be performed to induce growth of the lobe that is free of disease (17,18). Rarely, postoperative jaundice can be seen in patients who develop pancreatitis after surgery. Often, this is associated with large procedures such as open cardiac or aortic cases (19,20). However, pancreatitis can develop after gastric or splenic procedures as well. Edema of the pancreatic head with external compression of the bile duct probably plays a role in the pathogenesis. Liver blood biochemical test results gradually resolve as the pancreatitis subsides.

Postoperative Intrahepatic Cholestasis A predominant abnormality of alkaline phosphatase and bilirubin levels in the absence of large duct obstruction clinically defines intrahepatic cholestasis in the postoperative patient. The patient may develop varying degrees of jaundice, dark urine, pruritus, and acholia. The prothrombin time may be prolonged because of vitamin K malabsorption associated with cholestasis. The pathophysiology underlying intrahepatic cholestasis involves processes that disturb bile flow at the microscopic level, either at the biliary membrane of the hepatocytes or at the level of the fine cholangiolar ductules (21). The nonspecific nature of histologic findings (i.e., canalicular bile plugs and bile staining) makes liver biopsy rarely useful in precisely identifying the cause of postoperative intrahepatic cholestasis. Liver biopsy, however, may be helpful in excluding the presence of underlying liver disease before the surgical procedure (see subsequent text). The most important clinical aspect when diagnosing postoperative cholestasis is to clearly ascertain the absence of mechanical biliary obstruction. Once the patency of the macroscopic biliary tree has been established, the clinician must consider the various causes of intrahepatic cholestasis. A broad number of liver disorders can occasionally present with a cholestatic pattern, including therapeutic drug–induced hepatic injury, infections, and cholestatic variants of

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viral hepatitis.

Therapeutic Drug–Induced Hepatic Injury Several pharmacologic agents frequently utilized in the perioperative period have the potential to cause liver injury. These include excessive use of acetaminophen and idiosyncratic hepatotoxic reactions to many antibiotics, anticonvulsants, and cardiovascular agents. Some commonly used agents with potential for hepatotoxicity include sulfas, penicillin derivatives, nitrofurantoin, phenytoin, amiodarone, statins, metronidazole, and fluconazole. Although acetaminophen administered in therapeutic doses is not hepatotoxic, liver injury may develop with routine doses in patients who regularly consume alcohol and/or have endured prolonged fasting, which deplete glutathione reserves (22). These individuals may develop elevated postoperative aminotransferase levels as a result of inadvertent acetaminophen overdosing, or as a result of the preceding factors that enhance acetaminophen hepatotoxicity. A detailed review of drug-induced hepatotoxicity can be found elsewhere in this textbook (see Chapters 33 and 34). Because of the large number of drugs with the potential to cause postoperative hepatic dysfunction, a careful history and review of the records documenting the agents used before, during, and after the surgical procedure is a key element of the investigation of postoperative liver injury. In general, drugs that the patient had been taking for more than 1 year preoperatively are unlikely to be involved in postoperative hepatotoxicity. Drug-induced liver injury generally develops within a few weeks and up to 12 months of exposure to the offending agent (1,2,3). Consequently, very early postoperative jaundice or liver biochemical abnormalities are unlikely to be related to drugs (with the possible exception of acetaminophen overdose). In contrast, hepatic dysfunction developing 2 to 3 weeks after surgery, or after initiation of new pharmacologic therapy, should be considered suspicious of druginduced liver injury. The biochemical and histologic patterns of druginduced liver injury encompass the broad spectrum of hepatic pathology. The cause–effect relation between a suspected agent and postoperative liver damage should be ascertained by assessing the temporal sequence of events and excluding other types of postoperative liver dysfunction, such as hepatic ischemia, viral hepatitis, and the cholestatic disorders outlined earlier. Liver biopsy is occasionally necessary to exclude other P.701 etiologies, but more often, there are no histologic features that are diagnostic of drug-induced liver disease.

Hepatitis and Cholestasis Associated with Anesthetic Agents General anesthesia is a well-known cause of postoperative jaundice.

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Careful review of the anesthetic record is important when determining the etiology of postoperative hepatic dysfunction. Certain anesthetic agents, sustained decrease in systolic blood pressure with subsequent reperfusion, and the need for cardiopulmonary bypass can all lead to severe liver injury (23,24,25). The most common manifestation, however, is transient hepatic dysfunction resulting from a reduction in splanchnic arterial blood flow during general anesthesia (25). Often, this is not correlated to a dramatic change in systolic blood pressure on the anesthetic record. In patients with portal hypertension, intraoperative hemodynamic changes can be of greater consequence. In cirrhosis, there is frequently reduced portal venous flow, and the hepatic artery is the primary source of inflow to the liver (5). In cases of true ischemic injury, aminotransferase levels can be elevated up to 100 times the normal value, along with significant elevations in lactate dehydrogenase (LDH) levels within the first few days. Alkaline phosphatase levels increase minimally (26). If the injury is severe, patients can further develop subfulminant or fulminant hepatic failure. In general, the liver blood biochemical test results return to normal within a week, although bilirubin may take longer to normalize. Liver biopsy can be useful to rule out underlying liver disease. Centrilobular (zone 3) hepatocellular necrosis is generally found and congestion is observed when cardiac failure has had a role in the ischemic injury. In general, a liver biopsy is not necessary to confirm the presence of postoperative ischemic hepatic injury (27,28). Certain volatile anesthetic agents have been implicated in the development of hepatitis. The most well-known instance is that of halothane and its metabolites (29,30,31). Halothane-associated hepatitis is estimated to occur in 1 of 10,000 halothane doses (32). Although hepatitis has been reported to occur after a single administration of anesthetic, the more common history involves multiple exposures. As the number of exposures increases, the severity of the hepatitis worsens. Some lethal reports have involved exposure intervals of less than 3 months. Patients at risk are often obese, older than 30 years, and of female gender (1,33). The two mechanisms thought to be involved are direct hepatic toxicity and the production of immunogenic protein complexes. All volatile anesthetic agents undergo some degree of biotransformation by the hepatic cytochrome P-450 system. The triacetyl chloride produced is the most troublesome because it binds covalently to hepatic macromolecules (34,35). Although this metabolite can lead to direct hepatocyte injury by itself, the more significant action of this protein immunocomplex is its initiation of the inflammatory response. Activation of the inflammatory cascade leads to amplification of the reaction and sensitization (36). Therefore, there is more severe

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reaction with each added exposure. Although elevation of liver blood biochemistries can be seen early after the exposure, symptoms can manifest as late as 2 to 3 weeks after administration. With each subsequent exposure, symptoms may present earlier. Patients can develop fever, nausea, vomiting, and rash followed by jaundice. They may also complain of arthralgias and right upper quadrant pain and have hepatomegaly on physical examination. Laboratory evaluation reveals significant elevation of liver biochemical test results depending on the severity. In mild to moderate cases, aminotransferase levels will be slightly elevated. However, in severe episodes, aminotransferase levels can be up to ten times the normal value, with significant elevation of LDH and serum bilirubin levels and decrease in concentration of coagulation factors. Usually, the liver function returns to normal within the first few weeks. However, progressive liver failure can occur, and mortality rates of up to 60% have been reported (1). Histology varies among reports (29,37). In moderate cases, pathology reveals centrilobular necrosis, with intense mononuclear infiltrate. In more severe cases, massive hepatic necrosis can be observed. Often, there is eosinophilia, supporting a role for an immune response. Although these changes are usually transient, chronic hepatitis with piecemeal necrosis has been seen on liver biopsy specimens as late as 10 months after exposure (38). Other halogenated agents used for anesthesia include enflurane, methoxyflurane, sevoflurane, isoflurane, and desflurane. Of these, enflurane and methoxyflurane have been more frequently reported to cause drug-induced hepatitis (39). The likelihood of developing a reaction is associated with the rate of biotransformation of each drug. Halothane, with a rate of 20%, is more likely to cause hepatitis than enflurane, sevoflurane, isoflurane, or desflurane, with rates of 2.5%, 1%, 0.2%, and 0.02%, respectively (35). Scattered reports do exist in the literature for each of these agents, although they remain quite rare. Because there is cross-reactivity among these agents, exposure to any of them may lead to reactions to the rest. For instance, all the reports involving desflurane or isoflurane document prior exposure to halothane or enflurane. Treatment consists of withdrawal of the causative agent and supportive care. If hepatic failure develops, urgent liver transplantation may be required. Once a P.702 patient has had documented liver dysfunction from any of the halogenated anesthetics, it is recommended that their use be avoided on subsequent surgical procedures.

Postoperative Cholestasis Due to Infection Postoperative sepsis can be accompanied by abnormal liver biochemical

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test results. The total bilirubin level, including an increase in directreacting bilirubin, is often elevated to a range between a few milligrams per deciliter and sometimes greater than 20 mg/dL. Alkaline phosphatase and aminotransferase levels may also be abnormal, but generally to a lesser degree than those of bilirubin and in a nonspecific manner. Infections with anaerobes, aerobes, and gram-positive and gram-negative bacteria can lead to postoperative intrahepatic cholestasis. Pyelonephritis or urinary tract infection, appendicitis, cholecystitis, diverticulitis, or peritonitis in the postoperative patient can be associated with the development of cholestatic reactions. Infection-related cholestasis should be suspected in the presence of fever, leukocytosis, positive blood cultures, or evidence indicating an active infectious process (e.g., abscess on imaging studies and/or purulent drainages). The diagnosis of infection-related hepatic dysfunction should also be considered when the etiology of postoperative jaundice remains obscure and other causes of jaundice have been appropriately ruled out. Liver biopsy is not required for the diagnosis because of the lack of specific histopathologic features. If performed, however, hepatic histology often reveals ductular proliferation, polymorphonuclear-based cholangitis, and canalicular cholestasis. The management of postoperative jaundice associated with infection should focus on the treatment and control of the specific infection.

Viral Hepatitis Currently, transfusion of blood products carries a very small risk of transmitting hepatitis B or C viruses (40). Consequently, acute viral hepatitis has become a rare cause of postoperative jaundice. Postoperative acute viral hepatitis is likely to have been acquired before the surgical procedure, and without knowing this the patient may have undergone the surgery during the incubation period of the hepatitis virus. The elevation of ALT and AST levels may be detected at any time after surgery, depending on the timing of the infection and the virus incubation period. The characteristic biochemical profile is that of a marked elevation of the content of aminotransferases, often to greater than ten times the upper normal level. In severe cases, bilirubin level also increases and coagulopathy may develop. The serologic diagnosis, management and prognosis of acute viral hepatitis A, B, or C, is reviewed in detail elsewhere in this textbook (see Chapter 26). Other viruses that may cause hepatitis (e.g., EpsteinBarr, cytomegalovirus, herpes simplex) are even less common in the postoperative setting, but they should be kept in mind when dealing with immunosuppressed patients (41).

Benign Postoperative Cholestasis A frank cholestatic syndrome may develop postoperatively with

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prominent elevation in alkaline phosphatase levels and mild to moderate hyperbilirubinemia. The abnormalities typically develop during the first two postoperative weeks and occasionally may take weeks or months to resolve. The diagnosis of benign postoperative cholestasis should be considered in patients after major or complicated abdominal or thoracic surgery. Benign postoperative cholestasis may also occur in patients who receive large amounts of transfusions, develop a postoperative infectious process, or undergo surgery in the setting of burns or trauma. The pathogenesis of benign postoperative cholestasis is not fully understood but it is generally considered a multifactorial process. Factors such as excessive bilirubin production from hematomas or transfusions, infections, prolonged complex surgery, hypoxemia, and decreased hepatic perfusion may play a role in the development of benign postoperative cholestasis. At the cellular level, cytokines resulting from the systemic inflammatory response may interfere with canalicular bile transport and lead to cholestasis (21). Because there is no specific test to confirm benign postoperative cholestasis, this diagnosis is based on the exclusion of other causes of jaundice, most specifically obstruction. Basic viral hepatitis serologies are necessary if there is prominent ALT level elevation (greater than five to ten times of the upper normal limit) associated with cholestasis. Surgical and anesthesia records may reveal prolonged arterial hypotension, intraoperative heart failure, or sustained hypoxemia in patients who develop benign postoperative cholestasis. Liver biopsy is not required to establish the diagnosis but it may be considered when atypical features are present, or in patients suspected of having underlying cholestatic liver disease not identified preoperatively. If a liver biopsy is performed, histologic findings supportive of benign postoperative cholestasis include canalicular bile plugs and prominent bile staining, especially in the centrilobular areas; foamy degeneration of hepatocytes; and modest focal steatosis (42). Less frequently, serum bilirubin level may peak between 10 and 40 mg/dL. In these instances, repeated assessment of the biliary tract with ultrasonography is necessary to exclude intercurrent biliary obstruction. The prognosis of benign postoperative cholestasis is variable and depends less on the cholestatic reaction than on the P.703 overall condition of the patient and severity of associated comorbidities. Management is directed toward the reversal of factors leading to impaired hepatic function and include appropriate intravascular volume support, correction of anemia, antibiotic therapy for infections, and replacement of potentially cholestatic therapeutic drugs by agents metabolized and excreted by extrahepatic sites. There are no data supporting the routine use of choleretics such as ursodeoxycholic acid to treat or expedite the resolution of benign

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postoperative cholestasis. When the cholestasis is prolonged, the associated postoperative decreased enteral nutrition and use of antibiotics may cause vitamin K deficiency and lead to coagulopathy. Parenteral administration of vitamin K is useful in correcting the prolonged prothrombin time in this setting. Failure of vitamin K to correct the prothrombin time should raise the suspicion of underlying parenchymal liver disease.

Hepatic Ischemia Ischemic injury to the liver is a relatively common cause of postoperative abnormal liver function test results (26,27,28). There are multiple mechanisms by which the liver may experience perioperative ischemic damage, including arterial hypotension leading to diminished splanchnic arterial perfusion and portal vein blood flow, effect of anesthetic agents, right or left cardiac failure, severe hypoxemia, and even ischemic-reperfusion injury. Moreover, the patient with cirrhosis is especially susceptible to intraoperative ischemia because of the increased dependency of the cirrhotic liver on hepatic artery blood flow. Whether patients with NAFLD or NASH are more prone to perioperative hepatic ischemia is not known. A recent report on bariatric surgery in patients with NASH-related cirrhosis did not find increased postoperative ischemic complications (4). Jaundice may occur in severe cases of hepatic ischemia but more often the injury is characterized by an early and rapid rise of the levels of both aminotransferases within 1 to 10 days of the surgical procedure. The extent of the elevation varies considerably and may range from 2 to greater than 100 times the upper normal limit of AST and ALT concentration. Once the hepatic hypoperfusion is corrected, ALT and AST levels also generally begin to decline at a fast rate. Alkaline phosphatase level is generally normal or only mildly elevated. LDH level is also markedly elevated in hepatic ischemia. It is important to consider that in postoperative trauma patients, AST, ALT, and LDH may not necessarily reflect hepatic injury but these enzymes may also originate from extensive muscle injury or rhabdomyolysis. In severe cases of hepatic ischemia, elements of liver failure may develop, such as coagulopathy, hypoglycemia, and hepatic encephalopathy. However, hepatic ischemia is an uncommon etiology of acute liver failure (43). The diagnosis of postoperative hepatic ischemia is based on the clinical picture, the time course and pattern of liver biochemical abnormalities, and the identification of perioperative conditions leading to hepatic ischemia. Therefore, a history of intra- or postoperative myocardial infarction, shock, pulmonary embolism, significant hypoxemia, or arterial hypotension of any cause will often be found associated with postoperative ischemic hepatic dysfunction. A review of the intraoperative anesthesia records may reveal periods of sustained

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arterial hypotension. If the surgical procedure consisted of a cholecystectomy or surgery near the porta hepatis, or involved an anatomic hepatic resection, the possibility of inadvertent ligation of the hepatic artery or a main branch must be considered. Imaging studies (e.g., magnetic resonance imaging [MRI], multiphase computed tomography [CT], and Doppler ultrasonography) may show areas consistent with infarction or absent hepatic vascular flow. Given the predominant elevation of levels of aminotransferases, the differential diagnosis must include viral hepatitides and drug-induced hepatitis. However, the increase in the levels of these liver enzymes generally occurs later in the postoperative period, and the rise and decline in their concentration are more gradual than the relatively rapid changes observed in hepatic ischemia. Liver biopsy is not necessary to establish the diagnosis of ischemic hepatic injury except when the clinical picture is obscure. Histologic findings of noninflammatory centrizonal hepatocellular necrosis support the diagnosis of postoperative hepatic dysfunction due to ischemic injury. Management of postoperative hepatic dysfunction due to ischemic injury consists of restoration of hepatic perfusion by appropriate support of the intravascular blood volume. Hypoxemia should be corrected and the underlying complications (i.e., hemorrhage, cardiac failure, pulmonary embolism, and sepsis) treated accordingly. The outcome of hepatic ischemia is generally favorable but the patient's prognosis is determined by the severity of the associated comorbid conditions.

Postoperative Jaundice due to Increased Bilirubin Load Mild degrees of unconjugated (indirect-reacting) bilirubin are not uncommonly observed in postoperative patients. Although the liver has a large capacity to take up, conjugate, and excrete bilirubin, under certain circumstances, the amount of bilirubin produced may exceed the capacity of hepatic removal. Therefore, P.704 resorption of large hematomas, large volume transfusion, and underlying hemolytic conditions (e.g., glucose-6-phosphate dehydrogenase [G6PD] deficiency, sickle cell disease, autoimmune hemolytic anemia, and thalassemias) may result in excessive production of bilirubin. In other patients, increased intravascular hemolysis is caused by therapeutic drugs, mechanical heart valves, or infections. The diagnosis should be suspected when mild to moderate hyperbilirubinemia (2 to 6 mg/dL) develops during the first two postoperative weeks. Because of the considerable content of AST and LDH in red blood cells, the hyperbilirubinemia may be accompanied by modest elevation in the levels of AST and/or LDH. ALT level, alkaline

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phosphatase level, prothrombin time, and serum albumin level should be normal or only minimally altered. Deformed red blood cells in the peripheral smear, low circulating haptoglobin levels, and increased reticulocyte count point to hemolysis as the cause of postoperative jaundice. Frequently, patients have multiple factors that may cause postoperative jaundice, including hepatic ischemia, underlying liver disease, infection, and impaired renal function. In this multifactorial setting, the effect of bilirubin overproduction is compounded by hepatic dysfunction. Serum bilirubin levels may reach higher values, have a substantial component of conjugated bilirubin, and may be accompanied by significant elevation in the level of ALT and coagulopathy. Management consists of close monitoring of the liver biochemical abnormalities while correcting the reversible factors outlined earlier.

Postoperative Jaundice Associated with Parenteral Nutrition Total parenteral nutrition (TPN)-induced liver dysfunction is not uncommon; however, it is rarely the primary cause of postoperative jaundice. Other etiologies of liver dysfunction must be ruled out before this diagnosis. In fact, the indication for TPN is often associated with significant comorbidities that may lead to postoperative hepatic dysfunction. Discerning the length of time for which the patient has received TPN is another significant factor. Chronic TPN administration, usually for more than 3 months, may lead to the development of liver disease. Bacterial or fungal sepsis is associated with both cholestasis and TPN administration. Bacterial overgrowth from bowel disease and the presence of indwelling catheters predispose patients to systemic infection. Conversion to enteral nutrition as early as possible should be the primary goal. Within the first 2 weeks of TPN administration, mild elevation of liver biochemical test results is frequently observed. Benign steatosis is the most common finding on biopsy and is often the result of excessive caloric intake, particularly from dextrose (44). Rarely, patients may present with right upper quadrant pain and hepatomegaly (45). The initial step in evaluating abnormal liver biochemical test results in a postoperative patient on TPN should include an assessment of the percentage of calories from carbohydrates and fats and adjustment of the formulation as necessary. The mechanism for TPN-induced steatosis is multifactorial. Hormonal derangements and nutritional deficiencies that promote production of fat and impair its release from the hepatocyte are involved. Although controversial, several reports support the use of oral lecithin

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supplements and choline-supplemented TPN to ameliorate steatosis (45,46). Benign steatosis is associated with a moderate increase in aminotransferase levels along with mild increases in alkaline phosphatase and serum bilirubin levels. These laboratory abnormalities are nonspecific and are present in other etiologies of postoperative liver dysfunction. Therefore, liver biopsy may be helpful when the diagnosis is uncertain. Histology can range from isolated periportal fat to panlobular involvement in severe cases (47,48). The laboratory and histologic changes generally correlate with length of TPN administration. Withdrawal of TPN often leads to complete resolution. If a postoperative patient is TPN dependent, however, manipulation of the TPN formula or cycling over 10 to 12 hours each day may allow for reduction or slowing of the process. As TPN administration is prolonged, steatohepatitis with eventual fibrosis may develop (49). Withdrawal of TPN at this point may or may not lead to improvement in fibrosis. However, many of these patients have intestinal failure and are TPN dependent. These patients may ultimately require combined liver–intestinal transplantation. TPN-induced cholestasis is a less common finding in short-term courses of nutritional support. If it does occur, it may present as early as 3 weeks after starting therapy. In children, cholestasis is the most common presentation and is related to incomplete development of biliary secretory mechanisms in premature infants (50). In adults, cholestasis manifests itself as a slow and progressive elevation of alkaline phosphatase and bilirubin levels. In these patients, early use of metronidazole to prevent bacterial overgrowth and ursodeoxycholic acid to induce bile flow and promote a more hydrophilic bile may help improve the hepatic dysfunction (51,52). Lastly, TPN may directly affect the biliary tract. Patients who are unable to use their gastrointestinal system develop akinesis of the gallbladder with biliary stasis and ultimately develop sludge. Length of TPN therapy correlates with gallbladder dysfunction. After 6 weeks, most patients have evidence of gallbladder sludge on ultrasound (45,53). The presence of sludge promotes the production of biliary stones, P.705 thereby leading to the complications associated with cholelithiasis. Regardless of sludge or stones, TPN may play a role in acalculous cholecystitis. This diagnosis is usually made in critically ill patients, with multiple factors contributing to its development. Because the diagnosis is difficult to make and the morbidity is significant, prevention is the primary goal. Early enteral feeding or administration of cholecystokinin to stimulate gallbladder activity appears beneficial. A calculous cholecystitis can also occur in chronically ill patients who have been TPN dependent for longer than 3 months. The patients may need a cholecystectomy if medically stable or otherwise drainage by a percutaneously placed cholecystostomy tube (54).

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Postoperative Jaundice following Liver Transplantation With current liver allocation based on the MELD score, many patients undergoing liver transplantation have prolonged jaundice in the posttransplantation period. The differential diagnosis for postoperative onset or worsening of jaundice after liver transplantation is broad and include primary allograft dysfunction, ischemic injury, intraoperative transfusions, therapeutic drug hepatotoxicity, biliary and/or vascular complications, hematoma reabsorption, acute cellular rejection, ABO mismatch, disease recurrence, and bacterial, fungal, and viral infections. The evaluation and management of postoperative liver allograft dysfunction is reviewed in detail elsewhere in this book (see Chapters 55 and 56).

Annotated References Befeler A, Palmer D, Hoffman M, et al. The safety of intraabdominal surgery in patients with cirrhosis. Arch Surg 2005;140:650–654. This 10-year study identified a MELD score of 14 or greater as a predictor of very high risk for abdominal surgery. The authors suggest that it should replace the class C Child-Turcotte-Pugh patients and several patients with hepatic and multiorgan failure. Faust T, Reddy KR. Postoperative jaundice. Clin Liver Dis 2004;8:151–166. A comprehensive review of causes and management of postoperative jaundice. Keegan M, Plevak D. Preoperative assessment of the patient with liver disease. Am J Gastroenterol 2005;100(9):2116–2127. A thorough review of the preoperative factors that may lead to postoperative jaundice and hepatocellular dysfunction, with special emphasis on preexisting liver disease and effect of anesthetics. Northup P, Wanamaker R, Lee V, et al. Model for End-stage Liver Disease (MELD) predicts nontransplant surgical mortality in patients with cirrhosis Ann Surg 2005;242:244–251. A direct correlation between the objective scale of disease-severity MELD and postoperative mortality in patients with cirrhosis undergoing nontransplantation surgery.

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Seeto R, Fenn B, Rockey D. Ischemic hepatitis: clinical presentation and pathogenesis. Am J Med 2000;109:109–113. A detailed analysis of the causes and manifestations of hepatic ischemia.

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4. Dallal R, Mattar S, Lord J, et al. Results of laparoscopic gastric bypass in patients with cirrhosis. Obes Surg 2004;14:47–53.

5. Ziser A, Plevak DJ, Wieser RH, et al. Morbidity and mortality in cirrhotic patients undergoing anesthesia and surgery. Anesthesiology 1999;90(1):42–53.

6. Keegan M, Plevak D. Preoperative assessment of the patient with liver disease. Am J Gastroenterol 2005;100:2116–2127.

7. Befeler A, Palmer D, Hoffman M, et al. The safety of intraabdominal surgery in patients with cirrhosis. Arch Surg 2005;140:650–654.

8. Northup P, Wanamaker R, Lee V, et al. Model for end stage liver disease (MELD) predicts nontransplant surgical mortality in patients with cirrhosis. Ann Surg 2005;242:244–251.

9. Mijnhout GS, Klinkenberg EC, Lychlama G, et al. Sepsis and elevated liver enzymes in a patient with inflammatory bowel disease: think of portal vein thrombosis. Dig Liver Dis 2004;36:296–300.

10. Shirota T, Sasjima K. Hyperbilirubinemia after esophagectomy.

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12. Sicklick JK, Camp MS, Lillemoe KD, et al. Surgical management of bile duct injuries sustained during laparoscopic cholecystectomy. Ann Surg 2005;241:786–795.

13. Himal HS. Common bile duct stones: the role of perioperative, intraoperative and postoperative ERCP. Semin Laparosc Surg 2000;7:237–245.

14. Contractor QQ, Dubian MK, Boujemla M, et al. Endoscopic therapy after laparoscopic cholecystectomy. J Clin Gastroenterol 2001;33:218–221.

15. Costamagna G, Pandolfi M, Mutignani M, et al. Long-term results of endoscopic management of postoperative bile duct strictures with increasing numbers of stents. Gastrointest Endosc 2001;54:162–168.

16. Lillemoe KD, Melton GB, Cameron JL, et al. Postoperative bile duct strictures: management and outcome in the 1990s. Ann Surg 2000;232:430–441.

17. Belghiti J. Arguments for a selective approach of preoperative portal vein embolization before major hepatic resection. J Hepatobiliary Pancreat Surg 2004;11(1):21–24.

18. Madoff DC, Abdalla EK, Vauthey JN. Portal vein embolization in preparation for major hepatic resection: evolution of a new standard of care. J Vasc Interv Radiol 2005;16:779–790.

19. Tsiotos GG, Mullany CJ, Zietlow S, et al. Abdominal complications following cardiac surgery. Am J Surg 1994;167:553– 557.

20. Burkey SH, Valentine RJ, Jackson MR, et al. Acute pancreatitis

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after abdominal vascular surgery. J Am Coll Surg 2000;191:373– 380.

21. Trauner M, Meier P, Boyer J. Molecular pathogenesis of cholestasis. N Engl J Med 1998;339:1217–1227.

22. Whitcomb D, Block G. Association of acetaminophen hepatotoxicity with fasting and ethanol. JAMA 1994;272:1845– 1850. P.706 23. Henrion J, Schapira M, Luwaert R, et al. Hypoxic hepatitis: clinical and hemodynamic study in 142 consecutive cases. Medicine 2003;82:392–406.

24. Hampton WW, Townsend MC, Schirmer WJ, et al. Effective hepatic blood flow during cardiopulmonary bypass. Arch Surg 1989;124:458–459.

25. McEvedy B, Shelly M, Park G. Anaesthesia and liver disease. Br J Hosp Med 1986;36:26–34.

26. Fuchs S, Bogomolski-Yahalom V, Paltiel O, et al. Ischemic hepatitis clinical and laboratory observation of 34 patients. J Clin Gastroenterol 1998;26:183–186.

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29. Benjamin S, Goodman Z, Ishak K, et al. The morphologic spectrum of halothane-induced hepatic injury: analysis of 77 cases. Hepatology 1985;5(6):1163–1171.

30. Ray D, Drummond G. Halothane hepatitis. Br J Anaesth 1991;67:84–99.

31. Dawson B, Adsen M, Deckerry M, et al. Hepatic function tests: postoperative changes with halothane or diethyl ether anesthesia.

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33. Farrell G, Prendergast D, Murray M. Halothane hepatitis, detection of a constitutional susceptibility factor. N Engl J Med 1985;313:1310–1314.

34. Kenna J, Satoh H, Christ D, et al. Metabolic basis for a drug hypersensitivity: antibodies in sera from patients with halothane hepatitis recognize liver neoantigens that contain the trifluoroacetyl group derived from halothane. J Pharmacol Exp Ther 1988;245:1103–1109.

35. Njoku D, Laster M, Gong D, et al. Biotransformation of halothane, enflurane, isoflurane, and desflurane to trifluoroacetylated liver proteins: association between protein acylation and hepatic injury. Anesth Analg 1997;84:173–178.

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37. Gall E. Report of the pathology panel: national halothane study. Anesthesiology 1968;29:233–248.

38. Kronborg I, Evans D, Mackay I, et al. Chronic hepatitis after successive halothane anesthetics. Digestion 1983;27(2):123–128.

39. Lewis J, Zimmerman H, Ishak K, et al. Enflurane hepatotoxicity. A clinicopathologic study of 24 cases. Ann Intern Med 1983;98(6):984–992.

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46. Buchman A, Ament M, Sohel M, et al. Choline deficiency causes reversible hepatic abnormalities in patients receiving parenteral nutrition: proof of human choline requirement: a placebo-controlled trial. JPEN J Parenter Enteral Nutr 2001;25:260–268.

47. Jacobson S, Ericsson JL, Obel AL. Histopathological and ultrastructural changes in the human liver during complete intravenous nutrition for seven months. Acta Chir Scand 1971;173:335–349.

48. Campos A, Oler A, Meguid M, et al. Liver biochemical and histological changes with graded amounts of total parenteral nutrition. Arch Surg 1990;125:447–450.

49. Cavicchi M, Beau P, Crenn P, et al. Prevalence of liver disease and contributing factors in patients receiving home parenteral nutrition for permanent intestinal failure. Ann Intern Med 2000;132:525–532.

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53. Messing B, Bories C, Kuntslinger F, et al. Does total parenteral nutrition induce gallbladder sludge formation and lithiasis? Gastroenterology 1993;84:1012–1019.

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Editors: Title:



Copyright ©2007 Lippincott Williams & Wilkins > Table of Contents > Volume I > Section V - Viral Hepatitis > Chapter 26 - The Hepatitis Viruses

Chapter 26 The Hepatitis Viruses Amany Zekry John G. Mchutchison

Key Concepts z

Hepatitis A virus is a ribonucleic acid (RNA) virus accounting for most cases of acute hepatitis. Seroprevalence rates in industrialized countries have been falling because of vaccination programs and improvements in socioeconomic conditions. As a result, an age-related shift in seroprevalence has taken place in which adults and elderly are presently more at risk of infection.

z

Hepatitis B virus (HBV) is a deoxyribonucleic acid (DNA) virus, with the highest prevalence rates of infection in Southeast Asia, China, and Africa. Most persons who acquire the infection before 5 years of age develop chronic hepatitis B infection. The natural course of chronic infection is variable. HBV-infected patients have an increased risk of developing hepatocellular carcinoma (HCC) compared to uninfected patients. A variety of therapies are available and approved, including conventional interferon (IFN), pegylated IFN, and nucleoside analogs such as lamivudine, adefovir dipivoxil, and entecavir. Treatment of HBV is, however, still limited by factors such as the development of drug resistance and the low efficacy of available therapies in eliminating covalently closed circular HBV DNA.

z

Hepatitis C virus (HCV) is an RNA virus, accounting for most patients with chronic hepatitis worldwide. Intravenous drug use is presently the primarily source of infection. The natural course of HCV infection, although slowly progressive usually, is variable. Pegylated IFN has been shown to be effective in permanently eradicating the virus in the setting of acute HCV infection. Presently, the combination of pegylated IFN-α and ribavirin is the standard therapy for chronic HCV infection and appears to cure approximately 50% of treated patients. Response and duration of treatment is dependent on the infecting viral genotype.

z

Hepatitis delta virus (HDV) relies on HBV for infectivity and persistence. Dual infection with HDV and HBV results in progressive liver disease and increased risk of HCC. IFN remains the only drug to

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have any therapeutic effect. z

Hepatitis E virus (HEV) is an RNA virus that causes an acute selflimiting hepatitis with no chronic sequelae. Acute HEV infection, however, results in a high mortality rate among pregnant women, particularly during the third trimester.

z

Hepatitis G virus (HGV) is a recently identified RNA virus. A firm and direct association with liver pathology is still lacking, and it is unclear whether HGV is hepatotropic. Coinfection with HGV and human immunodeficiency virus (HIV) has been shown to improve mortality and morbidity for the HIV-infected individuals and slows progression to acquired immunodeficiency syndrome.

z

Herpesviruses are a family of large enveloped DNA viruses. Infection with herpesviruses occurs worldwide. Herpesvirus infection is occasionally associated with hepatitis. Clinically overt severe and fulminant hepatitis may, however, occur, usually in immunocompromised hosts.

P.710 There are six identified human hepatitis viruses; these are hepatitis A virus (HAV), hepatitis B virus (HBV), hepatitis C virus (HCV), hepatitis delta virus (HDV), hepatitis E virus (HEV), and hepatitis G virus (HGV). These viruses have distinctive biologic and clinical properties that have been unraveled over the years. In this regard, substantial advances have been made in our understanding of the genomic structure, life cycle, natural history, and pathogenesis of most of these viruses. We have also been able to exploit our increased knowledge to develop effective therapeutic strategies for each of these viruses, and several advances have been made in this regard (Table 26.1). Despite these ongoing efforts, viral hepatitis continues to represent a major public health challenge worldwide. Also, chronic hepatitis remains a disease with significant morbidity and mortality, and response to current therapy is far from optimal. This chapter introduces each of these viruses, giving an overview of the epidemiologic aspect, molecular aspect, natural history, immunopathogenesis, and treatment aspect of each. In addition, we discuss briefly the herpesviruses, which are not primarily hepatotropic, but are occasionally associated with hepatitis.

Hepatitis A Virus Epidemiology HAV infection is a major cause of acute hepatitis and liver failure throughout the world. HAV infection is particularly common in developing countries of Africa, Asia, and Latin America, where seroprevalence rates approach 100% (1). In these countries, most infections occur by 5 years of age. By contrast, seroprevalence rates in industrialized countries have been falling because of improvements in socioeconomic conditions. As a result, an age-related shift in seroprevalence has taken place, so that adults and

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the elderly are at a greater risk of acquiring an HAV infection. Therefore, about one third of the US population has serologic evidence of previous HAV infection, with prevalence rates ranging from 9% among children to 75% among persons aged 70 years or older (1). HAV is primarily transmitted enterically (fecal–oral route), typically by ingestion of contaminated food or water and through person-to-person contact within the household (2). Crowded or unsanitary conditions are commonly implicated. Although it is rare, parenteral transmission due to the use of contaminated blood products is possible, while vertical transmission is extremely uncommon (2,3). Risk groups for HAV infection include travelers to endemic areas, military personnel, day care workers, and the institutionalized patients. Also, homosexuals with multiple sexual partners and intravenous drug users are at higher risk for HAV acquisition (2).

Table 26.1. Recent Developments in Therapy for Viral Hepatitis

HAV Effective vaccines are available; however, HAV remains a major cause of acute hepatitis worldwide HBV Effective vaccines have reduced HBV prevalence in many countries Pegylated interferon monotherapy has recently been shown to have significant virologic efficacy in a trial comparing this treatment alone to combination of pegylated interferon and lamivudine or lamivudine alone in largely Asian HBeAg-positive patients In patients awaiting liver transplantation, lamivudine has been shown to suppress HBV DNA, stabilize the progression of liver disease, delay the need for liver transplantation, and improve survival among these patients Adefovir dipivoxil suppresses HBV DNA in patients with lamivudine resistance In HBeAg-negative patients, the virologic response achieved by a 12-mo course of adefovir is not sustained once treatment is ceased Entecavir effectively suppresses HBV DNA in HBeAg-positive and HBeAg-negative patients, as well as in those with lamivudine resistance HCV Pegylated interferon monotherapy is effective in achieving viral clearance in acutely infected patients Combination pegylated interferon and ribavirin is presently the treatment of choice for chronic HCV infection Combination pegylated interferon/ribavirin is well tolerated in HCV/HIV coinfected patient and results in acceptable virologic response rates

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Combination pegylated interferon/ribavirin is presently used to individually treat significant recurrent HCV infection after liver transplantation Ongoing research into novel therapeutic agents and vaccine development is proceeding rapidly HDV High-dose prolonged interferon monotherapy remains the most effective therapeutic option, although side effects may limit therapy

HAV, hepatitis A virus; HBV, hepatitis B virus; HBeAg, hepatitis B e-antigen; DNA, deoxyribonucleic acid; HCV, hepatitis C virus; HDV, hepatitis delta virus; HIV, human immunodeficiency virus.

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The Hepatitis a Virus Genome and Proteins HAV is a ribonucleic acid (RNA) virus, a member of the Picornaviridae family. HAV is a nonenveloped icosahedral particle 27 to 32 nm in diameter (4). The infectious particle consists of a capsid protein and the RNA genome. The HAV genome is a positive single-stranded RNA approximately 7.5 kb long (Fig. 26.1). The genome is defined by three distinct regions: The 5′ noncoding region (NCR) of approximately 735 nucleotides contains an internal ribosomal entry site (IRES). As with other picornaviruses, the 5′ end of the genome does not have a cap structure but instead is covalently linked to the viral protein VPg, involved in the initiation of RNA synthesis. The 5′ NCR appears to be the most conserved region of the genome. Some mutations in the 5′ NCR region enhance growth of HAV in cell culture but do not appear to have a major role in determining HAV virulence. The 5′ NCR is followed by a single open reading frame (ORF) for a large polyprotein containing P1, P2, and P3 regions. The P1 region encodes the capsid proteins VP1 to VP4. Mature capsid proteins are the predominant form in virions. VP1 and VP3 form a single, dominant epitope on the viral capsid and elicit a neutralizing antibody response. VP4 harbors a potential myristoylation site and is essential for virion formation. The P2 and P3 regions encode the nonstructural proteins associated with viral replication. Among these proteins, 3C is recognized as the sole protease for HAV, while protein 3D has RNA-dependent RNA polymerase activities. Precursor polypeptides include VP0, which is a VP4/VP2 fusion protein. Finally, the 3′ NCR is about 63 nucleotides in length, terminating in a poly-A tract.

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▪ Figure 26.1 The hepatitis A virus (HAV) genome—the HAV genome is a linear, positive-sense, single-stranded ribonucleic acid (RNA) approximately 7.5 kb in length. A VPg protein is covalently attached to the 5′ end of the genome and a poly-A tail at the 3′ end. The genome codes for a single polyprotein of approximately 2,235 amino acids. The polyprotein is divided into three main functional domains: P1, P2, and P3. P1 encodes the viral capsid proteins while P2 and P3 code for the nonstructural proteins including RNA helicase, protease, and RNA polymerase. 5′ NCR, 5′ noncoding region.

Hepatitis a Virus Life Cycle It is not clear how the HAV reaches the hepatocytes. The virus is taken up by a mucin-like class I integral membrane glycoprotein, presumed to be the receptor for HAV (5). However, it is not known how the virus reaches the cytoplasm, the site of viral replication. Replication of the genome occurs by a mechanism involving the RNA-dependent RNA polymerase. In this regard, virus-encoded proteins replicate the RNA genome through a negative-strand intermediate. A relatively large number of plus strands are transcribed from the minus strand. The new plus strand may enter another cycle of replication or serve as a template for polyprotein translation. For translation, cis-acting picornaviral IRES is thought to interact with transacting cellular factors, so that 40S ribosomal subunits begin translation at the correct initiation codon. The HAV has two initiation codons that can function independently (6). The single ORF of the picornaviruses is translated into one long precursor polypeptide (Fig. 26.1), which is processed by a cascade of proteolytic cleavage to yield the mature viral proteins (7). 3C protein is the primary cleavage enzyme. The primary cleavage takes place cotranslationally at the C-terminus of the VP1/2A precursor. Subsequently, 3C secondarily catalyzes VP2/VP3 and VP3/VP1 to

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produce 14S pentamers containing VP0, VP3, and VP1/2A. VP1 is released from 2A by cellular proteases. Maturation P.712 cleavage involves the processing of VP0 to release VP4 and VP2. Transacting host factors for HAV may play a role in the translation process. The pentamers assemble to form empty capsids (procapsids) or incorporate virion RNA to form provirions. The mechanisms by which the virus is released and secreted from the infected cell have not been entirely elucidated as yet.

Natural History of Hepatitis a Virus Infection Humans are the principal host of HAV. Most infections (70%) in children younger than 6 years are asymptomatic, in contrast to a frequently symptomatic course in adults. With increasing age, infections become more and more clinically apparent, and by adolescence, more than 80% of patients develop jaundice (2,8). After acute HAV infection, recovery with lifelong immunity is the norm. Uncommon clinical features of acute HAV infection include the development of cholestatic hepatitis or, less commonly, relapsing hepatitis. In each of these situations, however, the prognosis is good. Fulminant hepatitis develops in less than 1% of acutely infected HAV cases and is more common among infected adults. Therefore, elderly patients and persons with chronic liver disease are at increased risk of progressing to fulminant liver failure (9). Although spontaneous recovery usually occurs, liver transplantation may be necessary for those patients who fail to improve.

Immunopathogenesis of Hepatitis a Virus Infection HAV is unlikely to be a cytopathic virus, and the host immune response to HAV is believed to be responsible for the observed necroinflammatory lesion. In support of this, increased expression of CD4 and CD8 + T-cell receptors has been demonstrated at inflammatory sites in the livers of acutely infected patients (10). Moreover, HAV-specific CD8 + T cells with cytotoxic activities have been isolated from these affected livers (11). In the acute phase of the illness, a dominant immunoglobulin M (IgM) and IgG immune response against VP1 has been identified. Similarly, antibodies against VP3 and VP0 develop during the late convalescence phase. Circulating antibodies, therefore, seem to limit the viremic phase. Nonsecretory IgG antibody to HAV then persists in the serum after infection, providing lifelong immunity.

Treatment of Hepatitis a Virus Infection No specific therapy is required for acute HAV, and antiviral therapy is not available. The most effective means of controlling HAV are preventive measures relying on strict hygiene and vaccination programs. Available vaccines are safe, highly immunogenetic, and induce long-lasting (>20 years) protection against HAV. Routine vaccination is currently recommended for high-risk groups aged 2 years or older. These groups

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include young children in endemic areas and travelers to these areas, homosexual men, intravenous drug users, and patients with chronic liver disease (12).

Hepatitis B Virus Epidemiology The epidemiology of HBV infection varies greatly worldwide. The HBV carrier rate ranges from 8% to 20% in highly endemic areas such as Southeast Asia, China, and Africa to less than 2% in North America, western Europe, and Australia (13). In highly endemic areas, spread of HBV infection is mostly the result of maternal–infant transmission (vertical), while the use of reusable syringes and injectable drugs, and sexual spread, are also important. In contrast, sexual activity and injectable drug use account for most HBV cases in low endemic areas. However, even in low endemic areas, HBV infection is present in a substantial number of immigrants from highly endemic areas. Other less common risk factors for HBV transmission include occupational exposure, hemodialysis, acupuncture, household contact, and the receipt of infected organs or blood products (13). In several countries, effective strategies have been implemented to reduce the risk of HBV transmission. These include public education, routine infant and adolescent vaccination, HBV screening of pregnant women, and administration of postexposure prophylaxis to infants of infected women (14). In Taiwan, the HBV vaccination program in newborns has dramatically decreased both the prevalence of hepatitis B infection and the incidence of hepatocellular carcinoma (HCC) in this population (15).

Hepatitis B Virus Genome and Proteins HBV is a member of the Hepadnaviridae family (hepatotrophic deoxyribonucleic acid [DNA] viruses). The mature HBV virion, also known as the Dane particle, is 42 nm in diameter, consisting of an outer lipoprotein layer that encodes the viral envelope proteins, the hepatitis B surface antigen (HBsAg), and surrounds a nucleocapsid core, the hepatitis B core antigen (HBcAg) (16). The nucleocapsid contains the viral genome and the viral polymerase. In addition to the mature virions, HBV-infected serum contains two other distinct subviral particles that are either spherical P.713 or filamentous in shape and are approximately 20 nm in width. Subviral particles reach a 10,000-fold higher concentration than virions in the serum. They consist of an envelope glycoprotein and host-derived lipids. The precise biologic significance of this massive overproduction of empty envelopes is unknown; however, it has been speculated that they serve as decoys for the host's immune system. The HBV genome (Fig. 26.2) is a partially relaxed double-stranded circular DNA of approximately 3,200 base pairs (bp) and encodes four partly overlapping ORFs: The envelope or the surface gene, the core gene, the

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polymerase, and the X gene (HBx). The 5′ end of the complete minus DNA strand is covalently linked to the polymerase-coding gene, while the 5′ end of the plus strand is linked with a short piece of capped RNA. The termini of the 5′ end of the minus and plus strands map to the regions of short (11 to 12 nucleotides) direct repeats (DRs) in viral DNA, known as DR1 and DR2. These repeat regions are involved in priming the synthesis of their respective DNA strands. The viral envelope consists of cellular phospholipids and three virally encoded proteins, the small (S) or major, the middle (M), and the large (L) polypeptides. The L, M, and S proteins share a highly hydrophobic membrane region referred to as the S domain. Additionally, the L protein has a long region of 109 to 120 amino acids called pre-S1. The M protein has a 55 amino acid region identified as the pre-S2. Translation of these envelope proteins is initiated at three different in-frame start sites within a single ORF and is ended at a common termination codon (17).

▪ Figure 26.2 The hepatitis B virus (HBV) genome—the viral deoxyribonucleic acid (DNA) is partially double stranded. It encodes seven proteins from four open reading frames (ORFs)—envelope (surface), core, polymerase, and the X gene and three upstream regions: Precore, pre-S1, and pre-S2. A polymerase protein is covalently attached to the minus (–) strand and a capped oligoribonucleotide is attached to the plus (+) strand. Direct repeats 1 and 2 (DR1 and DR2) are 11 base pairs repeat sequences with template functions during replication.

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The core gene consists of the precore and core regions. The precore–core region encodes HBcAg and hepatitis B e-antigen (HBeAg) (18). The production of HBcAg is derived by an initiation AUG codon in the core gene, whereas HBeAg requires translational initiation from an AUG codon upstream of the core gene on the precore messenger RNA (mRNA). This 25kDa precore–core fusion protein is processed by two cleavage events to generate a final circulating 16-kDa HBeAg fragment. Mutations emerging in the precore and core promoter regions result in reduced levels of HBeAg expression (19). Similarly, a recent novel class of mutations immediately preceding the precore AUG codon has been shown to reduce HBeAg expression by a leaky scanning mechanism facilitating early HBeAg seroconversion in carriers of the virus (20). Expression of HBeAg has been shown to be nonessential for virus viability in animal models and humans (17), and its precise biologic role in the life cycle of the virus remains unclear. HBeAg may serve an immunoregulatory function in the infected host. The polymerase-coding region is specific for the viral polymerase involved in DNA synthesis, as will be discussed in the following sections. The viral X gene codes for a 16-kDa protein termed the HBx, which exhibits pleiotropic activities. Absence of functional HBx in vivo has been shown to reduce core gene expression, supporting the hypothesis that an essential function of HBx is to enhance obligatory virus gene expression during infection (21). HBx also plays an important role in modulating host cell signal transduction and activating several cellular signaling pathways. Distinct from the transactivation, HBx modulates the DNA repair processes and as such has been implicated in the pathogenesis of HCC (22).

Hepatitis B Virus Life Cycle The life cycle of HBV (Fig. 26.3) has been elucidated from studies in animal models and tissue cultures.

Entry and uncoating The cycle begins by viral attachment to the host cell membrane through the envelope protein. Although the precise identity of the actual cellular receptor(s) remains unknown, the pre-S1 domain in the L-envelope region appears to be directly involved in the viral attachment to the host cell surface (23). The heat shock protein (hsp) 70 may also be involved in this process (24). After membrane fusion, the envelope is stripped P.714 off and the nucleocapsid is released into the cytoplasm. Little is known about the postbinding steps in viral entry. It is likely, however, that the capsid “escorts” the viral DNA to the nucleus. Once in the nucleus, the partially double-stranded DNA is converted (or repaired) by viral polymerase into covalently closed circular DNA (cccDNA). This requires removal of its terminal structures (RNA and P protein), repair of the singlestranded gap region, and covalent ligation of the DNA termini.

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▪ Figure 26.3 Schematic representation of the life cycle of hepatitis B virus (HBV) (see text for explanation). L, M, and S are large-, middle-, and small-surface envelope proteins, respectively; ER, endoplasmic reticulum; RNA, ribonucleic acid; cccDNA, covalently closed circular deoxyribonucleic acid; mRNA, messenger ribonucleic acid; Pol II, polymerase II; Pg, pregenomic.

Transcription Nuclear cccDNA serves as the template for transcription by host RNA polymerase II. Persistence of the virus in infected cells during chronic infections is likely to be dependent on generating, maintaining, and regulating the pool size of transcriptionally active cccDNA molecule. Two classes of transcripts are synthesized from cccDNA, the genomic and the subgenomic classes. Both classes contain several transcripts, all unspliced and polyadenylated at a common position within the core gene. The subgenomic transcripts function as mRNA for the translation of the envelope proteins (L, M, and S proteins) and HBx protein (25). The two genomic mRNAs encode the precore, core, and polymerase ORFs. The HBV DNA contains promoters corresponding to independent transcription from pre-S1, pre-S2/S, core, X, and possibly, precore. The HBV pre-S1 promoter directs transcription of the 2.4-kb large envelope, while the S promoter directs the transcription of several mRNAs of about 2.1 kb, which are translated to produce pre-S2 (middle) and S (small)

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HBsAg proteins. The core promoter directs the transcription of pregenomic mRNA and precore mRNA. The precore mRNA translates the precore protein, while the pregenomic RNA serves as the template for reverse transcription. The pre-S1 and precore promoters are exclusively liver specific. Two regions of the HBV DNA are identified to have the properties of transcription enhancers (26,27). These enhancers stimulate transcription in cis configuration in a position- and orientation-independent way. Enhancer I (En I) is located between the S and X ORF, while En II is located just upstream of the core promoter. The activity of En II is largely restricted to hepatic cells and is therefore responsible for activating viral replication in a liver-specific manner (28). In contrast, En I functions in hepatic and nonhepatic cells, strongly upregulating all the major HBV promoters (29,30).

Genomic replication The first step in replication involves incorporation of viral RNA into the core, together with the polymerase. This encapsidation process is highly selective. The main trigger of this process is binding of the polymerase protein to a 5′-proximal stem loop structure called ε P.715 (which acts as an encapsidation signal) on the pregenomic RNA. Mutations in the polymerase ORF allows capsid formation but not RNA encapsidation. This reaction also requires host proteins such as chaperone hsp90 (31). Encapsidation then proceeds by packaging the viral pregenomic RNA bound to the viral polymerase protein into core particle (32) together with hsp90, forming the nucleocapsid (33).

Viral deoxyribonucleic acid synthesis Within the viral nucleocapsid, reverse transcription of the pregenomic RNA occurs. The pregenomic RNA is terminally redundant (200 nucleotides), containing the ε stem loop and a copy of the short DR1 sequence. There is growing evidence that initiation of the viral DNA minus strand synthesis occurs within ε and not DR1 as initially thought (34,35). This is initiated by the binding of polymerase to ε, generating a polymerase-linked oligonucleotide of about four nucleotides. These four nucleotides are homologous to the four nucleotides within DR1, allowing DNA transfer and annealing to this position. The strand transfer reaction occurs efficiently and is selectively directed to the 3′ copy of DR1. Once this occurs, elongation of the minus strands proceeds to the end of the template, completing minus strand synthesis. The minus DNA strand serves as the template for synthesis of the plus DNA strand. Plus-strand synthesis is initiated at DR2 and primed by capped oligonucleotides derived from the 5′ of pregenomic RNA. Once cleaved, the new RNA primer is translocated to the 5′ end of the minus strand to base pair with the DR2 region, forming the plus strand. The steps involved in the translocation process are poorly understood. Elongation of the plus strand then proceeds to the 5′ end of the minus strand DNA template, at which point the template becomes

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exhausted. At this stage, another transfer is required to complete the plusstrand synthesis. This transfer is made to the 3′ end of the minus strand DNA and is facilitated by eight nucleotides of the sequence derived from the terminal redundancy in the pregenomic RNA. Annealing of the nascent plus-strand DNA to the 3′ end of the minus strand circularizes the DNA and allows further elongation. Finally, the relaxed circular double-stranded DNA virion (the mature DNA) is formed, with the 5′ end covalently bound to a primer protein. The resulting nucleocapsid either moves back to the nucleus and recycles its genome, thereby replenishing the cccDNA pool (36), or buds into the postendoplasmic reticulum where virus envelopment occurs.

Viral assembly and release S proteins are synthesized in the rough endoplasmic reticulum and then transported to the postendoplasmic reticulum and pre-Golgi regions, where budding of the nucleocapsid occurs. A linear sequence in pre-S domain (residues 103 to 124) of the L envelope protein has been implicated in HBV envelopment and secretion. Other regions in the S domain are also important in viral secretion. Finally, the assembled HBV virion is transferred to the Golgi to be secreted.

Natural History of Hepatitis B Virus Infection Primary HBV infection is clinically symptomatic in 30% to 50% of persons older than 5 years, yet most patients (95%) will clear the virus, resulting in lifelong immunity. In contrast, 30% to 50% of persons who acquire the infection before the age of 5 years develop chronic hepatitis B infection. The natural course of the HBV infection has three phases: The first is the immune tolerance phase seen in children and adolescents who acquire HBV perinatally. In this phase, patients are HBeAg positive and have high serum levels of HBV DNA but normal serum aminotransaminase (alanine aminotransferase [ALT]) levels and minimal histologic activity. The second is the immune clearance phase, occurring in adolescents and adults, during which HBV replication declines, accompanied by both increased serum ALT levels and inflammatory activity in the liver. Seroconversion of HBeAg to anti-HBe may then ensue. During this phase, or even after the seroconversion to anti-HBe, replication-competent HBV variants with mutations in the precore or core promoter regions may emerge, preventing HBeAg production. Of interest, HBeAg-negative disease is now becoming the predominant form of chronic HBV infection (37). In the third lowreplicative phase, serum HBsAg persists, but HBeAg is no longer detectable and HBV DNA can only be detected by sensitive polymerase chain reaction (PCR) assays. In this inactive HBsAg carrier state, patients are usually asymptomatic and liver disease is inactive. This stage may last indefinitely; however, a proportion of patients may undergo reactivation with the reappearance of high levels of HBV DNA and/or HBeAg. A recent 30-year follow-up study reported the natural course of HBsAg carriers to be generally favorable (38). In particular, these patients did not seem to develop clinically significant liver disease, hepatocellular cancer, or other liver-related morbidity or mortality at a higher rate than uninfected

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controls. In chronically infected patients, cirrhosis and HCC are the two major complications associated with increased morbidity and mortality. In HBeAgpositive patients, the 5-year cumulative risk of developing cirrhosis ranges from 8% to 20% (39). This incidence is even higher in HBeAg-negative patients. Predictors for the development of cirrhosis include older age, P.716 evidence of persistent viral replication, HBV genotype C, excess alcohol intake, and coinfection with HCV, delta hepatitis, or human immunodeficiency virus (HIV) (40,41). Once cirrhosis is established, the 5year mortality rate is 16% for patients with compensated cirrhosis but increases to 60% to 80% among those with decompensated cirrhosis. Overall, it is estimated that over 250,000 patients worldwide die annually from HBV-related liver disease (13). HBV-infected patients have a 100-fold increased risk of developing HCC compared to uninfected patients (42). The risk of HCC correlates with age, gender, HBV-replicative status (HBeAg status), and the severity of the underlying liver disease, particularly the presence of cirrhosis (42,43).

Immunopathogenesis of Hepatitis B Virus Infection The nature of the immune response is crucial for protection from the disease, viral resolution, and the extent of liver injury in response to HBV infection. During acute infection, innate, humoral, and adaptive immune responses are activated and must act in concert to clear the virus. The earliest events after infection involve noncytolytic control of viral replication through interferon-γ (IFN-γ) and tumor necrosis factor-α (TNFα). These cytokines are initially produced by infected hepatocytes and then by cells of the innate immune system including natural killer (NK) cells and NK-T cells (44). Formation of neutralizing antibodies to HBV envelope antigens is an important T cell–dependent process that aids viral clearance by interfering with viral entry into host cells. However, for complete viral eradication, a strong, polyclonal, and multispecific CD4 and cytotoxic lymphocyte (CTL) immune response is essential. Self-limited infection is therefore characterized by a vigorous CD4 response directed against multiple epitopes within the HBV antigen, in particular, the nucleocapsid (45). This response also supports the induction and activation of CTLs that mediate apoptosis of infected hepatocytes through Fas/Fas-ligand binding and the release of lytic granules (46). Virus-specific CTLs also trigger the production of other cytokines including TNF-α, IFN-γ, interleukin 2, and NK cells, which control viral replication through noncytolytic mechanisms (47). In those patients who become chronically infected, the immune response, although ineffective, appears to persist and therefore mediates ongoing tissue injury. In this context, CTLs induce both direct damage to hepatocytes and produce cytokines that lead to the recruitment of antigennonspecific inflammatory cells (e.g., macrophages, NK cells) and IFN-γ. This nonspecific inflammatory response accounts for most of the

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subsequent tissue damage in chronically infected patients (48).

Treatment of Hepatitis B Virus Infection In the last few years, new therapies have emerged for managing chronic HBV infection. However, a number of unresolved issues remain, including whom to treat, how long should the treatment continue, and what are the optimal treatment regimens to be used in various subsets of patients. Initial therapeutic regimens in HBeAg-positive patients with chronic hepatitis B consisted of 4- to 6-month courses of IFN-α, at varying dosages between 5 million units (MU) daily and 10 MU thrice weekly, achieving HBeAg loss in 33% of patients, compared with 12% of controls (49). In contrast, in HBeAg-negative HBV patients, a 6-month course of IFN therapy was associated with very low sustained response rates because of frequent relapses after the cessation of therapy. Subsequently, prolonged courses of IFN were reported to improve sustained response rates up to 20% to 25% in these patients (50). The wide spectrum of IFN-related side effects, cost, and the inconvenience of administration are the main drawbacks of this therapy. Pegylated IFN has better pharmacokinetics than standard IFN, allowing once-weekly dosing. A recent worldwide trial evaluating its efficacy in largely Asian HBeAg-positive patients reported an HBeAg seroconversion rate of 32% after 48 weeks of pegylated IFN monotherapy (51). This seroconversion rate was higher than that achieved in patients receiving either a combination of pegylated IFN and lamivudine (27%) or lamivudine alone (19%) (51). Lamivudine, a nucleoside analog, resulted in HBeAg seroconversion rates of 17% in patients after 12 months of treatment, at 100 mg daily, compared to 6% in untreated patients (52). It is administered orally and has few side effects. Moreover, longer treatment durations in HBeAg-positive patients enhances response rates, with seroconversion occurring in 27%, 40%, 47%, and 50% of patients receiving treatment for 2, 3, 4, and 5 years, respectively. In HBeAg-negative patients, however, a 12-month course of lamivudine is less effective, maintaining remission (as assessed by undetectable HBV DNA levels) in less than 15% of patients after stopping therapy (53). Importantly, lamivudine has also been reported to suppress HBV replication in 60% to 100% of patients awaiting liver transplantation (54,55). In these patients, lamivudine has been shown to stabilize the progression of liver disease, delay the need for liver transplantation, and improve survival among patients awaiting liver transplantation (55,56,57). A significant problem with lamivudine is that to achieve the desired therapeutic benefit, longer treatment durations are often required. However, with longer courses of therapy, viral-resistance mutations, particularly the YMDD variant, emerge, with the risk P.717 reaching 50% after 3 years of therapy. The emergence of resistance has been associated with significant and serious flares in disease activity. Unfortunately, very high rates of relapse occur on discontinuing lamivudine

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therapy, making it more likely to become a longer-term therapy. Adefovir dipivoxil is a nucleotide analog of adenosine. In HBeAg-positive patients, a 12-month course of adefovir, at a daily dose of 10 mg, achieved loss of HBeAg in 24% of patients compared to 11% in the placebo group (58). In addition, adefovir has also been shown to be effective in suppressing HBV DNA in patients who develop lamivudine resistance. In HBeAg-negative patients, initial reports indicated that a 12-month course of adefovir resulted in a significant virologic response in 50% of patients compared to placebo (59). However, a recent follow-up data suggests that this benefit was not sustained once treatment was stopped (60). Side effects are uncommon with adefovir; however, the drug is expensive and renal dysfunction may occur. Resistance to adefovir is being increasingly reported, although it is less common than that with lamivudine and tends to emerge later in the course of treatment (61). Entecavir is a cyclopentyl guanosine analog. Results of phase III studies confirmed the efficacy and safety of entecavir when given for 48 weeks as compared with lamivudine in suppressing HBV DNA in HBeAg-positive and HBeAg-negative patients and in those with lamivudine resistance (62). A dose–response relationship has been observed. Entecavir is well tolerated at all doses, and resistance to the drug is rare. Emtricitabine and telbivudine are under evaluation for the treatment of chronic hepatitis B infection. Their clinical utility and approval are awaited.

Hepatitis C Virus Epidemiology An estimated 3% of the world's population is infected with HCV (63,64). Globally, HCV infection accounts for 70% of chronic hepatitis cases. The prevalence rate of HCV infection ranges from 20% in highly endemic areas such as Egypt to 1.8% in the United States and 1.5% in Australia. Parenteral exposure accounts for most HCV infections. With the advent of routine blood screening measures, the importance of HCV transmission from infected blood products has declined. Therefore, injection drug use is the primary source of HCV acquisition, and up to 90% of intravenous drug users are HCV infected (65). Other risk factors include occupational exposure, hemodialysis, medical reuse of infected needles, and tattoos; vertical (mother-to-infant) and sexual transmission are uncommon.

Hepatitis C Virus Genome and Proteins HCV is a member of the Flaviviridae family, of which yellow fever virus and pestiviruses are other members (66). All members of this family are smallenveloped viruses containing a positive-sense, single-stranded RNA genome. The size of the HCV particle is between 30 and 80 nm. The HCV genome is 9.6 kb in length, containing a single ORF flanked by 5′ and 3′ untranslated regions (UTRs) (66) (Fig. 26.4). The 5′ UTR region of the HCV genome contains an IRES for the initiation of translation. This region of

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highly conserved nucleotide sequences has been used as the major target for commercial RT-PCR assays. The 3′ UTR region of the genome terminates in polyuridine (poly U) ribonucleotides, followed by another highly conserved region of 98 to 100 nucleotides designated the X tail, which may have functional importance in viral replication (67). The HCV ORF encodes a polyprotein that may vary in length between 3,010 and 3,033 amino acids in a strain-specific manner. Translation of the HCV polyprotein in the endoplasmic reticulum of the infected cell gives rise to at least 10 mature proteins (Figure 26.4). The structural proteins include nucleocapsid protein and two envelope glycoproteins, E1 and E2. This is followed by a small integral protein, p7. The nonstructural (NS) proteins include NS2, NS3, NS4a, NS4b, NS5a, and NS5b. The HCV core is a basic protein with RNA-binding properties. It is believed to form the nucleocapsid in association with the viral RNA. Additionally, the core protein has been shown to modulate the transcription and translation of several cellular genes (68) and have oncogenic effects in cell cultures and transgenic mice. E1 and E2 envelope proteins coat the virus. Comparison of HCV sequences has shown two hypervariable regions (HVRs) within E2, HVR1 and HVR2. Mutations in HVR1 emerge rapidly under selective host immune pressure (69). E2 may elicit the production of virusneutralizing antibodies, resulting in immune selection of HCV genomes with escape mutations in HVR1 (69). In addition, E2 has been shown to be involved in the binding process of HCV to the host cell. The function of p7 is partly unknown; however, it may be necessary for HCV replication and may act as a viroporin (70,71). NS2 has protease activity. Together with the N terminus of NS3, NS2 forms an NS2/NS3 protease responsible for autocatalytic cleavage at the NS2/NS3 junction (72). NS3 has both protease and helicase activities. NS4a essentially functions as a cofactor for NS3. Moreover, HCV NS3/4a serine protease has been shown to block the action of IFN regulatory factor-3, P.718 a key cellular antiviral molecule (73). The function of NS4b is unknown, while NS5a plays a role in modulating the effect of IFN on the virus. A region in NS5a has been identified as an IFN-sensitive determining region (ISDR) where a close association is demonstrated between mutations in this region and sensitivity to IFN therapy (74). In addition, NS5a has been shown to be a potent inhibitor of the IFN-induced protein kinase PKR, an antiviral molecule (74). NS5b possesses RNA-dependent RNA polymerase activity and is essential for RNA synthesis and viral replication. The details of how viral RNA-dependent RNA polymerase initiates RNA synthesis remain poorly understood.

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▪ Figure 26.4 Schematic representation of the HCV genome. Unshaded regions indicate the major structural proteins: Core (c), envelope (E1 and E2), and p7. The shaded region indicates the nonstructural proteins NS2, NS3, NS4a/NS4b, and NS5a/NS5b. At the 5′ untranslated region (5′-UTR) resides the internal ribosomal entry site (IRES).

Hepatitis C Virus Life Cycle The mechanism by which HCV enters target cells is still unknown, but it involves the HCV glycoproteins E1 and E2. Host molecules observed to play a role in HCV cell entry include dendritic cell-specific intercellular adhesion molecule 3-grabbing nonintegrin (DC-SIGN), and liver/lymph node-specific intercellular adhesion molecule 3-grabbing integrin (L-SIGN) (75,76). In particular, CD81 has been shown to function as a postattachment entry coreceptor, while other unknown cellular factors act in concert with CD81 to mediate HCV binding and entry into hepatocytes (77). Similarly, lowdensity lipoprotein receptor (LDLR) has been shown in vitro to act as entry point for HCV (78,79). The virus selectively fuses with liver cell plasma membranes. Once fusion of the viral lipid coat and host plasma membrane is complete, the viral core enters the host cell (Fig. 26.5). The HCV genome can be directly read by the host's ribosomes. During translation the ribosomes produce a polyprotein that is then processed into the 10 HCV proteins. The enzymes NS3 serine protease and NS2/NS3 protease cleave the polyprotein. When adequate RNA transcriptase is produced, an antisense version of HCV RNA is made to serve as a template for RNA replication. The enzyme NS3 helicase unwinds the RNA during replication, and NS5b, or the HCV RNA– dependent RNA polymerase, catalyzes RNA synthesis. The newly produced RNA and processed proteins assemble to form viruses that travel to the inside portion of the plasma membrane and then exit the host cell. Recently, a full-length genotype 2a HCV genome that replicates and produces infectious virus particles in cell culture has been described (80).

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This system promises to lay the foundation for future in vitro studies to examine and shed further light on the life cycle of the virus.

Natural History of Hepatitis C Virus Infection Acute HCV infection is usually asymptomatic, and therefore, the timing of disease onset is usually assumed on the basis of exposure to specific risk factors. Early studies suggested that most acutely infected patients (80% to 90%) developed chronic HCV infection. However, certain more recent studies with longer follow-up indicate that only approximately 50% of acutely infected patients progress to chronicity (81,82,83). Progression of chronic HCV infection is usually slow, with advanced disease developing only 10 to 30 years or even longer after infection (84,85). The degree of fibrosis on the initial liver biopsy is the main determinant of progression to cirrhosis and the development of subsequent liver complications (85,86). Other factors associated with increased progression to fibrosis include male gender, older age at initial infection, excess alcohol, coinfection with HBV or HIV, and the presence of hepatic steatosis. In patients with cirrhosis, the 5-year risk of decompensation is 18%, with a 5-year survival probability around 50% in those who decompensate (87,88). Moreover, in patients with cirrhosis, the 5-year risk of developing HCC is around 7% and 18% in those P.719 with compensated and decompensated liver disease, respectively (88).

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▪ Figure 26.5 Schematic representation of the life cycle of hepatitis C virus (HCV). The main steps in the cycle are viral entry and uncoating, translation, replication, and packaging (see text for details). HCV RNA, hepatitis C virus ribonucleic acid.

Immunopathogenesis of Hepatitis C Virus Infection It is unclear why a substantial proportion of patients with HCV fail to permanently eradicate the virus after acute infection. Several arms of the immune system are important in orchestrating viral clearance. Animal studies indicate that sustained or even transient clearance of HCV is clearly associated with an intrahepatic immune response characterized by increased expression of IFN-γ–inducible genes (89). The upregulation of these genes has been observed to occur as early as 2 days after infection, reflecting activation of the innate immune response and its crucial role in viral clearance (89). Similarly, after acute infection, high and persistent titers of neutralizing antibodies have been detected in patients in whom the virus is eradicated, in contrast to a low and nonsustained neutralizing antibody response in those with persistent infection (90). These neutralizing antibodies are however variant specific and, therefore, do not

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provide protection against reinfection with other viral variants (91,92). The cellular immune response also plays a major role in eradicating HCV infection. Multispecific vigorous intrahepatic CD4 and CTL responses are detected in subjects who have successfully cleared an acute HCV infection (93,94). The CD4 response associated with viral clearance is dominated by a T H 1 cytokine profile with increased IFN-γ production. This T H 1 cytokine response has been shown to coincide with a decline in the levels of viremia in acutely infected chimpanzees (89,95). The CD4 response is also essential for the functional maturation of CTL cells. Successful viral elimination has been shown to be associated with the induction of an early intrahepatic CTL population that possesses cytolytic and noncytolytic activities (95). The CTL cytolytic response is associated with acute hepatitis, and the vigor of the response parallels serum ALT levels and the extent of liver injury (96,97). However, HCV clearance and resolution of infection coincides with the appearance of CTL-induced cytokines (mainly IFN-γ) (96,97). In addition to the immune response, nonimmunologic genes, in particular, genes associated with lipid metabolism, have been recently recognized to influence HCV clearance (89). Genes related to the serum response element–binding protein signaling pathway appeared to enhance viral replication (89). Liver injury in patients with chronic infection is primarily immune mediated; however, a cytopathic effect is apparent in association with HCV genotype 3 infection and in immunosuppressed patients. In chronic liver injury, the HCV-specific CTL immune P.720 response may target not only virally infected cells but also uninfected bystander hepatocytes through the release of soluble proapoptotic mediators such as Fas-ligand and soluble TNF-α (98,99). In addition, antigen-nonspecific recruitment of T cells occurs at the site of hepatic damage in chronic hepatitis, further contributing to the extent of liver injury (100). Nonimmunologic factors such as steatosis and insulin resistance have also been linked to the progression of liver injury in HCV-infected patients. In particular, in patients infected with HCV genotype 3, steatosis and insulin resistance are primarily viral mediated (cytopathic), whereas host factors, principally those associated with insulin resistance and its clinical attributes, are responsible for the development of steatosis in genotype 1– infected patients. The molecular mechanisms responsible for these observations have not been elucidated (101,102).

Treatment of Hepatitis C Virus Infection In the minority of patients presenting with acute HCV, increasing data indicate that IFN treatment is effective in preventing the progression to chronicity. In particular, a 6-month course of pegylated IFN-α in acute HCV infection has been shown to achieve sustained viral clearance rates (SVRs) of 95% 6 months after treatment (103). These patients remain virus free in the long term (104). There are still, however, several unresolved issues

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concerning acute HCV treatment including the timing and optimal duration of therapy and identifying those most likely to benefit from therapy, in particular, intravenous drug users. Incremental advances have also been made in relation to therapy for chronic HCV infection. Presently, the combination of pegylated IFN-α and ribavirin is the standard therapy for chronic HCV infection. Response and duration of treatment (24 to 48 weeks) is dependent on the infecting genotype, with 76% to 80% of patients with genotypes 2 and 3, but only approximately 40% to 45% with genotypes 1 and 4, achieving an SVR 6 months after completing therapy (105,106). However, SVR after pegylated IFN-α and ribavirin therapy are approximately 10% lower for patients with bridging fibrosis or cirrhosis (105,106), and hence the benefits of maintenance pegylated IFN-α in this group of patients is under evaluation. The benefits of combination therapy also extends to other “difficult-to-treat groups” such as those with recurrent HCV infection after liver transplantation or those with HCV/HIV coinfection (107). In all these groups, however, drug-related adverse events are common, requiring dose reduction and the frequent use of supportive growth factors.

Hepatitis Delta Virus Epidemiology HDV has a worldwide distribution but its infectivity relies on HBV envelope proteins (108). Therefore, it has been estimated that around 5% of global HBsAg carriers are also infected with HDV. However, the geographic distribution of HDV and HBV differ, with high HDV prevalence rates in Mediterranean countries, where interfamilial transmission predominates (109). In contrast, HDV infection is uncommon in the United States and northern Europe, where transmission is usually through intravenous drug use (110). Other modes of HDV transmission are similar to HBV spread and include hemodialysis, and sexual and, uncommonly, vertical transmission (110). Given the close link between HDV and HBV, strategies employed to control HBV in recent years, in particular vaccination, have resulted in a significant decrease in the incidence of HDV infection.

Hepatitis Delta Virus Genome and Proteins The HDV virion is a spherical particle with a diameter of 36 to 43 nm. Its envelope protein is supplied by the HBsAg and contains the HDV genome. The HDV genome is a 1.7-kb single-stranded circular RNA, which encodes a single structural protein, the HDAg, the only gene product of the virus (111). There are two isoforms of the HDsAg, a small form (S-HDAg, 195 amino acids) required for HBV DNA replication and a large form (L-HDAg, 214 amino acids) required for virion assembly and inhibition of replication (112,113). The genome sequence of HDV is nearly self-complementary such that about 70% of the nucleotides are base paired on a rod-like double-stranded RNA structure (genomic and antigenomic strands) (111). Moreover, its genomic and antigenomic RNA have the capacity to act as ribozymes directing self-

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cleavage and self-ligation during HDV replication.

Hepatitis Delta Virus Life Cycle HDV enters the cells through a cellular receptor shared by HBV; however, the identity of this receptor is still unknown. HDV is then transferred to the nucleus, where replication occurs. The HDV genome utilizes host RNA polymerase II to direct RNA-dependent RNA synthesis. Three forms of RNA gather in the infected hepatocyte during HDV replication—genomic RNA, its complement antigenomic RNA, and an antigenomic-sense mRNA. The antigenomic mRNA encodes the S-HDAg, which promotes the transcription/replication process (114,115). HDV replication occurs in the P.721 nucleus by a double–rolling circle mechanism (116); the ribozymes are central to this mechanism. According to this mechanism, the circular genomic RNA serves as a template for an antigenomic RNA intermediate. This RNA intermediate is processed by autocatalytic cleavage at the ribozyme sites to yield monomeric linear RNA. In the final step, the linear RNA is ligated by HDV ribozyme and a host RNA ligase enzyme into an antigenomic, circular RNA. The circular antigenomic RNA subsequently serves as a template for a second round of rolling-circle replication. During replication, a unique event called editing occurs, allowing the generation of L-HDAg from S-HDAg. Up to 30% of the S-HDAg is edited by a host RNA– modifying RNA enzyme called adenosine deaminase. This changes the UAG stop codon of S-HDAg to a tryptophan (UGG) codon, resulting in the extension of the C terminal of the S-HDAg by 19 amino acids to generate the L-HDAg (117). Subsequently, L-HDAg inhibits viral replication and triggers the assembly and copackaging of viral particles (118). The editing process is therefore essential for achieving the balance between the conflicting but essential functions of the S-HDAg (RNA replication) and the L-HDAg (RNA inhibition). Virion assembly is triggered by an interaction between L-HDAg and HBsAg. The mechanisms by which this interaction occurs have not yet been fully elucidated.

Natural History of Hepatitis Delta Virus Infection HDV infection can occur in three settings: An individual who becomes coinfected simultaneously with HDV and HBV, a chronic HBV-infected patient who develops superinfection with HDV, and finally, reinfection following liver transplantation. The clinical expression and outcome of each of these modes of infection are somewhat different. In patients who develop coinfection, acute delta infection (and similarly that of HBV) is often self-limiting and progression to chronic liver disease is uncommon, occurring in around 2% of cases. The clinical spectrum of coinfection may range from asymptomatic disease to fulminant hepatitis. HDV superinfection primarily affects intravenous drug users and chronic HBV carriers in developing countries. The preexisting HBV provides the substrate for rapid replication and spread of HDV, hence superinfection

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usually results in chronic HDV infection or, alternatively, may cause severe fulminant hepatitis. Patients chronically infected with both viruses have progressive liver disease, with most developing cirrhosis. Moreover, the risk of HCC is increased threefold in patients with cirrhosis and dual HBV/HDV infection (41). After liver transplantation, HDV reinfects the graft soon after surgery, resulting in subclinical infection that becomes symptomatic only if HBV reactivates, producing a florid hepatitis that does not usually respond to therapy (119).

Immunopathogenesis of Hepatitis Delta Virus Infection It is not clear whether the enhanced disease severity observed from dual HBV/HDV infection is due to the immune response against viruses, a direct HDV cytopathic effect on hepatocytes, or a combination of these processes. The observation that the extent of portal inflammation correlates with the number of HDAg-positive cells suggests an immunologic mechanism contributing to the liver lesion. Investigations into a potential cytopathic role for the delta virus, however, have generally yielded conflicting results. A cytopathic effect has been suggested because HDAg produces significant cell death in transfected cell lines (120). Additionally, microvesicular steatosis has been frequently observed in association with epidemics of HDV infection and in patients undergoing transplantation who exhibit the delta virus (121). In contrast to these observations, transgenic mice expressing HDAg develop no hepatic damage (122). Similarly, in patients undergoing transplantation who are reinfected with HDV alone, hepatitis does not ensue until the reappearance of HBV antigens in the graft (121,123).

Treatment of Hepatitis Delta Virus Infection Treatment of chronic hepatitis due to infection with HDV/HBV is unsatisfactory, and IFN-α is the only agent found to have any effect. To achieve therapeutic benefit, patients require treatment with a high dose of IFN-α (5 to 9 MU three times weekly) for at least 12 months (124). This regimen has been shown to result in sustained normalization of ALT levels and improved liver histology in 50% of treated patients. A recent 14-year long-term follow-up report of patients who received this treatment showed that responders also achieved clinical and survival benefits (125). Some long-term responders cleared HDV RNA and, eventually, HBV (125). Similar long-term improvements are observed in hepatic necroinflammatory activity and fibrosis (125). Unfortunately, IFN-related side effects are common in this group, particularly psychiatric problems, often leading to discontinuation of therapy (126,127). Results with other antiviral agents have been disappointing. Lamivudine alone or in combination with IFN was not associated with any histologic or biochemical improvement (128,129). Hence, in contrast to treatment of HBV infection, available evidence does not support the use of nucleoside

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analogs for the treatment of chronic HDV infection. P.722

Hepatitis E Virus Epidemiology Hepatitis E is a worldwide public health problem and particularly causes acute hepatitis in adults through most of Asia, the Middle East, and northern Africa (130,131). In India, acute HEV is responsible for 60% of patients presenting with fulminant hepatitis. Moreover, cyclic outbreaks of HEV have occurred in India, Iraq, Sudan, Mexico, and parts of Asia. Sporadic cases of acute HEV have occurred in both South America and Europe. In contrast, cases of HEV are rare in the United States and are primarily linked to travel to endemic regions (130). HEV is enterically transmitted, and epidemics are usually linked to contaminated water supplies. Parenteral transmission may occur in endemic areas (132) and vertical (mother-to-infant) transmission has also been reported (133). In contrast to HAV, which predominantly affects children and spreads secondarily in 15% of patients, HEV mainly affects young adults and has only a low rate of secondary spread (2%).

Hepatitis E Virus Genome, Proteins, and Life Cycle HEV is a small spherical nonenveloped RNA virus of approximately 30 nm diameter. Although its genomic structure shares some morphologic similarities to the Caliciviridae and Picornaviridae families, HEV remains unclassified at this time. The viral genome consists of a 7.5-kb plus-strand RNA with a 5′ capped end and a polyadenylated 3′ end (134). The genome (Fig. 26.6) contains three distinct ORFs (ORF1, ORF2, and ORF3) (134). ORF1 extends approximately 5 kb from the 5′ end and encodes polyproteincontaining sequence motifs of methyltransferase, papain-like protease, RNA helicase, and an RNA-dependent RNA polymerase. ORF2 begins 37 bp downstream of ORF1 and extends approximately 2 kb to the termination codon. The sequence of ORF2 suggests that it encodes the gene for the capsid protein. Moreover, ORF2 contains important epitopes that can induce neutralizing antibodies and has therefore been the focus of vaccine development (135). Finally, ORF3 partially overlaps ORF1 and ORF2 and encompasses only 369 bp. It encodes a protein that may play a role in viral infectivity (136). The genomic organization of the virus is consistent with the 5′-end encoding nonstructural and the 3′-end encoding structural viral gene(s) (134).

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▪ Figure 26.6 The hepatitis E genome—the genome is a capped, single-stranded positive-sense ribonucleic acid (RNA) molecule. It contains three distinct open reading frames (ORFs). ORF1 encodes replicative proteins including methyltransferase (MT), papain-like protease, helicase, and RNA-dependent RNA polymerase (RDRP). ORF2 encodes the capsid protein. The small overlapping ORF3 encodes a protein of unknown function.

The virus cannot be grown reliably and reproducibly in cell cultures and, therefore, the replication cycle is poorly understood. It is assumed that the virus attaches to receptor sites on hepatocytes and, possibly, biliary and intestinal cells. After uncoating, the genome is translated to produce ORF, subsequently cleaved by cellular proteases. It is postulated that replicative negative strand RNA intermediates are synthesized and then act a template for the synthesis of genomic and subgenomic positive strands (137). The mechanisms involved in viral assembly and transport are not known.

Natural History and Immunopathogenesis HEV causes an acute, self-limiting illness with no chronic sequelae. Serologic follow-up studies of infected patients confirmed that antibodies to HEV provide long-term protection against the disease (138). Acute HEV infection, however, results in a high mortality among pregnant women, particularly during the third trimester, with case fatality rates ranging from 5% to 25% (133). The mechanisms involved in hepatocyte destruction during acute HEV remain unknown. In HEV-infected cynomolgus macaques, the lymphocytes involved in the liver lesion have been found to be positive for a cytotoxic/suppressor immunophenotype (139). Additionally, hepatocyte culture of the cynomolgus monkey inoculated with a transmissible stool extract of HEV did not show any cytopathic change (139). Therefore, P.723 the data from this single study suggest an immune-mediated rather than a

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direct cytopathic mechanism for the liver injury in HEV infection.

Treatment of Hepatitis E Virus Infection There is no specific treatment for acute HEV infection. Public health strategies to improve sanitation and handling of food and water are currently the best prophylaxis against the disease (131). Vaccine development strategies are under way, particularly examining the ORF2encoded HEV proteins.

Hepatitis G Virus Epidemiology The HGV and the GB-C virus are two variants of the same virus and are therefore often referred to in the literature as GBV-C/HGV; in this review we use the term HGV (140). A direct association with liver pathology, however, is still lacking, and it is therefore unclear whether HGV is a hepatotropic virus. HGV is distributed worldwide, and carriage of the virus has been documented among healthy individuals and different patient groups (141). Between 1% and 4% of healthy blood donors have detectable serum HGV RNA (141,142). The highest prevalence rates are in Thailand, Vietnam, and Africa while China, Japan, and the United States have low prevalence rates (143,144). The virus is frequently found in populations at risk for blood-borne or sexually transmitted viruses, and there is also evidence of transmission vertically from mother to infant (145,146). Because of shared modes of transmission, many patients with HGV are coinfected with other blood-borne viruses such as HCV, HBV, and HIV (147).

The Hepatitis G Virus Genome, Proteins, and Life Cycle GBV-C/HGV is a single-stranded positive-sense RNA virus, which is a member of the Flaviviridae. It has close sequence homology and genomic organization with HCV (148). The HGV genome is preceded by a 5′ UTR, which is followed by a long ORF (2,842 to 2,933 amino acids), terminating in a 3′ UTR. The structural proteins are E1 and E2, while the nonstructural proteins are NS2, NS3, NS4a, NS4b, NS5a, and NS5b. However, unlike HCV, the coding region for the core gene remains unknown. Also, the E genes are highly conserved among the various isolates of HGV, and therefore, there is no hypervariable region in the HGV genome (148). The 5′ UTR contains an IRES that is capable of directing cap-independent translation of the polyprotein (149). NS2 has a zinc-dependent protease, and the NS3 gene has a helicase motif and is likely to be essential for replication. NS5b gene encodes an RNA-dependent RNA polymerase (148), while the function of the other NS4 proteins is unknown. The exact site of HGV replication is unknown, although it appears that the virus replicates within lymphocytes and, perhaps, hepatocytes (150,151).

Natural History and Immunopathogenesis of

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Hepatitis G Virus The question of whether HGV contributes to liver disease either alone or in association with other chronic hepatitis virus infections has been extensively investigated with conflicting results, ranging from implicating the virus in cases of fulminant hepatitis to negating any role for the virus in liver disease. The prevalence rates of HGV associated with fulminant hepatitis has been reported to range from 5% to 15% (152,153). However, other studies sequentially examining the blood of patients with fulminant hepatitis concluded that the presence of HGV in them was accidental and coincided with the receipt of contaminated blood products in the course of therapy (154,155,156). Most individuals with HGV infection alone appear to have an asymptomatic course; many eventually clear the virus, developing antibodies to the E2 envelope glycoprotein that also protect against reinfection (144,146). The incidence of HGV among patients with HCV infection varies from 11% to 24% (157). However, HGV appears not to influence the clinical or virologic course of HCV infection nor does it have an impact on the response to IFN therapy (158,159). Whether HGV contributes to the development of HCC is still controversial, although it appears unlikely (160,161). More recently, coinfection with HGV and HIV has been shown to improve mortality and morbidity for the HIV-infected individuals and slow the progression to acquired immunodeficiency syndrome (AIDS) (162,163).

Herpesviruses Several other viruses, which are not primarily hepatotropic, may also cause hepatitis. These are usually herpesviruses, a family of double-strand DNA viruses, which can cause either chronic infections or enter a period of viral latency. So far, eight human herpesviruses have been identified: Herpes simplex virus 1 and 2 (HSV1 and HSV2), varicella-zoster virus (VZV), Epstein-Barr virus (EBV), Cytomegalovirus (CMV), and human herpesviruses 6, 7, and 8. P.724 HSV1 and HSV2 commonly produce self-limiting vesicular or ulcerative lesions primarily involving the orofacial (HSV1) or the genital areas (HSV2). In the immunocompromised host or neonates, generalized infections including hepatic involvement may occur. Neonatal disseminated HSV infection can cause rapidly progressive multiple organ failure, with an 85% mortality rate if left untreated (164). In adults, the risk factors for the development of HSV hepatitis include third trimester pregnancy, an underlying immune-modifying disease such as malignancy, or the use of immunosuppressive medications particularly in solid organ transplant recipients (165,166). The clinical presentation of HSV hepatitis is nonspecific and includes fever, abdominal pain, and flu-like symptoms. Up to 30% of patients may not have detectable mucocutaneous lesions (167). Most of those who progress to fulminant hepatitis display a characteristic pattern of liver test abnormalities, the so-called anicteric hepatitis, with minimal elevation of serum bilirubin levels in the presence of marked elevations in the levels of serum transaminases. Progressive liver failure

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often ensues. Disseminated HSV infection is treated with high-dose intravenous acyclovir (5 to 10 mg/kg three times daily) (168). VZV is primarily a self-limiting illness of childhood; however, reactivation of VZV occurs in the setting of advancing age or reduced immunity (169). Clinical hepatitis occurs in the context of disseminated VZV and can rarely be fatal. VZV is best managed with high-dose intravenous acyclovir (168). Latent CMV infections are often reactivated in the setting of immunocompromised hosts. AIDS patients, with low CD4 count are particularly at risk for symptomatic CMV infection. CMV is also a major pathogen in patients undergoing transplantation. CMV infection has been documented in 23% to 85% of liver transplant recipients; half will have symptomatic disease. Moreover, in recurrent HCV infection after liver transplantation, CMV reactivation increases the risk of hepatic fibrosis and allograft dysfunction (170). In immunocompromised hosts, typical liver lesions include CMV inclusion bodies in hepatocytes, vascular endothelium, and particularly, biliary epithelium. Ganciclovir is often used to treat CMV hepatitis; however, drug resistance may emerge and in these cases, foscarnet is the alternative agent of choice (171). Infectious mononucleosis, as a result of EBV infection, is usually associated with only mild hepatitis. Most cases resolve spontaneously, although acute hepatic failure in immunocompetent patients has occasionally occurred. In addition, primary or secondary EBV infection has been linked to an increased risk of lymphoproliferative disorders after solid organ transplantation (172). Human herpesvirus (HHV)-6 and HHV-7 are novel members of the betaherpesvirus family. The clinical effect of HHV-6 and HHV-7 reactivation in recipients of liver transplants who are also coinfected with CMV is now being recognized (173). In this regard, primary or secondary HHV-6 or HHV-7 infection after liver transplantation has been observed to be associated with predisposition to invasive and symptomatic CMV infection (173,174).

Annotated References Choo QL, Richman KH, Han JH, et al. Genetic organization and diversity of the hepatitis C virus. Proc Natl Acad Sci U S A 1991;88(6):2451– 2455. The authors describes the genetic diversity of HCV, most apparent within the putative 5’ structural gene region of the different HCV isolates. Cohen JI. Hepatitis A virus: insights from molecular biology. Hepatology 1989;9(6):889–895. The author provides a brief summary of each of the hepatitis virus and the changing patterns of viral epidemiology.

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Ganem D, Varmus HE. The molecular biology of the hepatitis B viruses. Annu Rev Biochem 1987;56:651–693. A thorough review of the molecular biology of the hepatitis B virus. Lai MM. The molecular biology of hepatitis delta virus. Annu Rev Biochem 1995;64:259–286. A comprehensive review explaining the genomic structure and life cycle of the hepatitis delta virus. Linnen J, Wages J Jr, Zhang-Keck ZY, et al. Molecular cloning and disease association of hepatitis G virus: a transfusion-transmissible agent. Science 1996;271(5248):505–508. The authors describe the hepatitis G virus genomic structure, its association with acute and chronic hepatitis, and its global distribution. Tam AW, Smith MM, Guerra ME, et al. Hepatitis E virus (HEV): molecular cloning and sequencing of the full-length viral genome. Virology 1991;185(1):120–131. The authors reported on the cloning and nucleotide sequencing of an overlapping, contiguous set of cDNA clones representing the entire genome of the HEV Burma strain. Their findings suggested that the HEV was the prototype human pathogen for a new class of RNA virus.

References 1. Shapiro CN, Margolis HS. Worldwide epidemiology of hepatitis A virus infection. J Hepatol 1993;18(Suppl 2):S11–S14.

2. Shapiro CN, Coleman PJ, McQuillan GM, et al. Epidemiology of hepatitis A: seroepidemiology and risk groups in the USA. Vaccine 1992;10(Suppl 1):S59–S62.

3. Normann A, Graff J, Flehmig B. Detection of hepatitis A virus in a factor VIII preparation by antigen capture/PCR. Vox Sang 1994;67 (Suppl 1):57–60, (Discussion 1).

4. Cohen JI. Hepatitis A virus: insights from molecular biology. Hepatology 1989;9(6):889–895.

5. Kaplan G, Totsuka A, Thompson P, et al. Identification of a surface glycoprotein on African green monkey kidney cells as a receptor for hepatitis A virus. Embo J 1996;15(16):4282–4296.

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171. Limaye AP, Corey L, Koelle DM, et al. Emergence of ganciclovirresistant cytomegalovirus disease among recipients of solid-organ transplants. Lancet 2000;356(9230):645–649.

172. Rizell M, Olausson M, Friman S. PTLD in liver transplant recipients. Transplant Proc 2001;33(4):2455.

173. Razonable RR, Paya CV. The impact of human herpesvirus-6 and -7 infection on the outcome of liver transplantation. Liver Transpl 2002;8 (8):651–658.

174. DesJardin JA, Cho E, Supran S, et al. Association of human herpesvirus 6 reactivation with severe cytomegalovirus-associated disease in orthotopic liver transplant recipients. Clin Infect Dis 2001;33 (8):1358–1362.

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Copyright ©2007 Lippincott Williams & Wilkins > Table of Contents > Volume I > Section V - Viral Hepatitis > Chapter 27 Hepatitis A

Chapter 27 Hepatitis A Maria H. Sjögren

Key Concepts z

Hepatitis A is a worldwide infection whose epidemiology is changing as countries improve water sanitation and use other preventive methods such as immunization.

z

The precise mechanism of hepatic uptake in human liver is unknown and the cellular receptor for hepatitis A virus (HAV) has not been definitively identified; once infection occurs, HAV is distributed throughout the liver.

z

Infection with HAV does not result in chronic disease. Rarely, it can have a prolonged course or a relapsing course and occasionally, profound cholestasis can occur. Mortality rate is low in previously healthy persons. Morbidity can be significant in adults and older children.

z

Acute hepatitis A is clinically indistinguishable from other forms of viral hepatitis. A diagnosis of acute hepatitis A requires demonstration of immunoglobulin M (IgM) anti-HAV in serum.

z

Original recommendations in 1999 by the Advisory Committee on Immunization Practices (ACIP) had the overall strategy to immunize populations at risk. In 2005, the ACIP recommended that all children between 1 and 2 years of age receive the hepatitis A vaccine.

Experimental work in humans led to the clinical recognition that viruses were etiologic agents of hepatitis A (“infectious hepatitis”) and hepatitis B (“serum hepatitis”) (1,2). Later, the existence of two hepatitis viruses was demonstrated: Hepatitis A virus (HAV) and hepatitis B virus (HBV) (3). HAV was first characterized in 1973, when scientists detected the virus in stools from human volunteers who were infected with HAV (4). The ensuing development of sensitive and

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specific serologic assays for the diagnosis of HAV infection and the isolation of HAV in cell culture (5) were important advances that permitted the understanding of the epidemiology of HAV infection and, ultimately, control of the disease.

Virology In 1982, HAV was classified as an enterovirus type 72 belonging to the Picornaviridae family. Subsequent determination of the sequence of HAV nucleotides and amino acids led to questioning of this classification, and a new genus, hepatovirus, was created for HAV (6). HAV has an icosahedral shape and is a nonenveloped virus. It measures 27 to 28 nm in diameter, has a buoyant density of 1.33 to 1.34 g/cm (3) in cesium chloride, and has a sedimentation coefficient of 156 to 160S by ultracentrifugation. HAV survives exposure to ether and an acid environment at pH 3. It also survives heat exposure at 60 ° C for 60 minutes but is inactivated at 85 ° C for 1 minute. HAV is capable of surviving in seawater (4% survival rate), dried feces at room temperature for 4 weeks (17% survival), or live oysters for 5 days (12% survival) (7). Only one serotype of HAV is known, and there is no antigenic crossreactivity with the hepatitis B, C, D, E, or G agents. The HAV genome consists of a positive-sense ribonucleic acid (RNA) that is 7.48 kb long, single stranded, and linear. HAV RNA has a sedimentation coefficient of 32 to 33S and a molecular weight of P.730 2.8 × 10 4 . The HAV RNA has a long open reading frame of 6,681 nucleotides and is covalently linked to a 5′ terminal protein and a 3′ terminal polyadenosine tract. The onset of HAV replication in cell culture systems takes from weeks to months. Primate cells, including African green monkey kidney cells, primary human fibroblasts, human diploid cells (MRC-5), and fetal rhesus kidney cells, are favored for the cultivation of HAV in vitro. The virus is not cytopathic, and persistent infection in the cell cultures is the rule. Two conditions control the outcome of HAV replication in cell culture (8). First, the genetic make-up of the virus is important; HAV strains mutate in distinct regions of the viral genome as they become cell culture adapted. The second condition is the metabolic activity of the host cell at the time of infection. Cells in culture, although infected simultaneously, initiate HAV replication in an asynchronous manner. This asynchronicity may be caused by differences in the metabolic activity of individual cells, but there is no definitive evidence of cellcycle dependence of HAV replication (9). An initial step in the life cycle of a virus is its attachment to a cell surface receptor. The location and function of these receptors

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determine tissue tropism. Little is known about the mechanism of entry of HAV into cells. Some work has suggested that HAV could infect cells by a surrogate-receptor binding mechanism (by a nonspecified serum protein). HAV infectivity in tissue culture has been shown to require calcium and to be inhibited by the treatment of the cells with trypsin, phospholipases, and β-galactosidase (10). A surface glycoprotein, named HAVcr-1, on African green monkey kidney cells has been identified as a receptor for HAV. Blocking of HAVcr-1 with specific monoclonal antibodies prevents infection of otherwise susceptible cells. Experimental data suggest that HAVcr-1 not only serves as an attachment receptor but may also facilitate uncoating of HAV and its entry into hepatocytes (11). Whatever the entry mechanism, once HAV enters a cell, the viral RNA is uncoated, cell host ribosomes bind to viral RNA, and polysomes are formed. HAV is translated into a large polyprotein of 2,227 amino acids. This polyprotein is organized into three regions: P1, P2, and P3. The P1 region encodes the structural proteins VP1, VP2, VP3, and a putative VP4. The P2 and P3 regions encode nonstructural proteins associated with viral replication. The HAV RNA polymerase copies the plus RNA strand. The RNA transcript, in turn, is used for translation into proteins, which are used for assembly into mature virions. It appears that downregulation of HAV RNA synthesis occurs as defective HAV particles appear (12). In addition, a group of specific RNA-binding proteins have been observed during persistent infection (13). The origin and nature of these proteins is unknown, but they exert activity on the RNA template and are believed to play a regulatory role in the replication of HAV (14). Numerous strains of HAV exist, with considerable nucleotide sequence variability (15% to 25% difference within the P1 region of the genome). Human HAV strains can be grouped into four different genotypes (I, II, III, and VII), whereas simian strains of HAV belong to genotypes IV, V, and VI (15). Despite the nucleotide sequence heterogeneity, the antigenic structure of human HAV is highly conserved among strains. The HAV VP1/2A and 2C genes are thought to be responsible for viral virulence, on the basis of experiments in which recombinant HAV caused acute hepatitis in animals following the construction of 14 chimeric virus genomes from two infectious complementary deoxyribonucleic acid clones that encoded a virulent and an attenuated HAV isolate (HM175 strain) and the genotype and phenotype of each virus were compared (16). Among the many strains of HAV, the HM175 and CR326 human HAV strains are important because they are used for the production of commercially available vaccines. Strain HM175 was isolated in 1978,

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from the human feces of Australian patients in a small outbreak of hepatitis A. CR326 was isolated from Costa Rican patients infected with HAV. The nucleotide and amino acid sequences showed 95% identity between the two strains. Vaccines prepared from these strains are thought to provide protection against all relevant human strains of HAV. Variations in the HAV genome are thought to play a role in the development of fulminant hepatic failure (FHF) during acute HAV infection. The 5′ untranslated region of the HAV genome was sequenced in serum samples from 84 patients with HAV infection, including 12 with FHF (17). The investigators observed relatively fewer nucleotide substitutions in the HAV genome of patients with FHF than in those without FHF (P < 0.001). The differences were most prominent between nucleotides 200 and 500, suggesting that nucleotide variation in the central portion of the 5′ untranslated region influence the clinical severity of HAV infection.

Epidemiology Acute hepatitis A is a reportable infectious disease in the United States, with a rate of infection of 4/100,000 (18). In 2001, 10,616 cases of HAV infection were reported in the United States and in 2003, 7,653 cases of acute HAV infection were reported to the Center for Diseases Control and Prevention (CDC), the lowest number to date. Taking into consideration the underreporting of cases and the occurrence of asymptomatic infections, the true number of annual HAV infections P.731 has been calculated to be 93,000 and 61,000 for both years, respectively (19). The highest rate of reported disease is among children aged 5 to 14 years; 25% of reported cases are among persons aged 20 years or less (19), but HAV infection can occur in any agegroup. The epidemiologic risk factors for HAV infection reported for the US population in 2002 were as follows: Unknown, 57%; sexual or household contact with a patient who has hepatitis A, 12%; international travel, 9%; male homosexual activity, 8%; injection drug use, 5%; child or employee in a day-care center, 1%; food or waterborne outbreak, 1%; contact with a day-care child or employee, 3%; and other contact with a patient who has hepatitis, 4% (20). HAV infection generally follows one of three epidemiologic patterns (21). In countries where sanitary conditions are poor, most children are infected at an early age. Although earlier seroepidemiologic studies routinely showed that 100% of preschool children in these countries had detectable antibody to HAV (anti-HAV) in serum, presumably reflecting previous subclinical infection, subsequent studies have

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shown that the average age of infection has increased rapidly to 5 years and above, when symptomatic infection is more likely. For example, 82% of 1,393 Bolivian school children were shown to have detectable anti-HAV, but when they were stratified into two groups according to family income, a significant difference was found between the groups: 95% of children from low-income families had detectable anti-HAV as against 56% of children from high-income families (22). The second epidemiologic pattern is seen in industrialized countries, where the prevalence of HAV infection is low among children and young adults. In the United States, the prevalence of anti-HAV is approximately 10% in children but 37% in adults (23). The third epidemiologic pattern is observed in closed or semiclosed communities, such as some isolated communities in the South Pacific, where HAV is capable (through epidemics) of infecting the entire population, which then becomes immune. Thereafter, newborns remain susceptible until the virus is reintroduced into the community.

Table 27.1. Detection of Hav and Infectivity of Human Secretions or Excretions

Secretion/excretion Stool

Comment Main source of

References (28,29)

infection. HAV is detectable during incubation period and for several weeks after the onset of disease. After the onset of symptoms, HAV is detectable in 45% and 11% of fecal specimens from first and second week, respectively, whereas HAV ribonucleic acid (by a polymerase chain reaction assay) is detectable for 4 to 5 mo.

Blood

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Viremia is present

(30,31)

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during incubation period. Blood collected 3 and 11 days before the onset of symptoms caused posttransfusion infection in donors. Chronic viremia does not occur.

Bile

HAV has been detected

(32)

in the bile of chimpanzees infected with HAV.

Urine

HAV is detected in low

(33,34)

titer during the viremic phase. A urine sample infected 1 of 12 subjects after oral inoculation. Urine contaminated with blood was also infectious.

Nasopharyngeal

Unknown in humans.

(35)

HAV has been identified in the oropharynx of experimentally infected chimpanzees.

Semen, vaginal fluid

Uncertain. HAV may be

(36)

detectable during viremic phase.

HAV, hepatitis A virus.

Whatever the epidemiologic pattern, the primary route of transmission of HAV is the fecal–oral route, by either person-to-person contact or ingestion of contaminated food or water. Although rare, transmission of HAV by a parenteral route has been documented following blood transfusion (24,25) or use of blood products (26). Cyclic outbreaks

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among users of injection and noninjection drugs and among men who have sex with men (up to 10% may become infected in outbreak years) have been reported (27). Table 27.1 provides information about the detection of HAV and its infectivity in human body fluids (28,29,30,31,32,33,34,35,36). Approximately 11% to 22% of patients with acute hepatitis A require hospitalization, with an average cost of $6,914 per patient (37). In one outbreak involving 43 persons, the total cost was approximately $800,000. On average, 27 workdays are lost per adult case of hepatitis A, with a total loss of 829,000 workdays/year in the United States. Combined direct and indirect costs associated with HAV infection in the United States totaled more than $200 million in 1989 and approximately $488.8 million in 1997 (27,37).

Pathogenesis Once HAV is ingested and survives gastric acid, it traverses the small intestine mucosa and reaches the liver through the portal vein. The precise mechanism of hepatic uptake in humans is unknown (see preceding text). In an experimental model on African green monkey kidney cells (11), the putative cellular receptor for HAV has been identified as a surface glycoprotein. P.732 Once the virus reaches the hepatocyte, it starts replicating in the cytoplasm, where it is seen on electron microscopy as a fine granular pattern, but it is not present in the nucleus. HAV is distributed throughout the liver. Although HAV antigen has been detected in other organs (lymph nodes, spleen, kidney), the virus appears to replicate exclusively in hepatocytes. Once the virus is mature, it reaches the systemic circulation through the hepatic sinusoids and is released into the biliary tree through the bile canaliculi, passed into the small intestine, and eventually excreted in the feces. The pathogenesis of HAV-associated hepatocyte injury is not completely defined. The lack of injury to cells in cell culture systems suggests that HAV is not cytopathic. Immunologically mediated cell damage is more likely. The emergence of anti-HAV could result in hepatic necrosis during the immunologically mediated elimination of HAV.

Clinical Features Infection with HAV does not result in chronic disease, but in an acute self-limited episode of hepatitis. Rarely, acute hepatitis A can have a prolonged or a relapsing course, and occasionally profound cholestasis can occur. Commonly, the incubation period is 2 to 4 weeks, rarely up to 6 weeks. The mortality rate is low in previously healthy persons.

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Morbidity can be significant in adults and older children. The clinical characteristics of cases of hepatitis A reported in 2002 were similar to those in previous years with a preponderance of cases in men of all age-groups. Overall, 72% of patients manifested jaundice, 25% required hospitalization, and 0.5% died (26). The need for hospitalization increased with age, from 5% among children older than 5 years of age to 34% among persons 60 years of age or older. HAV infection usually presents in one of five different clinical patterns: (i) Asymptomatic without jaundice; (ii) symptomatic with jaundice and self-limited to approximately 8 weeks; (iii) cholestatic, with jaundice lasting 10 weeks or more; (iv) relapsing, with two or more bouts of acute HAV infection occurring over a 6- to 10-week period; and (v) FHF. Children older than 2 years of age are usually asymptomatic; jaundice develops in only 20%, whereas symptoms develop in most children (80%) aged 5 years or older. A high rate of symptoms occurs in adolescents and adults. HAV infection with prolonged cholestasis is a rare variant but occasionally leads to invasive diagnostic procedures (inappropriately), because the diagnosis of acute hepatitis may not be readily accepted in patients with jaundice for several months, even in the presence of detectable anti-HAV of the immunoglobulin M (IgM) class (see the following sections) (38). A relapsing course is observed in approximately 10% of patients with acute hepatitis A. Shedding of HAV in stool has been documented during the relapse phase (39). This variant is benign, and the infection ultimately resolves (39). Neither the cholestatic variant nor the relapsing hepatitis A is associated with increased mortality. In all cases, treatment is symptomatic. Acute hepatitis A, unlike hepatitis E, is not associated with an increased mortality rate in pregnant women. Prodromal symptoms in patients with acute hepatitis A include fatigue, weakness, anorexia, nausea, vomiting, and abdominal pain. Less common symptoms include fever, headache, arthralgias, myalgias, and diarrhea. Dark urine precedes other symptoms in approximately 90% of infected persons; this symptom occurs within 1 to 2 weeks of the onset of prodromal symptoms. Symptoms of hepatitis may last from a few days to 2 weeks and usually decrease with the onset of clinical jaundice. Right upper quadrant tenderness and mild liver enlargement are present on physical examination in 85% of patients; splenomegaly and cervical lymphadenopathy are each present in 15%. Complete clinical recovery is achieved in 60% of affected persons within 2 months and in almost everyone by 6 months. The overall prognosis of acute hepatitis A in otherwise healthy adults is excellent. Potentially fatal complications (e.g., FHF) develop in a few patients (see later sections).

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Acute HAV infection must be differentiated from other causes of acute viral hepatitis, autoimmune hepatitis (AIH), and other causes of acute hepatitis by appropriate serologic testing (see Chapters 29 and 30). However, in some cases the diagnosis may be difficult to make because the patient may harbor more than one viral infection, such as chronic hepatitis B or chronic hepatitis C, with superimposed acute HAV infection.

Fulminant Hepatitis A FHF caused by HAV is rarely seen in children, adolescents, or young adults. However, the case-fatality rate in people over 49 years of age with acute hepatitis A is reported to be 1.8%, compared with an overall rate of 0.3% in persons of all ages (39). Hepatic failure caused by hepatitis A becomes manifest in the first week of illness in approximately 55% of affected patients and during the first 4 weeks in 90%; FHF is rarely seen after 4 weeks (40). The contribution of HAV to acute liver failure has been reported to be increased in populations classified as hyperendemic for HAV. In a report from India, where 276 patients with FHF were seen between 1994 and 1997, 10.6% of the cases among adults were caused by HAV. HAV had been responsible for only 3.5% of cases among 206 patients with FHF seen in the same community from 1978 to 1981 (41). P.733 Certain populations have increased morbidity and a high risk of acute liver failure from HAV infection. Among these groups are the elderly (42) and persons with chronic liver disease. A 1998 report described the clinical outcome of 256 persons hospitalized for acute hepatitis A in Tennessee from January 1994 through December 1995 (43). On admission, 89% had experienced prolonged nausea or vomiting and 26% had a prolonged prothrombin time (>3 seconds); 39 had serious complications (19 were hepatobiliary in nature and 20 were extrahepatic complications), and 5 (2%) died. Morbidity and mortality correlated with age. Twenty-five percent of patients aged 40 and above had at least one complication, as compared with 11% of patients younger than 40 years of age (P = 0.014). Although two reports since the late 1990s have described a decline in the number of cases of acute viral hepatitis among patients with FHF in the United States (44,45), this decline is attributable principally to the control of hepatitis B. The contribution of HAV infection to FHF has remained unchanged since the 1970s, despite the availability of highly efficacious vaccines.

Autoimmune Disease Following Acute Hepatitis A

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Several viruses have been reported to trigger the onset of AIH. In rare cases, hepatitis A has been followed by the development of type 1 AIH. Genetic predisposition is thought to play a role (46,47).

Diagnosis Acute hepatitis A is clinically indistinguishable from other forms of viral hepatitis. The diagnosis of infection is based on the detection of specific antibodies against HAV (anti-HAV) in serum. A diagnosis of acute hepatitis A requires demonstration of IgM anti-HAV in serum. The test is positive from the onset of symptoms (48) and usually remains positive for approximately 4 months (49). Some patients may have low levels of detectable IgM anti-HAV for more than 1 year after the initial infection (48). IgG anti-HAV is also detectable at the onset of the disease, remains present usually for life, and, following clinical recovery, is interpreted as a marker of previous HAV infection. Testing for HAV RNA is limited to research laboratories. HAV RNA has been detected in serum, stool, and liver tissue. Viral RNA can be amplified by polymerase chain reaction (PCR) methodology (26). With a PCR assay, HAV RNA has been documented in human sera for up to 21 days after the onset of illness (50). The use of hepatitis C virus (HCV) RNA testing has been described in a report of 76 French patients with acute HAV infection seen between January 1987 and April 2000; 19 of them had FHF (51). Ten patients required liver transplantation, and one patient died while awaiting liver transplantation. The HAV RNA status was determined in 39 of the 50 patients in whom sera and clinical data were available, including the 19 with FHF. HAV RNA was detected in 36 of these 50 patients (72%). The likelihood that HAV RNA was undetectable was greater in patients with FHF than in those with nonfulminant hepatitis (P < 0.02). When HAV RNA was detectable, titers were lower in patients with encephalopathy than in patients with nonfulminant hepatitis (3.6 log vs. 4.4 log, P = 0.02). These data suggest that the detection of IgM anti-HAV and undetectable or lowtiter HAV RNA in patients with severe acute hepatitis may signal an ominous prognosis and the need for early referral for liver transplantation. As in other studies, HAV genotype did not seem to play a role in the severity of clinical manifestations (52).

Prevention and Treatment Recommendations concerning immunoprophylaxis of HAV were published in December 1999 by the Advisory Committee on Immunization Practices (ACIP) (27). The overall strategy is to protect persons from disease and to lower the incidence of HAV infection in the United States. The available vaccines are not licensed for use in children less than 1 year of age. Currently, all children should receive hepatitis A vaccine at age 1 year or older (52a), high-risk populations

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are targeted for immunization; Table 27.2 lists these populations. Because children who reside in high-risk areas are targeted for vaccination, the overall rate of HAV infection has declined steadily, and in 2002, it was 3.1/100,000, the lowest rate yet recorded. The decline in rates has been greater among children than adults and in states where routine childhood vaccination is recommended, P.734 suggesting that childhood vaccination has had a positive impact. Hepatitis rates declined 20-fold during the years 1997 to 2001 among American Indian and Alaska Native children where routine hepatitis A vaccine was implemented (53).

Table 27.2. Groups at High Risk of Hepatitis A Virus Infection

Healthy persons who travel to endemic areas, work in occupations for which the likelihood of exposure is high, are family members of infected patients, or adopt infants or children from endemic areas Persons with chronic liver disease Human immunodeficiency virus–positive patients Men who have sex with men Users of injection and noninjection illicit drugs Persons with clotting factor disorders Persons who live in communities with high or intermediate rates of HAV infection Children who live in areas where the rate of HAV infection is at least twice the national average (≥20 cases/100,000 population)

HAV, hepatitis A virus.

However, a 2003 CDC analysis of hepatitis A vaccination coverage for children aged 24 to 35 months, who reside in the 11 states where the HAV vaccine is routinely recommended, showed that immunization ranged from 6.4% to 72.7% with an average of 50.9%, whereas immunization among children of the same age residing in the six states where HAV vaccination should be considered averaged 25% (range 0.6% to 32.3%). The analysis concluded that HAV immunization rates for children aged 24 to 35 months are lower than the overall rates for other children vaccines (54). It is likely that universal immunization was not recommended in the United States because communities were considered to have high, intermediate, and low rates of hepatitis A and US government

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surveillance data demonstrated that communities with high and intermediate rates were primarily responsible for an average of 50% of reported HAV cases each year (27). Hence, the recommendation was based on the concept that reducing the incidence of hepatitis A in states with high or intermediate average annual incidence of hepatitis A (Table 27.1) through routine vaccination of children would substantially reduce the incidence of the national disease. However, recent outbreaks in Georgia, Tennessee, and Pennsylvania where more than 600 symptomatic cases and three deaths were reported and thousands of exposed individuals required immediate passive immunization (55) seems to contradict the recommendation for immunization for high or intermediate rates of endemic HAV and it is likely that immunization directed to specific groups would not control the infection as efficiently as universal immunization would do. In October 2005, the CDC advisory committee recommended that all children in the United States receive the vaccine; therefore, it is expected that all children between the age of 1 and 2 years would have the HAV vaccine integrated into their childhood immunization programs (CDC press release October 28, 2005).

Table 27.3. Recommended Regimens for Hepatitis A Vaccination a

Dosing Volume

schedule

(mL)

(mo)

720 EL.U.

0.5

0, 6–12

>18

1440 EL.U.

1.0

0, 6–12

2–

25 U

0.5

0, 6–18

>18

50 U

1.0

0, 6–18

≥18

720 EL.U.

1.0

0, 1, 6

Age Vaccine Havrix

(y) 2–

Dose

18

Vaqta

18

Twinrix

hepatitis A virus

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20 µg hepatitis B virus

a

Vaccines are injected intramuscularly in the deltoid area.

EL.U., enzyme-linked immunosorbent assay (ELISA) units.

There are no specific medications to treat acute hepatitis A; symptomatic treatment is the rule. Attention to sanitation and administration of serum Ig are the mainstays of preventing HAV infection. The availability of excellent HAV vaccines has rendered the use of Ig for pre-exposure prophylaxis unnecessary. When Ig is used for postexposure prophylaxis, it should be given within 2 weeks of exposure. In these cases, the recommended dose is 0.02 mL/kg by intramuscular injection. Although considered safe, Ig can cause fever, myalgias, and pain at the injection site. Postexposure prophylaxis with Ig can be accompanied safely with the initiation of active immunization with the vaccine (56). The HAV vaccine was first licensed in the United States in 1995; two inactivated HAV vaccines are commercially available. Extensive use of the vaccines in clinical trials and postmarketing surveillance support the safety and efficacy of these products. Havrix is manufactured by SmithKline Biologicals, Rixensart, Belgium, and Vaqta, by Merck Sharp & Dohme, West Point, Pennsylvania. Both vaccines are derived from HAV grown in cell culture. The final products are purified and formalin inactivated; they contain alum as an adjuvant. The basic difference between the two commercially available vaccines is the HAV strain used for preparation. Havrix was prepared with the HM175 strain, whereas Vaqta was prepared with the CR326 strain (56,57); the difference is of little practical importance, because both vaccines are safe and immunogenic. The doses and schedule of immunization are shown in Table 27.3. Following vaccination with Havrix, anti-HAV is estimated to remain detectable in serum for approximately 20 years; immunity may last longer (58). From the time the HAV vaccine was licensed in the United States through 1998, more than 6.5 million doses were administered, including 2.3 million pediatric doses. Worldwide, more than 65 million doses of HAV vaccine were administered through 1999. Among adults,

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the most frequent local side effects were soreness at the injection site (56%), headache (14%), and malaise (7%). In children, the most frequent side effects were soreness at the injection site (15%), P.735 feeding problems (8%), headache (4%), and injection site induration (4%). In the United States, through 1998, the national Vaccine Adverse Event Reporting System received 247 reports of unexplained adverse events within 6 weeks of immunization. Approximately one third of these reports occurred with concurrent vaccinations and could not be attributed to the HAV vaccine. Thirteen events in children (0.6/100,000 doses distributed) and 85 events in adults (1.4/100,000 doses distributed) were considered serious. These events included neurologic, hematologic, and autoimmune syndromes. However, no reported serious event could be attributed definitively to the HAV vaccine, and the reported rates did not exceed the expected background rates. For example, the incidence of the Guillain-Barré syndrome ranges from 0.5 to 2.4 cases/100,000 person-years, and the 5 cases of Guillain-Barré syndrome among adult HAV vaccine recipients represented an incidence of 0.2 cases/100,000 person-years (27). Postmarketing reports have not shown a higher incidence rate in vaccine recipients. A combined formulation of hepatitis A and B vaccines (Twinrix) is available and has an excellent record of efficacy and safety (59). The dosing schedule is shown in Table 27.3.

Immunization Against Hepatitis A Virus in Patients with Chronic Liver Disease Persons with chronic liver disease are at increased risk of HAV-related morbidity and mortality if they acquire the infection. Therefore, preexposure prophylaxis with the HAV vaccine has been recommended for patients with chronic liver disease who are susceptible to HAV (60). This recommendation should be extended to pre- and post–liver transplant recipients, although the immunogenicity of the HAV vaccine is reduced in these persons (61,62). An episode of acute hepatitis in a patient with underlying chronic liver disease poses the risk of considerable morbidity and mortality. Although the current guidelines recommend immunization against HAV for all patients with chronic liver disease (27), the results of several cost-effective analyses have been conflicting. A report published in 2000 found that saving the life of one patient with HCV infection by HAV vaccination would cost 23 million Canadian dollars (63). However, some of the assumptions in this report have been challenged (64). Two other studies of patients with chronic hepatitis C showed a decided benefit to immunization against HAV (65). The methods used in these studies were dissimilar, and some analyses may have been insensitive

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to the incidence of HAV or may have underestimated the economic and societal costs of a case of FHF. Universal immunization against HAV during childhood, before the possible occurrence of chronic liver disease, offers the promise of preventing HAV infection (66).

Annotated References Center for Diseases Control and Prevention (CDC). Prevention of hepatitis A through active or passive immunization: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR, 1999:48(RR–12):1–37. Original recommendations in 1999 by the Advisory Committee on Immunization Practices (ACIP) had the overall strategy to immunize populations at risk. In 2005, the ACIP recommended that all children between 1 and 2 years of age receive hepatitis A vaccine. Feinstone SM, Kapikian AZ, Purcell RH, et al. Hepatitis A: detection by immune electron microscopy of a virus like antigen associated with acute illness. Science 1973;182:1026–1028. Description of the discovery of the hepatitis A virus. Gordon SC, Reddy KR, Schiff ER. Prolonged intrahepatic cholestasis secondary to acute hepatitis A. Ann Intern Med 1984;101:635–637. Report of unusual clinical manifestations of acute HAV infection that result in unnecessary interventions if not accurately diagnosed. Provost PJ, Hilleman MR. An inactivated hepatitis A virus vaccine prepared from infected marmoset liver. Proc Soc Exp Biol Med 1978;159:201–203. Initial successful report on the possibility of producing a hepatitis A vaccine. Willner IR, Mark DU, Howard SC et al. Serious hepatitis A: an analysis of patients hospitalized during an urban epidemic in the United States. Ann Inter Med 1998;128:111–114. Although HAV infection does not produce chronic liver disease, morbidity and mortality can be considerable.

References 1. MacCallum FO, McFarlan AM, Miles JAR, et al., eds. Infective

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hepatitis: studies in East Anglia during the period 1943–1947. Medical Research Council, Special Report No. 273, London: HMSO, 1951.

2. Havens WP, Paul JR. Infectious hepatitis and serum hepatitis. In: Rivers TM, Horsfall F, eds. Viral and rickettsial infections of man, 3rd ed, Vol. 261. Philadelphia: JB Lippincott, 1959:729–734.

3. Krugman S, Ward R, Giles JP, et al. Infectious hepatitis: detection of virus during the incubation period and in clinically inapparent infections. N Engl J Med 1959;261:729–734.

4. Feinstone SM, Kapikian AZ, Purcell RH. Hepatitis a: detection by immune electron microscopy of a viruslike antigen associated with acute illness. Science 1973;182:1026–1028.

5. Provost PJ, Hilleman MR. An inactivated hepatitis A virus vaccine prepared from infected marmoset liver. Proc Soc Exp Biol Med 1978;159:201–203.

6. Minor PD. Picornaviridae. Classification and nomenclature of viruses. Fifth report of the International Committee on Taxonomy of Viruses. Arch Virol Suppl 1991;2:320–326.

7. Sobsey MD, Shields PA, Hauchman FS, et al. Survival and persistence of hepatitis A virus in environmental samples. In: Zuckerman AJ, ed. Viral hepatitis and liver disease. New York: Alan R. Liss, 1988:121–124.

8. Siegl G. Replication of hepatitis A virus and processing of proteins. Vaccine 1992;10:S32–S35.

9. Harmon SA, Summers DF, Ehrenfeld E. Detection of hepatitis A virus RNA and capsid antigen in individual cells. Virus Res 1989;12:361–369.

10. Seganti L, Superti F, Orsi N, et al. Study of the chemical nature of Frp/3 cell recognition units for hepatitis A virus. Med Microbiol Immunol 1987;176:21–26. P.736

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12. Siegl G, Nüesch JPF, de Chastonay J. DI-particles of hepatitis A virus in cell culture and clinical specimens. In: Brinton MA, Heinz FX, eds. New aspects of positive strand RNA viruses. Washington: American Society for Microbiology, 1990:102–107.

13. Nüesch JPF, Weitz M, Siegl G. Proteins specifically binding to the 3′ untranslated region of hepatitis A virus RNA in persistently infected cells. Arch Virol 1993;128:65–79.

14. Robertson BH, Jansen RW, Khanna B, et al. Genetic relatedness of hepatitis A virus strains recovered from different geographic regions. J Gen Virol 1992;73:1365–1377.

15. Mathiesen LR, Feinstone SM, Purcell RH, et al. Detection of hepatitis A antigen by immunofluorescence. Infect Immun 1977;18:524–530.

16. Emerson SU, Huang YK, Nguyen H, et al. Identification of VP1/2A and 2C as a virulence genes of hepatitis A virus and demonstration of genetic instability of 2C. J Virol 2002;76:8551– 8559.

17. Fujiwara K, Yokosuka O, Ehata T, et al. Association between severity of type A hepatitis and nucleotide variations in the 5′ nontranslated region of hepatitis A virus RNA: strains from fulminant hepatitis have fewer nucleotide substitutions. Gut 2002;51:82–88.

18. Center for Diseases Control and Prevention (CDC). Summary of notifiable diseases United States 2001. MMWR 2001;50(53):1–108.

19. Centers for Diseases Control and Prevention (CDC). Guidelines for viral hepatitis surveillance and case management, Atlanta, GA: 2004:1–47.

20. Center for Diseases Control and Prevention (CDC). Hepatitis surveillance report no. 59, Atlanta, GA: 2004:1–60.

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21. Gust ID. Epidemiological patterns of hepatitis A in different parts of the world. Vaccine 1992;10:S56–S58.

22. Gandolfo GM, Ferri GM, Conti L, et al. Prevalence of infections by hepatitis A, B, C and E viruses in two different socioeconomic groups of children from Santa Cruz, Bolivia. Med Clin (Barc) 2003;120:725–727.

23. Centers for Disease Control and Prevention (CDC). Prevention of hepatitis A through active or passive immunization: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR 1996;45(RR-15):1–30.

24. Skidmore SJ, Boxall EH, Ala F. A case report of posttransfusion hepatitis A. J Med Virol 1982;10:223.

25. Hollinger FB, Khan NC, Oefinger PE, et al. Posttransfusion hepatitis type A. JAMA 1983;250:2313–2317.

26. Mannucci PM, Gdovin S, Gringeri A, et al. Transmission of hepatitis A to patients with hemophilia by Factor VIII concentrates treated with organic solvent and detergent to inactivate viruses. Ann Int Med 1994;120:1–7.

27. Prevention of hepatitis A through active or passive immunization: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR 1999:48(RR-12):1–37.

28. Coulepis AG, Locarnini SA, Lehmann NI, et al. Detection of HAV in feces. J Infect Dis 1980;141:151–156.

29. Rosenblum LS, Villarino ME, Nainan OV, et al. Hepatitis A outbreak in a neonatal intensive care unit: risk factors for transmission and evidence of prolonged viral excretion among preterm infants. J Infect Dis 1991;164:476–482.

30. Francis T Jr, Frisch AW, Quilligan JJ. Demonstration of infectious hepatitis virus in presymptomatic period after transfer by transfusion. Proc Soc Exp Biol Med 1946;61:276–280.

31. Harden AG, Barondess JA, Parker B. Transmission of infectious

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hepatitis by transfusion of whole blood. N Engl J Med 1955;253:923–925.

32. Schulman AN, Dienstag JL, Jackson DR, et al. Hepatitis A antigen particles in liver, bile and stool of chimpanzees. J Infect Dis 1976;134:80–84.

33. Giles JP, Liebhaber H, Krugman S, et al. Early viremia and viruria in infectious hepatitis. Virology 1964;24:107–108.

34. Findlay GM. Infective hepatitis in West Africa: 1. Mon Bull Ministry Health 1948;7:2–11.

35. Cohen JI, Feinstone S, Purcell RH. Hepatitis A virus infection in a chimpanzee: duration of viremia and detection of virus in saliva and throat swabs. J Infect Dia 1989;160:887–890.

36. Berge JJ, Drennan D, Jacobs J, et al. The cost of hepatitis A infections in American adolescents and adults in 1997. Hepatology 2000;31:469–473.

37. Gordon SC, Reddy KR, Schiff ER. Prolonged intrahepatic cholestasis secondary to acute hepatitis A. Ann Intern Med 1984;101:635–637.

38. Sjogren MH, Tanno H, Fay O, et al. Hepatitis A virus in stool during clinical relapse. Ann Intern Med 1987;106:221–226.

39. William R. Classification, etiology and considerations of outcome in acute liver failure. Semin Liver Dis 1996;16:343–348.

40. Chadha MS, Walimbe AM, Chobe LP, et al. Comparison of etiology of sporadic acute and fulminant viral hepatitis in hospitalized patients in Pune, India during 1978–81 and 1994–97. Indian J Gastroenterol 2003;22(1):11–15.

41. Brown GR, Persley K. Hepatitis A epidemic in the elderly. South Med J 2002;95:826–833.

42. Willner IR, Mark DU, Howard SC, et al. Serious hepatitis a: an analysis of patients hospitalized during an urban epidemic in the

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United States. Ann Inter Med 1998;128:111–114.

43. Ostapowicz G, Fontana R, Schiedt FV, et al. Results of a prospective study of acute liver failure at 17 tertiary care centers in the United States. Ann Intern Med 2002;137:947–954.

44. Schiodt FV, Atillasoy E, Shakill AO, et al. Etiology and outcome for 295 patients with acute liver failure in the United States. Liver Transpl Surg 1999;5:29–34.

45. Vento S, Cainelli F. Is there a role for viruses triggering autoimmune hepatitis? Autoimmun Rev 2004;3:61–69.

46. Tagle Arrospide M, Leon Barua R. Viral hepatitis A as a triggering agent of autoimmune hepatitis report of a case and review of literature. Rev Gastroenterol Peru 2003;23:134–137.

47. Liaw YF, Yang CY, Chu CM, et al. Appearance and persistence of hepatitis A IgM antibody in acute clinical hepatitis A observed in an outbreak. Infection 1986;14:156–158.

48. Kao HW, Ashcavai M, Redeker AG. The persistence of hepatitis A IgM antibody after acute clinical hepatitis A. Hepatology 1984;4:933–936.

49. Yotsuyanagi H, Iino S, Koike K, et al. Duration of viremia in human hepatitis A viral infection as determined by polymerase chain reaction. J Med Virol 1993;40:35–38.

50. Rezende G, Roque-Alsonso M, Samuel D, et al. Viral and clinical factors associated with fulminant course of hepatitis A infection. Hepatology 2003;38:613–618.

51. Fujiwara K, Yokosuka O, Imazeki F, et al. Analysis of the genotype-determining region of hepatitis A viral RNA in relation to disease severities. Hepatol Res 2003;25:124–134.

52. Leentvaar-Kuijpers A, Coutinho RA, Brulein V, et al. Simultaneous passive and active immunization against hepatitis A. Vaccine 1992;10:S138–S141.

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54. Center for Diseases Control and Prevention (CDC). Hepatitis A vaccination coverage among children aged 24–35 months-United Sates. MMWR 2005;54(6):141–144.

55. Sjogren MH. The clinical profile of acute hepatitis A infection: is it really so severe? (reply). Hepatology 2004;39:572–573.

56. Andre FE, D'Hondt E, Delem A, et al. Clinical assessment of the safety and efficacy of an inactivated hepatitis A vaccine. Vaccine 1992;10 (Suppl 1):S160–S168.

57. Provost PJ, Hughes JN, Miller WJ, et al. An inactivated hepatitis A viral vaccine of cell culture origin. J Med Virol 1986;19:23–31.

58. Van Damme P, Thoelen S, Cramm K, et al. Inactivated hepatitis A vaccine: reactogenicity, immunogenicity, and long-term antibody persistence. J Med Virol 1994;44:446–451.

59. FDA approval for a combined hepatitis A and B vaccine. MMWR September 21, 2001/50 (37):806–807.

60. Reiss G, Keefe EB. Review article: hepatitis vaccination in patients with chronic liver disease. Aliment Pharmacol Ther 2004;19:715–727.

61. Aeslan M, Wiesner RH, Poterucha JJ, et al. Safety and efficacy of hepatitis A vaccination in liver transplantation recipients. Transplantation 2001;72:272–276.

62. Myers RP, Gregor JC, Marotta P. The cost-effectiveness of hepatitis A vaccination in patients with chronic hepatitis C.

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63. Jacobs RJ, Koff, RS. Cost-effectiveness of hepatitis A vaccination in patients with chronic hepatitis C. Hepatology 2000;32:873–874.

64. Jacobs RJ, Koff RS, Meyerhoff AS. The cost-effectiveness of vaccinating chronic hepatitis C patients against hepatitis A Am J Gastroenterol 2002;97:427–434.

65. Arguedas MR, Heudebert GR, Fallon MB, et al. The costeffectiveness of hepatitis A vaccination in patients with chronic hepatitis C viral infection in the United States. Am J Gastroenterol 2002;97:721–728.

66. Rosenthal P. Cost-effectiveness of hepatitis A vaccination in children, adolescents and adults. Hepatology 2003;37:44–51.

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Copyright ©2007 Lippincott Williams & Wilkins > Table of Contents > Volume I > Section V - Viral Hepatitis > Chapter 28 Hepatitis E

Chapter 28 Hepatitis E Maria H. Sjögren

Key Concepts z

Hepatitis E virus (HEV) infects humans by causing outbreaks of hepatitis or being the source of sporadic self-contained infections.

z

Antibody to hepatitis E has been observed in many areas of the world; in the United States, 1% to 5% of healthy blood donors have detectable anti-HEV.

z

Histopathologic features of HEV infection in the human liver include necroinflammatory processes and cholestatic hepatitis.

z

The clinical features of HEV are difficult to differentiate from other viral hepatitis, the diagnosis needs to be suspected and corroborated with serologic tests.

z

Case fatality rates among HEV-infected pregnant women have been reported to be between 15% and 25%.

z

Development of a hepatitis E vaccine has successfully completed a phase III trial.

After hepatitis A and hepatitis B were diagnosed with the aid of accurate serologic testing, it became apparent that at least two non-A, non-B infectious agents existed, one similar to hepatitis B, mainly transmitted parenterally, and another similar to hepatitis A, transmitted by the fecal–oral route and without sequelae of chronic liver disease. In the 1980s, two seminal discoveries correctly identified the first one as hepatitis C (1) and the second one became known as hepatitis E (2). Since then, hepatitis E has been recognized as the agent responsible for enterically transmitted non-A, non-B hepatitis. Research to understand the epidemiology, viral characteristics, and immunity against this viral agent was galvanized by the work of Balayan et al.

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(2) and in recent years by cloning the virus (3), which allowed the development of assays not only to diagnose the infection but also to better understand its epidemiology and develop vaccine candidates.

Virology Hepatitis E virus (HEV) was first visualized in 1983 when it was transmitted to a human volunteer and subsequently to an experimental animal model, thereby establishing its role as the etiologic agent of hepatitis E (2). HEV is a spherical nonenveloped virus 32 to 34 nm in size with spikes and indentations on its surface. It was recently classified into the separate genus Hepatitis E–like viruses (4). The genome of the virus is a single positive-stranded polyadenylated ribonucleic acid (RNA) of approximately 7.5/kb. It consists of three overlapping open reading frames (ORFs) and short untranslated regions at the 5′ and 3′ termini. ORF1 is located at the 5′ end and consists of the nonstructural genes while the 3′ end ORF2 represents one or more structural or capsid proteins. ORF2 contains important epitopes that can induce neutralizing antibodies P.740 and is the prime genomic area selected for vaccine development (4). The function of ORF3 has not been elucidated.

Table 28.1. Hepatitis E Virus Genotypes (4)

Genotypes Genotype 1

Isolates Southeast Asia (e.g., Burmese, Indian) North and Central Asia (e.g., China, Pakistan, Kyrgyzstan, India)

North Africa

Genotype 2

North America (Mexico)

Genotype 3

The United States

(humans and swine)

Genotype 4

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Subset of isolates from China and Taiwan

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Heterogeneous

Europe, Argentina

Although there is no consensus on genotype classification, it is generally accepted that on the basis of viruses having nucleotide divergence of not more than 20% of the nucleotides in the ORF2 region, four major HEV genotypes exist (Table 28.1). In addition, genetically heterogeneous isolates from several European countries have been designated as new genotypes, but this concept is not widely accepted; similarly, two novel HEV genotypes have been described from Argentina (4). Despite the diversity of HEV genotype, it is accepted that HEV exists as a single serotype (5), a concept that has important implications in vaccine development because it makes the development of a broadly protective vaccine possible. In 1990 the genome of HEV was cloned from infectious experimental animal bile. These experiments established that the clone ET1.1 represented a genuine portion of the HEV genome (3). Such advances permitted the development of sensitive and accurate assays that allow the diagnosis of the infection, the better understanding of its epidemiology, and development of candidate vaccines.

Epidemiology HEV appears to infect humans by causing outbreaks of hepatitis or by being the source of sporadic self-contained infections. Although the hepatitis E outbreaks are newsworthy, anti-HEV has been detected in many areas of the world, including industrialized countries, where no defined epidemics have been reported, for example, in the United States 1% to 5% of healthy blood donors have detectable anti-HEV (6). The meaning of such a high prevalence is still a source of controversy. In addition to representing true HEV infection, some scientists attribute the high prevalence to the nonspecificity of the serologic assays, whereas others believe that it may be a cross-reaction with another agent. The massive waterborne outbreaks of acute hepatitis in New Delhi in the 1955 to 1956 period (7) were diagnosed as “classical”

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waterborne hepatitis A. However, serologic testing of the available specimens in 1980 ruled out acute hepatitis A or acute hepatitis B and allowed the recognition of the infection as non-A, non-B hepatitis (8). Since then at least 17 HEV outbreaks have occurred in India (9) and more than 50 in Asia, Africa, and the American continents (4). In 1975, sporadic cases from Costa Rica were reported in which the illnesses were neither hepatitis A nor hepatitis B (10). In 1986 and 1987, outbreaks of acute hepatitis occurred in two rural villages located 70 miles south of Mexico City; 223 cases were diagnosed as non-A, non-B hepatitis, and stool samples from some cases yielded viral particles 32 to 34 nm in size, similar to the enterically transmitted non-A, non-B hepatitis from Asia (11). Hepatitis E has been detected among US travelers to endemic regions (12). However, a unique HEV whose genome is significantly different from the Burmese or Mexican strains has been described in the United States in humans and swine (13). In 2004, approximately 4,000 suspected cases of hepatitis E were reported by health clinics in Darfur, Sudan. Thousands of possible cases were also reported among refugees in Chad and Iraq (14). Hepatitis E is not an uncommon disease in many areas of the world, and it is recognized as a frequent cause of sporadic hepatitis in Asia. Some species of animals (rodents, swine, monkeys, etc.) have been found to have detectable anti-HEV (15), raising the possibility of HEV being a zoonotic disease that can be acquired from animals; however, there is no confirmation of such transmission.

Pathogenesis At least two human volunteers and studies in animal models have permitted the characterization of the pathogenesis of HEV. In the human volunteers, abnormal levels of aminotransferases were detected 4 to 5 weeks after ingestion of contaminated material and they remained abnormal for 1 to 3 months (2,16). Viral particles were excreted in stool approximately 4 weeks after ingestion of the inoculum, and the shedding lasted approximately 2 weeks when tested by immune electron microscopy. Using molecular biology techniques, shedding of viral particles has been observed close to 2 months after the ingestion. Immunoglobulin M (IgM) antibody to HEV parallels the rise of aminotransferase levels and declines in titer quickly, disappearing in a few weeks, although some patients may have detectable IgM anti-HEV for a few months. IgG anti-HEV level rises slowly and remains detectable for months, probably years after the infection.

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▪ Figure 28.1 Hematoxylin–eosin stain (×100) of a liver biopsy specimen from a 30-year-old Pakistani man with acute hepatitis E. Acinar transformation (gland-like) and cholestasis are observed along with necroinflammatory changes in the hepatic parenchyma.

P.741 Little is known about what happens once the virus is ingested; it is likely that the virus traverses through the small intestine and reaches the liver through the portal vein. The precise mechanism of hepatic uptake in humans is not known. Histopathologic features of HEV infection include necroinflammatory processes seen in all acute viral hepatitis and cholestatic hepatitis. HEV antigen was observed in the cytoplasm of infected hepatocytes as soon as 10 days after experimental intravenous inoculation and persisted for approximately 3

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weeks (17). Interestingly, in some outbreaks, the cholestatic hepatitis has been described as a gland-like transformation of hepatocytes with bile stasis (Fig. 28.1). The pathogenesis of HEV-associated hepatocyte injury is not completely defined.

Clinical Features The clinical features of HEV are difficult to differentiate from those of other types of viral hepatitis. The incubation period ranges between 15 and 60 days, usually becoming symptomatic 40 days after exposure. Adults appear to be at a greater risk of developing symptoms than adolescents and children. Most patients experience malaise, lack of appetite, nausea, and vomiting. A third of infected patients experience fever or abdominal pain. Few patients experience diarrhea, arthralgias, or skin rash. Serum tests show abnormal levels of aminotransferases and hyperbilirubinemia. Most patients do well, and because there are no chronic sequelae, they recover fully. However, fulminant hepatitis is associated with HEV more often than with any other viral hepatitis (18), particularly among pregnant women. Case fatality rates among HEV-infected pregnant women have been reported between 15% and 25% (19,20). However, work with experimental pregnant animals failed to show differences in severity of HEV infection when compared to nonpregnant animals (21).

Diagnosis Development of modern diagnostic tests was possible in part because of cloning of the virus (3) and the development of four recombinant viral antigens representing two distinct antigenic domains from two HEV strains (6). Before this advance, scientists relied on immune electron microscopy to detect viral particles in stool, with the consequent limitations of intensive labor and reduced sensitivity. Enzyme immunoassays are available to detect antibodies against HEV, and IgM or IgG classes of antibodies (6). These tests have an 80% to 100% probability of detecting the markers of acute infection (e.g., IgM anti-HEV). Data are limited to evaluate the longevity of IgG anti-HEV. Some studies have shown that IgG anti-HEV persists for at least 1 year after an acute infection (22); others have found that it may last longer. When 53 children from the outbreak in Mexico in the period 1986 to 1987 (11) were tested for anti-HEV 9 years later, 70% were found to have detectable IgG antibody (23).

Prevention and Treatment No defined antiviral therapy exists, and treatment for acute HEV is mainly supportive. In cases of fulminant HEV, liver transplantation

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should be considered. Some investigators have evaluated the efficacy of pre- or postexposure to Igs as prophylaxis to prevent acute HEV hepatitis. Unfortunately, even when using Igs from endemic regions (e.g., India) there was no clinical benefit observed (24). Prevention against HEV infection is associated with hygienic measures and clean water. No vaccine for human use is commercially available yet, but several recombinant HEV proteins have been evaluated as vaccine candidates. Table 28.2 shows some of these vaccines (25).

Table 28.2. Status of Hepatitis E Vaccines

Pharmaceutical company or

Clinical

research group

stage

Type 56-kDa ORF2

GlaxoSmithKline/United

Phase II,

protein VLPs

States Army/United States

III

(baculovirus)

National Institutes of Health

DNA vaccine

United States Navy

Preclinical

Live swine

United States National

Preclinical

virus vaccine

Institutes of Health

ORF, open reading frame; VLP, virus-like particles; DNA, deoxyribonucleic acid. Modified from World Health Organization. New vaccines against infectious diseases: research and development status, April 2005; http://www.who.int/vaccine .

P.742 GlaxoSmithKline (GSK) Biologicals has been working on the development of a hepatitis E vaccine to protect adolescents and adults. The vaccine is a 56-kDa recombinant product, expressed in insect cells from a baculovirus vector, initially developed at the National Institutes of Health (NIH), United States, and subjected to successful phase I studies (26). Recently, a blinded placebo-controlled study has been conducted in Nepal, involving 2,000 adults from the Royal Nepalese Army. The study is a collaboration between GSK, The United States Army, the Royal Nepalese Army, and the US NIH. The vaccine was administered as three injectable doses at 0, 1, and 6 months, and it was shown to be safe and immunogenic. The vaccine efficacy was

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calculated to be 97% among vaccine recipients because only three subjects among the 898 who were fully immunized developed acute HEV, while 66 of the 896 placebo recipients had acute HEV (Robert H. Purcell, personal communications 2006). The prospect of controlling hepatitis E is likely a reality in the near future.

Annotated References Balayan MS, Andjaparaidze AG, Savinskaya SS, et al. Evidence for a virus in non-A, non-B hepatitis transmitted via the fecal-oral route. Intervirology 1983;20:23–31. First scientific evidence of human-to-human infection and transmission of HEV to experimental animals. Dawson GJ, Chau KH, Cabal CM, et al. Solid phase enzyme linked immunosorbent assay for hepatitis E virus IgG and IgM utilizing recombinant antigens and synthetic peptides. J Virol Methods 1992;38:175–186. First description of enzyme-linked immunosorbent assay (ELISA) that enables the rapid serologic diagnosis of the antibody to HEV. Krawczynski K, Bradley DW. Enterically transmitted non-A, non-B hepatitis: identification of virus-associated antigen in experimentally infected cynomologous macaques. J Infect Dis 1989;159:1041–1049. Description of the creation of a new and solid animal model. Purcell RH, Nguyen H, Shapiro M, et al. Pre-clinical immunogenicity and efficacy trial of a recombinant hepatitis E vaccine. Vaccine 2003;21:2607–2615. Indicates the high probability of developing a vaccine to protect humans against HEV. Reyes GR, Purdy MA, Kim JP, et al. Isolation of a cDNA from the virus responsible for enterically transmitted non-A, non-B hepatitis. Science 1990;247:1335–1339. Experimental animal infectious bile was used to construct HEV recombinant libraries. The clone ET1.1 was characterized and found to represent a portion of the HEV genome.

References

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1. Choo QL, Kuo G, Weiner AJ, et al. isolation of a cDNA clone derived from a blood-borne non-A, non-B viral hepatitis. Science 1989;244:359.

2. Balayan MS, Andjaparaidze AG, Savinskaya SS, et al. Evidence for a virus in non-A, non-B hepatitis transmitted via the fecal-oral route. Intervirology 1983;20:23–31.

3. Reyes GR, Purdy MA, Kim JP, et al. Isolation of a cDNA from the virus responsible for enterically transmitted non-A, non-B hepatitis. Science 1990;247:1335–1339.

4. Wang L, Zhuang H. Hepatitis E: An overview and recent advances in vaccine research. World J Gastroenterol 2004;10:2157–2162.

5. Schlauder GG, Mushahwar IK. Genetic heterogeneity of hepatitis E virus. J Med Virol 2001;65:282–292.

6. Dawson GJ, Chau KH, Cabal CM, et al. Solid phase enzyme linked immunosorbent assay for hepatitis E virus IgG and IgM utilizing recombinant antigens and synthetic peptides. J Virol Methods 1992;38:175–186.

7. Viswanathan R, Sidhu AS. Infectious hepatitis: clinical findings. Indian J Med Res 1957;45(Suppl):49–58.

8. Wong DC, Purcell RH, Sreenivasam MA, et al. Epidemic and endemic hepatitis in India. Evidence for a non-A, non-B hepatitis. Lancet 1980;2:876–879.

9. Arankalle VA, Chadha MS, Tsarev SA, et al. Seroepidemiology of water-borne hepatitis in India and evidence for a third enterically transmitted hepatitis agent. Proc Natl Acad Sci 1994;91:3428– 3432.

10. Villarejos VM, Kirsten PH, Visona MS, et al. Evidence for viral hepatitis other than type A or type B among persons in Costa Rica. N Engl J Med 1975;293:1350–1352.

11. Velazquez O, Stetler HC, Avila C, et al. Epidemic transmission

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of enterically transmitted non-A, non-B hepatitis in Mexico, 19861987. JAMA 1990;263:3281–3285.

12. Morb Mor Wkly Rev Hepatitis E among US travelers 1989-92. 1993;42:1–4.

13. Meng XJ, Purcell RH, Halbur PG, et al. A novel virus in swine is closely related to the human hepatitis E virus. Proc Natl Acad Sci 1997;94:9860–9865.

14. Emerson SU, Purcell RH. Running like water—the omnipresence of hepatitis E. N Engl J Med 2004;351:2367–2368.

15. Vander Poel WHM, Verschoor F, Van der Heide R. Hepatitis E virus sequences in swine related to sequences in humans, the Netherlands. Emerg Infect Dis 2001;7:970–976.

16. Chauhan A, Jameel S, Dilaware JB, et al. Hepatitis E virus transmission to a volunteer. Lancet 1993;341:149–150.

17. Krawczynski K, Bradley DW. Enterically transmitted non-A, non-B hepatitis: identification of virus-associated antigen in experimentally infected cynomologous macaques. J Infect Dis 1989;159:1041–1049.

18. Nanda SK, Yalenkaya K, Panigrahi AK, et al. Etiological role of hepatitis E virus in sporadic fulminant hepatitis. J med Virol 1994;42:133–137.

19. Khuroo MS, Teli MR, Skidmore S, et al. Incidence and severity of viral hepatitis in pregnancy. Am J Med 1981;70:252–255.

20. Tsega E, Hanson BG, Krawczynski K, et al. Acute sporadic viral hepatitis in Ethiopia: causes, risk factors, and effect on pregnancy. Clin Infect Dis 1992;14:961–965. P.743 21. Tsarev SA, Tsareva TS, Emerson SU, et al. Experimental hepatitis E in pregnant rhesus monkeys: failure to transmit hepatitis E to offspring and evidence of naturally acquired antibodies to HEV. J Infect Dis 1995;172:31–37.

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22. Koshy A, Grover S, Hyams KC. Short term IgM and IgG antibody responses to hepatitis E infection. Scand J Infect Dis 1996;28:439–441.

23. Sjogren MH, Siegl G. Advances in Hepatitis A and Hepatitis E. In: Rizzetto M, Purcell RH, Gerin JL, et al., eds. Viral hepatitis and liver diseases, Turin, Italy: Minerva Medica. 1997:903–905.

24. Khuroo MS, Dar MY. Hepatitis E: evidence for person-to-person transmission and inability of low dose immune serum globulin from an Indian source to prevent it. Indian J Gastroenterol 1992;11:113–116.

25. World Health Organization. New vaccines against infectious diseases: research and development status, April 2005; http://www.who.int/vaccine.

26. Purcell RH, Nguyen H, Shapiro M, et al. Pre-clinical immunogenicity and efficacy trial of a recombinant hepatitis E vaccine. Vaccine 2003;21:2607–2615.

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Copyright ©2007 Lippincott Williams & Wilkins > Table of Contents > Volume I > Section V - Viral Hepatitis > Chapter 29 - Hepatitis B and D

Chapter 29 Hepatitis B and D Anna S.F. Lok Hari S. Conjeevaram Francesco Negro

Key Concepts z

There are approximately 400 million hepatitis B carriers worldwide and 1.25 million carriers in the United States. The prevalence of hepatitis B virus (HBV) infection is related to the predominant mode of transmission and the age at infection.

z

Acute HBV infection may manifest as subclinical hepatitis, icteric hepatitis, or fulminant hepatitis. Chronic HBV infection may manifest as inactive carrier state, chronic hepatitis, cirrhosis, or hepatocellular carcinoma (HCC).

z z

Many lines of evidence support an etiologic association between chronic HBV infection and HCC. The aims of antiviral treatment of chronic hepatitis B are to suppress HBV replication, induce remission in liver disease, and prevent the development of cirrhosis and (HCC).

z

Approved treatments of chronic hepatitis B include interferon-α (standard and pegylated), lamivudine,

z

Hepatitis D virus is dependent on HBV. Hepatitis D occurs as coinfection with HBV or superinfection in

adefovir, and entecavir. persons with chronic HBV infection.

Epidemiology Hepatitis B infection is a global public health problem. It is estimated there are approximately 400 million hepatitis B virus (HBV) carriers in the world, of whom over 500,000 die annually from hepatitis B– associated liver disease (1). In the United States, an estimated 1.25 million individuals are chronically infected with HBV (2,3). Hepatitis B carrier rate varies from 0.1% to 20% in different areas of the world (Table 29.1). The wide range in carrier rate is related to differences in the predominant mode of transmission and the age at infection. Understanding the epidemiology of hepatitis B is important in the implementation of vaccination programs for the prevention of HBV infection.

Prevalence The prevalence of HBV infection varies in different geographical areas (Table 29.1) (4). In low prevalence areas such as the United States, western Europe, Australia and New Zealand, the hepatitis B surface antigen (HBsAg) carrier rate is approximately 0.1% to 2%. In intermediate prevalence areas like the Mediterranean countries, Japan, India and Singapore, the carrier rate is approximately 3% to 5%. In high prevalence areas such as Southeast Asia and sub-Saharan Africa, the carrier rate is 10% to 20%. The prevalence of current and past HBV infection is estimated to be 5% in the United States and close to 100% among adults in some parts of Southeast Asia and Africa. In general, there is an increasing prevalence of HBV infection with age. Within the United States, the prevalence of HBV infection is higher among African Americans, Hispanics and Asians than in the white population (3). Several communities have been reported to have higher carrier rates than their neighboring regions, namely, Alaskan Eskimos, Asian-Pacific Islanders and Australian Aborigines. In most high prevalence areas such as Hong Kong and China, perinatal transmission is the major mode P.746 of spread accounting for 40% to 50% of chronic HBV infection (5,6). However, horizontal spread during the first 2 years of life is the major mode of transmission in other endemic areas including Africa and the Middle East (7,8). The exact reason for the preponderance of perinatal transmission among Orientals is not clear but is at least in part related to the high prevalence of hepatitis B e antigen (HBeAg) among Asian carriers of reproductive age—40% to 50% versus 10% to 20% among African carriers of the same agegroup (6,9). In intermediate prevalence areas, transmission occurs among all age-groups but early childhood infection accounts for most cases of chronic infection. In low prevalence areas, most infections are acquired in early adult life through unprotected sexual intercourse or intravenous drug abuse. The age at infection has a significant impact on the clinical outcome because chronic infection occurs in

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approximately 90% of infants infected at birth, in 25% to 50% of children infected between the age of 1 and 5 years, and in less than 5% of those infected during adult life (5,10,11,12).

Table 29.1. Patterns of Hepatitis B Virus Infection

Prevalence

High

Intermediate

Low

Carrier rate

8%–20%

3%–7%

0.1%–2%

Geographical

Southeast Asia

Mediterranean basin

United States and

distribution

China

Eastern Europe

Canada

Pacific Islands

Central Asia

Western Europe

Sub-Saharan Africa

Japan

Australia

Alaska (Eskimos)

Latin and South

New Zealand

America Middle East

Predominant age at

Perinatal and early

infection

childhood

Predominant mode of

transmission

Early childhood

Adult

Maternal–infant

Percutaneous

Sexual

Percutaneous

Sexual

Percutaneous

Mode of Transmission Transfusion In the 1960s, the risk of hepatitis B infection from transfusions of commercial blood was as high as 50% and HBsAg was detected in up to 60% of patients with post-transfusion hepatitis. The exclusion of paid donors and the application of hepatitis B serologic screening in the 1970s dramatically reduced the incidence of post-transfusion HBV infection (13). Currently, approximately 80 cases of transfusionassociated HBV infection are reported in the United States each year (14). In the United States, both HBsAg and hepatitis B core antibody (anti-HBc) are used for blood donor screening. Anti-HBc was initially used as a surrogate marker for non–A non–B hepatitis virus. Anti-HBc has been retained after the implementation of hepatitis C testing to detect donors who are in the window phase during recovery from acute hepatitis B or who have low level chronic HBV infection. The practical value of anti-HBc screening is not clear because of the possibility of false-positive test result, the low incidence of transfusion-associated HBV infection with HBsAg screening only in low prevalence areas, and the need to exclude as many as 22% of the donor population in high prevalence areas (15,16,17,18). Currently, the risk of transfusion related hepatitis B from blood donors who test negative for HBsAg and anti-HBc is estimated to be 1 in 63,000 (range 1:30,000 to 1:250,000 episodes per unit transfused) (19). Recently there have been debates on serology versus nucleic acid testing (NAT) of blood donors. A recent review concluded that NAT for HBV will probably detect only a few more donor units that may be associated with risk of transmitting HBV infection compared to serologic screening for HBsAg and anti-HBc (20). With the current estimated 13 million donations per year in the United States and 1.8 transfused components per donation, introduction of NAT would be expected to prevent 30 to 35 HBV-containing transfusions per year. Because of the low rates of viral persistence and clinical disease following HBV transmission in the setting of seronegative blood transfusion, the clinical impact and cost-effectiveness of NAT is expected to be low. NAT of whole blood was estimated to avert 9 to 37 HBV infections at an additional cost of US $39 to 130 million per year (21).

Percutaneous transmission Percutaneous inoculation of blood or body fluid plays a major role in the transmission of hepatitis B infection. Needle sharing by intravenous drug users is an important route of transmission of hepatitis B. Reuse of contaminated needles for tattoos, acupuncture and ear piercing also provide opportunities for percutaneous transmission.

Sexual transmission In the United States and many developed countries, sexual transmission is the most important mode of spread

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P.747 of HBV. The Centers for Disease Control and Prevention reported that sexual transmission accounts for almost 50% of acute HBV infection among individuals in whom data on risk factors were available (22). A high prevalence of chronic HBV infection has been reported in men who have sex with men as well as in heterosexuals with multiple sex partners. The annual incidence of new HBV infections among homosexual men decreased significantly in the 1980s as a result of education on safe sex practice to prevent human immunodeficiency virus (HIV) infection (23). However, recent reports in the United States suggest that both heterosexual transmission and transmission among homosexual men are on the rise (22). The risk of sexual transmission of HBV infection is proportional to the number of lifetime sex partners, low education level, paid sex, and history of sexually transmitted diseases.

Perinatal transmission The rate of neonatal HBV infection from an infected mother is less than 10% in Western countries. Nonetheless, an estimated 20,000 infants are born to HBsAg carrier women in the United States annually (24). In areas with high endemicity such as China, perinatal infection is the most common mode of transmission. The risk of maternal–infant transmission is related to the HBV replicative status of the mother. The risk is 85% to 90% for infants born to HBeAg-positive mothers and 30% for infants born to HBeAg-negative mothers (25). More recent studies demonstrated that maternal serum HBV DNA levels correlate better with the risk of transmission (26). Maternal–infant transmission takes place at the time of delivery by maternal–fetal transfusion or exposure to maternal blood during passage through the birth canal and postnatally through intimate mother–baby contact. Intrauterine transmission is uncommon as HBsAg is detected in infants much later. In addition, passive–active immunization at birth has been demonstrated to have an efficacy rate of more than 90% in the prevention of HBV infection (27). Cesarean section has not been shown to eliminate the risk of perinatally acquired HBV infection (28) and should not be routinely recommended for carrier mothers. Although HBsAg can be detected in breast milk, there is no evidence that HBV infection can be transmitted by breast-feeding (29); infants born to carrier mothers may be breast-fed if they have been vaccinated. The risk of transmission during amniocentesis is also low (30). Universal vaccination of all newborns and additional administration of hepatitis B immune globulin (HBIG) to those who are born to carrier mothers were initiated in many Southeast Asian countries in the 1980s. These programs have led to significant reduction in HBsAg carrier rate as well as decrease in the incidence of hepatocellular carcinoma (HCC) among children (31).

Health care environment HBV is the most commonly transmitted blood-borne virus in the health care setting (32). Transmission generally occurs from patient to patient or from patient to health care personnel via contaminated instruments or accidental needle stick injury. The risk of acquiring HBV infection after needle stick injury is related to the HBeAg status of the source patient. There have been several outbreaks of hepatitis B infection in the health care environment. One report involved transmission from a patient with diabetes to another through the contaminated platform of a spring-loaded lancet device for finger sticks (33). Outbreaks of HBV infection were also reported in several hemodialysis units as a result of failure to identify and isolate patients who were infected and to vaccinate those who were susceptible (34). Transmission of HBV infection from health care workers to patients is rare. One outbreak was traced to a cardiothoracic surgeon despite no identified flaws in precautions on infection control during operations (35). Transmission was thought to be related to tears in the gloves and minor cuts on the surgeon's fingers during prolonged suturing. Nosocomial transmission can be prevented by screening of blood and blood products, use of disposable needles and equipment, proper sterilization of surgical instruments, enforcement of infection control measures, and vaccination of health care workers. In many developed countries, guidelines have been established to define the parameters within which health care workers with hepatitis B can operate. In the United States, health care workers who are HBeAg positive are restricted from performing invasive procedures (36,37). The Centers for Disease Control and Prevention recommends that health care workers with HBV infection should not perform exposure prone procedures unless they have sought counsel from an expert review panel and have been advised on the circumstances under which they may perform such procedures. The difference in the scope of permissible work between HBeAg-positive and HBeAg-negative carriers is related to the traditional concept that HBeAg is a reliable marker of infectivity. However, a recent report found that transmission of HBV infection occurred from four HBeAg-negative surgeons. These surgeons had detectable HBV DNA in serum and were infected with precore stop codon variants (38). This and other similar incidents have led to the proposal that serum HBV DNA levels be used to categorize the infectivity of health care workers but it is also known that serum HBV DNA levels can fluctuate and may be intermittently undetectable in patients with chronic HBV infection (37,39,40). As vertical transmission is rarely documented with maternal HBV DNA levels below 10 7 copies/mL, it is thought that transmission of HBV P.748 via needle-stick injury is also unlikely to occur at HBV DNA levels below 10 7 copies/mL (39). It has been proposed that health care workers with higher HBV DNA levels receive antiviral therapy to enable them to return to work without risking nosocomial infection.

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Hemodialysis patients Patients with renal failure on hemodialysis may be infected through blood transfusions, contamination of dialysis machines or equipment, as well as interpersonal horizontal transmission in the dialysis units. Improved infection control and the availability of vaccines have reduced the incidence of HBV infection among hemodialysis patients from 3% in 1980 to 0.1% in 1993 in the United States and has remained stable in the past decade (34,41). However, dialysis patients have impaired antibody response to vaccines. Therefore, vigilance is still needed to prevent outbreaks. In a recent survey of all US chronic hemodialysis centers (41) the percent of patients vaccinated against HBV infection increased from 47% to 56% and the percent of staff vaccinated increased from 87% to 90% between 1997 and 2002. Although the overall incidence of HBV infection did not correlate with the infection control practices, it was noted that the incidence of HBV infection in 2002 was higher among patients in centers where injectable medications were prepared on a medication cart compared to a dedicated medication room. A possible contributing factor for continued transmission of HBV infection in adult hemodialysis units appears to be the presence of occult HBV infection (serum HBsAg negative but HBV DNA positive). In a recent study of 241 adult hemodialysis patients in a North American urban center (42), only two patients (0.8%) were HBsAg-positive but nine (4%) HBsAg-negative patients were HBV DNA positive.

Transplantation Currently, organ donors are routinely screened for HBsAg. Transmission of HBV infection has been reported after transplantation of extrahepatic organs such as kidneys from HBsAg-positive donors. This may be related to residual blood in the vascular pedicles due to inadequate flushing or the presence of infectious virions in the kidneys. Transmission of HBV infection has also been reported after transplantation of avascular tissues such as cornea (43). The role of anti-HBc testing in organ donor screening is uncertain because of the possibility of falsepositive results, the potential loss of up to 5% of donors even in low endemic areas (44), and the uncertainty about the infectivity of organs from donors who have isolated anti-HBc (45). The incidence of HBV infection from donors with isolated anti-HBc is very low (0% to 2%) in heart and kidney recipients but varies from 0% to 78% in liver recipients (44,46,47,48). A recent study found that the estimated probability of undetected hepatitis B viremia is higher among tissue donors compared to first-time blood donors and the addition of NAT to the screening of tissue donors is expected to reduce the risk of HBV infection (49).

Others In endemic areas, horizontal transmission among children may result from close bodily contact leading to transfer of virus across minor skin breaks and mucous membranes. Blood-feeding insects like mosquitoes have been demonstrated to serve as vectors for HBV transmission in animal models but firm evidence for this mode of transmission in humans is lacking. Various body secretions have been reported to test positive for HBsAg but only semen and saliva have been consistently shown to harbor infectious virions (50,51). Although HBV DNA has been detected in the saliva of some hepatitis B carriers, there is no convincing evidence that hepatitis B can be transmitted orally (52,53). As HBV survives for a long time outside the human body, transmission via contaminated environmental surfaces and daily articles such as toothbrushes, razors, eating utensils or even toys may also be possible.

High-Risk Groups Health care workers have a higher hepatitis B carrier rate than the general population. The prevalence is particularly high among surgeons, pathologists, and physicians working in hemodialysis and oncology units. Apparent skin breaks, minor cuts and accidental needle stick injuries serve as portals of entry. Other health care workers having increased risk of HBV infection include dentists and laboratory personnel who have contact with serum. Institutionalized mentally handicapped persons as well as their attendants and family members also have a high rate of hepatitis B infection. Despite screening of blood products, patients requiring frequent transfusion of blood or blood products—those with thalassemia and hemophilia—have an increased risk of contracting hepatitis B infection. Other high-risk groups include intravenous drug users particularly those who share syringes, men who have sex with men and promiscuous heterosexuals, immigrants from HBV endemic countries, and spouses, sexual partners, and household members of HBV carriers.

Changing Epidemiology The worldwide incidence of HBV infection is decreasing (1,22). Mass vaccination for newborns and catch-up vaccination for children and adolescents play a major role in reducing HBV infection among infants and P.749 children. Increased public awareness of hepatitis, educational campaigns to prevent HIV infection leading to modification of high risk sexual behavior, and reduction of syringe sharing among intravenous drug

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users have contributed to the decrease in HBV infection among adults. In the United States, the incidence of acute hepatitis B has significantly declined over the past decade. According to the Centers for Disease Control and Prevention, the incidence of acute hepatitis B during the years 1990 to 2002 has declined from 8.5 per 100,000 population to 2.8 per 100,000 population (22); the most significant decline was seen among ages 0 to 19 years (rate of 3.0 to 0.3). The decline was more marked in women compared to men. However, incidence has remained the same if not increased among certain adult groups: Those with multiple sexual partners, men who have sex with men, and injection drug users. Sexual transmission among susceptible individuals remains a significant risk factor for hepatitis B transmission in the United States. This is in part related to lack of resources and infrastructure for vaccination of adults as well as missed opportunities. In a recent study of 833 men who have sex with men, aged 15 to 29 years, 44% were susceptible to HBV infection; most of these men were found to be either unaware of protective vaccines, had never been offered vaccination, or perceived themselves at low risk (54). Another important aspect of HBV epidemiology is that in many developed countries, immigrants from countries that are endemic for HBV infection now constitute an increasing proportion of those with chronic HBV infection (55). In addition, some studies also showed that these immigrants have a higher incidence of acute HBV infection (56). These and other studies (57) suggest that screening and immunization of susceptible adults along with immunization of children (especially if they were born in countries where universal vaccination is not in place) whose parents immigrated from HBV endemic countries may be of great importance in controlling HBV infection in developed countries.

Vaccination Indications Vaccination against hepatitis B remains the mainstay of prevention. Universal vaccination of all newborn or at least newborn of all HBV-infected mothers is currently practiced in most countries throughout the world. The World Health Organization (WHO) has recommended that combination of hepatitis B and childhood vaccines be used where possible, to reduce the logistic costs of vaccine delivery especially in areas where it is most needed. However, due to decreased immunogenic potential of other vaccines especially during the initial 6 weeks after birth, it is currently recommended that only monovalent vaccines should be administered to the newborn. In some developed countries, where universal vaccination of all newborn is not in place, vaccination of adolescents to prevent sexual transmission is implemented. Vaccination of adults is recommended for high risk groups including health care workers, men who have sex with men, persons with multiple sex partners, injection drug users, sex partners, and household members of HBV carriers, public safety workers, institutionalized patients, and patients on chronic hemodialysis (Table 29.2) (58).

Table 29.2. Indications for Hepatitis B Vaccine

1. All newborns a 2. All children and adolescents not vaccinated at birth 3. High-risk adults: a. Health care workers b. Men who have sex with men c. Persons with multiple sexual partners d. Injection drug users e. Patients on hemodialysis f. Institutionalized patients g. Health care workers and public safety workers h. Spouse, sexual partners and household members of HBV carriers

a

For infants born to carrier mothers, hepatitis B immune globulin (HBIG) is also administered at

birth.

Administration Schedule There are two types of hepatitis B vaccines, plasma-derived and recombinant, the latter is currently used in most countries. Recombinant HBV vaccines consist of HBV small S protein (HBsAg) produced by yeast or mammalian cells. Hepatitis B vaccine is usually administered intramuscularly in three doses at 0, 1 and 6 months, the dose being 10 to 20 µg in adults and 5 to 10 µg in children (Table 29.3). For adults, the injections are given in the deltoid muscle, whereas in newborns and young children the recommended site is the anterolateral thigh. In patients with hemophilia, P.750

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it is recommended to administer the vaccine subcutaneously.

Table 29.3. Hepatitis B Vaccines and Dosage Recommendations

Vaccine brand Engerix-B

Recombivax HB

(Optional two doses)

Age-group (y)

Dose (µg)

Volume (mL)

Number of doses

0–19

10

0.5

3

≥20

20

1.0

3

0–19

5

0.5

3

≥20

10

1.0

3

11–15

10

1.0

2

For hemodialysis patients, recommended dose is 40 µg with each dose (Engerix-B 40 µg/2.0 mL and Recombivax HB dialysis formulation 40 µg/1.0 mL).

For infants born to HBsAg-negative mothers and unvaccinated children/adolescents up to 19 years of age, 3 doses (0, 1 and 6 months) of vaccine at half strength should be administered. For adults 20 years and older, the same regimen is implemented using full dose (10 µg of Recombivax HB and 20 µg of Engerix-B). An alternative two-dose schedule had been approved for adolescents. For newborns of HBsAg carrier mothers, HBIG 0.5 mL and the first dose of vaccine should be administered at birth, using different sites. Combination of HBIG and hepatitis B vaccine has been shown to be 95% efficacious in preventing perinatal transmission of HBV infection (27,59,60). For patients on hemodialysis or immunocompromised patients, higher doses of vaccine are needed: 40 µg of Recombivax HB or Engerix-B. Anti-HBs titer should be monitored annually, and booster doses administered when hepatitis B surface antibody (anti-HBs) titer falls below 10 IU/L. Follow-up testing for protective antibodies is recommended for individuals who continue to be at risk including infants born to HBsAg-positive mothers, health care workers, hemodialysis patients, and sexual partners of HBsAg carriers (58). Some vaccines have also incorporated pre-S1 (large S) and/or pre-S2 (middle S) proteins to increase the immunogenicity but these vaccines are not available in most countries.

Efficacy A protective response defined as an anti-HBs titer more than 10 IU/L is achieved in approximately 95% of vaccine recipients. Several studies have shown that vaccination is effective in inducing protective immunity and in preventing HBV infection even in men who have sex with men, (61,62,63) and newborns of carrier mothers (27,59,64). In countries where the prevalence of HBeAg among carrier mothers is low, it has been shown that the vaccine alone has similar efficacy in preventing HBV infection as a combination of vaccine and HBIG in preventing perinatal infection (64). Although this approach can be cost saving, it may not be adequate in countries where the prevalence of HBeAg among carrier mothers is high or in countries where a high percent of HBeAg-negative mothers have high serum HBV DNA levels.

Factors Associated with Nonresponse and Management of Vaccine Nonresponders Approximately 2.5% to 10% of vaccine recipients fail to respond with adequate anti-HBs titers after one course of HBV vaccine. The reasons for nonresponse are several and include older age, obesity, chronic medical illnesses such as renal failure, diabetes, cirrhosis, immunosuppression such as patients with HIV infection or organ transplantation, and technical problems such as intragluteal injection and inadvertent freezing of the vaccines. Nonresponse to HBV vaccine has been reported to be associated with impaired lymphocyte activation as well as genetic factors including certain human leukocyte antigen (HLA) class II genes such as HLADRB1*0301 and cytokine gene polymorphisms (65,66,67). For individuals who failed to respond after a full course of vaccination the recommendation is to repeat another course of vaccine. If a person still remains a nonresponder, further vaccination is usually not effective but most of these individuals can mount an adequate immune response upon infection because

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exposure to HBV stimulates both T and B cell responses to HBsAg as well as hepatitis B core antigen (HBcAg). Nonresponders to two courses of vaccine should be tested for HBsAg as some may be undiagnosed carriers.

Durability of Vaccine Response and Need for Boosters Several studies showed that 30% to 66% of individuals had protective levels of anti-HBs (≥10 mIU/mL) for even 15 years or more after receiving plasma derived HBV vaccines and 90% had anamnestic response after booster vaccination (68,69,70,71). Breakthrough infections appear to occur mostly among those who did not have an initial response to vaccination (70). Two recent studies found that persistence of anti-HBs response up to 18 years after administering plasma-derived and recombinant vaccines was comparable (68,72). Although anti-HBs titers decline with time, the incidence of HBV infection among individuals who were vaccinated at birth is low and there is no consensus on the need for booster vaccination. The European Consensus Group on hepatitis B Immunity in 2000 recommended that booster doses be considered in those who are immunocompromised or at a high risk of exposure (73). A recent report of the Steering Committee for the prevention and control of infectious diseases in Asia (74) recommended booster vaccination approximately 10 to 15 years after primary vaccination especially among children vaccinated as infants; when monitoring of antibody levels is not feasible; in all immunocompromised patients with anti-HBs levels below 10 mIU/L; and for health care workers in endemic countries. By contrast, a Viral Hepatitis Prevention Board that convened in 2004 concluded that existing data do not support the need for booster doses in universal HBV immunization programs, but the risk of P.751 infection through sexual or occupational exposure later in life on those vaccinated as neonates is unknown (75).

Impact of Hepatitis B Virus Vaccination HBV vaccination has been shown to reduce the incidence of acute HBV infection and HCC, and the prevalence of chronic HBV infection (31,57,76,77). HBV vaccine is the first vaccine that has been shown to prevent cancer (HCC) in humans. After the implementation of a nationwide vaccination program for newborn and children in 1984, the carrier rate among children decreased from 10% in 1984 to less than 1% in 1999 (31) while the incidence of HCC declined from 0.79 cases per 100,000 between the years 1981 and 1986 to 0.36 cases between the years 1990 and 1994 (77). In the United States, universal vaccination of all newborns was implemented in 1991 and it was expanded to include vaccination of all adolescents aged 11 to 12 years in 1995, and children aged less than 18 years, who had not been vaccinated previously, in 1999. This has resulted in a significant 89% reduction of acute hepatitis B in children and adolescents during 1990 to 2002 (22).

Safety of Hepatitis B Vaccination The safety of hepatitis B vaccination has been well established. The most common adverse reaction is soreness over the injection site. Other adverse reactions include low-grade fever, malaise, headache, arthralgia and myalgia. Hepatitis B vaccines have no teratogenic effects and can be administered during pregnancy (78,79). There has been concern about the possibility of hepatitis B vaccine leading to the development of demyelinating central nervous system diseases including multiple sclerosis (80,81) and also Guillain-Barre syndrome (82). It has been speculated that these “adverse reactions” could be related to “molecular mimicry.” However, many studies have failed to show a statistically significant temporal or causal association between HBV vaccine and these neurologic or immunologic conditions (83,84,85,86,87). Because of concerns about mercury exposures, current preparations of HBV vaccines do not contain thimerosal as a preservative. Based upon current evidence and the proven benefit of hepatitis B vaccine, the WHO has recommended that all countries continue their hepatitis B vaccine programs (88).

Special Settings Isolated antihepatitis B core individuals The presence of an isolated anti-HBc does not always denote prior exposure to HBV infection. HBV vaccination has been recommended to differentiate those who had prior exposure from those with falsepositive anti-HBc test results (15). With improved specificity of current anti-HBc assays, most individuals with isolated anti-HBc have genuinely positive test results and do not need to be vaccinated but there is no harm if vaccine is administered.

Patients on chronic hemodialysis Response to HBV vaccine is impaired in patients with renal failure. A recent report from the Cochrane group found that there was no difference in response between plasma derived and recombinant HBV

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vaccines (89). Response to HBV vaccine was similar in hemodialysis versus peritoneal dialysis patients (90).

Patients with chronic liver disease Hepatitis B vaccination along with vaccination against hepatitis A is currently recommended for all patients with underlying chronic liver disease. Acute hepatitis B superimposed on chronic hepatitis C has been reported to be associated with increased risk of liver failure (91). Immune response to HBV vaccines among patients with chronic liver disease varies from 70% to 90% (91). In general, response rates are similar to healthy subjects with no liver disease except in patients with cirrhosis but response rates are substantially lower (6 m 2. HBeAg–, anti-HBe+ 3. Serum HBV DNA Table of Contents > Volume I > Section V - Viral Hepatitis > Chapter 30 - Hepatitis C

Chapter 30 Hepatitis C Gary L. Davis

Key Concepts z

Hepatitis C virus (HCV) is a single-stranded ribonucleic acid (RNA) virus that replicates at a rapid rate but lacks proofreading ability. As a consequence, it has a high degree of genetic diversity that has led to evolution into several distinct viral genotypes. This genetic diversity affects the biology of the virus, in particular its susceptibility to interferon-based therapy. It may also be an important factor, along with signaling interference and effector modulation, in allowing the virus to evade elimination by the host immune response.

z

The serologic test (anti-HCV) is sensitive for diagnosing HCV infection. Molecular tests that measure HCV RNA levels are extremely sensitive and are helpful in confirming infection and managing treatment.

z

The incidence of acute HCV infection has fallen dramatically in the United States. The major risk factor for infection remains intravenous drug use.

z

Chronic infection develops in 50% to 90% of acutely infected persons; it occurs less commonly in the young. Despite the declining incidence of HCV, the prevalence remains high (3 to 4 million persons) because of this high chronicity rate.

z

Both acute and chronic HCV infections are usually asymptomatic. Chronic hepatitis C is a slowly progressive disease but results in significant disease morbidity in only a minority of infected persons. However, because HCV infection is so highly prevalent, chronic hepatitis C is among the most common causes of chronic liver disease in the United States and the leading indication for liver transplantation.

z

There is no effective pre- or postexposure prophylaxis for HCV infection. Interferon-based regimens are the only effective treatment for patients with acute or chronic hepatitis, although many patients with acute infection recover spontaneously. Sustained loss of virus is now achievable in more than 50% of patients with chronic hepatitis C who are treated with the combination of long-acting (pegylated) interferons and ribavirin. Patients who have a sustained virologic response to treatment also have significant and persistent histologic improvement.

History Although our awareness and understanding of viral hepatitis has risen dramatically over the last 4 decades, this is not a new problem. Descriptions of jaundice exist in the literature as far back as several centuries BC and are referenced in the Babylonian Talmud and the writings of Hippocrates (1). The infectious nature of the disease was first recognized in the 8th century BC P.808 by Pope Zacharias (2). However, most of the reports of large population epidemics over the last several centuries were probably due to enteral transmission of what is now known as hepatitis A. It was not until the introduction of the practice of inoculation for smallpox vaccination in the 1880s that the percutaneous route of transmission of the disease was recognized (3). Numerous reports of jaundice occurring in patients receiving vaccines or injections for diabetes or syphilis followed during the early 20th century (4,5,6). The first association of blood transfusion with the development of hepatitis was reported in 1943 (7). The landmark studies of Krugman et al. at the Willowbrook State School in New York documented the transmissibility of hepatitis by human plasma (8) and confirmed the long-standing clinical observations that both parenteral (“serum hepatitis”) and enteric (“infectious hepatitis”) transmission could occur (9). Frustrating and largely unsuccessful efforts to identify the specific agents responsible for hepatitis continued over several decades (10). A serologic marker for hepatitis B was first identified by Blumberg in 1965 (11), although its association with the parenterally transmitted entity then known as serum hepatitis was not recognized until 2 years later (12). The recognition of the specific viral agents responsible for hepatitis B and A was made over the next few years (13,14). These discoveries were obviously major breakthroughs, but it quickly became apparent that most cases of hepatitis could not be explained by either the hepatitis A virus or the hepatitis B virus (HBV).

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The entity of non-A, non-B hepatitis was formally christened by Prince in 1974 (15). An infectious agent was suspected on the basis of the observations that it was parenterally transmissible to chimpanzees and humans by blood transfusion (16). A series of experiments by Bradley et al. at the Centers for Disease Control and Prevention (CDC) characterized the nature of the infectious agent (17,18). Filtration studies suggested that the agent was between 30 and 50 nm in size. Its infectivity was abolished by chloroform, suggesting the presence of a lipid envelope (17), as well as by formalin, heat (100°C for 5 minutes or 60°C for 10 hours), and β-propiolactone ultraviolet light (18). However, the conventional virologic and immunologic techniques of the time failed to isolate the responsible agent. Scientists at Chiron Corporation, Emeryville, CA, and in Japan used a different tactic based on recently described molecular biologic techniques (19,20). This was based on Bradley's work, which suggested that the non-A, non-B agent was a virus. However, because the genomic nature of this putative virus was not known (although a flavi-like ribonucleic acid [RNA] viral agent was suspected), both deoxyribonucleic acid (DNA) and RNA were extracted for cloning from a large volume of infected serum (19). After extensive ultracentrifugation, which was sufficient to pellet down the smallest of known infectious agents, total nucleic acid was extracted and both RNA and DNA were converted to complementary DNA (cDNA). Restriction fragments were cloned into a recombinant bacteriophage vector to form a cDNA library. These phages were then inserted in Escherichia coli capable of transcribing and expressing the encoded peptide, and the resulting products were screened against sera from patients with non-A, non-B hepatitis under the assumption that sera from infected patients should contain antibody against the agent. After more than 1 million clones were screened, 5 clones were found to be reactive. Of these, one clone (5-1-1) was shown to bind not only antibodies present in the serum of patients with non-A, non-B hepatitis but also those in experimentally infected chimpanzees who appeared to seroconvert several weeks after exposure (21). Identification of other clones with overlapping regions of the viral complimentary DNA allowed these investigators to establish the entire viral genome. This breakthrough led to an explosion of research on this viral agent, now designated as hepatitis C virus (HCV), and its disease, now called hepatitis C. With the development of antibody-based detection systems (see later), HCV was found to be the major cause of non-A, non-B hepatitis (22,23,24). An estimated 170 million persons worldwide are infected by HCV, and it is perhaps the most common cause of chronic liver disease in the United States.

Virology HCV is the only member of the Hepacivirus genus of the Flaviviridae family. The viral genome is contained within a nucleocapsid that is encased in an envelope derived from host membranes into which viral-encoded glycoproteins are inserted (25). Spherical 50-nm viral particles have been identified by electron microscopy (26,27). Two populations of virus appear to exist in serum on the basis of densitygradient analysis (26). The high-density fraction is thought to represent free or immunoglobulin-bound virus, whereas a lower-density fraction appears to be bound to low-density lipoproteins (LDL) (28,29). The pathogenic significance of the latter is discussed later.

Genomic Organization, Viral Proteins, and Replication HCV contains a 9.6-kb positive-sense, single-stranded RNA genome that consists of a highly conserved 341-base 5′ noncoding region, a single long open reading frame (ORF) of 9,033 to 9,099 bases, and a 3′ noncoding region. The ORF encodes a polyprotein precursor of approximately 3,000 amino acids (25). This polyprotein is cleaved co- and post-translationally by both P.809 cellular and viral proteases to produce at least ten polypeptides with various functions in replication and virus assembly (30,31) (Fig. 30.1). On the basis of phylogenetic tree analysis, genetic organization, and hydrophobicity patterns, HCV is related to flaviviruses and pestiviruses and distantly to plant viruses (32). However, HCV has sufficient diversity to justify classification into a separate genus and therefore it has been assigned as the single member of the Hepacivirus genus of the family Flaviviridae (33). The nomenclature of the respective viral proteins is also in accordance with that of the Flaviviridae family (34). Given the factors that influence viral diversity, it is difficult to estimate the age of the HCV by phylogenetic analysis. Nonetheless, ancestors of the oldest genotypes of HCV probably originated in western and sub-Saharan Africa (genotypes 1, 2, and 4) and Southeast Asia (genotypes 3 and 6) (33). Some genotypes and common subtypes evolved later. For example, the subtypes of genotype 2 probably evolved within the last 90 to 150 years. Subtypes 1b likely evolved 60 to 70 years ago, and its global distribution suggests that it disseminated over a short period (33). The recent evolution of genotype 3a (about 40 years) and its high prevalence among intravenous drug users suggest that it may have evolved and spread through the practice of needle sharing in the 1960s (33).

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▪ Figure 30.1 Hepatitis C virus (HCV) genome and encoded polyprotein showing regions and functions. C, core; E, envelope; NS, nonstructural; IRES, internal ribosomal entry site; UTR, untranslated region; RNA, ribonucleic acid; pU, poly-uradine.

Virus Replication Identification of HCV in the cytoplasm of hepatocytes by immunohistochemistry and in situ hybridization suggests that the liver is the site of viral replication (35,36). This is further supported by the detection of negative-strand HCV RNA, the replication template, in hepatocytes. Although there is some evidence to support extrahepatic reservoirs of virus, including lymphocytes, gut epithelial cells, and the central nervous system, it remains unclear whether these sites simply harbor virus or are actually sites of replication (37,38,39). Our early understanding of the replication of the HCV was based on the assumption that it must resemble the replication of genetically related flaviviruses. An important breakthrough was the creation of functional subgenomic replicons by Lohmann et al. in 1999 (40). These replicons consisted of subgenomic (incomplete) HCV RNA engineered to express a selectable marker (e.g., neomycin resistance) instead of a virus-related gene, in this case the structural gene region. A heterologous internal ribosomal entry site (IRES) was inserted to facilitate the expression of nonstructural proteins. This replicon was then inserted into Huh-7 human hepatocellular carcinoma cells and transfected cells were selected. Subsequently, replicons derived from other genotypes (Lohmann's original replicon was genotype 1b) and nonhuman and nonliver cell lines have been P.810 used. It became apparent that replicon RNA developed adaptive mutations that allowed it to replicate efficiently in cell culture and these increased replication manyfold (41). One persistent problem with replicon systems was that they did not release viral particles into the media despite containing the fulllength HCV genome. The reasons for this were not entirely clear, but it appeared that the adaptive mutation that allowed it to replicate in culture prevented virus assembly. Recently, a full-length replicon derived from a genotype 2a isolate from a Japanese patient with fulminant hepatitis was found to replicate in culture without adaptive mutations and produce infectious particles (42). Despite the engineered and artificial nature of these recombinant constructs, these cell-based replicon systems have provided incredible information on HCV replicative mechanisms and they have also proved useful in screening potential therapeutic agents. Figure 30.2 illustrates a simplified view of the infection and replication of the HCV in the hepatocyte (43). The mechanisms of HCV attachment and cell entry are still poorly understood. The envelope proteins E1 and E2 contain several N-linked glycosylation sites that are conserved and critical for cell entry and protein folding (44). E2 on the HCV particle surface binds to the extracellular loop of the human tetraspanin CD81 with high affinity (45). Although CD81 may serve as an essential attachment receptor for HCV, this binding is not sufficient for cell entry and, in fact, it internalizes ligand poorly (46). Other putative receptors that may participate in HCV entry include the LDL receptor (28,47), scavenger receptor class-B type 1 (SR-B1), liver/lymph node–specific intercellular adhesion molecule 3– grabbing integrin (L-SIGN), and dendritic cell–specific intercellular adhesion molecule 3–grabbing nonintegrin (DC-SIGN) (48). Once bound, the viral and cell membranes fuse, the virus is transported into the cell in an endocytotic vesicle whose acid pH uncoats the virus, releasing the positive strand of the

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HCV RNA into the cytosol.

▪ Figure 30.2 Schematic of the intracellular replication cycle of the hepatitis C virus (HCV). Replication takes place within the cytoplasm and is associated with the endoplasmic reticulum membrane. Assembly occurs in the Golgi. RNA, ribonucleic acid; RDRP, RNA-dependent RNA polymerase.

The 5′ end of the HCV genome contains a highly conserved 341-nucleotide region with a complex secondary structure containing four stem loops or hairpins (49). This untranslated region (UTR) contains critical features necessary for replication and initiation of protein synthesis. First, the last stem loop of the 5′ UTR and the initial part of the core gene functions as an IRES, similar to that first described in poliovirus (50,51). Because HCV lacks a 5′ cap, and therefore does not replicate within the nucleus, it requires an IRES to direct and bind it to ribosomal subunits in the cytoplasm to form the translation complex where HCV replication ensues (51,52,53). This causes conformational changes in the ribosome and binding to eucaryotic initiation factor 3 (eIF3) that serves to position the AUG start codon of the viral structural gene at the decoding site of the endoplasmic reticulum membrane. In this way the positivestrand RNA serves as the messenger for translation of viral proteins. The ORF of HCV encodes an uninterrupted stretch of 3,011 amino acids, which contains the viral proteins that are necessary for viral replication. This large polyprotein is processed co- and post-translationally by cellular and viral proteases into numerous polypeptides (Fig. 30.3). The proteins encoded by the gene are, in order from the N terminus, the structural proteins, C, E1, E2, and p7, followed by the nonstructural proteins, NS2, NS3, NS4a, NS4b, NS5a, and NS5b. The structural proteins are encoded by nucleotides in the 5′ third of the genome. Three proteolytic activities mediate the cleavages separating structural from nonstructural proteins (Fig. 30.3). Internal leader sequences within the structural precursor direct precise cleavage of the proteins by host signal peptidases within the rough endoplasmic reticulum (54). The structural proteins are produced in P.811 more than 100-fold excess compared to positive- and negative-strand RNA (55).

▪ Figure 30.3 Hepatitis C virus genome showing protease cleavage sites for corresponding polyprotein. E, envelope; NS, nonstructural; UTR, untranslated region.

The nucleocapsid or core is an unglycosylated basic protein, with RNA-binding capacity controlled by its N terminus and an essential signal for translocation to the endoplasmic reticulum located in the C terminus.

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The core protein modulates cell-signaling pathways, transcription, and transformation through its interactions with host proteins. Its sequence is highly conserved and contains several B-cell epitopes (40). The envelope proteins are highly glycosylated, and some of these glycans play an essential role in protein folding and cell entry (44,56). The proteins are type I transmembrane glycoproteins with tails that serve as endoplasmic reticulum retention signals. They form noncovalently linked heterodimers and disulfidelinked aggregates, the latter being misfolded forms (56). Immune electron microscopic studies have confirmed that these proteins do, indeed, form the structural envelope of the virus (26). Both envelope proteins contain several B-cell epitopes including neutralizing epitopes. The N-terminal residues of E2 exhibit significant amino acid variation between viral genotypes and even within the same host (quasispecies) (57). These variable regions, termed hypervariable regions (HVR1 and HVR2), are highly unstructured and are therefore able to tolerate considerable sequence variation (57). Much of this variability may be the result of immune pressure from neutralizing antibodies. Indeed, HVR1 is expressed on the viral surface, and its variability probably contributes in part to the ability of the virus to escape neutralizing antibodies (58). Studies in chimpanzees appear to confirm this because antibody against E2 confers only transient protection against HCV infection (59). p7 is a small protein that is required for replication and may function as an ion channel (60). In sequence, the nonstructural proteins are then cleaved from the polyprotein. First, the viral autoprotease, a zinc-dependent proteinase encoded by NS2, cleaves the NS2/NS3 junction (61,62). Second, the serine protease, a chymotrypsin-like enzyme encoded by N-terminal third of the NS3 region, cleaves the remaining nonstructural viral proteins at NS3/NS4a, NS4a/NS4b, NS4b/NS5a, and NS5a/5b junctions (Fig. 30.3) (63,64,65). The enzyme is obviously essential to viral replication and contains three highly conserved sites that are thought to represent the catalytic triad of the enzyme (66). The reversible binding of NS4a acts as a cofactor for the protease, allowing the enzyme to assume a more traditional trypsin-like configuration and increasing activity (67). Binding of NS4a to the protease also increases the stability of the enzyme and directs it to the endoplasmic reticulum (68). Interestingly, NS4a from heterotypic isolates can also activate the NS3 protease, although genotype 2 NS4a is a less efficient cofactor (69). In vitro studies have shown that the NS5a/NS5b junction is the most efficiently cleaved site. Protease activity is susceptible to inhibition by its cleavage products (70). The carboxy end of NS3 encodes a nucleotide triphosphatase energy source and another NS3 enzyme, the nucleoside triphosphate-binding RNA helicase, which is thought to facilitate unwinding of the RNA strands during replication (71). The unwinding activities of HCV helicase operate at the 3′ UTR for the generation of the negative-strand RNA replication template and at the 5′ UTR for the production of positive-sense RNA for assembly into infectious viral particles. The NS4 region is cleaved next, producing the NS4a and NS4b proteins. The C terminus of NS4a has been shown to be a cofactor of the NS3 serine protease as described in the preceding text (65,72). It is not essential for the function of the protease but stabilizes it and significantly improves its efficiency (66,67). The function of NS4b has recently been clarified. It produces vesicular structures in hepatocytes that serve as a membranous web or scaffolding for the replication complex (see subsequent text) (73). NS5a is a phosphorylated protein that has been implicated in RNA binding and interferon (IFN) resistance, at least in some P.812 isolates (74). The region has also been found to contain mutations that allow efficient replication of HCV replicons in Huh7 hepatocellular carcinoma cells (41). The NS5b region contains the viral RNA–dependent RNA polymerase that elongates HCV RNA strands during replication (75). The enzyme is produced in excess because only approximately 1% of the total polymerase content appears to participate in replication (76). The nonstructural components assemble with the polymerase to form the membrane-associated replication initiation complex. Host cellular factors are involved with this complex as well. This multisubunit, membrane-associated replication complex is called replicase. The stem loop structures at the 3′ end of the coding region, but not the entire 3′ UTR, are critical for specific binding of NS5b and probably explain the specificity of the HCV polymerase (77). After binding of the 3′ end of the positive strand to the replication complex, the nascent negative– stranded RNA is elongated and the viral helicase helps separate the RNA strands (71). The negative strand of genomic length can then serve as the template for the production of nascent-positive RNA strands, which can be incorporated into the nucleocapsid that is then encoated with the viral envelope to form the mature HCV virion progeny (78,79,80,81). The HCV particles then bud from the hepatocyte. The in vivo dynamics of HCV replication have been investigated in humans. On the basis of these studies, it is estimated that HCV replication results in more than 10 1 2 viral copies per day (82). Because the halflife of these particles is short (about 2.7 hours), there is a turnover of more than 99% of viral particles daily (82). Turnover is slower ( Table of Contents > Volume 2 > Section VI - Alcohol and Drug -Induced Disease > Chapter 32 - Alcoholic Liver Disease

Chapter 32 Alcoholic Liver Disease Srinivasan Dasarathy Arthur J. Mccullough

Key Concepts z

z

Although 90% to 100% of heavy drinkers show evidence of fatty livers, only 10% to 35% develop alcoholic hepatitis and 5% to 15% develop cirrhosis. The daily intake of alcohol that results in liver injury varies and depends on a number of modifiable and unmodifiable factors. Alcoholic liver disease (ALD) develops at much lower doses, especially in women, Hispanics, and patients with hepatitis C infection.

z

Insights into the pathogenesis of alcohol-induced liver injury have improved significantly, but translation into clinical benefit has been slow. Interaction among the products of alcohol metabolism, hepatic parenchymal and nonparenchymal cells, and chemokine release all contribute to the injury and progression of the disease.

z

The importance of continued abstinence and correction of nutritional deficiencies are major components in the long-term management of ALD.

z

Alcoholic hepatitis has a variable mortality and the prognosis is determined most commonly by the modified discriminant function. Further studies are required to establish the prognostic accuracy of the Model for End-Stage Liver Disease (MELD) or the recently described Glasgow alcoholic hepatitis score (GAHS).

z

Anti-inflammatory therapy with corticosteroids and anticytokine therapy with pentoxifylline are effective and are evidence-based therapy for patients with severe alcoholic hepatitis. It may be necessary to perform a liver biopsy in patients with ALD because the clinical diagnosis is not always accurate. This is of particular relevance when corticosteroids are being considered for treating alcoholic hepatitis.

z

Patients with end-stage ALD should be considered for liver transplantation. Six months of abstinence is usually required before transplantation, but this length of time may be adjusted on an individual basis.

z

Liver transplantation is being increasingly offered to patients with alcoholic cirrhosis and the results are similar to those in nonalcoholic patients. Post-transplantation alcohol abuse is a clinical issue that needs to be addressed throughout the pre- and post-transplantation setting. The role of liver transplantation, especially using living donors, for acute alcoholic hepatitis is a matter of debate.

Table 32.1. Characteristics of Alcoholism

Characteristic 1. Tolerance

Clinical feature A state of adaptation in which increasing amounts of alcohol are needed to produce the desired effects

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2. Physical

A typical withdrawal syndrome appears on interruption of drinking,

dependence

which is relieved by alcohol itself or other drugs in the alcohol/sedative group

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3. Impaired control

Total alcohol intake cannot invariably be regulated once drinking has begun at any drinking occasion

4. Craving

A dysphoria of abstinence that leads to relapse

The Acronym TyPICal is suggested as an aid to clinicians to diagnose alcoholism.

P.882 Worldwide, alcohol is the most frequently used and socially acceptable hepatotoxin (1). Geographic patterns of alcohol intake and the prevalence of alcoholic liver disease (ALD) are changing constantly with the rapid increase in per capita alcohol ingestion in eastern European countries and stabilized use in western European countries, Canada, and Australia (2). Approximately two thirds of the adult Americans drink some alcohol (3). Most drink light or moderate amounts and do so without problems (4,5,6,7); however, a subgroup of drinkers become dependent on alcohol and have the disease of alcoholism (8,9). Another group of drinkers are alcohol abusers (and problem drinkers) who experience negative consequences of drinking (e.g., unemployment, loss of family, or accidental injury or death). These patients are not considered to be alcohol dependent (7,10). Failure to recognize alcoholism remains a significant problem that impairs both the prevention and management of ALD (10,11). The clinical features of tolerance, physical dependence, impaired control, and craving that define alcoholism (shown in Table 32.1), as well as their acronym TyPICaL, are suggested as aids to the clinician for making the diagnosis. For more complete and formal diagnostic criteria of alcohol-use disorders, publications by various organizations including the American Psychiatric Association and the World Health Organization are recommended (12,13).

Disease Spectrum Alcohol affects the liver depending on the dose and the duration of use or abuse (14,15,16). The spectrum of alcohol-related liver injury varies from asymptomatic hepatomegaly to profound hepatocellular failure and portal hypertension (17,18,19). Pathologically, this is translated into fatty infiltration of the hepatocytes at the stage of transition of asymptomatic hepatomegaly to frank cirrhosis, with decompensation at the end stage (17,20,21). There are at least five histologic manifestations of ALD, which include fatty liver or steatosis, acute alcoholic hepatitis, chronic hepatitis, hepatic fibrosis, and cirrhosis (22). Of these, chronic hepatitis is a stage that has been reported in ALD, but its diagnosis has been questioned. (23,24). Figure 32.1 displays the different stages and evolution of ALD, and Table 32.2 lists the histologic characteristics and describes their prevalence in the different stages of ALD (22). Fatty liver develops in virtually every individual who drinks more than 60 g/day of alcohol and initially localizes to the perivenular or centrilobular region of the liver (25,26,27). Decreased energy stores due to hypoxia and a shift in lipid metabolism along with a shift in the redox reactions caused by the preferential oxidation of alcohol in zone 3 of the hepatic lobule are the reasons for this localization (Fig. 32.2) (27,28). Simple, uncomplicated fatty liver is usually asymptomatic and considered reversible (29,30). Once fatty infiltration becomes severe, particularly with a mixed (macro-/microvesicular) pattern and associated with giant mitochondria or perivenular fibrosis (26,31), progression to fibrosis and cirrhosis (8% to 20% of patients) can occur. Progression of ALD culminates in scarring and development of cirrhosis (32). Although usually micronodular, it is occasionally mixed micro- and macronodular (19,33). Fibrogenesis is believed to start in the perivenular area and is influenced by the amount of alcohol ingested (26,34). Perivenular fibrosis and deposition of fibronectin occurs in 40% to 60% of patients who ingest more than 40 to 80 g daily for an average of 25 years. However, the thickness of the perivenular fibrosis does not correlate with the amount of alcohol ingested. It should also be noted that the occurrence of the fibrotic features was more than twice the frequency of cirrhosis. Although this may be partly related to sampling error, the disparity between the frequency of fibrosis and the development of cirrhosis suggests that factors other than fibrogenesis are involved in the progression of fibrosis to cirrhosis in patients with ALD (35).

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Figure 32.3 shows the estimated prevalence of the different histologic forms of alcohol-mediated liver injury among heavy drinkers (22). This emphasizes the heterogeneity of the patient populations with regard to disease severity and individual susceptibility to alcohol. Among patients who are heavy drinkers, 90% to 100% will show histologic evidence of fatty liver but only 10% to 35% will develop alcoholic hepatitis and 8% to 20% will develop cirrhosis (36,37).

▪ Figure 32.1 The schematic form of the progression and potential regression among the various histologic stages of alcoholic liver disease. THV, terminal hepatic venule; PT, portal tract.

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Risk Factors Only a minority of individuals who ingest significant amounts of alcohol progress beyond fatty liver and develop alcoholic hepatitis or cirrhosis. Therefore, other factors must play a role in placing these individuals at risk for developing these more severe forms of ALD (30,38). A number of risk factors have been proposed (Fig. 32.4), but none of them can either singly or in combination completely explain the reason why only a minority of individuals ingesting large amounts of alcohol develop ALD (39,40).

Ethnicity Ethnic differences in the prevalence of alcohol-related liver disease and associated mortality have changed with time (2). In the first half of the 20th century, when reporting of mortality was done for whites and nonwhites (composed predominantly of African Americans), the mortality was significantly higher for the former. By the mid-1950s, this reversed and the mortality for nonwhites exceeded that for whites. Later, when data was published for different ethnic groups, a twofold increase in the level of transaminases was found to occur more frequently in Hispanics and Blacks than P.884 in whites (41). Recently, South Asian (Indian) non-Muslim men have been observed to have a higher rate of alcoholic cirrhosis at a younger age and after a shorter duration of alcohol abuse (42). It is not clear whether the ethnic differences are the result of genetic polymorphisms, or quantity or type of alcoholic beverages consumed (2).

Table 32.2. Histologic Characteristics of Alcoholic Liver Disease

Fatty liver

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Alcoholic

Cirrhosis

Cirrhosis– alcoholic

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(%)

hepatitis (%)

(%)

hepatitis (%)

73

97

76

35

0

76

19

95

Megamitochondria

100

32

8

13

Sclerosing hyaline

4

68

3

44

Fibrosis

31

54

100

100

Fat (moderate to severe)

69

82

27

43

Perivenular fibrosis

4.9

19

—

—

Ballooning degeneration with PMNs

Mallory bodies

necrosis

PMN, polymorphonuclear cells. These data were obtained and modified from MacSween RN, Burt AD. Histologic spectrum of alcoholic liver disease. Semin Liver Dis 1986;6(3):221–232.

▪ Figure 32.2 The oxygen gradient between the portal area (zone 1) and the pericentral area (zone 3) of the hepatic lobule. The metabolism of alcohol increases oxygen consumption and causes the largest gradient in zone 3. MEOS, microsomal ethanol-oxidizing system.

Alcohol The quantity of alcohol ingested (independent from the form in which it is ingested) is an important risk factor for the development of ALD (43). A significant correlation exists between per capita consumption and the prevalence of cirrhosis. Epidemiologic evidence exists for a marked reduction in the prevalence of ALD, with diminished alcohol ingestion during war rationing, prohibition, and increased cost. (44,45). Available evidence indicates that there is an increased risk of developing cirrhosis with the ingestion of more than 60 to 80 g/day of alcohol in men and more than 20 g/day in women, when consumed for 10 years or longer (2,16,46). Even in these groups, only 6% to 41% of those drinking at such levels develop cirrhosis (2,16,47). In the Dionysos study, even in patients with

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very high daily alcohol intake (>120 g/day) only 13.5% developed alcohol-induced liver damage (46,48). In addition, disagreement exists on whether the amount of alcohol consumption increases the risk of ALD proportionally. However, population-based data consistently confirm that the quantity of alcohol ingested is a risk factor for ALD (49). In the Dionysos study, the risk of cirrhosis or noncirrhotic chronic liver disease increased with a total lifetime alcohol intake of more than 100 kg or a daily intake of more than 30 g/day (46). The odds of developing cirrhosis or noncirrhotic liver disease with a daily alcohol intake of more than 30 g/day was 13.7 and 23.6, respectively, when compared with nondrinkers.

▪ Figure 32.3 A schematic displaying the percentage of heavy drinkers who develop the different stages of alcoholic liver disease. ?, uncertainty regarding the precise percentage but may be as high as 40%.

There is now increasing evidence that the type of alcohol also determines the risk of development of liver disease (50). In a larger survey of over 30,000 persons in Denmark, beer or spirits were found more likely to be associated with liver disease. It was also observed that in persons who drank heavily, consumption of wine lowered the all-cause mortality (51,52). It is however P.885 unclear whether wine drinking was itself protective or was a surrogate for other healthy behaviors such as consumption of fruits and vegetables (52). Alcoholic beverages that contain a higher content of short-chain aliphatic alcohols have been associated with a high prevalence of liver cirrhosis (53).

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▪ Figure 32.4 The risk factors, which may be cofactors required for the development of advanced alcoholic liver disease.

Another factor that has been identified is the contribution of the pattern of drinking to the development of liver injury. Drinking outside of mealtime has been reported to increase the risk of ALD by 2.7-fold compared to those who consumed alcohol only at mealtime (54). This was not, however, reproduced in a subsequent French study (55). Binge drinking, which may be considered to be a form of outside mealtime drinking, has also been shown to increase the risk of ALD and allcause mortality (56). Binge drinking has also been shown to be associated with degradation of a large quantity of mitochondrial deoxyribonucleic acid (DNA) that contributes to steatohepatitis and reperfusion injury, both of which result in significant damage to the hepatocytes and potentially nonparenchymal hepatic cells (57).

Gender Women have been found to be twice as sensitive to alcohol and develop more severe ALD at lower doses and with shorter duration of alcohol consumption than men (27,58,59,60,61). As compared to men, in whom 80 g of daily alcohol consumption was considered to be a hazardous amount, early data suggested the hazardous level to be 60 g daily in women (62). Because most of those individuals developing ALD ingested more than 35 units/week, a “safe” limit of alcohol intake had been suggested to be 21 units/week in men and 14 units/week in women (62,63). However, more recent data from the Copenhagen City study suggest that a lower quantity, more than 7 units/week, may be toxic in women (49,64). The data in Table 32.3 and Figure 32.5 confirm the association between increased alcohol intake and ALD, the lower threshold toxic dose, and the increased female susceptibility for ALD. On a practical level 1 unit of alcohol (1 ounce of “spirits” [40% alcohol], one 12-ounce beer [5% alcohol], or one 4-ounce glass of wine [12.5% alcohol]) contains approximately 10 g of alcohol for wine and spirits and 14.4 g of alcohol for beer. This is based on a specific gravity of 0.8 for alcohol and the average alcohol content of beer. These amounts may vary depending on the actual alcohol content of beer, which varies significantly among commercial brands (Table 32.4), as well as the size of the pour for wine and spirits.

Table 32.3. Relative Risk of Alcoholic Liver Disease at Different Levels of Alcohol Intake

Alcoholic cirrhosis Weekly units of alcohol

Alcoholic liver disease

Men

Women

Men

Women

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AST usually Table of Contents > Volum e 2 > Section VI - Alcohol and Drug-Induced Disease > Chapter 33 - Drug-Induced Liver Disease

Chapter 33 Drug-Induced Liver Disease Shivakumar Chitturi Geoffrey C. Farrell

Key Concepts z

Over 300 drugs in current use have been implicated in causing liver injury, but there is strong evidence

z

Most implicated drugs cause liver disease in fewer than 1 in 10,000 persons who are exposed, but the

for causality with fewer than 20 of these agents. frequency of hepatotoxicity is influenced by genetic factors, age, gender, intake of other drugs or alcohol, nutritional status, and preexisting liver disease. z

Interactions between drugs and disease-related factors include highly active anti-retroviral treatment (HAART) and hepatitis C virus (HCV) infection, tamoxifen and nonalcoholic fatty liver disease (NAFLD), methotrexate with diabetes and hepatic fibrosis, and antituberculosis drugs with chronic hepatitis B and hepatitis C.

z

The clinicopathologic spectrum of drug-induced liver disease ranges from nonspecific injury to acute and chronic hepatitis, granulomatous hepatitis, cholestatic reactions, vascular lesions, and hepatic tumors.

z

Although characteristic “signature” patterns are observed with some drugs, others are associated with diverse clinical syndromes.

z

Although the liver biochemistry profile may aid initial evaluation, liver biopsy remains the gold standard for defining the type and extent of drug-induced liver disease.

z

Pathogenic mechanisms underlying hepatotoxicity include dose-dependent injury, metabolic idiosyncrasy, and immunoallergic reactions. The latter may be part of the reactive metabolite syndrome, a multisystem disorder with hallmarks of hypersensitivity.

z

Supportive measures remain the cornerstone in managing patients with drug-induced liver disease. Early recognition of drug toxicity and immediate withdrawal of the offending drug are critical. With the exception of N-acetylcysteine, there are no specific antidotes. Corticosteroids are not routinely recommended but may be valuable in select cases showing pronounced hypersensitivity characteristics (e.g., allopurinol). Anecdotal evidence favors the use of ursodeoxycholic acid in the setting of protracted cholestasis. Early consultation with a liver transplantation center is mandatory for individuals developing progressive impairment of liver function.

z

Serial liver test profiles are often recommended to facilitate early detection of liver injury. However, with few exceptions, the sensitivity and cost-effectiveness of this approach remains untested. P.924

z

Clinical evaluation of symptoms that could be drug related is critical in facilitating early detection, and subsequent drug discontinuation is the key to preventing adverse outcomes.

z

Herbal hepatotoxicity and use of recreational drugs (of abuse) should now be considered in the differential diagnosis of all liver disorders.

Introduction Terminology and Definitions Hepatotoxicity is liver injury caused by foreign compounds (xenobiotics). These include prescribed and nonprescribed therapeutic agents (drugs), including herbal medicines, and a vast array of other organic and inorganic substances that may be ingested deliberately or accidentally and that may contaminate the environment, workplace, or home. Therefore, xenobiotics include pesticides, herbicides, plant, fungal, and microbial products, each of which may have toxic and/or carcinogenic properties. The present chapter concentrates on drug-induced liver injury, in which hepatotoxicity is caused by drugs used either in medical practice or those used by individuals for therapeutic, nutritional, or recreational purposes; the latter including drugs of abuse. Although passing reference is made to other hepatotoxins, the interested reader is referred to more detailed texts for a comprehensive coverage of environmental and industrial hepatotoxicity (1,2). Injury to the liver is largely defined by increased blood levels of proteins that are liberated from damaged hepatocytes; a typical example is alanine aminotransferase (ALT). To implicate a drug as the cause of ALT level elevation we need to know that (a) there is no other hepatic process that could account for the test abnormality (e.g., steatosis), (b) the logistics (particularly the temporal relationships) relating drug intake

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and liver test abnormality are consistent and compelling, and (c) elevation of ALT level really means that the liver is injured. There is often a considerable amount of uncertainty in each of these three areas; some practical implications will be dealt with in “Hepatic Adaptation” (physiologic responses by the liver when exposed to drugs) and “Diagnosis”. We have avoided the term hepatic dysfunction in this text because of its confusion between injury, adaptation, and indices that truly reflect the functions of the liver. Likewise, the pathologically meaningless term transaminitis (an ALT level elevation without histologic evidence of liver inflammation or cell damage) is not used. When the presence of a major (fivefold or greater) elevation in the level of ALT clearly indicates liver injury, or when one or more of the functions of the liver are abnormal (e.g., low levels of plasma proteins such as albumin and clotting factors synthesized by the liver or clinicopathologic evidence of impaired bile flow [cholestasis]), it is highly probable that a drug to which the person has been exposed is the cause of liver disease. Ideally, however, definition of drug-induced liver disease requires histopathologic characterization rather than syndromic recognition of liver test abnormalities. Although the distinction between injury and disease is sometimes artificial because they clearly overlap, it is maintained, wherever possible, in this chapter so as to provide insights into the clinical significance of hepatic adverse drug reactions. As new drugs emerge, the evidence that they induce liver injury is often weak and circumstantial; it is sometimes hotly debated because of the implications for further use and marketing of valuable therapeutic agents or for medicolegal implications (3). To partly meet the challenge of possible newer types of druginduced liver disease that are not yet well defined as reproducible entities, we have included a section “Emerging Drugs” at the end of this chapter. Another definitional challenge is that drugs may sometimes alter physiologic parameters that have an impact on hepatic viability. In particular, some drugs can profoundly reduce hepatic blood flow and oxygen delivery, induce hyperthermia, or modify arterial supply to major bile ducts, each of which can result in liver injury that may be minor or profound. Cocaine, general anesthetic agents, alcohol, intra-arterial floxuridine, and “ecstasy” are agents that most likely produce liver injury by such indirect mechanisms rather than by direct hepatotoxicity or adverse drug reactions. Another challenge in defining drug-induced liver disease is the increasing number of circumstances in which drug ingestion appears to contribute to chronic liver disease or hepatic tumors, as discussed in later sections. The lead time (“latent period”) to onset or diagnosis of such associations is many months or years. As a result, repeated observations and case–control studies are essential to ensure that they are not chance associations, while experimental evidence from laboratory or animal studies are desirable to invoke biologically plausible mechanistic explanations for this type of effect of the drug on the liver. Therefore, there is no “gold standard” by which drugs can be proved to have a unique etiologic role in liver disease, particularly because some of the disorders with which they are associated appear very similar or identical to syndromes associated with other causes. P.925 Further, it is increasingly apparent that drugs may interact with each other or with other hepatotoxins (particularly alcohol) as part of interactive hepatotoxicity, as well as with viruses (human immunodeficiency virus [HIV] and hepatitis B and C viruses), immune mechanisms (HIV/acquired immunodeficiency syndrome [AIDS] and bone marrow transplantation), and metabolic factors (nonalcoholic steatohepatitis [NASH]), to accentuate or cause liver injury. Such interactions may be exceedingly difficult to recognize or prove, and nearly impossible to quantify as “relative risk” by conventional epidemiologic techniques. The evidence implicating involvement of drugs in liver injury associated with more complex medical settings is discussed in a later section.

Dose-Dependent Hepatotoxicity and Hepatic Drug Reactions Some agents possess a high degree of intrinsic hepatotoxic potential; they cause dose-dependent liver injury in humans and usually many other species. The history of industrial hepatotoxicity is replete with such examples, among which dimethylnitrosamine, carbon tetrachloride, tetrachloroethane, trinitrotoluene, phosphorus, tannic acid, and vinyl chloride are well known. Some early therapeutic drugs and anesthetic agents (arsenicals, chloroform) have also been assigned to this category, although older studies are inadequate in ascertaining causal mechanisms because viral hepatitis, hepatic perfusion, and tissue oxygenation could not be assessed by contemporary criteria. Among today's drugs, very few are dosedependent hepatotoxins (Table 33.1). For those that are, as illustrated by acetaminophen, it is not the chemical structure of the parent drug that is responsible for liver injury but rather the production of chemically reactive metabolites that interfere with the integrity of the liver. It follows that for most dosedependent hepatotoxins, a range of host factors predicate the amount of reactive (toxic) metabolites that accumulate, thereby determining the risk of liver injury for a given dose of the toxicant. The vast majority (>95%) of drugs implicated as causing drug-induced liver disease are clearly not dosedependent human hepatotoxins, although some of them (usually at high, nonpharmacologic doses) produce experimental liver injury. This relative “intrinsic hepatotoxic potential” tends to be roughly proportional to the risk of liver injury in humans (2); for a few agents there is also evidence that liver injury is partially dose dependent (e.g., perhexiline maleate, herbal medicines, tacrine, dantrolene, cyclophosphamide, sex steroids, and cyclosporine). However, the frequency with which such agents cause liver injury among those exposed is either low or extremely small, ranging from 0.5% to 2% with chlorpromazine and isoniazid (INH), through more typical rates of 1 to 10 cases per 100,000 persons exposed, to even lower rates (e.g., 1 case per 1,000,000 persons exposed) with minocycline, and some of the oxypenicillins and nonsteroidal anti-

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inflammatory drugs (NSAIDs) (Table 33.2).

Table 33.1. Examples of Dose-Dependent Hepatotoxins

z

Acetaminophen (paracetamol)

z

Drugs used in cancer chemotherapy (especially those used with radiotherapy);

z

Amodiaquine

z

Hycanthone

z

Carbon tetrachloride, dimethylnitrosamine, methylenedianiline

z

Plant and fungal toxins: Pyrrolizidine alkaloids, aflatoxin

z

Ethanol

z

Metals: Copper, iron, mercury

z

Bile salts

cyclophosphamide, busulphan, bis-chlorethyl-nitrosourea

It is clear that for these rare, dose-independent, unpredictable, or idiosyncratic drug reactions to occur, it is the host response to the drug that often determines liver injury, not the dose or chemical structures of the agent and its metabolites. Idiosyncratic hepatotoxicity is difficult to reproduce in other species, and it is therefore hard to ascertain the pathogenetic mechanisms involved. Clinical recognition will always remain a challenge because most doctors will never encounter individual reactions or observe them more often than once or twice in a professional lifetime. Two broad types of pathogenic mechanisms could account for idiosyncratic hepatic drug reactions. The first is “metabolic idiosyncrasy,” in which pathways of drug metabolism or disposition favor drug accumulation or formation of toxic metabolites. The underlying determinants include pharmacogenetic variability of drug metabolism and expression of “antistress” and antioxidant cell defense pathways. The metabolic P.926 idiosyncrasy concept now needs to be extended to consider ways in which the liver, a highly adaptable organ, normally counters the “stress” of potentially damaging chemicals. Therefore, using experimental toxicants, it has become evident that foreign compounds, drug metabolites, and resultant oxidative stress can stimulate or interrupt intracellular signaling pathways that converge on the target genes involved in stress responses, cell death, or cell cycle regulation. Alternatively, they may directly activate transcriptional regulators to the same effect or more indirectly interfere with cell integrity and cell death pathways by their interactions with mitochondrial function and integrity; the latter includes the unique “guardian role” of mitochondria for cell survival, as well as in energy generation. As discussed in Chapter 8, drugs can alter the regulation of adenosine triphosphate (ATP)-dependent transporters that actively pump drug metabolites out of liver cells, particularly through canalicular pathways that are physiologically engaged in the generation of bile. Finally, drugs, reactive metabolites, and oxidative stress can interact with the cytoskeletal determinants of cellular transport, receptor signaling, and cell–cell communication (discussed further in Chapter 34).

Table 33.2. Frequencies of Some Types of Idiosyncratic Drug-Induced Liver Diseases

Frequency a

Drugs

5–20/1,000 exposed

Isoniazid, chlorpromazine, dantrolene

1–2.5/10,000 exposed

Estrogen-induced cholestasis

0.5–20/10,000 exposed

Ketoconazole

1–10/100,000 exposed

Diclofenac, sulindac, phenytoin, flucloxacillin

0.5–3/100,000 exposed

Amoxicillin–clavulanate, nitrofurantoin, terbinafine, dicloxacillin

≤1–10/1,000,000 exposed

Minocycline

a

Based on published data referred to in the text.

The alternative pathogenic mechanism underlying idiosyncratic hepatic drug reactions is an “immunoallergic” response. This refers to classical “hypersensitivity” in the sense that repeated exposure results in an

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exaggerated and unhelpful tissue-based or systemic injurious inflammatory response. Immunoallergic reactions are even less well understood than metabolic idiosyncrasy for their role in drug-induced liver disease. The possible immunologic mechanisms are reviewed elsewhere (4,5). Some may be examples of druginduced autoimmunity in which the liver is the principal organ involved, implying that the drug (or its metabolites) induces immune dysregulation (6). Syndromes of chronic hepatitis with hyperglobulinemia and autoantibodies (e.g., with nitrofurantoin, minocycline or diclofenac) are examples of such an immune-based mechanism. There is increasing evidence that, for a subset of reactions, reactive metabolites are involved in recruiting inflammatory mechanisms, either as haptens or with molecular mimicry (7). Regulation of hepatic cytokines may also be important, as shown by studies of drug hepatotoxicity in mice with targeted disruptions of interleukin (IL)-4, IL-10, or cyclo-oxygenase 2 (COX-2) mediators that help prevent allergic hepatitis (5). Recruitment of eosinophils to the liver in the later stages of idiosyncratic drug reactions may depend on the expression of the chemokine, eotaxin (8). It is often not possible to clearly distinguish between these apparently diametrically different causative mechanisms. They may often overlap, particularly because hepatic inflammatory reactions appear to evoke the liver's own innate immunity, as seen by the presence of liver lymphocytes and activated Kupffer cells (resident macrophages). Ultimately, it is most likely that the principal factors predicating idiosyncratic drug reactions are genetically determined (4,9,10,11,12,13); this provides a challenge for future studies directed at prevention and for timely interventions to avoid the adverse clinical outcomes that are unacceptably common for some agents and reactions (see “Improving Outcomes”).

The Importance of Drug-Induced Liver Disease The importance of drug-induced liver disease is summarized in Table 33.3. The pertinent factors are the disproportionate importance and potential preventability of serious hepatic adverse drug reactions in older P.927 people. Some newer aspects include the potential of drugs to produce synergistic hepatotoxicity in persons with, for example, viral hepatitis, HIV/AIDS, and NASH; this is discussed later in relation to interactive hepatotoxicity and interactions with alcohol. The low frequency of reactions for a host of commonly used drugs can delay recognition of drug-induced liver disease; the resultant continued ingestion of the causative agent is the single most important determinant of adverse outcome. In addition to the key responsibility of physicians to make an early diagnosis and stop patients’ exposure to potentially implicated agents, they have moral, ethical, and medicolegal responsibilities to prevent, mitigate, and report iatrogenic disease.

Table 33.3. Factors that Contribute to the Importance of Drug-Induced Liver Disease

z

Approximately 6% of all adverse drug reactions

z

Higher frequency among severe adverse drug reactions

z

Most frequent cause for postmarketing withdrawal of medications

z

Preventable or correctable cause of acute and chronic liver disease

z

Approximately 5% of cases of jaundice or acute hepatitis in the community

z

Higher proportion (10%–40% depending on age) of cases of hepatitis admitted to hospital

z

Important cause of acute liver failure (>50% of cases in the United States; 36% from acetaminophen, 16% idiosyncratic hepatic drug reactions)

z

Common cause of undiagnosed liver injury, particularly among persons aged >50 years.

z

More than 300 currently used drugs cited in literature as potential causes

z

Low frequency of liver injury leads to cases often being overlooked and difficulty in attributing causality

z

One agent may cause more than one pattern of drug-induced liver disease

z

Critical importance of early diagnosis and stopping drug exposure to avoid progression and poor outcomes

z z

Poor understanding of pathogenic mechanisms makes reactions difficult to predict and prevent Role of drugs in synergistic hepatotoxicity with viral hepatitis, nonalcoholic steatohepatitis, human immunodeficiency virus/acquired immunodeficiency syndrome, and bone marrow or organ transplantation

z

Moral/ethical responsibility to prevent or minimize iatrogenic disease

z

Medicolegal implications of this responsibility (informed consent, practice standards, due diligence, etc.)

The increasing number of pharmacologic agents for which adverse hepatic drug reactions have been described is a major challenge for clinicians (2,9,14,15,16,17,18,19,20). In addition to case recognition, this invokes consideration of what level of patient information should be regarded as appropriate at the time of prescribing drugs, and how this information should be imparted to the consumer.

Diversity of Clinical Expression Drugs have become the greater mimickers of “natural” liver diseases. Therefore, hepatic drug reactions range from nonspecific abnormalities of liver tests (which may represent minor degrees of liver injury or hepatic adaptation), through clinicopathologic features of cholestasis, acute hepatitis, and acute liver failure, to more

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exotic syndromes such as hepatic sinusoidal or venous outflow obstruction syndromes, nodular regenerative hyperplasia (NRH), chronic hepatitis resembling autoimmune hepatitis (AIH), hepatic fibrosis, NASH, cirrhosis, and benign or malignant liver tumors. It therefore remains crucial that physicians should always consider a possible drug etiology or some other type of hepatotoxicity, irrespective of the pattern of liver injury. A common pitfall is to impute causality to known causes of liver disease that happen to be present (hepatitis C virus [HCV], alcohol, and gallstones are common “confounders”) in what are actually cases of drug-induced liver disease. Another challenge is the propensity of some drugs to cause more than one clinicopathologic syndrome of liver injury; examples such as oral contraceptive steroids (OCSs), diclofenac, and nitrofurantoin are discussed later.

Epidemiology and Risk Factors Epidemiology In discussing how commonly a drug causes liver injury, it is important to note that the term “incidence” (the number of new cases in a period of time) is not particularly helpful because the onset of adverse drug reactions is nonlinear with time; they tend to occur within the first few weeks or months of treatment. A better descriptor is the proportion of persons exposed to the agent who develop the reaction. This proportion is best described by the frequency of the reaction within the affected group; the latter is expressed ideally as the number of persons exposed, but surrogate estimates are often used, such as the number of prescriptions written or the number of person-years of drug ingestion. Other estimates of the frequency of adverse drug reactions or risk of hepatotoxicity come from prescription event monitoring or record linkage conducted prospectively by health maintenance groups and from case–control studies. More commonly used methods include voluntary (or mandated) reporting of reactions to agencies that monitor adverse drug reactions or drug manufacturers. However, this approach is weakened by the inherent inaccuracies of case definition and the vagaries of case documentation, factors that depend on the skill and motivation of observers. Drugs that carry a high frequency of liver injury are usually recognized as hepatotoxic during phase III trials, which typically involve hundreds or a few thousand persons, or during the first 2 years of postmarketing surveillance (which may involve hundreds of thousands or millions of subjects) (3). Fialuridine, bromfenac, and troglitazone are recent examples of agents withdrawn because of a high frequency of severe liver injury. More often, the recognition of drug-induced liver disease comes several years after the release of a new agent, often with a flurry of case reports, small series, and analyses of larger repositories of information held by drug-monitoring authorities or pharmaceutical companies. More recent examples include amoxicillin– clavulanate, oxypenicillins, diclofenac, sulindac, and troglitazone (21,22,23). Such “miniepidemics” serve principally to highlight how often early reactions to the implicated agents may have been overlooked, or they evolve from massive prescribing of the vigorously marketed new drugs; the latter phenomenon is illustrated by hepatic reactions to flucloxacillin in Australia, where the number of prescriptions written per million people greatly exceeded that of any other country (24). Reliable information about the risk of liver injury is available for less than 20 of the 300 or so currently used drugs that have been implicated as possible or likely causes of drug-induced liver disease. Some of these data are summarized in Table 33.2. It is reiterated here that a significant issue confounding the epidemiology of this type of disorder is the lack of diagnostic accuracy in defining cases of drug-induced liver disease. As discussed in the next section, this depends entirely on probabilistic evidence surrounding the onset of the P.928 reaction and its resolution or recurrence in relation to drug exposure, the elimination of other known causes of similar hepatobiliary disease, and occasionally on ancillary evidence of an adverse drug reaction. When drugs contribute to but are not the unique cause of liver disease, it may be possible to assign a relative risk for this complication. This has been attempted in the case of OCS and liver tumors (25,26), OCS and hepatic venous outflow obstruction (27) (see Chapter 40), aspirin and Reye's syndrome (28), and methotrexate and hepatic fibrosis among those who drink appreciable quantities of alcohol (29). Future attempts at providing similar semiquantitation of the risks of drug-induced hepatotoxicity within “high-risk” scenarios should be directed at the use of antiretroviral agents for HIV/AIDS, and tuberculosis or cancer chemotherapy among persons with chronic hepatitis B or C infection.

Risk Factors for Incidence and Severity The factors that increase the risk of drug-induced liver injury may include dose, duration of treatment, blood levels, age, gender, coincidental metabolic disorders or genetic predisposition to hypersensitivity reactions, concomitant exposure to other drugs or environmental agents, and underlying liver disease. Some examples are summarized in Table 33.4, while further details are given in later sections concerned with individual drugs. A recurring theme is the relationship between failure to recognize a given drug as the possible cause of the patient's symptoms, the resultant failure to discontinue exposure to that drug, and subsequent development of severe hepatotoxicity, often with liver failure and lethal consequences.

Table 33.4. Risk Factors for the Incidence and Severity of Drug-Induced Liver Diseases

Risk factor

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Representative agents

Importance

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Age

Gender

Isoniazid, nitrofurantoin,

Age >60 y increases frequency

halothane, troglitazone

and severity

Valproic acid, salicylates

More common in children

Halothane, minocycline,

More common in women,

nitrofurantoin,

especially chronic hepatitis

dextropropoxyphene

Amoxicillin–clavulanate,

More common in men

azathioprine

Dose

Acetaminophen; some herbal

Risk of hepatotoxicity depends

medicines

on blood levels

Anticancer drugs; perhexiline,

Partial relationship to dose

tacrine, oxypenicillins, dantrolene

Methotrexate, vitamin A

Total dose, dose frequency, and duration of exposure influence risk of hepatic fibrosis

Genetic factors

Halothane, phenytoin,

Multiple cases in families, in

sulfonamides

vitro test results

Amoxicillin–clavulanate

Strong human leukocyte antigen association

Valproic acid

Familial cases, association with mitochondrial enzyme deficiencies

Other drug reactions

Isoflurane, halothane,

Cross-sensitivity reported

enflurane

between these classes of drugs

Erythromycin, other macrolide antibiotics Diclofenac, ibuprofen Sulfonamides, cyclooxygenase 2 inhibitors

Concomitant drugs

Acetaminophen

Isoniazid, zidovudine, and phenytoin lower hepatotoxic dose threshold and increase severity

Valproic acid

Other anticonvulsants increase risk

Excessive alcohol use

Acetaminophen hepatotoxicity

Lowers dose threshold, worsens outcome

Isoniazid, methotrexate

Increases risk of liver injury, hepatic fibrosis

Nutritional status

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Obesity

Halothane, tamoxifen,

Increases risk of liver injury,

methotrexate

nonalcoholic steatohepatitis, or hepatic fibrosis

Fasting

Acetaminophen

Increases risk of hepatotoxicity

Hycanthone, pemoline

Increases risk of liver injury

Antituberculosis

Increases risk of liver injury with

chemotherapy, ibuprofen

chronic hepatitis B and C

Diabetes mellitus

Methotrexate

Increases risk of hepatic fibrosis

Human immunodeficiency

Sulfonamides (cotrimoxazole)

Increases risk of hypersensitivity

Tetracycline, methotrexate

Increases risk of liver injury,

Liver disease

Other diseases

virus/acquired immunodeficiency syndrome

Renal failure

hepatic fibrosis

Organ transplantation

Azathioprine, thioguanine,

Increases risk of vascular

busulfan

toxicity

P.929

Genetic factors It seems likely that host predisposition to idiosyncratic hepatic drug reactions is genetically determined (10,11,12,13). The relatively small number of instances in which familial clustering has been documented may reflect the dual requirements for altered expression of relevant genes and for exposure to particular drugs; halothane, OCS cholestasis, valproic acid (VPA), and phenytoin reactions are those for which more than one case has occured in the same family (14). Phenytoin is an example of the reactive metabolite syndrome (RMS) pattern of severe skin reactions often associated with systemic involvement, among which drug-induced liver disease is common (30). Some of the causative agents, risk factors, and clinical features are summarized in Table 33.5. Individuals have a 25% likelihood of developing adverse drug toxicity if a first-degree relative has experienced a similar reaction; the chances are even higher with other risk factors such as HIV/AIDS, systemic lupus erythematosus (SLE), and antecedent intake of VPA or corticosteroids (Table 33.5). In addition to determining the expression and inducibility of CYP pathways of drug oxidation, conjugation reactions, and antioxidant enzymes (see Chapter 34), genetic factors encode ATP-dependent pathways of drug elimination from hepatocytes, through the canalicular membrane into bile or through the basolateral membrane into sinusoidal blood (31,32). Regulation of the immune response (presumably including hepatic innate immunity) is also genetically determined, and other critical genes encode the structure of the cytoskeleton, heat shock proteins, and cellular resistance against activated cell death pathways. These are all variables in the pathogenesis of drug-induced liver injury (see Chapter 34). Characterization of the genes that are involved in hepatic reactions to clinically relevant agents provides an outstanding challenge in the field of drug-induced liver disease, as reviewed elsewhere (5). The likelihood that more than one “abnormality” (e.g., genetic polymorphisms, extreme variation) is required before tissue-destructive responses occur would explain the rarity of most reactions. It is already known that inherited defects of mitochondrial metabolism clearly predispose to valproate hepatotoxicity (33) (See “Valproic acid (sodium valproate)”), and there are strong associations between human leukocyte antigens (HLAs) and cholestatic drug reactions to amoxicillin– clavulanate and tiopronin (34,35,36). Weaker associations between HLA molecules and particular types of drug hepatitis have also been reported (37).

Age and sex The frequency and severity of hepatic drug reactions both increase with age (Table 33.4). The explanations are likely to be multifactorial and include increased exposure; higher probability of multiple drug therapy; biologic effects of aging on drug disposition, especially altered hepatic uptake as the result of decreases in blood flow; and/or diffusion of drugs across the hepatic microvasculature into hepatocytes (38). Some of the many examples of drug reactions that are more common in older people are listed in Table 33.4. Conversely, a small number of drug-induced liver diseases P.930

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are more common in children, particularly those that involve mitochondrial injury, such as VPA hepatotoxicity and Reye's syndrome.

Table 33.5. The Reactive Metabolite Syndrome and Hepatic Drug Reactions

Drugs implicated

Risk factors

Clinical and laboratory features

z

Sulfonamides

First-degree relative with

z

Onset: 1–6 wk (up to 12 wk)

z

Clozapine

serious rash to same

z

Sentinel symptoms: Fever,

z

Anticonvulsants

drug (one in four risk),

pharyngitis, malaise, headache,

(e.g., phenytoin,

or metabolically cross-

periorbital edema, otalgia/

lamotrigine,

reacting drug

headache, mouth ulcers,

phenobarbital, z

z z

z

z

rhinorrhea

Human immunodeficiency

carbamaze pine)

virus/acquired

Some nonsteroidal

immunodeficiency

Stevens-Johnson syndrome,

anti-inflammatory

syndrome (100-fold

toxic epidermal necrolysis,

drugs

increased risk)

Aminopenicillins Chinese herbal

z

medicines

Systemic lupus erythematosus (10-fold increased risk)

z

Serious rash: Erythematous,

erythema multiforme z

z

Lymphadenopathy (16%), splenomegaly Hepatic reactions: Cholestasis, hepatitis, granulomas (13%)

z

Quinolones

z

Protease inhibitors

starting drug (4.4-fold

z

Nephritis (9%)

(e.g., nevirapine,

increased risk)

z

Pneumonitis (6%)

Valproic acid at time of

z

Hematologic (neutropenia,

abacavir)

z

z

Corticosteroids at time of

z

Allopurinol

starting new

z

Minocycline

anticonvulsant (4- to 10-

z

thrombocytopenia) (5%) Encephalitis/meningitis (5%)

fold increased risk)

z

Myositis (4%)

z

Colitis (2%)

z

Arthritis, transient hypothyroidism

z

Blood tests: Neutrophilia (shift to left); atypical lymphocytes, acute-phase reactants (early); eosinophilia (often late)

Women are more likely than men to develop drug-induced hepatitis after exposure to nitrofurantoin, sulfonamides, diclofenac, minocycline, troglitazone, and halothane. Chronic hepatitis caused by the first four of these agents (and historically with methyldopa and oxyphenisatin) has an even higher (80% to 90%) female predominance. Some cholestatic reactions are more common in men (Table 33.4); these include amoxicillin– clavulanate- and azathioprine-induced vascular injury in transplant recipients. The reasons for sex differences in some hepatic drug reactions remain unclear.

Exposure to other drugs and toxins Patients taking more than one agent have an increased risk of adverse drug reactions, including drug-induced liver disease (14,39,40,41,42,43). Particularly relevant examples include acetaminophen, INH, VPA, and anticancer drugs (44). A possible relationship between agents that alter canalicular bile pathways has also been indicated, including interactive hepatotoxicity between OCS and other drugs to produce prolonged cholestatic reactions (45). Chronic excessive intake of ethanol is a risk factor for hepatotoxicity with acetaminophen, INH, nicotinamide, and methotrexate.

Nutritional status Fasting predisposes to acetaminophen hepatotoxicity because of its effects on drug conjugation and oxidation pathways, as well as on hepatic glutathione (GSH) levels. It has also been proposed that malnutrition increases the risk and severity of hepatotoxicity from drugs used to treat tuberculosis (46), but controlled studies are lacking. Overnutrition (obesity) increases the risk of halothane hepatitis. The increased risk of NASH and hepatic fibrosis among those taking methotrexate, estrogens, tamoxifen, or corticosteroids (Table 33.4) is discussed later.

Past history and other medical disorders Instances of cross-reactivity to similar agents are reported with haloalkane anesthetics (e.g., halothane, enflurane, isoflurane), INH and pyrazinamide, sulfonamides and some COX-2 inhibitors, some NSAIDs, and macrolide antibiotics. Such cross-reactivity is surprisingly uncommon, but a history of any previous adverse drug reaction increases the risk of drug-induced liver injury to other agents. It is again emphasized that a previous reaction to the same drug is the single most important factor predisposing to unusual severity of

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drug-induced hepatitis (e.g., acute liver failure, chronic liver disease). Renal failure predisposes to methotrexate-induced hepatic fibrosis and tetracycline-induced fatty liver, while renal and other solid organ transplantation is a risk factor for hepatic vascular injury with azathioprine. Likewise, disorders associated with hepatic venous outflow obstruction, such as veno-occlusive disease (VOD) (now termed the sinusoidal obstruction syndrome [SOS]; the terms VOD and SOS are used interchangeably in this chapter), are attributed to cancer chemotherapeutic agents prescribed during bone marrow transplantation (as well as with radiotherapy) (47). Rheumatoid arthritis, and possibly SLE, appears to increase the risk of salicylate hepatotoxicity and sulfasalazine-induced hepatitis. The risk of drug reactions (including hepatitis) to both sulfonamides and sulfones is greatly increased among persons with HIV/AIDS and also in SLE (Table 33.5), while diabetes (as well as obesity, alcohol, renal failure, and preexisting liver disease—see subsequent text) predisposes individuals to hepatic fibrosis during methotrexate therapy.

Preexisting liver disease Early studies of chlorpromazine, halothane, and methyldopa reactions clearly demonstrated that other liver disorders, including alcoholic cirrhosis and cholestatic liver diseases, did not predispose to these archetypical examples of idiosyncratic drug hepatitis. On the other hand, for a few agents in which partial dose dependency or metabolic mechanisms appear likely, preexisting liver disease may be a risk factor for incidence and severity of drug-induced liver disease (Table 33.4). These drugs include nicotinamide (niacin), hycanthone, pemoline, and some anticancer drugs (48,49,50,51). The risk of methotrexate-induced hepatic fibrosis is also increased in the presence of other forms of liver disease (52). More recently, interactions between inflammatory forms of liver disease, particularly chronic viral hepatitis, and accentuation of liver injury have been described, including an apparently heightened risk of reactions to antituberculosis chemotherapy, ibuprofen, flutamide, cyproterone acetate, and highly active anti-retroviral treatment (HAART) (53,54,55,56,57,58,59).

Toward Better Outcomes Prevention Given the central role of the liver in drug metabolism and disposition, and the rarity of most types of liver injury with what are otherwise valuable therapeutic agents, it is impossible to completely prevent all cases of drug-induced liver disease. General approaches to P.931 primary prevention include appropriate use of drugs (nonpharmacologic approaches whenever possible, optimal choice of agents based on efficacy and safety, case selection, avoiding polypharmacy where possible, avoiding excessive dosage), restricted availability and blister packaging of over-the-counter medication (See “Acetaminophen”) (60), physician and public education about possible drug side effects and about how to recognize and what to do about them, and monitoring for adverse drug reactions. Conveying appropriate recommendations about dose limitations for agents such as acetaminophen, nicotinamide, and complementary and alternative medicines (CAMs) would prevent many instances of liver injury. Careful adherence to dosage guidelines (or use of blood levels) has virtually abolished methotrexate-induced hepatic fibrosis (See “Methotrexate”), tetracycline-induced mitochondrial injury, and aspirin hepatitis. Avoiding repeated halothane administration within 28 days or in people with suspected previous halothane sensitivity would prevent many cases of this serious form of drug-induced hepatitis. For select agents with known hepatotoxicity, and particularly when treatment is likely to extend for longer than 2 to 4 weeks, it may be appropriate to first establish that the liver test results are normal before starting treatment and then estimate liver tests (liver function test [LFT]) or conduct other safety monitoring during therapy. However, although such “LFT monitoring” is often suggested as one approach to prevent serious outcomes of drug-induced liver disease (particularly by authors of single case reports and by manufacturers who share liability in litigation cases), there is little evidence to support this as a general policy (61,62). Therefore, the high costs and inconvenience of such screening, the need to determine appropriate testing intervals (4 weeks is usually too long for agents that can cause acute liver failure), the weak specificity of abnormal results for identifying serious hepatotoxic potential, and the difficulty of defining a threshold at which the drug should be discontinued all thwart the logistics of monitoring drug treatment with liver tests. It particularly needs to be appreciated that 7.5% of subjects receiving placebo in clinical trials have persistently raised ALT levels (63). In the absence of symptoms, it is difficult to specify a level of ALT abnormality at which treatment should be discontinued. It is generally recommended that the drug should be stopped if ALT exceeds five times the upper limit of normal (ULN) (approximately 250 U/L), but any abnormality of serum bilirubin or albumin concentration or prothrombin time and the presence of any symptoms are clear indications to stop therapy. In practice, there are few agents for which liver test monitoring is strongly endorsed (see also later sections); these include methotrexate, INH, etretinate and other synthetic retinoids, ketoconazole, anticancer drugs, and prolonged therapy with minocycline. Conversely, the “statins” (β-hydroxy-β-methylglutaryl-coenzyme A reductase inhibitors) are a group of commonly used drugs that rarely cause significant liver injury (62,64), and for which the recommendation (by the manufacturers) for LFT monitoring is now being seriously questioned.

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Management The most important aspect is early recognition and discontinuation of the putative causative agent. At each visit, patients should be warned to report any untoward new symptoms, and particularly fever, systemic symptoms (malaise—“I don’t feel these tablets agree with me, doctor”; see also the sentinel symptoms listed in Table 33.5), anorexia, nausea, and vomiting. If patients present after jaundice has developed, it is often too late to avoid a severe reaction because of the potential for developing liver failure or prolonged cholestasis. When patients report symptoms of a possible drug reaction, physicians should immediately check liver test results to establish whether there has been a change from baseline; in cases of doubt, the agent should be discontinued. After drug discontinuation, most adverse drug reactions will resolve spontaneously, rapidly, and completely, but this is not always the case. Drugs with a prolonged half-life are particularly associated with protracted hepatic drug reactions. Amiodarone, etretinate, ketoconazole, and hypervitaminosis A are examples, but delayed resolution of liver injury can occur with several other drugs on some occasions. In case of severe reactions, hospitalization is advisable, and further evaluation is carried out if the diagnosis is unclear. Otherwise, relief of symptoms is all that is required. As for any type of hepatic injury, older age carries an increased risk of severe liver injury. Repeated vomiting, deepening jaundice, and development of even subtle laboratory or clinical features of liver failure are indications for admission. Transfer to a liver failure unit should be considered and/or discussions with a liver transplant team should be initiated before the patients decline into hepatic coma, or have bleeding from coagulation disorder, sepsis, and hepatorenal failure. In cases of dose-dependent hepatotoxicity, approaches to management include testing for drug levels and monitoring the clinical condition of the poisoned person. Attempts to remove unabsorbed drug by aspiration of stomach contents should be considered for agents such as acetaminophen, metals, and toxic mushrooms; other approaches (administration of charcoal or other resins or osmotic cathartics) are generally unlikely to be effective, although they have been advocated P.932 for poisoning with toxic mushrooms (65). Likewise, approaches to remove residual drug from the body, such as using chelating resins for drugs with an enterohepatic circulation (66) or by hemodialysis, passage of blood through charcoal columns, or forced diuresis are not effective for most hepatotoxins. Acetaminophen hepatotoxicity is the only drug-induced liver disorder for which a specific antidote (Nacetylcysteine [NAC]) is available (67). Two agents that have been proposed to control protracted hepatic drug reactions are corticosteroids and ursodeoxycholic acid. There are few clear guidelines for their use, and the evidence of efficacy is confined to uncontrolled reports among individual cases or in small series. Older studies with corticosteroids found limited or no efficacy among cases of severe drug hepatitis for methyldopa, iproniazid, INH, chlorpromazine, halothane, phenytoin, and oxyphenisatin (14). More recent observations indicate occasional responses, particularly when drug-induced liver injury is associated with vasculitis (e.g., allopurinol, sulfonamides) and in some (but not all) cases of drug-induced chronic hepatitis (14). A pragmatic approach is to observe the course for 3 to 6 weeks after stopping the drug (unless there is evidence of further deterioration), reserving corticosteroids for cases in which there is failure to show clinical or biochemical improvement or in which the differential diagnosis between AIH and drug-induced chronic hepatitis remains in doubt. Some experienced clinicians still favor a short course of corticosteroids (“steroid whitewash”) to hasten recovery in persons with prolonged drug-induced cholestasis. If the mechanistic basis for such efficacy can be established (stimulating reexpression of the canalicular transporters responsible for bile flow would be a possible example), a firmer conceptual basis or more appropriate pharmacologic agents to stimulate a clinical resolution may become possible. Meanwhile, corticosteroids have a range of unpleasant or severe side effects, and our preference would be to use ursodeoxycholic acid (15 mg/kg body weight) in such cases. There is a reasonable body of uncontrolled data to indicate that approximately two thirds of such cases will respond with reduction of pruritus and other symptoms and acceleration of biochemical improvement. Ursodeoxycholic acid is safe, well tolerated, and has been used with occasional success in patients presenting with cholestatic liver injury attributed to amoxicillin–clavulanate, flucloxacillin, and flutamide (68,69,70,71), as well as cyclosporine (which is not a form of cholestasis) (72). Other approaches to treating pruritus are discussed (73) in Chapter 24. During prolonged cholestatic reactions, fat-soluble vitamin deficiency should be corrected.

Diagnosis of Drug-Induced Liver Disease Diagnosis of drug-induced liver disease is always presumptive because it is based on a logistic approach rather than on absolute criteria and specific diagnostic tests. As a result, there will be varying degrees of certainty about the diagnosis, depending on the strength of supporting evidence. In estimating the likelihood of diagnosis (“causality assessment”) (74,75), evidence is sought by first determining whether the link between drug ingestion and liver injury is plausible, then by excluding other disorders and seeking the presence of any positive features of adverse drug reactions, and finally by assessing features indicative of the liver histology. Attempts have been made to compile these lines of evidence into diagnostic “scales” that give weight to various features (76,77). Regrettably, these fall down in relation to less common or atypical types of druginduced liver disease, which are those most difficult to diagnose. They have particular limitations for cases with a long delay between the start of drug ingestion and recognition of liver injury (74,77).

Clinical Suspicion

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Some situations in which drug-induced liver disease may be particularly likely are summarized in Table 33.6. In such cases, meticulous attention should be paid to the drug history, returning to it as a special investigation, with consideration of nonprescribed medications, CAM, and environmental toxins. It may be pertinent to direct inquiry to other members of the household and primary care providers and to examine all medications being taken or even the contents of drug cupboards, bedside tables and lockers, and so on.

Time of Onset in Relation to Drug Ingestion Dose-dependent hepatotoxins usually produce overt evidence of liver injury within hours or a few days (See “Acetaminophen”). For adverse hepatic drug reactions, there is a latent period between commencing the drug and the development of symptoms and/or abnormal liver test results. With immunoallergic types of drug hepatitis, granulomatous hepatitis, and drug-induced cholestasis, this is within 4 months (most typically 2 to 10 weeks) in more than three quarters of cases. Occasionally, liver injury becomes evident only after the drug is stopped; for amoxicillin–clavulanate this may be up to 6 weeks after discontinuation. With other types of drug hepatitis (presumed to be instances of metabolic idiosyncrasy), the latent period to onset tends to be a little longer, often between 6 and 26 weeks, and with drug-induced chronic liver disease (e.g., chronic hepatitis, steatohepatitis, and syndromes related to P.933 vascular injury), drug exposure may be for 6 months or longer than 1 year before clinical onset is apparent.

Table 33.6. Some Situations in which Drugs are a Particularly Likely Cause of Liver Disease

z

The person has started new treatment (including CAM) in last 3 to 6 m

z

Presence of extrahepatic manifestations, especially rash, lymphadenopathy, eosinophilia (see also Table 33.5)

z

Acute hepatitis not readily accounted for by hepatitis viruses, other infections, or metabolic or immunologic disorders

z

There are atypical features of liver disease—mixed “hepatocellular and cholestatic” reactions, hepatitis with microvesicular steatosis

z

Cholestasis with normal bile duct caliber on hepatobiliary imaging

z

Cholestasis after common causes have been excluded, particularly in the elderly

z

Histologic features suggest drug-induced liver disease (see text) in cases of cholestasis or acute hepatitis, and hepatitis with hepatic granulomas

z

Chronic hepatitis without autoantibodies or hyperglobulinemia

z

Abnormal liver tests in complex medical situations

z

Obscure or poorly explained liver disease among those taking sex steroids, immunosuppressive agents, or other drugs (including CAM) for years

CAM, complementary and alternative medicine.

Exploring the chronologic relationships between drug ingestion and the onset and resolution of liver injury is the most important consideration in the diagnosis of drug-induced liver disease, as discussed elsewhere (74,75,78).

Repeated Drug Ingestion Some drugs almost never cause liver injury after first exposure, but the risk of hepatotoxicity increases with each subsequent treatment course. Halothane, dacarbazine, and nitrofurantoin are recognized examples. For a much broader range of compounds, a personal history of previous reaction to the drug (inadvertent rechallenge) is common among those with severe or prolonged liver injury; INH, NSAIDs, Chinese herbal medicines, germander, and chaparral are typical examples. To provide stronger evidence of causality, deliberate rechallenge has been used in the past, employing a single and smaller than usual dose of the suspected hepatotoxin; it has proved particularly valuable to incriminate agents not previously known to be associated with liver injury and to identify which agent is responsible when the person has been taking more than one potentially hepatotoxic drug. A positive response (connoted by a recurrence of fever or other symptoms and/or a twofold increase of ALT or serum alkaline phosphatase [SAP] levels) (78) strongly implicates the drug in causing liver injury. However, the practical application of rechallenge is greatly limited by safety considerations; it should never be conducted without the fullest consideration by both the persons involved and their family, and should be done with reference to an Institutional Human Ethics Review Board. Particularly, it should be noted that deliberate rechallenge is potentially dangerous and should never be attempted for the types of reactions listed in Table 33.5.

Response to Discontinuation of the Drug Dechallenge should be followed by improvement in liver test results within days or weeks of stopping the drug; some guidelines have been provided (78). As for time to onset, there are clear exceptions to this generality. Therefore, in cases of liver disease caused by agents such as ketoconazole, troglitazone, coumarol,

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etretinate, amiodarone, and minocycline, severe reactions may resolve slowly (months), or incompletely, with further decline of hepatic function (e.g., troglitazone). Although some instances of drug-induced cholestasis can also be prolonged, failure of jaundice to resolve in case of suspected hepatic drug reactions more often indicates that an alternative diagnosis (e.g., malignant biliary obstruction) has been missed.

Clinical Features Although the clinicopathologic syndrome associated with exposure to a particular drug may be a useful aid to diagnosis, the diversity of reactions to individual drugs is such that absence of the “drug signature” (or “syndromic recognition”) test should not be used to exonerate a given drug as the cause of liver injury. In most respects, the clinical features of drug hepatitis or drug-induced cholestasis are not dissimilar from those found with other causes of these disorders. However, identifying specific risk factors for hepatotoxicity (e.g., prolonged fasting or chronic excessive alcohol intake by a person regularly taking acetaminophen) or the presence of extrahepatic features of drug hypersensitivity (Table 33.5) may suggest the correct diagnosis.

Exclusion of Other Disorders It is critical to exclude other liver diseases before attributing liver injury to drugs (Table 33.7). In an earlier work (79), approximately two thirds of reactions reported as drug-induced chronic hepatitis were subsequently ascribed to chronic hepatitis C. Contemporary P.934 serologic, viral, immunologic, and imaging tests have facilitated the early diagnosis of most acute viral, vascular, and metabolic liver disorders. Likewise, the cause of cholestasis, and particularly mechanical obstruction of the biliary tract, is usually easy to identify with modern imaging (see Chapter 8). Approaches to make the correct diagnosis of a drug reaction when the clinical and laboratory features resemble AIH include the course of the disease after discontinuation of the drug and the patient's response to a short course (4 to 6 weeks) of corticosteroids if there is not rapid improvement after stopping the drug. If there is impressive response to the patient's condition with corticosteroids, followed by relapse after reducing the dose, it allows the physician to assume that the case is actually one of AIH.

Table 33.7. Drug-Induced Liver Disease is a Diagnosis of Exclusion: Consider the Following

z

Hepatitis viruses: Serology and molecular virology (especially hepatitis C virus ribonucleic acid)

z

Other infectious agents: Epstein-Barr virus, cytomegalovirus, human immunodeficiency virus, herpes simplex virus, Coxiella burnetii

z

Autoimmune hepatitis: Antinuclear antibodies, smooth muscle antibodies, liver/kidney microsomal antibodies, immunoglobulin G levels

z z

Acute biliary obstruction, exclude cholangitis Metabolic disorders—Wilson disease, α 1 -antitrypsin deficiency, risk factors for nonalcoholic fatty liver disease/nonalcoholic steatohepatitis (serum lipids, fasting blood glucose or abnormal glucose tolerance test, insulin, C peptide, family history of diabetes, features of the insulin resistance [metabolic] syndrome)

z

Vascular disorders of liver; risk factors, imaging with vascular phase (see Chapter 8)

z

Alcohol

z

Bacterial infection

z

Hepatic metastases

z

Systemic malignancy or lymphoma

Liver Biopsy Liver biopsy plays a special role in excluding other hepatobiliary disorders, but it may also provide positive evidence to corroborate drug-induced liver injury. Biopsy is most strongly indicated when the cause of liver disease remains in doubt; for example, there may be ambiguous evidence of autoimmunity or the pattern of reaction may be very unusual or not previously reported for the drug in question. Details such as whether continued treatment with this medication is highly desirable and whether there is rapid improvement after stopping the drug may influence the decision of performing liver biopsy. As for any indication, the justification for liver biopsy must satisfy the question “Does the likelihood that this procedure will make a difference to the management of the person justify the inconvenience, discomfort, and risks of the procedure?” Informed consent is clearly mandatory, and it may be valuable to document in the medical record (or on a signed consent form) why the biopsy is considered valuable in this particular case.

Table 33.8. Histologic Changes that may Indicate Drug-Induced Liver Disease

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z

Zonal lesions, including necrosis and/or steatosis

z

Microvesicular steatosis (often results from mitochondrial injury)

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z

Necrotic lesions of disproportionate severity of the clinical picture

z

Mixed hepatitis and cholestasis

z

Destructive bile duct lesions

z

Prominent neutrophils and (in later stages) eosinophils (>25%)

z

Granulomas

z

Vascularity of hepatic tumors—sinusoidal dilatation, peliosis

z

Vascular lesions

z

Florid steatohepatitis—resembles alcohol-related steatohepatitis more than typical “primary” nonalcoholic steatohepatitis

There are no histologic features that are pathognomonic for drug-induced liver disease, and indeed some, such as the presence of occasional eosinophils, are often overinterpreted. Nonetheless, some patterns of hepatic lesions may suggest, to an experienced liver pathologist, that a drug or toxin could be implicated (Table 33.8). The reader is referred to the excellent detailed illustrations found in texts such as Hall (80) and Zimmerman (2), as well as earlier editions of this book.

Specific Diagnostic Tests As reviewed elsewhere (5,9), there are no completely validated specific tests for any type of drug-induced liver disease. Interesting data have been presented about the relative specificity of some drug-induced autoantibodies, including anti-M6 (antimitochondrial antibodies [AMAs]) with iproniazid, anti-LKM-2 (against CYP 2C9) with tienilic acid, anti-CYP 1A2 with dihydralazine, and anti-CYP 2E1 with halothane. A test that detects antibodies against trifluoroacetylated (TFA) proteins has been advocated for halothane and other haloalkane-related hepatotoxicity (see later section). However, all such tests have minimal applicability in clinical practice because of their unavailability and lack of standardization, including agreement on what comprises a significant titer of antibodies. P.935

Identifying One Causative Agent Among Many Having established with near certainty that one or more drugs are responsible for an individual case of liver disease, an additional challenge may be to identify which among several is the guilty party. In general, the drug started most recently before the onset of liver injury is the one most likely to be responsible; new and nonproprietary medicines should also heighten suspicion. Otherwise, the drug with the most hepatotoxic track record becomes the prime contender. Whenever possible, all therapeutic agents, or all potential hepatotoxins, should be discontinued. If the patient's condition and laboratory test results improve, the drug(s) that seem(s) unlikely to be responsible can be carefully reintroduced.

Clinicopathologic Syndromes of Drug-Induced Liver Disease The initial “labeling” of cases with apparent drug-induced liver injury has relied heavily on the profile of liver test abnormalities (Table 33.9) and not histopathology, which provides a more definitive classification. It is noted here that the clinical and laboratory features are not always congruent with the liver pathology, and there is much overlap between categories. Therefore, although the histologic changes usually mirror the biochemical abnormalities, certain caveats should be borne in mind. First, alteration of liver enzymes is not synonymous with liver injury and can represent hepatocyte adaptation (see subsequent text). Second, liver tests may underestimate the severity of liver disease, as with the fairly modest changes in levels of aminotransferases (ATs) that may accompany acute liver failure from drug-induced microvesicular steatosis. Conversely, drugs such as estrogens can sometimes be associated with a major increase in ATs despite bland cholestasis on biopsy, while other agents (e.g., methotrexate, vinyl chloride, arsenic) can cause cirrhosis with minimal or no change in biochemical tests of liver disease. Third, the pattern of liver tests is most often mixed or relatively nonspecific, and this occurs with granulomatous hepatitis, steatohepatitis, cholestatic hepatitis, chronic hepatitis, and minor nonspecific patterns of liver injury. A relatively simple approach to clinicopathologic classification of drug-induced liver disease is outlined in Table 33.10.

Hepatic Adaptation Many drugs induce abnormal liver test results without causing symptoms or biochemical evidence of significant liver disease. Minor elevations in the levels of ALT may be transient. In reality, these may indicate minor degrees of nonprogressive injury to key organelles such as mitochondria or cell membranes, without causing cell death and without recruiting an inflammatory response. The nonprogression (and often resolution) of these changes may result from induction of protective processes, such as antioxidant and antiapoptotic pathways; in this sense, minor forms of chemical liver injury are probably often followed by adaptation of the liver to withstand continuing or more substantial insults. Experimental work has demonstrated the hepatoprotective effects of a small dose of carbon tetrachloride against subsequent massive poisoning and the

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phenomenon of ischemic preconditioning that substantially abrogates subsequent ischemic or reperfusion injury; the mechanisms of these adaptive processes are of potential importance in the understanding of druginduced liver disease. Other forms of “hepatic adaptation” include drug-induced hyperbilirubinemia, as observed with agents such as rifampicin, flavaspidic acid, and cyclosporine, and “induction of hepatic enzymes.” Drug-induced hyperbilirubinemia is best understood as a direct interference with pathways of bilirubin uptake, conjugation, and canalicular excretion into bile. Sustained elevation of levels of enzymes such as γ-glutamyl transpeptidase P.936 (GGTP) and SAP is seen with phenytoin and other anticonvulsants, rifampicin, alcohol, and warfarin. Because such agents induce hepatic CYP enzymes, this phenomenon is often referred to as microsomal enzyme induction; the actual relationships between the activity of drug oxidases and the increased plasma levels of these nonmicrosomal enzymes are less clear. Potential explanations are that the indirect effects of increased CYP enzyme activity on bile acid metabolism produce more “detergent” metabolites that liberate these enzymes from the hepatocyte plasma membranes or stimulate increased synthesis of alkaline phosphatase and GGTP; there is some evidence that both these mechanisms may apply. The important clinical point is to clearly recognize the difference between these biochemical changes and cholestasis; for example, serum bile acid levels increase with cholestasis or liver injury but not with hepatic adaptation.

Table 33.9. Definition of Patterns of Liver Injury

Liver injury

Hepatocellular

ALT >2–3 × ULN

Cholestatic

Mixed

ALT >2–3 × ULN

SAP >2 ×

ALT >2–3 ×

and normal SAP

ULN

ULN and SAP >2 × ULN

or

or

or

>2 × ULN conjugated bilirubin or elevated

ALT/SAP ratio ≥5 a

ALT/SAP

ALT/SAP ratio a

ratio ≤2 a

between 2 and

aspartate aminotransferase, SAP, and total

or

bilirubin (one of these must be >2 × ULN)

5

levels

Note that these patterns are a relatively poor guide to the histologic nature of liver disease (see text). a

The ALT and SAP values are expressed as multiples of the upper limit of normal.

ALT, alanine aminotransferase; SAP, serum alkaline phosphatase; ULN, upper limit of normal.

Table 33.10. Clinicopathologic Classification of Drug-Induced Liver Disease

Category Hepatic adaptation

Description No symptoms; raised GGTP and

Examples Phenytoin, warfarin, rifampin

SAP (occasionally ALT) levels

Hyperbilirubinemia

Rifampin

Dose-dependent

Very short interval to onset;

Acetaminophen, nicotinic acid,

hepatotoxicity

symptoms of hepatitis; zonal,

amodiaquine

bridging, and massive necrosis; ALT >5 × ULN, often >2,000 U/L

Other cytopathic liver injury;

Acute steatosis

Microvesicular steatosis, diffuse or

Valproic acid, didanosine, highly

zonal; partially dose dependent;

active anti-retroviral treatment,

severe liver injury; features of

fialuridine, L-asparaginase, some

mitochondrial toxicity (lactic

herbal medicines, ecstasy

acidosis, pancreatitis)

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Acute hepatitis

Chronic hepatitis

Onset within 1–20 wk; sentinel

Isoniazid, dantrolene,

symptoms of hepatitis; focal,

nitrofurantoin, halothane,

bridging, and massive necrosis;

sulfonamides, phenytoin,

ALT >5 × ULN; extrahepatic

disulfiram, etretinate,

features of drug allergy in some

ketoconazole, terbinafine,

cases (Table 33.5)

troglitazone

Duration >3 m; interface hepatitis,

Nitrofurantoin, etretinate,

bridging necrosis, fibrosis,

diclofenac, minocycline,

cirrhosis; clinical/laboratory

mesalamine

features of chronic liver disease; autoantibodies in some cases

Granulomatous hepatitis

Hepatic granulomas with varying

Allopurinol, carbamazepine,

hepatitis and cholestasis; raised

hydralazine, quinidine, quinine

ALT, SAP, GGTP levels

Steatohepatitis

Onset delayed (6–18 m); steatosis,

Perhexiline, amiodarone,

focal necrosis, Mallory's hyaline,

tamoxifen, toremifene; rarely

pericellular fibrosis, cirrhosis;

nifedipine, diltiazem

chronic liver disease, portal hypertension

Cholestasis without hepatitis

Cholestatic hepatitis

Cholestasis, no inflammation; SAP

Oral contraceptives, androgens,

>2 × ULN

cyclosporin A

Cholestasis with inflammation;

Chlorpromazine, tricyclic

symptoms of hepatitis; raised ALT

antidepressants, erythromycins,

and SAP levels

amoxicillin/clavulanate, angiotensinogen-converting enzyme inhibitors

Cholestasis with bile

Bile duct lesions and cholestatic

Chlorpromazine, flucloxacillin,

hepatitis; clinical features of

dextropropoxyphene, carmustine,

cholangitis

paraquat

Chronic cholestasis

Cholestasis present >3 m

Chlorpromazine, flucloxacillin,

Vanishing bile duct

Ductopenia; resembles primary

trimethoprim- sulfamethoxazole

syndrome Sclerosing

biliary cirrhosis but

(Table 33.14)

cholangitis

antimitochondrial antibodies

Intra-arterial floxuridine,

absent

intralesional scolicidals

duct injury

Strictures of large bile ducts

Vascular disorders

Sinusoidal dilatation, peliosis,

Anabolic steroids, oral

noncirrhotic portal hypertension,

contraceptives, vinyl chloride,

nodular regenerative hyperplasia,

Thorotrast (Table 33.14)

sinusoidal obstruction syndrome (veno-occlusive disease)

Liver tumors

Focal nodular hyperplasia, hepatic

Anabolic steroids, oral

adenoma, hepatocellular

contraceptives, vinyl chloride,

carcinoma, angiosarcoma

Thorotrast (Table 33.14)

ALT, alanine aminotransferase; GGTP, γ-glutamyl transpeptidase; SAP, serum alkaline phosphatase; ULN, upper limit of normal.

A morphologic or ultrastructural consequence of microsomal enzyme induction by drugs is the presence of ground glass cytoplasm in hepatocytes, as seen by light microscopy. This results from hypertrophy of the endoplasmic reticulum, which can be confirmed by electron microscopy.

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Drug-Induced Acute Hepatitis Many drugs are associated with acute hepatocellular injury (Table 33.11). There is a latent period between starting treatment and onset of symptoms or liver test P.937 abnormalities; this tends to be shorter (2 to 6 weeks) for agents clearly associated with immunoallergic mechanisms (see Table 33.5) and more variable and longer for those presumed to be due to metabolic idiosyncrasy. Onset is often with prodromal features of fever, malaise, and other “sentinel symptoms” (Table 33.5), followed by rash, lymphadenopathy, or other systemic features of drug hypersensitivity. Clinical features that resemble acute viral hepatitis soon follow, or they may be the presenting symptoms; anorexia, nausea, vomiting, and lassitude are prominent among these. Jaundice is present in severe cases. AT levels are raised (Table 33.9) proportionately more than those of SAP. Serum bilirubin concentration and indices of hepatic synthetic function such as prothrombin time and serum albumin concentration are variably altered depending on the severity and duration of liver injury.

Table 33.11. Drugs Associated with Acute Liver Failure

ANALGESICS/NONSTEROIDAL

CARDIOVASCULAR

NEUROPSYCHIATRIC DRUGS

ANTI-INFLAMMATORY DRUGS

DRUGS

Carbamazepine

Acetaminophen a

Amiodarone

Chlormethiazole

Bromfenac b

Captopril

Felbamate

Diclofenac

Ecarazine

Lamotrigine

Etodolac

Enalapril

Nefazodone

Ibuprofen

Lisinopril

Pemoline

Leflunomide

Labetalol

Phenytoin

Nimesulide

ENDOCRINE DRUGS

Tacrine

Oxaprozin

Carbimazole

Tetrabamate

Piroxicam

Propylthiouracil

Tolcapone

Tienilic acid

Troglitazone b

Topiramate Valproic acid

ANTIMICROBIAL DRUGS

ENVIRONMENTAL

ONCOTHERAPEUTIC DRUGS

Amoxicillin–clavulanate

AGENTS

Carboplatin

Ciprofloxacin, ofloxacin,

Carbon tetrachloride a

Chlorambucil

Mushroom poisoning a

Cyproterone acetate

Cotrimoxazole

GASTROINTESTINAL

Flutamide

Dapsone

DRUGS

Gemcitabine

Fialuridine b

Ebrotidine

Imatinib mesylate

Flucloxacillin

Omeprazole

MISCELLANEOUS DRUGS,

Highly active antiretroviral

Ranitidine

INCLUDING HERBAL MEDICINES

treatment

GENERAL

AND SELF-ADMINISTERED

Isoniazid, rifampin, pyrazinamide

ANESTHETICS

AGENTS

Ketoconazole, itraconazole

Halothane

Allopurinol

Lamotrigine

Enflurane

Chaparral a

Minocycline

Isoflurane

Cocaine a

trovofloxacin

Sulfonamides (many)

Disulfiram

Terbinafine

Germander

Tetracycline (intravenous)

Herbal slimming aids Hydrazine sulfate Interferon-α, interferon-β a Kava 3,4Methylenedioxymethamphetamine (“ecstasy”) Nicotinic acid a Zafirlukast

a

Dose-dependent hepatotoxicity.

b

Withdrawn.

The histologic lesions consist mainly of focal hepatic necrosis, with apoptotic (acidophil) bodies and a mixed inflammatory infiltrate. Bridging necrosis is present in severe cases and may lead to chronic hepatitis if the causative agent is not withdrawn. Zonal necrosis is a typical feature of more severe forms of liver injury caused by drugs and other chemical or plant toxins. Zone 3 lesions (centrilobular or perivenular) are seen with acetaminophen and carbon tetrachloride toxicity but can also occur in acute SOS (or VOD). The overrepresentation of zone 3 lesions in

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cases of drug-induced liver injury is related to the high metabolic activity of this zone, which generates reactive metabolites. By comparison, isolated zone 1 (phosphorus or iron poisoning) and zone 2 lesions (cocaine toxicity) are extremely rare. Severe acute hepatitis may culminate in acute liver failure; massive or submassive hepatic necrosis is often present. Acetaminophen (See “Acetaminophen”) is the leading cause of drug-induced acute liver failure worldwide, but regional differences exist. Other drugs that have been associated with acute liver failure are listed in Table 33.11. P.938

Mitochondrial Injury Fatty liver (steatosis) can be seen in the vicinity of zonal necrotic lesions but may also be the predominant manifestation. Microvesicular steatosis is a severe form of hepatotoxicity that results from mitochondrial injury; decreased numbers of mitochondria are often found. There is often evidence of other organ involvement, particularly pancreatitis, nephrotoxicity, encephalopathy, and metabolic acidosis. The clinical syndrome resembles acute fatty liver of pregnancy (see Chapter 46). Patients present with nausea, vomiting, abdominal pain, and rapidly evolving encephalopathy. Liver biopsy specimens show accumulation of small fat droplets (microvesicular steatosis) in hepatocytes in a zonal or diffuse distribution. Biochemical features include profound hepatocellular dysfunction with hypoglycemia, coagulopathy, hyperammonemia, and lactic acidemia. There may be a rise in serum bilirubin and AT levels, but these are less pronounced than in other forms of acute hepatotoxicity or hepatitis. Historically, this syndrome was associated with the use of tetracycline in pregnant women, Reye's syndrome (see Chapter 46) caused by the use of aspirin in febrile young children with influenza B and some other viral infections, and with sodium valproate in very young children with predisposing factors (see later section). Currently, the most important cause is HAART, and particularly the nucleoside inhibitors, but amphetamine analogs used recreationally, especially ecstasy, and buprenorphine misuse can produce similar lesions (81). The drugs associated with microvesicular steatosis are listed in Table 33.12. Unlike acute microvesicular steatosis, drug-induced steatohepatitis is a type of hepatocellular injury associated with chronic liver disease. Hepatic decompensation can occur, and some drugs associated with steatohepatitis have also been implicated as causing acute liver failure. In general, however, progression to cirrhosis or liver complications is slower. Drugs associated with steatohepatitis are listed in Table 33.13. The histologic features are indistinguishable from those of alcoholic steatohepatitis, with varying degrees of steatosis, focal lobular inflammation with polymorphonuclear cells, hepatocellular necrosis, and Mallory bodies. Excluding ethanol abuse is critical, but the changes also resemble those found in NASH (see Chapter 39). Therefore, some associations between the drugs used for complications of the metabolic syndrome (e.g., diabetes, high arterial blood pressure, cardiac failure) and steatohepatitis may be fortuitous, while other agents (e.g., corticosteroids, estrogens, tamoxifen) may exacerbate NASH because of effects on insulin resistance and lipid turnover. Drug-induced steatohepatitis often causes hepatic fibrosis in the pericentral (perivenular or acinar zone 3) and pericellular distribution; this distribution is typical for all other causes of steatohepatitis. Cirrhosis can develop and eventually lead to hepatic decompensation.

Table 33.12. Drugs Associated with Microvesicular Steatosis

Aspirin (Reye's syndrome in febrile children) a Fialuridine b Highly active antiretroviral treatment Industrial toxins—dimethylformamide, selenium Nonsteroidal anti-inflammatory drugs—ibuprofen, piroxicam, pirprofen, tolmetin b Riluzole Tetracycline (historical) Tetrabamate (Atrium) Ticlopidine Valproic acid Vitamin A

a

Declining incidence since health warnings have been issued on the use of aspirin in young children.

b

Withdrawn.

Table 33.13. Drugs Associated with Steatohepatitis

Amiodarone Coralgil (4,4-diethylaminoethoxyhexestrol) a Estrogens b

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Glucocorticosteroids b Perhexiline maleate Methotrexate Methyldopa b Nifedipine b Tamoxifen Toremifene Verapamil b

a

Withdrawn.

b

More likely to be a fortuitous association resulting from association with risk factors for “primary”

nonalcoholic steatohepatitis (see text).

Cholestasis There are several different syndromes of drug-induced cholestasis (Table 33.14) (82,83). Bland cholestasis occurs without symptoms of hepatitis. Liver biopsies show intrahepatic cholestasis without significant hepatic inflammation. This syndrome is associated with oral contraceptive use and occurs more often in women with a family or personal history of cholestasis of pregnancy (see Chapter 46). Pruritus is often troublesome, but jaundice is less common. Recovery is the rule, but complete resolution can be protracted in some cases. In cholestatic hepatitis, liver histology shows lobular and portal tract inflammation, as well as cholestasis. As with other forms of drug hepatitis, clinical onset is with flu-like symptoms, but this is soon followed by features P.939 of hepatitis, such as anorexia, vomiting, jaundice, and right hypochondrial pain. The latter can be severe and misinterpreted as acute cholecystitis. Drugs that cause cholestatic hepatitis can also cause bile duct injury; dextropropoxyphene (84) and methylenedianiline (an epoxy resin hardener associated with cases of liver injury or jaundice after industrial exposure or food contamination, the latter called most infamously as the Epping jaundice) cause a striking syndrome of cholangitis (85). Cholangiolytic (interlobular bile duct) injury is prominent in many cases of drug-induced cholestatic hepatitis, and when lesions are severe enough this can lead to ductopenia or the vanishing bile duct syndrome (VBDS).

Table 33.14. Clinicopathological Syndromes of Drug-Induced Cholestasis

Clinical and laboratory features

Type

Examples

ACUTE FORMS

Cholestasis without

Prodromal symptoms, then

Estrogens, anabolic steroids, tamoxifen,

hepatitis (“bland”

intense pruritus; SAP >3 × ULN;

azathioprine

cholestasis)

AT rise is often transient (rarely >3–5 × ULN); bilirubin 3 × ULN in 70%, AT >2–5 ×

piroxicam), captopril, enalapril,

ULN

azathioprine

Cholestasis with

Resembles acute cholangitis

Dextropropoxyphene, flucloxacillin,

bile duct injury a

(often with cholestatic hepatitis)

paraquat, methylenedianiline

(cholangiolytic)

CHRONIC FORMS

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Vanishing bile duct

Chronic cholestasis, resembles

Chlorpromazine, flucloxacillin, and other

syndrome (Table

primary biliary cirrhosis but

oxypenicillins

33.15)

antimitochondrial antibodies absent

Large bile duct

Chronic cholestasis, resembles

Floxuridine, intralesional scolicides (2%

strictures (similar

sclerosing cholangitis (but

formaldehyde, hypertonic saline, iodine

to sclerosing

strictures at junction of right

solution, absolute alcohol, silver nitrate)

cholangitis)

and left hepatic ducts)

a

Several drugs implicated in causing cholestatic hepatitis may also produce bile duct injury.

AT, aminotransferase; SAP, serum alkaline phosphatase; ULN, upper limit of normal.

Table 33.15. Drugs Associated with the Vanishing Bile Duct Syndrome

Amoxicillin–clavulanic acid a

Flucloxacillin a , dicloxacillin

Ampicillin

Glycyrrhizin (a component of Chinese herbal

Amitriptyline, imipramine

medicines)

Azathioprine

Gold

Barbiturates

Haloperidol

Carbamazepine a

Ibuprofen

Chlorothiazide

Itraconazole

Cotrimoxazole a

D-Penicillamine

Clindamycin

Phenytoin a

Chlorpromazine a

Prochloperazine a

Cimetidine

Tetracycline a

Cyproheptadine

Terbinafine

Erythromycin esters a

Thiabendazole

Estradiol, norandrostenolone,

Tiopronin

methyltestosterone a

Tolbutamide

Original references can be obtained from refs 2,14,67,83,86. a

More than one reported case.

The VBDS is characterized by progressive destruction of segments of the biliary tree (82). Over 30 drugs have been implicated (82,86,87,88,89,90,91) but those with highest risk of this outcome after drug-induced cholestatic hepatitis are chlorpromazine (7% of cases), oxypenicillins (particularly flucloxacillin [10% to 30% of cases]), and erythromycins (5% of cases) (92) (Table 33.15). The main predictor of VBDS after cholestatic hepatitis may be the initial severity of bile duct damage (87). The clinical features resemble those of primary biliary cirrhosis (PBC) with jaundice, with liver test results indicating cholestasis, hypercholesterolemia, xanthomas, and other manifestations of chronic cholestasis. However, unlike PBC, AMAs are usually absent. Hepatic fibrosis is not usually prominent, but biliary cirrhosis can sometimes develop. Resolution may take up to 2 years and is sometimes incomplete. Large duct bile duct lesions (“sclerosing cholangitis”) are an uncommon type of drug-induced injury. Wellcharacterized historical examples include intra-arterial floxuridine infusions (which cause an ischemic cholangiopathy) and intracavitary instillation of scolicidal agents (82,93). Current practices of targeted chemotherapy for hepatic malignancy and ultrasound-guided scolicidal therapy have a low risk of drug-induced biliary injury. P.940

Granulomatous Hepatitis Hepatic granulomas are associated with numerous infective, inflammatory, vasculitic, and neoplastic disorders (94) (see Chapter 52). Older studies found that approximately one third of cases of hepatic granulomas were attributable to drugs (95), and it seems likely that drugs remain an important cause of “granulomatous hepatitis.” In drug reactions, granulomatous hepatitis may be the sole manifestation of liver injury, but more commonly granulomas accompany other histologic features and represent one of several patterns of hepatic response to injury. Therefore, granulomas have been described with many drugs that are better known for other types of pathology, especially acute hepatitis (e.g., nitrofurantoin, methyldopa, halothane), but also cholestatic hepatitis (chlorpromazine, phenylbutazone, carbamazepine) and steatohepatitis (e.g., amiodarone, calcium channel blockers) (Table 33.16).

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The clinical presentation is indistinguishable from other causes or idiopathic granulomatous hepatitis (see Chapter 52). Therefore, profound lethargy, fever, night sweats, rigors, myalgia, and weight loss are prominent. There is tender hepatomegaly and the spleen is enlarged in 25% of cases. Other extrahepatic manifestations include rashes, particularly a form typifying small vessel vasculitis, lymphadenopathy, and bone marrow granulomas (14). Serum ALT level is often raised, but typically less than that of SAP and GGTP. Jaundice is much less common than that with other types of drug-induced acute hepatitis but has been observed when cases overlap with cholestatic hepatitis; carbamazepine and hydralazine are examples. Withdrawal of the offending drug leads to rapid resolution in most cases. A short course of corticosteroids may hasten recovery in special circumstances, particularly in cases associated with vasculitis or other extrahepatic complications such as interstitial nephritis; allopurinol and sulfonamides are examples.

Drug-Induced Chronic Hepatitis Chronic hepatitis is defined by persistence of symptoms and biochemical or histologic abnormalities for longer than 3 months (14). All drugs implicated as causing chronic hepatitis have also been associated with acute reactions. Continued ingestion of the drug beyond the phase of acute hepatitis is one of the key factors leading to the development of chronic hepatitis, cirrhosis, and liver failure. Early recognition and timely withdrawal of the offending drug are therefore crucial. A distinctive type of drug-induced chronic hepatitis resembling AIH is described. This probably occurs through the process of drug-induced immune dysregulation. The relatively few agents that cause this type of liver disease include nitrofurantoin, diclofenac, methyldopa, and minocycline. More than 80% of reported cases occur in women. Characteristic features include fever and arthralgia in addition to symptoms of chronic hepatitis and signs of chronic liver disease, hypergammaglobulinemia, and antinuclear and/or smooth muscle antibodies (SMAs). A second pattern of drug-induced chronic hepatitis is characterized by autoantibodies directed against specific hepatic microsomal proteins (e.g., tienilic acid, halothane). However, yet other agents (e.g., etretinate and germander) can be associated with chronic hepatic inflammation and liver cell injury (hepatitis) in the absence of autoantibodies or other features of autoimmunity. Finally, a picture of classical AIH may emerge after an episode of drug-induced acute hepatitis. It is unclear whether the emergence of AIH is related to unmasking of latent AIH or whether the drug may directly induce AIH in susceptible persons.

Table 33.16. Drugs Associated with Hepatic Granulomas

ANTIMICROBIALS

ANALGESICS/NONSTEROIDAL

ANTIEPILEPTICS

MISCELLANEOUS,

Amoxicillin–

ANTI-INFLAMMATORY DRUGS

Carbamazepine a

INCLUDING

clavulanate

Aspirin

Chlorpromazine

HERBAL

Cephalexin

Acetaminophen

Phenytoin a

MEDICINES

Dapsone

Clometacin

ENDOCRINE

Allopurinol a

Dicloxacillin,

Phenylbutazone a

DRUGS

Chaparral

oxacillin

CARDIOVASCULAR DRUGS

Chlorpropamide

Gold

Isoniazid

Amiodarone

Methimazole

Glibenclamide

Mebendazole

Diltiazem

Glibenclamide

Halothane

Nitrofurantoin

Disopyramide

Tolbutamide

Interferon-α

Norfloxacin

Hydralazine a

Mesalamine

Penicillin G,

Methyldopa

Methotrexate

penicillin V

Procainamide a

Rosiglitazone

Pyrazinamide Quinine a

Quinidine a

Tacrine Tetrabamate

Sulfonamides

Ticlopidine

(many) a

a

Well-characterized examples with causality proved. Note that the high frequency with which hepatic

granulomas are found in liver biopsies is such that other associations may be fortuitous.

P.941

Hepatic Fibrosis Hepatic fibrosis may be the end result of chronic hepatitis, chronic hepatotoxicity, steatohepatitis, or chronic cholestasis with bile duct injury. However, some drugs and chemicals such as methotrexate, vitamin A, and arsenic can provoke an intense fibrotic reaction without a prominent inflammatory response. With these agents, other profibrogenic risk factors, especially ethanol but possibly also obesity, diabetes, insulin resistance, and iron overload, can accelerate the rate of fibrogenesis (discussed later in relation to vitamin A and methotrexate).

Vascular Lesions Drugs and chemicals are the most important cause of vascular lesions of the liver. The latter include histologic

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curiosities, such as sinusoidal dilatation, to clinically important disorders, such as peliosis hepatis, SOS (VOD), the Budd-Chiari syndrome, NRH, and other causes of noncirrhotic portal hypertension (Table 33.17). Causative drugs include sex steroids, alkylating chemotherapeutic agents (such as cyclophosphamide, busulfan, melphalan, dactinomycin), and immunosuppressive agents (azathioprine). In current practice, SOS (or VOD) most often occurs in the setting of bone marrow transplantation, but in the past it was synonymous with pyrrolizidine alkaloid hepatotoxicity resulting from ingestion of brewed herbal tea mixtures (“Jamaican morning sickness”) (96) or from plant alkaloid contamination of herbal medicines such as comfrey (97). Epidemics of VOD have also been reported in areas where pyrrolizidine alkaloid–contaminated wheat flour had been consumed, particularly in south Asia and the Middle East. Hepatic vein and portal vein thrombosis can occur in OCS users, although latent or overt myeloproliferative disorders or inherited procoagulants states (such as factor V Leiden) (98) are usually also found in cases of venous thrombosis at these sites (see Chapter 40).

Hepatic Neoplasms Drugs and toxins are a rare cause of liver tumors (see Chapters 42 and 43), but some associations exist, as exemplified by OCS and hepatic adenomas. OCS use is recorded in over 80% of patients with these adenomas, and there is a strong relationship between adenomas and the dose and duration of estrogen therapy (25,99,100). In addition, evidence of estrogen dependence of these tumors is evident; regression occurs in a significant proportion of patients after discontinuing OCS (101). As discussed later, surgery is still required in most cases. The relationship between estrogens and focal nodular hyperplasia (FNH) is more complex and less clear etiologically (See “Oral contraceptive steroids”). As for cavernous hemangiomas, sex steroids, and particularly estrogens, may have trophic effects on these two benign hepatic neoplasms, and particularly on their vascularity, although this remains controversial (102); estrogens cannot, therefore, be regarded as the primary causative factor. Malignant tumors such as hepatocellular carcinoma (HCC) are caused by chronic viral hepatitis in more than 80% of cases (see Chapter 43), but in parts of Africa and Asia ingestion of aflatoxin-contaminated or other fungal toxin–contaminated food may play a synergistic role in carcinogenesis. Estrogens increase the risk of HCC in long-term OCS users, but this effect is weak and is overwhelmed in importance by chronic hepatitis B virus (HBV) and HCV infection in regions endemic for these viruses (26). Angiosarcoma is an uncommon liver tumor that was classically associated with the radiocontrast agent Thorotrast (see Chapter 43), vinyl chloride monomer, arsenic, and rarely, androgen use.

Table 33.17. Drug-Induced Vascular Disorders and Tumors

Examples VASCULAR DISORDERS

Peliosis hepatis

Anabolic steroids, azathioprine, oral contraceptives, 6-thioguanine, Thorotrast

Hepatic sinusoidal obstruction syndrome (venous

Oral contraceptives, pyrrolizidine alkaloids,

outflow obstruction, including veno-occlusive

6-thioguanine, dacarbazine, gemcitabine

disease)

Noncirrhotic portal hypertension

Vitamin A, methotrexate, arsenic, vinyl chloride, azathioprine

Nodular regenerative hyperplasia

Azathioprine, 6-thioguanine, busulfan

TUMORS

Hemangioma

Oral contraceptives (trophic effect on preexisting lesions only)

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?Oral contraceptives (see text)

Hepatic adenoma

Oral contraceptives, anabolic steroids

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Hepatocellular carcinoma

Anabolic steroids, danazol, oral contraceptives, Thorotrast, vinyl chloride

Angiosarcoma

Vinyl chloride, thorium dioxide, arsenic

?, recent data refute existing views of a possible association with oral contraceptives.

P.942

Role of Drugs in Multifactorial Liver Disease Viral Hepatitis Patients with chronic hepatitis B or C may be at increased risk of liver injury during chemotherapy for tuberculosis, with cancer chemotherapy, and after intake of ibuprofen and possibly other NSAIDs (56,57,58). A common problem involves the patient who regularly attends the liver clinic with mild-to-moderate ALT level elevation associated with chronic viral hepatitis, who then presents with an ALT level greater than 300 U/L. Particularly for chronic hepatitis C, changes due to hepatotoxic drugs (56) are more likely than spontaneous fluctuations of disease severity; drugs are almost always the cause with ALT values that greatly exceed 1,000 U/L. A common culprit is acetaminophen taken in moderate daily dosage over a period when there are factors such as concomitant medication, prolonged fasting, or chronic alcohol excess (see later section). Another frequent scenario is the patient who has tried Chinese herbal medicines or some other form of CAM.

Highly Active Antiretroviral Treatment Abnormal liver test results and clinical evidence of liver disease are common in patients with HIV/AIDS. Contributory factors include chronic hepatitis B or C, hepatobiliary infections and infestations, lymphoma and other tumors, and possibly direct effects of HIV infection (see Chapter 51). However, the most common cause of liver injury is hepatotoxicity from drugs used to treat HIV/AIDS. When monotherapy was used against HIV, individual nucleoside analogs were associated with uncommon episodes of severe cytopathic liver injury, as illustrated later for didanosine. In clinical studies, zidovudine and didanosine have been most often implicated in hepatotoxicity, but no particular nucleoside or nucleotide analog appears more hepatotoxic. As discussed later, it seems likely that drug combinations that include protease inhibitors and nucleoside/nucleotide analogs are more toxic than individual agents.

Bone Marrow Transplantation As discussed in Chapter 60, hepatobiliary complications of hematopoietic cell transplantation are common, are often serious, and may be multifactorial in origin. Bone marrow transplantation particularly increases the risk of vascular complications, such as VOD and NRH. Therefore, although SOS (or VOD) causes complications in at least 1% of cases during the use of anticancer drugs, the risk of developing this complication can be as high as 54% after bone marrow transplantation, depending on the regimen used (103,104,105). Of 103 patients undergoing bone marrow transplantation in one series, NRH was present in 23% and SOS (VOD) in 9% (106). The clinical features are similar to those of portal hypertension, often complicated by bleeding esophageal varices and ascites. Hepatic encephalopathy can occur after an episode of severe upper gastrointestinal hemorrhage. Liver test results may be normal or show minor nonspecific changes. The diagnosis is made histologically, although a wedge biopsy may be necessary. In general, the prognosis for NRH is good; complete reversibility may occur in some drug-induced cases (106).

Metabolic Syndrome and Nonalcoholic Steatohepatitis Steatohepatitis is a form of chronic liver disease in which fatty change is associated with focal liver cell injury, Mallory's hyaline, inflammation with mixed cellularity including polymorphonuclear cells, and progressive hepatic fibrosis in a pericentral and pericellular distribution (see Chapter 39). While alcohol is a common etiology, NASH can be associated with diabetes, obesity, and several drugs (e.g., perhexiline maleate [107] and amiodarone [108]). Among drugs associated with steatohepatitis during the 1990s and the 21st century, causality is harder to prove because NASH is such a common disorder among patients with insulin resistance or metabolic syndrome (see Chapter 39). Therefore, calcium channel blockers used for arterial hypertension have been associated with steatohepatitis (109,110), and methyldopa has been reported to cause cirrhosis in obese middle-aged women (111); these associations may be fortuitous. Other drugs, including estrogens (112), tamoxifen, and glucocorticosteroids, may precipitate NASH because of their effects on the metabolic risk factors: Insulin

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resistance, type 2 diabetes, obesity, and hypertriglyceridemia.

Postoperative Jaundice Drug-induced liver disease is a common cause of postoperative liver disease. The differential diagnosis of cases with jaundice is considered in Chapter 25. It is usually easy to distinguish underlying hepatobiliary disorders and bilirubin transport abnormalities resulting from tissue hypoxia or systemic infection (“benign postoperative cholestasis” or “jaundice in sick patients”) resulting from drug reactions. Halothane-induced liver injury is one of the classic types of hepatic drug reactions but has become much less common now that halothane has been almost completely P.943 replaced (in some countries) with equally acceptable and less hepatotoxic agents. Other than halothane, which causes a typical “signature syndrome,” few anesthetics cause significant liver injury. Some cases have been attributed to isoflurane; the evidence and practical implications are discussed in a later section. Postoperative liver injury is also observed with antibiotics (especially amoxicillin–clavulanate, less commonly synthetic penicillins or cephalosporin derivatives), analgesics (particularly acetaminophen given alone or in drug combinations), dextropropoxyphene, tranquilizers, antidepressants, and (undisclosed) use of herbal medicines.

Liver Disease Associated with Particular Classes of Drugs Antimicrobial Agents Penicillins Hepatic injury associated with natural penicillins (e.g., penicillin G, penicillin V) is poorly documented (14). It is usually recorded in the setting of anaphylaxis, suggesting a possible ischemic basis for liver injury rather than direct toxicity (113). In contrast, the semisynthetic penicillins have been implicated in many hepatic drug reactions, including hepatocellular injury, bland cholestasis, and cholestatic hepatitis that may lead to VBDS (114,115,116) (Table 33.18).

Oxacillin There are many reports of abnormal liver test results, mainly raised AT levels (117,118), with oxacillin. Isolated instances of cholestatic hepatitis or acute hepatitis have also been reported. Onset is within 2 to 24 days. Although eosinophilia has been described, features of hypersensitivity are not conspicuous. The liver test abnormalities usually normalize when the drug is withdrawn.

Flucloxacillin Over 600 cases of cholestatic hepatitis have been reported, mainly from Europe, Scandinavia, and Australia (119,120,121,122,123). The frequency of liver injury is between 1 and 10 cases per 100,000 persons exposed (120,122). Risk factors for flucloxacillin-induced liver injury are high daily doses, prolonged courses (>2 weeks), and age over 55 years (120). Symptoms usually begin after 1 to 9 weeks but can be delayed for up to 6 weeks after the antibiotic course is completed. Nausea, anorexia, and vomiting herald the onset of hepatitis P.944 and are followed by jaundice and pruritus. Constitutional symptoms and weight loss are often striking. Blood tests reflect severe hepatitis with high AT, SAP, and GGTP values. Bilirubin levels can be markedly raised (122). Liver histology shows cholestatic hepatitis with bile duct injury and ductopenia (121). This is a very severe form of drug-induced liver disease, and the reported mortality is up to 5% (20). Although most patients recover after drug withdrawal, prolonged cholestasis is observed in 10% to 30%, and in some cases this can lead to cirrhosis. Management is supportive in the acute phases, but with continued cholestasis ursodeoxycholic acid appears to benefit approximately two thirds of cases (69). The postulation of an idiosyncratic basis for flucloxacillin liver toxicity is supported by the identification of reactive metabolites capable of inducing cytotoxicity in biliary epithelial cells (124).

Table 33.18. Hepatic Injury Associated with Antimicrobial Agents

Drug

Pattern of liver injury

Comments

Penicillin G

Acute hepatitis, granulomatous

Very rare; hypersensitivity features often

Penicillin V

hepatitis

present

Ampicillin

Acute hepatitis, mixed

Rarely, vanishing bile duct syndrome;

hepatocellular–cholestatic injury,

cross-hepatotoxicity with cefuroxime

granulomatous hepatitis

Ampicillin– sulbactam

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Single case

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Amoxicillin,

Minor, nonspecific increase in

carbenicillin

aminotransferases

Amoxicillin–

Cholestatic hepatitis with bile

Associated with vanishing bile duct

clavulanate

duct injury; acute hepatitis (15%

syndrome; granuloma; cirrhosis (single

of cases)

case)

Cholestasis with bile duct injury;

Similar toxicity with oxacillin, cloxacillin,

vanishing bile duct syndrome

and dicloxacillin, but possibly less

Flucloxacillin

—

frequent, less severe

Cephalosporins

Minor liver injury, acute

Rare; mild, reversible; granulomas

hepatitis, cholestatic hepatitis

(cephalexin); biliary sludge (ceftriaxone)

Chloramphenicol

Hepatocellular, cholestasis

Hepatic injury rare

Cotrimoxazole

Acute hepatitis, cholestatic

Cholestasis recorded with trimethoprim

hepatitis, granulomatous

alone; increased risk with human

hepatitis, vanishing bile duct

immunodeficiency virus/acquired

syndrome

immunodeficiency syndrome


Also with azithromycin, clarithromycin,

Erythromycin

roxithromycin

Minocycline

Acute and chronic hepatitis

Autoimmune hepatitis–type features (see text)

Nitrofurantoin

Acute and chronic hepatitis,

Declining incidence; was common in long-

granulomatous hepatitis,

term users (>6 m)

cirrhosis

Quinolones

Mainly cholestasis; rarely

Overall low incidence; granulomas

hepatitis, fulminant hepatic

(norfloxacin)

failure;

Sulfonamides

Acute hepatitis, cholestatic

Similar toxicity with sulfones,

hepatitis, granulomatous

sulfasalazine, pyrimethamine–sulfadoxine

hepatitis, vanishing bile duct syndrome

Tetracycline

Microvesicular steatosis

Rarely, vanishing bile duct syndrome

Trovafloxacin

Fulminant hepatic failure

Now withdrawn

Cloxacillin and dicloxacillin Some data indicate that cholestatic hepatitis may be less common and possibly less severe with cloxacillin and dicloxacillin, compared with flucloxacillin (123), but this remains unproved and controversial. In other respects, the liver injury and clinical course resemble the flucloxacillin reaction described earlier (122).

Amoxicillin–clavulanate (Augmentin) At least 150 cases of cholestatic liver injury have been attributed to amoxicillin–clavulanate (34,35,125,126). The clavulanate component has been implicated because such toxicity is rare with amoxicillin, whereas other clavulanate–penicillin compounds such as ticarcillin–clavulanate (Timentin) can cause cholestasis (127,128). The frequency of liver injury has been estimated at 1.1 to 2.7 cases per 100,000 persons exposed (22). Male gender, age over 60 years, and prolonged courses of treatment are risk factors for hepatic injury. Although there is a strong association with DRB1 *1501-DRB5*0101-DQB1*062 (34,35), this haplotype does not appear to influence the clinical expression and outcomes of amoxicillin–clavulanate hepatitis.

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Onset is within 6 weeks (mean 18 days) of beginning therapy; rarely, the onset of symptoms may be up to 8 weeks after completion of treatment (129). Hypersensitivity features such as fever, rash, and eosinophilia are seen in 30% to 60% of patients (113). Bland cholestasis or cholestatic hepatitis is observed in biopsied cases (125). Bile duct injury and perivenular bilirubinostasis with ceroid pigment deposits are often present. Other histologic features include hepatic granulomas, biliary ductopenia (34,129,130,131,132), and rarely, cirrhosis (133). Most patients recover but this can take up to 4 months. Fatalities are rare (134).

Quinolones Transient increases in AT levels are recorded in 2% to 3% of fluoroquinolone recipients. Serious liver injury is infrequent, with the exception of trovafloxacin, which was withdrawn because of severe hepatotoxicity (135). Among the reported cases, cholestatic liver injury predominates, usually occurring within 2 to 21 days (82,136,137,138). Ciprofloxacin (137), norfloxacin (138), ofloxacin (139), gatifloxacin (140), and moxifloxacin (141) have all been implicated. Instances of hepatocellular injury have also been recorded, including acute liver failure with ciprofloxacin (82,142) and ofloxacin (139). Acute cholestatic hepatitis followed by prolonged cholestasis and biliary ductopenia were observed with gatifloxacin (140). Two elderly subjects with renal impairment developed acute hepatocellular injury with levofloxacin, presumably a consequence of altered pharmacokinetics because levofloxacin undergoes renal elimination (143).

Tetracycline Tetracycline hepatotoxicity was characterized by microvesicular steatosis, resulting in acute liver failure. Risk factors included the administration of high intravenous dosages (usually >2 g/day) of tetracycline to women during pregnancy (15,144) or to men while taking estrogens. The other important risk factor was renal failure, which reduces tetracycline clearance. The clinical features resembled those now seen in some cases of severe liver injury associated with HAART (see later section). Tetracycline hepatotoxicity is attributed to impaired hepatic lipid transport and inhibition of mitochondrial β-oxidation of fatty acids (2). It is no longer observed, now that tetracycline is contraindicated in pregnancy. Oral tetracycline has been associated with two cases of prolonged cholestasis with bile duct injury; bilirubin levels remained elevated for approximately 3 years in one of these patients (90).

Minocycline Minocycline, a semisynthetic tetracycline used in treating acne, is an important cause of drug-induced liver disease (145,146,147). A systematic review identified 65 published cases, while 493 (6%) of the over 8,000 adverse drug reactions attributed to minocycline reported to an international pharmacovigilance center were liver related (148). Two modes of presentation are described. Those presenting with “early onset” hepatitis (within 5 weeks) exhibit prominent hypersensitivity features such as exfoliative dermatitis, lymphadenopathy, and eosinophilia; this is typical of the RMS (Table 33.5). Among such cases, 6 of 16 were in patients of African Caribbean ethnicity, suggesting possible racial susceptibility. By contrast, long-term minocycline P.945 recipients (>12 months) present with a clinical and histologic picture simulating AIH, with fever, arthralgia (>70%), antinuclear antibodies (ANAs) and/or SMAs (>90%), and raised level of globulins (149). Other features of drug-induced SLE may be present, including arthritis and nephritis (145). The absence of tissue eosinophilia in some cases may divert attention from a drug etiology. Approximately half (48%) of those affected have been women, most (94%) younger than 40 years. This reflects, in part, the age of those exposed to prolonged minocycline for the treatment of acne. Most patients recover completely after minocycline is discontinued. However, both acute and chronic hepatitis can be severe, with a few patients needing liver transplantation or dying from liver failure (150,151). Occasionally, patients seemed to benefit from a short course of immunosuppressive therapy, but it is unclear whether spontaneous resolution would have occurred. Among fatal cases, additional factors such as myocarditis or concurrent viral infections may have contributed to the mortality (148). It is unclear how minocycline induces AIH. The sera of one affected patient contained antibodies that reacted with 50- and 90-kDa proteins expressed by human HCC cell lines and with rat CYP proteins (152); this raises the possibility of molecular mimicry between drug-induced autoantibodies and host proteins. The suggestion that minocycline could have triggered latent AIH seems less plausible because most affected patients recover without immunosuppression, and hepatitis occurs in those who do not exhibit the usual HLA haplotypes (HLADR3 and HLA-DR4) associated with AIH (153).

Sulfonamides Sulfonamides have long been implicated as causing acute and chronic hepatitis; cholestatic, granulomatous, or mixed reactions; and rarely fulminant hepatic failure (113,154,155). Persons with HIV/AIDS (156) are particularly susceptible, implicating immune dysregulation in the pathogenesis of the hepatic injury. On the other hand, 90% of patients with sulfonamide hypersensitivity in one series were identified as slow acetylators (157,158); reduced activity of the acetylation pathway may contribute to defective detoxification of a sulfonamide metabolite or facilitate the CYP-mediated production of a nitroso metabolite (14,159). How this triggers an apparent immune liver injury is unclear. Sulfonamide-induced liver injury usually occurs in the setting of systemic drug hypersensitivity (Table 33.5). Symptoms begin early (within 2 weeks of starting therapy). Associated features include a rash (occasionally

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with the Stevens-Johnson syndrome), vasculitis, lymphadenopathy, pancreatitis, neuropathy (113), pancytopenia, and renal failure (158).

Sulfonamide combinations: Cotrimoxazole, sulfasalazine, sulfadoxine, and pyrimethamine (Fansidar) In addition to other types of sulfonamide-induced liver injury, prolonged cholestasis with biliary ductopenia has been attributed to cotrimoxazole (160,161). Significant liver injury has occurred in recipients of sulfasalazine (see subsequent text) and pyrimethamine–sulfadoxine (Fansidar) (162).

Sulfasalazine and mesalamine Sulfasalazine has been associated with several reports of acute hepatitis (163,164,165,166,167). Sulfasalazine-associated hepatic injury was observed more often in patients with rheumatoid arthritis than in those with inflammatory bowel disease (168). Reactions are often severe, and at least ten deaths have been recorded. Fever, rash, and arthralgia usually develop within 1 to 4 weeks. Liver injury was originally ascribed to the sulfonamide component (sulfapyridine). However, other 5-aminosalicylic acid (5-ASA) compounds, including mesalamine (mesalazine) and olsalazine, can also cause acute hepatitis, implicating the 5-ASA moiety in at least some cases (169,170). Sulfasalazine- and mesalamine-related hepatic drug reactions occur with similar frequency (168). Mesalazine has also been associated with cholestasis (170a) and rarely chronic hepatitis (one report) with hypergammaglobulinemia, ANAs, and SMAs (169).

Dapsone (4,4-diaminodiphenylsulfone) Indications for dapsone include leprosy, dermatitis herpetiformis, and increasingly, treatment of Pneumocystis carinii infection in HIV-positive individuals. Liver involvement as part of a severe hypersensitivity syndrome (“sulfone syndrome”) is well described with dapsone. This reaction, another example of the RMS (see preceding text), is reported in up to 1.3% of dapsone recipients (171). Most cases occurred within 6 weeks. Liver histology shows acute hepatitis or cholestatic hepatitis. Hepatic granulomas or acute cholangitis are also described (172). Resolution occurs within 4 weeks of stopping dapsone. Acute liver failure and death are uncommon but can occur in severe cases. Corticosteroids have been used with success in some reports. However, untreated patients have also recovered, while fatalities are recorded despite corticosteroid use (171,172).

Nitrofurantoin Cases of significant hepatotoxicity still occur with this formerly prescribed urinary tract antiseptic; in a recent survey from Michigan, nitrofurantoin accounted for 3 of 32 (10%) cases of drug-induced hepatitis (173). P.946 Acute and chronic hepatitis are the most characteristic hepatic syndromes, but varying degrees of cholestasis can occur, as do granulomas in rare cases. Nitrofurantoin-induced chronic hepatitis simulates AIH. It is seen only in individuals using nitrofurantoin for more than 6 months; in some cases, exposure is intermittent and to very small doses of nitrofurantoin, such as those found in cow's milk (174). Positive rechallenge is well documented and may occur even after 17 years (175). The clinical features are those of chronic hepatitis with fatigue, malaise, nausea, abnormal liver test results with raised level of ALT, hypoalbuminemia, and hyperglobulinemia. ANAs (80%) and SMAs (70%) are often present. Cirrhosis is present in up to 20% of patients with nitrofurantoin-induced chronic hepatitis. Nitrofurantoin is also an important cause of pulmonary fibrosis, and concurrent liver and lung injury are observed in approximately 20% of persons developing nitrofurantoin hepatitis (176). Clinical recovery follows nitrofurantoin withdrawal, but the course may be prolonged and sometimes recovery is incomplete (2). Corticosteroids are not routinely used but patients taking these medications seem to have accelerated recovery in occasional cases (177). Monitoring liver tests is not likely to be clinically useful or cost-effective.

Erythromycins and other macrolide antibiotics Erythromycin estolate was recognized as a paradigm of cholestatic hepatitis in the early 1970s, but similar toxicity, although far less common, has been reported with all the erythromycin esters (rarely with erythromycin base) and other macrolides, such as clarithromycin (14). The presence of fever, serum, and tissue eosinophilia, along with the accelerated response to rechallenge, is consistent with immunoallergic idiosyncrasy, although intrinsic toxicity may also contribute (178). Symptoms begin 2 to 25 days after commencing treatment (114). Nausea, anorexia, vomiting, and abdominal pain are common; the abdominal pain may be quite severe and it mimics acute cholecystitis. Before this syndrome was appreciated, inappropriate cholecystectomy was often performed. Dark urine (bilirubinuria), jaundice, and itch may also occur. The biochemical profile shows raised AT and alkaline phosphatase levels, with hyperbilirubinemia in severe cases. Peripheral eosinophilia can occur. Liver biopsies show intrahepatic cholestasis and portal inflammation, often accompanied by numerous eosinophils. Rare cases have been associated with chronic cholestasis, with biliary ductopenia on histologic sections. Most recover after the drug is withdrawn, although liver test abnormalities may take up to 4 months to subside (87). Cross-sensitivity between erythromycin preparations has been reported (113). Intravenous

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erythromycin lactobionate (179) has been implicated in a case of fulminant hepatitis. Clarithromycin (180,181), azithromycin (182,183), and roxithromycin (184) have also been associated with cholestasis or mixed hepatocellular–cholestatic injury. Two reports of fulminant hepatic failure have accrued for clarithromycin; one of these patients was also receiving disulfiram (see “Disulfiram”) (185,186).

Antituberculous Drugs Of the current antituberculous drugs, hepatotoxicity is an important complication of INH, rifampin, and pyrazinamide, particularly when used in combination. Risk factors for liver injury are shown in Table 33.19. Except for a single report of cholestasis (187), ethambutol appears to be devoid of hepatic adverse effects. Among drugs used in the past, severe hepatocellular injury and cholestasis were recorded with paminosalicylic acid, often as part of a multisystem syndrome with hypersensitivity features (2); prothionamide (hepatocellular injury); and ethionamide (2). Ethionamide is still used rarely as a second-line antituberculous drug. Rifabutin causes liver enzyme changes, but these are usually part of hepatic adaptation; hepatitis has not been a problem.

Isoniazid Frequency and risk factors The hepatotoxic potential of INH was established by landmark studies in the late 1960s and early 1970s (188,189,190,191). Minor (less than threefold) elevations in the level of serum AT occur in 10% to 20% of subjects during the first 3 months of treatment. However, these AT abnormalities often settle with continued treatment and a progressive rise is uncommon. Jaundice occurs in approximately 1% of recipients of INH but in more than 2% of those aged 50 years or older. Conversely, liver injury is rare in persons younger than 20. Women, especially of African American and Hispanic ethnicity, and P.947 persons with a history of excessive alcohol use are also at increased risk of toxicity (190,192). The presence of hepatitis B, hepatitis C, or HIV has been suggested as a risk factor (54,193). The relative risk of developing hepatotoxicity if the person was hepatitis C or HIV positive was 5-fold and 4-fold, respectively, and 14-fold in case of HIV/HCV coinfection. Antituberculous therapy could be reinstituted after successful antiviral therapy against HCV. In another study, persons who were hepatitis B surface antigen (HBsAg) positive were more likely to sustain liver injury than HBsAg-negative individuals (9). Further, those with positive replication status (i.e., HBeAg positive) had a higher likelihood of developing hepatotoxicity with INH than those with “inactive” hepatitis B (7.7-fold increased risk). Discontinuation rates were also higher in the former group. Opposing views were expressed in a case–control study (194) in which malnutrition was the only determinant of hepatotoxicity.

Table 33.19. Risk Factors for Antituberculosis Treatment–Related Hepatotoxicity

Age over 60 y Serum albumin 3 mg/dL or AT × 10 times ULN or baseline values) between a cohort with and without

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baseline elevation of liver test results (0.6%, 0.2%, respectively) (333). Lovastatin (334), pravastatin (335), atorvastatin (336), and simvastatin (337) have been implicated in a few cases of cholestatic hepatitis. Acute liver failure has also been attributed to lovastatin. This is an extremely rare event (10 years) is increased 100-fold. Patients with liver adenomas usually present with a painless or tender right upper quadrant mass or occasionally with hemoperitoneum secondary to hepatic rupture. Adenomas usually regress after OCSs are withdrawn (101), but surgery is required for larger lesions to avert possible rupture (353) or because of the small but definite risk of malignant transformation. To prevent hepatic adenomas, OCSs with lower estrogenic potency are preferred. Long uninterrupted periods of OCS use should be avoided.

Hepatocellular carcinoma The relative risk for HCC is increased twofold among women who have ever taken OCS, and it is increased sevenfold in long-term users (>8 years) compared with age-matched controls (26,353,354). However, it must be emphasized that estrogen-related HCC is rare, accounting for less than 2% of primary liver cancer in western countries. In countries with a high prevalence of HCC, OCS is not an independent risk factor because of the far greater importance of chronic viral hepatitis and aflatoxin (26). Median age at presentation is 30 years, and HCC occurs at least 5 years after starting combination OCSs. The tumors are well differentiated and have a better short-term outcome than HCC because of other causes (14).

Anabolic steroids Cholestasis At high doses, anabolic steroids often produce reversible bland cholestasis, usually within 1 to 6 months of beginning treatment. Prolonged jaundice with ductopenia is a rare complication (355). Acute hepatitis is also an unusual sequel after self-ingestion of high-dose anabolic steroids (356).

Benign neoplasms The association with hepatic adenomas is less robust. Many reports were from patients with Fanconi's anemia (357), a disorder caused by genomic instability and a resultant high background incidence of neoplasms. However, reports of adenomas among female body builders and in persons taking anabolic steroids for other indications (354,358) indicate a probable etiologic association. Oral and parenteral androgens are both implicated (354). Hepatic adenomas were identified in 3 of 11 long-term users of danazol (359), all patients with hereditary angioneurotic edema. Danazol-associated hepatic adenomas have also been observed in other disorders such as SLE and endometriosis. For this reason, surveillance ultrasonography is suggested in long-term recipients of danazol (359) and also for former users of other anabolic steroids; liver tumors have been described up to 24 years after steroid discontinuation (354). These tumors can regress with androgen withdrawal (360), but this is not always the case and surgical resection may be required.

Hepatocellular carcinoma Several cases of HCC have been documented (361,362), but confounding P.956 factors such as viral hepatitis were not clearly excluded in earlier cases. Because some of these tumors metastasize late and sometimes regress (363), doubts have been expressed about the true nature of these tumors; it is sometimes difficult to distinguish well-differentiated HCC from adenomas (364). Furthermore, hepatic adenoma and HCC can coexist (365). Four reports of HCC have been attributed to long-term danazol use (366,367); the underlying diseases were hereditary angioneurotic edema, SLE, and chronic idiopathic thrombocytopenic purpura. These liver tumors were large, well-differentiated carcinomas that did not show regression with drug withdrawal. Serum α-fetoprotein levels were normal in three of the four cases; therefore, α-fetoprotein cannot be used as the sole tumor marker for diagnosis in these patients.

Estrogen-receptor antagonists The range of tamoxifen hepatotoxicity includes hepatic steatosis, NASH, and rare instances of submassive hepatic necrosis and even cirrhosis. Of these, the association with hepatic steatosis and NASH is most striking. In one series of 66 women with breast cancer who had received tamoxifen for 3 to 5 years, 24 showed radiologic evidence of hepatic steatosis (368). In another study, liver biopsy specimens were obtained from 15

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women with moderate-to-severe hepatic steatosis (as designated by liver/spleen CT scan ratio of 3 × ULN), the drug should be discontinued. As with INH, symptoms suggestive of hepatitis should be assessed immediately. Individuals who developed jaundice with troglitazone should not receive these thiazolidinediones, although cross-toxicity was not a problem in one reported case (420). It must be noted that however intuitive such biochemical screening may seem, this protocol has not been validated. Even if adhered to strictly, it could not have prevented some cases of fatal hepatotoxicity in which transition from normal AT to liver failure occurred within 1 or 2 weeks (411). In this situation, the probability of detecting new cases by monthly monitoring is extremely low (estimated at 0.000065) (424). Further, the troglitazone episode has highlighted the low compliance with monitoring recommendations; less than 5% of patients taking troglitazone were monitored per protocol. Finally, the positive predictive value of abnormal liver tests is likely to be suboptimal in patients with type 2 diabetes (425) because of confounding factors such as nonalcoholic fatty liver disease (NAFLD)/NASH (see Chapter 39), chronic hepatitis C, or concomitant drug therapy.

Oral hypoglycemic drugs Liver injury (typically hepatocellular) was common with older sulfonylureas, such as carbutamide, metahexamide, and chlorpropamide (2,14). Of the currently used agents, tolbutamide, tolazamide, glibenclamide, and glimepiride have rarely been associated with cholestasis or cholestatic hepatitis (2,426,427,428). Considering the structural relationship of sulfonylureas with sulfonamides, it is perhaps not surprising that hypersensitivity phenomena (fever, skin rash, eosinophilia) were present in some (but not all) cases (429). Most cases resolved after drug withdrawal, but chronic cholestasis progressing to VBDS has been described with tolbutamide and tolazamide (14). Death from liver failure has been reported in two patients, one of whom had cirrhosis (429). There are three reports of acute hepatitis induced by gliclazide; hypersensitivity features were present in one case (429a). Glibenclamide has also been P.960 associated with hepatocellular liver injury and hepatic granulomas (426).

Table 33.22. Liver Injury Associated with Drugs Used in Diabetes Mellitus

Drug


Acarbose

Acute hepatitis; most reported cases from Spain

(glucosidase

(to date)

inhibitor)

Cholestasis with voglibose (another glucosidase

Comments Positive rechallenge

inhibitor)

Metformin

Cholestatic hepatitis; cholestasis; acute hepatitis

Very rare

Mixed liver injury; all reports from Japan;

Positive rechallenge

(biguanide)

Human insulin

resolved when changed to porcine insulin

Sulfonylureas

Acute hepatitis, cholestasis, cholestatic hepatitis,

Usually reversible but

vanishing bile duct syndrome, granulomatous

fatalities reported

hepatitis

Repaglinide

Acute hepatocellular injury

Single report

Submassive or massive hepatic necrosis;

Many fatal cases.

cholestasis

Withdrawn from use

Acute cholestatic hepatitis, granulomatous

Few reports, fatalities

hepatitis

rare

Acute hepatocellular injury; cholestatic hepatitis

Few reports, fatalities

(one case), fulminant hepatic failure (one case)

rare

Thiazolidinediones

Troglitazone

Rosiglitazone

Pioglitazone

Other antidiabetic agents that have been rarely associated with liver injury include metformin, repaglinide,

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acarbose, and human insulin (430,431,432,433) (Table 33.22).

Analgesics and Drugs Used to Treat Rheumatologic Diseases Acetaminophen Acetaminophen (paracetamol) hepatotoxicity is an important cause of drug-induced liver injury in most countries (434,435); currently it accounts for approximately 50% of cases of acute liver failure in the United States (436). When used in recommended doses (1 to 4 g/day), acetaminophen is extremely safe (437), but single doses exceeding 15 to 25 g may cause severe liver injury that is fatal in up to a quarter of cases. Acetaminophen hepatotoxicity usually follows deliberate self-poisoning in an attempted suicidal or parasuicidal gesture. However, up to 30% of cases of acetaminophen hepatotoxicity admitted to hospital now result from “therapeutic misadventure,” in which the daily dose has not greatly exceeded the recommended safe limits but in which specific risk factors were present (438,439) (see subsequent text); daily doses of 2 to 6 g have been associated with fatal hepatotoxicity. Cases associated with actual therapeutic doses are much rarer and may represent inadequate/unreliable disclosure and documentation.

Risk factors Acetaminophen causes dose-dependent liver injury but individual susceptibility is also important. Therefore, death has occurred after ingestion of single doses of 7.5 g in adults or 150 mg/kg in children, whereas survival has been recorded with massive overdoses (50 g or more) (440). Age alters individual susceptibility; liver injury has been described even in neonates, but children are considered to be relatively resistant to acetaminophen poisoning (441). This has been attributed to differences in disposition and metabolism of the drug, but relatively larger liver and kidney sizes (as a proportion of total body weight) is an alternative explanation (442). However, there is increasing recognition that both intentional and unintentional acetaminophen toxicity can occur in children. Common prescribing errors involved in these cases include use of adult doses, wrong dosing intervals, concomitant use of other acetaminophen-containing or hepatotoxic products, and host factors—particularly undernutrition, fasting, and drug–drug interactions. Rectal preparations of acetaminophen were implicated in a few cases. The bioavailability of acetaminophen in this formulation can vary (up to ninefold). Furthermore, the slower onset of action encourages repetitive use and consequent cumulative toxicity (443). Although acetaminophen self-poisoning is more common in women, fatal acetaminophen hepatotoxicity occurs more frequently in men; this is largely due to alcoholism and late presentation (20).

Clinical features The clinical evolution of liver injury follows three phases. In the first, anorexia, nausea, and vomiting are prominent, and this may last from 12 to 24 hours. These symptoms often subside so that the person often feels well during the second phase, which lasts another 24 hours. Signs of hepatic failure, often with renal insufficiency, appear 48 to 72 hours after ingestion of acetaminophen (phase 3). Pain over the liver may be pronounced. It is accompanied by jaundice, hypoglycemia, coagulopathy, renal failure, acidosis, and encephalopathy. Myocardial injury has also been described (440). Renal failure can occur with or without significant liver injury. In untreated subjects, death P.961 occurs between 4 and 18 days after drug ingestion, usually from cerebral edema, and/or sepsis from multiorgan failure. ALT levels are markedly elevated (2,000 to 10,000 IU/L); indeed, when the cause of acute liver injury is unclear (e.g., in an unconscious individual or someone known to have chronic hepatitis C), such high AT levels should arouse suspicion of acetaminophen toxicity. These high ALT values are unusual in viral hepatitis but may occur with ischemic hepatitis and with other forms of drug-induced liver injury, including herbal toxicity (see later section). The following clinical and laboratory indices predicate a poor outcome of acetaminophen hepatotoxicity: Prothrombin time greater than 100 seconds, serum creatinine greater than 300 µmol/L, the single finding of a pH of less than 7.3 after adequate fluid replacement, or grade 3 or 4 encephalopathy in patients with a normal pH (434,444). Other prognostic indices proposed include the Acute Physiology and Chronic Health Evaluation (APACHE) II score, and blood lactate, phosphate, and α-fetoprotein levels (445). None of these indices has been widely adopted, and they await independent validation.

Histology The histologic features are zone 3 necrosis, with submassive (bridging) or panacinar (massive) necrosis in severe cases (14). Inflammatory activity is inconspicuous, and resolution occurs without fibrosis. Chronic liver injury has been described in patients consuming moderate doses of acetaminophen for many months (2 to 6 g each day). Preexisting liver disease or concurrent alcohol intake were not always excluded in such individuals (14), and the rapid resolution after discontinuing acetaminophen abuse implies a form of chronic hepatotoxicity rather than a syndrome of drug-induced chronic hepatitis.

Acetaminophen toxicity with therapeutic doses (therapeutic misadventure) Enhanced susceptibility to acetaminophen toxicity is now well recognized both in alcoholic and nonalcoholic individuals. At least 200 instances of inadvertent hepatotoxicity have been recorded in heavy drinkers; they

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have followed acetaminophen intake for 1 day to several weeks. In one series, 40% of individuals had taken acetaminophen in excess of 6 g/day (438), but 35% had taken doses below 4 g/day; in other reports, hepatotoxicity has occurred after as little as 1.5 to 2 g of acetaminophen intake a day. Data from the US Acute Liver Failure group revealed that 60% of persons who had taken an unintentional overdose were using an acetaminophen–narcotic combination. It has been suggested that addiction (and later, tolerance) to the narcotic component induces repetitive use that may not always be recalled or disclosed by the patient (436). Alcohol enhances CYP 2E1 activity, and accompanying malnutrition may contribute to GSH depletion. As in acute self-poisoning cases, AST and ALT levels are often 40- to 1,000-fold elevated above the ULN; this allows ready distinction of cases of acetaminophen hepatotoxicity from alcoholic hepatitis. The importance of chronic excessive alcohol intake as a potentiator for susceptibility to acetaminophen hepatotoxicity has recently been challenged because in many case reports invoking such an interaction the person had clearly taken a hepatotoxic dose of acetaminophen (412). Nonetheless, the authors’ experience is that therapeutic misadventures with acetaminophen are a common and clinically important type of druginduced liver injury (434,446). A recent study of alcohol–acetaminophen interaction was conducted in an alcohol detoxification unit, with all trial participants receiving acetaminophen 1 g q.i.d. for 2 days or placebo (447). No differences in hepatotoxicity were observed between the two groups. However, the investigators’ assertion that acetaminophen can be safely used in patients with chronic alcohol abuse has been criticized on several grounds, including the selection of only those persons with serum AT levels less than 120 U/L, which could have excluded a subset with significant underlying liver disease (448). The FDA recommends that persons taking more than three drinks of alcohol daily should not receive acetaminophen. In nonalcoholic patients, fasting (449) has emerged as one of the most important risk factors, particularly after near complete deprivation of carbohydrate intake for at least 48 hours; this is a particularly important risk factor for acetaminophen hepatotoxicity in young children. Fasting decreases the activity of hepatic conjugation pathways for acetaminophen elimination, increases CYP 2E1 activity, and depletes hepatic GSH levels. However, others have contended that fasting has been overstated as a risk factor for acetaminophen hepatotoxicity (450). They contend that earlier studies were flawed because CYP 2E1 and GSH measurements had not been carried out simultaneously; depletion of GSH level is also accompanied by a decrease in CYP 2E1 activity (450). Concurrent medication (e.g., INH, zidovudine, phenytoin, and other anticonvulsants) are also important. These agents compete for the “safe” conjugation pathways and may also induce CYP 3A4 (phenytoin) or 2E1 (INH), the net effect of which is to promote CYP-mediated oxidation of acetaminophen to its reactive intermediate, Nacetyl-p-quinone imine (NAPQI). However, human studies do not appear to support a phenytoin– acetaminophen adverse interaction. It is contended that phenytoin induces only CYP 3A4, a relatively minor metabolic pathway; further, it enhances P.962 glucuronidation, a key detoxification step (450). Severe cardiopulmonary disease and renal failure have also been described as settings for acetaminophen hepatotoxicity (451), although the importance of metabolic factors or impaired (fluctuating) hepatic blood flow was not clarified in these studies.

Mechanism of liver injury and basis for antidote therapy Acetaminophen undergoes metabolism to glucuronide and sulfate conjugates, which are excreted in the urine. Normally, only a small proportion (approximately 5%) of acetaminophen is oxidized to NAPQI; this reaction is catalyzed by CYP 2E1 (which increases with fasting, and INH and chronic alcohol intake) and, to a lesser extent, by CYP 3A4 (induced by anticonvulsants, several other drugs, and possibly alcohol). The small amounts of NAPQI formed with pharmacologic doses of acetaminophen are readily detoxified by hepatic GSH; hepatorenal injury occurs only when GSH reserves are depleted. This is the basis for the therapeutic rationale of administering thiol donors such as NAC and methionine, which replenish intracellular GSH stores (440). NAPQI binds cellular proteins, inducing oxidation of thiol groups in mitochondria, leading to mitochondrial permeability transition (452). The ensuing mitochondrial dysfunction generates profound oxidative stress and also facilitates peroxynitrate formation; the latter can also undergo covalent binding with key proteins and also further aggravate mitochondrial dysfunction. These events culminate in oncotic necrosis (oncosis) of hepatocytes and sinusoidal endothelial cells. Although apoptosis does occur, oncosis is considered the principal mode of cell death (453). Depletion of natural killer (NK) cells and NK cell with T-cell (NKT cell) receptors appears to protect against acetaminophen liver toxicity in mice (454). The reduction in liver injury was accompanied by decreased expression of proinflammatory cytokines such as interferon-γ, key chemokines, and neutrophil recruitment. On this basis, it has been suggested that these cells, which are part of the hepatic innate immune system, may contribute to the progression of acetaminophen-induced liver injury (454).

Prevention Adherence to the recommended therapeutic dose should be stressed. However, both prescribers and consumers should be made aware of the increased risk of acetaminophen toxicity in those who consume excess alcohol and in the setting of prolonged fasting, cardiorespiratory disease, and where other drugs are also being used. Recently, doubts have been expressed about the safety of acetaminophen in patients with underlying liver disease. Although acetaminophen is not contraindicated in such persons, the finding of detectable serum levels of acetaminophen in 20% of those with acute viral hepatitis–related acute liver failure has raised questions on the safety of acetaminophen in both acute and chronic liver disease (455). There is a

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public health need to revise downward and promulgate altered dosage guidelines for acetaminophen when used in regular daily doses under any of the high-risk circumstances mentioned earlier. To reduce the impact of impulsive self-poisoning, attempts have been made to restrict pack sizes and change the packing (to bubble packs) of acetaminophen by legislation in the United Kingdom. This has been associated with a reduced number of liver transplantations for acetaminophen overdose (by approximately 66%), as well as a reduction in mortality (by 21%) (455). However, the impact has not been uniform, with only a transient decline in Scotland, and it remains unclear whether the decline in adverse outcomes is attributable to this measure alone (456).

Management Gastric lavage with a wide-bore tube is performed in all patients presenting within 4 hours of acetaminophen overdose. Activated charcoal and osmotic cathartics are of no benefit. Serum levels of acetaminophen are often determined at baseline, but a 4-hour postingestion level is a more reliable predictor of the risk of liver injury (457). The need for antidote treatment is assessed using blood acetaminophen levels with reference to well-established nomograms (458,459). The 4-hour serum acetaminophen concentration may be misleading in overdoses with extended-release acetaminophen preparations (460); blood acetaminophen levels should be estimated after a further 4 to 6 hours (460). In persons presenting after nonaccidental or staggered ingestion of acetaminophen, the total dose ingested and time from ingestion to presentation are important determinants of liver injury. In these cases, hepatotoxicity is likely if the interval exceeds 24 hours or if the total acetaminophen dose exceeds 150 mg/kg (75 mg/kg in high-risk individuals); NAC therapy is initiated beyond these thresholds (461). NAC is the principal antidote. By functioning as a thiol donor, NAC replenishes intracellular GSH stores. Significant hepatotoxicity is rare when NAC is administered within 16 hours of drug ingestion. Beyond 16 hours, oxidation of acetaminophen to NAPQI is complete and thiol donation is unlikely to prevent hepatocyte or renal tubular cell death. Nevertheless, the benefits of NAC have been shown extend to patients presenting up to 24 hours and even in those with acute liver failure (462). The beneficial effects of NAC in acute liver failure were attributed to improved tissue P.963 oxygen delivery (462), although this has been disputed (463). NAC is administered intravenously in Europe and Australia, and by mouth in the United States (459,464). The intravenous regime is now approved by the FDA for persons who cannot or will not use oral NAC.

Treatment protocol An oral loading dose of 140 mg/kg is followed by 4-hour administration of half this dose up to 72 hours. Intravenous administration involves a loading dose (150 mg/kg) of NAC given slowly over 15 minutes, followed by a 4-hour infusion (50 mg/kg) and a 100-mg/kg infusion over 16 hours. A third intravenous (48-hour) protocol has also been evaluated (465). It has been suggested that the incidence of hepatotoxicity is lower with the oral and 48-hour intravenous regimes when compared to the 20-hour intravenous infusion among high-risk patients (460), but direct comparisons have not been performed. Only the 20-hour intravenous protocol has been approved by the FDA. Anaphylactoid reactions to intravenous NAC are relatively common (6% to 15%). They are generally mild and rarely lead to treatment discontinuation, but severe reactions can occur. Guidelines to deal with such reactions (466) include observation during drug administration (with appropriate antidotes readily available), discontinuing the infusion with the onset of angioedema or respiratory symptoms, administration of antihistaminics, and resumption of the infusion after 1 hour if there are no persistent symptoms. For minor reactions, such as flushing, the infusion can be slowed or continued uninterrupted (466). Other thiol donors such as methionine may be effective but must be administered within 10 hours. Methionine solutions should be freshly prepared, else they often cause troublesome vomiting; their use is restricted to patients with hypersensitivity to NAC. Managing acetaminophen overdoses in pregnant women and in children is along usual lines (460); in one small study, NAC did not have any major adverse effects on the fetus (467). Treatment of acute liver failure is along usual lines (see Chapter 21). Assessment for liver transplantation requires consideration of the psychosocial factors underlying self-poisoning and the likelihood of survival without transplantation. When liver transplantation has been performed, survival rates exceed 70% (434) and long-term outcomes appear reasonable. However, deaths have occurred in survivors from repeat overdoses, stressing the need for detailed psychiatric evaluation and support before and after transplantation (468).

Dextropropoxyphene Dextropropoxyphene is an opioid that is commonly used in compound analgesics, as well as on its own. Adverse drug reactions are rare but important, particularly because liver injury may occur in the postoperative period or in other medically complex situations. At least 25 cases of cholestasis with bile duct injury have been reported (39,84), some proved by inadvertent rechallenge. Most of those affected are women. Abdominal pain is the most impressive symptom. It is often severe and resembles pain from other causes of cholangitis with which it is often confused, particularly because jaundice is usually present. However, the large bile ducts appear normal at cholangiography. Liver histology shows portal tract edema, irregularity and necrosis of the biliary epithelium, bile ductular proliferation, and a peribiliary infiltrate of neutrophils and eosinophils.

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Cholestasis is usually evident. Recovery occurs within 1 to 3 months of stopping dextropropoxyphene.

Nonsteroidal anti-inflammatory drugs NSAIDs are among the most commonly used prescription and nonprescription drugs, with up to 15% of the population using them in any 1 year. AT abnormalities are observed in up to 15% of patients taking NSAIDs, but overt hepatotoxicity is much less common with currently used agents. There are distinct differences in the frequency of hepatic injury associated with individual NSAIDs (469,470), with some agents being virtually free from reported hepatotoxicity and others such as bromfenac, benoxaprofen, and ibufenac having been withdrawn because of fatal liver injury (471) (Table 33.23). Several pharmacoepidemiologic studies have attempted to categorize risk factors associated with NSAID-associated liver injury and to also ascertain the hepatotoxic potential of individual NSAIDs. The results of these studies have been conflicting, which could be attributed to methodologic differences, including study settings (hospital vs. ambulatory care) and study definitions. Focusing on studies with significant clinical events (i.e., hospitalization and death), Rubenstein and Laine conducted a systematic review and found a slight (but not significant) increase in the risk of liver injury for current as compared to former NSAID users (odds ratio 1.2 to 1.7, P = not significant) (472). Contrary to general belief, women and the elderly were not found to be at greater risk. However, in another study carried out in an ambulatory care setting in France, gender differences were striking; after adjustment for confounding factors, there was a significant association between liver injury and NSAID use in women (odds ratio = 6.49 [1.67 to 25.2]) (473). Other risk factors identified in the Rubenstein review were rheumatoid P.964 arthritis (as compared with osteoarthritis) and use of nimesulide or sulindac.

Table 33.23. Liver Injury Associated with Salicylates and Nonsteroidal Anti-Inflammatory Drugs

Drug


Comments

Aspirin and other

Dose-dependent hepatocellular

Similar toxicity with sodium salicylate,

salicylates

injury; Reye's syndrome (febrile

mesalamine; diflunisal causes cholestasis

children)

Bromfenac

Acute hepatitis; fulminant hepatic

Withdrawn from clinical use

failure

Cyclo-oxygenase

Cholestatic hepatitis (few reports)

2 inhibitors

with celecoxib, rofecoxib

Overall incidence low

Clometacin

Acute or chronic hepatitis,

Fatalities recorded; female predominance

cholestatic hepatitis, cirrhosis,

(chronic hepatitis); some reported cases


were later found to have hepatitis C virus infection

Diclofenac

Acute hepatitis; chronic hepatitis

Women, older patients with osteoarthritis

Ibuprofen

Acute hepatitis; rarely vanishing

Hepatocellular injury with pirprofen,

bile duct syndrome; hepatotoxic

fenoprofen, flurbiprofen, ketoprofen;

potential is low

cholestasis (tiaprofenic acid)

Acute hepatitis, cholestasis;

Low incidence of toxicity

Indomethacin

massive hepatic necrosis (rare)

Naproxen

Mixed liver injury

Low incidence of toxicity

Nimesulide

Acute hepatitis; acute liver

Female predominance (with acute

failure; cholestasis

hepatitis)

Acute hepatitis, cholestasis,

Similar toxicity as oxyphenbutazone

Phenylbutazone


Piroxicam

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Hepatocellular, cholestasis,

Low incidence; isoxicam, droxicam cause

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massive/submassive hepatic

acute cholestatic hepatitis

necrosis (at least six reports)

Oxaprozin

Hepatocellular; fulminant

—

hepatitis

Sulindac


Hypersensitivity features common

(predominant), acute hepatitis

NSAID-associated hepatic disease encompasses a clinicopathologic spectrum from acute self-limited hepatitis, cholestasis, cholestatic hepatitis, and hepatic granulomas to fulminant hepatic failure, chronic hepatitis, and chronic cholestasis with ductopenia (471) (Table 33.23). Consistent with the diverse chemical structures of NSAIDs, both immunologic and metabolic idiosyncratic mechanisms have been invoked.

Sulindac Sulindac is structurally related to indomethacin but has been implicated more often in liver injury. Cholestatic reactions predominate, although appreciable hepatic inflammation was noted in 25% of cases (473a). Sulindac has also been associated with acute pancreatitis, and this may cause extrahepatic biliary obstruction. Women appear more susceptible to liver injury (female-to-male ratio 3.5:1). Approximately 70% of affected individuals are older than 50 years (473a). Hypersensitivity features are common, as evidenced by the presence of fever, eosinophilia, and cutaneous reactions, including the Stevens-Johnson syndrome; this indicates operation of the RMS. Resolution often follows drug cessation but protracted cholestasis can occur. The overall case-fatality rate is approximately 5%, attributable both to sequelae of systemic hypersensitivity reactions (such as Stevens-Johnson, nephrotoxicity) and liver injury.

Ibuprofen Ibuprofen rarely causes significant hepatic injury. In the few reported cases, the reactions have been hepatocellular or mixed hepatocellular–cholestatic (14). There are three case reports of VBDS, including two pediatric cases with associated Stevens-Johnson syndrome; two of these were referred for liver transplantation and the other had prolonged cholestasis (474,475). The presence of rash, fever, and eosinophilia suggests an immunoallergic basis. Rare cases of subacute liver failure have followed both overdose and therapeutic doses of ibuprofen. Explant histology showed submassive necrosis (474) or microvesicular steatosis (476). Recent reports of acute hepatitis induced by ibuprofen ingestion among HCVpositive patients are of interest but need to be confirmed by larger prospective studies (56).

Other propionic acid derivatives Bromfenac was implicated in several cases of acute liver failure resulting in death or necessitating liver transplantation (477). In most cases, treatment had been provided for more than 90 days before the patients developed malaise and fatigue, followed by symptoms of severe hepatitis that progressed to liver failure over 5 to 37 days. There were no extrahepatic features of drug allergy. The liver pathology showed confluent or zonal necrosis and a predominantly lymphocyte infiltrate. Other propionic acid derivatives associated with P.965 liver injury include fenoprofen, ketoprofen,pirprofen, and tiaprofenic acid (114) (Table 33.23).

Diclofenac Diclofenac has been implicated in more than 200 published cases of hepatic injury (478,479,480), some severe and with occasional fatalities. In several cases, causality has been proved by inadvertent rechallenge. Significant hepatotoxicity occurs in approximately 1 to 5 per 100,000 persons exposed (23). Acute hepatitis or mixed hepatocellular–cholestatic injury is characteristic, but chronic hepatitis resembling AIH has been reported (481). Women, the elderly, and patients with osteoarthritis appear to be susceptible to diclofenacinduced liver injury. A comparative study of diclofenac with nabumetone found a better safety profile for the latter in elderly patients, with no patient developing ALT level elevation greater than 2 × ULN as compared to 4% in the diclofenac group (482). However, the relevance of ALT level elevation to cases of overt liver disease is unclear. A prodromal illness or symptoms of hepatitis herald the onset of liver injury, most often within 3 months (range, 1 to 11 months) of starting diclofenac treatment. This is followed by jaundice and liver failure in severe cases. Fever and rash occur in 25% of cases. Liver tests usually reflect acute hepatitis, but some features of cholestasis may be present; jaundice occurs in 50% of reported cases (480). In some cases, the clinicopathologic features of ascites, hypoalbuminemia, and hyperglobulinemia indicate chronic liver disease. Liver biopsy specimens usually show acute lobular hepatitis, but confluent necrosis may be seen in severe cases; in chronic cases, periportal inflammation (interface hepatitis) and fibrous expansion of portal tracts are

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noteworthy. Resolution usually follows cessation of diclofenac, although fatalities have been recorded, particularly in elderly subjects. Corticosteroids were used successfully in a few cases of chronic diclofenac-induced hepatitis when no clinical improvement had been evident 3 months after drug discontinuation (479). Cross-sensitivity between NSAIDs is rare but has been reported with ibuprofen in a person with a history of diclofenac hepatitis; another had an adverse reaction to tiaprofenic acid (481). Pathogenic mechanisms involved in diclofenac toxicity include oxidative stress alone or in combination with mitochondrial injury (482,483). In certain cases, immune mechanisms may be relevant, especially in those presenting with chronic hepatitis. The presence of diclofenac metabolite–protein adducts in liver tissue raises the possibility of liver injury resulting from direct disruption of critical cellular functions or from elicitation of an immune response to these neoantigens (484). Supporting this hypothesis is the finding that certain polymorphisms favoring a T helper 2 (T H 2)-mediated antibody response were found more often among patients with diclofenac hepatotoxicity than in healthy controls and persons receiving diclofenac without hepatotoxicity (485).

Piroxicam The frequency of hepatic injury with this oxicam derivative is low (14). Acute hepatitis and cholestasis have been described, and there have been at least six cases of massive or submassive hepatic necrosis (14). The reaction appears to be dose independent, and immunoallergic features have not been conspicuous. Other oxicam derivatives implicated occasionally in cases of acute cholestatic hepatitis include isoxicam and droxicam (114).

Salicylates Aspirin causes dose-dependent hepatic injury, usually with increased AT levels. Overt jaundice is uncommon, occurring in less than 5% of those affected (14). Patients with hypoalbuminemia, juvenile rheumatoid arthritis, and SLE are especially susceptible to salicylate-induced liver injury (14). Hepatitis resolves rapidly after drug withdrawal and usually does not recur after reintroduction of salicylates at a lower dose. Blood levels of salicylate should not exceed 24 mg/L (14). Only one fatality has been recorded (486). Focal necrosis and lobular inflammation are usual. Other salicylates can cause similar injury (487). Epidemiologic studies have linked the use of aspirin in febrile children with Reye's syndrome but concerted public health campaigns have led to a major decline (near abolition) in the incidence of this disorder (see Chapter 56). Ticlopidine is not an NSAID but is discussed here with aspirin because it also inhibits platelet aggregation and is often used for similar indications. Unlike aspirin, ticlopidine-induced hepatotoxicity is dose independent and associated predominantly with cholestasis. More than 30 cases have been reported (82,488). Most cases have been found in individuals older than 55 years, reflecting the main use of ticlopidine as secondary prophylaxis against cerebrovascular and coronary artery disease. Onset of symptoms can be as early as 2 weeks, and in most cases is within 12 weeks of commencement. Rarely, symptoms may commence 1 month after the drug is withdrawn (489). Histology shows bland cholestasis, but cholestatic hepatitis with bile duct injury has been described. Recovery is usual within 3 to 6 months of stopping ticlopidine but occasionally may take longer than a year (490). Eosinophilia in some cases and a positive in vitro T-cell stimulation study to ticlopidine have been cited as favoring an immune basis for liver injury (491). Although corticosteroids P.966 appear to have aided recovery in one patient (492), their routine use cannot be justified in this older group of patients (mean age, 67 years); one report of cytomegalovirus-associated acute hepatitis after corticosteroid therapy in this setting is a timely reminder of the risks associated with steroid use in this older group of patients (mean age, 67 years) (493). Clopidogrel has been successfully substituted for ticlopidine in a patient with cholestasis. However, clopidogrel can itself rarely cause hepatocellular or hepatocellular-cholestatic injury (494).

Cyclo-oxygenase 2 inhibitors Celecoxib—in clinical trials, the frequency of hepatic dysfunction (0.8%) with this COX-2 inhibitor was not significantly different from that with placebo-treated (0.9%) subjects (495). However, celecoxib has been now incriminated in four reports of severe acute cholestatic hepatitis (114,496,497). Interestingly, two of these patients were allergic to sulfonamides; a history of sulfonamide allergy is considered by some to be an absolute contraindication to the use of celecoxib because there are structural similarities that predispose to hypersensitivity reactions. However, the implications of preexisting sulfonamide allergy are disputed by others (498), who contend that although celecoxib contains a sulfonamide moiety, it lacks the critical determinants that are implicated in sulfonamide allergy. One of the affected patients had alcoholic cirrhosis. This raises questions of celecoxib safety in persons with reduced hepatic reserve (497). Symptoms suggestive of liver injury develop 4 days to up to 3 weeks after commencing celecoxib. Pruritus, jaundice, and malaise are accompanied by a mixed hepatocellular–cholestatic biochemical profile. Peripheral eosinophilia has been observed in some cases, suggesting a possible immunoallergic mechanism. Resolution occurs within 4 months of discontinuing the COX-2 inhibitor. Rofecoxib, now withdrawn because of cardiovascular toxicity, was associated with a few reports of cholestatic hepatitis (114,499,500). Although the clinical features of liver injury resolved rapidly with drug withdrawal,

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complete biochemical recovery could be delayed for as long as 2 years. Nimesulide, another NSAID with preferential COX-2 selectivity, has also been associated with several instances of hepatocellular injury and cholestasis, and occasional cases of fulminant hepatic failure (501).

Allopurinol Granulomatous hepatitis is a typical feature of liver injury with allopurinol (502). Other manifestations include increased AT levels in asymptomatic persons, cholestasis, and hepatocellular injury, which can be occasionally severe enough to progress to fulminant hepatic failure. Severe centrilobular hemorrhagic necrosis resembling Budd-Chiari syndrome has also been described (503). Exfoliative dermatitis, fever, eosinophilia, interstitial nephritis, and microangiopathic vasculitis may be present in these cases. In a few severe cases, corticosteroids have been used with apparent benefit (504). Benzbromarone, a uricosuric agent, has been implicated in causing chronic hepatitis, cirrhosis, and fulminant hepatic failure (505).

Gold Hepatic toxicity of gold (gold sodium thiomalate) is usually characterized by mild cholestatic hepatitis. Onset is within 1 to 4 weeks of starting treatment. Fever, rash, and eosinophilia are often present. Liver biopsy specimens show canalicular cholestasis with minimal hepatocellular degeneration or portal tract inflammation. Resolution is the rule; fatalities are extremely rare (506). Rarely, prolonged cholestasis with ductopenia and other accompanying features of the VBDS (e.g., sialadenitis, sicca syndrome) can occur (507). Hypersensitivity features such as skin rash and peripheral and tissue eosinophilia were present in this case. Hepatocellular injury is less common but can be severe, resulting in death (508,509). This severe reaction to gold appears to be dose dependent and is more likely the consequence of metabolic toxicity than in cases presenting with cholestatic hepatitis. Submassive or massive hepatic necrosis with a mixed inflammatory infiltrate is observed on liver biopsies. Resolution can be slow (510). Gold accumulates in the lysosomes (“aurosomes”) in persons undergoing long-term crysotherapy. It has been proposed that liver injury occurs when the lysosomal storage capacity for gold is exceeded (510). Other gold compounds containing the same aurothio side group as gold sodium thiomalate (e.g., gold thiosulfate, aurothioglucose) are also associated with similar liver injury. Recently, acute cholestatic hepatitis has been reported after an overdose of gold potassium cyanide, a nonaurothio gold compound used in electroplating (511).

Penicillamine Used in the treatment of Wilson disease and as a disease-modifying agent in rheumatoid arthritis, Dpenicillamine has been associated with a range of side effects from nephrotoxicity to provoking autoimmune phenomena. Liver injury is less frequent. Most reports are of cholestatic hepatitis in association with hypersensitivity features (512). These occur within 2 weeks of commencing treatment. The prognosis is good, with resolution occurring within few weeks of cessation of penicillamine; fatalities are rare (513). P.967

Leflunomide Leflunomide is a disease-modifying antirheumatic drug. Its principal metabolite, A771726, is highly metabolized and eliminated through the liver. CYP 2C9 is probably involved in its metabolism. In clinical trials, 5% of recipients showed mild, reversible changes in AT. Concerns about significant liver toxicity were first highlighted by the European Medicines Evaluation Agency, which had received 296 reports of hepatic adverse effects, including 15 cases of liver failure; 9 of these cases had a fatal outcome. However, assigning a cause– effect relationship has proved problematic because many (78%) were receiving potential hepatotoxic drugs, including NSAIDs and methotrexate. Furthermore, other confounding factors were present such as alcohol use, abnormal baseline liver test results, congestive heart failure, and failure to comply with recommended doses. The low hepatotoxic potential of leflunomide compared with methotrexate was confirmed in two large cohorts involving over 40,000 patients (514). A special committee of the FDA concluded that the risk of hepatotoxicity was small with leflunomide, thereby permitting its continued usage (515). Special caution is advised when leflunomide is used with methotrexate. AT level increase is seen more often in persons receiving this combination (22%) as compared to recipients of methotrexate plus placebo (5%). However, normalization of AT levels was achieved without dose change (59%) or a single dose decrease (29%) (516). Nevertheless, continued vigilance is necessary because early changes of cirrhosis were observed in a patient taking both these drugs (516a). It has also been suggested that persons carrying a low–metabolizing activity polymorphism (e.g., CYP 2C9*3) may be at an increased risk of liver injury (517). The manufacturer recommends baseline and monthly monitoring of liver test results for the first 6 months, and every 2 months thereafter. Minor ALT level changes (100 g/week) were more likely to have advanced histologic changes (18%) and show histologic progression (73%) (29). Compared to those with rheumatoid arthritis, patients with psoriasis were also more likely to have advanced changes (7.7% vs. 2.7%) and histologic progression (33% vs. 24%). Finally, it is noteworthy that preexisting liver test result abnormalities are observed in 25% to 50% of patients with psoriasis and rheumatoid arthritis.

Table 33.24. Liver Injury Associated with Oncotherapeutic Drugs

Drug


ANTIMETABOLITES

Azathioprine

Cholestasis; vascular injury–peliosis hepatis, SOS (VOD)

Cytosine arabinoside

Raised AT level (with low dose), cholestasis or hepatocellular injury (high doses)

5-Fluorouracil

Rare liver injury with intravenous and intra-arterial route (particularly when associated with levamisole); floxuridine causes primary sclerosing cholangitis–like lesions

Gemcitabine

Transient AT level changes; cholestatic hepatitis leading to acute liver failure; SOS

6-Mercaptopurine

Bland cholestasis, hepatocellular or mixed injury; rarely fatal hepatic necrosis

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Methotrexate

Steatosis, hepatic fibrosis, cirrhosis

6-Thioguanine

VOD (in combination); peliosis; hepatocellular injury or cholestasis (rare)

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ANTIBIOTICS

Bleomycin

Low incidence of liver toxicity

Cyclosporine

Mild cholestasis (more accurately—impaired bilirubin transport), usually reversible with dose modification

Doxorubicin

Rarely acute or chronic hepatitis; hepatotoxicity enhanced by 6mercaptopurine

Dactinomycin

Hepatopathy–thrombocytopenia syndrome (with vincristine); clinically resembles SOS (VOD)

Daunorubicin

SOS (when used in combination treatment)

Mithramycin

Raised AT level (in up to 100%); occasionally centrilobular necrosis,

(plicamycin)

steatosis

Mitomycin C

SOS, steatosis

Mitoxantrone

Minor increase in AT level

SPINDLE INHIBITORS

Vincristine

Transient liver enzyme changes; synergistic with irradiation in producing liver injury

Paclitaxel, docetaxel

Minor increase in AT level

PLATINUM

Cisplatin

Liver injury rare

Raised AT level (high doses); steatosis, cholestasis, minor hepatic necrosis

Carboplatin

Acute liver failure (one case), SOS (with etoposide)

TOPOISOMERASE INHIBITORS

Etoposide Irinotecan,

Frequent liver test abnormalities (high dose); occasionally severe

topotecan

hepatitis (standard dose) Abnormal liver tests

ALKYLATING AGENTS

Low incidence of liver injury with this group

Busulfan

Cholestasis, porphyria cutanea tarda, nodular regenerative hyperplasia, SOS (in combination)

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Capecitabine

Hepatocellular

Chlorambucil

Hepatocellular, cholestatic hepatitis, acute liver failure

Cyclophosphamide

Hepatocellular, SOS (in combination), steatosis

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Ifosfamide

Liver injury rare; cholestasis (two cases)

Melphalan

Minor increase in AT levels

Thiotepa

Severe hepatotoxicity resembling phosphorus poisoning (rare)

NITROSOUREAS

BCNU, CCNU,

Minor increase in AT level; rare fatalities from liver injury (BCNU, CCNU)

streptozotocin

HORMONAL AGENTS

Aminoglutethamide

Cholestasis

Flutamide

Cholestatic hepatitis, fulminant hepatic failure; megestrol acetate associated with cholestasis

Tamoxifen

Steatosis, nonalcoholic steatohepatitis, rarely submassive hepatic necrosis, and cirrhosis

MISCELLANEOUS DRUGS

Amsacrine

Hepatocellular injury, cholestasis, rarely fatal hepatic necrosis

L-Asparaginase

Microvesicular steatosis, hepatic necrosis, coagulopathy (also with pegasparaginase)

Dacarbazine

SOS (VOD)

Procarbazine,

Hepatocellular injury

hydroxyurea

SOS, sinusoidal obstruction syndrome; VOD, veno-occlusive disease; AT, aminotransferases; BCNU, carmustine; CCNU, lomustine. Original references can be obtained from refs. 2, 14, and 518.

Table 33.25. Risk Factors for Methotrexate Liver Toxicity

Risk factor Age >60

Dose

Importance

Implications for prevention

Increased risk (reduced renal

Greater care in use of methotrexate for

clearance may contribute)

older people

Incremental dose

5–15 mg/wk very safe

Dose frequency

Weekly bolus (pulse) safer than daily

Duration of therapy

schedules

Cumulative (total) dose

Consider review of hepatic status every 2 to 3 y Review hepatic status after every 2 g methotrexate

Alcohol

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Increased risk with daily levels

Avoid methotrexate use if intake not curbed

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consumption

of >15 g (one to two standard

Consider pretreatment liver biopsy

drinks)

Obesity, diabetes,

Increased risk

metabolic

Consider pretreatment and progress liver biopsies

syndrome

Preexisting liver

Greatly increased risk

Pretreatment liver biopsy mandatory

disease

Particularly related to alcohol,

Avoid methotrexate, or schedule progress

obesity, and diabetes

biopsies according to severity of hepatic

(nonalcoholic steatohepatitis)

fibrosis, total dose, and duration of methotrexate therapy Monitor liver test results during therapy (see text)

Folate

Increased risk of liver injury in

supplements

persons not receiving folic acid

Systemic disease

Risk greater with psoriasis

Concurrent folate therapy recommended

None

than rheumatoid arthritis

Impaired renal

Reduced systemic clearance of

function

methotrexate

Reduce dose; greater caution with use

P.969

Clinical features and laboratory data Minor increases in ALT levels are seen 1 to 2 days after starting methotrexate treatment. These changes bear little relevance to the development of hepatic fibrosis, which can only be assessed by liver biopsy. Clinical features are absent or nonspecific for liver disease until complications of portal hypertension and liver failure develop. In these now rare advanced cases, hepatosplenomegaly, ascites, muscle wasting, thrombocytopenia, and hypoalbuminemia can be noted, but jaundice, hyperbilirubinemia, and coagulation disturbances are distinctly uncommon.

Histology The specific scoring system, devised by Roenigk et al. is widely used for grading liver histology in methotrexate users (521). In this system, grades I and II indicate a variable amount of steatosis, nuclear pleomorphism, and necroinflammatory activity but fibrosis is absent. Higher grades reflect increasing degrees of fibrosis, as follows: Grade IIIA (few septa), grade IIIB (bridging fibrosis), and grade IV (cirrhosis). The pattern of hepatic fibrosis includes striking pericellular fibrosis, a feature of both alcoholic steatohepatitis and NASH; the possibility that methotrexate itself causes steatohepatitis or accentuates fibrogenesis among persons with underlying “primary NASH” has been suggested (52). However, cases have been reported in which hepatic fibrosis appeared in livers with a relative paucity (or complete absence) of portal and lobular inflammation. Because the extent of hepatic fibrosis is the only important abnormality in those taking methotrexate, Richards et al. have proposed a new semiquantitative method for the evaluation of liver biopsy specimens in patients with rheumatoid arthritis (522). The objective is to provide greater sensitivity for detecting early hepatic fibrosis than the Roenigk system, and further validation will be of interest.

Prevention of methotrexate fibrosis Coprescription of folic acid is associated with a lower risk of liver injury (odds ratio [confidence interval (CI)] 0.10 [0.04 to 0.21]) (523) without sacrificing efficacy. However, its impact on preventing hepatic fibrosis is unknown (524). Guidelines have been published for monitoring methotrexate therapy (519,525,526,527) in patients with rheumatoid arthritis and psoriasis (summarized in Table 33.26). Less stringent guidelines for monitoring have been suggested. Yazici et al. have proposed less frequent liver tests (every 3 to 4 months), without additional risks but with reduced costs to the patient (528). However, the generalizability of these suggestions has been questioned because they have been based on a study population that was younger than that reported in other series and the patients were receiving lower doses of methotrexate (529). A revised threshold for liver biopsy has also been proposed (530). In this British retrospective study, advanced liver fibrosis was found in 2.6% and 8.2% of patients with psoriasis who had received a cumulative dose of 4 and 5 g, respectively. On this basis, liver biopsy was recommended after a cumulative methotrexate dose of 5 g (530). The value of liver biopsies, to P.970

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assess methotrexate hepatotoxicity in diseases other than psoriasis and rheumatoid arthritis, has not been established. In a study of 32 patients with inflammatory bowel disease receiving long-term methotrexate (mean dose 2.6 g; follow-up 131 weeks), histologic changes were common but minor, and significant hepatic fibrosis was rare (531). Similar considerations apply to methotrexate use in sarcoidosis; hepatic reactions were common, but it proved difficult to separate drug toxicity from sarcoidosis-related liver features (532).

Table 33.26. Guidelines for Monitoring Hepatotoxicity in Patients with Rheumatoid Arthritis and Psoriasis During Methotrexate Treatment

Approach

Psoriasis (Said 1997, Roenigk 1998)

Pretreatment

Routine liver tests, full blood count,

(laboratory

urinalysis, blood urea, creatinine,

tests)

creatinine clearance, hepatitis B/C

Rheumatoid arthritis (Kremer 1994) Same as psoriasis

serology

Pretreatment

Not mandatory

(liver biopsy)

Early treatment biopsy (2 to 4 m) in

Recommended in patients with history

patients with risk factors for liver

of excessive ethanol intake, abnormal

disease (past/current ethanol intake

baseline AST values, chronic hepatitis

greater than one to two drinks/d,

B or C virus infection a

abnormal liver test results, familial liver disease, diabetes, obesity, exposure to hepatotoxic drugs)

During

Liver tests 4 to 8 wk (1 wk after last

Recommended in patients with history

treatment

dose). Frequent monitoring during

of excessive ethanol intake, abnormal

(laboratory

initial treatment, dose escalation during

baseline AST, chronic hepatitis B or C

tests)

episodes in which blood MTX levels

virus infection

could be elevated (dehydration, impaired renal function, nonsteroidal anti-inflammatory drug use)

With significant and persistent abnormalities, withhold MTX 1 to 2 wk and repeat tests If abnormalities persist, consider liver biopsy

During

This is with no risk factors for liver

Liver biopsy recommended if five of

treatment

disease, and normal physical

nine AST determinations within 12 m

(liver biopsy)

examination and liver tests: Liver

(6 of 12 if tests performed monthly)

biopsy recommended after cumulative

are above upper limit of normal or

MTX dose 1.5 g b ; if biopsy is normal,

serum albumin level falls (less than

repeat at subsequent 1 to 1.5 g

normal) in controlled rheumatoid

cumulative dose c

arthritis

a

The authors agree that this should now be 2 to 4 g.

b

Additional 2 g cumulative dose (modified by earlier biopsy findings).

c

Current understanding would add “risk factors for nonalcoholic fatty acid liver disease/nonalcoholic

steatohepatitis, especially metabolic syndrome.” MTX, methotrexate; AST, aspartate aminotransferase.

Noninvasive methods of assessing hepatic fibrosis have been proposed for use during methotrexate therapy but have yet to be fully validated and adopted. These include measurement of serum procollagen-III peptide (PIIIP) levels (533) and dynamic hepatic scintigraphy. Doubts have been expressed about the reliability of PIIIP measurements in individual patients (534). Further, serial measurements are necessary to assess a dynamic process such as fibrogenesis (533). Dynamic hepatic scintigraphy evaluates the contribution of portal blood flow to the hepatic blood supply. Its application is based on the premise that changes in portal blood flow would be sensitive to structural alterations (534); a portal blood flow contribution of greater than 52% correlated with a 95% likelihood of normal liver histology.

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Azathioprine Azathioprine, the prodrug of 6-mercaptopurine, is used as an immunosuppressive agent or as a steroid-sparing agent in autoimmune diseases (see Chapter 31). Hepatic complications of azathioprine are rare but severe, diverse, and often of very late onset; all these factors provide a challenge for appropriate diagnosis and management. Disorders associated with azathioprine include bland cholestasis, cholestatic hepatitis with bile duct injury (535), zonal necrosis, and vascular toxicity (536,537). The latter encompasses diverse syndromes of SOS (VOD), peliosis hepatis, NRH, and noncirrhotic portal hypertension (537). HCC has also been recorded in a long-term recipient (538). Indirect hepatic effects of azathioprine such as opportunistic infections (e.g., cytomegalovirus) or, rarely, liver infiltration from lymphoma should always be considered. 6-Mercaptopurine causes dose-dependent hepatocellular necrosis, which can be fatal. Rarely, it is associated with cholestasis (14,539). Measuring 6-mercaptopurine metabolite levels (6-methylmercaptopurine) may be useful in making a diagnosis of drug hepatotoxicity in complex settings such as post–liver transplantation (539). P.971

6-Thioguanine Vascular toxicity, particularly hepatic SOS (VOD), is a characteristic feature of 6-thioguanine (6-TG) hepatotoxicity (Table 33.24) in the context of hematologic malignancies. Less well recognized is the development of NRH in persons with inflammatory bowel disease. In one study conducted in Los Angeles, 111 patients with inflammatory bowel disease receiving 6-TG were examined for potential hepatotoxic effects. Increase in liver enzyme levels and reduced platelet counts were found in 26% (540). These were seen more often in men and in those with preferential 6-methylmercaptopurine production during treatment with 6mercaptopurine or azathioprine. Liver histology was available in 38 cases. Reticulin-stained sections showed NRH in 20 (53%); conventional hematoxylin–eosin sections identified NRH in only 4 of these cases. Ultrastructural studies demonstrated sinusoidal collagen deposition in 60% (14 of 23), a figure significantly higher than that observed with conventional trichrome stains (34%). SOS (VOD) was observed in one case (541). NRH was present more often (76%) in patients with abnormal laboratory tests than among those without such abnormalities (33%).

Cyclosporin A Between 6% and 86% of organ transplant recipients receiving cyclosporine develop abnormal liver test results (14,542). However, these changes are mild and self-limiting, consisting of transient increase in SAP level, accompanied by a slight elevation in bilirubin and AT levels. Most patients do not develop symptoms of cholestasis or hepatitis. The biochemical changes are most evident in the first month after transplantation. However, up to 32% of cases may be associated with prolonged liver test abnormalities (542). Long-term recipients of cyclosporine are also at risk of developing biliary calculi (543), the consequence of altered bile flow and biliary lipid composition. Cyclosporine-induced liver test result abnormalities usually settle with dose reduction or discontinuation of treatment. There is anecdotal evidence that ursodeoxycholic acid may be beneficial in this setting (72). In experimental models, cyclosporine induces cholestasis by inhibiting Bsep-mediated taurocholate transport, culminating in decreased bile flow (544). It also disturbs bile salt kinetics by inhibiting bile salt synthesis, reducing the size of the bile salt pool, and increases cholesterol saturation in bile by reducing phospholipid secretion (see Chapter on cholestasis for details).

Sirolimus Increases in AT levels have been observed in liver and renal transplant recipients on sirolimus (545). Such cases were initially misdiagnosed as representing allograft rejection and were managed (unsuccessfully) with dose escalation. Resolution occurred only when sirolimus was withdrawn. Liver biopsy specimens show sinusoidal congestion or mild hepatitis.

Anticonvulsants Phenytoin Raised GGTP and SAP levels are very often observed in the absence of hepatic injury among people taking phenytoin; this usually reflects enhanced hepatic enzyme synthesis (a form of hepatic adaptation), but in those without adequate sunlight exposure, it is important to exclude vitamin D deficiency arising from enhanced hepatic metabolism of this vitamin. Acute hepatitis, including severe cholestatic hepatitis leading to VBDS, is a very rare but important side effect of phenytoin (2,546,547), usually as part of the RMS (Table 33.5). There may be an increased rate of hepatic reactions among African Americans compared with whites (546). Onset is usually within 6 weeks. Biochemical features reflect hepatocellular necrosis with high AT levels, but mixed patterns may occur. In phenytoin hepatitis, liver biopsy specimens show diffuse hepatocellular degeneration and multiple acidophilic (apoptotic) bodies, bridging necrosis, and a prominent lymphocytic or mixed cell inflammatory infiltrate containing neutrophils and eosinophils. Hepatic granulomas may also be present. The combined appearances of lymphocyte beading, mitotic hepatocytes, and granulomas resemble those observed in infectious mononucleosis (2).

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Phenytoin was one of the first drugs associated with hypersensitivity features now regarded as characteristic of the RMS (anticonvulsant hypersensitivity syndrome or “pseudomononucleosis” syndrome) (30). Fever, severe forms of rash, lymphadenopathy, leukocytosis, and Stevens-Johnson syndrome are frequent, and the key link is with visceral involvement including the liver, kidney, bone marrow, and lung (Table 33.5). Resolution occurs with phenytoin withdrawal, but the case-fatality rate of patients developing liver injury is up to 20%. Continued ingestion of phenytoin after the onset of symptoms is associated with a poor outcome. Treatment consists of supportive measures. Corticosteroids have not proved beneficial. Although the presence of hypersensitivity features suggests immunologic idiosyncrasy, it now seems likely that the primary abnormality is related to the generation of a highly reactive arene oxide metabolite. If detoxification of this metabolite by epoxide hydrolase is inadequate, it binds to cellular macromolecules P.972 or initiates oxidative stress, causing cell injury with apoptosis or necrosis. The way in which this reactive metabolite incites profound drug hypersensitivity is less clear, but neoantigenic determinants of immune reactivity, cytokine mobilization, and defects in cell defenses against oxidative stress and proinflammatory stressors are potential candidates. A genetic deficiency of this enzyme has been identified in patients and their family members (548). CYP 2C9 is a key enzyme in phenytoin metabolism. Phenytoin-associated VBDS has been described in a patient heterozygous for CYP 2C9*3 (an allele conferring low enzyme activity); this supports a pharmacogenetic basis for this adverse drug reaction (549).

Carbamazepine Liver disorders comprise approximately 10% of adverse drug reactions with carbamazepine (14). The frequency of liver injury is estimated at 16 cases per 100,000 treatment-years (14). Granulomatous hepatitis with varying degrees of hepatocellular injury and cholestasis have been reported (550,551,552,553,554). Children may also be affected, including neonates of women receiving carbamazepine during pregnancy (555). Onset is within 6 to 8 weeks. The hallmarks of hypersensitivity (e.g., fever, rash, angioedema, eosinophilia, and raised immunoglobulin E [IgE] levels) are often observed, linking this reaction as part of the RMS observed with other aromatic anticonvulsants (e.g., phenytoin, phenobarbitone) metabolized through arene oxides. Submassive or massive hepatic necrosis has been noted in a few patients. Multiple hepatocellular adenomas were described in a man receiving carbamazepine for 17 years (556), but there is no evident biologic basis for an etiopathogenic role of the drug in this syndrome. The case-fatality rate of carbamazepine hepatitis is 10% among those with hepatocellular reactions. Some reported cases of fulminant liver failure were also associated with concurrent acetaminophen intake or antituberculous therapy (557); the role of interactive hepatotoxicity needs to be considered in such severe cases. Patients presenting with granulomatous and/or cholestatic reactions usually survive, although bile duct injury and VBDS may rarely occur (88).

Lamotrigine Indications for lamotrigine include partial and generalized seizures and as adjunctive therapy in children with refractory epilepsy. Early reports of liver test abnormalities were wrongly attributed to status epilepticus. Subsequently, a small but definite risk of hepatotoxicity was documented (558). However, attributing causality can be difficult because other potentially hepatotoxic antiepileptic drugs are often coprescribed. Acute hepatitis was reported in ten persons, including two instances of fulminant hepatic failure. Symptoms developed within 2 to 3 weeks (range, 6 to 39 days). Extrahepatic features such as rash, disseminated intravascular coagulopathy, and rhabdomyolysis were sometimes present. Liver biopsy specimens showed acute hepatic necrosis or focal hepatitis with mild portal inflammation (558). Progressive hepatic necrosis culminating in fatal acute liver failure has been documented. In most other reported reactions, liver injury settled within a few weeks of stopping lamotrigine. Lamotrigine is structurally different from the aromatic anticonvulsants (e.g., phenytoin, phenobarbital, carbamazepine). Although in vitro cross-reactivity has been reported in patients with a history of reactions to the older antiepileptic drugs (559), there is no documented clinical cross-reactivity between lamotrigine and these agents.

Valproic acid (sodium valproate) Risk factors Up to 40% of recipients of VPA develop reversible increases in AT levels. These changes are frequently observed within in the first 2 months of treatment and are unrelated to the rare severe form of liver injury. VPA-associated hepatic injury is independent of dose and duration of treatment. It occurs predominantly in children, particularly those younger than 3 years. Among 37 fatal cases noted in a retrospective analysis of 400,000 persons taking VPA between 1978 and 1984, children younger than 10 years represented 73% (27 of 37 affected) (560). Risk factors include a family history of mitochondrial enzyme deficiencies (including urea cycle, long-chain fatty acid metabolism defects), Friedreich's ataxia, Reye's syndrome, having a sibling affected by VPA hepatotoxicity, and multiple drug therapy. There are 26 published cases of VPA liver toxicity in adults (561). The overall risk of liver injury among persons taking VPA is between 1 per 500 persons exposed among high-risk groups and less than 1 in 37,000 in low-risk groups (562).

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Onset, clinical features, and laboratory findings Symptoms begin 4 to 12 weeks after starting VPA and are often nonspecific; lethargy, malaise, poor feeding, somnolence, worsening seizures, muscle weakness, and facial swelling are important new symptoms among children prescribed VPA. They may be followed by features more readily attributable to hepatotoxicity, including anorexia, nausea, vomiting, weight loss, right upper quadrant discomfort, or abdominal pain. Jaundice, hypoglycemia, ascites, coagulation disorders, and encephalopathy indicate liver failure with imminent P.973 coma and death. Another presentation is associated with fever and tender hepatomegaly suggestive of Reye's syndrome. The prognosis is better in such cases. Yet others exhibit prominent neurologic features, such as ataxia and confusion with little evidence of hepatic involvement. Additional extrahepatic features observed among patients with VPA hepatotoxicity include thrombocytopenia, pancreatitis, and alopecia. The biochemical features resemble those described earlier for other mitochondrial hepatotoxins; a modest rise in bilirubin and ALT level is accompanied by hypoalbuminemia, hyperammonemia, and profound impairment in serum levels of clotting factors synthesized by the liver.

Pathology Histologic appearances include submassive or massive hepatic necrosis in two thirds of cases (562) and zonal or diffuse microvesicular steatosis in the others; steatosis may also accompany hepatic necrosis. Bile duct injury has been observed in a few cases, but as part of massive or submassive necrosis in which any additional significance is questionable.

Management, outcome, prevention Management, outcome, and prevention include supportive measures for underlying metabolic defects and managing acute liver failure. In one retrospective study, L-carnitine supplementation reduced mortality (563); 20 (48%) of 42 patients treated with L-carnitine survived, as against only 5 (10%) of 50 patients managed by aggressive supportive care alone. The place of liver transplantation is unclear; it has been performed successfully in some cases (564), but in others it led to worsening of neurologic disease (565). At least 60 deaths from VPA hepatotoxicity are recorded and the mortality remains high. Prevention is possible by adherence to prescribing guidelines; these include avoiding VPA in combination with other drugs in the first 3 years of life and in children with mitochondrial enzyme defects. Monitoring liver tests is unhelpful because of the high frequency of nonspecific liver test abnormalities. Children and their parents should be urged to report any new symptoms developing within the first 6 months of VPA therapy.

Mechanism of liver injury Unlike the aromatic anticonvulsants, VPA hepatotoxicity is rarely accompanied by manifestations of the RMS (566). Metabolic idiosyncrasy is probably the principal mechanism of VPA toxicity. Glucuronidation and βoxidation are the principal pathways of VPA metabolism, but VPA may be metabolized by CYP enzymes to 4-enVPA, a pathway that is accentuated in persons taking concurrent medications (particularly other anticonvulsants) that induce CYPs. Some VPA oxy-metabolites, and notably 4-en-VPA, inhibit mitochondrial fatty acid β-oxidation. Other metabolic effects of VPA therapy include secondary carnitine deficiency, therapeutic correction of which may be valuable (see preceding text).

Topiramate A woman receiving topiramate and carbamazepine developed acute liver failure. The explanted liver showed centrilobular necrosis (567). Another person prescribed topiramate for a bipolar affective disorder developed raised ALT level (>700 U/L), hypoalbuminemia, and mild hyperammonemia. Resolution occurred after topiramate was discontinued. Other medications including VPA could be resumed without ill effects (568). By contrast, topiramate used as an add-on anticonvulsant induced acute liver failure (569), which resolved only after VPA was withdrawn.

Felbamate Cases of acute hepatitis and fatal fulminant hepatic failure have been attributed to felbamate (570). Most affected individuals were women. The overall frequency of liver injury and liver-related death was estimated at 1 per 7,000 and 1 per 125,000 persons exposed, respectively. Half the reported cases occurred between 3 and 6 months (range 2 weeks to 8 months). Generation of atropaldehyde, a reactive metabolite, could be critical to felbamate toxicity (571). Felbamate should be reserved for treating refractory epilepsy, especially the Lennox-Gastaut syndrome.

Gabapentin Gabapentin has been implicated in causing cholestatic hepatitis (572). Another report of liver injury attributed to gabapentin has been disputed because other potentially hepatotoxic medicines had been coprescribed (573). The Committee on Safety of Medicines, the United Kingdom, has received reports of four other unpublished cases of jaundice, including one other cholestatic drug reaction. Overall, this drug has low hepatotoxic potential.

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Antipsychotic Agents, Sedative-Hypnotics, and Antidepressant Drugs Chlorpromazine Chlorpromazine is historically one of the most important causes of drug-induced liver disease, both because of the relatively high frequency of idiosyncratic reactions and because it is the archetypical example of a drug causing cholestatic hepatitis; VBDS and other P.974 complications, such as massive hepatic necrosis, also occur occasionally. Full descriptions of chlorpromazine hepatitis may be found elsewhere (2,14,574), but the essential features are recapitulated here because of what chlorpromazine has taught us about hepatic drug reactions and because the agent is still used occasionally. Chlorpromazine is associated with cholestatic hepatitis in 0.2% to 2% of recipients; the risk increases with age and is higher in women. The onset of prodromal symptoms occurs within 1 to 6 weeks (574). Fever and nonspecific systemic complaints are present in over half the patients, but rash is uncommon. Jaundice, pruritus, and generalized or right upper quadrant pain occur later. SAP level is elevated more than threefold, along with a moderate rise in the AT level and variable increase in serum bilirubin level, depending on severity. Peripheral blood eosinophilia is present in 10% to 40% of those affected. Liver histology is characterized by centrilobular cholestasis, portal inflammation, mild parenchymal injury, and occasionally bile duct damage (574). Resolution occurs within 12 weeks in most cases, but approximately 7% develop VBDS. The brisk response to rechallenge suggests immunoallergic idiosyncrasy but there is evidence of a toxic component to liver injury. Chlorpromazine and, particularly, its hydroxylated metabolites inhibit plasma membrane Na + /K + -ATPase, alter membrane fluidity, and polymerize actin. Genetically determined defects in sulfoxidation of chlorpromazine (the sulfoxide metabolite is inert) have been postulated but are unproved (575). A similar pattern of cholestatic liver injury has been described less frequently with prochlorperazine (576) and other neuroleptics such as haloperidol (577), pimozide, and sulpiride, including rare cases of VBDS (82).

Sedative-hypnotics Liver injury is extremely rare with the benzodiazepines and other minor tranquilizers, anxiolytics, or hypnotics. Both hepatocellular and cholestatic reactions are described, but often from times preceding the accurate diagnosis of all forms of viral hepatitis (14).

Antidepressants Monoamine oxidase inhibitors Iproniazid was one of the first drugs associated with acute hepatitis (2). These reactions occurred in 1% of recipients and were often severe, including instances of fatal fulminant liver failure. The hydrazine substituent (which iproniazid partly shares with INH, ethionamide, pyrazinamide, and nicotinamide) was probably the hepatotoxic moiety (578). Hydrazine sulfate can cause severe hepatorenal toxicity (578). Phenelzine and isocarboxazid have also been associated with occasional instances of hepatocellular injury, but monoamine oxidase inhibitors (MAOIs) are now rarely prescribed.

Tricyclic antidepressants Tricyclic antidepressants bear structural resemblance to the phenothiazines and are an occasional cause of cholestatic or, less commonly, hepatocellular injury. Recovery after drug cessation is usual, but prolonged cholestasis has been observed with amitriptyline (579) and imipramine (580).

Selective serotonin reuptake inhibitors and other modern antidepressants Liver enzyme level alterations in asymptomatic persons have been observed with fluoxetine and paroxetine (581). A few reports of acute and chronic hepatitis have been attributed to the use of selective serotonin reuptake inhibitors (SSRIs) (581) (Table 33.27). In all reported cases, the liver injury subsided with drug discontinuation. Nefazodone has been withdrawn after being implicated in the induction of acute and subacute liver failure (582). A Spanish pharmacovigilance study examining antidepressant hepatotoxicity found that nefazodone had the highest frequency of liver injury among these drugs (28.96 per 100,000 patient-years); the comparative figures for fluoxetine, paroxetine, sertraline, and citalopram were less than 2 per 100,000 patient-years (583). Of 32 cases of liver injury analyzed by the Canadian adverse drug-monitoring program, 26 (81%) were classified as severe. About half the patients recovered after drug withdrawal but three patients progressed to acute liver failure (584), necessitating liver transplantation. Centrilobular, massive or submassive hepatic necrosis was observed on histology. Two thirds of affected persons were women aged between 30 and 70 years. Although most had been taking the drug for 3 to 6 months, early liver injury (within 4 weeks) has also been reported (585). Bioactivation of nefazodone to a reactive quinone–imine species metabolite may underlie its hepatotoxicity (586). Trazodone has been implicated in cases of acute and chronic hepatocellular injury (587). The onset is usually within 6 months (range, 4 days to 18 months) (588). Positive rechallenge within 2 days of reinstituting the drug has been described (589). Recovery is complete within 2 months of discontinuing trazodone. Occasional

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reports note the occurrence of severe hepatotoxicity with combinations of antidepressants (590) or antidepressants with other neuroleptics (43). The liver toxicity associated with other antidepressants is summarized in Table 33.27 (591).

Table 33.27. Liver Injury Associated with Antipsychotic, Sedative-Hypnotic and Antidepressant Drugs

Drug

Nature of liver injury

ANTIPSYCHOTIC DRUGS

Chlorpromazine

Cholestasis; vanishing bile duct syndrome

Haloperidol

Cholestasis; vanishing bile duct syndrome

Clozapine

Hepatocellular, acute liver failure

Quetiapine

Acute liver failure (single case)

Risperidone

Raised aminotransferase levels, cholestatic hepatitis

SEDATIVE-HYPNOTICS

Barbiturates

Cholestatic or hepatocellular injury

Benzodiazepine

Hepatocellular, chronic hepatitis (bentazepam)

Chlormezanone

Cholestasis, hepatocellular, acute liver failure

ANTIDEPRESSANTS

Monoamine oxidase

Acute hepatitis

inhibitors

Tricyclic antidepressants

Hepatocellular or cholestatic; vanishing bile duct syndrome (amitriptyline, imipramine)

Tetracyclic antidepressants

Cholestasis with mianserin, maprotiline

SELECTIVE SEROTONIN REUPTAKE INHIBITORS

Fluoxetine

Acute hepatitis, chronic hepatitis

Paroxetine

Raised aminotransferase levels, chronic hepatitis (one case)

Sertraline

Acute hepatitis when used alone and also combination with other drugs, cholestatic hepatitis

Citalopram

Cholestasis

OTHER ANTIDEPRESSANTS

Bupropion

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Raised aminotransferase levels in trials; acute hepatitis (one case),

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cholestatic hepatitis

Fluvoxamine

Acute hepatitis

Nefazodone

Raised aminotransferases, occasionally subacute liver failure

Trazodone

Acute and chronic hepatitis, cholestasis, fatal hepatic necrosis

Venlafaxine

Acute hepatitis with zone 3 necrosis, mixed liver injury; low-dose venlafaxine associated with hepatocellular injury in a patient with chronic hepatitis B

P.975

Cognition Modifiers Tacrine (1,2,3,4-tetrahydro-9-acridinamine) Tacrine is a reversible cholinesterase inhibitor that was formerly used in treating Alzheimer's disease. Following initial concerns about possible hepatotoxicity, a seminal observational study was conducted (592). ALT values greater than the ULN were recorded on more than one occasion in 49% of recipients; 25% had values that were more than threefold elevated, and in 2% ALT level was more than 20-fold increased (values usually >1,000 IU/L). Among patients in whom treatment was discontinued because of abnormal liver enzyme changes, biochemical resolution invariably occurred, and 88% were able to resume long-term therapy (usually at lower dose); there were no fatalities (592). Only few cases of overt hepatic disease have been reported. Histologic appearances include mild lobular hepatitis, centrilobular hepatic necrosis, steatosis, and granulomatous hepatitis (593). The mechanism of tacrine-induced liver injury remains unclear. Hypersensitivity features were observed only infrequently and rechallenge also did not produce an exaggerated rise in ALT level. The frequency of combined glutathione-S-transferase genetic polymorphisms (M1 and T1) is increased in patients with tacrine-related liver injury (594), suggesting possible individual susceptibility to tacrine hepatotoxicity.

Donepezil Donepezil hydrochloride is a specific, reversible inhibitor of centrally active acetylcholinesterase. Although postmarketing surveillance has not yet revealed significant hepatotoxicity when used alone, fulminant hepatic failure has been reported in a patient taking both donepezil and sertraline (595).

Methylphenidate Methylphenidate is a sympathomimetic amine prescribed for attention-deficit disorders (ADDs) in children and narcolepsy and is also self-administered by intravenous injection for “recreational” use. Hepatocellular injury is documented with therapeutic (oral) and intravenous use (596,597). The latter reactions are more severe and have been associated with multiorgan P.976 failure involving the liver, kidney, pancreas, lung, and central nervous system (597).

Pemoline Pemoline is a psychostimulant previously prescribed for children with ADD. Clinical trials revealed mild, reversible liver injury in approximately 2% of recipients. However, instances of serious liver toxicity have since been reported to the FDA. Of 13 cases presenting with fulminant hepatic failure, 11 died or required liver transplantation (598). Symptoms were usually reported within 4 weeks but could be delayed for up to 1 year after starting therapy. Liver histology showed focal necrosis, mild steatosis, or portal inflammation (45). Rash, fever, or eosinophilia was infrequent (599). Moreover, the observation of a similar rise in serum AT level in twins with ADD supports a hypothesis of genetically determined individual susceptibility (51). On the other hand, the existence of distinctive cases of steroid-responsive chronic liver disease resembling AIH indicates that immunoallergic mechanisms could also be involved (600). Zimmerman suggested that persons prescribed pemoline should be monitored for serum AT changes, but it is noted that the onset of acute liver failure can be extremely rapid (599). This drug is no longer considered as first-line therapy for ADD and has been withdrawn in many countries.

Other Drugs Used in the Treatment of Neurologic Diseases Riluzole

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Riluzole is a glutamate antagonist approved for the treatment of amyotrophic lateral sclerosis. Increased ALT level was observed in 1.3% to 10% of clinical trial recipients. Two cases of acute hepatitis with microvesicular steatosis have since been reported, with onset at 4 and 8 weeks after starting treatment (601). Rarely, hepatocellular injury may be delayed for as long as 6 months (602). Liver test abnormalities settle shortly after riluzole is stopped.

Dantrolene Dantrolene is a skeletal muscle relaxant used against spasticity. The frequency of liver injury is approximately 1%. A feature has been the severity (the case fatality is approximately 28%) (603) of liver injury, which in some cases progressed even after stopping dantrolene. Most cases have been in people older than 30 years. Up to one third of affected persons had been asymptomatic, while others developed symptoms of hepatitis and jaundice. Hepatocellular necrosis, often submassive or massive, was the usual histologic characteristic (14,603). Chronic hepatitis and cirrhosis have also been observed (604). Liver tests should be performed every 2 weeks for the first 6 weeks of dantrolene therapy. The drug should be stopped if there is no clinical benefit. Other drugs with muscle relaxant properties, which have been rarely associated with liver injury include phenyramidol (hepatocellular injury), chlormezanone (cholestasis, hepatocellular injury, and acute liver failure), and baclofen (serum AT changes) (605,606).

Tolcapone Tolcapone is a catechol-o-methyl transferase (COMT) inhibitor used in the treatment of Parkinson's disease. In preclinical trials, significant ALT level elevations (>3 × ULN) were present in 1% to 3% of recipients. Tolcapone has now been implicated in at least four cases of acute liver failure (607), all in women older than 70 years. They presented with jaundice and high ALT levels. Centrilobular necrosis was observed at autopsy in one case. Ultrastructural changes included mitochondrial swelling with disruption of cristae and reduced matrix density. Patients developing severe hepatotoxicity had not been monitored as recommended, and it is noteworthy that significant liver injury has not been reported in correctly monitored recipients (608). In the United States, stringent monitoring guidelines consist of ALT testing every 2 weeks during the first year, and every 2 months thereafter. Drug withdrawal is suggested if the ALT levels exceeded the ULN. Because most cases of liver injury occur within the first 6 months, a panel of experts have suggested that less rigorous testing may be reasonable beyond this period and also that ALT levels up to two to three times ULN could be permissible (607,608). The mechanism of tolcapone hepatotoxicity could be related to uncoupling of mitochondrial oxidative phosphorylation (609). It is relevant that entacapone, another COMT inhibitor does not exhibit similar toxicity at comparable concentrations (609). As compared to tolcapone, entacapone has a greater binding affinity with glucuronidation enzymes but a lower capacity for penetrating the mitochondrial outer membrane (609). Of the three recent cases of hepatic injury attributed to entacapone, there were confounding factors in two cases such as underlying alcoholic cirrhosis and use of concurrent hepatotoxic drugs. The remaining case was of mixed hepatocellular–cholestatic injury, which could possibly be linked to this drug (610). Overall, the experience with entacapone (over 300,000 patient-years) has confirmed its generally safe track record. Manufacturers advise caution in persons with impaired liver function, but routine liver test monitoring is not mandatory (611). P.977

Drugs of Abuse 3,4-Methylenedioxymethamphetamine (“ecstasy”) Ecstasy is a widely used recreational agent that has been associated with more than 30 cases of acute liver injury, including several deaths from acute liver failure (612,613). In some European countries, 3,4methylenedioxymethamphetamine (MDMA) is recognized as an important cause of unexplained acute liver failure in young adults, accounting for up to 25% of such cases in Spain (614). Cases may go unrecognized in Asian countries where ecstasy use is a more recent phenomenon and viral hepatitis remains very common. Liver injury was initially described as part of a hyperthermic syndrome with rhabdomyolysis, acute renal failure, and coagulopathy; this was precipitated by vigorous muscle exercise, dehydration, and increased ambient temperatures, particularly during all-night “rage” dancing (613). However, it is now clear that acute hepatitis may be the sole manifestation of MDMA toxicity; it can occur following ingestion of even a single tablet, although many of the reported cases have involved consumption of MDMA for longer periods. MDMA is demethylated in the liver by the CYP 2D6 pathway. One initial suggestion was that persons with lowlevel expression of CYP 2D6 (the debrisoquine slow-metabolizer phenotype) may be susceptible to MDMAinduced hepatitis, but this has been challenged (615). Liver biopsy specimens may show acute lobular hepatitis, or zone 3 or massive hepatic necrosis, but others have observed chronic cases with hepatic fibrosis (616). Methylene dianiline (MDA) may be confused with MDMA (617) if used in similar settings. This is illustrated by a report of cholestasis in participants of a “technoparty” who had their alcoholic beverage spiked with MDA. Unlike MDMA, which primarily causes hepatocellular injury, MDA toxicity manifests as cholestasis, as exemplified by the 1965 outbreak of jaundice in Epping, England, where bread flour had been contaminated

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with MDA (618). Acute right upper quadrant abdominal pain (similar to erythromycin hepatitis) is a major feature.

Phencyclidine Severe phencyclidine (angel dust) overdose can lead to submassive hepatic necrosis (619) accompanied by hyperthermia, rhabdomyolysis, respiratory, and renal failure (14).

Cocaine Cocaine is a dose-dependent hepatotoxin in mice (45). Massive doses self-administered to humans cause liver injury in association with shock and other toxic phenomena (620,621). Rarely, cocaine can cause acute hepatitis without altered systemic hemodynamics and after intranasal (as opposed to parenteral) use (622). In rodents, the histologic lesions include extensive centrilobular, midzonal, or panlobular necrosis, together with microvesicular steatosis (14); gender and genetic differences, as well as the activity of CYP enzymes determine this varied histologic spectrum. Clinical presentation of cocaine hepatotoxicity is with raised serum AT level (>10-fold in 40% of cases), nearly always accompanied by hypotension, hyperpyrexia, renal failure, myoglobulinuria, and disseminated intravascular coagulation (623). The high mortality is illustrated by one series of 39 patients among whom more than 40% died (623). Thrombotic microangiopathy is a rare complication; early recognition and institution of plasma exchange can be lifesaving for this hematologic disorder (624). The mechanism of liver injury may vary between species; in rodents it involves drug metabolism to toxic, oxy- or nitrometabolites and factors pertaining to host defenses (2). In humans, systemic hypotension and hypoxia (and possibly hyperthermia) are more likely to contribute to liver injury (623) than the direct effects of cocaine on the liver. Induction of hepatic CYP 2E1 by alcohol can potentiate the hepatotoxic effects of cocaine experimentally (625).

Drugs Used in Aversion Therapy and Treatment of Alcohol Withdrawal Tetrabamate (Atrium) Tetrabamate is a drug combination (i.e., febarbamate, difebarbamate, and phenobarbital) that has been used in France and Spain to treat alcohol withdrawal, tremor, and depression. Phenobarbital is an extremely rare cause of liver injury (cases are similar to phenytoin hepatitis) (626), while difebarbamate and febarbamate have not been previously implicated in hepatotoxicity. However, use of the combined preparation (tetrabamate) has been implicated in causing acute hepatitis (626). Onset of symptoms was between 15 days and 2 years after commencement of drug ingestion (627). Complete recovery was observed in most patients after drug cessation, but two deaths from liver failure were recorded; both fatalities were in persons who continued taking tetrabamate after the onset of symptoms. Histology shows acute hepatocellular necrosis. Other lesions described include cholestasis, microvesicular steatosis, and granulomatous hepatitis. Hypersensitivity features were prominent in some individuals, including the presence of ANAs and/or SMAs. Therefore, immunologic idiosyncrasy may contribute to liver injury, but genetic differences in drug P.978 metabolism could have also been responsible (628). Phenobarbital, a potent CYP enzyme inducer, could also have potentially enhanced the production of toxic metabolites from the other constituents (as in the case of VPA and the anticonvulsant hypersensitivity syndrome [RMS]) when used in drug combinations.

Disulfiram Disulfiram has been incriminated in at least 30 instances of acute hepatocellular injury. Recovery usually occurs within 2 weeks, but liver test results can take up to 3 months to normalize. The high AT readings distinguish these reactions from alcoholic hepatitis. Rarely, acute liver failure may develop (629,630). The frequency of fatal liver injury is estimated at 1 per 30,000 treated persons per year. Three liver transplantations have been performed for disulfiram-induced acute liver failure, the youngest patient being only 16 years old (631). Baseline and serial liver test monitoring is recommended for persons receiving disulfiram therapy. Cyanamide produces a characteristic ground glass appearance of hepatocytes, which resembles Lafora bodies (632). This is a form of hepatic adaptation rather than liver injury. The intense immunohistochemical staining of these cytoplasmic inclusions with a polyglucosan-reactive monoclonal antibody suggests that they are derived from altered glucose metabolism (633). However, cyanamide can rarely cause acute hepatitis, and serial liver biopsy specimens from alcohol-abstinent recipients of cyanamide showed portal–portal and portal–central fibrosis (634).

Chlormethiazole Used for years to treat alcohol withdrawal symptoms, chlormethiazole had been previously associated with only one report of acute cholestatic hepatitis. However, a recent case series suggests that chlormethiazole is associated with greater hepatotoxic potential than previously appreciated (635). All three affected persons were older than 70 years and had been taking the drug for less than 2 months for indications other than alcohol withdrawal (e.g., insomnia, depression). The biochemical profile reflected hepatocellular or mixed liver injury. One developed fatal acute liver failure; histology showed submassive necrosis. The other two patients recovered within 2 months. The authors speculated that chlormethiazole hepatotoxicity may be underreported

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in the context of alcohol withdrawal because of difficulties in separating drug toxicity from the underlying alcoholic liver disease (635).

Antihistamines: H 1 Receptor Antagonists Cetirizine Cetrizine is a nonsedating H 1 receptor antagonist associated with transient liver enzyme abnormalities in less than 2% of recipients. Cetirizine has been implicated in four reports of liver toxicity; three were hepatocellular reactions and in the other the patient developed cholestasis (54,636). Appearance of a rash (637), eosinophilia, and presence of anti–liver/kidney microsomal antibodies in two cases (637,638) is suggestive of drug hypersensitivity. Positive rechallenge (inadvertent) has been reported (638). Other H 1 receptor blockers that have been associated with cholestatic drug reactions include terfenadine,cinnarizine, chlorpheniramine, and pizotyline (82). Temporal relationship of loratadine to two hepatocellular reactions has been described. One of these cases developed subfulminant hepatic failure and needed liver transplantation. Liver histology showed massive hepatic necrosis (639).

Gastric Acid–Lowering Agents H 2 receptor antagonists

Rare episodes of liver injury have been reported with most H 2 receptor antagonists (640). Cross-reactivity between famotidine and cimetidine has been described (641), but there is no overall evidence of a class effect on hepatotoxicity among these structurally variable drugs. Although these agents have a good safety profile, serious hepatotoxicity has led to the withdrawal of oxmetidine, ebrotidine, and niperotidine. Compared to nonusers, the relative risk for liver injury was 5.5 for cimetidine and 1.7 for ranitidine (and 2.1 for omeprazole) (642). The frequency of hepatotoxicity with cimetidine and ranitidine has been estimated at 3 to 6 per 100,000 and 1 per 100,000 prescriptions, respectively (643). The risk of liver injury with cimetidine is highest with doses exceeding 800 mg/day and at the onset of treatment. Cimetidine, ranitidine, and famotidine usually cause acute hepatitis or cholestatic hepatitis (643). Of 170 cases of H 2 receptor antagonist toxicity reported to the Australian Adverse Drug Reaction Advisory Committee, hepatotoxicity constituted 4% to 8% of reactions. Most of the affected individuals were older than 50 years (643). Hepatic reactions were more frequently reported with ranitidine than with cimetidine or famotidine. Supportive evidence of hypersensitivity features was recorded in a few patients. Others have reported Stevens-Johnson syndrome in association with ranitidine in two patients with preexisting severe liver disease; it was suggested that altered hepatic metabolism may have contributed P.979 to the syndrome, but no data were presented to support this (644). However, others point out that markers of hypersensitivity and positive rechallenge have not been consistently demonstrated, leading them to propose an alternative hypothesis for liver injury (645). In a rat model, they showed that significant hepatocellular injury could be elicited in the presence of lipopolysaccharide-induced liver inflammation. On this basis, they suggest that similar mechanisms may underlie human ranitidine hepatotoxicity because these cases are preceded by a cluster of symptoms (e.g., fever, diarrhea, abdominal pain) that could be explained by endotoxemia. In turn, the ensuing endotoxemia-related hepatic inflammation could render the hepatocytes susceptible to ranitidine-related liver injury. Interestingly, in the same rat model, coadministration of lipopolysaccharide with famotidine, a less frequent cause of hepatotoxicity, did not elicit significant liver injury.

Proton pump inhibitors A few reports of acute hepatitis or mixed hepatocellular–cholestatic liver injury (646) have been ascribed to the proton pump inhibitors (PPIs). Although omeprazole was implicated in one case of fulminant hepatic failure, concurrent acetaminophen use was not clearly excluded (see earlier) (646). Fulminant hepatic failure has also been attributed to rabeprazole (647). However, the role of rabeprazole in causing fulminant hepatitis appears equally less conclusive because terbinafine had also been prescribed. The authors’ assertion that terbinafine hepatotoxicity is usually mild is not consistent with other data presented to the FDA (see earlier section).

Antispasmodic Drugs Alverine Alverine is a smooth muscle relaxant used to treat patients with irritable bowel syndrome. Two cases of acute hepatocellular injury have been reported. In the first report, the accompanying peripheral and tissue eosinophilia along with ANAs directed against a component of the nuclear envelope (lamin A and C) suggested immune-mediated liver injury. These features were absent in the second case. Both patients recovered after alverine was discontinued (648,649).

Emerging Drugs A clinical challenge with drug-induced liver disease is provided by instances of hepatotoxicity attributable to recently introduced drugs (Table 33.28). The frequency of liver injury with these drugs will not be known until

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larger studies are conducted.

Alfuzosin Two reports of liver injury (i.e., hepatocellular and mixed hepatocellular-cholestatic) have been recorded with alfuzosin, a α 1 -adrenoceptor antagonist used in treating benign prostatic hyperplasia (650,651). One of these patients had underlying chronic liver disease (651). Because alfuzosin is extensively metabolized in the liver, it is possible that the ensuing hepatotoxicity in this case was a consequence of increased drug levels. Normalization of liver test results was complete within 6 months of stopping the drug (650,651).

Bosentan Bosentan is an endothelin antagonist prescribed for primary pulmonary hypertension, chronic heart failure, and hypertension. Dose-dependent, reversible AT level increases (up to 3 × ULN) were observed with 10% of clinical trial recipients. In a pivotal trial of patients with primary pulmonary hypertension, AT level increases of eight times ULN were observed in 3% and 7% of those assigned to the 125 mg b.i.d. and 250 mg b.i.d. arms, respectively (652). The pharmacokinetics of bosentan is unaltered by mild hepatic P.980 function impairment (Child-Pugh A) (653) but the drug is contraindicated if more severe liver disease is present. However, an area of study is the use of bosentan in controlling portopulmonary hypertension (654,655).

Table 33.28. Liver Injury Associated with Emerging Drugs

Drug

Nature of liver injury

Alfuzosin

Hepatocellular or mixed hepatocellular–cholestatic injury

β-Interferon

Raised AT level common; clinically significant liver injury rare; can trigger autoimmune hepatitis

Bosentan

Raised AT level in at least 10% but clinically significant liver injury not described; raised AT level also observed with sitaxsentan

Orlistat

Cholestatic hepatitis, subacute liver failure (single cases only)

Imatinib mesylate

Raised AT level in 35%; acute hepatitis; massive or submassive hepatic necrosis (rare)

Infliximab

Bland cholestasis, cholestatic hepatitis with bile duct injury; acute liver failure (rare); reactivation of chronic hepatitis B

Leukotriene antagonists

Zafirlukast

Submassive or massive hepatic necrosis

Montelukast

Acute hepatitis, cholestatic hepatitis

Ximelagatran

Raised AT in 6%; acute liver failure (relationship with drug not definitely established)

AT, aminotransferase.

In a rat model, bosentan inhibited canalicular Bsep (656). Further, coadministration of cholestasis-inducing agents such as glibenclamide (glyburide) is associated with an increased frequency of AT level elevations (29%). Bosentan-treated patients with chronic heart failure also appear to be at an increased risk of liver injury, with up to 18% showing AT level elevations in one study. Dose-dependent AT increases were also reported with sitaxsentan, a selective endothelin (ET A ) receptor antagonist. The cumulative risk of developing raised AT level (up to 3 × ULN) with the 100 and 300 mg daily dose after 9 months was estimated at 8% and 32%, respectively (657).

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Orlistat This gastrointestinal lipase inhibitor was not associated with hepatic side effects in clinical trials. Abnormal AT levels were noted on routine evaluation in an obese young woman 3 weeks after beginning orlistat. She developed subacute liver failure 2 weeks later and required liver transplantation (658). Explant histology showed massive hepatic necrosis. Other reports of liver injury include an instance of fatal massive hepatic necrosis and a case of acute cholestatic hepatitis (659). Other than these three reports, orlistat has not been implicated in causing significant liver injury. Further, it has been studied as a potential therapeutic agent in patients with NAFLD.

Interferons Interferon-α has been associated with acute “flares” in patients with hepatitis C, sometimes resulting in viral clearance (see Chapter 26). It may also rarely activate latent AIH (660). This may occur if the autoimmune etiology of chronic hepatitis has been not correctly appreciated at diagnosis, or it may represent a direct immune-mediated complication of interferon. β-Interferon is increasingly used as a first-line agent in relapsing–remitting multiple sclerosis, as well as for hepatitis C in Asian countries. Analysis of pooled data from six randomized controlled trials involving over 2,800 subjects has shown that AT level increases are frequent (67% of subjects by 24 months) (661); most (75%) of these increases occur within 6 months. AT level changes settled spontaneously or after dose reduction (in 5%), and only a minority (0.4%) had their medication withdrawn. A retrospective chart review of 844 patients in British Columbia compared three different preparations of interferon-β-1b with respect to their hepatotoxic potential (662). AT level increases of up to 2.5 × ULN, 5 × ULN, and greater than 5 × ULN were found in 23% to 39%, 1.9% to 7.8%, and 0% to 1.9% of patients, respectively; the lowest figures were recorded with the intramuscular preparation of interferon-β-1b. Despite the high frequency of AT level changes observed with the β-interferons, clinically significant toxicity is rare. Of the two reported patients developing fulminant hepatic failure (622), one was also receiving nefazodone. Unmasking of AIH has also been observed with β-interferon (663,664). Baseline and periodic liver test monitoring is recommended by the manufacturers (665). Pegylated interferon-α has a higher rate of AT abnormalities than conventional recombinant interferon-α but clinically significant hepatotoxicity has not been reported.

Imatinib mesylate Imatinib mesylate is a tyrosine receptor kinase inhibitor that has been approved for treating chronic myeloid leukemia and advanced gastrointestinal stromal tumors. Nonhematologic adverse effects include sodium retention (resulting in pleuropericardial effusions, pulmonary edema, and ascites) and abnormal liver test results. Raised AT and/or serum bilirubin levels were observed in up to 3.5% of individuals treated. Median time to onset of raised AT and/or bilirubin levels was 100 days (666). These abnormalities usually settled with dose reduction; the drug needed to be discontinued on account of hepatotoxicity in only 0.5% of recipients. Few reports of acute hepatitis have accrued (666,667), including three cases of acute liver failure (668,669); concurrent acetaminophen intake was recorded in one of these cases. Positive rechallenge was observed in two patients with chronic myeloid leukemia (666). Histologic appearances showed acute hepatitis with extensive lobular and portal inflammation (670) or focal hepatic necrosis in less severe cases and submassive hepatic necrosis in those presenting with acute liver failure (669).

Leukotriene Antagonists Leukotriene antagonists are a group of drugs used to treat asthma and include zileuton, zafirlukast, and montelukast. As a group, reversible increases in AT levels (>2 × ULN) were recorded in up to 3% of leukotriene antagonist (LTA) recipients in preclinical trials. Zileuton, the first member of this drug class, was implicated in a single case of acute hepatocellular injury. It has been superseded by zafirlukast and montelukast (671). P.981

Zafirlukast Collated global surveillance data published by the manufacturers on-line indicate over 100 cases of disturbed liver function in zafirlukast users. These include 46 reports of hepatitis and 14 of acute liver failure. The risk of developing acute liver failure was estimated at less than 1 per 100,000 patient-years. Assigning causality is difficult because details of concomitant drug intake or preexisting liver disease were not provided. Nevertheless, detailed descriptions of clinically significant hepatic injury have been published elsewhere (672,673). In these two case series, jaundice was observed in seven of nine cases. Two patients progressed to acute liver failure and needed liver transplantation. Symptoms were delayed until 6 months (range, 1.5 to 13 months) after starting zafirlukast. Inadvertent rechallenge reproduced liver injury in one case. Submassive or massive hepatic necrosis was observed in the hepatic explants. It is important to note that in persons developing acute liver failure preceding signs and symptoms of hepatitis were not always present. The apparent response to corticosteroids in four patients, three of whom had hypersensitivity features such as skin rash, and peripheral and tissue eosinophilia suggestive of immune-mediated liver injury. However, in another report the absence of hypersensitivity features and the long latent period (13 months) are more consistent with idiosyncratic liver injury (674). Cross-reactivity with montelukast has not been described (673). Periodic

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monitoring of liver tests is suggested (671). However, the long latent period to liver injury in some cases, lack of preceding symptoms, and also the progression of liver injury even after drug withdrawal cast doubts on the validity of routine surveillance (671).

Montelukast Three reports of acute hepatitis have been documented with montelukast. Time to onset of liver injury has been variable (1 month to 2 years) (675,676,677). Recovery was complete in all cases. Biochemical resolution can be slow and AT level (>2 × ULN) remained elevated for more than 1 year after drug withdrawal. Liver histology showed acute hepatitis or cholestatic hepatitis (676,677). A lymphocyte transformation test was reported as positive in one case, supporting a cause–effect relationship (676).

Infliximab Infliximab is an anti–tumor necrosis factor monoclonal antibody used in refractory rheumatoid arthritis and Crohn's disease. Transient AT level elevations were recorded in combination with methotrexate but no major hepatic adverse effects were noted in clinical trials. Two reports of liver injury have since emerged in the early postmarketing phase. Bland reversible cholestasis was noted in one case and acute hepatitis with bile duct injury, interface hepatitis, and antibodies to double-stranded DNA in another (678,679). Smooth muscle and anti–liver/kidney microsomal antibodies were not present. Whether infliximab is directly hepatotoxic or whether it triggers autoimmune hepatocellular and bile duct damage is not clear. Two further reports of infliximab hepatotoxicity have since accrued. Fulminant hepatic failure developed in a 28-year-old woman with adult-onset Still's disease, 10 days after the second infliximab infusion. She was hepatitis B surface antigen positive, although there was no evidence of liver disease or viral replication (680). However, other potential factors to be considered in this case are the use of concurrent hepatotoxic drugs (cotrimoxazole) and also the risk of hepatic failure with Still's disease (681). There are now two well-documented cases of chronic hepatitis B reactivation after infliximab treatment in patients with Crohn's disease; a third patient with chronic hepatitis B who was receiving lamivudine was unaffected, suggesting that serologic screening and antiviral prophylaxis are appropriate for persons with chronic hepatitis B who commence infliximab treatment (682).

Ximelagatran Ximelagatran is a thrombin inhibitor associated with increased AT levels (>3 × ULN) in 7.9% of long-term recipients, occurring most often within 6 months of commencement. Most (96%) of these biochemical changes declined slightly to less than twofold above ULN irrespective of whether the drug was continued or withdrawn. Symptomatic cases have been rare (683). Three cases of acute liver failure have been attributed to this drug but a definitive relationship has not been clearly established. At the present time, FDA approval has been withheld because of concerns about hepatotoxicity.

Hepatotoxicity of Herbal Medicines The potential therapeutic benefits of herbal medicines in liver disease have yet to be fully defined, as reviewed elsewhere (683,684). However, the growing popularity of CAM in industrialized societies has brought about an increasing number of cases of herbal hepatotoxicity (685). Many of the herbal products have been used for centuries, in part because of their excellent safety record, so that recognition of hepatotoxicity has seemed surprising. Explanations include nonadherence to recommended doses and concurrent intake of other agents, including conventional medicines (such as acetaminophen). Toxicity may also result from the P.982 use of newer more biologically active formulations. For instance, a 78-year-old woman developed acute hepatitis soon after using a readymade powder formulation of a fungal extract Linghzi (Ganoderma lucidum) despite having used this herbal compound previously for a year without toxicity (686). The only difference was that earlier treatment had been home prepared and presumably was not as concentrated as the marketed product that caused the adverse reaction. Individual susceptibility may also be an important determinant of herbal toxicity. Kava, a reasonably safe and widely used anxiolytic agent with rare hepatotoxicity, appears more likely to cause acute hepatitis (687) in whites with the slow debrisoquine phenotype (low expression of CYP 2D6) (also see “Kava”). The same phenotype has also been implicated in facilitating senna-associated hepatocellular injury; altered pharmacokinetics with prolongation of serum half-life and high metabolite levels were demonstrated (688). In comparison with these agents, others such as the pyrrolizidine alkaloids have substantial hepatotoxic potential. Some herbal preparations (e.g., Jin Bu Huan) could incite an immunoallergic mechanism of liver injury. Others could aggravate preexisting liver disease, as noted with Ma huang, which can exacerbate AIH (689). Rarely, herbal medicines may trigger latent AIH (e.g., Dai-saiko-to, Black cohosh) (690,691,692). Such interactions between herbal medicines and preexisting liver disease are poorly understood. This is an important aspect because many patients with viral hepatitis use herbal remedies, and disclosure is not always forthcoming. Recurring themes among reports of herbal hepatotoxicity are delayed diagnosis, product contamination, or botanical misidentification (685). The latter two issues can be rectified by exclusive use of agents prepared according to codes of good manufacturing practice; relevant legislation governing the sale of herbal products is in place in some countries, but the international availability of herbal medicines by mail and Internet ordering partly abrogates such improvements. Greater awareness of possible herbal hepatotoxicity is required on the part of physicians and the public so as to avoid the problem of delayed diagnosis; the implications of continued intake of hepatotoxic chemicals after the onset of liver injury is identical whether it is a

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conventional medicinal agent or a herbal product. Natural products, often equated with “safety,” may be easily overlooked by patient and doctor. Items not readily identified include skin creams, “natural” sedatives, herbal tea infusions, health tonics, and so-called energy vitalizers. Some herbal products can complicate the management of patients with chronic liver disease by exacerbating a bleeding tendency (e.g., ginkgo) or by antagonizing the antimineralocorticoid action of spironolactone (e.g., glycyrrhizin, licorice) (685). Agents with immunostimulant actions, such as Echinacea and St. John's wort, can interfere with immunosuppressive therapy and provoke allograft rejection (693). Herbal hepatoxicity encompasses a range of hepatic pathology from acute hepatitis, steatosis, and fibrosis, through to SOS and submassive or massive hepatic necrosis. Table 33.29 provides an updated account of contemporary agents implicated in significant liver injury, and some well-characterized and illustrative examples are briefly outlined in the subsequent text. More detailed accounts are available in recent reviews (685,693).

Chaparral Chaparral (Larrea tridentata) is marketed as tablets, capsules, or herbal tea infusions. It is used as a dietary “energy” supplement and as a cure for numerous ailments ranging from chicken pox to cancer. Cholestatic hepatitis is the predominant mode of presentation, but chaparral has been associated with acute hepatitis, subacute hepatic necrosis, and acute liver failure (694). Hepatotoxicity is at least partly dose dependent; dosage recommendations were exceeded in some severe cases (694). At least three patients have developed end-stage liver disease requiring hepatic transplantation.

Germander Used as a traditional remedy for many centuries, germander became popular as a slimming aid in the 1980s, particularly in France and Italy. More than 30 cases of liver injury were recorded, mostly in middle-aged women. Acute hepatitis developed 8 weeks after ingestion of germander capsules or herbal teas (695). Presence of ANAs, SMAs, and, transiently, antimitochondrial M2 antibodies have been recorded occasionally (696). Although most patients recovered, several fatalities from liver failure have been recorded. In some individuals, chronic hepatitis or cirrhosis was evident at presentation. Other case studies suggest that unfavorable outcomes are related more often to continued or repeated drug ingestion after the onset of liver injury. Early recrudescence of liver test abnormalities after rechallenge is suggestive of immunologic idiosyncrasy. The identification of a microsomal target for germander-induced autoantibodies is consistent with this proposal (697). On the other hand, the demonstration that the constitutive neoclerodane diterpenoids in germander are metabolized by CYP 3A enzymes to epoxides that can deplete GSH and incite oxidative stress– dependent apoptosis favors a reactive metabolite mechanism of liver injury (698). Herbal products derived from closely allied medicinal plants Teucrium polium L. and Teucrium capitatum L. P.983 P.984 have also been associated with acute liver failure and acute hepatitis with bridging necrosis, respectively (699,700).

Table 33.29. Herbal Remedies and Dietary Supplements Implicated as Causing Toxic Liver Injury

Herbal remedy

Indications

Toxic constituent


Atractylis

Purgative, emetic,

Potassium atractylate

gummifera

diuretic

and gummiferin

Acute liver failure

Black cohosh

Menopausal

Not known; contains

Acute liver failure; can

symptoms

diterpenoids

trigger autoimmune hepatitis

Chaparral leaf

Multiple uses

Larrea tridentate

Zone 3 necrosis; massive hepatic necrosis chronic hepatitis; cholestasis

Chaso

Slimming aid

N-Nitrosofenfluramine

Submassive or massive hepatic necrosis, acute hepatitis

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Chinese herbal

Multiple

Many; Dictamnus

Liver injury (no

medicines (see

indications; skin

dasycarpus present in

histology); acute

text)

diseases; health

six cases (in

hepatitis; SOS;

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tonic; viral

combination)

hepatitis

Comfrey; gordolobo

Health tonic

yerba tea; maté

vanishing bile duct syndrome

Pyrrolizidine alkaloids;

SOS (veno-occlusive

compositae

disease)

Cyclic terpenes

Abnormal liver tests,

tea; Chinese herbal tea

Camphor

Rubefacient

encephalopathy

Carp capsules (raw

Rheumatism, visual

carp gallbladder)

acuity

Cyprinol

Liver enzyme changes (no biopsy) with acute renal failure; hepatic necrosis (rats)

Cascara sagrada

Dai-saiko-to (TJ-9) a

Laxative

Liver disease,

Many constituents,

Cholestatic hepatitis,

possibly anthraquinones

portal hypertension

Scutellaria; glycyrrhizin

Acute and chronic

especially chronic

hepatitis

viral hepatitis

Greater celandine

Gallstones

Chelidonium majus

Acute hepatitis; cholestatic hepatitis; fibrosis

“Green juice”

Dietary supplement

Contains vegetable

Granulomatous hepatitis

extracts, micronutrients

Germander (tea,

Weight reduction;

Neoclerodane diterpenes

Acute and chronic

capsules)

health tonic

(Teucrium chamaedrys

hepatitis; zone 3

L.)

necrosis; fibrosis, cirrhosis

Isabgol

Laxative

Not identified

Giant cell hepatitis (one report)

Jin Bu Huan

Sedation; analgesic

Lycopodium serratum

Anodyne tablets

Acute and chronic hepatitis; steatosis; fibrosis

Kava

Anxiety disorders

Kava-lactone

Diffuse hepatocellular necrosis; cholestatic hepatitis; isolated γglutamyl transpeptidase increase

Kombucha

Health tonic

“mushroom”

Linghzi

Multiple indications

Yeast–bacteria

Liver injury (no

aggregate (see text)

histologic studies)

Ganoderma lucidum

Acute cholestatic hepatitis

LipoKinetix

Slimming aid

? Ephedra, ? Usnic acid

Acute hepatitis, acute liver failure

Ma huang

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Slimming aid

Ephedrine

Acute hepatitis;

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exacerbates autoimmune hepatitis

Margosa oil

Health tonic

Azadirachta indica

Reye's syndrome

Mediterranean

Anti-inflammatory

Teucrium polium

Zone 3 necrosis; acute

remedy

agent

Mixed preparations:

Herbal tonics

liver failure; fibrosis

Not identified; ?

Liver injury (no

Mistletoe, skullcap,

Scutellaria

histologic studies)

valerian

Skullcap has diterpenoids (see “Germander”)

“Natural laxatives”

Cathartic

Senna, podophyllin, aloin

Liver injury (no histologic studies)

Oil of cloves

Dental pain

Eugenol

Dose-dependent hepatotoxin; zonal necrosis

Pennyroyal oil

Abortifacient;

(squawmint)

herbal drug

Pulegone metabolites

Confluent hepatocellular

Prostata

Prostatism

Saw palmetto

Hepatitis; fibrosis

Shark cartilage

Food supplement

Not identified

Abnormal liver tests (no

necrosis

histology)

Shou-wu-pian

Dizziness,

Polygonum multiflorum

premature graying

(?anthraquinones)

Acute hepatitis

of hair, liver disease

Sho-saiko-to (TJ-9)

Health tonic; viral

Scutellaria; glycyrrhizin;

Zonal/bridging necrosis;

a

hepatitis

others

fibrosis; microvesicular steatosis

Usnic acid

Slimming aid

Usnic acid

Acute liver failure

Zulu remedy

Health tonic

Callilepis laureola

Hepatic necrosis

a

TJ-9 is used in Japan and China; there are several alternative spellings, including Sho-saiko-to and

Dai-saiko-to. SOS, sinusoidal obstruction syndrome.

Jin Bu Huan Jin Bu Huan has been implicated in several cases of acute hepatitis (701). Onset of symptoms occurred after a mean of 20 weeks (range, 7 to 52). Focal hepatic necrosis with numerous eosinophils, minor lobular hepatitis with microvesicular steatosis, and bridging fibrosis have been described. Resolution occurred within 8 weeks of discontinuation, but chronic hepatitis has been reported with long-term use (702). Levo-tetrohydropalmatine, the active ingredient, is structurally similar to the hepatotoxic pyrrolizidine alkaloids (see subsequent text). Despite being banned in the United States and Canada since 1994, new cases of Jin Bu Huan toxicity continue to accrue, stressing the need for continued vigilance.

Kava Extracts of Piper methysticum have been used as a traditional ceremonial beverage (Kava, Kava Kava) in

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South Pacific countries. Elsewhere, they are dispensed by alternative medical practitioners as anxiolytics or sedatives. Over 60 cases of hepatotoxicity have been reported worldwide (703,704,705). Most reported cases have occurred in users of alcohol or acetone extracts of the herb but traditional preparations of kava, which are aqua based, have also been rarely implicated in causing liver injury (705). The frequency of Kavaassociated liver injury has been estimated at 0.24 to 0.26 per million daily doses. Many of the affected individuals are women (female-to-male ratio, 3:1). These included 11 patients with acute liver failure who required liver transplantation (704); the explants showed panacinar necrosis. In less severe cases, cholestatic or lobular hepatitis was noted. Symptoms of liver injury were reported to begin 3 to 16 weeks after starting ingestion (range, 2 weeks to 2 years; median 4.5 months). Reversible increase in GGTP level has also been recorded in Kava users (705), but this appears unrelated to the marked rise in AT level seen in patients developing liver injury and could instead reflect adaptation (microsomal enzyme induction). The hepatotoxic potential of Kava has been disputed by phytomedicine practitioners, who cite its safe track record, and also by the presence of alcohol or concurrent hepatotoxic medications in some reports. However, there are well-documented cases occurring in the absence of such confounding factors. Moreover, positive rechallenge has been documented in at least two cases (703). The active ingredients in kava are collectively termed kava pyrones (or kavalactones). The mechanism of liver injury is unclear but the following have been suggested: Inhibition of CYP enzymes, inhibition of cyclooxygenases COX-1 and COX-2, or depletion of hepatic GSH (706). An immunoallergic basis has been postulated because of the lack of dose dependency; it is further supported by the presence of autoantibodies, eosinophilia, positive lymphocyte transformation test, and also the successful use of corticosteroids in some cases. However, metabolic idiosyncrasy appears more plausible as the above “immune” phenomena are lacking in most cases (703). As noted above, the debrisoquine slow-metabolizer phenotype may predispose to Kava hepatitis in whites. However, studies involving affected Pacific islanders have not confirmed such a relationship (705), which is not surprising given the low prevalence (approximately 1%) of CYP 2D6 deficiency in these ethnic groups (706).

Pyrrolizidine alkaloids Ingestion of these plant alkaloids is endemic in Africa (707) and Jamaica, usually as herbal tea mixtures, decoctions, or even as an enema (692). Such preparations have been associated with hepatic VOD (SOS), fibrosis, and cirrhosis. Pyrrolizidine alkaloid contamination has also been found in cases of SOS associated P.985 with consumption of Chinese herbal teas and comfrey (97,693). In India and Afghanistan, epidemics of SOS have occurred after the contamination of wheat flour with pyrrolizidine alkaloids (708). In the acute form of SOS, the typical manifestations are abdominal pain, ascites, hepatomegaly, and raised AT levels. Liver failure can occur, even during the acute phase, but recovery is also possible. On the other hand, the prognosis is poor for individuals presenting with the chronic form of this disease; death occurs from liver failure.

Herbal slimming aids Several cases of acute liver injury have been reported in association with herbal weight reduction remedies (709,710,711,712,713). In Japan, 12 women presented with jaundice, fatigue, diarrhea, and a biochemical picture of hepatocellular injury, 5 to 45 days after commencing Chaso or Onshido (709). Of these, two developed acute liver failure; one survived after a liver transplantation and the other died 6 weeks after admission. Pathologic findings were of massive or submassive hepatic necrosis or acute hepatitis. Over 400 cases of hepatotoxicity associated with herbal weight-loss aids were reported to the Japanese Health Ministry in 2002; Chaso and Onshido use were recorded in 21 and 135 cases, respectively. N-Nitrosofenfluramine has been identified as a potential hepatotoxin with these two products; it is a recognized hepatocarcinogen. Other N-nitrosofenfluramine–containing compounds associated with liver toxicity include Sennomotokounou and LipoKinetix (710) (see subsequent text). Over 100 cases, including 2 deaths from Sennomotokounou liver toxicity were reported to the Japanese Ministry of Health, Labour, and Welfare (713). Individual susceptibility may be important because the frequency of liver injury appears to be low; the CYP 2C19 poor-metabolizer phenotype was present in one of two patients with acute hepatitis. An immunoallergic basis was postulated for the other patient, who lacked this phenotype, but developed peripheral and tissue (liver) eosinophilia. LipoKinetix, a dietary supplement, has been implicated in seven cases of acute hepatocellular injury in Los Angeles (710). Five of these were Japanese nationals. Onset of liver injury was within 3 months of ingestion (many within 1 month). Three patients developed acute liver failure but eventually recovered. Recovery was complete within 3 months. Liver histology was not available. The toxic ingredient was not identified in this multicomponent herbal product; potential candidates include ephedra alkaloids or usnic acid. The latter, marketed as a “fat burner,” works by uncoupling oxidative phosphorylation. It has been implicated in causing acute liver failure in a 35-year-old woman (712). The disruption in mitochondrial bioenergetics and generation of oxidative stress could be central to usnic acid hepatotoxicity. Interestingly, usnic acid is also present in Kombucha “mushroom,” a multipurpose tonic previously implicated in cases of hepatocellular injury (685). It has also been suggested that usnic acid could be the primary hepatotoxin in LipoKinetix-related liver toxicity. However, the absence of lactic acidosis argues against the involvement of usnic acid, a primary mitochondrial toxin (710).

Natural and Synthetic Retinoids

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Hypervitaminosis A Risk factors Vitamin A is a dose-dependent hepatotoxin. Historically, cases of acute hypervitaminosis A with liver injury occurred among Arctic travelers who were forced to consume large quantities of polar bear liver. Today, liver injury more often follows self-medication with vitamin A preparations, although rare instances of hypervitaminosis A occur after consumption of large amounts of raw liver alone or in combination with βcarotene–rich vitamins (714,715). Hepatic injury occurs both with acute ingestion of massive doses (>600,000 IU) and with prolonged ingestion of smaller doses (716). The mean daily dose of vitamin A in reported cases has been 96,000 IU, and the average duration of ingestion has been 7.2 years (range 11 days to 30 years), representing a mean cumulative dose of 229 million units (717). Cirrhosis has occurred in persons with a daily intake of 25,000 IU for 6 years or longer (717). It is therefore noted that up to 3% of vitamin supplements in the United States that are recommended for daily use contain 25,000 IU or more of vitamin A (716). In patients with renal failure, vitamin A dosages as low as 4,000 IU/day can lead to hepatotoxicity (718).

Diagnosis: Presentation, clinical features, and laboratory findings In a Belgian series, only about a third of 41 cases were correctly identified at presentation; the average delay in diagnosis was 18 months (719). Hypervitaminosis A is associated with hepatotoxicity in approximately 50% of cases; other features of hypervitaminosis are usually present, such as fatigue, myalgia, bone pain, dry skin, alopecia, gingivitis, xanthosis, headache, neuropsychiatric disturbances, hypercalcemia, and growth retardation (663). The liver is often enlarged. Splenomegaly, ascites, and signs of portal hypertension are present in severe cases, but jaundice is not usually found (717). The clinicopathologic spectrum of hypervitaminosis A–related liver disease includes minor alteration of liver enzymes, peliosis hepatis (720), noncirrhotic portal hypertension with perisinusoidal fibrosis, sclerosis of central veins, and cirrhosis. Decompensated chronic P.986 liver disease can occur in the absence of cirrhosis and may be irreversible. Liver enzyme changes are nonspecific. Hypoalbuminemia, prolongation of prothrombin time, and hyperglobulinemia (with predominant IgM) are seen in advanced cases (717). Increased plasma level of retinyl esters (>10%) as a proportion of total serum vitamin A level (normal Table of Contents > Volume 2 > Section VI - Alcohol and Drug-Induced Disease > Chapter 34 - Mechanisms of Drug-Induced Liver Injury

Chapter 34 Mechanisms of Drug-Induced Liver Injury Paul B. Watkins

Key Concepts z

Most drug-induced liver injury appears to be caused by the formation of reactive metabolites from the parent drug.

z

The initiating event in liver injury is often the accumulation of a reactive metabolite over a “threshold,” which occurs when the rate at which the reactive metabolite is produced exceeds the rate at which it can be safely eliminated.

z

Reactive metabolites can injure cells in many ways, including creating “oxidative stress” and “covalent binding,” which may inhibit functioning of critical proteins or create neoantigens, stimulating an immune attack on the liver.

z

The innate immune system is involved in events that kill drug-injured hepatocytes that would otherwise survive; whether a drug-injured hepatocyte dies or recovers is largely based on a balance of multiple factors that favor cell killing or cell survival.

z

The liver can often adapt to low levels of liver toxicity through mechanisms that involve altered regulation of glutathione, enzymes, and transporters.

z

The mechanisms common to both predictable and idiosyncratic toxicity are generally not known and can probably only be identified by studying patients who actually experienced idiosyncratic toxicity.

Drug-induced liver injury has been traditionally divided into two categories: Predictable and unpredictable (or “idiosyncratic”). Predictable liver toxins produce dose-dependent injury; essentially all patients will develop liver injury if they receive a sufficiently high dose. Drugs that are predictable toxins are generally identified in preclinical (animal) studies or during the early clinical trials specifically designed to look for dose-related toxicity. If liver toxicity occurs at doses likely to be near those required for significant therapeutic benefit, the drug is generally abandoned from further development. As a result, there are few predictable hepatotoxins in

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therapeutic use today. One example of a drug that is a predictable hepatotoxin is acetaminophen. As with all predictable toxins, subtoxic exposures can generally be safely tolerated because “the dose makes the poison.” In contrast to predictable toxicity, idiosyncratic toxicity is not clearly dose related. With a true idiosyncratic toxin, only a very small fraction of the patients are susceptible to liver injury, even when receiving high doses (i.e., it is the host that makes the poison). Animal models, although having value in identifying predictable liver toxins in man, are generally of little help in identifying drugs capable of causing idiosyncratic toxicity. If the toxicity occurs in less than 1 in 1,000 patients receiving the drug, it might not be recognized during preapproval clinical trials and become evident only after regulatory approval and widespread usage. Recognition that an otherwise good drug can cause idiosyncratic hepatotoxicity often leads to regulatory P.1006 actions that limit access of patients to that drug, even when most patients are at no risk for toxicity. Idiosyncratic hepatotoxicity has been the major reason for regulatory actions concerning drugs, including failure to approve, marketing restrictions, and withdrawal from the market place (1). Idiosyncratic hepatotoxicity, therefore, poses a great problem for physicians, patients, and the pharmaceutical industry. Until the mechanisms underlying idiosyncratic hepatotoxicity are identified, it is unlikely that the industry will be able to design this liability out of new drugs. The vast majority of research on the mechanisms underlying druginduced liver injury has involved predictable hepatotoxins, particularly acetaminophen. Furthermore, it is generally assumed that the mechanisms underlying predictable toxicity are relevant to idiosyncratic toxicity, but that the latter occurs because of genetic or nongenetic factors that are present only in the susceptible patients.

Mechanisms of Predictable Hepatotoxicity Most predictable hepatotoxins, including environmental compounds such as aflatoxin B1, bromobenzene, and carbon tetrachloride, are relatively harmless to the liver. Predictable toxicity generally results from reactive, or toxic, metabolites generated from the parent (or “protoxin”) in the liver (2,3,4,5). Formation of the reactive metabolite is generally thought of as an essential step in the cascade of events leading to hepatocyte injury. A general scheme for hepatotoxicity mechanisms involving reactive metabolites is shown in Figure 34.1. The liver is particularly susceptible to generating reactive metabolites because it is the major organ responsible for drug metabolism and elimination. Furthermore, many of the same enzymes involved in the safe elimination of drugs (nontoxic pathways) have also been implicated in creating reactive and potentially toxic metabolites. When a reactive metabolite is involved in toxicity, it usually represents only a small fraction of the total metabolism of the drug. Hepatocytes are generally capable of efficiently detoxifying and eliminating reactive

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metabolites once they are formed, thereby preventing toxicity. A generally held concept is that the initiating event is the accumulation of the reactive metabolite above some threshold. Accumulation occurs when the relative rates of production of the reactive metabolite exceeds its rate of safe removal. The rate of production of a reactive metabolite in the hepatocyte reflects the intrinsic activity of the enzyme responsible for this conversion (termed bioactivation in Fig. 34.1) and the concentration of parent molecule surrounding the enzyme within the hepatocyte. The concentration of the parent molecule at the enzyme chiefly reflects (i) the competing rates of uptake into, and efflux out of, the hepatocyte and (ii) the rate of conversion of the parent molecule to safe and readily excreted metabolites (the competing safe pathways are shown in Fig. 34.1).

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▪ Figure 34.1 Central role of reactive metabolites in drug-induced liver injury. For most drugs, the major routes of elimination involve production of metabolites that are safely excreted and represent no threat to the liver cell because they are readily and safely excreted. Drugs that produce liver injury generally appear to do so through “bioactivation” to form reactive or toxic metabolites, which often result from relatively minor metabolic pathways. Fortunately, the liver generally has adequate ability to detoxify these metabolites, allowing their safe elimination. However, under certain circumstances, the reactive metabolite can accumulate in the hepatocyte above a threshold level for toxicity, resulting in hepatocyte damage through a variety of mechanisms discussed in the text. For a given level of hepatocyte injury, the outcome may be complete recovery or progression to death, depending on the response of the innate immune system.

Safe Pathways of Drug Metabolism and Transport The rates of uptake and efflux of drugs (and metabolites) probably reflect largely the activities of specific transport proteins and not passive diffusion, as previously thought. There has been great progress in the identification and characterization of these transporters (Figs. 34.2 and 34.3). Uptake transporters are present on the basolateral membrane of the hepatocyte and efflux transporters are present on both the basolateral and canalicular membranes (6,7,8,9). Once inside the hepatocyte, the rate of conversion of the parent molecule to nontoxic metabolites reflects the activities of a variety of enzymes traditionally divided into two categories: Phase 1 or Phase 2. Phase 1 reactions result in a direct modification of the

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primary structure of the drug, usually resulting in insertion of an oxygen atom in the form of a hydroxyl (–OH) group. Phase 2 reactions involve covalent binding (conjugation) of the drug to polar ligands, usually glucuronic acid or sulfate, often to the hydroxyl group resulting from Phase 1 P.1007 P.1008 metabolism. The terms Phase 1 and Phase 2 refer to the fact that often, but not always, drugs must first be subjected to Phase 1 metabolism before they can be conjugated. Metabolites generated by Phase 1 and Phase 2 enzymes are generally secreted actively into bile or back into systemic circulation for elimination in the urine by the kidneys. In most instances, this appears to reflect active transport by at least many of the same proteins involved in the efflux of parent drugs (Figs. 34.2 and 34.3). Active efflux of metabolites from the hepatocyte is sometimes termed Phase 3.

▪ Figure 34.2 Basolateral uptake and efflux transporters in the hepatocyte. Uptake of serum bile acids results from the action of sodium taurocholate cotransporting polypeptide (NTCP) and, to a lesser extent, organic anion transporting polypeptides (OATPs), which are also involved in uptake of many drugs. Multidrug resistance proteins (MRPs) are chiefly involved in the efflux of drugs and their metabolites, particularly glucuronide and sulfate conjugates. During the recovery phase of hepatotoxicity, due to acetaminophen or carbon tetrachloride, there is downregulation of NTCP and several OATPs, and upregulation of several MRPs, including MRP3 and MRP4. The aggregate effect of these changes, which would reduce the hepatocyte content of potentially injurious bile acids and xenobiotics, likely account in part for the adaptation to hepatotoxicity with recurrent dosing. OAT, organic anion transporter; OCT, organic cation transporter; OATP,

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organic anion transporting polypeptide; TC, taurocholate; OA - , organic anion; OC + , organic cation; ATP, adenosine-5'-triphosphate; cAMP, cyclic adenosine-3',5'-monophosphate; cGMP, cyclic guanosine-3',5'monophosphate; MTX, methotrexate. (Adapted from Chandra P, Brouwer KL. The complexities of hepatic drug transport: current knowledge and emerging concepts. Pharm Res 2004;21(5):719–735.)

▪ Figure 34.3 Canalicular efflux transporters in the hepatocyte. Bile salt excretory protein (BSEP) is the major bile acid efflux pump. Multidrug resistance-1 (MDR1) and multidrug resistance protein-2 (MRP2) are responsible for biliary excretion of most xenobiotics and their metabolites. During the recovery phase of hepatotoxicity, due to acetaminophen or carbon tetrachloride, there is upregulation of MRP2 and probably MDR1 and bile salt export pump (BSEP). These changes complement the altered regulation in basolateral transporters (Fig. 34.2) and further reduce hepatocyte content of potentially injurious bile acids and xenobiotics, thereby contributing to adaptation with recurrent dosing. OA - , organic anion; ATP, adenosine-5'-triphosphate; MTX, methotrexate; BCRP, breast cancer resistance protein; OC + , organic cation; TC, tauricholate. (Adapted from Chandra P, Brouwer KL. The complexities of hepatic drug transport: current knowledge and emerging concepts. Pharm Res 2004;21(5):719–735.)

Phase 1 It is now appreciated that most (but not all) of what was described as Phase 1 drug metabolism is the result of the activity of a large family of enzymes termed cytochromes P-450, now termed simply P-450s or CYPs (pronounced “sips”). Liver P-450s metabolize most drugs in use today; in many and perhaps most instances, metabolism by a P-450 is the rate-

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limiting step in the elimination of the parent drug. There are relatively few P-450s important for drug metabolism (10,11), and these derive from three gene families, now termed CYP1, CYP2, and CYP3 (12). Within each P-450 family, there are subfamilies designated by capital letters. Each subfamily generally contains multiple members, designated by Arabic numbers usually reflecting the order in which they were discovered.

Table 34.1. Characteristics Of Major Human Liver P-450S

P-450 CYP 1A2

Substrates

Inhibitors

Inducers

Tacrine Theophylline

Fluvoxamine Cimetidine

Cigarette smoke

Tolcapone a (13) Dihydralazine a (14)

Ciprofloxacin

Charcoalbroiled foods Omeprazole

CYP 2A6

Acetaminophen a (15)

8Methoxypsoralen

None known

Halothane a (16) Nicotine

CYP 2B6

Bupropion Carbamazepine a (17)

None known

Rif, phen, carb, pheno, SJW

CYP

Paclitaxel

None known

Rif, phen,

2C8

Rosiglitazone

carb, pheno, SJW

CYP

Diclofenac a (18)

2C9

Warfarin Tienilic acid a (19)

Fluvoxamine

Rif, phen, carb, pheno, SJW

Phenytoin

CYP

Omeprazole

Sulfinpyrazone

None

2C19

Mephenytoin Diazepam

Ticlopidine Fluvoxamine

identified

Phenytoin a (20)

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CYP

Debrisoquine

Fluoxetine and

None

2D6

Dextromethorphan

other selective

identified

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Metoprolol and other

serotonin

β-blockers

reuptake

Perhexiline

inhibitors

Amitriptyline and

Quinidine

other neuroleptics Encainide Codeine

CYP

Acetaminophen a

Disulfiram

Ethanol

2E1

Ethanol

Ethanol

Isoniazid

Erythromycin Cyclosporin A

Ketoconazole and other azoles

Rif, phen, carb,

Carbamazepine a

Troleandomycin Ritonavir

pheno, SJW

Tolcapone a (13) Isoniazid a (21) Halothane (16)

CYP 3A4

(17) Midazolam/triazolam Lovastatin and other statins Saquinavir and other protease inhibitors Trazodone a (22) Nefazodone a (23) Troglitazone a (24)

a

Drugs are metabolized to the reactive metabolites implicated in hepatotoxicity. Rif, rifampin; phen, phenytoin, carb, carbamazepine; phenol, phenobarbital; SJW, Saint John's Wort.

A list of the major P-450s involved in human drug metabolism is shown in Table 34.1. In many instances, a single P-450 represents the major pathway of P.1009 metabolism of a drug. Many pharmaceutical companies now use highthroughput technology to identify the P-450s that metabolize compounds in development and use this information to select lead candidates for further development (25,26,27).

Phase 2 The best-studied Phase 2 enzymes involved in the elimination of nontoxic metabolites are uridine-5′-diphosphate (UDP) glucuronyltransferases and

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sulfotransferases, which catalyze conjugation to glucuronic acid and sulfate, respectively. Conjugation generally results in enhanced water solubility and elimination in urine and stool. As with the P-450s, the UDP glucuronyltransferases (UGTs) and sulfotransferases arise from multigene families (28–30). The sulfotransferases are divided into five gene families, whereas the UGTs are divided into two gene families termed UGT1 and UGT2. The UGT1 family contains eight enzymes (designated by Arabic numerals) and the UGT2 family contains seven enzymes. There appears to be considerable catalytic specificity of UGTs toward drugs, although such characterization is progressing relatively slowly. One problem has been that unlike P-450s, it has proved challenging to reconstitute the activity of UGTs in robust, in vitro systems.

Enzymes Involved in Generating Reactive Metabolites It appears that the initiating step in drug-induced liver injury often involves creation of a reactive metabolite from the parent molecule in the liver (Fig. 34.1). Reactive metabolites are generally minor products of drug metabolism, and their reactivity can make them very short lived and difficult to detect in biologic systems. For this reason, identifying the precise structure of a reactive metabolite can be challenging. P-450s are the major enzymes capable of generating reactive and potentially toxic metabolites. The identical enzymes involved in the safe metabolism of drugs are those that have been most implicated in the production of hepatotoxic metabolites (see Table 34.1 for examples). In general, P-450s are expressed in highest concentration in zone 3 hepatocytes, and this in part accounts for the predominance of pericentral (zone 3) necrosis in some forms of drug-induced liver injury (such as that due to acetaminophen) (31). Interspecies differences in P-450 catalytic activity and regulation probably contribute to the imperfect ability of preclinical animal studies to identify human hepatotoxins (32). Several methods have been used to determine the P-450s responsible for the production of toxic metabolites. For example, if an antibody or chemical that specifically inhibits a certain P-450 causes significant reduction in the production of the reactive metabolite in liver extracts, it is assumed that this P-450 is involved (33). In some instances, it is possible to use selective P-450 inhibitors to identify the responsible P-450s in clinical studies. This strategy is suggested by the listing of specific inhibitors in Table 34.1. For example, acetaminophen is believed to cause toxicity in the liver because of the production of the metabolite N-acetyl-p-benzoquinone imine (NAPQI). The total production of NAPQI from an oral dose of acetaminophen can be estimated from the production of thiol metabolites, which are eliminated in urine. When healthy volunteers were given a dose of acetaminophen together with a CYP 2E1 selective inhibitor (disulfiram), the urinary production of NAPQI derivatives fell to an average of 69% (15), indicating a major role for CYP 2E1 in the production of this metabolite. In contrast, treatment with rifampin, which would induce multiple other P450s (Table 34.1), did not increase urinary elimination of the thiol

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metabolites (15). Similar clinical research has been done with halothane. Severe halothane liver toxicity is thought to result from a trifluoroacetyl intermediate, which in turn leads to measurable levels of trifluoroacetyl acid (TFA) in plasma and urine (34). Plasma and urine levels of TFA fell 70% when patients receiving halothane anesthesia were pretreated with the CYP 2E1 inhibitor disulfiram (35). A small reduction in TFA production was also observed when these patients were pretreated with the CYP 2A6 inhibitor 8methoxsalen, but no change was observed after treatment with triacetyloleandomycin (TAO), a potent inhibitor of CYP 3A4 (16). These studies indicate that the major enzyme involved in the production of the trifluoroacetyl intermediate from halothane in vivo is CYP 2E1, with a minor contribution from CYP 2A6 and no contribution from CYP 3A4. Not all reactive metabolites are produced by P-450s. Some reactive metabolites, such as acylglucuronides (36), are products of Phase 2 metabolism. For example, glucuronide metabolites of diclofenac and valproic acid have been shown to covalently bind multiple proteins in the hepatocyte, and this covalent binding may contribute to the hepatoxicity rarely associated with these drugs (37,38).

Enzymes Involved in the Safe Elimination of Reactive Metabolites Minor reactive metabolites are probably produced commonly during the metabolism of drugs. Fortunately, the liver generally has the ability to dispose of these P.1010 metabolites before they can cause injury. The major safe elimination pathway for reactive metabolites involves conjugation to glutathione (GSH). Although GSH is synthesized in every cell in the body, the liver is the major site of its synthesis. Under usual conditions, the hepatocyte cytosolic concentration of GSH is quite high (approximately 10 mM). GSH may conjugate to reactive metabolites spontaneously, but this reaction is usually catalyzed by the glutathione-S-transferases (GSTs) (39). The resultant conjugates are generally nonreactive and readily excreted into bile or urine. GSH conjugates are pumped from the liver cell into bile by transporters, particularly multidrug resistance protein-2 (MRP2) (Fig. 34.3). There are three families of GSTs: Cytosolic, mitochondrial, and microsomal. The cytosolic GSTs are those most involved in drug metabolism and are divided into seven classes, designated α, µ, π, σ, θ, ω, and ζ (40). Each family has several members designated by Arabic numbers. For example, GSTM1 is the first of the five members of the µ gene family. The important role of GSH conjugation has led some industry scientists to develop sophisticated methods to detect GSH conjugates in liver microsomes and whole animals (41) as an initial means of detecting reactive metabolites. However, GSH conjugates can enter bile and not be detected in whole animal studies. In addition, not all reactive metabolites depend on GSH for safe elimination. One important class of reactive

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metabolites is epoxides, which can be safely eliminated through the action of microsomal epoxide hydrolase (42). There appears to be just one gene encoding this enzyme in humans.

How the Reactive Metabolites Cause Hepatotoxicity There appear to be many potential ways by which toxic metabolites can injure the liver cells, but the most common mechanisms appear to involve covalent binding and oxidative stress. A critical target to reactive metabolites appears to be mitochondria.

Covalent Binding A variety of experimental evidence supports the view that covalent binding of reactive metabolites to proteins can alter their function, contributing to, or causing, hepatotoxicity (5,43,44). For example, the location of covalently bound protein adducts within the acinus correlates well with the location of hepatocyte damage due to acetaminophen (45) and cocaine (46). In addition, experimental manipulations that increase or decrease the rate of covalent binding (e.g., treatment with inducers or inhibitors of specific P-450s) proportionately increase or decrease the sensitivity of the liver to toxicity (46,47,48). However, the simple magnitude of covalent binding produced by a drug does not accurately predict hepatotoxicity (37,44). For example, there exist structural analogs of acetaminophen that have relatively little hepatotoxic potential but nonetheless covalently bind to hepatic proteins at rates comparable to, or actually higher than, that observed with acetaminophen (49). In addition, under certain experimental conditions, hepatocyte injury produced by cocaine can be prevented without influencing the extent of covalent binding to hepatocyte proteins (50). It has, therefore, become clear that covalent binding to protein does not always result in toxicity. Indeed, covalent binding may in some instances represent an adaptive mechanism for the cell. For example, it has been speculated that certain cytosolic proteins identified as targets for acetaminophen covalent binding may function to protect the cell by inactivating reactive metabolites (51). In view of the discrepancies between total covalent binding and toxicity, the idea that toxicity is caused by covalent binding to specific proteins critical to cell viability has emerged. During acetaminophen hepatotoxicity, multiple enzymes important to the hepatocyte undergo covalent modification that results in loss of catalytic activity (5). The identity of specific proteins targeted by a given metabolite probably reflects several factors. First, if the metabolite is extremely reactive, it is likely to be short lived; hence, binding can only occur to proteins that are located in close proximity to the enzyme that produced the metabolite. The closest protein to the metabolite when it is created is the enzyme that produced it; hence, when a specific P-450 is identified as the target for covalent binding, it is likely that this is the enzyme responsible for the generation of the reactive metabolite (52). If the implicated metabolite is less reactive and longer lived, it may diffuse from the site where it was formed to bind to more

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distant proteins. Which specific proteins are affected also reflects the chemical nature of the metabolite and target protein. Acetaminophen and the structurally similar but not hepatotoxic compound N-acetyl-maminophenol (AMAP) produce comparable amounts of total covalent binding in the liver (49). However, covalent binding with acetaminophen occurs largely in mitochondria, whereas AMAP forms adducts predominantly in other cellular compartments (53). Specific binding to critical mitochondrial proteins may therefore account for the differences in hepatotoxic potential of acetaminophen and AMAP.

Oxidative Stress The liver is the largest solid organ in the body, and its numerous metabolic functions require substantial P.1011 energy. Energy is largely provided by adenosine-5′-triphosphate (ATP), which is derived from the reduction of molecular oxygen to water. This process, termed oxidative phosphorylation, occurs in mitochondria. In the process of generating ATP and water, up to 5% of oxygen is converted to superoxide anion (O 2 - ) and its metabolites, which are collectively termed reactive oxygen species (ROS). ROS can also be produced outside of the mitochondria as a by-product of oxidative metabolism by cytochromes P450, particularly CYP 2E1 (54) and CYP 3A4 (55). ROS can be harmful to cells because they can react with proteins, deoxyribonucleic acid (DNA), or lipids, causing cell damage or death (56,57). For example, ROS can initiate lipid peroxidation. This is a self-propagating chain reaction in which unsaturated fatty acids of the membranes are broken down to volatile small molecules (e.g., F2-isoprostanes) that can be measured in the breath (58). ROS usually do not accumulate in hepatocytes because there exist multiple mechanisms for their deactivation to less harmful species. Moreover, when ROS begin to accumulate, the cell mounts a coordinated “antioxidant response.” This involves activation of NFR2 that mediates transcriptional activation of a cassette of genes that include those coding for glutathione synthesis and glutathione transferases, as well as certain UGTs. (59). The term oxidative stress has been used for the situation in which production of ROS exceeds the capabilities of antioxidant defenses, resulting in accumulation of ROS and oxidative damage to the cell (56). Oxidative stress can result in programmed cell death (apoptosis) in addition to necrosis (60).

The Role of Mitochondria as a Target for Reactive Metabolites The mitochondria are the cell's major source of energy (ATP). With complete loss of functioning of mitochondria, the ATP-dependent Na + /K + ion pumps at the plasma membrane cease to function, and the hepatocyte swells and ruptures in a process known as necrosis. Programmed cell death, or apoptosis, requires energy, and therefore, some mitochondrial function is required.

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Loss of mitochondrial function could theoretically result from covalent binding of a reactive metabolite to key proteins involved in the maintenance of the mitochondria or from damage to mitochondrial DNA (61). Most mitochondrial proteins are encoded by genes present in the cell nucleus; however, some vital mitochondrial proteins involved in the oxidative phosphorylation are the products of mitochondrial genes. Mitochondria are relatively deficient in DNA repair enzymes, and hence DNA mutations caused by reactive metabolites (or resulting from oxidative stress) can have a greater effect on mitochondria than on other cellular organelles. For example, some antiviral drugs (e.g., fialuridine [FIAU] and azidothymidine [AZT]) are believed to have caused liver failure because of drug-induced mutations in mitochondrial genes (62,63). Mitochondrial dysfunction can also occur as a consequence of depletion of mitochondrial GSH (64). Mitochondria are particularly susceptible to GSH depletion because they do not synthesize GSH and it must be imported from the cytosol. Mitochondria also lack catalase, and therefore rely more on glutathione peroxidase to handle ROS. The activity of glutathione peroxidase is critically dependent on the concentration of GSH within the mitochondria, with a rapid fall in activity as GSH concentrations (usually 10 to 15 mmol) fall below 2 to 3 mmol. More than 90% depletion of mitochondrial GSH therefore significantly impairs the mitochondria's ability to safely dispose of ROS. Because ROS are constantly produced in mitochondria, even in totally healthy hepatocytes, depletion of mitochondrial GSH by reactive metabolites may be sufficient to cause oxidative stress. Because the mitochondria are the preferred targets for NAPQI, which readily binds GSH, depletion of mitochondrial GSH is believed to be a mechanism for acetaminophen hepatotoxicity. Mitochondria play a central role in apoptosis. This may reflect the notion that mitochondria evolved from a primitive bacterium that, when an oxygen atmosphere began to emerge, entered and became part of early eukaryotic cells (65). The bacterium's rudimentary machinery for oxidative phosphorylation provided the eukaryote with a means for survival in what would have otherwise been a toxic environment. The bacterium also probably benefited in most instances from the controlled environment afforded by the host cell. It has been theorized that the bacterium retained or developed the ability to kill the cell and thereby “go it alone” (66). According to this theory, as the bacteria evolved to become permanent residents in cells (i.e., mitochondria), the death mechanisms remained. The mechanisms by which mitochondria initiate apoptosis have been largely clarified. The critical event appears to be depolarization of the inner membrane of the mitochondria, termed mitochondrial permeability transition (MTP), which results from opening of pores (67). MTP results in loss of the proton gradient required for generation of ATP. If all mitochondria are affected, necrosis will result. However, an immediate effect of MTP pore opening is the swelling of mitochondria and eventual rupture of the outer mitochondrial membrane. When mitochondria rupture, cytochrome c is released, and this causes activation of cytosolic caspases that initiate apoptosis. Evidence suggests that MTP may be a common

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pathway for hepatocyte apoptosis resulting from diverse signals that may be involved in some forms of hepatotoxicity, including ligand binding to P.1012 plasma membrane death receptors (Fas and tumor necrosis factor receptor [TNFR]), release of calcium from the endoplasmic reticulum, and release of lysosomal enzymes (68). Apoptosis requires ATP; hence the energy status of the hepatotomy (i.e., how many mitochondria remain functional) appears to determine whether death will be by apoptosis or necrosis. Features of both necrosis and apoptosis can be present in a dying hepatocyte, termed necrapoptosis (69).

Progression versus Recovery Once liver injury has begun, it can either progress to liver failure or can subside with recovery (Fig. 34.1). It was originally assumed that the critical variable here was how much damage was done by the reactive metabolite, such as the extent of critical covalent binding or extent of oxidative stress. Although this is an important variable, it has recently become clear that there are many factors that can influence the outcome that are “downstream” of the events discussed so far. These factors speed the death of injured or dying cells. Many of these factors are components of the “innate immune system” (70). The innate immune response, unlike the acquired immune response, is not antigen specific, has no memory, and can be immediately activated to attack pathogens. It is the coordinated and rapid release of certain cytokines and other biologic mediators that neutralize pathogens and, together with natural killer T cells and tissue macrophages, kill infected cells. The innate immune response is beneficial if it limits the spread of infection. The drug-injured hepatocyte may appear as an infected cell to the innate immune system. In this case, however, the innate immune system may not be beneficial because hepatocytes that would otherwise recover are killed. This has been most clearly shown with acetaminophen in which elimination of various components of the innate immune system reduce susceptibility to acetaminophen hepatotoxicity in rodents (71). Examples of factors that increase susceptibility to acetaminophen hepatotoxicity include interferon-γ (72), macrophage inhibitory factor (MIF) (73), and TNF (74). Factors that counteract the innate immune response are also prominent in the liver (71,75). This may reflect the fact that the liver's drug metabolizing machinery probably evolved to handle natural substances, such as natural insecticides made by edible plants or fungal products of food spoilage. Reactive metabolites are generated in the liver by many of these natural “xenobiotics,” and this can result in liver injury. In this situation, as with drugs, it is probably not desirable to kill the otherwise viable hepatocytes. A reasonable hypothesis is that factors counteracting the innate immune response evolved in the liver to limit needless hepatocyte killing. Data suggest that Kupffer cells may be important in reducing response to liver toxicity (75). Cytokines that reduce susceptibility to acetaminophen hepatotoxicity include interleukin-10 (IL-10) (76) and IL-

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6 (77). Other issues that may determine whether liver injury progresses or regresses have been identified. Soluble factors released from dying hepatocytes (e.g., calpain) (78) may kill adjacent healthy hepatocytes. In addition, it has been shown that liver injury caused by one predictable toxin can be “amplified” by pretreatments that hinder the liver's ability to regenerate (79). Although most studies of acetaminophen hepatotoxicity involve single toxic doses, recurrent dosing has been shown in rodents to greatly reduce susceptibility to subsequent otherwise toxic doses. In addition, mice treated with certain halogenated hydrocarbons develop hepatic necrosis after 1 week of treatment, but the liver injury largely resolves with continued exposure (80). This indicates that the liver can adapt in the face of true hepatotoxicity, with resolution of the injury despite continued exposure to the offending agent. This is reminiscent of transient elevations in the level of alanine aminotransferase (ALT) that reverse with continued exposure to drugs that can cause progressive liver injury (e.g., isoniazid) (1). In addition, this adaptation phenomenon may account for rare reports of narcotic/acetaminophen abusers consuming up to 65 g of acetaminophen daily without evidence of significant liver injury (81). Adaptation to hepatotoxicity appears to involve altered regulation of the genes involved in determining reactive metabolite accumulation. For example, there is downregulation of the P-450s involved in producing NAPQI and increase in the hepatocyte content of GSH when rodents are exposed to increasing doses of acetaminophen (81). In addition, it has been shown that during the recovery phase of the acute exposure to acetaminophen or carbon tetrachloride, there is downregulation of certain basolateral uptake transporters (sodium taurocholate cotransporting polypeptide [NTCP] and several organic anion transporting polypeptides [OATPs]) and upregulation of basolateral and canalicular efflux transporters (including MRP3, MRP4, and MRP2) (82,83,84). This appears to protect the cell by preventing uptake and accelerating removal of xenobiotics and potentially toxic bile acids. These effects could result from a combination of the antioxidant response and the acute phase reaction chiefly mediated by Nrf-2 activation and IL-6, respectively (85,86). In addition, regenerating hepatocytes have reduced P-450 activity and increased GSH levels (87). A human study suggested upregulation of the several transporters, including multidrug resistance-1 P.1013 (MDR1), in hepatocytes remaining after subfulminant liver injury (88).

Variation in Susceptibility to Drug-Induced Liver Injury Increased susceptibility to hepatotoxicity could occur from any of the conditions outlined in Table 34.2. To date, most studies of susceptibility to predictable toxins have focused on the drug metabolizing enzymes and transporters implicated in the accumulation of the reactive metabolite

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(89,90). For example, patients who are genetically deficient in the activities of both GSTM1 and GSTT1 appear to have increased incidence of liver injury from tacrine and valproic acid (91,92). However, significant correlation between toxicity and genetic variation, when found, appears to account for only a small fraction of susceptibility. This undoubtedly reflects the fact that accumulation of the reactive metabolite is only the initial step in the cascade of events culminating in liver injury, and each of these steps is loci for variation (Table 34.2). Another reason for the relative lack of success in linking genetic polymorphisms to susceptibility is the prominent role played by nongenetic factors. For example, some drugs or other xenobiotics either inhibit or increase (induce) the activity of certain drug metabolizing enzymes (Table 34.1) and transporters. If safe pathways are induced or bioactivation pathways are inhibited, there should be less toxicity at a given dose of predictable toxin. Alternatively, if safe pathways are inhibited and bioactivation pathways are induced, susceptibility to toxicity should increase. This could account for the enhanced hepatoxicity of certain drug combinations, such as rifampin and pyrazinamide (93). However, because induction of metabolic pathways usually involves activation of transcription factors that result in the transcription of multiple genes (94), the effects of inducers of bioactivation pathways may be offset by simultaneous induction of safe elimination pathways (32). An example where variation in susceptibility to toxicity can result from nongenetic factors is the enhanced susceptibility to acetaminophen toxicity observed in alcoholics. As previously discussed, the reactive metabolite mediating liver toxicity is NAPQI, which is produced predominantly by CYP 2E1 and is normally safely eliminated through conjugation with GSH.

Ethanol and Acetaminophen Chronic consumption of ethanol appears to increase susceptibility to acetaminophen hepatotoxicity (95). Chronic ethanol consumption can increase CYP 2E1 activity (Table 34.1), and this provides an attractive explanation for incremental risks in ethanol consumers. However, early animal (96,97) and human (98) studies did not show increases in NAPQI formation when acetaminophen was given during or immediately after ingestion of ethanol. Indeed, these studies suggested that ethanol consumption actually reduces the rate of production of NAPQI, protecting the liver from toxicity. This is explained by the observation that induction of CYP 2E1 largely involves stabilization of P.1014 the enzyme (reduced degradation) and that this occurs when ethanol is bound to the enzyme as a substrate (99,100). Prolonged intoxication, therefore, results in an accumulation of CYP 2E1, but the enzyme activity is reduced because the induced CYP 2E1 is inhibited by ethanol (Fig. 34.4). When ingestion is stopped and ethanol is cleared from the liver, the accumulated CYP 2E1 is no longer inhibited and the aggregate CYP 2E1 activity is increased above baseline levels (100). However, the stabilization against degradation is also reversed, resulting in a relatively rapid fall in

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enzyme activity to the preethanol exposure level. This results in a narrow window of susceptibility that probably last less than 24 hours (100). This effect of inhibition followed by transient induction is also mimicked by some other substrates of CYP 2E1, including isoniazid (101). This may account for reports of enhanced susceptibility to acetaminophen toxicity in patients treated with isoniazid (102,103).

Table 34.2. Some Potential Reasons for Increased Susceptibility to Predictable Hepatotoxicity

1. Decreased activity of safe elimination pathways Genetic—polymorphisms in Phase 1 and 2 enzymes, transporters Nongenetic—drug interactions involving enzyme/transporter inhibition, nutrition, inflammation 2. Increased activity of enzymes producing the reactive metabolite Genetic—gene duplication (CYP 2D6) Nongenetic—induction of P-450s 3. Reduced elimination of the reactive metabolite Genetic—polymorphisms in elimination enzymes (e.g., GSTs, EH) or transporters (e.g., MRP2) Nongenetic—drug interactions involving enzyme/transporter inhibition, nutrition, inflammation, cofactor depletion (GSH) 4. Variation in proteins and pathways targeted by reactive pathways Genetic—polymorphisms in the proteins involved in target pathways (e.g., inherited defects in oxidative phosphorylation proteins) Nongenetic—drug effects (e.g., aspirin inhibition of oxidative phosphorylation), nutrition, concomitant disease 5. Variation in the innate immune response Genetic—polymorphisms in cytokines and proteins involved in Kupffer cell and lymphocyte function Nongenetic—inflammation, nutrition 6. Variation in the ability to regenerate hepatocytes Genetic—polymorphisms in genes that are important in regeneration Nongenetic—effects of other drugs/xenobiotics, age, nutrition, inflammation 7. Variation in the ability to adapt to toxicity Genetic—polymorphisms in enzymes, transporters, and proteins involved in their regulation Nongenetic—effects of other drugs/xenobiotics, age, nutrition, inflammation

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GST, glutathione-S-transferase; EH, epoxide hydrolase; MRP, multidrug resistance protein; GSH, glutathione.

Chronic alcoholics are also likely to have reduced hepatocyte concentrations of GSH, particularly mitochondrial GSH (104), limiting the ability to safely eliminate the NAPQI once formed. Another clinical situation that appears to increase susceptibility to acetaminophen toxicity is fasting (105). This should result in reduced GSH levels but should also cause depletion of the UGT cofactor glucuronic acid, reducing the ability to eliminate acetaminophen by nontoxic pathways. It has also been suggested that liver hypoxia due to cardiopulmonary insufficiency can increase susceptibility to acetaminophen toxicity because of reduced glucuronidation capacity (106).

Relevance of Predictable Toxicity to Idiosyncratic Toxicity Understanding the processes involved in the production of liver toxicity from reactive metabolites has greatly improved the understanding of variation in susceptibility to predictable liver toxins, particularly acetaminophen. However, the toxicity observed still has the characteristics of a predictable toxin, such as early onset and dose dependence, within the individual. In addition, the injury to the liver remains pericentral (zone 3) necrosis, a characteristic of many direct hepatotoxins. In contrast, idiosyncratic toxicity generally begins after weeks or months of treatment and P.1015 typically involves a panacinar injury (1). These findings suggest fundamental differences between idiosyncratic and predictable hepatotoxicity. One fundamental difference may be the involvement of the acquired immune system.

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▪ Figure 34.4 Effect of ethanol on acetaminophen (APAP) toxicity. Acetaminophen is converted by CYP 2E1 to the reactive metabolite Nacetyl-p-benzoquinoneimine (NAPQI), which is then conjugated to glutathione and safely excreted. If production of NAPQI is rapid enough to deplete available cytosolic glutathione stores, NAPQI travels to mitochondria where it covalently binds to critical proteins and depletes mitochondrial glutathione, resulting in oxidative stress. Ethanol (ETOH) binds tightly to the substrate-binding site of CYP 2E1, preventing APAP from being metabolized to NAPQI. This accounts for the observation that acutely intoxicated rodents produce less NAPQI and are resistant to APAP toxicity. However, the intracellular half-life of CYP 2E1 is prolonged when bound to ETOH, so the enzyme accumulates in an inactive form during intoxication. When ETOH consumption is ceased and ETOH removed from the liver, the accumulated CYP 2E1 becomes fully active and the rate of NAPQI formation would be increased until the CYP 2E1 levels return to baseline (probably not more than 24 hours). This effect is modest in social drinkers but can become significant when very large amounts of ethanol are consumed for prolonged periods (100).

Immunologic Mechanisms of Hepatocyte Injury It is generally accepted that immunological mechanisms underlie the liver injury produced by some drugs (107). For example, liver injury due to halothane, phenytoin, and sulfonamides characteristically present with fever, rash, and eosinophilia, the classic clinical hallmarks of hypersensitivity (108). This type of liver injury characteristically occurs within the first month of starting therapy with the drug, similar to the time

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required to become fully immunized to a vaccine. Reexposure after an episode of toxicity generally results in more rapid onset of the toxicity and greater severity of the injury, as would be expected with a hypersensitivity reaction. There is evidence that acquired immune mechanisms may be involved in idiosyncratic hepatotoxicity even in the absence of clinical signs of hypersensitivity. For example, methyldopa-induced liver injury is not usually associated with peripheral eosinophilia, fever, or rash but recurs promptly and may be more severe on rechallenge, consistent with an immune mechanism (109). Tacrine-induced liver disease (110) also recurs promptly on rechallenge, consistent with an immunologic mechanism. However, the injury observed on rechallenge is characteristically much less severe than the original insult. The idea that the acquired immune system is involved in many forms of hepatotoxicity is also supported by lymphocyte proliferation studies. These studies are performed by isolating peripheral blood lymphocytes of patients experiencing hepatotoxicity and determining whether a subpopulation of the cells proliferate on exposure to the implicated drugs. A proliferative response implies drug stimulation of cellmediated immunity, although it is possible that this is a consequence rather than a cause of the injury. In one study (111), 56% of 95 patients with liver injury to diverse drugs demonstrated lymphocyte proliferation in response to exposure to the implicated drug. In contrast, proliferation was not observed in any of the 35 controls who had been exposed to the same drugs without evidence of liver toxicity. In 70% of the patients with a positive test result, there were no clinical signs suggestive of hypersensitivity.

Antigens stimulating the acquired immune system Patients with liver injury associated with several drugs characteristically have circulating antibodies to liver and kidney endoplasmic reticulum, termed anti–liver/kidney microsomal (LKM) antibodies (112,113). It is assumed that an acquired immune response is to a new antigen created by covalent binding between the reactive metabolite and a hepatocyte protein. Anti-LKM antibodies frequently react with P-450s (114,115,116). The current concept is that if a P-450 produces a highly reactive metabolite, the metabolite can covalently bind to, or otherwise damage, the P-450. Antibodies are formed if this altered P-450 is antigenic and gets outside the hepatocyte, from where it can be picked up by antigen-presenting cells. However, cell lysis may not be necessary for antigen recognition because P450s appear to be present in low abundance outside the liver plasma membrane (114). It should also be noted that most proteins destined for the plasma membrane are synthesized in the endoplasmic reticulum, where most reactive metabolites are produced. Covalent modification of proteins can occur in the endoplasmic reticulum before transport to the plasma membrane (117). There remains controversy over whether anti–P-450 antibodies actually mediate an immune attack on the liver because no one has yet convincingly shown that these antibodies can cause liver injury in a living animal model.

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It remains possible that the antibodies are an epiphenomenon, appearing only after the antigens are released into circulation as hepatocytes are lysed by other mechanisms. For example, it has been noted that anesthesiologists commonly have circulating antibodies to CYP 2E1 but have no evidence of liver injury (118). However, the immune system generally will not attack healthy cells just because they contain novel antigens on their surface; it has been postulated that a second “danger signal” is required (119). The nature of this signal is not known, but it is speculated that it is present in injured cells. This is consistent with the observation that vaccines only work when given with adjuvants that cause tissue injury at the site of injection. If this theory is correct, reactive metabolites may stimulate immune attack on the liver only if they cause hepatocyte injury in addition to creating neoantigens. Regardless of whether they mediate drug-induced liver injury, anti–P-450 antibodies can be employed in immunochemical techniques to identify the specific human P-450s that are involved in generating the reactive metabolite, even if the structure of the reactive metabolite is unknown. It should be noted that when the lymphocyte proliferation test result is positive, the proliferation is generally most pronounced in response to the parent drug and not to its metabolites (120). This has led to the pharmacological interaction (PI) hypothesis, which states that parent drugs can initiate an immunological reaction that leads to adverse drug reactions, including hepatotoxicity (121). P.1016

Hepatotoxicity Not Related to Reactive Metabolites Although it is generally believed that reactive metabolites are the initiating events in most forms of drug-induced liver disease, this is not always the case. For example, drugs may directly interfere with crucial hepatocyte functions, resulting in toxicity. One example of this is the interference with the homeostasis of bile acids, which can be toxic to cells, particularly to mitochondria (122). The concentration of bile acids within the hepatocyte is governed by the rates of synthesis, uptake, and efflux of bile acid, which are usually tightly regulated. If a drug interferes with this homeostasis, toxicity could result. For example, it has been demonstrated that troglitazone and bosentan inhibit the bile salt excretory protein (BSEP) (Fig. 34.2) and this may contribute to the hepatoxicity observed with these drugs (123,124,125).

The Pharmaceutical Industry and Preclinical Drug Testing Idiosyncratic hepatotoxicity is the major single reason for regulatory actions concerning drugs. Pharmaceutical companies are currently spending many millions of dollars to improve the ways by which drug candidates are screened for hepatotoxic potential. No consensus has yet been reached and practices vary.

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One approach has been to try to “humanize” preclinical testing by using cultured human hepatocytes (126) or mice that express human genes relevant to toxicity (such as human P-450s) (127). The value to these approaches is questionable because many important genes stop being expressed in cultured hepatocytes (128), it is generally not possible to maintain hepatocytes in culture for the weeks or months it characteristically takes to develop idiosyncratic toxicity, and it is statistically unlikely that the hepatocytes would have been obtained from one of the rare people actually susceptible to the toxicity. A problem with humanized mice is that we do not yet know which are the relevant genes to target. Another approach taken is to screen compounds for the ability to form reactive metabolites. The rationale is that if formation of reactive metabolites is an essential step in idiosyncratic hepatotoxicity (Fig. 34.1), understanding the many potential processes that culminate in liver injury are irrelevant if no reactive metabolite is produced (41,129,130). The simplest way to screen compounds for the potential to produce reactive metabolites is to look for a time-dependent fall in the activity of P-450s as they metabolize the drug in in vitro systems. Such a fall may indicate the formation of a reactive metabolite that is damaging the enzyme. Another more expensive approach is to use mass spectral techniques to detect GSH adducts in liver extract incubations. A more informative (but also the most expensive) method for detecting reactive metabolite formation is to radiolabel the drug and thereby track exactly what happens to it in liver extracts or whole rats (129). Covalent binding can be easily demonstrated, and identification of the reactive metabolite is also facilitated. Once identified, chemists can attempt to modify the molecule to preserve its therapeutic effect, while reducing the ability to form the reactive metabolites. One problem with attempting to screen reactive metabolite formation is that most drugs generate them to some degree, and some drugs will be discarded unnecessarily. This is a problem because reactive metabolite screening generally occurs relatively late in compound selection when there are only a few molecules from which to choose a “lead compound.” This is because methods to screen for reactive metabolites are not high throughput, although this may soon change (131). Furthermore, some mechanisms of toxicity, such as BSEP inhibition, would not be detected by this approach. Finally, there has been the broad application of current genomic technology to traditional preclinical toxicity testing (132). This technology allows simultaneous quantitation of thousands of messenger ribonucleic acids (mRNAs) (the “transcriptome”), proteins (the “proteome”), and endogenous metabolites (the “metabolome”). At least some companies have treated rats with known hepatotoxic and nontoxic drugs and examined time-dependent changes in the liver transcriptome, liver and serum proteome, and liver, serum, and urine metabolome. The goal is to find specific patterns that predict hepatotoxicity potential. Proteome and metabolome analyses have yet to become a standard part of preclinical testing. However, at least

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several companies have selected a set of mRNA transcripts that appear to correlate with certain forms of hepatotoxicity and are routinely measuring them, along with traditional serologic markers (like ALT) and pathological evaluation, in the lead candidate selection process. This technology is also being applied to cultured hepatocytes. In one study involving cultured human hepatocytes, trovafloxacin (a fluoroquinolone antibiotic whose use was restricted because of idiosyncratic hepatotoxicity) produced transcriptome changes that were distinct from those produced by other fluoroquinolones that rarely, if ever, produce hepatotoxicity (133). It remains to be determined whether the application of genomics technology to animal models or to cultured human hepatocytes will reduce the risk of idiosyncratic hepatotoxicity for new drugs currently in the P.1017 development pipeline. However, these techniques may speed preclinical testing by providing earlier signals of toxicity and may lead to the discovery of the new biomarkers of liver injury that can be used in the clinic.

Summary and Future Directions The understanding of mechanisms underlying predictable liver toxicity, particularly acetaminophen-induced liver injury, has improved substantially in recent years. There has been identification of many new proteins involved in determining the extent of initial liver injury and those involved in the balance between recovery and progression. It seems logical that variation in these proteins will in part underlie susceptibility to idiosyncratic hepatotoxicity. However, testing this hypothesis will probably require studying people who have actually experienced idiosyncratic hepatotoxicity. The Drug-Induced Liver Injury Network (134) has been recently established to create a registry of such individuals and to collect serum and genomic DNA. Some susceptibility factors are likely to be highly drug specific, and meaningful study may therefore require collection of many patients with liver injury due to the same drug. However, it also seems likely that key components of susceptibility lie in the “downstream” events that may not be molecule specific and can therefore be identified by pooling subjects with toxicity to different drugs. Time will tell.

Annotated References Bugelski PJ. Genetic aspects of immune-mediated adverse drug effects. Nat Rev Drug Discov 2005;4(5):410–420. This is a good review of how drugs can stimulate the body's immune system, resulting in an adverse event. Although not specific to hepatotoxicity, most points are relevant, including a brief discussion of the “Danger hypothesis.” Dambach DM, Andrews BA, Moulin F. New technologies and screening strategies for hepatotoxicity: use of in vitro models. Toxicol Pathol

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2005;33(1):17–26. This is a concise but broad overview of preclinical techniques currently used to screen compounds for hepatotoxic potential. The promise and limitations of genomic techniques are also discussed. Evans DC, Watt AP, Nicoll-Griffith DA, et al. Drug-protein adducts: an industry perspective on minimizing the potential for drug bioactivation in drug discovery and development. Chem Res Toxicol 2004;17(1):3– 16. This review summarizes an approach used by a major pharmaceutical company to screen compounds for reactive metabolite formation, including background on the rationale for this approach. Data obtained from the study of numerous drugs are presented. Liebler DC, Guengerich FP. Elucidating mechanisms of drug-induced toxicity. Nat Rev Drug Discov 2005;4(5):410–420. This review focuses on various ways in which drugs can cause a toxic outcome, including a concise overview of the role of signaling pathways and networks. The impact of mRNA transcript and metabonomics profiling is also presented. Park BK, Kitteringham NR, Maggs JL, et al. The role of metabolic activation in drug-induced hepatotoxicity. Annu Rev Pharmacol Toxicol 2005;45:177–202. This is a concise and current overview of the role of reactive metabolites in drug-induced liver injury, with excellent brief discussions on mechanisms underlying hepatotoxicity due to acetaminophen, halothane, isoniazid, diclofenac, and thiazolidine diones.

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Editors: Title:



Copyright ©2007 Lippincott Williams & Wilkins > Table of Contents > Volume 2 > Section VII - Genetics and Metabolic Disease > Chapter 35 - Wilson Disease

Chapter 35 Wilson Disease Michael L. Schilsky Anthony S. Tavill

Key Concepts z

Wilson disease is a genetic disorder in which copper accumulates in the liver and brain in excess of normal metabolic needs. The accumulation is based on an inherited defect in the hepatic biliary excretion of copper.

z

The inheritance pattern is autosomal recessive. Homozygotes for this disorder, numbering about 1 in 30,000 of the population, inherit diseasespecific mutations of both alleles of the gene for Wilson disease, ATP7B, on chromosome 13. The disease does not develop in heterozygotes with a mutation of a single ATP7B allele, and they do not require treatment.

z

The diagnosis of Wilson disease is established by a combination of clinical and biochemical findings, most notably a decrease in levels of circulating ceruloplasmin, the presence of corneal Kayser-Fleischer (K-F) rings, and a hepatic copper concentration above 250 mg/g dry weight of liver.

z

Molecular genetic studies demonstrating two disease-specific mutations of ATP7B may be used to establish a diagnosis of Wilson disease, but clinical and biochemical evaluation are needed to demonstrate phenotypic expression and to stage the disease.

z

In most symptomatic patients, treatment with metal chelating agents is effective in stabilizing or reversing the disease. Asymptomatic patients may be treated with metal chelating agents or zinc salts. In all circumstances, lifelong pharmacologic treatment is required and results in excellent patient survival.

z

Fulminant hepatic failure in Wilson disease or hepatic insufficiency unresponsive to medical therapy is best treated with orthotopic liver transplantation (OLT), which, by providing the liver with a normal physiologic capacity for copper excretion, is curative.

History In 1912, while serving as a senior resident at the National Hospital for Nervous Diseases in London, Kinnier Wilson published his work Progressive Lenticular Degeneration: a Familial Nervous Disease Associated with Cirrhosis of the Liver as part of his dissertation for the MD degree (1). Correctly, he speculated that the brain disease, characterized by extrapyramidal features, was caused by the liver disease. However, his concept of a “morbid toxin” produced by the cirrhotic

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liver, although strictly correct, could not have anticipated the much later insights into the role of the liver in copper metabolism and the vulnerability of certain areas of the brain to the toxic effects of excessive copper deposition. It was not until 33 years later that Glazebrook (2) detected a marked excess of copper in the basal ganglia of a patient dying of Wilson disease and surmised from the recognized accumulation of copper in the liver that P.1024 the inability of the liver to excrete copper was the dysfunction responsible for the lenticular degeneration, a pathogenetic association later confirmed by other workers (3,4). In 1902 and 1903 the first descriptions of corneal pigmented rings, now recognized eponymously as Kayser-Fleischer (K-F) rings, were based on observations in patients with neurologic disease (5,6). Fleischer (7) was the first to associate three seminal features of Wilson disease—namely, corneal pigmentation, neuropsychiatric disease, and hepatic cirrhosis—and another 10 years passed before the first hypothesis that the corneal pigmentation is caused by the pathologic deposition of copper was proposed (8,9). Recognition of the value of a low serum ceruloplasmin concentration in the diagnosis of Wilson disease came from the observations of Scheinberg and Gitlin (10), who first reported this phenomenon in 96% of Wilson disease homozygotes. However, Sternlieb and Scheinberg (11) subsequently recognized that up to 20% of heterozygotes also have low ceruloplasmin concentrations without any other clinical manifestations of Wilson disease. This observation and the presence of a normal ceruloplasmin in a small minority of Wilson disease homozygotes argued against a direct pathogenetic role for ceruloplasmin in the accumulation of copper in tissues in case of Wilson disease. With the understanding that the clinical features of Wilson disease are the result of copper toxicity in the various affected tissues of the body, the rationale for chelation therapy became apparent. The first chelation agent used for the treatment of Wilson disease, in 1951, was British anti-Lewisite (BAL), or dimercaptopropanol (12,13). This drug, which is lipophilic and therefore administered intramuscularly, enhances cupriuresis and provided the first effective therapy for a previously untreatable disorder. John Walshe of Cambridge University, while working at the Boston City Hospital, introduced the first effective oral chelation therapy in the form of penicillamine and demonstrated its cupriuretic action and role in the symptomatic improvement of patients with lifethreatening features of Wilson disease (14). Sternlieb and Scheinberg (11) subsequently expanded the use of this drug to include the treatment of asymptomatic (or presymptomatic) patients with Wilson disease by showing its effectiveness in preventing disease progression. Walshe (15) proceeded to develop another, safer chelating agent, triethylene tetramine (trientine), which proved a valuable alternative agent in the treatment of those patients intolerant of the toxic effects of penicillamine. Walshe (16) was also instrumental in the initial human use of tetrathiomolybdate, currently an investigational drug in the United States.

Table 35.1. Milestones in the Genetics of Wilson Disease

Year

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Milestone

References

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1912

Recognition of Wilson disease as an

(1,21)

inherited disorder

1953

Pattern of inheritance described as

(22)

autosomal recessive

1985

Localization of disease locus to

(23)

chromosome 13 by linkage with esterase D

1986–

Localization of the responsible gene to a

1993

specific region in chromosome 13

1992–

Identification of the gene for Menkes

1993

disease as a putative copper-transporting

(24,25)

(26,27,28)

P-type ATPase

1993

Identification of the gene for Wilson

(29,30,31,32)

disease, ATP7B, and disease-specific mutations

1994– present

Continued studies on disease-specific mutations and polymorphisms of ATP7B

(33,34)

ATPase, adenosine triphosphatase.

The possibility of preventing the toxic accumulation of copper in Wilson disease by blocking the absorption of copper with oral zinc therapy was first considered by Schouwink (17). Although oral zinc therapy would not be regarded as appropriate for the management of newly diagnosed, symptomatic Wilson disease, subsequent studies have shown it to be an effective alternative to chelation agents for long-term maintenance therapy (18,19). A development that revolutionized the treatment of a subset of patients with Wilson disease presenting with acute liver failure was orthotopic liver transplantation (OLT), which effectively cures the disease (20). The phenotypic reversion from a diseased to a normal state in transplant recipients demonstrates the central role of the liver in Wilson disease and copper metabolism. The recognition of Wilson disease as an inherited disorder, defined by a complex of signs and symptoms, has evolved in less than a century to the point at which we are now able to define the molecular basis for the pathophysiology of this disorder. Milestones in this process, which culminated in the identification of the gene for Wilson disease, designated ATP7B, and the recognition of diseasespecific mutations, are reviewed in subsequent text and outlined in Table 35.1.

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Genetics Although Wilson correctly recorded the familial nature of the disease, it was Hall (21) in 1920 who demonstrated its inheritance, later shown to be autosomal recessive (22). Subsequently, the linkage of Wilson disease to the locus of the red cell esterase-D gene P.1025 placed the gene for Wilson disease on the long arm of chromosome 13 (23), and additional studies further delineated its chromosomal localization (24,25). A breakthrough in the understanding of the molecular basis of the defect of copper metabolism in Wilson disease was the discovery of the gene for Menkes disease, another rare inherited disease of copper metabolism, and the identification of its gene product, ATP7A, a cation-transporting P-type adenosine triphosphatase (ATPase) involved in copper transport in many tissues (26,27,28). The extrapolation of the copper-transporting P-type ATPase to the Wilson disease model led to the hypothesis that a mutation in the gene for a liver-specific copper transporter might be responsible for the association between the defective incorporation of copper into ceruloplasmin, failure of biliary secretion of copper, and accumulation of copper in the liver. The isolation and identification of the gene for Wilson disease, designated ATP7B, followed closely the discovery of the gene for Menkes disease. The identification of the specific gene was accomplished almost simultaneously by three independent laboratories (29,30,31,32). The detection of specific mutations unique to individuals with clinical and biochemically proven disease confirmed the identity of the responsible gene (29,30). The ATP7B gene is contained within an approximately 80-kb region of DNA containing 22 exons (exon 22 being contained in a rare transcript); these encode an approximately 7.8-kb messenger ribonucleic acid that is highly expressed in the liver (33). Analysis of the gene sequence indicates that ATP7B belongs to a family of ATP-dependent metal transporters that are highly conserved through evolution (34). A schema of the ATP7B gene showing specific regions of known homology to ATPases and metal transporters is shown in Figure 35.1. Screening for mutations of ATP7B has led to the identification of a large number (>200) of disease-specific mutations and polymorphisms of the gene (30,31,34,35,36). Most of the mutations thus far identified are point mutations that result in amino acid substitutions. However, deletions, insertions, missense, and splice site mutations have also been reported. A summary of the mutations and polymorphisms of the gene can be found in the following Web site: http://www.medicalgenetics.med.ualberta.ca/wilson/index.php. However, when particular mutations are found frequently among members of a specific population or ethnic group, direct mutational analysis is particularly useful. Haplotype analysis (polymorphism analysis of the region surrounding ATP7B) has proved useful for genetic screening of siblings of probands (see subsequent text). The most frequently observed point mutation, which results in a change from histidine to glutamine (H1069Q), is present in nearly 30% of patients of European descent (30,36). In only a single population in Austria has the frequency of this mutation been reported to be higher (up to 65%) (37). Most mutations are clustered about several transmembrane regions of the protein and in another region predicted to be involved in ATP binding. Some evidence indicates that mutations that result in loss of the expression of the ATP7B protein may cause more severe phenotypic expression; however, not all studies support

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this conclusion. Another study suggests that expression of another gene, APOE, may modify the phenotype of Wilson disease. Polymorphisms in other genes involved in copper metabolism may also modify the disease phenotype, as suggested by studies of MURR1 (38), the gene responsible for copper toxicosis in Bedlington terriers but whose function is not yet certain. Further investigations are ongoing that aim to correlate specific phenotypic presentations or manifestations of Wilson disease with ATP7B genotype and the expression of other potential modifying genes.

▪ Figure 35.1 Predicted major structural features of the Wilson disease gene product (ATP7B). ATP7B, as a member of a class of heavy metal– transporting adenosine triphosphatases (ATPases), is predicted to contain the following structural features: Cysteine-rich metal-binding regions near the amino terminus, a transduction and phosphatase domain, multiple transmembrane regions with one containing the amino acids cysteineproline-cysteine (CPC), a phosphorylation domain (DKTGT), an ATP-binding region (NDGT), a hinge region (GDGVND), and a conserved domain for metal-transforming ATPase, critical for copper transfer (SEHPL). (Adapted from Petrukhin K, Fischer SG, Pirastu M, et al. Mapping, cloning and genetic characterization of the region containing the Wilson disease gene. Nat Genet 1993;5:338–343, and Cox DW. Molecular advances in Wilson disease. In: Boyer JL, Ockner RK, eds. Progress in liver disease. Philadelphia, PA: WB Saunders, 1996:245–264, with permission.)

Pathophysiology Copper is an essential cofactor for many enzymes and proteins and is important for the mobilization of tissue iron stores. The normal pathways for copper metabolism are outlined in Figure 35.2. Ingested copper P.1026 is extracted from the portal circulation by hepatocytes, possibly by the newly discovered cell surface human copper transporter (hCTR1) (39). Intracellular copper then interacts with low-molecular-weight ligands such as glutathione (40), metallothionein (41), and HAH1 (42), which serve as transfer or storage agents, and is subsequently used for cellular metabolic needs, incorporated into the secretory glycoprotein ceruloplasmin, or excreted into bile.

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▪ Figure 35.2 Copper metabolism and pathophysiology of Wilson disease. Dietary copper is absorbed in the proximal small intestine, whereas nonabsorbed copper or copper bound within shed enterocytes passes into the feces. Absorbed copper is bound mainly to albumin in the portal circulation, from which it is avidly extracted by hepatocytes. Hepatocellular copper is bound to ligands and used for metabolic needs, transferred to endogenous chelators, incorporated into ceruloplasmin, or excreted into bile. Biliary copper does not undergo enterohepatic recycling and is therefore excreted in the feces. In Wilson disease, biliary copper excretion is reduced, and copper accumulates within hepatocytes. The incorporation of copper into ceruloplasmin is also impaired in Wilson disease; as a result, circulating levels of this protein are decreased in most patients. When cellular stores are overloaded or after a hepatocellular injury, the amount of copper released into the circulation is increased. Extraction of the excess of non– ceruloplasmin-bound copper by the kidneys leads to an increase in urinary copper excretion and extrahepatic deposition of this metal. The dietary intake of copper is approximately 2 mg/24 hours, with intestinal absorption varying between 25% and 60% of intake. Fecal excretion is between 1 and 2 mg/24 hours, and urinary copper excretion and renal excretion do not usually exceed 50 mg/24 hours. In Wilson disease, non–ceruloplasmin-bound copper is the precursor of the excessive copper deposited in the tissues.

The passage of copper from hepatocytes to bile is critical for homeostasis of this metal because copper excreted into bile undergoes minimal enterohepatic recirculation (43). The transport of hepatocellular copper to bile is thought to involve a vesicular pathway that is dependent on the function of ATP7B. This protein appears to be present mainly in the trans-Golgi network of liver cells under basal conditions (44) (Fig. 35.3). Interestingly, in recent studies of the homologous Menkes disease protein, ATP7A, this protein was observed to alter its intracellular localization in response to increases in the level of copper (45). Although studies of ATP7B protein suggest that it also redistributes to a vesicular compartment in response to copper loading (44), how the redistribution affects the function of the protein remains to be determined. It is presumed that the vesicular pathway is critical for biliary copper excretion. However, other investigators suggest that ATP7B protein resides in a pericanalicular region and

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relocates directly to the canalicular membrane in response to increased cellular copper (46). If the ATP7B protein is present at this site, it would be involved in the direct transfer of copper to bile. Whether the ATP7B protein resides in the canalicular membrane or whether copper is delivered through this site by vesicular transport, the absence or diminished function of ATP7B results in a decrease in biliary copper excretion, which is responsible for the hepatic accumulation of this metal in Wilson disease (4,47,48,49). Ceruloplasmin is a serum glycoprotein that contains six copper atoms per molecule. It is synthesized predominantly in the liver. Copper is thought to be incorporated into apoprotein ceruloplasmin in the Golgi apparatus (50) and the copper-containing holoprotein secreted from the hepatocyte. Newly transported copper, which is used for ceruloplasmin biosynthesis, must also cross organelle membranes to enter into the protein biosynthetic pathway, a process that is dependent on ATP7B and is absent or diminished in most patients with Wilson disease. A reduction of the incorporation of copper into ceruloplasmin is believed to lead to a reduced circulating level of this protein in most patients with Wilson disease because the non–copper-containing apoprotein is less stable. When copper accumulates beyond the cellular capacity for its safe storage, hepatocellular injury may result. Toxic effects of excess copper include the P.1027 generation of free radicals, lipid peroxidation of membranes and DNA, inhibition of protein synthesis, and alterations in the levels of cellular antioxidants (51). Recent data suggest that both hepatocellular necrosis and apoptosis may be triggered by copper-induced cell damage (52,53). When copper-induced injury occurs, the functional status of the liver is determined by the delicate balance between injury, cell death, and the regenerative capacity of liver cells.

▪ Figure 35.3 Cellular pathways of copper metabolism. Newly absorbed

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copper, loosely bound to albumin, is transported across the plasma membrane of the hepatocyte, where it is transported by a variety of ligands to the Golgi apparatus. There, the ATP7B protein serves to transport it across the Golgi into ceruloplasmin for secretion into the circulation. Excretion into bile may occur by vesicular secretion, by transcanalicular association with glutathione (GSH) through the canalicular organic anion transporter (cMOAT), or by copper-transporting adenosine triphosphatase in the canalicular membrane. hCTR, human copper transporter; MT, metallothionein;

When the capacity of the liver to store copper is exceeded, or when hepatocellular damage results in the release of cellular copper into the circulation, levels of non–ceruloplasmin-bound copper in the circulation become elevated. It is from this pool that the extrahepatic deposition of copper is thought to occur. The brain is the most critical extrahepatic site of copper accumulation, and copper-induced neuronal injury is responsible for the neurologic and psychiatric manifestations of Wilson disease and the characteristic changes on radiologic imaging studies of the brain.

Pathology The evolution of pathologic changes in the tissues of patients with Wilson disease (see ref. 51 for review) follows the relative rates of accumulation of copper in the various body organs. Because the primary genetic defect resides in the liver and because the liver is the predominant storage organ for copper, it is not surprising that the earliest pathologic manifestations are hepatic in nature. As copper “spills” over to other organs from the liver, pathologic manifestations become evident in the brain, kidneys, eyes, and joints.

Hepatic Pathology Macroscopically, the liver may be only mildly enlarged in the early stages of life. Later, without treatment, the liver pathology progresses in most patients to fibrosis and cirrhosis. The nodular transformation of cirrhosis is a mixed macronodular–micronodular pattern, in which the nodules may vary in color depending on the degree of copper accumulation (Fig. 35.4A). The rate of pathologic change varies greatly between patients, and in some cases steatosis and fibrosis without cirrhosis may persist for decades (54). At a microscopic level, the evidence of copper accumulation in early infancy may be subtle and nonspecific. Diffuse cytoplasmic copper accumulation may not be visible by immunohistochemical methods for detecting copper (e.g., rhodanine, rubeanic acid). This early stage of copper accumulation is associated with macrosteatosis, microsteatosis, and glycogenated nuclei, features that may be seen in a variety of other conditions (55) (Fig. 35.4B). Sternlieb (56) emphasized the almost ubiquitous presence of distinctive mitochondrial changes at this early stage of the disease. The P.1028 P.1029 ultrastructural abnormalities range from enlargement and separation of the inner and outer membranes, with widening of the intercristal spaces, to increases in the density and granularity of the matrix or replacement by large vacuoles.

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Pleomorphic changes may also be seen in distorted peroxisomes and endoplasmic reticulum, with nuclei showing glycogen inclusions. With progression of the disease, copper–protein is sequestered in lysosomes, appearing as electron-dense pericanalicular structures visible on light microscopy as granules detectable by copper immunohistochemistry (Fig. 35.5).

▪ Figure 35.4 Light microscopic findings in liver in Wilson disease. A: Masson trichrome stain of liver from a patient with established cirrhosis reveals broad bands of fibrosis intersecting variably sized nodules with varied staining characteristics (×80). B: Prominent microvesicular and macrovesicular steatosis and some inflammatory cells in a specimen from an asymptomatic patient with Wilson disease (×250). C: Hepatocellular ballooning and degeneration in a biopsy specimen from a patient with fulminant Wilsonian hepatitis (×250).

If the condition is untreated or unrecognized, the initial stages of Wilson disease progress to an intermediate hepatic stage; this is characterized by periportal inflammation with mononuclear cellular infiltrates, erosion of the limiting lobular plates, lobular necrosis, and bridging fibrosis, features indistinguishable from those of chronic active hepatitis of many other causes (55). Cirrhosis is virtually invariable at this stage of disease, with either a micronodular or a mixed macronodular-micronodular histologic pattern. Mallory bodies may be visible in

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up to 50% of biopsy specimens. In patients presenting with fulminant hepatic failure, parenchymal necrosis with ballooning of hepatocytes, apoptotic bodies and cholestasis, and collapse may predominate (Fig. 35.4C). In some of these individuals with fulminant failure, the liver has significant collapse and bridging fibrosis but cirrhosis may not be present (M. Schilsky, J. Lefkowitch, personal observations, 2005). A histochemical confirmation of copper deposition may be helpful; however, a negative result does not exclude copper overload. Rhodanine and rubeanic acid may show dense granular lysosomal copper deposition in hepatocytes at the stage of cirrhotic nodular regeneration. Staining at this stage often shows marked variability from nodule to nodule (Fig. 35.6). Paradoxically, the results of immunohistochemical staining for copper are usually negative in the earlier stages of the disease, when the hepatocyte copper is diffusely distributed in the cytoplasm (57). A more sensitive stain, Timms sulfide, is more effective in detecting cytoplasmic copper-binding proteins; however, it is not routinely utilized.

Neuropathology Macroscopically, most of the overt neuropathologic changes in advanced Wilson disease are concentrated in the lenticular nuclei. These show atrophy and discoloration, with cystic degeneration, pitting, and fissuring of the cut surfaces. Similar changes have been described in the thalamus, subthalamic region, and even the cerebral white matter (58). Microscopically, the major pathologic changes occur in those parts of the central nervous system with the highest copper levels. Scheinberg and Sternlieb (58) calculated that the concentrations are highest in the thalamus, followed by the putamen and cerebral cortex. Neuroglial changes are the most distinctive in Wilson disease, with an increase in the number of astrocytes in the gray matter of the lenticular nuclei. Swollen glia may undergo cavitation and liquefaction, which create small cavities with an overall appearance of spongiform degeneration. Neuronal loss is accompanied by gliosis and astrocytosis and the production of glial fibrillary protein. The characteristic astrocytes seen within areas of lenticular degeneration are Alzheimer type I and II cells and, distinctively for Wilson disease, Opalski cells (59), which are large cells, up to 35 µm in diameter, with fine granular cytoplasm and slightly eccentric nuclei (single or multiple) that Scheinberg and Sternlieb (58) suggested originate from degenerating astrocytes. It is unclear at the present time whether the glial changes are secondary to the stimulation of metallothionein protein synthesis by copper in selective areas of the brain populated by protoplasmic astrocytes or whether the selective targeting of glial cells is related to other, as yet unidentified, factors.

Miscellaneous Pathologic Changes Functional changes in the kidneys are often disproportionate to any observable changes on light microscopy. Proximal or distal tubular dysfunction leading to tubular proteinuria, bicarbonate loss, aminoaciduria, glycosuria, hyperphosphaturia, uricosuria, and hypercalciuria is common. Glomerular abnormalities, in the form of hypercellularity, basement membrane thickening, hyalinization, and fibrosis, have been described (58). Penicillamine-induced immune complex nephropathy has been described. Bone pathology and

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periarticular abnormalities have been observed, accounting for osteoporosis, osteomalacia, spontaneous fractures, adult rickets, osteoarthritis, osteochondritis dissecans, chondrocalcinosis, and subchondral cyst formation (58). Involvement of the spine and knee joints is the most common distribution of skeletal and articular abnormalities. Ophthalmologic findings include K-F rings and sunflower cataracts. The K-F rings, most marked at the upper and lower poles of the cornea, are caused by the granular deposition of elemental copper on the inner surface of the cornea in the Descemet membrane (Fig. 35.7). The rings have a golden brown or green appearance on slit-lamp examination. The sunflower cataracts, with radiating centrifugal extensions, are associated with the granular deposition of copper in the anterior and posterior lens capsule. Both the K-F rings and sunflower cataracts are reversible with effective P.1030 P.1031 therapy for Wilson disease. Classic K-F rings are caused exclusively by the presence of excess copper in the Descemet membrane; however, rings indistinguishable from K-F rings have been seen in other forms of chronic liver disease, particularly those characterized by prolonged cholestasis (60). On slitlamp examination, they resemble K-F rings, but chemical analysis has not confirmed that they are caused by copper deposition, although it has been hypothesized that such patients may show excessive copper retention.

▪ Figure 35.5 Electron micrographs of fine sections of liver biopsy specimens obtained from untreated patients with Wilson disease, showing portions of hepatocytes. A: Ten-year-old asymptomatic girl with normal

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physical findings: Aspartate aminotransferase, 76 IU/L; alanine aminotransferase, 55 IU/L; serum ceruloplasmin, 21.4 mg/dL; hepatic copper, 1,258 mg/g of dry tissue. Some of the mitochondria display vacuoles (V) with granular material. Note separation of inner from outer membrane (arrowheads), with creation of an enlarged intermembranous space. L, lipid droplet. B: Nineteen-year-old woman with a history of progressive fatigue, found to have Kayser-Fleischer rings 2 months after an episode of hemolytic anemia with jaundice: Serum ceruloplasmin, 12.7 mg/dL; hepatic copper, 591 mg/g of dry tissue. The mitochondria are markedly pleomorphic, some displaying multiple, pathognomonic abnormalities: Gigantism, increased matrical density, separation of inner from outer membrane (arrowhead), vacuoles, dilated cristae, crystals, and enlarged dense granules (G). P, peroxisomes. C: Ten-year-old asymptomatic girl with serum ceruloplasmin level below 1 mg/dL and a hepatic copper concentration of 1,029 mg/g of dry tissue. Mitochondria (M) display dilated cristae; the markedly enlarged peroxisomes (P) with grainy matrices are strikingly abnormal. D: In a 20year-old woman with severe neurologic Wilson disease, the hepatocellular cytoplasm appears virtually normal except for the abundance of electrondense, peribiliary, lysosomal granules (Ly). BC, bile canaliculus; M, mitochondria.

▪ Figure 35.6 A,B: Liver section stained with rhodanine to show nodule with heavy lysosomal copper deposition in adjoining liver tissue with minimal copper staining; (A) low power ×110 and (B) high power ×200.

Diagnosis The diagnosis of Wilson disease should be considered in any person aged between 3 and 40 years with unexplained hepatic, neurologic, or psychiatric disease, although rare cases have been diagnosed in persons in the sixth, seventh, and even eighth decades of life (54). In particular, this diagnosis must be excluded unequivocally in children or young adults who present with unusual extrapyramidal or cerebellar motor disorders, atypical psychiatric disease,

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unexplained hemolysis, or elevated liver enzyme levels or other manifestations of liver disease, with or without a family history of liver or neurologic disease. The failure to do so will lead to unnecessary and preventable demise. In most cases, the diagnosis can be made by a combination of clinical and biochemical testing. In practice, three levels of tests may be undertaken to confirm the diagnosis of Wilson disease (Table 35.2). The presence of K-F rings and a reduced serum concentration of ceruloplasmin are sufficient to establish the diagnosis. However, in the absence of K-F rings, it is necessary to proceed to a liver biopsy for a quantitative copper determination to confirm the diagnosis.

▪ Figure 35.7 Kayser-Fleischer ring in a 17-year-old patient with neurologic symptoms of Wilson disease.

Molecular testing is currently available for Wilson disease. There are two types of testing that may be employed. Haplotype analysis that looks for familial inheritance of polymorphisms around the ATP7B gene should be considered for use in screening the siblings of affected persons. Direct mutational analysis is now available for de novo diagnosis of Wilson disease. Newer methodology has made the molecular screening of the entire coding region of ATP7B less cumbersome and time consuming, although some targeting of specific exons with higher frequencies of mutations may make sense while testing in individual populations in which specific mutations are present at higher frequency. There is a need to identify disease-specific mutations of the gene to firmly establish the diagnosis without biochemical testing. Although molecular studies may detect the disease, it may still be useful to fully characterize patients with the disorder who are detected by standard testing to better understand the degree of disease involvement, as well as to provide confirmation of the diagnosis. Given the current relative high cost and complexity of this testing, molecular testing will not readily be used as a screening test for Wilson disease. However, for patients in whom there is P.1032 difficulty in determining the diagnosis by clinical and biochemical testing, molecular testing should prove extremely useful.

Table 35.2. Diagnostic Tests in Wilson Disease

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Level 1

Level 2

Level 3

Low serum

Liver copper

Incorporation of

ceruloplasmin (a)

concentration (c)

radiocopper into ceruloplasmin

Slit-lamp

—

Ultrastructural studies of

examination for K-F

hepatocytes

rings

Raised serum-free

24-h urine copper

Molecular genetic studies

copper level (b)

(d)

for Wilson disease

Normal values: (a) 20–50 mg/dL; (b) Table of Contents > Volume 2 > Section VII - Genetics and Metabolic Disease > Chapter 36 Hemochromatosis a nd Iron Storage Disorders

Chapter 36 Hemochromatosis and Iron Storage Disorders Bruce R. Bacon Robert S. Britton

Key Concepts z

An increase in systemic iron levels is the consequence of (a) inherited excessive intestinal absorption of dietary iron (hereditary hemochromatosis), (b) ineffective erythropoiesis or chronic liver disease, or (c) parenteral iron administration. Excessive intracellular deposition of iron ultimately results in tissue and organ damage.

z

Hereditary hemochromatosis (HH) constitutes several inherited disorders characterized by an increased intestinal absorption of iron with its subsequent accumulation in tissues. Most (approximately 90%) patients with HH have mutations in HFE, and HFE-related HH is one of the most common inherited disorders among whites, with a frequency of about 1 in 250.

z

Two independent mutations of the HFE gene are principally responsible for HFErelated HH. These mutations result in a change of cysteine to tyrosine at amino acid 282 (C282Y) and of histidine to aspartic acid at amino acid 63 (H63D) of the HFE protein. Approximately 95% of persons with HFE-related HH are homozygous for the C282Y mutation. Population studies indicate that the penetrance of the C282Y mutation is incomplete, and genetic modifiers may be involved. Some compound heterozygotes with copies of both the C282Y and H63D mutations have a clinically significant degree of iron overload.

z

Mutations in the iron-related genes encoding for hemojuvelin, hepcidin, ferroportin, transferrin receptor 2 (TFR2), divalent metal transporter 1 (DMT1), and ferritin result in non–HFE-related HH.

z

The pathogenesis of nearly all forms of HH involves inappropriately low expression of the iron-regulatory hormone hepcidin, which acts to decrease the export of iron from absorptive enterocytes and reticuloendothelial (RE) cells. Hepcidin is highly expressed in hepatocytes, and it is proposed that HFE protein, TFR2, and hemojuvelin all play a role in the hepatic iron-sensing pathway that regulates hepcidin expression. The C282Y mutation causes functional inactivation of the HFE protein, leading to low hepcidin expression with a resultant increase in duodenal iron absorption.

z

In HFE-related HH, the excess iron is preferentially deposited in the cytoplasm of parenchymal cells of various organs and tissues, including the liver, pancreas, heart, endocrine glands, skin, and joints. Damage can result in micronodular cirrhosis of the liver and atrophy of the pancreas (primarily islets). Hepatocellular carcinoma, usually in the presence of cirrhosis, is another consequence of excess iron deposition in the liver. Symptoms are related to damage of the P.1042 involved organs and include liver failure (from cirrhosis), diabetes mellitus, arthritis, cardiac dysfunction (arrhythmias and failure), and hypogonadotropic hypogonadism.

z

The diagnosis of iron overload includes serum iron studies (elevated transferrin saturation [TS], elevated serum ferritin levels), genetic testing, and sometimes liver biopsy to assess the hepatic iron concentration and degree of liver injury. In cases of

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HFE-related HH, liver biopsy is usually not indicated if the patient has normal liver enzyme levels and a serum ferritin level below 1,000 ng/mL. Because regular phlebotomy therapy prevents or reverses the accumulation of excess iron and prevents the complications of HH, it is important to identify persons with this inherited disorder early in the disease process.

History The first medical description of a patient with hemochromatosis was by Trousseau (1) in the French pathology literature in 1865 (Table 36.1). Twenty-four years later, the German pathologist von Recklinghausen (2) was the first to use the term hemochromatosis; he thought that the pigmentation (“chrom”) in the tissues of patients with the disorder was caused by something circulating in their blood (“hemo”). In 1935, Joseph Sheldon (3), a British geriatrician, published a monograph describing the 311 cases of hemochromatosis that existed in the world literature up to that time. Sheldon concluded that hemochromatosis is an inherited disorder in which tissue injury and damage results from excess iron deposition. He drew accurate conclusions without the techniques of modern molecular medicine available today. The situation was somewhat confused by MacDonald (13), a pathologist at the Boston City Hospital, who believed that hemochromatosis was a nutritional disorder, possibly because he saw many alcoholic patients who happened to be of Irish descent. It is now known that the prevalence of homozygosity for HFE-related hereditary hemochromatosis (HH) is high in the Irish population, approaching 1 in 70 persons (14). In 1976, Marcel Simon et al. (7) definitively showed that classic hemochromatosis is inherited as an autosomal recessive disorder, with linkage to the human leukocyte antigen (HLA) region of the human genome; the gene for hemochromatosis is located on the short arm of chromosome 6. It took another 20 years until the research group at Mercator Genetics successfully identified and cloned the hemochromatosis gene by means of a positional cloning approach using deoxyribonucleic acid (DNA) samples from well-documented patients with hemochromatosis in the United States (9). In 1996, Feder et al. (9) identified HFE, a novel major histocompatibility complex (MHC) class I–like gene; homozygosity for a single missense mutation (C282Y) of HFE was found in 83% of the patients who were studied. Quickly, several other groups reported their findings in series of patients with hemochromatosis, and homozygosity for the C282Y mutation was found in about 85% to 90% of typical patients (15,16,17,18,19). This discovery has yielded significant benefits in clinical medicine and hepatology, including P.1043 more accurate diagnosis of HFE-related HH, improved family screening, and evaluation of the role of HFE mutations in other liver diseases. Additionally, there has been a wealth of new information about the cellular and molecular mechanisms of iron homeostasis, including the discovery of the iron-regulatory hormone hepcidin. In this chapter, we highlight the new advances in the area of HH and other iron storage disorders, interdigitating these discoveries with the classic pathologic and clinical features seen in these patients.

Table 36.1. Milestones in HFE-Related Hereditary Hemochromatosis

Year

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Authors (refs.)

Event

~1–300 AD

—

C282Y mutation of HFE in Celtic population

1865

Trousseau (1)

First case described

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1889

von Recklinghausen (2)

Coined the term hemochromatosis

1935

Sheldon (3)

Postulated HH is an inherited defect of iron metabolism

1950

Davis et al. (4,5)

First liver biopsy in HH, and first phlebotomy therapy

1976

Bomford and Williams (6)

Benefit of phlebotomy therapy described

1976

Simon et al. (7)

Linkage to HLA-A

1985

Niederau et al. (8)

Benefit of early diagnosis and therapy

1996

Feder et al. (9)

HFE gene cloned, and C282Y and H63D mutations described

1998

Zhou et al. (10)

HFE knock-out mouse has iron overload

2001

Nicolas et al. (11)

Hepcidin as iron-regulatory hormone

2003

Bridle et al. (12)

Low hepcidin expression in HFE-related HH

1997– present

Many

Cell biology of iron-related proteins

HH, hereditary hemochromatosis; HLA, human leukocyte antigen.

Classification of Iron Overload Syndromes Many terms have been used in the past to describe HH, such as idiopathic, primary, and familial. The term hereditary hemochromatosis should be reserved to describe inherited disorders of iron metabolism that lead to tissue iron loading (Table 36.2). The most common form of this disease, HFE-related HH, is caused primarily by homozygosity for the C282Y mutation in the HFE gene. However, other heritable forms of iron overload have also been recognized (non–HFE-related HH). These include (a) autosomal recessive forms of HH characterized by rapid iron accumulation and caused by mutations in the genes for hemojuvelin and hepcidin (also called juvenile hemochromatosis) (20,21), (b) an autosomal dominant form of HH caused by mutations in the ferroportin gene (22,23), (c) an autosomal recessive form of HH resulting from mutations in the gene for transferrin receptor 2 (TFR2) (24,25), and (d) rare forms of HH resulting from mutations in the divalent metal transporter 1 (DMT1) gene (26) or in the regulatory region of ferritin messenger ribonucleic acid (mRNA) (27). Some other types of iron overload may have a heritable component but the genes involved have not yet been identified. For example, African iron overload is a familial disorder of iron loading prevalent in sub-Saharan Africa

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that is exacerbated by the ingestion of iron-rich home-brewed beer (28,29,30). The degree of iron loading can be similar to that in HFE-related HH, but the cellular and lobular distribution of iron is different. In addition, a rare disorder termed neonatal iron overload is characterized by increased hepatic iron and severe liver injury present at birth (31,32,33).

Table 36.2. Classification of Iron Overload Syndromes

HEREDITARY HEMOCHROMATOSIS HFE-related C282Y/C282Y C282Y/H63D Other HFE mutations Non–HFE-related Hemojuvelin (HJV) mutations (autosomal recessive) Hepcidin (HAMP) mutations (autosomal recessive) Ferroportin (SLC40A1) mutations (autosomal dominant) Transferrin receptor 2 (TFR2) mutations (autosomal recessive) Divalent metal transporter 1 (SLC11A2) mutations (rare) Ferritin regulatory mutations (rare) Miscellaneous African iron overload Neonatal iron overload (rare) SECONDARY IRON OVERLOAD Anemia caused by ineffective erythropoiesis Thalassemia major Sideroblastic anemias Congenital dyserythropoietic anemias Congenital atransferrinemia Aceruloplasminemia Liver disease Alcoholic liver disease Chronic viral hepatitis B and C Porphyria cutanea tarda Nonalcoholic steatohepatitis After portacaval shunt Miscellaneous Excessive iron ingestion PARENTERAL IRON OVERLOAD Red blood cell transfusions Iron–dextran injections Associated with long-term dialysis

Several noninherited syndromes of iron overload are known. In secondary iron overload, an underlying disorder causes an increase in iron absorption; examples are disorders of ineffective erythropoiesis and liver disease (34,35). Parenteral iron overload is an iatrogenic disorder in which blood transfusions or iron–dextran injections are given to patients who are anemic (36). In HFE-related HH, it has become clear from population studies that not all individuals who have the C282Y/C282Y genotype become iron loaded. This observation indicates that there are many nonexpressing C282Y homozygotes in the population (37,38,39) and has led to a four-category description of HFE-related HH: (a) Genetic predisposition with no other abnormality, (b) iron overload (approximately 2 to 5 g) but without symptoms or tissue damage, (c) iron overload with early symptoms (i.e., lethargy, arthralgias), and (d) iron overload with organ damage, particularly cirrhosis.

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HFE-Related Hereditary Hemochromatosis Since the work of Simon et al. in the mid-1970s (7), it has been known that the major gene for HH is located on the short arm of chromosome 6 in the HLA region of the genome. In 1996, investigators at Mercator Genetics used a positional cloning approach to identify HFE P.1044 as the responsible gene (9). HFE codes for a novel MHC class I–like protein that requires interaction with β 2 -microglobulin (β 2 M) for normal presentation on the cell surface (9). Structural homology with other MHC class I proteins and x-ray crystallographic studies indicate that HFE protein has a large extracellular domain with three α loops, a single transmembrane region, and a short cytoplasmic tail (9,40). In the original work by Feder et al. (9), two missense mutations were identified in HFE, one resulting in a change of cysteine to tyrosine at amino acid 282 (C282Y) and the second causing a change of histidine to aspartate at amino acid 63 (H63D). Other HFE mutations have been identified, but their frequency appears to be low and their clinical impact is limited. Feder et al. (9) reported that 148 (83%) of 178 patients with typical phenotypic HH were homozygous for the C282Y mutation while 8 (4%) patients were compound heterozygotes, with one allele containing the C282Y mutation and the other allele containing the H63D mutation. These findings were confirmed by subsequent studies that showed that 60% to 100% (mean value, 84%) of patients with typical phenotypic HH were homozygous for C282Y (15,16,17,18,19). Of interest, approximately 6% of patients in these studies, in aggregate, had a clinical syndrome phenotypically similar to that of patients with typical HH but were negative for either HFE mutation (19). Some of these patients may have had mutations in known iron-related genes or in as yet unidentified genes involved in iron metabolism.

HFE Gene and Protein The HFE gene is expressed at relatively low levels in most human tissues (9), and Northern blot analysis of lineage-specific human cell lines demonstrates an abundant expression of HFE mRNA in cells of epithelial or fibroblastic origin (41). However, unlike other classic MHC class I genes, HFE is rarely expressed in lymphopoietic and hematopoietic cells (9). Little is known of the regulation of HFE gene expression. In contrast to the expression of genes for other MHC molecules, HFE expression is not induced in cultured cells by various cytokines (42). Although in one study of a human intestinal cell line (Caco2) the levels of HFE mRNA and protein increased as iron status increased (43), in another study, neither iron chelation nor iron replacement affected HFE mRNA levels (44). Sequences known to confer transcriptional regulation by cellular metal ion content have not been identified in the HFE gene. Furthermore, sequences homologous to iron-responsive elements (IREs) have not been identified in either the 3′- or 5′-untranslated region of HFE mRNA. However, several splice variants of human HFE mRNA have been identified. An HFE transcript lacking exons 6 and 7 has been detected (by means of reverse transcription followed by polymerase chain reaction) in human duodenum, spleen, breast, skin, and testicle (45). Because this transcript does not include the sequences encoding the transmembrane and cytoplasmic domains, it is predicted to encode a secretory form of HFE protein. HFE splice variant transcripts lacking exon 2 and/or a portion of exon 4 have been identified in a human liver cell line, a colon carcinoma cell line, and an ovarian cell line (46). Deletion of exon 2 is predicted to eliminate the α 1 loop of HFE protein, whereas deletion of a portion of exon 4 is predicted to affect the α 3 loop. The levels of protein expression and physiologic roles of the splice variant HFE transcripts are not yet known. The HFE gene encodes a 343–amino acid protein consisting of a 22–amino acid signal peptide, a large extracellular domain, a single transmembrane domain, and a short cytoplasmic tail (9). HFE protein is widely expressed in several organs including the liver, placenta, and gastrointestinal tract (i.e., epithelium of esophagus, stomach, duodenum, small intestine, and colon) (47,48,49,50,51). The extracellular domain of HFE protein consists of three loops (α 1 , α 2 , and α 3 ), with intramolecular disulfide bonds within the second and third loops. The structure of HFE protein is therefore similar to that of other MHC class I proteins. The two common HFE mutations, C282Y and H63D, are in the

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extracellular domain. Crystallographic studies demonstrate that the α 1 and α 2 loops of HFE protein form a superdomain consisting of antiparallel β strands topped by two antiparallel α helices (40). The groove between the antiparallel α helices is analogous to the peptidebinding groove in antigen-presenting MHC class I proteins. Several lines of evidence, however, suggest that HFE protein does not participate in antigen presentation. The groove between the α helices in HFE protein is physically narrower than that in antigenpresenting MHC class I molecules, so that the ability to bind peptides is precluded. Indeed, N-terminal sequencing performed on acid eluates from HFE protein found no evidence of peptide binding (40). HFE protein, like other MHC class I molecules, is physically associated with β 2 M. This association has been demonstrated in the human duodenum (48) and placenta (47), and in cultured cells (52,53,54).

C282Y mutation of HFE The C282Y mutation results in the substitution of tyrosine for cysteine at amino acid 282 in the α 3 loop and abolishes the disulfide bond in this domain (9). Loss of the disulfide bond was predicted to interfere with the interaction of β 2 M with HFE protein (9). Indeed, C282Y mutant protein expressed in cell culture systems demonstrates diminished binding with β 2 M and P.1045 decreased presentation at the cell surface in comparison with wild-type HFE protein (52,53). The C282Y mutant protein is retained in the endoplasmic reticulum and middle Golgi compartments, fails to undergo late Golgi processing, and is subject to accelerated degradation (53). However, some C282Y mutant protein in patients with HH reaches the cell surface, as detected by immunohistochemistry, although at reduced levels (51). Definitive proof that this mutation can cause HH was provided when knock-in of the C282Y mutation in mice resulted in iron overload (55). The C282Y mutation is present in most, but not all, patients with a clinical diagnosis of HH. The proportion of patients with HH who are homozygous for C282Y varies in different populations. In the United States, Britain, Australia, Canada, and France, approximately 85% to 90% of patients with a clinical diagnosis of HH are homozygous for C282Y (19), but a lower frequency (60%) has been reported in Italy (56). Conversely, population studies have revealed that the clinical features of HH do not develop in many C282Y homozygotes (37,38,39). This observation suggests incomplete penetrance of the C282Y mutation and raises the possibility that other genes involved in iron homeostasis may act as modifiers of the HH phenotype (57,58,59). The prevalence of the C282Y mutation is greatest in whites of European ancestry. In this population, the carrier frequency ranges from 10% to 15% (14,19,32,33,34). In other ethnic populations, the C282Y mutation is less common and is always associated with the ancestral white haplotype (60,61). Such studies suggest that the C282Y mutation occurred once on an ancestral (possibly Celtic) haplotype that spread from northern Europe to other regions of the world (62,63). The observation that the haplotype containing the C282Y mutation extends for approximately 7 megabases suggests that the mutation arose during the last 2,000 years (64). It has been proposed that the C282Y mutation, associated with increased iron absorption and the accumulation of body iron stores, provided a selective advantage to a population in which the availability of dietary iron was limited or in which intestinal parasitic infections caused a loss of iron.

H63D mutation of HFE The most common HFE mutation in the general population is a missense mutation that results in the substitution of histidine for aspartate at amino acid 63 (H63D) of the HFE protein (9). The H63D mutation is found at a frequency of 15% to 40% in white populations (19), but homozygosity for H63D appears to increase the risk for iron loading only slightly (65). However, the frequency of compound heterozygosity for the H63D and C282Y mutations is greater in patients with iron overload than that predicted for the general population (9,19). It is estimated that the risk for iron loading of the C282Y/H63D compound heterozygote is nearly 200-fold lower than that for the C282Y homozygote (66).

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The population distribution of the H63D mutation differs somewhat from that of C282Y. The highest frequencies of H63D are found in European countries bordering the Mediterranean, the Middle East, and the Indian subcontinent (63). The H63D mutation has been found on many haplotypes, which suggests that this less consequential mutation may have arisen historically multiple times and in different populations. Because the haplotype comprising the H63D mutation is shorter (approximately 700 kb) than that of the C282Y mutation, it is thought to be evolutionarily older (64).

Other mutations of HFE HFE mutations other than C282Y and H63D have been identified in isolated patients with iron overload (67,68). These include missense mutations (e.g., S65C, G93R, I105T, and Q127H), splice site mutations (e.g., IVS3+1 G/T and IVS5+1 G/A), frame shift mutations (e.g., V68ΔT, P160ΔC), and nonsense mutations (e.g., R74X, E168X, W169X). Each symptomatic patient carrying one of the missense mutations has carried the C282Y or H63D mutation on the other allele. The two identified splice site mutations cause altered mRNA splicing and exon skipping, resulting in abnormal variants of HFE protein. The frameshift and nonsense mutations result in the production of truncated forms of HFE protein. The relative contribution of HFE mutations other than C282Y or H63D to the overall incidence of HFE-related HH appears to be small.

Experimental disruption of the HFE gene Transgenic methodology has provided important information about the functional consequences of HFE gene disruption in the whole animal. Four different murine models have been generated: An exon 4 knock-out (10), an exon 3 disruption/exon 4 knock-out (55), an exon 2–3 knock-out (69), and a C282Y knock-in (55). These mice manifest increases in hepatic iron levels (10,55,69), transferrin saturation (TS) (10), and intestinal iron absorption (69). No immunologic consequences of HFE disruption have been observed in mice (69). Like patients with HFE-related HH, these mice demonstrate relative sparing of iron loading in reticuloendothelial (RE) cells (10,55). Interestingly, iron loading in mice that are homozygous for the C282Y mutation is less severe than that in HFE knock-out mice, which indicates that the C282Y mutation is not a null allele (55). Strain differences determine the severity of iron accumulation in HFE knock-out mice, supporting the concept that there are genetic modifiers of the HH phenotype (58,70). P.1046

Determinants of Duodenal An increase in intestinal iron absorption is a key characteristic of HH (71,72,73), and, therefore, understanding the pathogenesis of HH requires a review of the determinants of duodenal iron absorption. Because there are no significant physiologic mechanisms to regulate iron loss, iron homeostasis is dependent on tightly linking body iron requirements (approximately 1 mg/day) with intestinal iron absorption. Nearly all absorption of dietary iron occurs in the duodenum, where iron may be taken up either as ionic iron or as heme (73). The absorption of both forms of iron is increased in patients with HH. Uptake of heme occurs by an as yet unidentified transporter. Absorption of ionic iron across the enterocytes occurs in two stages: Uptake across the apical membrane and transfer across the basolateral membrane (Fig. 36.1). Before uptake, ionic iron requires reduction from the ferric to the ferrous state. This is accomplished by the ferric reductases (such as Dcytb), which are expressed on the luminal surface of duodenal enterocytes (74). The ferrous iron crosses the apical membrane using the transporter divalent metal transporter 1 (DMT1) (75,76). Iron taken up by the enterocyte may be stored as ferritin (and excreted in the feces when the senescent enterocyte is sloughed) or transferred across the basolateral membrane to the plasma. This latter process occurs through the transporter ferroportin (77,78,79). The basolateral transfer of iron requires oxidation of iron to the ferric state by the ferroxidase, hephaestin (80). In addition to increased uptake of iron from the diet, patients with HFE-related HH demonstrate increased basolateral transfer of iron from the enterocytes to the plasma, and this may be a driving force behind the increased intestinal iron absorption observed in HFE-related HH (72). Some studies on

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patients with HFE-related HH (81,82,83) and HFE knock-out mice (84,85) have demonstrated increased expression of mRNAs encoding DMT1 and ferroportin. However, not all investigators have observed upregulation of DMT1 and ferroportin in patients with HH (86,87) or in HFE knock-out mice (88,89). In HFE knock-out mice, these discrepancies may be due to differences in mouse strain (70) or age (90).

▪ Figure 36.1 Iron absorption and the role of hepcidin. A: Absorption of dietary ionic iron across the duodenal villus enterocyte occurs in two stages: Uptake across the apical membrane and transfer across the basolateral membrane. Before uptake, ionic iron has to be reduced from the ferric to the ferrous state. This is accomplished by the ferric reductases (such as Dcytb), which are expressed on the luminal surface of duodenal enterocytes. The ferrous iron crosses the apical membrane through the divalent metal transporter 1 (DMT1). Iron taken up by the enterocyte is thought to enter a low-molecular-weight (MW) iron pool and then stored as ferritin or transferred across the basolateral membrane to the plasma. This latter process occurs through the transporter ferroportin. The basolateral transfer of iron requires oxidation of iron to the ferric state by the ferroxidase, hephaestin. Ferric iron is then bound to transferrin in the circulation. B: Hepcidin expression by the liver is upregulated by increased iron, inflammation, or increased oxygen availability. Circulating hepcidin acts to decrease the functional activity of the iron exporter ferroportin by binding to it and causing its internalization and degradation. In reticuloendothelial (RE) cells, this results in iron sequestration while in duodenal enterocytes it leads to decreased basolateral iron transfer and, therefore, decreased dietary iron absorption. Patients with hereditary hemochromatosis have low hepcidin expression with a consequent increase in iron absorption.

Several biologic factors influence the rate of dietary iron absorption. Reduction in body iron stores, increased erythropoietic activity, decreased blood hemoglobin content, and decreased blood oxygen saturation increase the absorption of iron from the diet (73). In contrast, the presence of systemic inflammation decreases dietary iron absorption. All these factors are thought to act by influencing the levels of hepcidin, an iron-regulatory hormone.

Dysregulation of Hepcidin in Hereditary Hemochromatosis Hepcidin is a 25–amino acid peptide, first identified in urine and plasma as an antimicrobial peptide (91,92,93). However, its role in influencing systemic iron status has become paramount, and it is now considered to be the P.1047 principal iron-regulatory hormone (94,95). The first evidence that hepcidin is involved in iron homeostasis came from the observation that liver hepcidin mRNA expression is

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increased in mice with dietary iron loading (93). The fortuitous discovery that knock-out of the hepcidin gene in the mouse led to a HH-like phenotype established the critical role of hepcidin as a negative regulator of intestinal iron absorption (11,96). It was later discovered that hepcidin mutations are responsible for one form of juvenile hemochromatosis (21). Factors regulating intestinal iron absorption (i.e., iron status, erythropoietic activity, hemoglobin levels, oxygen content, and inflammation) also regulate liver hepcidin expression (Fig. 36.2). In each of these situations, intestinal iron absorption varies inversely with liver hepcidin expression. For example, animals with dietary iron overload (93) or systemic inflammation (97) have higher hepatic hepcidin mRNA levels, whereas animals subjected to hypoxia or hemolytic anemia have lower mRNA levels (98,99). Hepcidin is an acute-phase reactant and plays a central role in the hypoferremia of inflammation (i.e., anemia of chronic diseases) (97,100). Hepcidin acts to decrease the functional activity of the iron exporter ferroportin by binding to it and causing its internalization and degradation (101). In the duodenal enterocyte, this leads to decreased basolateral iron transfer and, therefore, decreased dietary iron absorption.

▪ Figure 36.2 Algorithm for the evaluation of possible hereditary hemochromatosis in a person with a negative family history. ALT, alanine aminotransferase; AST, aspartate aminotransferase; wt, wild type.

Dysregulation of hepcidin expression is thought to play a key role in the pathogenesis of HH. Bridle et al. (12) demonstrated that patients with HFE-related HH have low hepatic expression of hepcidin, as do HFE knock-out mice, despite excess hepatic iron stores (12,102,103). Overexpression of hepcidin in HFE knock-out mice prevents the HH phenotype (104). Although technical problems have hindered the measurement of the mature hepcidin peptide in serum, urinary hepcidin concentrations can be determined. Urinary hepcidin levels are low in patients with HH caused by mutations in HFE, TFR2, and HJV (97,105,106,107,108). Therefore, it is proposed that low circulating levels of hepcidin in these forms of HH cause increased ferroportin-mediated efflux of iron from both RE cells (resulting in iron sparing) and duodenal enterocytes (resulting in increased iron absorption). P.1048 The molecular mechanisms by which hepcidin expression is regulated by body iron status

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have not been determined. However, it is hypothesized that TFR2 in hepatocytes may act as an iron “sensor” (24,109). Mutations of TFR2 cause a rare form of HH in humans (24,25) and TFR2-mutant mice have a HH phenotype (110). Despite hepatic iron loading, hepcidin expression is low in patients with TFR2-related HH (108) and in TFR2-mutant mice (111). This suggests that TFR2 is necessary for the appropriate transduction of the signal between body iron status and hepcidin expression (24,109). It has been proposed that hepatocytes may modulate hepcidin expression by sensing the circulating levels of diferric transferrin. The concentration of diferric transferrin in portal blood reflects the rate of iron absorption. The binding of diferric transferrin to TFR2 on hepatocytes might transduce a signal that modulates the expression of hepcidin. Likewise, HFE protein and hemojuvelin may participate in this signaling pathway within hepatocytes because inactivating mutations of both these proteins result in low hepcidin expression and iron overload (24,109). HFE protein binds avidly to the classic transferrin receptor 1 (112), but it is not yet clear whether this interaction plays a part in the signaling pathway to hepcidin. Although the hepatocyte is a strong candidate as the cell type requiring HFE protein for a normal hepcidin response to iron status, some evidence suggests that HFE expression by Kupffer cells may also play a role in the regulation of hepcidin expression. For example, hepatocytes in culture do not respond to changes in iron content with an increase in hepcidin expression (97,113), raising the possibility that another cell type is needed for functional iron sensing. Indeed, HFE knock-out mice demonstrate improved iron status after their Kupffer cells are repopulated using transplanted bone marrow from mice with wild-type HFE (114). While it is clear that dysregulation of hepcidin is central to the pathogenesis of HFErelated HH, HFE may also be able to influence body iron homeostasis independent of hepcidin. It has been shown that transfection of HFE into cultured cells directly influences their iron status (115). Possibly, loss of functional HFE protein in certain cell types (e.g., duodenal crypt cells) could directly contribute to the iron homeostasis abnormalities observed in HFE-related HH. Duodenal crypt cells express HFE protein and have been proposed to act as sensors of body iron status through the uptake of plasma diferric transferrin (116). In support of this concept, the duodenal uptake of plasma iron is impaired in HFE knock-out mice (117). This observation supports the possibility that functional loss of HFE protein may decrease the iron pool in duodenal crypt cells, resulting in a relatively iron-deficient state in these cells. This could cause increased expression of iron transporter genes in daughter villus enterocytes and lead to increased dietary iron absorption. Although this “crypt cell hypothesis” was proposed to try to explain the excess dietary iron absorption in HFE-related HH (116,118), the effect of HFE protein on liver hepcidin expression appears to be paramount.

Non–HFE-Related Hereditary Hemochromatosis Although HFE mutations account for the vast majority of HH, other forms of HH have been recognized and are generally grouped together as non–HFE-related HH (119) (Table 36.1). Mutations in two different genes, HJV and HAMP, cause forms of juvenile HH. The HJV gene encodes hemojuvelin, a glycosylphosphatidylinositol-anchored protein that has substantial expression in hepatocytes. More than 25 disease-causing mutations have been described in HJV (20). Hemojuvelin may be involved in regulating the hepcidin pathway because patients with HJV-associated HH (107) and HJV knock-out mice (120,121) have low hepcidin expression that may be responsible for increased iron absorption. Inactivating mutations of the HAMP gene (that encodes hepcidin) also produce a form of juvenile HH (21). Two distinct types of ferroportin mutations cause autosomal dominant HH (122,123). The first type of mutation results in ferroportin inactivation, while the second type interferes with the interaction between ferroportin and hepcidin (but ferroportin retains its iron export capability). Inactivating ferroportin mutations cause a cellular distribution of iron loading that differs from that of HFE-related HH because iron is retained primarily in RE cells rather than hepatocytes (124). Moreover, TS values tend to be lower than that in HFE-related HH. Individuals with the second type of ferroportin mutation fail to respond to

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hepcidin and therefore demonstrate a more classical HH phenotype. In both forms of ferroportin-related HH (unlike other types of HH), hepcidin expression is elevated rather than decreased (124). Mutations in the TFR2 gene produce an autosomal recessive type of HH that is clinically similar to HFE-related HH (24,25). It is not yet known how these uncommon mutations of TFR2 result in iron overload, but it is possible that they cause abnormal iron sensing by hepatocytes, the predominant site of TFR2 expression (109). DMT1 mediates iron uptake at the intestinal brush border and across the membrane of acidified endosomes in cells such as erythyroid precursors (125,126). A single patient with severe hypochromic microcytic anemia and iron overload has been reported to carry P.1049 a homozygous mutation (E399D) of DMT1 (26). Cell biology studies suggest that E399D DMT1 protein has a partial loss of function that may limit iron availability to erythyroid precursor cells. The resulting anemia may subsequently stimulate dietary iron absorption, mediated by the partially functional DMT1 in enterocytes (127). This may explain the distinguishing iron overload seen in this patient, along with microcytic anemia. Ferritin, which is composed of H and L subunits, plays an important role in iron storage and intracellular iron distribution. Synthesis of both ferritin subunits is controlled by an iron-regulatory protein, which binds to the IRE in the 5′-untranslated region of the H- and L-ferritin mRNAs (128). Kato et al. (27) identified a single point mutation (A49U) in the IRE motif of H-ferritin mRNA in four members of a Japanese family affected by dominantly inherited iron overload. When the mutated H-ferritin mRNA is expressed in cultured cells, there is an increase in iron uptake, suggesting that the A49U mutation may be responsible for tissue iron deposition.

Clinical Features of Hereditary Hemochromatosis In older series of patients with typical phenotypic HH, a number of symptoms and physical findings generally associated with the disorder have been delineated (Tables 36.3, 36.4). Symptoms include fatigue, malaise, abdominal pain, arthralgias, and impotence. Physical findings include hepatomegaly, skin pigmentation, diabetes, and cardiac abnormalities (8,129,130). All physicians should be aware of this constellation of symptoms and findings, but most patients who now come to medical attention have few of these signs or symptoms. More recent series in which patients were identified by family studies, abnormal iron study results on routine screening chemistry panels, or population surveys indicate that most patients are asymptomatic, even on specific questioning about the symptoms of HH (131,132). When symptoms are present, they are the same as those described above, with fatigue and arthralgias being the most common. Therefore, in the face of abnormal iron study results, clinicians should not expect to see the usual symptoms or findings of “classic” HH but should recognize that many C282Y homozygotes are asymptomatic. Alcohol and chronic hepatitis C are potentiating factors in the development of hepatic fibrosis in patients with HFE-related HH (133,134,135).

Table 36.3. Symptoms in Patients with Hereditary Hemochromatosis

ASYMPTOMATIC Abnormal serum iron study results on routine screening chemistry panel Evaluation of abnormal liver test results Identified by family screening Identified by population screening NONSPECIFIC, SYSTEMIC SYMPTOMS Weakness Fatigue Lethargy

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Apathy Weight loss SPECIFIC, ORGAN-RELATED SYMPTOMS Abdominal pain (hepatomegaly) Arthralgias (arthritis) Diabetes (pancreas) Amenorrhea (cirrhosis) Loss of libido, impotence (pituitary, cirrhosis) Congestive heart failure (heart) Arrhythmias (heart)

Table 36.4. Physical Findings in Patients with Hereditary Hemochromatosis

ASYMPTOMATIC No physical findings Hepatomegaly SYMPTOMATIC Liver Hepatomegaly Cutaneous stigmata of chronic liver disease Splenomegaly Liver failure: Ascites, encephalopathy Joints Arthritis Joint swelling Heart Dilated cardiomyopathy Congestive heart failure Skin Increased pigmentation Endocrine Diabetes Testicular atrophy Hypogonadism Hypothyroidism

Diagnosis of Hereditary Hemochromatosis Once the diagnosis of HH is being considered for a patient after either an evaluation of the symptoms and findings listed in Tables 36.3 and 36.4 or a workup for abnormal results of screening iron studies or a family study, then a definitive diagnosis is relatively P.1050 straightforward (133,134,135). The fasting TS (serum iron level divided by transferrin level or total iron-binding capacity, multiplied by 100) and the serum levels of ferritin and liver enzymes should be determined (Table 36.5). It is important that the TS be obtained in the fasting state because the serum iron level varies diurnally, and many breakfast cereals that are highly fortified with iron can raise the serum iron level shortly after ingestion. An elevated TS (≥45%) is recognized as the most common early phenotypic marker of HH; some patients who are homozygous for the C282Y mutation have elevated TS with a normal ferritin level. The sensitivity and specificity of these tests are difficult to determine when young persons are being evaluated (in whom increased iron stores may

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not have developed) or when patients have comorbidities, such as chronic liver disease (in which values may be “falsely” elevated). For example, serum ferritin levels are elevated in more than 50% of patients with alcoholic liver disease (136,137), nonalcoholic steatohepatitis (NASH) (138), or chronic viral hepatitis (139,140,141) in the absence of HH. Furthermore, other inflammatory disorders (e.g., inflammatory arthropathies) and various neoplastic disorders (e.g., lymphoproliferative disorders) may cause ferritin levels to rise without any increase in iron stores. Therefore, many results of serum iron studies can be false-positive or false-negative, and reliance on these laboratory values alone may cause significant problems in the diagnosis. The use of HFE mutation analysis significantly improves diagnostic accuracy in these challenging patients. When evaluating the results of HFE genotyping obtained from screening family members or from population studies, it is valuable to remember that the C282Y mutation has incomplete penetrance. This is highlighted by the results of two large North American population studies comprising approximately 100,000 and 41,000 primary care patients (38,39). In these two populations, a substantial proportion (27% and 60%, respectively) of female C282Y homozygotes had a TS of less than 45% or 50%, respectively, while the values were smaller (16% and 25%, respectively) for male C282Y homozygotes, with a TS of less than 50%. Similarly, more than 40% of female C282Y homozygotes (43% and 46%, respectively) in these populations had serum ferritin levels in the normal range (90%) becomes α 1 -AT negative as the mouse ages. This probably represents the selective proliferation of the globule-devoid hepatocytes, the progenitor cells. Adenomas and then carcinomas arise in these regions in greater than 80% of the mice. This paradigm also appears to apply to the predilection for hepatic cancer in several other forms of chronic liver disease (154). Further understanding of how hepatocytes respond to the accumulation of α 1 -ATZ in the ER is likely to provide more clues about the pathogenesis of this liver disease.

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Hidvegi et al. have used cell line and transgenic mouse models with inducible expression of mutant α 1 -ATZ, which are ideally suited for elucidating the signal transduction pathways that are activated and for determining how they may protect from, or contribute to, liver damage (155). So far these studies have shown that accumulation of the mutant protein in the ER of the model systems does not activate the unfolded protein response but does activate autophagy, nuclear factor κB (NFκB), ER-caspases and BAP31, an ER protein that appears to be involved in the proapoptotic effects of ER on mitochondria. The latter may be the mechanism by P.1077 which mitochondrial damage and mitochondrial caspases are activated in the liver in α 1 -AT deficiency. The rest of this signaling profile is also consistent with the conceptual model of the globule-containing hepatocytes as “sick but not dead” (154).

Diagnosis Diagnosis of α 1 -AT deficiency is established by means of serum α 1 -AT phenotype determination in isoelectric focusing or by means of agarose electrophoresis at acid pH. Serum concentrations can be used for screening, with follow-up PI typing of any values below normal (85 to 215 mg/dL). A retrospective study of all pediatric patients who had both serum concentrations and PI typing done at one center indicated that the serum concentration determination had a positive predictive value of 94% and a negative predictive value of 100% for homozygous α 1 -AT deficiency (156). However, because of the inherent limitations of retrospectively defining a patient population for the analysis, the results of the study are not necessarily applicable to each diagnostic situation that might be encountered. It is wise to get a phenotype together with the serum level in most cases of neonatal hepatitis or unexplained chronic liver disease in older children, adolescents, and adults. Serum concentrations of α 1 -AT may be helpful, when used with the phenotype, to differentiate persons homozygous for the Z allele from SZ compound heterozygotes, both of whom may develop liver disease. In some cases, phenotype determinations of parents and other relatives are necessary to ensure the distinction between ZZ and SZ allotypes, a distinction important for genetic counseling. Serum concentrations of α 1 -AT are occasionally misleading. For example, serum α 1 -AT concentrations may increase during the host response to inflammation, even in homozygous PIZZ individuals and give a falsely reassuring impression. The distinctive histologic feature of homozygous PIZZ α 1 -AT deficiency, periodic acid–Schiff-positive, diastase-resistant globules in the ER of hepatocytes, substantiates the diagnosis (Fig. 37.6). The presence of these inclusions should not be interpreted as confirming the diagnosis of α 1 -AT deficiency. Similar structures are occasionally found in PIMM individuals with other liver diseases (157). The inclusions are eosinophilic, round to oval, and 1 to 40 µm in diameter. They are most prominent in periportal hepatocytes but may also be present in Kupffer cells and cells of biliary ductular lineage (158). There may be evidence of variable degrees of hepatocellular necrosis, inflammatory cell infiltration, periportal fibrosis, or cirrhosis. There may also be evidence of bile duct epithelial cell destruction, and occasionally there is a paucity of intrahepatic bile ducts.

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▪ Figure 37.6 Histologic appearance of liver biopsy specimen of a patient with homozygous PIZZ α 1 -AT deficiency. Micrograph shows periodic acid–Schiffpositive, diastase-resistant globules in hepatocytes, especially periportal ones, adjacent to a broad band of fibrous tissue (periodic acid–Schiff, diastase, 40× original magnification). (Photomicrograph provided by Dr. C. Coffin, St. Louis, MO.)

Treatment The most important principle in the treatment of patients with α 1 -AT deficiency is avoidance of cigarette smoking, which markedly accelerates the destructive lung disease associated with α 1 -AT deficiency, reduces the quality of life, and significantly shortens the longevity of these patients (2). There is no specific therapy for α 1 -AT deficiency–associated liver disease. Therefore, clinical care largely involves supportive management of symptoms caused by liver dysfunction and prevention of complications. Progressive liver dysfunction and failure in children have been managed with orthotopic liver transplantation, with survival rates approaching 90% at 1 year and 80% at 5 years (159). Nevertheless, a number of PIZZ individuals with severe liver disease, even cirrhosis or portal hypertension, may have a relatively low rate of disease progression and lead a relatively normal life for extended periods. With the availability of living–relateddonor transplantation techniques, it may be possible to treat these patients expectantly for some time. Children with α 1 -AT deficiency, mild liver dysfunction (elevated transaminase levels or hepatomegaly), and without functional impairment may never need liver transplantation. Several studies have shown that a class of compounds called chemical chaperones can reverse the cellular mislocalization or misfolding of mutant plasma membrane, and lysosomal, nuclear, and cytoplasmic proteins, including CFTRΔF508, prion proteins, mutant aquaporin molecules associated with nephrogenic diabetes insipidus, and mutant galactosidase P.1078 A associated with Fabry's disease (160,161,162). These compounds include glycerol, trimethylamine oxide, deuterated water, and 4-phenylbutyric acid (PBA). The author and his colleagues have found that glycerol and PBA mediate a marked increase in the secretion of α 1 -ATZ in a model cell culture system (163). Oral administration of PBA was also well tolerated by PIZ mice (transgenic for the human α 1 -ATZ gene) and

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consistently mediated an increase in blood levels of human α 1 -AT, reaching 20% to 50% of the levels present in PIM mice and healthy humans. PBA did not affect the synthesis or intracellular degradation of α 1 -ATZ. The α 1 -ATZ secreted in the presence of PBA was functionally active, in that it could form an inhibitory complex with neutrophil elastase. Because PBA has been used safely for years as an ammonia scavenger to treat children with urea cycle disorders and because results of clinical studies have suggested that only partial correction of the deficiency state is needed for the prevention of both liver and lung injury in α 1 -AT deficiency (164), PBA is an excellent candidate for the chemoprophylaxis of target-organ injury in α 1 -AT deficiency. It also appears now that several iminosugar compounds may be useful for chemoprophylaxis of liver and lung disease in α 1 -AT deficiency. These compounds are designed to interfere with oligosaccharide side chain trimming of glycoproteins and are being examined as potential therapeutic agents for viral hepatitis and other types of infection (165,166). The author and colleagues examined several of these compounds to determine the effect of inhibition of glucose or mannose trimming of carbohydrate side chains on the fate of α 1 -ATZ in the ER. They found, to their surprise, that one glucosidase inhibitor, castanospermine (CST), and two αmannosidase I inhibitors, kifunensine (KIF) and deoxymannojirimicin (DMJ), mediated increased secretion of α 1 -ATZ (167). The α 1 -ATZ secreted in the presence of these drugs has partial functional activity. KIF and DMJ are less attractive candidates for chemoprophylactic trials because they delay degradation of α 1 -ATZ and increase its secretion. These drugs, therefore, have the potential to exacerbate susceptibility to liver disease. However, CST has no effect on the degradation of α 1 ATZ and, therefore, may be targeted for development as a chemoprophylactic agent. The mechanism of action of CST on α 1 -ATZ secretion is not yet known. An interesting hypothesis for the mechanism of action of KIF and DMJ is that mutant α 1 -ATZ interacts with ERGIC-53 for transport from ER to Golgi apparatus when mannose trimming is inhibited. Patients with α 1 -AT deficiency and emphysema have undergone replacement therapy with α 1 -AT purified from recombinant plasma and administered intravenously or by means of intratracheal aerosol (40). This therapy is associated with improvement in α 1 -AT serum concentrations and in α 1 -AT and neutrophil elastase inhibitory capacity in bronchoalveolar lavage fluid without significant side effects. Although results of initial studies have suggested that there is a slower decline in forced expiratory volume in patients undergoing replacement therapy, this occurred only in a subgroup of patients, and the study was not randomized (168). This therapy is designed for persons with established and progressive emphysema. Protein replacement therapy is not being considered for patients with liver disease because there is no information to support the notion that deficient serum levels of α 1 -AT are mechanistically related to liver injury. A number of patients with severe emphysema from α 1 -AT deficiency have undergone lung transplantation in the last 10 years. The latest data from the St. Louis International Lung Transplantation Registry show that 91 patients with emphysema and α 1 -AT deficiency underwent single or bilateral lung transplantation by 1993. The actuarial survival rate among patients in this category who underwent transplantation between 1987 and 1994 was approximately 50% for 5 years. Lung function and exercise tolerance were significantly improved (169). Replacement of α 1 -AT by means of somatic gene therapy has been discussed in the literature (40). This strategy is potentially less expensive than replacement therapy with purified protein and can alleviate the need for intravenous or inhalation therapy. Again, this form of therapy will be useful only in ameliorating emphysema because liver disease associated with α 1 -AT deficiency is not caused by deficient

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levels of α 1 -AT in the serum or tissue. Of course, it would be helpful to know whether replacement therapy with purified α 1 -AT, as it is currently applied, is effective in ameliorating emphysema in this deficiency before embarking on clinical trials involving gene therapy. There are still major issues that must be addressed before gene therapy becomes a realistic alternative (170). Several novel types of gene therapy, such as repair of mRNA by means of trans-splicing ribozymes (171,172) and chimeric RNA/DNA oligonucleotides (173,174,175), triplex-forming oligonucleotides (176), small fragment homologous replacement (177), or RNA silencing (178,179), are theoretically attractive alternative strategies for the management of liver disease in α 1 -AT deficiency because they would prevent the synthesis of mutant α 1 -ATZ protein and ER retention. Studies have shown that transplanted hepatocytes can repopulate the diseased liver in several mouse models, including a mouse model of a childhood metabolic liver disease called hereditary tyrosinemia (180,181). Stem cells from the bone marrow or pancreas can be used instead of adult hepatocytes (182,183). Replication of the transplanted cells occurs only when there is injury or regeneration in the liver (181). These results P.1079 provide evidence that it may be possible to use hepatocyte transplantation techniques to manage hereditary tyrosinemia and, perhaps, other metabolic liver diseases in which the defect is cell autonomous. For example, α 1 -AT deficiency involves a cell-autonomous defect and would be an excellent candidate for this strategy.

Genetic Counseling Restriction fragment length polymorphisms detected with synthetic oligonucleotide probes (184) and family studies (185) allow prenatal diagnosis of α 1 -AT deficiency. Nevertheless, it is not clear how prenatal diagnosis of this deficiency should be used and how families should be counseled about the diagnosis. The data reviewed earlier indicate that 85% to 90% of individuals with α 1 -AT deficiency do not have evidence of liver disease at 18 years of age and that nonsmoking PIZZ individuals may not develop emphysema or even pulmonary function abnormalities until 60 to 70 years of age. These data could support a counseling strategy in which amniocentesis and abortion are discouraged. The only other data on this subject come from two studies with conflicting results. Results of one study suggested that the incidence of significant liver disease among siblings at risk is 78% (186). The results of the other suggested that the incidence is 21% (11). These studies, however, were retrospective and heavily influenced by bias in ascertainment of patients. The issue will not be resolved until it is studied prospectively, as, for example, in the Swedish population (1).

Population Screening Results of several studies have suggested that population screening for α 1 -AT deficiency would be efficacious. First, there is evidence that knowledge of and counseling about the consequences of α 1 -AT deficiency are associated with a reduced rate of smoking among affected adolescents (187,188). Second, although there was initially some evidence for adverse psychological effects (189), more recent results have indicated that there are no significant negative psychosocial consequences in adults who were informed about their deficiency in a follow-up study after neonatal screening in Sweden (190). These data should give new momentum to reconsider screening programs for α 1 -AT deficiency.


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Eriksson S, Carlson J, Velez R. Risk of cirrhosis and primary liver cancer in α 1antitrypsin deficiency. N Engl J Med 1986;314:736–739. Demonstration of predisposition to cirrhosis and hepatocellular carcinoma in α 1 -AT deficiency. Huntington JA, Read RJ, Carrell RW. Structure of a serpin-protease complex shows inhibition by deformation. Nature 2000;407:923–926. Description of the crystal structure of the α 1 -AT–trypsin complex provides a structural basis for the mechanism of enzyme inhibition by α 1 -AT. Lomas DA, Evans DL, Finch JJ, et al. The mechanism of Z α1-antitrypsin accumulation in the liver. Nature 1992;357:605–607. This is the original description of the tendency for α 1 -ATZ to undergo polymerization. Qu D, Teckman TH, Omura S, et al. Degradation of mutant secretory protein, α1antitrypsin Z, in the endoplasmic reticulum requires proteasome activity. J Biol Chem 1996;271:22791–22795. This paper provides evidence that degradation of α 1 -ATZ in the ER requires interaction with the molecular chaperone calnexin, ubiquitin system, and proteasome. Rudnick DA, Liao Y, An J-K, et al. Analyses of hepatocellular proliferation in a mouse model of α1-antitrypsin deficiency. Hepatology 2004;39:1048–1053. Evidence for increased hepatocellular proliferation and basis for carcinogenesis in α 1 AT deficiency Stein PE, Carrell RW. What do dysfunctional serpins tell us about molecular mobility and disease? Nat Struct Biol 1995;2:96–113. This is a comprehensive review of the structural biochemistry of α 1 -AT, the serpins, and dysfunctional variants of α 1 -AT and the serpins. Sveger T, Eriksson S. The liver in adolescents with α1-antitrypsin deficiency. Hepatology 1995;22:514–517. These are the most recent results of the nationwide screening study of α 1 -AT deficiency initiated in Sweden in the 1970s. It is the only unbiased study of the disease. Teckman JH, An J-K, Blomenkamp K, et al. Mitochondrial autophagy and injury in the liver α1-antitrypsin deficiency. Am J Physiol 2004;286:G851–G862. Evidence for mitochondrial autophagy and injury cell line, transgenic mouse models of α 1 -AT deficiency, and demonstration that cyclosporin A prevents liver injury and mortality. Wu Y, Whitman I, Molmenti E, et al. A lag in intracellular degradation of mutant α1-antitrypsin correlates with the liver disease phenotype in homozygous PIZZ

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α1-antitrypsin deficiency. Proc Natl Acad Sci USA 1994;91:9014–9018. This is the original description of a defect in the degradation of α 1 -ATZ in the ER that predisposes a subgroup of persons with α 1 -ATZ deficiency to liver disease.

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Copyright ©2007 Lippincott Williams & Wilkins > Table of Contents > Volum e 2 > Section V II - Genetics and Metabolic D isease > Ch ap ter 38 - Porphyrias

Chapter 38 Porphyrias Joseph R. Bloomer David A. Brenner

Key Concepts z

The porphyrias are metabolic disorders in which abnormalities in heme biosynthesis cause an excessive accumulation and excretion of porphyrins and porphyrin precursors. A defect in an enzymatic step in the heme biosynthetic pathway is present in each of the porphyrias.

z

The genes that encode the enzymes of the heme biosynthetic pathway have been cloned and sequenced. This has made it possible to identify the gene mutations that cause the enzyme defects and has shown that each of the porphyrias has genetic heterogeneity (i.e., several different mutations have been found).

z

The principal clinical manifestations are photocutaneous lesions, neurologic dysfunction, and structural liver disease. The photocutaneous lesions are caused by the photoactive properties of porphyrins in skin. Neurologic dysfunction, which underlies the acute porphyric attack, is probably caused by a toxic effect of δ-aminolevulinic acid and/or heme deficiency state. Therapy for the acute porphyric attack is designed to stop the factors that precipitate the attack and provide a high carbohydrate diet. Intravenous hematin is administered to restore hepatic heme homeostasis.

z

Liver damage in porphyria cutanea tarda is due to the metabolic abnormality and additional factors, such as alcoholism and hepatitis C infection. Phlebotomy is the first line of therapy.

z

Liver damage in protoporphyria is caused by the toxic effect of protoporphyrin on the liver. Liver transplantation has been carried out successfully in several patients, but protoporphyrin-induced damage may occur in the new liver.

z

Several nonporphyric disorders, particularly those that cause hepatobiliary disease, may be associated with increased urine excretion of coproporphyrin. This is termed secondary porphyrinuria. It can usually be distinguished from the acute porphyrias by measuring the urinary excretion of δ-aminolevulinic acid and porphobilinogen (PBG).

z

Pseudoporphyria describes a condition with clinical and histologic features similar to porphyria cutanea tarda, but with normal or near normal porphyrin levels.

The porphyrias are metabolic disorders that are characterized biochemically by the excess accumulation and excretion of porphyrins and porphyrin precursors. These compounds are intermediates of the heme biosynthetic pathway, and the elucidation of the biochemical features of the porphyrias follows the delineation of this pathway (1). An important milestone in understanding the pathogenesis of the biochemical abnormalities was in 1970, when a deficiency of porphobilinogen(PBG) deaminase activity P.1086 was demonstrated in tissues from patients with acute intermittent porphyria (AIP) (2). Subsequently, an enzyme defect was found for each type of porphyria. During the last decade, the gene mutations that cause the enzyme defects have been identified. The liver and bone marrow are the major sites of heme production and, therefore, are the principal sites of expression of the biochemical abnormalities. This formed the basis for the early classification of the porphyrias as either hepatic or erythropoietic (3). When the hepatic mixed-function oxidase system is induced by the administration of drugs, the amount of heme synthesized in the liver increases and the rate of formation of the porphyrins and porphyrin precursors increases. Therefore, patients with acute hepatic porphyrias may have substantial variation in the biochemical abnormalities because of various factors that affect the rate of hepatic heme biosynthesis. The liver also has an important role in the excretion of porphyrins (4). This causes the liver to be susceptible to the toxic effects of porphyrin accumulation. Conversely, hepatobiliary disease of many types causes an increase in the urinary excretion of porphyrins—in particular, coproporphyrin—because excretion of these compounds is diverted from bile to urine. This condition is called secondary porphyrinuria. The principal clinical manifestations of the porphyrias are caused by their effects on the nervous system, skin, and liver. The diagnosis of a specific type of porphyria can be entertained based on the combination of the clinical features. A noteworthy feature of the porphyrias is the relationship between the clinical manifestations and biochemical abnormalities. The porphyrias associated with acute attacks of neurologic dysfunction are characterized by increased accumulation and excretion of the porphyrin precursors δ-aminolevulinic acid (ALA) and PBG. The porphyrias associated with photocutaneous lesions and liver disease are characterized by increased accumulation of the porphyrin compounds themselves.

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Heme Metabolism Heme Biosynthesis Heme is a member of a group of compounds called tetrapyrroles. These compounds are composed of four pyrrole rings arranged into a larger ring by one-carbon bridges (Fig. 38.1). The four pyrrole nitrogen atoms are oriented toward the center of the ring. Because of the central cavity and the chemical properties of the central nitrogen atoms, tetrapyrroles have excellent metal-binding characteristics. Their complexes with iron (heme), magnesium (chlorophyll), and cobalt (vitamin B 1 2 ) are crucial to living organisms. The iron in heme has four of its six coordination positions occupied by the four tetrapyrrole nitrogen atoms. The remaining two coordination positions may be occupied by heteroatoms on the side chains of proteins or by solvent or solute molecules, which, in turn, affect the chemical properties of the iron. The chemistry of the heme moiety is therefore dictated by its protein microenvironment and the nature of the fifth and sixth ligands to iron. Hemoproteins have a variety of chemical interactions, including oxidation–reduction reactions, activation of oxygen, and ligand binding (e.g., oxygen transport). Hepatic hemoproteins include mixed-function oxidases (e.g., cytochrome P-450), dioxygenases (e.g., prostaglandin cyclo-oxygenase), catalase, peroxidases, and tryptophan pyrrolase, all of which are involved in the modification or catabolism of endogenous substrates or potentially toxic compounds. Heme also serves as the oxidation–reduction center for the cytochromes of mitochondrial electron transport and the smooth endoplasmic reticulum. Heme is synthesized in mammalian tissues in eight steps that are under enzymatic control (Fig. 38.2). In the first step, ALA is formed by the condensation of succinyl-CoA with glycine (5,6). The reaction is catalyzed by the enzyme ALA synthase and occurs in the mitochondrial matrix. Pyridoxal phosphate is required as a cofactor. ALA diffuses into the cytoplasm of the cell, where two molecules are condensed in a side-to-side manner by the action of ALA dehydrase (7). The product is the monopyrrole PBG. Four molecules of PBG are then joined head to tail, with the displacement of four amino groups through a reaction catalyzed by PBG deaminase, forming the linear tetrapyrrole hydroxymethylbilane (8,9). Dipyrromethane, which is made from PBG by the same enzyme, is a critical cofactor in the reaction. Hydroxymethylbilane spontaneously forms the cyclic compound, uroporphyrinogen I. Porphyrinogens are structures comprising four pyrrole units joined by methylene (–CH 2 –) groups; they are nonplanar and nonaromatic. Each pyrrole unit of uroporphyrinogen I has an acetate and a propionate side chain that alternate strictly. Enzymic formation of cyclic hydroxymethylbilane is catalyzed by uroporphyrinogen III synthase (also called cosynthase) (10,11). This alters the symmetry by reversing the sense of the last pyrrole unit (the D ring). The order of side chains after enzymic cyclization beginning with group R1 (Fig. 38.1) is acetate–propionate (A ring), acetate–propionate (B ring), acetate–propionate (C ring), propionate– acetate (D ring). Uroporphyrinogen decarboxylase (uroporphyrinogen carboxylase) is a cytosolic enzyme that catalyzes the stepwise decarboxylation of each of the acetate side chains of uroporphyrinogen, leaving methyl substituents (12,13). It is a unique decarboxylating P.1087 enzyme in that no cofactors or coenzymes are involved. The enzyme is active with both uroporphyrinogen I and III but not with the oxidized form of the substrate, uroporphyrin. During the course of the decarboxylation, intermediates having seven, six, and five carboxyl groups are generated and are referred to as hepta-, hexaand pentacarboxylate porphyrinogens, respectively. The final product of the reaction is the tetracarboxylate coproporphyrinogen.

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▪ Figure 38.1 Structures of the porphyrin precursors δ-aminolevulinic acid, porphobilinogen (PBG), porphyrin, and heme. All porphyrins have the same tetrapyrrole ring structure, but they differ in the composition of side chains (R1 to 8) attached to the ring. Uroporphyrin has eight carboxylic acid side chains, coproporphyrin has four, and protoporphyrin has two. Porphyrinogens are the reduced forms of the porphyrins, in which the methene bridges linking the four pyrrole groups are replaced by methylene groups.

The next step is catalyzed by coproporphyrinogen oxidase. The propionate side chains at R2 and R4 of coproporphyrinogen III are oxidatively decarboxylated, forming the vinyl (–CH=CH 2 ) substituents of protoporphyrinogen IX (14). The enzyme, which is located between the outer and inner mitochondrial membranes (15), is active only with coproporphyrinogen III; no other isomer serves as substrate. Protoporphyrinogen IX undergoes a six-electron oxidation catalyzed by protoporphyrinogen oxidase (16). In mammalian liver, the reaction requires molecular oxygen as the final electron acceptor, but the primary electron acceptor and electron pathway to oxygen are unknown. The enzyme is located in the inner mitochondrial membrane (17). The final step in heme biosynthesis involves the insertion of divalent (ferrous) iron into protoporphyrin IX, forming heme; the reaction is catalyzed by ferrochelatase (18), which is located on the matrix side of the inner mitochondrial membrane (19). Human ferrochelatase contains a [2Fe–2S] cluster that is essential for activity (20). The enzyme is active with other dicarboxylic porphyrin substrates and with other divalent metal ions, such as Co 2 + and Zn 2 + ; it is not active with trivalent metals [e.g., Fe 3 + or Co 3 + ]. Its functional state is a homodimer, as revealed by its crystal structure (21).

Hepatic Heme Metabolism The synthesis of heme in liver is controlled primarily by the level of ALA synthase activity, which is, in turn, controlled by a regulatory heme pool through negative feedback inhibition (Fig. 38.3). Two forms of ALA synthase—erythroid and nonerythroid—are encoded by different genes (22). The nonerythroid or housekeeping form of the enzyme, which is present P.1088 in the liver, is induced by a variety of chemicals. Heme controls hepatic ALA synthase activity by repressing the synthesis of the enzyme and also by inhibiting its transport from the cytoplasm into mitochondria (23,24). The synthesis is repressed by a decrease in the level of ALA synthase messenger ribonucleic acid (mRNA) (25,26). A heme regulatory motif in the enzyme has been implicated in the inhibition of its transport into mitochondria (27).

▪ Figure 38.2 Heme biosynthetic pathway, illustrating the enzyme abnormalities that characterize the different types of porphyria. Heme biosynthesis is distributed between the mitochondria and cytoplasm of the cell, as shown. ALA, δ-aminolevulinic acid.

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▪ Figure 38.3 Control of hepatic heme biosynthesis. Under basal conditions, the rate-limiting enzyme in the pathway, δ-aminolevulinic acid (ALA) synthase, is under negative feedback control by a putative regulatory heme pool. An increased demand for hepatic heme biosynthesis, as occurs when there is formation of more cytochrome P-450 or other hemoproteins, may deplete this pool. This removes the negative feedback control and causes induction of ALA synthase and thereby increases the synthesis of porphyrins and porphyrin precursors.

It is estimated that, in humans, the liver accounts for approximately 15% to 20% of the total body production of heme (28). Most heme produced in the hepatocyte enters the hepatic hemoprotein pool. Because heme is formed at the inner mitochondrial membrane, it must be distributed to apoproteins throughout the hepatocyte for hemoprotein activity to be constituted. A heme-binding protein in liver cytosol, which appears to be identical to the liver fatty-acid–binding protein, may have a role in the efflux of heme from mitochondria (29). The microsomal cytochrome P-450 system utilizes most of the hepatic heme, accounting for more than 60%. Other hemoproteins—such as cytochrome b 5 , the mitochondrial cytochromes, and catalase—also have critical functions in the liver. Heme is catabolized to bilirubin through the combined actions of microsomal heme oxygenase and biliverdin reductase (30,31,32). Heme oxygenase is found in both hepatocytes and Kupffer cells, the latter having high activity. Heme oxygenase opens the heme ring, releasing carbon monoxide and iron in the process, to form the green pigment biliverdin. Biliverdin is then reduced by biliverdin reductase to form bilirubin. Because the hepatocyte has heme oxygenase activity, it can degrade the heme that it produces. Most of the heme that is degraded comes from the functional hemoprotein pool, but a portion of newly formed heme is catabolized to bilirubin before it is incorporated into hemoproteins (33). Some hepatic heme is degraded P.1089 through a pathway that does not form carbon monoxide and bilirubin (34). Hepatic heme oxygenase is a heat-shock protein that is induced by stimuli that cause oxidative stress (30,35), suggesting that it may have a role in the response to hepatic injury. Heme oxygenase may additionally modulate hepatic vascular perfusion through the production of carbon monoxide (36), which causes smooth muscle relaxation.

Biliary Excretion of Heme Isolated hepatocytes secrete newly synthesized heme into the culture medium (37). There is no evidence that heme synthesized in the liver of the intact organism is secreted into the blood, but studies in the bile fistula of animals and humans indicate that heme is excreted in bile (38,39). Heme excreted in bile does not enter the enterohepatic circulation because heme is catabolized by the mucosal cells of the intestine. In healthy subjects, the fractional absorption of radioactive iron from food containing inorganic iron salts is 1%, compared with 16% from food containing iron in hemoglobin (40). Microsomal heme oxygenase activity in the intestinal mucosa is at a level similar to that in the liver and spleen; this increases significantly in animals made iron deficient (40). Therefore, heme excreted in bile is absorbed by mucosal cells in the intestine, where heme oxygenase catalyzes its cleavage to release inorganic iron for use in the body.

Excretion of Porphyrins and Porphyrin Precursors The excretory routes of porphyrins and porphyrin precursors are determined primarily by the solubility of the compounds: Water-soluble compounds are excreted in the urine, whereas water-insoluble compounds are excreted in bile. The porphyrin precursors ALA and PBG are soluble in aqueous solution and are excreted in urine. Uroporphyrin is also water soluble because of the presence of eight carboxyl groups and is excreted

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predominately in urine. Protoporphyrin, which has only two carboxyl groups, is poorly water soluble and is excreted almost entirely in bile. Coproporphyrin has four carboxyl groups and is excreted in both bile and urine, with the symmetric coproporphyrin I isomer being preferentially excreted in bile. When hepatobiliary disease occurs, biliary excretion of coproporphyrin diminishes and urinary excretion increases. Therefore, hepatobiliary disease is a cause of increased coproporphyrin excretion in the urine, a condition termed secondary porphyrinuria. The porphyrinogens are excreted in a pattern similar to their corresponding porphyrins, except that coproporphyrinogen is excreted in a proportionately greater amount in urine than is coproporphyrin. Unlike bilirubin, none of the porphyrinogens or porphyrins is conjugated before excretion. In healthy individuals, the predominant porphyrin in bile is coproporphyrin, with small amounts of protoporphyrin and negligible amounts of uroporphyrin (41,42). Protoporphyrin and other 2-, 3-carboxyl porphyrins are predominant in feces. Therefore, most of the protoporphyrin in normal stool is probably derived from bacterial metabolism and ingested food (43). The mechanism by which the liver excretes protoporphyrin into bile has been investigated extensively in isolated perfused rat liver (44,45,46). In this system, the uptake of protoporphyrin from the perfusing medium occurs by simple or facilitated diffusion and continues at a significant rate, even when excretion into bile is impaired. Intracellular transport is not inhibited by colchicine or monensin, indicating that nonvesicular carriers are targeted to the canalicular membrane. Bile acids facilitate the excretion of protoporphyrin into bile, primarily by increasing the concentration of protoporphyrin that can be attained rather than by increasing bile flow. This is related to the structure of the bile acid. Cholate increases the biliary excretion of protoporphyrin more than that of chenodeoxycholate, which, in turn, has a greater effect than ursodeoxycholate. Secretion of protoporphyrin into bile appears to be mechanistically linked to the secretion of phospholipid (46). An mdr P-glycoprotein is essential for biliary phospholipid excretion (47), translocating phospholipid from the inner to the outer canalicular membrane leaflet. Protoporphyrin secretion into bile after a protoporphyrin load is reduced by 90% in mice that are homozygous for disruption of the mdr2 P-glycoprotein (48).

Biochemical Abnormalities in the Porphyrias Enzyme Defects Each of the eight types of porphyrias is associated with an enzyme defect in the heme biosynthetic pathway that produces a characteristic pattern of abnormal accumulation and excretion of porphyrins and/or porphyrin precursors (Fig. 38.2; Table 38.1) (2,49,50,51,52,53,54,55,56,57,58,59,60,61,62). For example, the deficiency of PBG deaminase activity in AIP causes the excess accumulation and excretion of ALA and PBG, whereas a deficiency of ferrochelatase activity in protoporphyria causes the excess accumulation and excretion of protoporphyrin. The diagnosis of a specific porphyria is made by documenting the pattern of abnormal porphyrin and/or porphyrin precursor P.1090 excretion that is characteristic for that type of porphyria. In some types, the diagnosis may be confirmed by demonstrating a deficiency of activity for the enzyme that leads to the biochemical abnormality. This has been most effectively applied to the measurement of erythrocyte PBG deaminase activity to diagnose AIP (Fig. 38.4) (63,64). However, approximately 5% of patients with AIP have a splicing mutation in which normal erythrocyte PBG deaminase activity is preserved (65).

Table 38.1. Biochemical Features of the Porphyrias

Type of porphyria Acute intermittent

Enzyme defect PBG deaminase

Major site of

Principal

Chromosome

biochemical

biochemical

location

abnormality

features

11q23.3

Liver

porphyria

Variegate porphyria

ALA and PBG in urine

Protoporphyrinogen

1q22

Liver

oxidase

ALA, PBG, and coproporphyrin in urine; protoporphyrin in feces

Hereditary

Coproporphyrinogen

coproporphyria

oxidase

3q12

Liver

ALA, PBG, and coproporphyrin in urine; coproporphyrin in feces

ALA dehydrase

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ALA dehydrase

9q34

Liver

ALA in urine

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deficiency

Porphyria cutanea

Uroporphyrinogen

tarda

decarboxylase

1p34

Liver

Uroporphyrin in urine; isocoproporphyrin in feces

Hepatoerythropoietic

Uroporphyrinogen

porphyria

decarboxylase

1p34

Liver and

Zinc protoporphyrin

bone

in red cells;

marrow

uroporphyrin in urine; isocoproporphyrin in feces

Congenital

Uroporphyrinogen

10q25.2

Bone

Uroporphyrin in red

erythropoietic

III synthase

q26.3

marrow

cells and urine;

porphyria

coproporphyrin in feces

Protoporphyria

Ferrochelatase

18q21.3

Bone

Protoporphyrin in

marrow

red cells, bile and

(liver

feces

variable)

PBG, porphobilinogen; ALA, δ-aminolevulinic acid.

Some of the porphyrias (e.g., AIP, hereditary coproporphyria, and variegate porphyria) have a marked increase in the level of hepatic ALA synthase activity during acute exacerbations of the disease (i.e., acute porphyric attack) (2,66). The increased demand for hepatic heme biosynthesis depletes the regulatory heme pool and thereby removes the negative feedback control on ALA synthase (Fig. 38.3). In AIP, the increased hepatic production of ALA also causes excess formation of PBG. Because of deficient hepatic PBG deaminase activity, ALA and PBG accumulate in greater amounts than they do under basal conditions and are excreted in greater amounts in the urine as well (Fig. 38.4). The acute attack abates when sufficient heme is produced to return hepatic ALA synthase activity to normal, and the excretion of ALA and PBG returns to the basal level. Therefore, patients with AIP may have substantial variation in biochemical abnormalities because of various factors that affect the rate of hepatic heme biosynthesis. Variegate porphyria is unique in that protoporphyrinogen, which accumulates because of a defect in protoporphyrinogen oxidase, inhibits PBG deaminase (67). This functionally causes a situation same as that in AIP; therefore, excess amounts of ALA and PBG are formed and excreted in the urine when hepatic ALA synthase activity is induced.

Molecular Pathogenesis of Enzyme Defects The cloning of complementary deoxyribonucleic acid (cDNA) and genes that encode the enzymes of the heme biosynthetic pathway has made it possible to identify the gene mutations that cause enzyme defects; AIP has been the most intensively studied. PBG deaminase activity is usually reduced by approximately 50% in all tissues of patients with this disorder, although for some families the enzyme deficiency is restricted to nonerythropoietic tissues because mutations in exon I selectively affect the nonerythroid form of the enzyme (68,69). More than 200 different mutations have been reported for AIP, demonstrating significant genetic heterogeneity (70,71). These result either in the absence of the protein encoded by the mutant allele or in the synthesis of the protein that has abnormal catalytic properties. The mutations produce abnormal splicing of PBG deaminase mRNA, insertions or deletions in exons that cause premature termination of protein synthesis, nucleotide changes producing stop codons that prevent complete translation of PBG deaminase mRNA, and nucleotide changes causing the substitution of P.1091 an amino acid that affects catalytic activity (70). The prevalence of the different mutations is highly variable among different populations. In the United States, no specific mutation has been predominant, whereas in Sweden, nearly half of the families share the same mutation (72).

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▪ Figure 38.4 Enzyme defect in acute intermittent porphyria (AIP). (Top) Porphobilinogen (PBG) deaminase activity is deficient in tissues of patients with AIP compared with healthy controls and patients with other types of porphyria. (Bottom) As a consequence of deficient PBG deaminase activity, patients with AIP excrete increased amounts of δ-aminolevulinic acid (ALA) and PBG in their urine, particularly when ALA synthase is induced. RBC, red blood cell; nmol Uro/mL, nmol uroporphyrinogen formed per mL red cells. (From Pierach CA, Weimer MK, Cardinal RA, et al. Red blood cell porphobilinogen deaminase in the evaluation of acute intermittent porphyria. JAMA 1987;60:257; with permission.)

Genetic heterogeneity has also been found in other types of porphyria. This includes the rare types, such as ALA dehydrase deficiency. The mechanism for variegate porphyria among South Africans is unique in that more than 90% of patients with the disorder have the same mutation in the protoporphyrinogen oxidase gene (73). This strongly supports the founder hypothesis that has been proposed for variegate porphyria in South Africa. Sporadic porphyria cutanea tarda (PCT) may be an exception to the “rule” that gene mutations are responsible for deficient enzyme activity. Mutations in uroporphyrinogen decarboxylase cDNA or the promoter region of the uroporphyrinogen decarboxylase gene have not been identified, which suggests that sporadic PCT is not caused by mutations at the uroporphyrinogen decarboxylase locus (74). If other inherited factors are responsible for the pathogenesis of human sporadic PCT, the findings in animal models of the disorder may be relevant. In these models, the differences in the expression of liver-specific cytochrome P-450 compounds that generate inhibitors of uroporphyrinogen decarboxylase are inherited (75,76). Inheritance of a hemochromatosis gene mutation may also increase the susceptibility for sporadic PCT (77,78). However, there has been no clear-cut relationship between specific mutations in porphyric disorders and the severity of clinical and biochemical manifestations. P.1092 This is not surprising because clinical expression of a disease is quite variable, even among members of a family. It means that identification of a specific mutation in an individual at an early age probably cannot be used to predict the severity of disease expression. DNA analysis has not become an established method of diagnosing porphyria. Because of genetic heterogeneity, it may not be a practical way to establish the diagnosis initially, except in geographical areas where a specific mutation has a high prevalence. In a patient with a known mutation, however, DNA analysis should be the method of choice for evaluating family members (71).

The Acute Porphyrias Three of the porphyrias—AIP, variegate porphyria, and hereditary coproporphyria—are characterized by episodic attacks of neurologic dysfunction, the so-called acute porphyric attack (Table 38.2). These are inherited as autosomal dominant disorders. Porphyric attacks also occur in ALA dehydrase deficiency porphyria, which is inherited as an autosomal recessive disorder (See “Rare Types of Porphyria”). In 1955, Berger and Goldberg proposed the name hereditary coproporphyria for a disorder characterized by

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acute episodes of neurologic dysfunction accompanied by elevation of urinary ALA and PBG levels. Unlike patients with the previously described porphyrias, these patients had a marked increase in the urinary and fecal excretion of coproporphyrin (88,89). They also had dermatologic lesions. The disorder is much less common than AIP.

Table 38.2. Clinical Features of the Porphyrias

Structural Usual

Neurologic

Photocutaneous

liver

Hepatocellular

inheritance

dysfunction

lesions

disease

carcinoma

AD

+

-

-

+

Variegate porphyria

AD

+

+

-

+

Hereditary

AD

+

+

-

-

AR

+

-

-

-

Porphyria cutanea

AD

-

+

+

+

tarda

(familial

AR

-

+

±

-

AR

-

+

-

-

AD

-

+

+

-

Type of porphyria Acute intermittent porphyria

coproporphyria

ALA dehydrase deficiency

type)

Hepatoerythropoietic porphyria

Congenital erythropoietic porphyria

Protoporphyria

ALA, δ-aminolevulinic acid; AD, autosomal dominant; AR, autosomal recessive; +, present; –, absent.

P.1093

Clinical Features of the Acute Porphyric Attack The clinical features of the porphyric attack are similar for each of the acute porphyrias (Table 38.3) (90), although they tend to be worse in AIP. The severity of an episode depends in part on how much neurologic damage occurred before appropriate intervention was instituted. Women more frequently have acute attacks and appear to have more severe attacks. The episodes may be precipitated by the use of medications (Table 38.4) and by periods of fasting. For some women, attacks occur regularly just before menses, suggesting the importance of female hormones. However, pregnancy is well tolerated by most patients (91). Abdominal pain is nearly always present. It is caused by autonomic nerve dysfunction. The pain is colicky in nature and often localized to the lower quadrants. An abdominal examination reveals decreased or absent bowel sounds, and abdominal x-rays show alternating areas of spasm and dilatation in the bowel. Pain is relieved by ganglionic blockade; a postmortem study showed destruction of visceral nerve myelin sheaths (92,93). The patients also complain of nausea, vomiting, and constipation or, more rarely, diarrhea. Because there is often an associated leukocytosis, the patient may have to undergo laparotomy for the evaluation of intra-abdominal infection before the diagnosis can be established (90). Other signs and symptoms of autonomic dysfunction include tachycardia and labile hypertension. When these are present, the patient should be monitored carefully because sudden death has been reported (94,95). Fever, bladder distension, disturbed sweating, and postural hypotension may also occur (90,96). The peripheral nervous system has both motor and sensory dysfunction. Motor damage occurs early and involves proximal muscle groups; unlike the Guillain Barré syndrome, it tends to involve the upper extremities first (90,96). Electrophysiologic findings indicate an axonal polyradiculopathy or neuropathy (97). Respiratory paralysis can be life threatening, necessitating intubation with ventilator support. Fortunately, this complication usually occurs late in an attack. Diffuse pain involving the extremities, chest, and back is common. Patients also complain of dysesthesias and paresthesias. Deep tendon reflexes are normal at first but are lost progressively in

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prolonged attacks. Of note, the ankle reflexes may be selectively preserved. Central nervous system involvement is also common (90,96). Increased irritability may be the first indication of an impending attack. Insomnia, anxiety, and behavioral changes develop as the attack continues. The patient may become violent and may be labeled as being hysterical, which, in turn, may lead to taking medications that exacerbate the attack. A psychiatric evaluation may reveal severe depression or paranoia; frank psychosis and hallucinations are also seen. Following the acute attack, chronic psychiatric disorders—especially depression— are seen more frequently than in the general population. Seizures can occur during an acute attack, presenting a difficult clinical problem (90,98,99). Most of the common antiepileptics have a potential for exacerbating the attack. Gabapentin appears to be an exception, presumably because it is not metabolized appreciably P.1094 by the liver in humans (100). Inappropriate secretion of antidiuretic hormone with concomitant hyponatremia has been observed, and hypothalamic lesions have been found at necropsy (101,102). Abnormalities in electroencephalograms can occur in the absence of seizure activity, with nonspecific slowing being the most common. Progressive somnolence and eventual coma develop during the advanced attack. The mortality for patients with AIP who required hospitalization was three times that of the general population during the last 50 years, with most deaths occurring during a porphyric attack (103). Survival appears to have improved since the advent of hematin therapy in 1971 (103,104).

Table 38.3. Signs and Symptoms in Acute Porphyric Attacks

Signs and symptoms

Occurrence

Autonomic neuropathy

Peripheral neuropathy

Central nervous system involvement

%

Abdominal pain

95

Tachycardia (>100 bpm at rest)

80

Constipation

48

Nausea, vomiting

43

Labile hypertension

36

Postural hypotension

21

Bladder distension

12

Dyshidrosis

12

Fever

9

Fecal impaction

6

Peripheral motor deficit (including respiratory)

60

Extremity pain, paresthesias

50

Back pain

29

Absent reflexes

29

Chest pain

12

Bulbar neuropathy

46

Mental confusion/hallucinations

40

Seizures

20

Coma

10

bpm, beats per minute. From Stein JA, Tschudy DP. Acute intermittent porphyria. A clinical and biochemical study of 46 patients. Medicine 1970;49:1, with permission.

Table 38.4. Drugs and the Porphyrias

Drug Analgesics

Unsafe

Thought to be safe

Antipyrine, oxycodone, pentazocine,

Acetaminophen, aspirin, codeine,

phenacetin

diflunisal, fenoprofen, fentanyl, ibuprofen, indomethacin, methadone, morphine, sulindac

Anesthetics

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Chloroform, enflurane, halothane,

Cyclopropane, ether, nitrous oxide,

isoflurane, lignocaine, prilocaine

propofol, procaine, succinylcholine

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Anticonvulsants

See text

See text

Antimicrobials

Chloramphenicol, dapsone,

Acyclovir, aminoglycosides,

erythromycin, griseofulvin,

amoxicillin, amphotericin, ampicillin,

ketoconazole, miconazole,

ciprofloxacin, flucytosine,

nitrofurantoin, rifampin, sulfonamides,

gentamicin, norfloxacin, ofloxacin,

trimethoprim, doxycycline (Vibramycin)

penicillin, streptomycin, ticarcillin, vancomycin, zidovudine

Cardiovascular

Amiodarone, nifedipine, simvastatin,

Adrenaline, atropine, clofibrate,

drugs

verapamil

digoxin, heparin, procainamide, quinidine, warfarin

Diuretics and

α-Methyldopa, captopril, clonidine,

Acetazolimide, amiloride,

antihypertensives

enalapril, furosemide, hydralazine,

bumetamide, ethacrynic acid,

hydrochlorothiazide, lisinopril,

guanethidine, labetalol, metoprolol,

spironolactone

propanolol, reserpine, timolol, tolazoline

Sedatives and

Alprazolam, amitriptyline, carisoprodol,

Chloral hydrate, chlorpromazine,

tranquilizers

chlordiazepoxide, diazepam,

droperidol, prochlorperazine,

flurazepam, glutethimide, hydroxyzine,

triazolam

imipramine, loxapine, meprobamate

Others

Aminophylline, baclofen, bromocriptine,

Beclomethasone, chlorpheniramine,

busulphan, chlorpropamide,

colchicine, dexamethasone,

cyclosporine, danazol, diclofenac, ergot

famotidine, glucagon, insulin,

compounds, glipizide, methotrexate,

lithium, quinine

metoclopramide, tamoxifen, theophylline, tolbutamide

Moore MR, Hift RJ. Drugs in the acute porphyrias—toxicogenetic diseases. Cell Mol Biol (Noisy-le-grand) 1997;43:89.

Biochemical Evaluation For the undiagnosed patient who presents with signs and symptoms of an acute porphyric attack, it is not critical to identify the specific type of porphyria because therapy is the same for all. The urinary excretion of ALA and PBG should be quantitated because excretion of these compounds is increased in acute porphyrias during the porphyric attack. Sodium carbonate (4 g) should be added to the urine collection bottle to prevent degradation of PBG. Four screening tests can be used to detect increased PBG levels in the urine while proceeding with the quantitative measurement: The Watson-Schwartz test, the Hoesch test, the MauzerallGranick test, and the Trace PBG kit (Thermo Trace/DMA, Arlington, Texas) (105,106,107). All the tests rely on the reaction of PBG with Erlich's reagent in an acidified solution to form a red compound. An expert panel recently recommended the Trace PBG kit, which detects urine PBG concentrations greater than 6 mg/L, to screen for acute porphyria attacks (107). Because urobilinogen also reacts with Erlich's reagent to form a red compound, particular care must be taken in the Watson-Schwartz test to extract the solution with organic solvents so that a false-positive result is avoided. When allowed to stand in the light and air, urine containing excess PBG may also turn black because of the conversion of PBG to porphobilin and other pigments. In a critically ill patient, these screening studies can be used as a basis for beginning therapy. After the diagnosis of acute porphyria is made, the specific type of porphyria can be established by measuring erythrocyte PBG deaminase activity (e.g., AIP), the fecal excretion of protoporphyrin and plasma porphyrin fluorescence pattern (e.g., variegate porphyria), and fecal and urinary coproporphyrin excretion (e.g., hereditary coproporphyria). P.1095

Pathogenesis of the Acute Porphyric Attack The mechanism of the neurologic dysfunction that underlies the acute porphyric attack remains unclear. Several factors may be responsible. The development of mice that are made PBG deaminase deficient by gene targeting may provide a means of sorting out the different possibilities (105,106,107,108). A central role for ALA in the development of the acute attack has been postulated (Fig. 38.5). The level of this compound is increased in blood and urine during an attack of any acute porphyria and normal in the porphyrias

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without neurologic crises. Also, in hereditary tyrosinemia and lead intoxication, a marked elevation in ALA level is associated with neurologic features that are indistinguishable from those in the acute porphyrias (109,110,111,112). ALA is structurally similar to γ-aminobutyric acid (GABA), the major inhibitory neurotransmitter in the central nervous system (113). It is a potent GABA receptor agonist (114,115); the interaction of ALA with this receptor may be responsible for some of the symptoms in the acute attack. Intraventricular injection of ALA in experimental animals results in neurotoxicity, and, at high concentrations, ALA inhibits neural Na + /K + -adenosine triphosphatase (ATPase) and leads to the breakdown of membrane anion gradients (115). Although it is reasonable to speculate that ALA may be a major toxin involved in the neurologic dysfunction of the acute porphyrias, the severity of the attack does not correlate well with serum or urine ALA levels (90). Moreover, high serum and urine levels occur in patients without demonstrable neurologic abnormalities (116). The cerebrospinal fluid may also be devoid of ALA during an acute attack, although the significance of this is uncertain because cerebrospinal fluid levels do not correlate with intracellular neural levels (116). Many of the aforementioned effects of ALA occur at concentrations that are unlikely to exist in tissues during acute porphyric attacks. Another potential cause of neurologic dysfunction is impaired heme synthesis. This can produce a decrease in intracellular hemoproteins, leading to depressed cellular respiration in nerve tissue. Impaired hepatic metabolism can also be a consequence of abnormal heme synthesis. A deficiency of hepatic tryptophan pyrrolase, which catalyzes the first step of tryptophan degradation, can result and cause an elevation in the level of 5-hydroxytryptophan (serotonin). Increased excretion of serotonin has been reported in a few patients with acute porphyria (117). Limited heme synthesis in PBG deaminase–deficient mice produces a specific deficiency in the hemoprotein cytochrome P-450 2A5. Necropsy findings vary with the duration of the attack. If the attack is of short duration, no discernible nerve damage is seen. With prolonged duration, axonal damage and, eventually, demyelinization of autonomic, motor, and sensory nerves occurs (92). This correlates with the observation that early therapeutic intervention (i.e., prior to neuronal death) is associated with complete and rapid recovery. Once paralysis is established, recovery depends on axonal regeneration. Recovery of proximal muscle groups occurs earlier than it does in the distal groups, which are innervated with longer axons. PBG deaminase–deficient mice develop a progressive motor neuropathy with normal or minimally elevated ALA levels (106). These data are most consistent with a dysfunction of hemoproteins causing the neuropathy of porphyria (106).

Management of the Attack Because of the unpredictable nature of an acute porphyric attack, it is generally advisable to hospitalize the patient early during an episode. Therapy should follow several steps (Fig. 38.6). First, any porphyrinogenic drug should be discontinued, and drugs that may exacerbate the attack should be avoided (Table 38.4). If the attack is precipitated by an infection, the infection should be treated promptly. An adequate caloric intake should be maintained because diminished oral intake can precipitate or aggravate an attack (118,119). The diet should provide at least 400 g of glucose or another rapidly metabolized carbohydrate daily. A high carbohydrate intake is beneficial because of its suppressive effect on hepatic ALA synthase activity (120). Patients who cannot take carbohydrates by mouth should be given a high carbohydrate feeding through a nasogastric feeding tube and/or intravenously as 10% glucose. Intravenous fluids should be given at a rate more than 2 L/day in the form of normal saline. The patient should P.1096 be monitored for the development of hyponatremia, which may occur because of the inappropriate secretion of antidiuretic hormone. The patient should also be monitored for the progression of neuropathy, with particular attention to changes in respiratory function. Serial measurements of vital capacity and forced expiratory volume should be taken, and ventilatory support should be provided if respiratory depression develops.

▪ Figure 38.5 Schematic showing that neurologic dysfunction in the inducible porphyrias is linked with the biochemical abnormalities. It may be caused by the neurotoxic effect of δ-aminolevulinic acid (ALA), a heme-deficient state, or a combination of both.

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▪ Figure 38.6 Scheme for the management of acute porphyric attack. ALA, δ-aminolevulinic acid; PBG, porphobilinogen.

Although the product labeling recommends an initial trial of intravenous glucose, an expert panel recommends starting hematin therapy early for most acute porphyric attacks (104). Hematin (ferriheme hydroxide) is the chemical form of heme in aqueous solution at physiologic pH. Exogenously administered hematin suppresses hepatic ALA synthase activity (23,121,122,123). Hematin was first administered to a patient with an acute porphyric attack in 1971 (124) and became available as an orphan drug in 1983. It is available in the United States as lyophilized powder for reconstitution into sterile water just before infusion (Panhematin, Ovation Pharmaceuticals, Deerfield, Illinois). In Europe, it is also available as heme arginate (Normosang, Leiras Oy Pharmaceuticals, Helsinki, Finland). Hematin, administered intravenously in a dose of 3 to 4 mg/kg body weight once daily for 4 days, causes a prompt decline in serum and urine levels of ALA and PBG (Fig. 38.7) (125,126). Antipyrine metabolism also improves (127,128,129,130), suggesting that apoproteins of cytochrome P-450 are reconstituted with heme therapy. Despite its impressive pharmacologic effects, the clinical effect of hematin is less predictable. There have, in fact, been no randomized, double-blind studies that show a clinical benefit for hematin during an acute porphyric attack, although many physicians who manage such patients believe that it is of benefit. Hematin should be given before advanced neuronal damage occurs because this is usually not reversed. The most common complication of hematin therapy is thrombophlebitis, which can be prevented by P.1097 administering the solution for 15 to 30 minutes in a free flow through an intravenous line. A transient coagulopathy may be caused by breakdown products of hematin; therefore, it should be given as soon as possible after it has dissolved in an aqueous solution. Dissolving hematin in human serum albumin protects it from degradation (129). Tin protoporphyrin, which inhibits heme oxygenase and thereby prevents the breakdown of heme, has been used in combination with hematin to prolong biochemical remission (131).

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▪ Figure 38.7 Effect of intravenous infusion of heme arginate (3 mg/kg) on the excretion of δaminolevulinic acid (ALA) and porphobilinogen (PBG) in six patients with acute intermittent porphyria (mean ± SE). (From Mustajoki P. Acute intermittent porphyria. Semin Dermatol 1986;5:155, with permission.)

The symptoms and signs of the attack should be treated while glucose and/or hematin is given. Pain, which can be very severe, should be controlled with narcotics, if necessary. Agitation can be controlled with chloral hydrate or chlorpromazine, and ondansetron can be used to relieve nausea and vomiting. Propranolol, in a dosage of 20 to 200 mg/day, can be used for hypertension and tachycardia, although it should be used cautiously (132). Seizure activity is a particularly difficult problem because most of the anticonvulsants (particularly the barbiturates and phenytoin) precipitate acute attacks. Bromides are safe but difficult to use. Clonazepam in low doses that produce levels up to 6 mg/dL may be administered, and new drugs, such as gabapentin, are promising (100). Status epilepticus can be controlled with diazepam (up to 10 mg intravenously), paraldehyde (8 to 10 mL rectally), or magnesium sulfate (0.5 to 1.0 g/hour by intravenous infusion). Many patients have a limited number of porphyric attacks in their lifetime and do well if they avoid porphyrinogenic drugs, fasting, and excessive alcohol intake. However, some patients have recurrent attacks and pose a challenging problem. They are prone to narcotic addition, and pain management becomes a critical feature of their care. Available studies have not clearly shown that the regular administration of hematin is beneficial in this situation (133). For such patients liver transplantation may be considered because this has corrected the biochemical and clinical abnormalities in one patient with AIP (134). In some women, attacks are related to the menstrual cycle, beginning a few days before the onset of menses and ending after it has begun. The attacks are probably caused by endogenous progesterone. Analogs of gonadotrophin-releasing hormone have been used in the management of these cases (135). These agents prevent the normal cyclic secretion of luteinizing hormone and follicle stimulating hormone by the pituitary. Oral hormonal contraceptive use is associated with acute attacks in some patients, but menopausal hormone replacement therapy only rarely affects acute porphyries. Pregnancy is usually well tolerated, but there is an increased frequency of miscarriage.

Prevention of Attacks Individuals who have suffered acute porphyric attacks should wear bracelets stating that they have porphyria. They should also be provided a list of drugs that are safe for use, as well as those that are unsafe. They should be instructed to avoid fasting and excess intake of alcohol and to have infections treated promptly. Treatment with erythropoietin may reduce the severity of porphyric attacks in some patients (136). Measurement of erythrocyte PBG deaminase activity has shown that many individuals related to patients with AIP are latent carriers of the gene defect. They have no clinical manifestations, and many have normal excretion rates for ALA and PBG. Although the natural history of the latent state remains unclear, carriers of the gene defect have the potential to develop acute attacks and should therefore avoid factors that are incriminated in precipitating attacks (e.g., sulfonamides, barbiturates, hydantoins, fasting, and excessive intake of alcohol). Erythrocyte PBG deaminase activity should be measured in first-degree relatives of patients with AIP. Children should be assessed as they approach puberty. As gene testing develops, it should also be utilized for families in which acute porphyria is present. Patients in whom the enzyme abnormality/gene defect is found should be managed along the guidelines outlined for latent individuals.

Hepatocellular Carcinoma in Acute Porphyrias Limited information is available about structural liver changes in the acute porphyrias. Fatty infiltration and siderosis, together with a mild inflammatory process, have been seen in liver biopsy specimens, and crystalline material has been found within mitochondria (134,137). Functional studies have shown there is impaired hepatic mixed-function oxidase activity (137). There is an association between the acute porphyrias and hepatocellular carcinoma (138,139,140). The relative risk of developing hepatocellular carcinoma in acute porphyrias is 30 to 60 times that for the general population (138,141). It has been speculated that carcinogenic substances may accumulate because the hepatic detoxification mechanism is impaired (140).

Porphyria Cutanea Tarda PCT is traced to Günther's description, in 1911, of adult patients who had cutaneous lesions but no neurologic abnormalities (142). The term was first used by Waldenström to distinguish the disorder from the P.1098 porphyrias in which both cutaneous lesions and neurologic dysfunction occur (80). Tarda was included in the name because the disorder occurred late, commonly after the fourth decade of life. However, the familial form of PCT may begin in childhood (143,144). PCT is the most common porphyria with clinical expression in the United States, although its exact prevalence is unknown. It is frequently associated with ethanol use. Among the Bantu of South Africa, a high prevalence is seen; this has been attributed to the ingestion of a local beer brewed in iron pots (145). The disorder was previously identified much more commonly in men, but the proportion of women diagnosed with PCT has

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increased. This reflects, in part, the increasing use of oral contraceptives and estrogen preparations, which also precipitate PCT (146). Although most cases are sporadic, families with PCT have been identified, in which there is autosomal dominant inheritance with variable penetrance (54,57,147). In contrast to the sporadic cases, in which the abnormality in uroporphyrinogen decarboxylase is restricted to the liver, the familial cases also have a deficiency of erythrocyte uroporphyrinogen decarboxylase activity (148). PCT can also be acquired through toxic exposure. In the late 1950s, an epidemic occurred in Turkey after the widespread ingestion of seed grain that had been treated with the fungicide hexachlorobenzene (149). Experimental porphyria mimicking PCT has been induced with a number of structurally related compounds, including polychlorinated and polybrominated biphenyl and dioxin compounds (150).

Disorders Associated with Porphyria Cutanea Tarda Several disorders are associated with the development of PCT. Most notable has been the striking association with chronic hepatitis C (See “Porphyria Cutanea Tarda and Hepatitis C”). Systemic lupus erythematous, rheumatoid arthritis, Sjögren's syndrome, and acquired immunodeficiency syndrome (AIDS) have also been associated with PCT (151,152,153,154,155). Increased porphyrin levels in the dialysate and plasma of patients on long-term hemodialysis have been reported (156,157,158). This may occur irrespective of the development of cutaneous lesions (158).

Porphyria Cutanea Tarda and Hepatitis C There is a significant increase in the prevalence of chronic hepatitis C in patients with PCT compared with the general population (151,152,153,154,155,159,160,161,162,163,164). There is striking geographic variation in this association. The highest prevalence is found in southern European countries, where chronic hepatitis C is found in 60% to 90% of patients with PCT (152,159). A large study in the United States found the prevalence to be 56% in 70 unselected patients with PCT (78). Hepatitis C virus (HCV) infection was documented by a positive test for both hepatitis C antibody and RNA. The patients with PCT who had hepatitis C infection did not differ from those without infection in terms of the type or severity of skin lesions, or in the level and pattern of urinary porphyrin excretion. However, this condition was more frequent in men and among those with a higher rate of alcohol use. The causal relationship between hepatitis C and PCT, if any, remains unclear (165). Only about 1% to 5% of patients with chronic hepatitis C have clinical PCT (159), and conversely many patients with PCT do not have chronic hepatitis C. Viral parameters of hepatitis C such as genotype and viral level do not appear to be important (166). Other possibilities are that hepatitis C alters hepatic iron metabolism or promotes oxidative stress in hepatocytes, which brings out overt PCT in susceptible individuals. Overall, PCT is now considered to be an extrahepatic manifestation of HCV infection.

Porphyria Cutanea Tarda and HFE Mutations Hepatic iron overload is common in patients with overt PCT. Because iron removal returns porphyrin excretion to normal and ameliorates the clinical features in PCT, hepatic iron overload appears to be an important factor in causing the disease. Before the identification of the HFE gene, it was controversial whether patients with PCT may have inherited a gene mutation for hemochromatosis, which caused hepatic iron overload. Subsequently, studies from many countries demonstrated that 40% to 50% of patients with PCT carry the C282Y mutation in the HFE gene, with 10% to 20% being homozygous (77,166,167). A study from the United States showed that 42% of patients with PCT carried the C282Y mutation (15% were homozygous) and another 31% carried the H63D mutation (8% were homozygous). Therefore, there appears to be an increased prevalence of the hemochromatosis gene mutations in patients with PCT (168), suggesting a mechanism by which some patients with PCT have increased hepatic iron levels.

Biochemical Evaluation of Porphyria Cutanea Tarda The diagnosis of PCT is generally made on a clinical basis, but biochemical confirmation, by demonstrating increased urine excretion of uroporphyrin, should be made. Urine heptacarboxyl and hexacarboxyl porphyrin levels are also elevated. Coproporphyrin and P.1099 pentacarboxyl porphyrin levels are elevated to a lesser degree. Urinary PBG is not increased, but a slight elevation in ALA level is common. Fecal porphyrin analysis demonstrates that porphyrins are present in the form of isocoproporphyrins.

Photocutaneous Lesions in Porphyria Cutanea Tarda The presenting clinical manifestation of PCT is nearly always the development of bullous lesions in areas of sun exposure (Fig. 38.8). The lesions occur after minor trauma because of increased skin fragility. The dorsum of the hand is most frequently involved. Other sites include the forehead, neck, and ears. The bullae may become infected, causing delayed healing that produces scarring and pigment changes. Hypertrichosis occurs in the periorbital area, a feature that was prominent in the Turkish epidemic. Milia, which are small white papular lesions, form as a chronic manifestation of the disorder. Sclerodermoid changes may also develop. The skin lesions in PCT are the same as those in variegate porphyria and hereditary coproporphyria. The rare disorder, hepatoerythropoietic porphyria, also features skin lesions similar to those in PCT. In contrast to PCT,

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skin lesions occur in infancy and tend to diminish with age. Porphyrins are produced in excess and accumulate in the skin of patients with the cutaneous porphyrias. In the disorders in which bullous lesions occur, hydrophilic porphyrins accumulate within lysosomes of cells (169). The severe lesions in PCT may be due to the release of proteolytic enzymes from lysosomes into the cytoplasm (Fig. 38.9) (170). Complement activation may also contribute to the pathogenesis of the cutaneous lesions in PCT. Complement compounds are deposited at the dermal–epidermal junction near bullae, and elevated levels of complement components and cleavage products are found in the fluid contained in the lesions (171). Complement levels in serum containing excess porphyrin decline after ultraviolet irradiation (171). Uroporphyrin also stimulates collagen biosynthesis by fibroblasts, which may contribute to the sclerodermoid skin changes in PCT.

Liver Damage in Porphyria Cutanea Tarda Patients with clinically overt PCT usually have liver damage. Approximately two thirds of patients have an elevation in the serum transaminase level at the time of diagnosis (172,173,174,175). The liver may have a patchy gray discoloration when viewed grossly (172). Liver biopsy specimens exhibit red fluorescence when exposed to P.1100 ultraviolet light (176). If a water-free preparation of tissue is used, a cytoplasmic distribution of fluorescence is observed. Needle-like cytoplasmic inclusions are found in specimens from untreated patients (Fig. 38.10) (177). The inclusions, which appear to be uroporphyrin crystals, are water soluble and are lost during tissue processing unless water-free fixation is used.

▪ Figure 38.8 Skin lesions in porphyria cutanea tarda. Erosions and bullae (arrows) occur in sun-exposed areas after minor trauma. Milia (arrowhead) are small, whitish papules found on the dorsal aspects of the hands. There is increased facial hair in the periorbital region. Similar skin changes are found in variegate porphyria, hereditary coproporphyria, and hepatoerythropoietic porphyria. (From Bloomer JR. The hepatic porphyrias. Gastroenterology 1976;71:689, with permission.)

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▪ Figure 38.9 Sequence by which damage to skin and other tissues may be produced when porphyrins are exposed to light in the presence of molecular oxygen. Uroporphyrin preferentially causes injury to lysosomes in cells, whereas cell membranes and mitochondria appear to be the principal targets in protoporphyrin-induced damage.

Patients with PCT commonly have some degree of hepatic iron overload, and hemosiderosis is usually demonstrated with iron stains (134,172,174,175). The accumulation of iron occurs not only in patients who abuse ethanol but also in familial and estrogen-induced PCT (134,174). The iron is distributed diffusely but is most frequent in Kupffer cells and clusters of macrophages. Fatty infiltration of the liver is also common, having been reported in most biopsy specimens. Although this may be related in part to underlying ethanol abuse, one study found no difference in the prevalence of fatty liver in alcoholic versus nonalcoholic patients with PCT (174). The fatty changes are usually mild. Granuloma-like clusters of mononuclear cells, Kupffer cells, hemosiderin, and ceroid have been described as lobular lesions of PCT (175). They occur with variable frequency and may represent a reaction to collections of iron and uroporphyrin. Hepatitis C may contribute to the liver damage in PCT. Liver biopsy specimens from patients with PCT who are positive for hepatitis C antibody have changes similar to those from patients with hepatitis C alone, including lymphoid follicles, bile duct damage, and hepatocellular necrosis (153). The extent of hepatic damage is variable, ranging from minimal injury to cirrhosis, and appears to be related, in part, to the duration of PCT (175). No definite relationship has been established between ethanol abuse and progression of liver damage, and alcoholic hepatitis is infrequent in PCT (172,174). Although hepatic iron overload may contribute to liver damage, the correlation between the degree of siderosis and the severity of liver damage is poor. Nevertheless, phlebotomy produces improvement in some, but not all, of the abnormalities. Hemosiderosis disappears as total iron stores are depleted. Fluorescence and the crystalline material, as well as the granuloma-like lesions, disappear. The liver enzyme abnormalities return toward normal. Improvement usually occurs irrespective of continuation of the use of ethanol (173).

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▪ Figure 38.10 Hepatic crystals in porphyria cutanea tarda and protoporphyria. A: Light micrograph shows intracytoplasmic crystals (arrow) in a hepatocyte of a patient with porphyria cutanea tarda (hematoxylin and eosin stain). B: Transmission electron micrograph shows a cluster of crystals (surrounded by arrows) in a hepatocyte of a patient with protoporphyria. A scanning electron micrograph shown in the inset also demonstrates the crystalline material (surrounded by arrows). (From Rank JM, Straka JG, Bloomer JR. Liver in disorders of porphyrin metabolism. J Gastroenterol Hepatol 1990;5:573, with permission.)

P.1101 PCT has been associated with hepatocellular carcinoma. The first report of this relationship was in 1957, when apparent PCT was noted in a patient with a hepatic tumor that fluoresced when exposed to ultraviolet light (178). After surgical removal of the tumor, the patient's skin lesions improved and porphyrin excretion returned to normal. There have been other reports of porphyrin-excreting tumors in which the biochemical abnormalities were somewhat different from those usually seen in PCT, with increased excretion of several porphyrin compounds in addition to uroporphyrin (179). The more common association is the development of hepatocellular carcinoma in patients with long-standing PCT. The frequencies of cirrhosis and hepatocellular carcinoma were 63% and 53%, respectively, in a 1979 autopsy series (180). The diagnosis of PCT had been made several years before death in all cases. A 1972 autopsy series of patients with PCT in Czechoslovakia found cirrhosis in 64% and carcinoma in 47% (181). The severity of liver disease and the development of carcinoma correlated with the length of time after the diagnosis of PCT was made. The duration was 3.7 years for patients without cirrhosis, 6.3 years for those with cirrhosis but no carcinoma, and 11.7 years for those with carcinoma. Cirrhosis was present in all cases with hepatocellular carcinoma. Ethanol use was not universal, and the degree of hepatic hemosiderosis was variable. In two other studies, conducted in 1982 and 1985, an increased incidence of hepatocellular carcinoma was also found (182,183). The presence of carcinoma correlated with male sex, duration of time after the diagnosis of PCT, and cirrhosis. There was no correlation with ethanol use or hepatitis B serology. However, none of 96 Italian patients screened with radionuclide liver scan and measurement of serum α-fetoprotein had evidence of tumor (184). Because these studies were carried out before the discovery of the HCV, the role of chronic hepatitis C in the development of hepatocellular carcinoma could not be determined. A recent study from the Netherlands found the incidence of hepatocellular carcinoma to be 13% in the 38 patients with PCT who were followed up for 2 to 18 years (161). There was no difference in the prevalence of hepatitis C infection in patients with hepatocellular carcinoma (20%) compared to those P.1102 without (18%). Therefore, hepatocellular carcinoma may develop in patients with PCT irrespective of the presence of hepatitis C infection. These studies suggest that there is an increased risk for developing cirrhosis and hepatocellular carcinoma for patients with long-standing PCT. Additional studies are needed to clarify the role of hepatitis C in this process. In any event, it is probably prudent to screen patients with long-standing PCT, particularly those with chronic hepatitis C and/or cirrhosis, for hepatocellular carcinoma by measuring serum α-fetoprotein and by hepatic ultrasonography.

Management in Porphyria Cutanea Tarda

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The patient with active PCT should avoid wavelengths of light that may excite porphyrins. This occurs maximally at a wavelength of 400 to 410 nm. Light of this wavelength is not filtered by window glass; therefore, the patient should take precautions when driving a car. Fluorescent lights should also be avoided. Patients should stop ingesting ethanol, and women taking birth control pills should use another form of contraception. Patients should also not take iron-containing compounds. Despite discontinuing the precipitating factors, improvement will be slow unless other therapy is used (Fig. 38.11). The mainstay of therapy is phlebotomy (185,186), which is based on the observation that hepatic siderosis is common and that iron probably plays an important role in the pathogenesis of the disease. The liver typically contains an excess of 2 to 4 g iron, and the amount of phlebotomy needed will be on the order of 4 to 8 L of blood. After phlebotomy is completed, urine levels of uroporphyrin will continue to decrease toward normal, and more than 90% of patients will have normal levels after 6 to 12 months. Resolution of skin fragility will accompany the decrease in uroporphyrin excretion, and patients will no longer develop vesicles or erosions. Hirsutism and hyperpigmentation may take months to clear after phlebotomy is completed, and sclerodermoid changes may not resolve for several years. Iron-containing compounds should not be ingested because this may cause a relapse. For patients who do not tolerate phlebotomy or who continue to have cutaneous symptoms despite an adequate course of phlebotomy, chloroquine or related compounds can be administered (186). These compounds appear to form complexes with uroporphyrin and heptacarboxyl porphyrin, enhancing their removal from tissues and excretion in urine. The initial dose should be 100 mg of hydroxychloroquine or 125 mg of chloroquine three times a week. Larger doses may cause hepatic injury related to the massive removal of uroporphyrin from the liver. In an uncontrolled clinical trial, high-dose vitamin E reduced urine uroporphyrin levels in five patients with PCT (187). It is unclear how the patient with PCT and concomitant chronic hepatitis C should be managed. A few reports suggest that interferon therapy may reduce P.1103 the manifestations of PCT. However, until this has been studied more carefully, it is probably best to institute a course of phlebotomy before starting antiviral treatment.

▪ Figure 38.11 Scheme for management of the patient with active porphyria cutanea tarda (PCT). ALT, alanine aminotransferase; TIBC, total iron-binding capacity; tiw, three times a week.

For the patient with chronic renal failure who develops cutaneous lesions of PCT while on hemodialysis, standard phlebotomy is usually contraindicated because of anemia. In this situation, erythropoietin therapy accompanied by small-volume phlebotomies has been used successfully (188).

Erythropoietic Protoporphyria In 1961, Magnus et al. (189) described a 35-year-old man who had lifelong itching and edema of his skin on exposure to sunlight. His urinary excretion of porphyrins and porphyrin precursors was normal, but his red cells and feces contained excess protoporphyrin; therefore, they proposed the name erythropoietic protoporphyria (EPP) for his condition. Erythrohepatic protoporphyria and protoporphyria have also been used as names for the disorder. EPP occurs in all ethnic groups, but the precise prevalence has not been determined for any group. The pattern of inheritance was previously considered to be that of an autosomal dominant disorder with variable expression. Some individuals who carry a mutant ferrochelatase gene in one allele have no clinical manifestations of the disease, and their porphyrin levels may be normal. Most patients with symptomatic protoporphyria have ferrochelatase activity that is significantly less than the expected 50% of normal in a classic autosomal dominant disease (190). These results are explained in part by the inheritance of a mutation in one ferrochelatase allele that structurally alters the protein together with a low-expressing nonmutant ferrochelatase allele caused by a polymorphism in an intron (IVS 3–48 T/C) (191,192). There is no difference between sexes in

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the frequency of the disorder, either for the gene defect or for the clinically expressed disease.

Biochemical Evaluation of Erythropoietic Protoporphyria The biochemical hallmark of EPP is an increased level of protoporphyrin in red cells and feces. The excess protoporphyrin does not form complexes with a metal, unlike iron deficiency and lead poisoning, in which excess red cell protoporphyrin is chelated to zinc (193). The diagnosis is established by demonstrating an elevated red cell protoporphyrin level in a patient who has the typical clinical features. Patients with EPP do not excrete increased amounts of PBG and ALA in urine. This implies that hepatic ALA synthase activity is not increased, although in vitro measurements have shown otherwise in some instances (194). In most patients normal amounts of heme are synthesized in liver tissue and bone marrow, but in approximately 25% there is mild anemia characterized by microcytic indices (195). Iron metabolism is normal (196), and iron deficiency can exacerbate the accumulation of protoporphyrin in red cells (197). Once the red cell enters the circulation, protoporphyrin is released into the plasma within a few days (unless liver disease is present) and is then excreted by the liver into bile (Fig. 38.12) (See “Excretion of Porphyrins and Porphyrin Precursors”) (198). Bone marrow is the major source of excess protoporphyrin in most patients. Studies using radiolabeled precursors of protoporphyrin have indicated that the liver also contributes to excess protoporphyrin production (199,200), although the interpretation of these studies has been controversial (201). Metabolic balance studies comparing fecal protoporphyrin excretion with the total mass of red cell protoporphyrin have occasionally demonstrated a significant discrepancy, also indicating a hepatic contribution (202).

Photosensitivity in Erythropoietic Protoporphyria The principal clinical manifestation in EPP is photosensitivity. This is usually lifelong, often beginning in infancy. Rarely, the photosensitivity has onset in adulthood (203). Patients experience burning or stinging of the skin on exposure to sunlight. Window glass does not prevent the reaction because the wavelength of light that causes the photosensitivity (400 to 410 nm) is not filtered by window glass. For some patients, photosensitivity is caused by light emitted from fluorescent fixtures. Erythema and edema of the skin develops and may persist for several days (Fig. 38.13). Unlike PCT, the development of vesicles and erosions is rare. Chronic skin changes are characterized by thickening and lichenification of the skin over the nose and the dorsum of the hand, as well as shallow scars (Fig. 38.13. Microscopic examination of the skin demonstrates the deposition of periodic acid schiff (PAS)-positive material around the walls of capillaries in the dermis (204). Photosensitivity is caused by excess protoporphyrin circulating in blood or deposited in skin tissue, or a combination of the two. Absorption of light energy by the porphyrin molecule raises the molecule to an excited state in which it reacts with molecular oxygen to produce reactive oxygen species (Fig. 38.9). Cell membranes and mitochondria appear to be the principal targets for protoporphyrin-induced damage (169). The damage is attributed to cross-linking of membrane proteins and peroxidation of membrane lipids (205,206). P.1104 P.1105 The activation of complement may also be a factor because complement is depleted in serum containing protoporphyrin when the serum is exposed to light (207). Mast cells release serotonin and arachidonic acid when incubated with protoporphyrin and exposed to ultraviolet light; this may contribute to the photosensitivity as well (208).

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▪ Figure 38.12 Protoporphyrin metabolism in protoporphyria. As a consequence of deficient ferrochelatase activity, protoporphyrin accumulates in heme-forming tissues—primarily the bone marrow, with a variable contribution from the liver. This excess protoporphyrin undergoes biliary excretion. Enterohepatic circulation of protoporphyrin contributes to the amount that the liver must excrete in bile. (From Bloomer JR. The liver in protoporphyria. Hepatology 1988;8:407, with permission.)

▪ Figure 38.13 Cutaneous lesions in protoporphyria. A: Acute photosensitivity reaction showing edema of the face and erythema on the bridge of the nose following sun exposure. B: Chronic skin changes on the hand of a patient with protoporphyric liver disease. There is thickening and lichenification of the dorsum of the hand in areas where there was repeated sun exposure.

Hepatobiliary Disease in Erythropoietic Protoporphyria In 1963, a 6-year-old boy who had the biochemical features of EPP along with hepatosplenomegaly and abnormal liver chemistries was described. At the time of subsequent splenectomy, he was found to have a cirrhotic liver (209). In 1968, it was reported that patients with EPP may develop a liver disease that progresses to liver failure (210). The frequency remains uncertain, although less than 10% of patients appear to develop this complication. Severe liver disease has occurred in both men and women, and in children and adults. A synergistic effect with alcohol has been reported (211), but liver disease usually develops in the absence of other causes of liver injury. Laboratory study results are nonspecific, showing variable hyperbilirubinemia with mild to moderate increases in serum transaminase and alkaline phosphatase levels. Red cell protoporphyrin levels are significantly higher than those in the usual patient with EPP, ranging from 1,404 to 36,800 µg/dL (211). Along with signs and symptoms of hepatic decompensation, patients have neurologic symptoms that include severe abdominal pain that often radiates into the back (212). Prognosis is poor once jaundice develops in a patient with liver disease due to EPP. The livers of patients who die of hepatic failure or undergo liver transplantation are black in color (Fig. 38.14) because of massive deposits of protoporphyrin pigment in hepatocytes, macrophages, Kupffer cells, and biliary structures. The pigment deposits are birefringent when examined by polarization microscopy (213,214) because of the fact that they contain crystals (Fig. 38.10) (215). The liver damage appears to be caused by the progressive accumulation of protoporphyrin in the liver. Regardless of the source of the excess protoporphyrin, the only means for its excretion is by hepatic clearance and secretion into bile (4). During this process, protoporphyrin is kept in solution through protein binding because it is a poorly water-soluble compound that aggregates in aqueous solution. Protoporphyrin may aggregate and form crystalline deposits within hepatocytes and small biliary radicals when concentrations are high. These deposits obstruct bile flow and damage hepatocytes. Experimental studies have demonstrated that protoporphyrin is also toxic to the liver when in solution. Perfusion of the isolated rat liver with protoporphyrin causes a reduction in bile flow (216). Histologic examination of the perfused liver shows canalicular dilatation and distortion, and membrane ATPase activity is reduced (217). Membrane dysfunction presumably occurs when the lipophilic protoporphyrin molecule intercalates into the membrane and alters the physical and chemical properties of the membrane (218,219). Studies with a mouse model of EPP also indicate that there may be formation of cytotoxic bile containing high concentrations of bile salts and protoporphyrin that cause biliary

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fibrosis by damaging bile duct epithelium (220).

▪ Figure 38.14 Liver disease in protoporphyria. Resected liver of a patient who underwent liver transplantation shows the liver to be black and fibrotic (top left). Light microscopy demonstrates diffuse pigment deposits in liver cells and the biliary radicles (top right). Fluorescence microscopy demonstrates hepatocytes to be fluorescent because of the presence of protoporphyrin, and polarization microscopy demonstrates birefringence (note the Maltese cross formation) because of protoporphyrin crystals (bottom figures).

Because protoporphyrin accumulation in the liver appears to be responsible for liver damage in EPP, patients with this complication presumably should have a greater abnormality in protoporphyrin metabolism than the usual patient. Indeed, red cell and plasma protoporphyrin levels are significantly higher in patients with liver disease than in the usual patient, and the distribution of protoporphyrin in red cells changes (221,222). The ratio of fecal protoporphyrin excretion to the total red cell protoporphyrin content decreases (221), and the ratio of the concentration of protoporphyrin to that of bile salts in bile increases (215). Although the frequency of severe liver disease is not high in patients with EPP, histologic abnormalities are often found in liver biopsy specimens (223,224). These consist of focal deposits of protoporphyrin pigment, portal fibrosis, and inflammation. Changes in bile canalicular ultrastructure occur early in P.1106 the course of hepatic involvement (225). Patients also appear to have an increased frequency of gallstones, which contain protoporphyrin.

Management in Erythropoietic Protoporphyria Most patients with EPP will require therapy only for photosensitivity. Sunscreens that protect against the wavelength of light (400 to 410 nm) that activates protoporphyrin should be used. Films can be installed on windows to provide protection against light of this wavelength. The oral administration of β-carotene in a daily dosage of 60 to 180 mg reduces photosensitivity in many patients. For the patient in whom liver disease has developed, therapeutic approaches can be tried to diminish the production of protoporphyrin or facilitate its excretion. The oral administration of chenodeoxycholic acid has reduced protoporphyrin levels in some patients (226), as has the correction of iron deficiency (197). However, iron therapy must be used cautiously because in some patients, protoporphyrin metabolism worsens (227). Red cell transfusions and the administration of hematin have also been successful in diminishing protoporphyrin levels (222,228,229). Oral administration of cholestyramine and activated charcoal has been used to interrupt the enterohepatic circulation of protoporphyrin (230,231). A randomized placebo-controlled trial demonstrated that cysteine (500 mg orally twice a day) increased the time of symptom-free light exposure (232). Each of these approaches has a rational basis and does not pose a major risk to the patient. For the patient with early liver damage, administration of cholestyramine should be tried and liver chemistries and red cell protoporphyrin levels should be monitored during therapy. If liver disease is advanced when the diagnosis is established, medical therapy cannot effectively reverse the situation. These patients often have a crisis, showing some of the features that occur during acute porphyria attacks. Their symptoms include severe abdominal pain that may radiate into the back, as well as mild hypertension, tachycardia, and weakness (212). Limited studies indicate that the condition can be stabilized by

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a combination of plasmapheresis and hematin administration, which will allow the patient to be maintained until liver transplantation is carried out (229).

Liver Transplantation in Erythropoietic Protoporphyria Liver transplantation has become the main option for patients with EPP in whom liver disease is advanced, and there have been several reports of success (233,234,235,236,237,238). During transplantation, patients are susceptible to unique problems because of their high protoporphyrin levels. They are at risk for photodamage to skin and abdominal tissue during exposure to fluorescent lights used in operating rooms (236,237,238); therefore, filters should be placed over the lights (238,239). Their tissues should also be protected from light as much as possible during the operation. Paralysis has occurred during the perioperative period from a severe axonal polyneuropathy, which is probably due to the neurotoxic effect of protoporphyrin (236,237,238,240). Exchange transfusion should not be carried out before transplantation because transfused red cells are sensitive to photohemolysis caused by the circulating protoporphyrin (241). However, plasmapheresis should be considered. Unfortunately, liver transplantation does not correct the ferrochelatase defect in the bone marrow, and erythrocyte protoporphyrin levels remain high. Grafts are therefore susceptible to the toxic effects of protoporphyrin (238,242,243). The percentage of patients who developed significant damage in the new liver was 65% in a series of North American patients that was recently reported (244).

Rare Types of Porphyria δ-Aminolevulinic Acid Dehydrase Deficiency Porphyria Porphyria due to ALA dehydrase deficiency has been described in a few individuals (245,246). This autosomal recessive disorder results from the homozygous deficiency of the second enzyme in the heme biosynthetic pathway. Enzyme activity in affected patients is less than 3% of normal, and in obligate heterozygotes, 50% of normal. As predicted from the enzyme defect, patients excrete markedly elevated amounts of ALA in the urine. Of interest, urinary coproporphyrin and erythrocyte protoporphyrin levels are also increased, the mechanisms of which are not understood. Children with this disorder have severe recurring porphyric attacks that respond poorly to medical therapy, including the use of intravenous glucose and hematin. As outlined in the management of the more common types of acute porphyria, patients with this disorder should avoid medications that may precipitate neurologic crises. There has been one report of successful liver transplantation, which resulted in resolution of the symptoms (247).

Congenital Erythropoietic Porphyria Despite its rarity, congenital erythropoietic porphyria was the first type of porphyria to be described in the medical literature. In 1874, Schultz (86) reported P.1107 a patient who had dark urine and fragile skin since infancy. Fewer than 200 cases have subsequently been described. It is an autosomal recessive disorder that is usually diagnosed in infancy (248); only a few cases of adult onset have been reported (249,250). Skin lesions are indistinguishable from those in PCT. The teeth develop a reddish brown color and fluoresce when examined with ultraviolet light because of porphyrin deposition in the dentin. The bone marrow is filled with red cell precursors that fluoresce with ultraviolet irradiation. Unlike PCT, the liver shows little or no fluorescence. The disorder is associated with chronic hemolysis, and splenomegaly is common (251,252). The cause of hemolysis is not well understood but may be related to the toxic effect of porphyrin on the erythroid cells. Neurologic symptoms do not occur. Treatment is difficult. Therapy is usually directed at hemolysis in an attempt to decrease heme turnover. Splenectomy is associated with a variable response, ranging from no effect to long-term remission of disease (253). Red cell transfusions decrease porphyrin excretion and ameliorate clinical symptoms but may cause iron overload (252). Intravenous administration of hematin has also been shown to decrease uroporphyrin excretion (250,252), but this has not been used as long-term therapy.

Hepatoerythropoietic Porphyria Hepatoerythropoietic porphyria was first described by Gunther in 1967 and received its name in 1975 (244,254). It manifests early in infancy with discolored urine, photosensitivity, and skin fragility. Hemolytic anemia and splenomegaly may be present. As the patient reaches adulthood, the skin manifestations may diminish (255). As the name implies, significant amounts of porphyrins are produced in both the liver and bone marrow, and normoblasts in bone marrow aspirates fluoresce. Markedly elevated levels of uroporphyrin are present in the urine. Erythrocyte protoporphyrin levels are also increased, mainly as the zinc chelate. The disorder is caused by a marked deficiency of uroporphyrinogen decarboxylase activity in heme-forming tissues (256,257,258,259). Studies of relatives of patients demonstrate mutations in both alleles of the gene coding for uroporphyrinogen decarboxylase enzyme (259,260). This contrasts with familial PCT, which is associated with heterozygous deficiency of uroporphyrinogen decarboxylase activity (257,261). Although a deficiency of uroporphyrinogen decarboxylase activity explains the increased excretion of uroporphyrin, the cause of elevated zinc protoporphyrin levels is unexplained. A nonspecific hepatitis has been reported, and mild increases in serum transaminase levels are common. In

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contrast to PCT, hepatic siderosis has not been reported and serum iron study results are normal. Fibrosis/cirrhosis is also uncommon. There is little information available about therapy. Treatment is designed primarily to protect the skin from sunlight.

Dual Porphyrias and Harderoporphyria Occasionally families have been described in which individuals have a deficiency of more than one enzyme of the heme biosynthetic pathway. This includes patients who have coexistent variegate porphyria and PCT (262) and those in whom deficiencies of PBG deaminase and uroporphyrinogen decarboxylase activity cause symptoms of AIP, PCT, or both (263). These conditions are called dual porphyria. A French family has been described in which coproporphyrinogen oxidase activity is approximately 10% of normal in three homozygous individuals and 50% of normal in heterozygotes. Instead of increased urinary excretion of coproporphyrin, which would be expected as a result of the enzyme deficiency, the affected individuals excreted 3-carboxyl porphyrin (harderoporphyrin) in excess amounts (264). Kinetic studies indicated that the defect in the mutant enzyme caused 3-carboxyl porphyrinogen to dissociate from the enzyme more readily than normal. Harderoporphyria has also been reported in a German family (265).

Secondary Porphyrinuria Several nonporphyric disorders are associated with an increase in the urinary excretion of porphyrins, particularly coproporphyrin, in a condition termed secondary P.1108 porphyrinuria (Table 38.5). Patients with these disorders may also have abdominal pain and other symptoms of acute porphyria, which can present a diagnostic dilemma. If this situation is encountered, it is important to remember that patients who are symptomatic with acute porphyric attacks have increased urinary excretion of ALA and PBG. With the exception of lead poisoning and hereditary tyrosinemia, urinary excretion of these compounds is normal in all the conditions associated with secondary porphyrinuria. The amount of urinary ALA and PBG excretion should therefore be determined to distinguish between acute porphyria and secondary porphyrinuria.

Table 38.5. Causes of Secondary Porphyrinuria

Hepatobiliary

Acute and chronic hepatitis

disorders

Alcoholic liver disease Cirrhosis (alcoholic and nonalcoholic) Cholestatic disorders

Toxins

Heavy metal poisoning (e.g., lead, arsenic, gold, iron) Benzene and benzene congeners Haloalkanes and haloaromatic compounds

Hematologic disorders

Aplastic, hemolytic, and pernicious anemias Leukemias Hodgkin's disease

Miscellaneous

Diabetes Hereditary conjugated bilirubin disorders (Dubin-Johnson and Rotor's syndromes) Bronze baby syndrome

Lead Poisoning Lead poisoning is associated with several abnormalities in porphyrin metabolism because lead inhibits more than one enzyme (i.e., ALA dehydrase, coproporphyrinogen oxidase, and ferrochelatase) in the heme biosynthetic pathway. Erythrocyte levels of zinc protoporphyrin are elevated in patients with lead poisoning (193); this measurement has been used to screen for the disorder. Lead poisoning is also associated with increased urinary excretion of ALA and coproporphyrin. Because abdominal pain is a prominent clinical feature, and patients may also have peripheral neuropathies, it is possible that the mechanism for neurologic dysfunction in lead poisoning is the same as that in the acute porphyrias. Indeed, hematin has been used as adjunctive therapy in lead poisoning and causes a significant diminution in urinary ALA excretion (266).

Hereditary Tyrosinemia Hereditary tyrosinemia type I is a metabolic disorder characterized by liver damage that develops during infancy and may progress rapidly to cirrhosis, with the subsequent development of hepatocellular carcinoma. Patients with this disorder accumulate succinylacetone (4,6-dioxoheptanoic acid) and succinylacetoacetate because of a

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block in tyrosine metabolism at the level of the fumarylacetoacetase reaction (112). Succinylacetone is a potent inhibitor of ALA dehydrase (267,268) and therefore results in increased urinary excretion of ALA. Some patients also have neurologic manifestations resembling those of the acute porphyrias (269). The mechanism of neurologic dysfunction may be the same because patients with tyrosinemia respond to the intravenous administration of hematin (270). The biochemical abnormalities are corrected by liver transplantation, although minor defects, which are thought to be of renal origin, persist (271).

Miscellaneous Hepatobiliary Diseases Because bile is a route of porphyrin excretion, any hepatobiliary disease in which bile formation is impaired may cause a diversion of porphyrins to the urine (272,273). Therefore, urinary excretion of coproporphyrin increases the most in hepatobiliary diseases. Uroporphyrin levels may also increase, but protoporphyrin is not excreted in urine, even in the face of severe cholestasis, because of its poor water solubility. When there is biliary obstruction, urinary coproporphyrin, whose excretion is increased, contains a higher proportion of the type I isomer than usual (274). Two patterns of excretion have been observed in parenchymal liver diseases. In alcoholic cirrhosis, the increased excretion of urine coproporphyrin is associated with a proportion of coproporphyrin I in urine similar to that seen in normal individuals, whereas the pattern in other types of parenchymal disease is more like that seen in biliary obstruction. However, because of a significant overlap among these conditions, the coproporphyrin isomer distribution in urine cannot be used in the differential diagnosis of hepatobiliary disorders. Acute ingestion of alcohol may also cause a significant increase in urinary excretion of coproporphyrin, usually beginning 2 to 4 days after intoxication. Although impaired biliary excretion is probably the main factor responsible for increased urinary porphyrin excretion in hepatobiliary disorders, there may also be an alteration in heme synthesis. Hepatic ALA synthase activity is increased in homogenates of cirrhotic livers (275), which suggests that there may be an increased rate of porphyrin production. Experimentally, it has been shown that acute ethanol administration also increases hepatic ALA synthase activity (276).

Pseudoporphyria Pseudoporphyria is an entity with clinical and histologic features similar to those of PCT but with normal or near normal porphyrin levels (277,278,279). Pseudoporphyria is characterized by vesicles, bullae, skin fragility, milia, and scarring on the sun-exposed skin. Like PCT, the dorsal surface of the hands are most commonly affected. The histologic and immunofluorescent characteristics of pseudoporphyria are similar to those of PCT. Histologically, there are subepidermal bullae. Direct immunofluorescence reveals granular deposits of immunoglobulin G (IgG) and C3, most commonly at the dermoepidermal junction. Pseudoporphyria has been described in patients with chronic renal failure with or without dialysis, with certain medications, and with ultraviolet A radiation. The medications include nonsteroidal anti-inflammatory drugs P.1109 (highest reported incidence with naproxen), antibiotics including tetracycline, multiple sulfur-bearing diuretics, and isotretinoin (280). Ultraviolet exposure includes ultraviolet A tanning beds, psoralens plus ultraviolet A therapy, and excessive sun exposure. The exact pathogenesis is unknown but may involve photosensitivity and oxidation stress. Treatment involves discontinuation of suspected agents and sun protection. Two children with hemodialysis-associated pseudoporphyria were successfully treated with the antioxidant N-acetylcysteine (277).

Annotated References Anderson KE, Bloomer JR, Bonkovsky HL, et al. Recommendations for the diagnosis and treatment of the acute porphyrias. Ann Int Med 2005;142:439–450. This paper, authored by a group of experts in the field, provides current recommendations for the diagnosis and management of the four types of porphyria in which attacks of neurovisceral symptoms occur. Grandchamp B, Puy H, Lamoril J, et al. Review: molecular pathogenesis of hepatic acute porphyrias. J Gastroenterol Hepatol 1996;11:1046–1052. This review describes the different gene mutations that have been found in acute porphyrias. Lefkowitch JH, Grossman ME. Hepatic pathology in porphyria cutanea tarda. Liver 1983;3:19–29. The pathologic changes in the liver in porphyria cutanea tarda are reviewed, pointing out the distinctions between those changes that appear to be specific to the porphyrias and those that may be related to ethanol abuse or iron overload. McGuire BM, Bonkovsky HL, Carithers RL, et al. Liver transplantation for erythropoietic protoporphyria liver disease. Liver Transpl 2005;11:1590–1596. This paper reports the outcome of liver transplantation in 20 North American patients with erythropoietic protoporphyria liver disease, particularly noting survival rates, unique complications, and recurrence rate of liver disease in the graft. Mustajoki P, Tenhunen R, Pierach C, et al. Heme in the treatment of porphyrias and hematological disorders.

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Semin Hematol 1989;26:1–9. This paper summarizes the effects of heme administration to patients with porphyria and hematologic disorders, such as myelodysplastic syndromes and sideroblastic anemias. There is an excellent bibliography that includes all the clinical trials with heme administration. Poh-Fitzpatrick MB. Pathogenesis and treatment of photocutaneous manifestations of the porphyrias. Semin Liver Dis 1982;2:164–176. The review discusses the pathophysiology of cutaneous manifestations in porphyrias and their treatment. Schmid R, ed. The porphyrias. Semin Liver Dis 1998;18:1–101. Several experts provide a summary of the clinical and biochemical abnormalities that are seen in the different types of porphyria.

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Editors: Title:



Copyright ©2007 Lippincott Williams & Wilkins > Table of Conte nts > Vo lu me 2 > Se ction V II - Gen etics and Metabolic Dise ase > Chapter 39 - Nonalcoho lic Fatty Liver Dise ase

Chapter 39 Nonalcoholic Fatty Liver Disease Stephen H. Caldwell Abdullah M.S. Al-Osaimi Curtis K. Argo

Key Concepts z

Nonalcoholic fatty liver disease (NAFLD) is emerging as the most common liver disorder in industrialized countries and in many developing countries. It exists as a histologic spectrum, ranging from simple steatosis or steatosis with only mild inflammation (types 1 and 2 NAFLD) to more severe steatohepatitis (types 3 and 4 NAFLD or nonalcoholic steatohepatitis [NASH]). Types 1 and 2 NAFLD infrequently progress to cirrhosis but types 3 and 4 NAFLD (i.e., NASH) progress to cirrhosis in as many as 15% to 20% of patients. Progression is often silent, and paradoxically, it is often associated with normalization of the aminotransferases. In histologically advanced cases, the characteristic microscopic findings are lost and patients often present with “cryptogenic cirrhosis.” In addition to the usual complications of cirrhosis and portal hypertension, hepatocellular carcinoma is now recognized as a late complication of NAFLD.

z

Although NAFLD can occur in relatively lean individuals, obesity and type 2 diabetes remain the best characterized risk factors and are predictive (along with older age and hypertriglyceridemia) of the severity of underlying liver histology. Many lean patients with fatty liver actually have increased mesenteric fat deposits (central obesity), and ethnic variation exists in the relationship between body mass index (BMI) and visceral adiposity. In a past series of obese patients, liver biopsy results were normal in only 10%. Approximately 5% of patients have occult cirrhosis and 85% will have steatosis. In the latter, one third have NASH. The prevalence of liver disease among patients with type 2 diabetes and/or hyperlipidemia has not been as well characterized but is thought to be high. Underlying liver disease in these patients has potentially serious implications for treatment of obesity, diabetes, hypertension, and hyperlipidemia—all features of the metabolic syndrome.

z

Although insulin resistance is neither absolutely essential nor sufficient for the development of steatohepatitis, the association is so strong that NAFLD, and more importantly NASH, can be considered a part of the metabolic syndrome and systemic lipotoxicity. As such, it is not surprising that lipid peroxidation is now recognized as the underlying mechanism of hepatocyte injury leading to cytokine activation and fibrosis. Steatosis results from excessive delivery of fatty acids to the liver as a result of peripheral insulin resistance, but de novo hepatic synthesis of triglycerides and impaired export of fatty acids (apolipoprotein metabolism) also contribute to the condition. Variation in the antioxidant influences the risk of subsequent cellular injury. P.1118

z

Exercise and dietary alterations are cornerstones of therapy and may result in histologic improvement. Simple steatosis probably does not warrant pharmacologic therapy but the presence of fibrosis needs a more aggressive approach. Weight loss supplements and weight-reduction surgery may be successful in some but carry a risk of complications. Other potential therapeutic modalities include the use of antioxidants and cytoprotective agents, insulin sensitizers (e.g., biguanides and thiazolidinediones [TZD]), and possibly antihyperlipidemic agents (e.g., fibric acid derivatives and 3-hydroxy-3-methylglutaryl coenzyme A [HMG-CoA] reductase inhibitors), although the latter have been inadequately studied. Confounding variables (e.g., exercise and diet) and sampling error on liver biopsy samples limit interpretation of existing literature. These limitations have led to the need for incorporation of other endpoints in controlled treatment trials including anthropometric indices, measures of physical conditioning, hepatic fat content, indices of lipid peroxidation, measures of insulin signaling, and possibly systemic measures of hepatic fibrosis.

Nonalcoholic fatty liver disease (NAFLD), is an umbrella term that includes a range of conditions ranging from simple steatosis to nonalcoholic steatohepatitis (NASH) (1,2). As apparent from the volume of literature published in just the last 3 years (well over 1,000 articles), it is increasingly recognized as a potentially serious condition, which can progress to cirrhosis, liver failure, and hepatocellular cancer (HCC) and has a worldwide distribution (3,4,5,6,7,8,9). The spectrum of clinical severity, in part, reflects the normal role that the liver plays in fat metabolism— a fat storage site where lipid peroxidation can lead to injury and activation of profibrotic cytokines in some individuals. The explanation for why some people develop steatosis and others do not and why some with steatosis develop injury is related to variable expression of obesity, type 2 diabetes, and the metabolic syndrome—conditions that represent a complex mixture of genetic predisposition and environmental factors (10). Several mechanisms appear to promote the accumulation of hepatic fat: De novo synthesis of triglycerides, impaired secretion of lipoprotein and, perhaps the most important in typical patients, increased delivery of fatty acids to the liver. These abnormalities correlate with central obesity and physical conditioning, providing the basis for conservative management of NAFLD with exercise, dietary changes, and weight loss. The prominent role of insulin resistance provides the basis for several of the most promising forms of pharmacologic intervention with insulin-sensitizing agents. Between these two broad categories of treatment, cytoprotective and antioxidant therapy remain under investigation as possible means of reducing oxidative injury.

Clinical and Histologic Criteria and Terminology Although the exact histologic criteria continue to be debated, the term NASH is now widely regarded as the more severe form of “NAFLD.” Not as widely accepted is the distinction between “primary” NASH (usually associated with obesity and diabetes without other precipitating factors) and “secondary” NASH (associated with a specific disease or some medications) (Table 39.1). This distinction is limited because shared risk factors point to a common pathogenesis of “primary” NASH and some of the conditions that have been associated with “secondary” NASH. The presence or absence of insulin resistance may be a useful distinguishing feature. As such, steatohepatitis associated with toxin exposure may qualify as a distinct entity while many other “secondary forms” may actually represent an exacerbation of “primary” NASH (See “Epidemiology” and “Other Conditions Associated with Nonalcoholic Fatty Liver Disease/Nonalcoholic Steatohepatitis—“Secondary” Nonalcoholic Steatohepatitis”).

Clinical Criteria By definition, the criteria for NASH require exclusion of alcohol as an etiology. The acceptable level of alcohol consumption is variable but the daily alcohol intake can be conservatively fixed as not exceeding 20 g/day in men and 10 g/day in women—levels below the risk level associated with increased risk of cirrhosis (30 g/day in men and 20 g/day in women) (11,12,13). However, these “cutoffs” leave an unresolved gray area in which a patient prone to NASH may consume alcohol P.1119 Sclose to the threshold for liver injury or may have consumed more significant alcohol (measured as lifetime exposure) in the past,

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leaving open the question of one chronic problem (NASH) superimposed on a past injury. These issues are further discussed in the subsequent text.

Table 39.1. Definitions and Terms

1. NAFLD. Indicates the presence of fatty infiltration of the liver, defined as fat exceeding 5%–10% of liver weight and frequently taken as fat in >5%–10% macrosteatotic hepatocytes in biopsy specimens. Microsteatosis is an underappreciated aspect because of limitations of routine staining techniques. The term NAFLD includes the term NASH. 2. Simple steatosis. A type of fatty infiltration (NAFLD) with no or minimal inflammation and no fibrosis. This is synonymous with type 1 disease, as classified by Matteoni (7) (see Table 39.2). 3. NASH. A type of NAFLD with inflammation, ballooned hepatocytes, and/or fibrosis, usually beginning around the central vein, which may progress to cirrhosis. This is synonymous with type 3 or 4 disease, as classified by Matteoni (7) (see Table 39.2). 4. “Primary” NAFLD or NASH. A term occasionally encountered in the literature but not uniformly accepted. It indicates typical NAFLD or NASH associated with central obesity and often type 2 diabetes mellitus but without a specific, additional etiology. The likelihood that many cases of “secondary” NAFLD or NASH represent unrecognized or exacerbated “primary” NAFLD or NASH makes the term less useful. 5. “Secondary” NAFLD or NASH. NAFLD or NASH associated with a specific problem such as a toxin. Use of the term secondary NAFLD or NASH implies the absence of insulin resistance. Many patients previously classified as “secondary” may have exacerbation of underlying “primary” NASH, making this distinction less useful. 6. “Presumed” NASH or NAFLD. Several epidemiologic and pediatric studies have utilized a presumptive diagnosis of NAFLD or NASH on the basis of abnormal liver enzyme levels, negative results of viral studies, and echogenic or “bright” liver on ultrasonography consistent with fatty infiltration. (See “Imaging in Nonalcoholic Fatty Liver Disease: Ultrasonography, Computed Tomography Scan, Magnetic Resonance Imaging and Magnetic Resonance Proton Spectroscopy”).

NAFLD, nonalcoholic fatty liver disease; NASH, nonalcoholic steatohepatitis.

Histologic Criteria Steatosis, defined as hepatic fat exceeding 5% to 10% of total weight (14) and usually taken as fat identifiable in more than 5% to 10% of hepatocytes by light microscopy, is an essential feature of NAFLD. Within the spectrum of NAFLD, the term NASH indicates a more severe type of liver injury and worse prognosis compared to “simple steatosis,” which is distinguished by the absence of inflammation or fibrosis and appears to have a long-term stable course (Fig. 39.1) (15). Beyond this distinction, even accomplished pathologists debate the relative importance of specific histologic variables (16). Interestingly, more or less restrictive definitions of the term NASH appear to influence patient demographics, suggesting the presence of gender-based variation in disease expression (17). Important histologic variables include fibrosis (usually sinusoidal in a pericentral vein or zone 3 distribution), ballooned hepatocytes sometimes containing Mallory hyaline and lobular inflammation (Figs. 39.2 and 39.3). Glycogenated nuclei are common (18,19). Other variables include portal injury, apoptotic bodies, microvesicular steatosis (much more evident using specialized fixation techniques such as osmium), and lipogranulomas (Figs. 39.3 and 39. 4) (20,21). Substantial concordance between observers has been reported for the extent of steatosis, location and severity of fibrosis, and balloon degeneration (22). The degree of fibrosis has been organized into a staging system developed by Brunt et al. (Table 39.2) (23). In addition, although not uniformly accepted, a useful histologic classification scheme (Table 39.2) for NAFLD has been proposed and is widely referenced. It ranges from simple steatosis to the more severe steatosis with balloon degeneration and Mallory bodies or fibrosis (7). Other scoring systems have also been proposed (24) but the most significant refinements in the histologic assessment has been the development of NASH activity P.1120 index (NAI) and NASH activity score (NAS), discussed further under “Scoring of the Biopsy (Nonalcoholic Steatohepatitis Activity Index, Nonalcoholic Steatohepatitis activity score).”

▪ Figure 39.1 Simple steatosis: The patient is a 47-year-old woman with mild obesity and an idiopathic, neurodegenerative disease and hepatomegaly. The biopsy specimen showed only minimal inflammation and no fibrosis. No inciting agents were identified to explain the liver condition (hematoxylin and eosin, 200×).

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▪ Figure 39.2 A: Nonalcoholic steatohepatitis (NASH) with cirrhosis (stage 4). B: Early stage 3 (bridging fibrosis) with hematoxylin and eosin stain. C: The same biopsy accentuating the presence of bridging with a Masson trichrome stain. The specimen in (A) is from a 65-year-old women with moderate obesity and type 2 diabetes. She does not have complications of portal hypertension. The presence of macrovesicular steatosis, inflammation, and cirrhosis allows the diagnosis of NASH with cirrhosis (stage 4) (100×, hematoxylin and eosin). Specimens (B) (200×, hematoxylin and eosin) and (C) (200×, trichrome) are from her 40-year-old son who has mild liver enzyme abnormalities and mild (mostly truncal) obesity (body mass index = 30) without diabetes. NASH with fibrosis, mildly apparent on the hematoxylin and eosin stain (B), is accentuated with trichrome staining (C), which demonstrates bridging consistent with stage 3. Arrowheads in (B) and (C) define a fibrotic bridge bordering a regenerative nodule. These slides also illustrate a familial pattern seen in approximately 20% of patients.

“Presumed” Nonalcoholic Fatty Liver Disease In several large epidemiologic studies, the diagnosis of “presumed NAFLD” has been made on the basis of noninvasive testing (See “Epidemiology”) (12). In general, such studies have utilized abnormal transaminases in the absence of other known liver disease and/or liver ultrasonography to make the diagnosis of fatty liver disease. However, the relationship between the diagnosis of “presumed” NAFLD and the histologic activity, stage, and prognosis is unreliable. Indeed, one of the major limitations of these studies is the inability to distinguish NASH from less severe forms of fatty liver such as simple steatosis.

▪ Figure 39.3 Balloon degeneration, Mallory hyaline, and glycogenated nucleus in nonalcoholic steatohepatitis. Long arrow indicates accumulation of perinuclear eosinophilic material (Mallory hyaline) in a ballooned hepatocyte (400×, hematoxylin and eosin). Agreement on what constitutes Mallory hyaline is sometimes hard to obtain. Ubiquitin stain, although infrequently used, can be employed to highlight Mallory hyaline (not shown). Also shown is a pale, glycogenated, nucleus (arrowhead), which is more typical of NASH compared to alcohol-related liver disease.

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▪ Figure 39.4 Micro- and macrovesicular steatosis in nonalcoholic steatohepatitis. Arrowhead indicates a cell with small droplets of fat in addition to the more apparent and typically large droplet in macrovesicular steatosis (long arrow, 400x, hematoxylin and eosin). Special stains or fixation techniques, such as osmium tetroxide fixation (not shown), can be used to accentuate the often overlooked microvesicular component.

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Cryptogenic Cirrhosis Serial biopsy studies have established the potential progression of NASH to a stage of “bland” cirrhosis with loss of characteristic histology (Fig. 39.5) (25,26). The loss of fatty infiltration may be due to altered blood flow or decreased sinusoidal permeability and impaired lipoprotein delivery as the liver becomes fibrotic (27,28,29). A number of additional studies have strongly suggested that many cases of “cryptogenic” cirrhosis, a remarkably homogenous group (Fig. 39.6), are the result of such a process (30,31,32,33,34,35,36,37,38). Approximately two thirds of patients with this diagnosis, among the most common indications for liver transplantation, have major risk factors for NAFLD (e.g., obesity and diabetes). In a series of patients undergoing transplantation for “cryptogenic” cirrhosis, definitive features of NASH were evident in 17 of 30 and minor features were seen in an additional 10 patients (39). The significantly increased frequency of steatosis and steatohepatitis after transplantation for cryptogenic cirrhosis further support this relationship (40). On the basis of these associations and predominant histologic findings (and recognizing that other conditions are also involved with cryptogenic cirrhosis), a classification system of cryptogenic cirrhosis can be formulated, as shown in Table 39.3 (41).

Table 39.2. Classification and Stages of Nonalcoholic Fatty Liver Disease/Nonalcoholic Steatohepatitis

Fibrosis Stages of NASH (Brunt et al. (23)) Stage 1: Zone 3, pericentral vein, sinusoidal or pericellular fibrosis Stage 2: Zone 3 sinusoidal fibrosis and zone 1 periportal fibrosis Stage 3: Bridging between zone 3 and zone 1 Stage 4: Regenerating nodules, indicating cirrhosis Types of NAFLD (Matteoni et al. (7)) Type 1: Simple steatosis (no inflammation or fibrosis) Type 2: Steatosis with lobular inflammation but absent fibrosis or balloon cells Type 3: Steatosis, inflammation, and fibrosis of varying degrees (NASH) Type 4: Steatosis, inflammation, ballooned cells, and Mallory hyaline or fibrosis (NASH)

NASH, nonalcoholic steatohepatitis; NAFLD, nonalcoholic fatty liver disease.

Focal Steatosis and Focal Sparing In a series of patients with various forms of fatty liver disease detected radiographically, focal steatosis was evident in approximately 15% and focal sparing (usually of the caudate lobe) was seen in 9% (42). Variation in blood flow (with resulting differences in P.1122 insulin exposure and nutrient delivery) is thought to explain both focal-sparing and focal steatosis (43,44). A relationship to insulin exposure has long been suspected as a factor because of the development of focal steatosis in continuous ambulatory peritoneal dialysis (CAPD) patients exposed to insulin in the peritoneal dialysis fluid (45,46). Histologically, the lesions vary from simple steatosis to steatohepatitis (45). Cirrhotic nodules have also been shown to occasionally have focal fatty change, possibly unrelated to fatty liver disease (47,48).

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▪ Figure 39.5 Development of nonalcoholic fatty liver disease (NASH) after transplantation for cryptogenic cirrhosis. A: Explanted liver from an obese, diabetic man showing “bland” cirrhosis (40×, hematoxylin and eosin). B: Two years later (200×, hematoxylin and eosin), a repeat biopsy for abnormal liver enzymes revealed steatosis that was persistent and associated with mild inflammation at 3 years (C) (200×, hematoxylin and eosin). D: Four years after transplantation the patient developed ascites and repeat biopsy showed early cirrhosis with bridging and diminished fatty infiltration (100×, hematoxylin and eosin). Long arrow demonstrates a fibrous band.

Historic Perspective Early Observations A long-recognized association between the liver and fat storage is mirrored in a popular explanation of the origin of the Latin term for liver, ficatum, and the corresponding modern Greek term, sycoti, both of which were derived from the common name for fattened animal livers, iecur ficatum and hepar sykoton, respectively (D. Tniakou, personal, P.1123 2005). A more scientific appreciation of fatty liver emerged in the 19th century when Virchow classified various types of fatty infiltration of the liver (49). The color, shape, and firmness of a fatty liver were described and fat-globules were proven to be within hepatic cells (50). Morgan, in the 1870s, described an association with obesity and overeating (51). This was extended many years later by Zelman, who reported the existence of liver damage with fibrosis and early cirrhosis in obese patients without a significant history of alcohol consumption (52). More recently, this concept resurfaced in patients who had undergone bypass surgery for morbid obesity (53,54,55,56,57,58). This was widely attributed at the time to postoperative, protein-calorie malnutrition or intestinal bacterial overgrowth, although a correlation between obesity and diabetes and potential liver damage was not strongly emphasized.

▪ Figure 39.6 Past series of patients with cryptogenic cirrhosis. Previous case series have shown a female predominance, onset in sixth or seventh decade, and mildly abnormal alanine transaminase (ALT) levels. [Series from references (30,31,32,33,34,35).]

Table 39.3. Cryptogenic Cirrhosis—Proposed Classification

Class 1—cirrhosis with features of steatohepatitis including scattered steatosis, ballooned hepatocytes, possibly with Mallory

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bodies, and glycogenated nuclei Class 2—cirrhosis with features of autoimmune disease including plasma cells or granulomas Class 3—cirrhosis with features of biliary obstruction including proliferation of bile ducts and cholestasis Class 4—bland cirrhosis: Cirrhosis lacking other distinguishing features

From Contos MJ, Cales W, Sterling RK, et al. Development of nonalcoholic fatty liver disease after orthotopic liver transplantation for cryptogenic cirrhosis. Liver Transpl 2001;7:363–373 and Ayata G, Gordon FD, Lewis WD, et al. Cryptogenic cirrhosis: clinicopathologic findings at and after liver transplantation. Hum Pathol 2002;33:1098–1104.

The Ethanol Conundrum As previously noted, the cutoff levels for classification of “nonalcoholic” versus “alcoholic” steatohepatitis (ASH) remain unresolved. Clearly, there are many patients with NASH and related cirrhosis without a history of current or past ethanol exposure (“teetotalers”). Before this recognition, a common experience was nicely summarized by Ludwig in his original description of NASH: “…we have encountered patients who did not drink, who had not been subject to bypass surgery, and who had not taken drugs that may produce steatohepatitis, yet had in their liver biopsy specimens changes that were thought to be characteristic of alcoholic liver disease. In these instances, the biopsy evidence sometimes caused clinicians to persevere unduly in their attempts to wrench from the patient an admission of excessive alcohol or to obtain a confirmation of such habits from relatives of the patients. Thus, the misinterpretation of the biopsy in this poorly understood and hitherto unnamed condition caused embarrassment to the patient and physician.”(2) Nonetheless, it is widely suspected and recently documented that approximately 10% of patients classified as having NASH actually have had a significant lifetime exposure to ethanol when a more structured P.1124 history is obtained (59). Intuitively, synergy between ASH and NASH seems likely by the association of more severe alcohol-related liver disease with obesity (60,61,62,63). However, one study has indicated a lower risk of severe steatohepatitis among obese patients consuming moderate alcohol, possibly mediated by effects on insulin signaling (64,65). Because of the widely perceived health benefits of moderate ethanol ingestion (e.g., red wine), the difficulty in sorting out NASH from alcohol-related liver injury is likely to persist. Immunohistochemical stains for insulin receptors and regulators may provide a means of distinguishing the prominence of one pathway over another but they have not been validated and clinical utility not yet confirmed (66). With the possible exception of glycogenated nuclei (increased in NASH), other histologic features do not reliably distinguish between ASH and NASH (18,67). A number of laboratory tests have been proposed to make this distinction including carbohydrate-deficient transferrin; however, none has proved satisfactory (68). Transaminase ratios may provide guidance: The aspartate transaminase (AST) to alanine transaminase (ALT) ratio is typically less than 1 in early or mild NASH, between 1 and 2 in more severe NASH, and more than 2 in more severe ASH (See “Clinical and Laboratory Findings”). The extent of elevation of γ-glutamyl transpeptidase (GGT) levels may also be useful (seldom >400 in NASH), but none of these relationships is entirely reliable and may be obscured by concomitant medication use. For these reasons, the history remains the most commonly used means of assessing alcohol consumption, especially when repeated by multiple health care providers over time.

“Hepatogenous” Diabetes Complicating the relationships between insulin resistance, hyperinsulinemia, and NAFLD is the relationship between liver disease and diabetes, which has long been referred to as hepatogenous diabetes (a term coined by Naunyn in the early 1900s) (69). The issue is whether hyperinsulinemia coincides with the development of liver disease, as appears to be the case in NAFLD, or follows the development of liver disease, as in hepatogenous diabetes. A number of papers have established an increased prevalence of diabetes in cirrhosis of various etiologies (70). Impaired insulin sensitivity rather than decreased insulin metabolism from portosystemic shunting, are postulated to explain this condition (71,72). The role of cirrhosis-related abnormal skeletal muscle metabolism, a major target of insulin and one of earliest abnormalities detectable in type 2 diabetes, is yet to be investigated (73).

Epidemiology and Prevalence in High-Risk Groups NAFLD is one of the most common of all liver disorders, especially in industrialized countries, and represents a significant source of disease (74,75,76,77,78,79,80). The estimated prevalence in the general population ranges from 2.8% to 20%, depending on the criteria used for estimation (81). In a series of 150 consecutive patients with abnormal liver enzymes for at least 6 months, 40% had steatosis, 15% had hepatitis C, and 2% had nonalcoholic steatohepatitis (82). In another series of 81 patients with abnormal liver enzymes and a negative serologic workup, 50% of the patients had steatosis and 32% had steatohepatitis (83). In the primary care setting, NAFLD accounts for approximately one third of cases of suspected chronic liver disease cases (84). Obesity, type 2 diabetes and hyperlipidemia have been the most constant conditions associated with steatosis and steatohepatitis and are predictors of more severe histologic disease (85). In a large study of risk factors for the presence of NAFLD at autopsy, Wanless and Lentz found mild to severe steatosis in approximately 70% of obese patients compared to 35% of lean patients and steatohepatitis in 18.5% of obese patients compared to just 2.7% of lean patients (86). Diabetes has also been identified as an independent risk factor for NASH. Bellentani et al. identified a 4.6fold increased risk of fatty liver in obese patients compared to nonobese patients and also identified hypertriglyceridemia as a significant predictor of steatosis on liver ultrasonography (12). An overview of major conditions associated with NAFLD and NASH is shown in Table 39.4.

Obesity Biopsy studies in obese patients (body mass index [BMI] usually >30) showed steatosis in 85%, mild to moderate fibrosis in approximately 25% to 30%, and cirrhosis in 1% to 2% (87,88). Ratzui et al. found that approximately 30% of consecutive obese patients with abnormal liver enzymes had at least septal fibrosis and 10% had cirrhosis (89). In another series of obese patients undergoing gastroplasty, Garcia-Monzon et al. observed NASH in 69%, while 22% had simple steatosis and only 8% had a normal biopsy (90). Similar to other studies, one half of those with mild or severe steatohepatitis had normal liver enzymes (91). In another group of patients undergoing bariatric surgery, Dixon et al. reported that only 4% had normal results of biopsies; 71% had simple steatosis and 26% had steatohepatitis with variable degrees of fibrosis (64). Similar results were noted in a more recent study. A compilation of histology in these series of obese patients is shown in Figure 39.7 (92).

Table 39.4. Conditions Associated with Nonalcoholic Fatty Liver

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Metabolic factors Obesity (especially truncal or central obesity) Type 2 diabetes mellitus Hyperlipidemia (especially hypertriglyceridemia) Systemic lipotoxicity Specific conditions associated with fatty infiltration of the liver Metabolic syndrome (hyperinsulinemia, hypertension, obesity, polycystic ovary disease) Lipodystrophy Mitochondrial diseases Weber-Christian disease Bariatric (weight loss) surgery Jejunoileal bypass (no longer performed) Gastric bypass or gastroplasty (less frequent compared to jejunoileal bypass) Medications Methotrexate Amiodarone Tamoxifen Nucleoside analogs Parenteral nutrition and malnutrition Total parenteral nutrition Kwashiorkor Celiac disease Miscellaneous Wilson disease Toxins (CCl 4 , perchloroethylene, phosphorous, ethyl bromide, petrochemicals)

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Type 2 Diabetes Mellitus Insulin resistance is common in patients with NASH, and hyperinsulinemia plays a pathogenic role in the progression of NASH even in the absence of overt diabetes (93,94). It is estimated that up to 75% of patients with type 2 diabetes have fatty infiltration (93,95,96), although ethnicity appears to influence the prevalence significantly (see subsequent text) (97). Fatty infiltration has been noted to commonly precede the development of overt diabetes in earlier studies (98). The progression to more overt diabetes in these patients depends on peripheral fat and skeletal muscle metabolism and pancreatic islet cell vitality. The severity of liver injury worsens with the degree of abnormal glucose metabolism among obese patients (99) and the impact on the overall clinical course is significant—the standardized mortality ratio in patients with type 2 diabetes is actually higher for cirrhosis than for cardiovascular disease (100,101). Younossi et al. further demonstrated that the coexistence of diabetes in patients with NAFLD more than doubled the prevalence of cirrhosis on diagnostic biopsy from 10% to 25% (102).

Hyperlipidemia As with type 2 diabetes, large studies revealing the true prevalence of NAFLD and associated histology within different forms of hyperlipidemia are lacking. In one study using noninvasive imaging, it was shown that two thirds of patients with hypertriglyceridemia and one third of those with hypercholesterolemia have fatty liver (103). This is probably an underestimation because significant hyperlipidemia (i.e., triglyceride, total cholesterol, or high-density lipoprotein [HDL] cholesterol) was reported in 96% of patients with NASH in one large, well-characterized series (104), although a lower range (3% to 92%) was noted in a compilation of 13 series summarized by McCullough (105). It is likely that ethnic, presumably genetic, factors will influence the true prevalence (see “Genetic Variation”). However, the close relationship between hyperlipidemia and fatty liver disease raises further practical concerns about the effects of antihyperlipidemic medications. Although acute hepatitis appears to be rare P.1126 among patients with suspected NAFLD treated with 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (See “Treatment of Nonalcoholic Fatty Liver Disease”), the long-term effects have not been adequately explored (106,107,108,109).

▪ Figure 39.7 Liver histology in series of obese patients. Only 10% of obese subjects have normal histology while 5% have previously unidentified cirrhosis. Approximately 85% have steatosis and one third of these have, in addition, nonalcoholic steatohepatitis (NASH) with varying degrees of fibrosis. (Adapted from findings in references 64,87,88,89,90,91,92.)

Metabolic Syndrome Unexplained elevation of liver enzyme levels, attributed largely to NAFLD, are seen in approximately 7% of individuals meeting the criteria for the metabolic syndrome, defined by the Adult Treatment Panel-III criteria (Table 39.5) (110,111). However, this is probably an underestimation of the true prevalence, given the high prevalence of NAFLD in the general population, the high prevalence of features of the metabolic syndrome among patients with NAFLD, and the frequency of normal liver enzymes even in the setting of significant

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histologic disease (the last factor obscures the true prevalence if NAFLD is detected depending on abnormal aminotransferases) (112). It has been suggested that NAFLD can cause metabolic syndrome. However, current data indicate that both hepatic steatosis and central adiposity are independent risk factors for metabolic syndrome and all three conditions appear to be united by variable degrees of insulin resistance and systemic lipotoxicity (see subsequent text) (113,114,115).

Normal Body Mass Index NAFLD has been well documented in patients with normal BMI (5,17,116). This group appears to contain relatively younger males with milder histology, visceral or central adiposity (without overt obesity by BMI), and hyperinsulinemia. Such individuals, possibly more common in Asian populations where visceral adiposity is seen with lower BMI, are thought to represent an initial stage of the insulin resistance syndrome (117,118,119,120). These findings are consistent with the major role of body fat distribution as opposed to simply the amount of body fat in the development of insulin resistance and NAFLD (121,122,123,124).

Table 39.5. Adult Treatment Panel-III Criteria for the Metabolic Syndrome (110)

Risk factor Abdominal obesity

Definition Waist circumference

Men

≥102 cm (≥40 in.)

Women

≥88 cm (≥35 in.)

Triglycerides

≥150 mg/dL

High-density lipoprotein cholesterol

Men

40 to 50 years), the degree of obesity, the degree of diabetes or insulin resistance, hypertriglyceridemia, hypertension, family history of NASH or cryptogenic cirrhosis, complete abstinence from ethanol, transaminase level (AST and ALT) elevation (relatively weak marker), and an AST to ALT ratio more than 1 are often, but not invariably, predictive of more advanced histology, but conflicting studies exist (5,7,30,60,64,76,85,89,90,91,205,279,280,281,282,283,284,285). Other factors noted as predictive of more severe histology on the initial biopsy specimen include circulating antibodies to lipid peroxides (286) and the number of parameters positive from the Adult Treatment Panel-III criteria for metabolic syndrome (287). A number of these variables have been combined into composite scores, but these also have limited sensitivity and specificity and have not gained wide clinical acceptance. Incorporation of markers of collagen metabolism, such as serum hyaluronic acid, into a clinical score enhances the predictive value but still carries only a 76% accuracy rate in predicting significant injury on biopsy (288).

Table 39.7. Predictors of More Severe Histology in Nonalcoholic Steatohepatitis

Age >40–50 y or female gender Degree of obesity or steatosis Hypertension Overt diabetes or increased insulin resistance Hypertriglyceridemia Elevated alanine transaminase level Elevated aspartate transaminase level Elevated γ-glutamyl transpeptidase level Aspartate transaminase:alanine transaminase ratio >1 Elevated immunoglobulin A level

See text.

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Limitations of the Biopsy The major limitations of biopsy include patient inconvenience, the potential for complications, performance in obese patients, and sampling error. In general, complication rates with liver biopsy are infrequent, and the variety of available techniques offer improved safety and applicability (289,290,291,292). Sampling error on percutaneous biopsy is well recognized but can be minimized by obtaining an adequate specimen more than 2 to 3 cm in length by 1.5 mm wide (15 to 16 gauge) (293,294,295). In the most convincing study, Ratziu et al. demonstrated a 10% to 15% risk of a two-stage error and roughly 40% risk of one-stage error in the fibrosis stage when specimens are less than about 2 to 3 cm in length (Fig. 39.11) (269).

Scoring of the Biopsy (Nonalcoholic Steatohepatitis Activity Index, Nonalcoholic Steatohepatitis Activity Score) Although the Brunt score remains the most commonly used method of assessing the biopsy, recent introduction of composite scores have provided a useful means of assessing response to treatment particularly in clinical investigations (Table 39.8). Key parameters have been combined into the NAI and NAS (297,298). The NAI ranges from 0 to 12 and accounts for steatosis, necroinflammatory activity, and hepatocyte injury (ballooned cells), each of which is scored from 0 to 4. The more refined NAS uses a scale of 0 to 8 P.1133

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to score steatosis, lobular inflammation, and cellular ballooning. Fibrosis stage is scored separately in both composites.

Table 39.8. Histology Scoring Systems in Nonalcoholic Fatty Liver Disease

Inflammation

Hepatocyte injury

Maximum

(lobular)

(ballooning)

score

Steatosis NAS-I (NAFLD

8

Fibrosis

0–3

0–3

0–2

0–4

0—none

0—no foci

0—absent

0—none

1—66%

periportal

3—>4 foci/mpf

3—bridging fibrosis

4—cirrhosis

NAI (NASH activity

0–4

0–4

0–4

12

0–4

0—50% of

2—perisinusoidal and

CVs

periportal

3—both z2 and z3,

3—bridging fibrosis

(1/3–2/3)

4—>75%

4—>2 foci/mpf

4—all zones (>2/3)

4—cirrhosis/regeneration

0–3

0–3

0–2

0—66%

3—>4 foci/mpf

2—many/prominent

2—perisinusoidal and

ballooning

portal/periportal

3—bridging fibrosis 4—cirrhosis

NAS, NASH activity score, nonalcoholic stestohepatitis; NAI, NASH activity index, nonalcoholic steatohepatitis; NAFLD, nonalcoholic fatty liver disease; z2, zone 2; z3, zone 3; mpf, medium power field—200× magnification; CVs, central veins.

Natural History and Prognosis Mortality Overview Although patients with NAFLD frequently have substantial comorbid conditions that could influence survival, progressive liver disease often becomes the dominant problem. Consistent with this, obesity was recognized as a major risk factor for cirrhosis-related deaths in people who consume little or no alcohol (299). Among patients with type 2 diabetes in Japan, the cause of death was cirrhosis in 6.4% (compared to 19.5% from heart disease) (300). However, the observed versus expected deaths ratio (O/E ratio) was actually higher for cirrhosis than for heart disease (2.67 vs. 1.81). In another report, the five- and ten-year survival in NASH was estimated at 67% and 59%, respectively (301). These figures were lower than those for a matched population, but the difference did not reach statistical significance. In a 12-year follow-up, Cortez-Pinto et al. showed that patients with NASH had a liver-related death rate similar to that for ambulatory patients with ASH—both rates were significantly better than those for hospitalized patients with ASH (302). In one of the largest natural history studies published to date, Adams et al. showed that liver disease is the third leading cause of death in a group of 420 patients with NAFLD followed up for a mean of 8 years compared to liver disease as the thirteenth most common cause of death in the general population (303,304).

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Variation Based on Initial Histology In a retrospective study of adult patients in the United States, the overall mortality among those with fatty liver accompanied by inflammation, fibrosis, balloon cells, or Mallory hyaline was increased compared to crude death rates, and cirrhosis-related deaths were also increased when fatty infiltration was accompanied by the presence of these more severe histologic markers (7). In contrast, several prior studies have shown that simple steatosis or steatosis with minimal inflammation (Matteoni type 1 and 2) is a relatively stable condition (15,305). The relative stability of these milder forms of fatty infiltration indicates that NASH (fatty infiltration plus fibrosis and/or balloon cells) probably begins at the higher stage rather than progressing through stages from simple steatosis to more severe forms. However, this has not been established and such a transition can be seen with rapid weight loss (and perhaps with other forms of metabolic stress) (306,307).

Serial Biopsy Studies A number of studies reporting serial biopsy in patients with NASH have now been published (5,25,26,89,308,309,310,311). Although the studies have a number of shortcomings, including variable biopsy techniques, different entry criteria, and incomplete data on confounding variables such as voluntary lifestyle changes and antidiabetic or antihyperlipidemic medications (312), there is sufficient data to draw some reliable observations. Compiling the studies, 177 patients have undergone a second biopsy after a mean of 4.5 years (Table 39.9). Cirrhosis developed in 10% of patients while fibrosis progressed in 33%, remained stable in 41%, and improved in 22%. In some of the patients, the progression to cirrhosis was surprisingly rapid over 1 to 2 years. Most papers show that as fibrosis progresses, aminotransferases, steatosis scores, and inflammation improve paradoxically. This is of some concern in the clinical setting in which normalization of the aminotransferases should be regarded with cautious optimism, especially in older patients. Normalization of these parameters is consistent with the progression of NASH to a “burned out” state, which is often recognized as “cryptogenic” cirrhosis (see preceding text).

Table 39.9. Serial Biopsies in Patients with Cryptogenic Cirrhosis

Years of follow-

Progressed to

Progressed to stage

No

Number

up

stage 4

2–3

change

Improved

Lee (1989) (308)

12

3.5

2

3

7

0

Powell (1990) (24)

13

4.5

3

3

6

1

Bacon (1994) (5)

2

5

1

0

1

0

Ratziu (2000) (89)

4

5

1

1

2

0

19

5.7

2

4

9

4

Fassio (2004) (309)

22

4.3

0

7

11

4

Adams (2005) (310)

98

3.2

9

24

35

30

177

4.5

18 (10%)

59 (33%)

Author

Harrison (2003) (308)

Totals/Average

73

39

(41%)

(22%)

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Nonalcoholic Steatohepatitis–Related Cirrhosis and Cryptogenic Cirrhosis NASH-related cirrhosis appears, like other forms of cirrhosis, to progress through several stages. A small number of studies have addressed the natural history of this form of cirrhosis. Hui et al. compared the course of 23 patients with well-defined NASH cirrhosis to 46 matched patients with cirrhosis from hepatitis C (313). Nine of 23 patients with NASH–cirrhosis developed major complications of portal hypertension (e.g., ascites, encephalopathy, and variceal bleeding) during a mean follow-up of 7 years, with complication-free survival of 83%, 77% and 48% at 1, 3 and 10 years, respectively. Ratziu et al. compared the course of 27 overweight patients with cryptogenic cirrhosis to 10 lean patients with cryptogenic cirrhosis and 391 patients with hepatitis C–related cirrhosis in a retrospective follow-up cohort study (314). With a mean follow-up of 22 months, 2 of the 15 patients presenting only with abnormal liver test results developed major complications of portal hypertension and 5 developed HCC. The overall severity and risk for either a complication of portal hypertension or HCC were greater in obese patients with cryptogenic cirrhosis compared to the lean cryptogenic cirrhosis group but not different from patients with hepatitis C. The authors concluded that obesity-related cirrhosis behaves as aggressively as hepatitis C–related cirrhosis.

Hepatocellular Cancer A number of studies have now shown an increased risk of HCC in obese patients and in those with diabetes (315,316,317,318,319). In addition to the natural history studies noted in the preceding text, there are also a number of well-documented NASH case reports and series indicating this progression (320,321,322). Although animal models of fatty liver exist in which HCC develops without cirrhosis, most human studies suggest that silent progression of NASH to cirrhosis is the more predominant pathway (323,324). The association of NASH with cryptogenic cirrhosis (see preceding text) and the risk of HCC in cryptogenic cirrhosis further strengthens the idea that for many patients with progressive NASH, HCC is an increasingly common late complication (325,326,327). Although the molecular events leading to HCC are yet to be fully defined, the proliferation of oval cells (hepatocyte progenitor cells) observed in human and experimental NAFLD may be a contributing factor (328) in addition to mutations in regulator genes such as PTEN that regulate certain aspects of both fat metabolism and cell proliferation (329).

Experimental and Animal Models of Nonalcoholic Fatty Liver Disease Small Animal Models Many advances in the understanding of NAFLD have resulted from the development of small animal models—usually mice or rats. This field has been reviewed extensively by Koteish and Diehl (330), Farrell (331), and Nanji (332). Several of the best known models include

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the hyperphagic ob/ob mouse, which has a congenital deficiency of leptin; the FA/FA rat, which has an impaired leptin receptor; and the methionine–choline–deficient (MCD) rodent. Studies in these animals, as well as the numerous transgenic models, have led to many seminal observations in NASH about hepatic fat metabolism and its regulation. Although providing insight into specific pathways, these models share the common problem of inadequately imitating the common form of human NAFLD. For example, the ob/ob mouse requires other provocative measures to produce significant injury in addition to simple steatosis, and the MCD model, although producing hepatic injury without further provocation, lacks insulin resistance (333).

Large Animal Steatosis and the Liver as a Normal Fat-Storing Organ Fatty liver disease is a well-known problem in veterinary medicine. Variants of the disorder are seen in cows (334,335,336), hens (337), and cats (338,339) and can occur spontaneously or with phosphorous supplements in pigs (340,341,342). Hepatic “lipidosis” is reported to be one of the most common liver disorders in domestic cats and, similar to human steatohepatitis, has been associated with mitochondrial morphologic abnormalities (343). Seasonal variation in hepatic fat has been observed in deer (344). These observations suggest a close integration of the liver into the adipose system, which is evident experimentally in studies demonstrating the upregulation of genes governing adipocyte differentiation during liver regeneration (345,346). Palmipedes (migratory geese) develop fatty liver before migration and utilize fat as a preferred source of energy for muscles through the expression of fatty acid–binding protein (347). This has been exploited in the production of foie gras in which geese are fed a corn-based diet, resulting in a 8- to 10-fold increase in liver size in as little as 2 weeks (from 100 to 800 g). The goose hepatocyte enlarges to three to four times the original diameter, with fat droplets observable as mixed micro- and macrosteatosis. Although early harvest limits the natural course, degenerative changes P.1135 is seen and cirrhosis is anecdotally noted (348). In addition, accidental exposure to moldy corn (mycotoxins) is associated with liver failure with ascites (349). Interestingly, significant subspecies variation exists in the lipogenic capacity (350). Indirect evidence suggests that the main mechanism involves increased lipid synthesis and altered very low density lipoprotein (VLDL) synthesis and secretion (351,352,353). These observations further illustrate the role of the liver within a broadened concept of the adipose system, with its inherent plasticity (transdifferentiation of fat stores) and its role in energy metabolism and thermoregulation (354,355,356,357). It has been hypothesized that skeletal muscle fat metabolism, which interacts with hepatic fat stores and strongly influences insulin sensitivity, confers a survival advantage under harsh conditions (358).

Pathogenesis of Nonalcoholic Fatty Liver Disease and Nonalcoholic Steatohepatitis Although many of the metabolic abnormalities noted in NAFLD have yet to be assimilated into a cohesive “story,” the importance of lipotoxicity as underlying insulin resistance, the metabolic syndrome and cellular injury in steatohepatitis, is emerging as the most likely primary pathway in typical cases of human NAFLD (359). In this light, NAFLD can be viewed as a potential adverse occurrence within the realm of the metabolic syndrome and more specifically as a possible adverse outcome of systemic lipotoxicity (360). Excessive fatty acids have a broad effect on many tissues and even influence gene expression and, hence, adipocytokine production in adipose tissue (361). However, it is very likely that there is substantial variation between groups or individuals in the relative importance of different mechanisms, as suggested in the wide ethnic variation in the development of steatosis—the first “hit” in the path to hepatic fibrosis. A plausible pathway for some of the most common abnormalities is shown in Figure 39.12.

Steatosis The normal, healthy liver contains no more than 5% lipid by weight (362). The levels of both triglycerides (mostly unsaturated fatty acids) and free fatty acids (mostly saturated) are increased in the liver of obese patients (363). The development of cellular injury involves a cascade of events beginning with the development of steatosis (NAFLD) and the subsequent development of oxidative stress, lipid peroxidation, and cell injury, and activation of profibrotic cytokines, resulting in NASH (364). Increased hepatic fat stored in the form of triglyceride can be derived from the plasma fatty acid pool mostly released from peripheral adipose tissue by lipolysis, from dietary fat through chylomicron remnants, or from de novo synthesis within the liver. De novo lipid synthesis, largely from glucose, is governed by two main transcription factors that signal transcription of the enzyme systems responsible for fatty acid synthesis and subsequently for their esterification into triglyceride: Sterol regulatory element–binding protein (SREBP), which is governed by insulin, and carbohydrate response element–binding protein (CREBP), which is governed by glucose levels (365,366,367,368). SREBP-1 level appears to be increased in animal models of NAFLD, and it is suspected that a similar process is going on human NAFLD. The disposition of fatty acid in the liver proceeds by one of several routes: Storage as triglyceride, export as VLDL, or oxidation. Regulation of the predominant form of disposition depends on a number of interacting factors based on energy homeostasis and influenced by peroxisome proliferators activated receptor (PPAR) activity and probably by the activity of the adrenergic nervous system (369,370,371). Although focal fat necrosis may occur from direct release of fat from swollen hepatocytes in NAFLD (372), toxicity, as noted by Bass and Merriman, results primarily from the indirect effects of lipid peroxidation and to a lesser extent from direct toxicity of fatty acids (369).

Insulin Resistance Although epidemiologic work indicates that peripheral insulin resistance is neither sufficient nor essential for NAFLD, it is present in most patients with NAFLD and, therefore, is so closely intertwined with the disease as to be virtually inseparable in most cases. Insulin resistance is characterized by a reduced sensitivity to insulin in target tissues (e.g., muscle, adipose tissue, and liver), where it normally favors glucose transport into the cell, storage of glycogen, inhibition of lipolysis in adipose tissue, and inhibition of gluconeogenesis from the liver. The expected manifestations of insulin resistance include decreased peripheral (muscle) glucose utilization, enhanced lipolysis and mobilization of fatty acids from peripheral fat stores, and increased hepatic glucose output (normally suppressed by insulin). Insulin resistance, primarily mediated by excessive fatty acids (373,374,375,376,377,378,379), is observed in NAFLD using a variety of techniques (112,380,381,382). The relationship between fatty liver and insulin resistance represents a (sometimes precarious) balance between the three main target organs—skeletal muscle, adipose tissue, and the liver (383). Using modifications of the insulin “clamp” test, Sanyal et al. convincingly demonstrated that the predominant site of resistance in NAFLD is in the peripheral fat and skeletal muscle as opposed to the liver (94,384,385,386,387). Recent work using MRS of skeletal P.1136 muscle indicates that insulin resistance in metabolic syndrome results from skeletal muscle lipotoxicity and secondary changes in mitochondrial metabolism (388). Excessive skeletal muscle fatty acid also leads to inhibition of insulin-stimulated glucose transport through the effects on insulin receptor substrate-1 (IRS-1) (389). Teleologically, insulin resistance in this setting can be seen as a normal response to excessive energy substrate availability (diet and obesity) and underutilization (activity).

Lipid Peroxidation and Hepatic Lipotoxicity Lipid peroxidation reflects an imbalance between pro- and antioxidant substances (oxidative stress) (390). It is a branching, chain reaction stimulated by a free radical attack on unsaturated fatty acids (Fig. 39.12) (391). Free radicals, which initiate the process, may be derived from mitochondrial, peroxisomal, or cytochrome P-450 fat metabolism, with the formation of superoxide, hydrogen peroxide, and hydroxyl radicals. The products of the reaction are another free radical and a lipid hydroperoxide, which, in a reaction catalyzed by iron, forms a second (lipid) free radical and, therefore, amplifies the process. Damage involves chemical bonding with other cellular constituents including membrane lipids, proteins, and DNA (392). Although difficult to measure directly, lipid peroxidation is the main process leading to inflammation, activation of cytokines, stimulation of stellate cells, and fibrosis (393,394). Levels of the markers of

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lipid peroxidation (e.g., nitrotyrosine, 4-hydroxynonenal [4-HNE], and malonic dialdehyde [MDA]) are increased in human NASH and are associated with mitochondrial abnormalities (94,395,396). The latter may be an injury response or due to increased activity of uncoupling protein (UCP), which decreases oxidative stress and is associated with abnormal oxidative phosphorylation and an adenosine triphosphate deficit (94,270,397,398,399,400). Cytokine level elevation activates stellate cells with secondary fibrosis. Interestingly, a major site of oxidative injury appears to be the border area of small fat droplets that consist of a unique phospholipid monolayer (401,402).

Cytokine Activation and Fibrosis Cytokine level elevation, especially tumor necrosis factor-α (TNF-α), has been well described in NAFLD (403). In animal models, obesity itself appears to sensitize the liver to cytokine-mediated injury (404,405), TNF-α has been shown to induce mitochondrial UCP in regenerating liver in animal models of nonalcoholic fatty liver, and transforming growth factor-β (TGF-β) and interleukin-6 (IL-6) have also been implicated as mediators of fibrosis in NASH (403,406,407). Cell culture experiments indicate that stimulation of TNF-α results from fatty acid–mediated destabilization of lysosomes (408). Indirect evidence suggests that lipoperoxide-induced expression of inflammatory cytokines is mediated by the transcription factor nuclear factor-κB (409). A number of additional transcription factors (e.g., PTEN) and cytokines (e.g., osteopontin) are being recognized that, at least in experimental conditions, appear to interact with each other and influence insulin signaling and fibrosis pathways (410,411,412).

Adiponectin and Leptin (Adipocytokines) Adiponectin is the most abundant protein in the adipocyte and participates in glucose homeostasis and insulin signaling through receptors in the muscle (adipoR1) and liver (adipoR2) (413,414,415,416,417). Its level is decreased in both obese/diabetic mice and humans and in patients with NASH compared to body fat–matched controls (416,418,419). Unlike leptin (see subsequent text) or TNF-α, adiponectin levels appear to be significantly different in patients with simple steatosis versus those with NASH, suggesting a more significant role for it in disease pathogenesis including a possible anti-inflammatory effect (420,421,422,423). Leptin is a circulating protein coded for by the obesity gene (chromosome 7q31 in humans) and produced primarily in white adipose tissue and its level is increased in cirrhosis (424,425,426,427). Its primary role is to govern satiety through action at the hypothalamus; however, human obesity is usually associated with elevated leptin levels (428). It has been variably implicated in the development of histologic injury in human and experimental NAFLD (429,430,431,432,433). In a recent study from Angulo et al. elevated leptin levels in progressive NASH were attributed to factors involved in production; no difference in leptin was seen between patients with worsening injury or those without on serial biopsy (434).

Other Cellular Injuries (Ballooning and Apoptosis) Although the ballooned hepatocyte constitutes a marker for more progressive injury, a consensus definition remains elusive. The normal diameter of the hepatocyte varies from 13 to 30 µm (435). On light microscopy, ballooned cells are described as 1.5 to 2 times the normal size, located predominantly in zone 3 compared to other zones, and have rarefied cytoplasm. Ballooning in viral hepatitis involves hydropic changes and irregular dilatation of the smooth endoplasmic reticulum (436,437). However, electron microscopy using osmium fixation, which highlights fat droplets, suggests that most such cells in NASH P.1137 P.1138 are microsteatotic (438). Coupled with observations of localization of lipid peroxidation (see preceding text) and localization of Mallory bodies (439), these observations suggest that handling of small-droplet storage fat is a significant source of injury in NASH. Apoptotic bodies are only occasionally seen in NASH specimens, although signal pathways for apoptosis are significantly activated in human NASH (440). This paradoxical situation is the result of rapid “cleanup” of apoptotic bodies such that they are infrequently seen or it may represent the result of a (sometime precarious) balance of pro- and antiapoptotic factors involving adaptive changes in the mitochondrion that play a central role in the regulation of apoptosis (441,442,443). Such adaptive (or maladaptive) changes may make the fatty liver more resilient in terms of localized cell death but more prone to necrosis because these processes are closely interrelated and coregulated (444).

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▪ Figure 39.12 Mechanism of steatohepatitis—increased hepatic fat stores result from increased delivery of fatty acids, increased de novo synthesis, and decreased export of fat. The excessive free fatty acids both result from and promote extrahepatic insulin resistance. Fatty acid oxidation leads to the formation of free radicals, which derive from mitochondrial, peroxisomal, and cytochrome P-450 oxidation. Free radicals (e.g., super oxide, hydrogen peroxide, and hydroxyl radical) can directly activate transcription factors, resulting in overexpression of cytokines and, if not neutralized by the antioxidant system (superoxide dismutase and glutathione peroxidase), the free radicals (X • ) can trigger the chain reaction of lipid peroxidation (rancidification). Unsaturated, polyenoic fatty acids are especially susceptible. This produces a carbon-centered lipid radical, which reacts with oxygen to form an oxygen-centered lipid peroxyl radical. This substance subsequently reacts with a second fatty acid to form another lipid free radical (propagation) and a lipid hydroperoxide. The latter is unstable and, in the presence of iron and another fatty acid, reacts to form yet another lipid radical (amplification). Alternatively, the lipid hydroperoxide may degrade to malonic dialdehyde (MDA) (detected by the thiobarbituric acid reactant [TBAR] reaction) or to ethane or pentane (detected in breath tests), react with other radicals to form a stable pigment (e.g., ceroids and lipofuscins), or may cross-link with deoxyribonucleic acid (DNA) or other cellular proteins (neoantigen formation). This oxidative stress induces cytochrome P-450 fatty acid oxidation and causes mitochondria changes with enlargement and formation of crystalline bodies possibly a result of abnormal expression of uncoupling protein. This leads to an adenosine triphosphate (ATP) deficit that increases the risk of necrosis and probably stimulates apoptosis, resulting in sporadic cell death and increased cell turnover. Lipid peroxidation also causes transcription of profibrotic cytokines that activate stellate cells, producing fibrosis. Countering the process of lipid peroxidation is the antioxidant system, which neutralizes lipid radicals by combination with vitamin E. The latter is then restored by shuffling the radical groups to glutathione through selenium. GSH, glutathione; NADPH, nicotinamide adenosine dinucleotide phosphate, reduced form; GSSG, oxidized glutathione; IgA, immunoglobulin A.

Mitochondrial Changes and Adenosine Triphosphate Homeostasis The mitochondrion may be both an especially important source of reactive oxygen species and a target for injury resulting from lipid peroxidation (196,445,446). Its unique evolutionary history places it in a central position of several major metabolic pathways, including fatty acid synthesis and β-oxidation, oxidative phosphorylation (ATP generation), and signaling pathways for the process of apoptosis (447). Mitochondrial morphologic abnormalities (Fig. 39.13) have been observed in both ASH and NASH (94,229,448,449,450). Commonly noted intramitochondrial inclusions are thought to be either a protein or phospholipid precipitate (451). It is thought that these morphologic abnormalities correlate with functional abnormalities, including respiratory chain dysfunction, and by their distribution may be part of the adaptive process to oxidative stress that make the liver more tolerant to reactive oxygen species but more susceptible to ischemic injury (398,452,453). For example, the poor function of steatotic livers in transplantation has been attributed in part to abnormal ATP homeostasis with depletion of electron transport components and increased susceptibility to ischemic injury (454,455,456,457). Impaired function of the mitochondrial electron transport chain (ETC) in NAFLD has been described in several studies (458,459), attributable in part the to overexpression of UCP induced by increased fatty acids (460). Perez-Carreras et al. noted reduction in the ETC activity to 40% to 70% of normal in all the major complexes (I to V) in human NASH. In vivo impairment of ATP synthesis was observed by Cortez-Pinto et al. using

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P MRS of the liver in controls compared to patients P.1139

with NAFLD (Fig. 39.14) (270). In experimental conditions, complex I and V (ATP synthase) dysfunction have been implicated in reperfusion injury, and these results open inquiry as to what the optimal protective mechanism is for the ETC during liver transplantation. (461,462). In a recent exhaustive review of the subject, Pessayre and Fromenty proposed that NASH is primarily a “mitochondrial disease.” Although this may initially seem to be an overstatement, a cogent argument is presented on the fundamental role of the mitochondrion in hepatic fat metabolism, skeletal muscle physiology, insulin resistance, and pancreatic islet cell vitality, placing the mitochondrion at a central point in the overall pathophysiology of NAFLD (463).

▪ Figure 39.13 Deformed mitochondria with crystalline inclusions in nonalcoholic steatohepatitis: A: An elongated mitochondrion with two bundles of parallel, crystalline structures (arrows) near a large fat droplet. B: Two mitochondria cut tangentially showing crystalline inclusions in an area of cytoplasm between two large fat droplets (arrows). Note the paucity of normal cristae.

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▪ Figure 39.14 Abnormal adenosine triphosphate (ATP) homeostasis in nonalcoholic fatty liver disease. Initial fructose metabolism requires the expenditure of energy in the form of ATP. Intravenous injection of fructose normally produces a significant drop in hepatic ATP stores, as measured by magnetic resonance spectroscopy, followed by return to baseline. The baseline in patients with fatty liver is similar to that in healthy controls, but there is a blunted recovery indicating the presence of a relative energy deficit in the fatty liver. NS, not significant. (Adapted from Cortez-Pinto, Chatham J, Chacko VP, et al. Alterations in liver ATP homeostasis in human nonalcoholic steatohepatitis: a pilot study. JAMA 1999;282:1659–1664.)

Cytochrome P-450 Similar to alcohol-related liver disease, induction of cytochrome CYP 2E1 in NAFLD has been described as a possible source of oxidative stress and activation of cytokines (464,465,466) through enhanced microsomal ω-oxidation of fatty acids (normally a minor pathway of fatty acid metabolism). Expression of CYP 2E1 is influenced by a high-fat, low-carbohydrate diet and colocalizes in immunohistochemical stains to fatty cells and markers of lipid peroxidation (467,468). It is associated with increased activity of mitogen-activated protein kinases (MAPKs) through the activity of extracellular signal–regulated kinases 1 and 2 (ERK1/2), which participate in the regulation of cell death (apoptosis) pathways (469). On the basis of animal studies, it is unlikely that P-450 2E1 plays a singular role in NASH because CYP 2E1 nullizygous, transgenic mice also develop a steatohepatitis-like picture (470). Indeed, Schattenberg et al. (469) showed experimentally that overexpression of CYP 2E1 is protective against oxidative injury and decreases apoptosis but increases the risk of necrosis induced by fatty acid exposure. Consistent with this adaptive process, inhibition of CYP 2E1 in experimental conditions increases formation of Mallory bodies (471).

Abnormal Lipoprotein Metabolism Consistent with its close association with hyperlipidemia and metabolic syndrome, NASH has been associated with abnormal apolipoprotein (apo) metabolism (472). Two groups have reported decreased apoB-100 secretion in NASH, indicating possible impairment of VLDL synthesis (a major component of which is apoB-100) (473,474), and another group has described differences in apoA-I (a component of HDL) in patients with NAFLD compared to controls (475). Isolation of small lipid droplets from hepatocytes of rats in experimental studies has demonstrated that the lipid droplets P.1140 are composed of neutral fats consisting mainly of esters of linoleic, oleic, and palmitic acid (24). Similar studies in human liver biopsy samples from patients with ASH have shown that the lipid composition of accumulating lipid droplets is similar regardless of size but that the smallest droplets, based on size, density, and lipid composition, resemble a precursor of plasma VLDL (476,477). Taken together with observations of cellular ballooning (see preceding text), these observations again point to the abnormal handling of the small storage lipid droplets as being significant in NASH progression.

Peroxisomal Metabolism The peroxisome is involved in numerous metabolic pathways including synthesis of plasmalogens, bile acids, and cholesterol, and oxidation of very long chain fatty acids, branched-chain fatty acids, dicarboxylic acids, polyunsaturated fatty acids (PUFA), L-pipecolic acid, and phytanic acid (478,479). Steatohepatitis develops in mice lacking peroxisomal fatty acyl-CoA oxidase (480), and morphologic abnormalities with diminished size but increased number of microsomes have been described in human fatty liver (481). Peroxisomal fatty acid oxidation represents another potential source of reactive oxygen species including superoxide and hydrogen peroxide that form during peroxisomal oxidation of very long chain fatty acids and metabolism of dicarboxylic acids (derived from cytochrome P-450 ωoxidation of very long chain fatty acids) (482). Multiple inherited disorders of peroxisomal metabolism have been described including Zellweger's syndrome, adrenoleukodystrophy, and Refsum's disease. Although disturbed peroxisomal metabolism does not appear to be a primary factor in most patients with NASH (based on normal levels of dicarboxylic acid (94) and normal very long chain fatty acid profiles in patients with NASH—Caldwell et al.), it is possible that genetic abnormalities, nutritional abnormalities, or adaptive changes in the peroxisome may contribute to the condition in some patients.

Other Conditions Associated with Nonalcoholic Fatty Liver Disease/Nonalcoholic Steatohepatitis—“Secondary” Nonalcoholic Steatohepatitis The foregoing discussion has largely centered on what some refer to as “primary” NASH or NAFLD typically associated with insulin resistance and the metabolic syndrome. The presence of other factors may suggest a separate disease with overlapping features of NASH (Tables 39.1 and 39.4) distinguished primarily by the lack of insulin resistance. However, this does not exclude the likelihood that many such patients have underlying “primary” NASH exacerbated by some other insult.

Bariatric Surgery Historically, weight-reduction therapy played an important role in the recognition of NAFLD/NASH because of the unexpected exacerbation that was noted in some patients after early jejunoileal bypass (483). Stimulation of TNF by bacterial endotoxin has been postulated as an etiologic factor, but this was not supported by efforts to prevent injury using oral antibiotics (484) or by reports of a similar process after gastroplasty, in which bacterial overgrowth is less of a problem (485). Micronutrient deficiency has also been proposed. The rate of weight loss may be a key factor by increasing the rate at which intra-abdominal fat is mobilized. In spite of its historical association with exacerbation of NASH, weight loss surgery (particularly gastric bypass) remains a viable option in some patients (see subsequent text).

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Medication Induced A number of medications have been implicated as causes of steatohepatitis. In several cases, particularly with nifedipine and diltiazem (486,487), the association may be one of common drug use in patients at high risk for NASH. Similarly, Chitturi and Farrell pointed out in a recent paper that the risks for methotrexate-induced steatohepatitis are almost identical to those of NASH, suggesting a high degree of overlap between these entities (466,488). Tamoxifen-induced steatohepatitis presents a particularly difficult balance of risk–benefit in patients on therapy for prior breast cancer (489,490). Although liver injury was not considered a side effect in a recent review of adjuvant breast cancer therapy (491), the authors and others have observed severe steatohepatitis with cirrhosis in this setting (492,493,494). The risk factors for tamoxifen-induced steatohepatitis are, as with methotrexate, similar to those of NASH, suggesting a possible synergistic effect of the drug in a patient prone to NASH. Amiodarone, which has long been associated with phospholipidosis and steatohepatitis (495,496,497), has become an extremely common medication in cardiology. As with tamoxifen, its use should not be undertaken without some consideration of the high likelihood that many recipients will have preexisting fatty liver because of shared risks between NASH and heart disease. The issue again becomes one of risk versus benefit. We have observed advanced cirrhosis with death due to P.1141 liver failure in this setting and associated litigation. To our knowledge, an adequate risk–benefit analysis has not been done.

Human Immunodeficiency Virus Therapy An acquired lipodystrophy, associated with insulin resistance and steatosis and sharing features with multiple symmetrical lipomatosis, has been described with nucleoside analog therapy for human immunodeficiency virus (HIV) infection (on highly-active antiretroviral therapy [HAART]) (498,499,500,501). The syndrome may be increased in women, may present acutely, and can be associated with a Reye's syndrome–like picture, neuropathy, myopathy, and pancreatitis (502). There are increased concerns that patients with this syndrome are at increased risk of developing NAFLD and the possibility of progression to NASH and cirrhosis. The pathogenesis of NAFLD from HAART therapy is related to insulin resistance (383), mitochondrial DNA damage (503), and the development of lactic acidosis (504).

Parenteral Nutrition, Malnutrition, and Celiac Disease Liver disease, often with macro- and microvesicular steatosis, is one of the most common and potentially severe side effects of total parenteral nutrition (TPN) (505). In one series of patients on extended TPN, macrovesicular steatosis was seen in 63% of patients with cholestasis and 100% of those without cholestasis (506). Microvesicular steatosis and phospholipidosis (fat-laden cells in the sinusoidal space or portal tract) are also common features. Both the amount of lipid infusion and its composition appear to affect the expression of liver disease in this setting (507). Choline deficiency may play a role in some patients. At the opposite end of the nutrition spectrum, fatty liver is a common finding in kwashiorkor, in which export of lipid from the liver because of protein deficiency (diminished apoprotein B) is thought be the primary mechanism (508). In both types of nutritional fatty liver, zone 1 (periportal) involvement may predominate. There have been reports suggesting an association between NASH/NAFLD and celiac disease (509,510,511). Bardella et al. examined 59 consecutive patients with elevated transaminase levels and NAFLD and found that 6 patients had positive tissue transglutaminase antibodies and 2 (3.4%) were positive for antiendomysial antibodies. Overall, two patients (3.4%) were positive for both antibodies and had positive histology (512). In another report, Nehra et al. observed that 1 out of 47 patients with NASH was positive for antiendomysial antibodies (514).

Solvents and Industrial Agents A variety of toxins have been implicated in the development of fatty liver diseases (514). Better described agents include carbon tetrachloride (now rarely used), dimethylformamide, perchloroethylene, and petrochemical derivatives (515,516,517,518). Other compounds and elements that have been implicated include phosphorous (See “Experimental and Animal Models of Nonalcoholic Fatty Liver Disease”), ethyl bromide, ethyl chloride, and rare earths. Synergy between exposure to these agents and disease progression in an obese patient and/or a patient with diabetes is suspected but not established. Cotrim et al. have demonstrated a potentially progressive form of NAFLD that results from petrochemical exposure and occurs in the absence of insulin resistance (519).

Wilson Disease Macro- and microvesicular steatosis are well-known features of Wilson disease (520,521). Consideration of Wilson disease should be made especially with steatohepatitis in a younger individual. It is not known how often the carrier state for mutations in the nuclearencoded gene for copper-transporting ATPase (522) could play a role in more typical cases of NASH. We have noted borderline values of ceruloplasmin occasionally in patients with some features of obesity-related steatohepatitis (S. Caldwell, unreported clinical observation, 2004). Mitochondrial injury, mutations, and premature oxidative aging were recently described in patients with Wilson disease, suggesting a possible overlap (through mitochondrial dysfunction) with more typical NAFLD and NASH (523).

Inherited Metabolic Diseases Macrovesicular steatosis can be seen in a variety of inherited metabolic diseases, most, but not all, of which present in childhood. Disorders include glycogen storage diseases (524), galactosemia (525), tyrosinemia (526), heterozygous hypobetalipoproteinemia (527,528), and abetalipoproteinemia. Both of the latter disorders are characterized by impaired formation of VLDL due to decreased synthesis of apolipoprotein B. A number of lipid storage diseases, (e.g., cholesterol ester storage, Niemann-Pick disease, Tay-Sachs disease, and Gaucher's disease) can have excessive fatty infiltration of the liver with cholesterol esters, sphingolipids, phospholipids, sphingomyelin, gangliosides, or glucocerebrosides. Presentation as systemic diseases in infancy (although not exclusively so) and the distribution (predominantly in the reticuloendothelial cells) distinguish the lipid storage disorders from typical NAFLD/NASH (21,529). P.1142

Managing the Obese Patient with Diabetes and Cirrhosis Silent progression of NASH to cirrhosis, often in association with normalization of the liver enzymes, has led to the common situation in which otherwise stable patients with type 2 diabetes are found incidentally to have cirrhosis (299,312). Although early data indicates that therapy aimed at diabetes may ameliorate steatohepatitis (See “Antidiabetic Agents”), there is little knowledge on the effects of other commonly employed medications such as antidepressants, sulfonylureas, HMG-CoA reductase inhibitors, or even insulin itself. Moreover, other adjunct treatments that are commonly used in these patients (e.g., aspirin for coronary disease or angiotensinconverting enzyme inhibitors for prevention of diabetic kidney disease) may have adverse effects if cirrhosis has developed (530). This situation arises because of the insidious development of the hyperdynamic state of cirrhosis as a result of portosystemic shunting. One of the hallmarks of this striking change in physiology is systemic vasodilatation with associated changes in renal hemodynamics. Therefore, in addition to considering disease-specific conditions such as the possibility of varices or HCC, broad treatment considerations need to include a reconsideration of certain tenets of diabetes management. Unfortunately, this aspect of NAFLD has not been adequately investigated.

Treatment of Nonalcoholic Fatty Liver Disease Who Should be Treated?

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Patient selection and the relative risk–benefit of different interventions remain one of the most challenging aspects of treating NAFLD. Although less severe forms of NAFLD, such as simple steatosis or steatosis with only inflammation (types 1 and 2 NAFLD), may progress to cirrhosis, most studies support an increased risk of progression, mainly in the presence of more severe histology at baseline such as ballooned cells and fibrosis (NASH or types 3 and 4 NAFLD) (7,15,305,309,531,532). These data indicate the need for careful patient selection in studying the effects of as yet unapproved pharmacologic interventions (Table 39.10). In general, there is a consensus that dietary changes and increasing activity are cornerstones and that these lifestyle changes are typically part of standard recommendations in spite of limited data and variable acceptance by the patient (see subsequent text). Voluntary adoption of these recommendations complicate the interpretation of pharmacologic therapy—most of the existing publications have lacked controls and, although most have included anthropometric indices such as weight and some have accounted for dietary changes, none has accounted for the degree of conditioning that could influence steatosis and may not be reflected in anthropometric measurements.

Endpoints of Therapy The primary endpoint of therapy remains changes in the histology (See “Scoring of the Biopsy (Nonalcoholic Steatohepatitis Activity Index, Nonalcoholic Steatohepatitis activity score)”). However, sampling error, especially with cores less than 2 cm, is a potential problem and few of the studies reviewed in the subsequent text have provided sufficient details of the biopsy to account for this confounding variable (269,293,294,295). Novel markers of histologic injury especially applicable to the research setting include stains for lipid peroxide by-products, electron microscopy to assess mitochondrial morphology, and markers of stellate cell activation (557). The major surrogate markers for liver injury include the serum aminotransferase levels (approximation of inflammatory activity), imaging to assess hepatic fat content (e.g., ultrasonography, CT scan, MRI, MRS), and serologic fibrosis panels that are in development. Other important measures include anthropometric indices (e.g., weight, BMI), the degree of physical conditioning (e.g., lactate threshold), measures of insulin signaling (e.g., glucose tolerance testing, HOMA or Quicki, insulin clamp tests), serologic or urinary markers of lipid peroxidation (e.g., malondialdehyde or hydroxynonenal), and cytokine levels such as TNF-α, TGF-β, and adiponectin.

Initial Intervention Lifestyle changes remain a cornerstone of initial management (558,559,560). Optimistically, diet modification and exercise can be accomplished in obese patients, with as many as 80% of patients achieving dietary goals and 36% achieving exercise goals (561). Pessimistically, even intensive counselling to reduce fat intake ( Table of Contents > Volume 2 > Section VIII - Vascular Diseases of the Liver > Chapter 40 - Vascular Diseases of the Liver

Chapter 40 Vascular Diseases of the Liver Mical S. Campbell Mark A. Rosen Thomas W. Faust

Key Concepts z

z

Budd-Chiari syndrome occurs as a consequence of thrombotic occlusion of hepatic venous outflow. Hypercoagulable states account for most cases of Budd-Chiari syndrome. Anticoagulation is the mainstay of medical management.

z

Webs and membranes in the inferior vena cava develop from prior thrombosis and represent the most common subtype of Budd-Chiari syndrome in the Far East.

z

Acute or subacute Budd-Chiari syndrome may present with abdominal pain, hepatomegaly, and ascites, whereas symptoms and signs of portal hypertension are prominent with chronic disease.

z

Doppler ultrasonography is a useful noninvasive screening test for BuddChiari syndrome. Contrast-enhanced computed tomography and magnetic resonance imaging can also demonstrate hepatic vein occlusion and associated parenchymal abnormalities secondary to venous outflow obstruction. Venography and liver biopsy remain the gold standard for diagnosis.

z

Angioplasty and thrombolysis may be of benefit in highly selected cases. Decompressive surgery and transjugular intrahepatic portosystemic shunt are often reserved for progressive liver disease despite medical management. Liver transplantation may be performed for patients with decompensated cirrhosis or acute liver failure.

z

Hereditary hemorrhagic telangiectasia, also known as Rendu-Osler-Weber syndrome, is a multisystemic vascular disorder that may involve the liver.

z

Peliosis hepatis is characterized by blood-filled cystic lesions in the hepatic parenchyma, which may occur in the setting of immunosuppression or human immunodeficiency virus (HIV) infection. Bartonella henselae is the cause of bacillary peliosis hepatis in patients with HIV infection.

Budd first described a clinical triad of abdominal pain, ascites, and hepatomegaly in 1845 (1). Chiari later provided pathologic correlation (2). Today, Budd-Chiari syndrome refers to the thrombotic obstruction of the hepatic venous outflow system. Occlusion may occur in hepatic venules, hepatic veins, and the inferior

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vena cava up to the right atrium. Budd-Chiari syndrome must be distinguished from other causes of hepatic venous outflow obstruction, including right heart failure and veno-occlusive disease. In the Far East, occlusion of the inferior vena cava with webs and membranes is more common, whereas in the West, hepatic vein thrombosis is typical. Hypercoagulable states are responsible for most cases of Budd-Chiari syndrome, and anticoagulation is the mainstay of medical treatment. Clinical presentation is variable and may depend on the extent and speed of occlusion, as well as the development of collateral circulation. Acute, subacute, P.1172 chronic, and asymptomatic presentations have all been well described. Hepatic venography is the diagnostic standard and is of value when contemplating surgical or percutaneous shunting. In the absence of rigorous, prospective studies, treatment algorithms are difficult to define. Angioplasty and thrombolysis may be used in highly selected patients. Transjugular intrahepatic portosystemic shunt (TIPS) and surgical decompression are options for progressive liver disease despite anticoagulation and other medical therapy. Patients with decompensated cirrhosis or acute liver failure may require liver transplantation. Hereditary hemorrhagic telangiectasia (HHT), also known as Rendu-Osler-Weber syndrome, is characterized by presence of epistaxis, mucocutaneous telangiectasias, and visceral arteriovenous malformations. Hepatic involvement is variably present but is usually asymptomatic. Hepatic arterial embolization has been used for symptomatic disease, but recent experience highlights the dangers of this approach. Peliosis hepatis is characterized by cystic, blood-filled lesions in the liver. It occurs in patients who are immunosuppressed or have human immunodeficiency virus (HIV) infection. Bartonella henselae is the causative agent of bacillary peliosis hepatis associated with HIV. Treatment of these generally asymptomatic lesions consists of either administering antibiotics to treat Bartonella infection or addressing the underlying cause of immunosuppression.

Budd-Chiari Syndrome and Related Disorders Etiology The most frequent causes of venous obstruction are prothrombotic disorders, particularly myeloproliferative diseases (3,4,5) (Table 40.1). In one of the largest series, 45% of patients with Budd-Chiari syndrome had polycythemia rubra vera and 9% were diagnosed with essential thrombocythemia (6). Occult myeloproliferative states, demonstrated by spontaneous endogenous erythroid colony formation in the absence of erythropoietin stimulation, are also common (7). An increasing number of thrombotic disorders have been associated with Budd-Chiari syndrome (8,9,10,11,12,13). In over 25% of cases, more than one thrombophilic state may be present (13). Careful, systematic evaluation for prothrombotic disorders has lowered the proportion of cases labeled as idiopathic to less than 10% (7,13,14). Factor V Leiden mutation is the most frequent cause of hereditary thrombophilia and is thought to be the second most common cause of thrombotic occlusion of the hepatic veins and vena cava (8,9,10,11,12,13,14,15,16,17,18). Other hypercoagulable states associated with Budd-Chiari syndrome include antiphospholipid antibody syndrome, paroxysmal nocturnal hemoglobinuria, prothrombin G mutation, methylene-tetrahydrofolate

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reductase mutation, antithrombin III deficiency, and deficiencies of protein C and protein S (13,15,19,20,21,22,23,24). Patients who are pregnant or are taking oral contraceptives and develop Budd-Chiari syndrome usually have an underlying thrombophilic state (8,9,10,11,12,13,14,15,16,17,18).

Table 40.1. Etiology of Budd-Chiari Syndrome

MYELOPROLIFERATIVE DISORDERS

LOCAL COMPRESSION

Polycythemia rubra vera Essential thrombocytosis

Neoplasms Infection

Occult myeloproliferative disorders

OTHER HYPERCOAGULABLE STATES

SYSTEMIC DISEASES

Factor V Leiden mutation Prothrombin G20210A gene mutation

Behçet's disease Inflammatory bowel

Antiphospholipid antibody syndrome Methylene-tetrahydrofolate reductase

disease Sarcoidosis

mutation Paroxysmal nocturnal hemoglobinuria

Idiopathic

Protein C and S deficiency Antithrombin III deficiency Oral contraceptives Pregnancy

Frequently more than one condition may be present.

Local compression by adjacent tumor, abscess, or inflammation may lead to a secondary Budd-Chiari syndrome. Neoplasms associated with outflow obstruction include primary hepatocellular, renal, adrenal, pulmonary, pancreatic, and gastric carcinomas (25,26,27,28,29). Benign and malignant vascular neoplasms arising within the hepatic veins or vena cava (e.g., cavernous hemangiomas, leiomyomas, leiomyosarcomas, and rhabdomyosarcomas) have also been associated with Budd-Chiari syndrome (30,31,32,33). Other rare causes of hepatic venous outflow obstruction have been identified. Bacterial, viral, and parasitic infections; collagen vascular diseases; inflammatory bowel disease; and Behçet's disease may result in venous occlusion (29,34,35,36,37,38,39,40,41,42).

Inferior vena cava thrombosis Budd-Chiari syndrome includes thrombosis anywhere along the hepatic venous outflow tract. It has been proposed that obstruction principally affecting the inferior vena cava should be termed obliterative hepatocavopathy (43). Primary inferior vena cava thrombosis appears to be more common in India, China, Japan, Nepal, and South Africa for unclear reasons. Compared to classic P.1173 Budd-Chiari syndrome, obliterative hepatocavopathy is more often considered idiopathic (43,44,45,46,47). It has also been found in association with hepatocellular carcinoma (43,44,45,46,47). However, systematic investigation

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frequently reveals an underlying thrombophilic state (44,48). The obstruction results from caval webs or membranes, which may also involve the ostia of the hepatic veins. Although the lesions were formerly thought to be congenital, it is now recognized that they represent the transformation of inferior vena cava thrombosis (43,49). Widespread acceptance of obliterative hepatocavopathy as a distinct entity has not occurred because its etiology, prognosis, and management are similar to those of classic Budd-Chiari syndrome (Table 40.2) (50).

Occlusion of the terminal hepatic venules (venoocclusive disease) Veno-occlusive disease refers to obstruction of the hepatic sinusoids or small intrahepatic veins. In contradistinction to Budd-Chiari syndrome, occlusion is not thrombotic but results from fibro-obliterative endophlebitis (Table 40.2). Occasionally, Budd-Chiari syndrome may involve only small intrahepatic veins. Sparing of the large hepatic veins can be seen with allergic phlebitis, granulomatous disease, paroxysmal nocturnal hemoglobinuria, and other thrombophilic states (13,50). Distinction from veno-occlusive disease can generally be accomplished by recognition of etiology and in some cases by demonstration of clot. Outside the setting of bone marrow transplantation, the two conditions may be indistinguishable. Initial reports of veno-occlusive disease were attributed to ingestion of herbal teas containing large quantities of pyrrolizidine alkaloids (51,52). Today, venoocclusive disease is seen almost exclusively in the setting of bone marrow transplantation, and the reader is referred to Chapter 60 for a detailed review. Hepatotoxic agents, particularly certain chemotherapeutic conditioning regimens, account for most cases (Table 40.2). Recipients of liver and renal allografts and patients exposed to azathioprine are also at risk for developing veno-occlusive lesions. Other rare conditions associated with veno-occlusive disease include vitamin A toxicity; arsenic poisoning; exposure to insecticide; administration of 6-thioguanine, intra-arterial 5-fluoro-2′-deoxyuridine, Thorotrast, and a combination of norethisterone with conditioning chemotherapeutic agents (51,53,54,55,56,57).

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Table 40.2. Budd-Chiari Syndrome Subtypes and Veno-Occlusive Disease

CLASSIC BUDD-CHIARI SYNDROME Thrombosis principally of hepatic veins More common in western countries Thrombophilic state most common etiology OBLITERATIVE HEPATOCAVOPATHY Webs and membranes (representing prior thrombosis) in inferior vena cava More common in China, Nepal, India, Japan, and South Africa Thrombophilic state, idiopathic and hepatocellular cancer common VENO-OCCLUSIVE DISEASE Nonthrombotic fibrosis of hepatic sinusoids and small intrahepatic veins Almost exclusively seen in the setting of bone marrow transplantation Mainly caused by conditioning chemotherapy

Pathology Hepatic venous outflow obstruction is caused by thrombotic occlusion of the terminal hepatic venules, hepatic veins, or inferior vena cava. Generally, the disease is silent if only one hepatic vein is occluded. Obstruction may manifest as fibrous cord remnants of hepatic veins, short-length stenoses, membranes, webs, or occlusions of the hepatic venous ostia (19,43,49,58). In acute Budd-Chiari syndrome, the liver appears enlarged, smooth, and red purple because of congestion. In chronic disease, direct outflow from the caudate lobe to the inferior vena cava may compensate for venous outflow obstruction of major hepatic veins, resulting in caudate lobe hypertrophy with atrophy and cirrhosis of the remaining segments (59). In some cases caudate lobe hypertrophy may obstruct the intrahepatic portion of the inferior vena cava. Histologic changes may be uneven and result in liver biopsy sampling errors. Centrilobular congestion and sinusoidal dilatation are seen with acute obstruction, whereas atrophy, necrosis, and centrizonal hepatocyte dropout with extension to periportal regions are associated with severe injury. Venous stasis and congestion lead to hypoxic damage and oxidative injury to hepatocytes (60,61). In chronic disease, there is complete obliteration of the central veins associated with centrilobular fibrosis that may culminate in cirrhosis (62,63,64). Periportal fibrosis may be more prominent if branches of the portal vein are concomitantly thrombosed because of stasis (65). Large, regenerative nodules are also commonly reported in areas exposed to a compensatory increase in arterial blood flow (60,65).

Clinical Presentation About two thirds of patients with Budd-Chiari syndrome are women, with onset of symptoms usually in the late 30s (6,66). Clinical presentation is variable and depends on the extent and rate of outflow obstruction, as well as the development of collaterals (19,62) (Table 40.3). Presentation may range from P.1174 an asymptomatic state to fulminant hepatic failure, or to cirrhosis with

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complications of portal hypertension (15,29,67,68). More than 85% of patients have hepatomegaly and ascites, whereas esophagogastric varices and splenomegaly may be seen in 40% to 60% of individuals (67). The presence of dilated subcutaneous veins over the body and trunk are more often associated with inferior vena cava obstruction (43,69). Acute obstruction is commonly accompanied by right upper quadrant abdominal pain, nausea, vomiting, hepatomegaly, and ascites (67). Jaundice and splenomegaly may be present with acute occlusion but are usually mild. Rarely, massive hepatocellular necrosis with acute hepatic failure may follow rapid and complete occlusion of all major hepatic veins (29,67). A subacute presentation of less than 6 months is characterized by vague right upper quadrant discomfort, hepatomegaly, mild-to-moderate ascites, and splenomegaly (67,68). Jaundice is either absent or mild. Chronic Budd-Chiari syndrome of greater than 6 months’ duration generally presents with progressive ascites. It may also be accompanied by other complications of portal hypertension, such as bleeding varices, encephalopathy, coagulopathy, renal insufficiency, fatigue, and muscle wasting (19,29,62,67,68). Generally, cirrhosis is found only in patients with chronic disease. However, the demonstration of cirrhosis in biopsy specimens taken from patients with acute outflow tract obstruction provides argument that the current classification system leaves room for improvement (47,70).

Table 40.3. Clinical Manifestations of Budd-Chiari Syndrome

Right upper quadrant pain Hepatomegaly Ascites Splenomegaly (rare) Jaundice Acute liver failure (rare) Weight gain Nausea and vomiting Pleural effusions Lower-extremity edema Complications of portal hypertension

Diagnostic Evaluation Laboratory investigation Standard laboratory investigation is rarely helpful in patients with Budd-Chiari syndrome. Nonspecific mild transaminase level elevation can be seen in 25% to 50% of patients but does not aid in establishing the diagnosis (25,37). Transaminase values over 1,000 IU/L are possible in acute outflow obstruction or hepatic failure, especially if there is accompanying portal vein thrombosis (25). Serum bilirubin and alkaline phosphatase levels and prothrombin time are usually normal or mildly elevated and are also not specific (25,71,72). Ascitic fluid analysis is consistent with portal hypertension. Myeloproliferative and thrombotic disorders are common. Therefore, systematic, comprehensive evaluation for hypercoagulable disorders should be undertaken. The following tests should be performed: Plasma clotting factors and inhibitors, factor V Leiden factor

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mutation, prothrombin G gene analysis, antiphospholipid antibodies and lupus anticoagulant, flow cytometry for paroxysmal nocturnal hemoglobinuria, blood smear analysis, and in select cases determination of total red cell mass, bone marrow biopsy, and measurement of serum erythropoietin levels (50,62). Caution must be exercised in the interpretation of protein C, protein S, and antithrombin III because compromised hepatic synthetic function may provide alternative explanations.

Medical imaging Doppler ultrasonography allows for noninvasive evaluation of the hepatic veins, inferior vena cava, and portal vein. In experienced hands the sensitivity of ultrasonography for detecting venous obstruction approaches 85% to 95% (15,19,73). Real-time evaluation of acute venous occlusion reveals enlarged, stenotic, or tortuous hepatic veins, whereas the major hepatic veins of patients with chronic disease may not be seen (73,74,75,76). Intrahepatic venous-tovenous spider web collaterals and/or the presence of intrahepatic or subcapsular hepatic venous collaterals are highly suggestive of Budd-Chiari syndrome (50,73,74). Ultrasonography may also show caval compression by a hypertrophied caudate lobe or obstruction of the vena cava by thrombus, tumor, or membranes (73,74,75,76). Visualization of a caudate vein is over 90% specific for Budd-Chiari syndrome, although only 50% sensitive (77). The addition of Doppler to conventional ultrasonography increases sensitivity. Doppler is effective for evaluating not only the perihepatic vascular anatomy but also the direction of blood flow and site of obstruction. Loss of the normal triphasic wave variation in the vena cava or hepatic veins has a sensitivity of 88% for occlusion (78). Computed tomography (CT) scan and magnetic resonance imaging (MRI) are complementary investigations to Doppler ultrasonography (79,80,81,82). Abnormalities seen may include nonvisualization of vessels or obstruction by thrombus (73,76,83,84,85). Acute thrombus may be demonstrated as an expanded nonenhancing vein (Fig. 40.1), whereas more chronic changes are suggested when vessels are narrowed or not visualized. A “mosaic” pattern of abnormal parenchymal enhancement (Fig. 40.2), representing the effects of relative venous outflow obstruction, is commonly seen P.1175 in contrast-enhanced CT and MRI. This pattern is not specific for Budd-Chiari syndrome and can also be seen in severe right-sided heart failure. In cases of chronic venous outflow obstruction, parenchymal changes of nodular regeneration (including macroregenerative nodules) and cirrhosis may ensue (Fig. 40.3) (76,78,84,86). When portal hypertension develops, characteristic imaging findings (e.g., splenomegaly, ascites, collateral vessels) are often depicted as well.

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▪ Figure 40.1 Gadolinium-enhanced magnetic resonance imaging of a 67year-old woman with Budd-Chiari syndrome and acute hepatic decompensation. Delayed post gadolinium images demonstrate expanded nonenhancing left hepatic vein (arrow), representing acute thrombus. A narrowed but enhancing middle hepatic vein is also shown (arrowhead). Vessel narrowing suggests prior thrombosis with recanlization. Portal vein thrombus and ascites were also present. Patient decompensated and underwent transplantation. Explant pathology confirmed acute left hepatic vein thrombus. The middle and right hepatic veins with chronic thrombotic changes and recanalization were also demonstrated.

Venography remains the standard of reference for diagnosis and is key to planning optimal therapy. Typical venographic findings include narrowed, irregular hepatic veins with or without occlusive thrombi. Thrombi may be found either at the junction of the hepatic veins with the cava or just distal to the venous orifices (25,29,72). Replacement of hepatic veins with the classic “spider web” appearance, intrahepatic collaterals, and recanalized veins can also be appreciated (25,29,72,78,87). Angiographic assessment of the vena cava provides important information about the location and extent of obstruction, as well as its amenability to angioplasty and stenting (25,29,71,72,87). Both catheter-based and magnetic resonance venography (Fig. 40.4) can be used to depict stenoses or webs of the inferior vena cava. Local installation of thrombolytics may be performed at the time of venography in patients with fresh clots (less than 3 to 4 weeks) (88). Liver biopsy may also be obtained at the time of catheter venography. Furthermore, pressure measurements obtained at the time of venography can provide useful information before surgical decompression (25,29,71,72,87).

Liver biopsy Although not mandatory, liver biopsy is complementary to medical imaging and clinical patient assessment. Generally, the diagnosis can be established by medical imaging. In select patients, biopsy may be required to distinguish BuddChiari syndrome from veno-occlusive disease or cirrhosis from other causes.

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Biopsy specimens may establish the presence of fibrosis and cirrhosis and may also grade the severity of hepatocellular necrosis. However, caution should be used when interpreting results because sampling error is common. Bilobar biopsy may provide a higher diagnostic yield (87). However, it is not clear whether results from liver biopsy determine the prognosis (89,90,91). In one multivariate analysis, age, Child-Pugh score, responsiveness to diuretics, and creatinine were predictive of survival. Data from carefully documented P.1176 biopsies did not predict survival (90). A follow-up study found that diagnosis of acute or chronic Budd-Chiari syndrome, as opposed to acute on chronic injury only, was an important prognostic indicator for survival (91).

▪ Figure 40.2 Gadolinium-enhanced magnetic resonance imaging (MRI) of a 57-year-old woman with chronic Budd-Chiari syndrome and prior transjugular intrahepatic portosystemic shunt. The MRI demonstrates heterogeneous (mosaic) enhancement in the left lobe (A) and portions of the right lobe (B).

▪ Figure 40.3 Magnetic resonance imaging of the liver of a 31-year-old man with long-standing Budd-Chiari syndrome. In the T2-weighted image (A), liver parenchyma is abnormally edematous, with signal intensity elevation

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(comparable to that of spleen). Multiple regenerative nodules characteristic of long-standing Budd-Chiari syndrome are hypointense to the edematous liver parenchyma. In the postgadolinium image (B), nodular enhancement heterogeneity is shown. A portion of the thrombosed left hepatic vein is demonstrated (arrow). Ascites is also noted (asterisk).

Management In the absence of prospective natural history studies of untreated and unselected patients and randomized, controlled trials of treatment options, firm management recommendations cannot be made; however, some general principles have emerged. Anticoagulation is recommended for most patients. Thrombolytics may be of benefit in fresh thrombosis. Angioplasty with or without stenting may be considered for focal obstruction. If symptoms are progressive despite medical therapy, then decompressive therapy with TIPS or surgical shunting is advised. Some investigators recommend decompressive procedures early in the course or if extensive necrosis is seen on liver biopsy. Generally, liver transplantation is reserved for acute liver failure or decompensated cirrhosis.

Medical therapy Early series demonstrated poor survival in untreated Budd-Chiari syndrome; most patients died within P.1177 3 years of diagnosis (25,72). More recent studies show improved survival. In one study, 5-year survival was 50% before 1985 and 75% afterwards (90). Widespread adoption of anticoagulation with warfarin is thought to be the cause of this improved trend. It seems prudent to recommend anticoagulation even in the absence of an identifiable prothrombotic state. It is possible that in some patients with myeloproliferative disorders, hydroxyurea and aspirin may be more appropriate (92). Patients with ascites should be placed on low-sodium diets and diuretics. Responsiveness to such measures is an independent predictor of survival (90,91). If ascites is not easily controlled after anticoagulation and medical therapy, patients should then undergo decompressive therapy.

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▪ Figure 40.4 Cardiac-gated bright-blood (cine) vascular imaging 2 cm below (A) and at (B) the level of the hepatic vein confluence of a 20-yearold man with lower extremity swelling and liver dysfunction. In (A), a patent inferior vena cava (IVC) with flow is demonstrated (arrowhead). In (B), the IVC is narrowed. Dark areas within IVC lumen represent turbulent (nonlaminar) flow. Cavogram (not shown) demonstrated IVC stenosis with thrombus, severely narrowing the lumen with a large pressure gradient. Angioplasty relieved both lower extremity symptoms and hepatic abnormalities. Repeat cine magnetic resonance imaging in the sagittal plane after angioplasty (C) demonstrates a patent IVC with mild structuring at the site of prior stenosis.

In carefully selected patients with clots no older than 3 or 4 weeks, the prompt administration of thrombolytics (e.g., streptokinase, urokinase, or recombinant tissue plasminogen activator) has been effectively used to dissolve thrombi and relieve hepatic congestion (88,93,94). Thrombolysis may be more effective when thrombolytics are administered locally into the hepatic vein and combined with angioplasty with or without stenting (88).

Interventional radiology Percutaneous transluminal balloon angioplasty has been used to treat focal stenoses of the inferior vena cava and/or hepatic vein (95). Although excellent short-term results are achievable, sustained patency rates of only 50% are seen at 2 years (96). Wire-, laser-, or needle-assisted angioplasty is appropriate for stenoses refractory to standard techniques (97,98). For salvage of failed angioplasty or as primary therapy for focal stenoses, percutaneous intraluminal stenting is an option (19,96,97,98). More than 80% of stents remain patent 3 years after placement, with good control of symptoms (19,99). Stenting has also been used to treat intrahepatic inferior vena cava obstruction caused by compression from caudate lobe hypertrophy, which would otherwise preclude portacaval shunting. After stenting, portacaval shunting has been successfully performed (100). TIPS is being increasingly used as an alternative to decompressive surgical procedures because it is less invasive and does not carry the high perioperative mortality associated with surgical shunting. TIPS may have a role as a bridge to transplantation for patients with end-stage liver disease and ascites refractory to diuretics and sodium restriction (101,102,103,104) or in patients who present with fulminant hepatic failure (101,102,103,104,105,106). Recent series have reported on the use of TIPS after progressive, symptomatic liver disease with ascites despite anticoagulation and medical therapy. Control of symptoms, improvement of Child-Pugh class, and good 5-year survival without liver transplantation (74%) have been reported after TIPS (66,70). Survival after TIPS compares favorably with historical controls from surgical series. Shunt dysfunction often develops over time because of thrombotic occlusion. Therefore, surveillance with ultrasonography or angiography and chronic anticoagulation are recommended (70,102,106). Recent introduction of polytetrafluoroethylenecoated stents may dramatically reduce TIPS thrombosis. In one study, only 33% of patients with covered stents experienced dysfunction after TIPS within 1 year of the procedure, compared to 87% of patients with bare stents (107).

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Surgical decompression There is currently a divergence of opinion about whether surgical decompressive procedures should be offered early in the course of Budd-Chiari syndrome or should be reserved for patients who have progressive symptomatic disease despite medical therapy. One approach emphasizes the role of liver biopsy in determining which patients should undergo early surgical shunting. Anticoagulation alone is recommended if biopsy reveals only centrilobular congestion and sinusoidal dilatation, whereas surgery is reserved for those with hepatocyte necrosis (71,108). A second strategy advocates early surgical decompression, regardless of biopsy findings. Presumably, early relief of hepatic congestion may prevent ongoing necrosis and fibrosis. Such a strategy is supported by recent studies that found carefully collected data from liver biopsy to be not predictive of prognosis (89,90). Furthermore, in one retrospective study after adjustment for case severity, surgical shunting was associated with improved outcomes (89). If biopsy does not predict outcome, but performance of a surgical shunt does, then perhaps early surgery is preferable. However, caution must be exercised because no rigorous prospective study has been performed to test this strategy. A third treatment approach has been increasingly used. Patients are first treated medically with anticoagulation and diuretics if ascites is present. If symptoms and serum tests of hepatic synthetic function do not improve within days for subacute Budd-Chiari syndrome and within weeks for slower presentations, then decompressive shunting is advised. Patients selected for surgery exhibited a nonsignificant trend toward improved survival (6). Similar treatment strategies using TIPS in place of surgical decompression have achieved excellent results (66,70). Success with TIPS has led to recommendations that decompressive surgery be relegated to third-line therapy. Moreover, surgical decompression is associated with high perioperative mortality (5% to 30%) and cannot be safely P.1178 performed for patients with Child-Pugh class B or C cirrhosis (19,50,70). The authors offer their own therapeutic algorithm (Fig. 40.5).

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▪ Figure 40.5 Proposed algorithm for management of Budd-Chiari syndrome. TIPS, transjugular intrahepatic portosystemic shunting.

A variety of portosystemic shunts is available to relieve sinusoidal hypertension of Budd-Chiari syndrome. Side-to-side portacaval shunts have been successfully used to convert the portal vein into an outflow tract (15,25,29,71,82,109). A pressure gradient of more than 10 mm Hg between the portal vein and the inferior vena cava is required for adequate shunt flow. For patients with compression of the intrahepatic portion of the inferior vena cava by a hypertrophic caudate lobe, inferior vena cava shunting may not be possible. Mesocaval shunts between the superior mesenteric vein and vena cava provide effective portal decompression for these patients (25,29,37,108). As with the side-to-side approach, caval pressure must be considerably lower than portal pressure. Shunt thrombosis remains a problem for 20% to 55% of patients who receive mesocaval shunts (15,37). Other shunts have been described, including splenocaval, cavoatrial, hepaticoatrial, and mesojugular shunts (110,111). Interposition synthetic grafts are also occasionally used. Finally, transatrial membranotomy with finger fracture or excision may be effective for patients with fenestrated membranes (29,37,112,113).

Liver transplantation Liver transplantation is the preferred treatment for patients with Budd-Chiari syndrome and either acute liver failure or decompensated cirrhosis (15,29,37,87,109,114,115). Patients with significant liver disease who decompensate after receiving decompressive shunts or those with shunt failure

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may be rescued with transplantation (112). Excellent 5-year patient and graft survival have been achieved, with rates similar to those for patients undergoing transplantation for other diseases (116,117). Transplantation is curative for protein C, protein S, and antithrombin III deficiency. All patients should receive indefinite anticoagulation for hypercoagulable states not curable by liver replacement (115). Aspirin and hydroxyurea effectively reduce platelet aggregation and number, respectively, and may be appropriate for preventing recurrent thrombosis after transplantation in patients with underlying myeloproliferative disorders (92,118). Patient selection is critical because individuals with short life expectancies due to underlying medical conditions are not appropriate for transplantation. However, most underlying myeloproliferative and other disorders associated with Budd-Chiari syndrome have near normal 10year P.1179 life expectancies, which should not preclude transplantation (117). It is possible that immunosuppression could accelerate malignant transformation after transplantation, but this has not yet been reported.

Liver Involvement in Hereditary Hemorrhagic Telangiectasia HHT, also known as Rendu-Osler-Weber syndrome, is a multisystemic vascular disorder that variably affects the liver. Curacao criteria require presence of three of the four following criteria for definitive diagnosis: Recurrent and spontaneous epistaxis, multiple mucocutaneous telangiectasias, visceral arteriovenous malformations, and diagnosis of HHT in a first-degree relative (119). The disease is autosomal dominant and exhibits age-dependent penetrance. Identification of endoglin (ENG) and activin receptor-like kinase (ALK-1) gene mutations have allowed subclassification of HHT into types 1 and 2 (120,121). Both ENG and ALK1 encode membrane glycoproteins expressed on vascular endothelial cells involved in vascular remodeling (122). Patients affected with HHT1 tend to have ENG mutations and are more likely to have pulmonary arteriovenous malformations. HHT2 is associated with ALK-1 mutations and is often clinically milder and more commonly associated with hepatic involvement. Retrospective studies suggested radiologic evidence for hepatic involvement in only 8% to 30% of patients with HHT (123,124). However, a recent prospective study using multiphasic helical CT scan demonstrated hepatic vascular abnormalities, including arterioportal shunts, arteriosystemic shunts, telangiectasias, vascular masses, and parenchymal perfusion disorders, in up to 74% of 70 serial patients with HHT (125). Hepatic vascular abnormalities may be visualized with Doppler ultrasonography, CT angiography (Fig. 40.6), direct catheter angiography, or magnetic resonance angiography (126). Using contrastenhanced CT or catheter angiography as the gold standard, sensitive and specific sonographic criteria for HHT have been defined. These include a dilated common hepatic artery (>7 mm) and the presence of intrahepatic hypervascularization on Doppler evaluation (127). Therefore, absence of these findings on a sonographic study may obviate the need for additional imaging. Furthermore, screening for hepatic involvement in HHT is not generally required because most hepatic lesions remain asymptomatic and do not require treatment (125,128). There are several possible symptomatic presentations of HHT with hepatic involvement (Table 40.4). High-output cardiac failure presenting with dyspnea and edema may be related to extensive hepatic artery to hepatic vein shunting

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(129). Portal hypertension resulting from shunting between the hepatic artery and portal vein may present with ascites or variceal hemorrhage (129). Hepatic encephalopathy may develop in the presence of portal vein to hepatic vein shunting (130). Finally, cholestasis and biliary abnormalities may result from ischemic injury related to hepatic artery to hepatic vein shunting (129). Symptomatic disease can often be managed conservatively. Hepatic arterial embolization of vascular lesions was initially used with some success, but more recent reports have highlighted the high mortality rates associated with postembolization hepatic and biliary necrosis (131). Hepatic arterial embolization can no longer be recommended for the treatment of hepatic HHT. Liver transplantation has been successfully performed despite technical difficulties with vascular reorganization (132). However, a recent report suggests the possibility that in some patients vascular abnormalities may reoccur after transplantation (133).

▪ Figure 40.6 Contrast-enhanced computed tomography scan in a female patient with Rendu-Osler-Weber syndrome and hepatic involvement. In upper liver (A), heterogeneous hypervascularity of the liver parenchyma is shown. Hepatic veins are markedly dilated (black arrow). At the level of porta hepatis (B), the dilated tortuous proper hepatic artery is shown (black arrowheads).

Table 40.4. Hepatic Involvement of Hereditary Hemorrhagic Telangiectasia: Clinical Presentations

Clinical presentation

Type of shunting

High-output cardiac failure

Hepatic artery to hepatic vein

Dyspnea Edema

Portal hypertension Ascites

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Variceal bleeding

Hepatic encephalopathy

Portal vein to hepatic vein

Biliary abnormalities

Hepatic artery to hepatic vein

Cholestasis Cholangitis

P.1180

Peliosis Hepatis Peliosis hepatis is characterized by blood-filled cystic cavities in the hepatic parenchyma lined by hepatocytes or endothelial cells (134). Similar lesions may also develop in the spleen. Peliosis has been well described in immunosuppressed patients, including those with HIV infection, tuberculosis, and cancer, and after solid organ transplantation (135,136,137). Medications associated with peliosis hepatis include anabolic and androgenic steroids, azathioprine, and cyclosporine (136,138). Bartonella henselae, associated with cat-scratch disease, is the causative agent of bacillary peliosis hepatis in patients with HIV infection (135). Exposure to cat bites, scratches, and fleas are risk factors for acquisition of Bartonella henselae (135). This fastidious gram-negative bacillus has a granular and purple appearance on Warthin-Starry stain of affected hepatic specimens (134). Infection with the bacteria may also be demonstrated by blood culture, serologies, and polymerase chain reaction–based tests, although no single test is reliable. Some patients with bacillary peliosis hepatis also develop bacillary angiomatosis, characterized by vascular lesions affecting the skin (most commonly red or purple papules), lymph nodes, bones, and central nervous system. Imaging reports of peliosis hepatis are largely limited to isolated case reports (139,140,141,142). On sonography, vague areas of slightly decreased heterogeneous echotexture have been described. On unenhanced CT scan, irregular areas of low attenuation are shown. On MRI, lesions are usually of lowsignal intensity on T1-weighted imaging and high-signal intensity on T2-weighted imaging. However, appearance on MRI may vary if lesions are complicated by hemorrhage, with variable T1 brightening. On both CT and MRI, dynamic contrast enhancement demonstrates an early central enhancement, with gradual centripetal fill-in. This pattern is distinct from that of other vascular liver lesions, including hemangioma, adenoma, and focal nodular hyperplasia and may be the key to diagnosis. Peliosis hepatis is often an incidental finding. Among patients with HIV infection, fever, lymphadenopathy, anemia, elevated alkaline phosphatase level, and lower CD4 counts are more common in affected patients than in controls (143). Treatment of bacillary peliosis hepatis consists of several months of

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administration of erythromycin (500 mg four times daily) or an alternative macrolide. Nonbacillary peliosis is best treated by stopping the offending medication or addressing the underlying etiology. Performance of liver transplantation for treatment of severe peliosis hepatis has been reported (144).

Summary Budd-Chiari syndrome is an uncommon disease associated with thrombotic obstruction of the terminal hepatic venules, hepatic veins, vena cava, and/or right atrium. Sinusoidal congestion and centrilobular necrosis occur as a consequence of venous outflow obstruction and can lead to fibrosis and cirrhosis. Most patients present with chronic signs and symptoms of portal hypertension, although some may present subacutely or even acutely. Doppler sonography is an excellent screening test for evaluating the patency of the major hepatic veins and vena cava. CT scan and MRI are complementary studies. Venography remains the standard of reference for the diagnosis of venous occlusion and may either show the classic “spider web” appearance of hepatic vein obstruction or demonstrate intrahepatic or subcapsular collaterals. Liver biopsy and pressure measurements made during venography may also guide treatment selection. Rigorous studies are not available to derive definitive treatment algorithms. Generally, anticoagulation is offered to all patients. Diuretics and low-sodium diets are prescribed for those with ascites. If symptoms and hepatic synthetic function do not resolve after medical therapy, then decompressive procedures are offered. Some investigators recommend performance of surgical shunting or TIPS early in the course of disease. Thrombolytic therapy may be useful for fresh thrombosis. Angioplasty with or without stenting may treat focal stenoses. TIPS can effectively decompress hepatic sinusoids with symptomatic improvement. Surgical shunting has been used successfully for those with adequate hepatic reserve, although perioperative mortality can be high. Liver transplantation is preferred for patients with acute liver failure or decompensated cirrhosis. Survival after transplantation is similar to that of patients undergoing transplantation for nonmalignant cirrhosis of other causes. P.1181 HHT is characterized by epistaxis, mucocutaneous telangiectasias, and visceral arteriovenous malformations. Whereas liver transplant has been demonstrated frequently, patients with hepatic lesions are generally asymptomatic. Possible symptoms can include high-output cardiac failure, complications of portal hypertension, hepatic encephalopathy, and symptoms related to cholestasis. Management is most often conservative, and hepatic arterial embolization has been associated with unacceptably high mortality. Peliosis hepatis is often an incidental finding. Characteristic blood-filled cystic cavities may occur in the setting of immunosuppression or HIV infection. Bartonella henselae is the cause of bacillary peliosis hepatis in patients with HIV infection. Generally, treatment consists of addressing the underlying cause of immunosuppression or treating Bartonella infection.

Annotated References Denniger MH, Chait Y, Casadevall N, et al. Cause of portal or hepatic venous thrombosis in adults: the role of multiple concurrent factors. Hepatology 2000;31:587–591.

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The authors suggest that the occurrence of multiple prothrombotic disorders is more common than expected. Evaluation for hypercoagualable states in patients with hepatic or portal venous occlusion is recommended. Garcia-Tsao G, Korzenik JR, Young L, et al. Liver disease in patients with hereditary hemorrhagic telangiectasia. N Engl J Med 2000; 343:931–936. The authors describe and categorize symptomatic presentations in 19 patients with hereditary hemorrhagic telangiectasia involving the liver. Janssen HL, Garcia-Pagan JC, Elias E, et al. European Group for the Study of Vascular Disorders of the Liver. Budd-Chiari syndrome: a review by an expert panel. J Hepatol 2003; 38:364–371. The authors discuss difficulties with nomenclature. They emphasize that in the absence of rigorous studies, aggressive early treatment can not currently be advised. Klein AS, Molmenti EP. Surgical treatment of Budd-Chiari syndrome. Liver Transpl 2003; 9:891–896. This is a comprehensive review of surgical decompressive techniques. Patient selection and success with various procedures are discussed. Koehler JE, Sanchez MA, Garrido CS, et al. Molecular epidemiology of Bartonella infections in patients with bacillary angiomatosis-peliosis. N Engl J Med 1997; 337:1876–1883. This case–control study used molecular techniques to show that bacillary peliosis hepatis is associated exclusively with Bartonella henselae. Epidemiologic links to cat and flea exposures were identified. Menon KV, Shah V, Kamath PS. The Budd-Chiari syndrome. N Engl J Med 2004; 350:578–585. This is an informative, well-written review of all aspects of Budd-Chiari syndrome. Murad SD, Valla DC, de Groen PC, et al. Determinants of survival and the effect of portosystemic shunting in patients with Budd-Chiari syndrome. Hepatology 2004; 39:500–508. The authors present a large retrospective series of patients with Budd-Chiari syndrome (n = 237). On multivariate analysis encephalopathy, ascites, prothrombin time, and bilirubin were the only independent predictors of survival. Portosystemic shunting showed a trend towards improved survival in a select group of patients. Okuda K. Inferior vena cava thrombosis at its hepatic portion (obliterative hepatocavopathy). Semin Liver Dis 2002; 22:15–16. Okuda proposes that inferior vena cava obstruction, characterized by webs and membranes, and typically seen in Nepal, South Africa, China, India, and Japan,

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should be considered a distinct disease from classic Budd-Chiari syndrome. He proposes a new term, obliterative hepatocavopathy.

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136. Izumi S, Nishiuchi M, Kameda Y, et al. Laparoscopic study of peliosis hepatis and nodular transformation of the liver before and after renal transplantation: natural history and etiology in follow-up cases. J Hepatol 1994;20:129–137.

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Editors: Title:



Copyright ©2007 Lippincott Williams & Wilkins > Table of Contents > Volume 2 > Section VIII - Vascular Diseases of the Liver > Chapter 41 - The Liver in Circulatory Failure

Chapter 41 The Liver in Circulatory Failure Mitchell L. Shiffman

Key Concepts z

A dual blood supply protects the liver from developing ischemic injury during periods of systemic hypotension. When ischemia does occur it is typically limited to zone 3 of the hepatic lobule and resolves rapidly and spontaneously when systemic blood pressure is restored.

z

Ischemic hepatitis occurs in the setting of acute and severe hypotension and is associated with an abrupt and profound elevation in the levels of serum liver transaminases, which return to the normal range within several days. The serum bilirubin level rises and peaks 3 to 5 days after the peak in serum liver transaminase levels.

z

Occlusion of the hepatic artery or one of its branches will lead to infarction of the area supplied by the occluded vessel. Large hepatic infarcts may become infected and develop into a hepatic abscess.

z

The hepatic artery provides the only blood supply to the biliary ductal system. Injury to or occlusion of hepatic arterial branches may cause ischemic cholangiopathy. This results in stricture formation of bile ducts, which is often associated with dilatation proximal to the stricture.

z

Passive hepatic congestion may develop as a consequence of right ventricular failure and elevated central venous pressure. Ascites may develop from passive hepatic congestion in the absence of cirrhosis. Cardiac cirrhosis may develop after a prolonged period of passive hepatic congestion.

z

Passive hepatic congestion alone is only rarely associated with hepatic synthetic dysfunction even when cardiac ascites or cardiac cirrhosis is present. Liver dysfunction in this setting is most commonly the result of biventricular failure in which periods of hypotension and hepatic ischemia are superimposed on chronic hepatic congestion.

The liver has a dual blood supply and receives blood from both the hepatic artery and portal vein. These blood supplies mix within hepatic sinusoids and subsequently drain through multiple hepatic veins (1). Blood flow through the liver is therefore somewhat protected from the acute and chronic changes in cardiac output and systemic blood pressure. However, severe acute and/or prolonged changes in cardiac function may lead to hepatic dysfunction (2). Furthermore, the type of cardiac dysfunction may affect the liver in different ways. For example, cardiovascular failure associated with hypotension could

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affect hepatic arterial blood flow and oxygen delivery to the liver (3). If abrupt, severe, and self-limited, this could lead to a marked elevation in levels of liver aminotransferases (ATs) without affecting hepatic function and without long-term sequela. If less severe but chronic, only minor elevations in liver AT levels may occur but progressive fibrosis secondary to chronic hepatic ischemia may result. In contrast, cardiac dysfunction secondary to right ventricular failure may lead to an elevation in hepatic venous pressure, passive hepatic congestion, and P.1186 the development of ascites with or without cirrhosis (4). Hepatic injury caused by acute or chronic circulatory failure may therefore present with a wide spectrum of biochemical, histologic, and pathophysiologic patterns. This chapter focuses on liver injury caused by acute or chronic cardiac disease secondary to left ventricular dysfunction, right ventricular failure, valvular heart disease, constrictive pericarditis, congenital heart disorders, or circulatory failure secondary to heatstroke. Disorders of the liver that result from cardiac dysfunction include passive hepatic congestion, ischemic hepatitis, ischemic cholangiopathy, and hepatic infarction. The liver may also be injured or liver chemistries may become abnormal by many other disorders that affect hepatic blood flow. These disorders, which include hepatic vein thrombosis (see Chapter 40), portal vein thrombosis (see Chapter 40), hepatic veno-occlusive disease (see Chapter 40), sepsis (see Chapter 50), and various forms of immunologic disorders associated with vasculitis (see Chapter 11), will not be discussed in this chapter.

Anatomy and Physiology of Hepatic Blood Flow A detailed description of hepatic anatomy and the physiology of hepatic blood flow is provided in Chapter 7. This is only briefly reviewed here, with special emphasis on the pathophysiologic factors associated with circulatory failure. The liver has a rich blood supply derived from two sources (1). Two thirds of the total hepatic blood flow enters the liver through the portal vein. Portal blood contains large amounts of nutrients absorbed from the intestine, particularly after a meal, including glucose, amino acids, water-soluble vitamins, and triglycerides, but a relatively low oxygen tension. The remaining one third of hepatic blood flow is supplied by the hepatic artery. Hepatic arterial blood contains little nutrients but is rich in oxygen. More than half of the oxygen delivered to the liver originates from the hepatic artery, which is also the only blood supply for both the extrahepatic and intrahepatic biliary ductal systems. As a result, the liver and, particularly, the biliary ductal system are more susceptible to ischemic damage after an abrupt reduction in hepatic arterial blood flow than portal blood flow. In animal studies, ligation of the hepatic artery was associated with massive hepatic necrosis and death, whereas ligation of the portal vein was not (5). Inadvertent ligation of hepatic arterial branches during laparoscopic cholecystectomy (6) or purposeful embolization of hepatic arterial branches for treatment of hepatocellular carcinoma (HCC) (7) may lead to hepatic infarction of the segment supplied by the occluded vessel. Hypotension may also result in subsegmental, segmental, or global hepatic infarction (8). Patients with portal vein thrombosis, in which the only hepatic blood supply is through the hepatic artery, are particularly susceptible to hepatic failure secondary to a disruption in hepatic arterial blood flow. This may occur after chemoembolization of HCC or simply with hypotension. The functional unit of the liver is the hepatic acinus or lobule. This is a roughly

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pentagonal-shaped structure with a single central hepatic vein bound by five portal tracts (Fig. 41.1). Each portal triad contains a branch of the hepatic artery, portal vein, and a bile duct. Sheets of hepatocytes, one to two layers in thickness and lined P.1187 by hepatic sinusoids, stretch between the portal triads and central vein. Both portal and hepatic arterial blood enter the liver lobule through portal tracts, zone 1 of the hepatic acinus in the Rappaport classification (9). Blood from both of these sources then enters and mixes within hepatic sinusoids, flows to the center of the hepatic lobule (Rappaport zone 3), and exits the liver through a branch of the hepatic vein. As a result, zone 1 of the hepatic acinus contains oxygen- and nutrient-rich blood, and as this flows through the sinusoids, it is gradually depleted of both nutrients and oxygen. Zone 3 contains the smallest amount of nutrients and oxygen and is therefore the most susceptible to ischemic injury.

▪ Figure 41.1 A: Schematic drawing of a section of liver. The functional subunit of the liver is the hepatic lobule or acinus, a roughly pentagonalshaped structure with a central vein in the center and portal triads at each corner. Each portal triad is shared by several hepatic lobules. B: Schematic drawing of a hepatic lobule or acinus. Each portal triad contains a branch of the hepatic artery, portal vein, and bile duct. Sheets of hepatocytes extend between the central vein and portal triads at the edges of the lobule. Hepatic arterial and portal venous blood enters the acinus through the portal triad mix and then flow through hepatic sinusoids to the central vein. Zone 1 of the lobule lies at the periphery of the hepatic acinus (outer dashed circle). Zone 3 of the lobule lies in the center of the acinus (inner dashed circle).

Blood flow into the hepatic lobule is self-regulated by the hepatic microvasculature. Blood entering the liver through the low-pressure portal vein is slow, constant, only marginally affected by system blood pressure, and unregulated. In contrast, high-pressure hepatic arterial flow is tightly regulated so that total blood flow, the sum of portal and arterial blood flow, entering the liver lobule remains within a relatively narrow range (10). The buffering response of hepatic arterial blood flow to changes in portal blood flow is regulated by adenosine, a potent vasodilator of arterial smooth muscle cells (11,12). Adenosine is continuously secreted into the portal triad, and its local

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concentration is controlled by the blood entering the hepatic lobule. Therefore, as portal blood flow increases, the local adenosine concentration is diluted, hepatic arterioles constrict, and arterial blood flow declines. Alternatively, as portal blood flow declines, the local concentration of adenosine increases, hepatic arterioles dilate, and arterial blood flow increases. The response of hepatic arterial smooth muscle to adenosine is maintained in patients with cirrhosis (13). Infusion of adenosine has been shown to reduce hepatic ischemic injury in experimental animals (14,15) and reduce ischemic injury following reperfusion after liver transplantation (16). Adenosine appears to act locally by the synthesis of nitric oxide (17,18).

Ischemic Hepatitis Ischemic hepatitis refers to the disorders that cause liver injury by reducing oxygen delivery to the liver (19). This is most commonly seen in the setting of severe hypotension and global hepatic hypoperfusion (Table 41.1). In many patients ischemic hepatitis results from a severe acute decline in cardiac output associated with myocardial infarction, pulmonary embolus, or congestive heart failure. In other patients ischemic hepatitis may result from hypovolemia associated with massive hemorrhage, dehydration and heatstroke (20), sepsis, or hypoxia associated with acute respiratory failure. When associated with severe hypotension and shock, the term shock liver is frequently utilized.

Table 41.1. Causes of Ischemic Hepatitis

HYPOTENSION Cardiac dysfunction Right of left ventricular myocardial infarction Cor pulmonale Pulmonary embolus Acute exacerbation of congestive heart failure Hypovolemia Hemorrhage with or without preceding trauma Dehydration Burns associated with severe dehydration Miscellaneous causes Sepsis Heatstroke Sickle cell crisis HYPOXIA Acute respiratory failure or acute exacerbation of chronic respiratory disease Obstructive sleep apnea

Pathophysiology Ischemic hepatitis is not a true hepatitis because inflammation is uniformly absent on histologic examination. Rather, the hallmark of this disorder is zone 3 hepatic necrosis along with variable degrees of hepatic lobular collapse, depending on the duration and severity of the insult (Fig. 41.2). Fibrosis is characteristically absent unless there is a separate preexisting underlying chronic

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liver disorder or a long-standing circulatory disease associated with passive congestion, hypovolemia, or hypoxia. In patients with right ventricular infarction, changes associated with both acute passive congestion (see subsequent text) and ischemic hepatitis may be present. The histologic features of ischemic hepatitis resolve spontaneously, hepatocytes regenerate, and liver histology returns to normal in most patients. In patients with preexisting fibrosis and/or other histologic features of a chronic liver disorder, these changes either remain or recur after resolution of ischemic hepatitis.

Clinical Features and Outcome The clinical hallmark of ischemic hepatitis consists of an abrupt elevation in the levels of serum liver ATs, aspartate aminotransferase (AST) and alanine aminotransferase (ALT), and lactate dehydrogenase (LDH), which peak within 1 to 3 days of an episode of severe hypotension (Fig. 41.3). This is readily detected because patients with ischemic hepatitis typically are acutely ill and hospitalized, and undergo frequent biochemical testing of their renal, liver, and cardiac function. The peak in AT levels is typically in the 500 to 1,500 IU/L range, and these values return to normal within another 3 to 7 days as long as the hypotensive event is effectively treated and/or resolves (3,21,22,23). P.1188 The serum bilirubin level begins to rise 1 to 2 days after the elevation in serum AST and ALT levels and peaks 3 to 5 days after the maximum rise in liver AT levels. The maximal value for serum bilirubin observed in patients with ischemic hepatitis will vary greatly and depend on the inciting event and the presence of any underlying chronic liver disorder. Serum alkaline phosphate value may remain in the normal range or increase by only mild to moderate amounts. The international normalized ratio (INR) usually remains within normal limits. However, in particularly severe cases of ischemic hepatitis the patient may develop a mild prolongation in INR that rapidly corrects after administration of vitamin K. Changes in mental status are common in patients with ischemic hepatitis. However, this is usually secondary to cerebral hypoperfusion and hypoxia associated with the acute cardiocirculatory process. True hepatic encephalopathy associated with an elevation in serum ammonia level is distinctly rare.

▪ Figure 41.2 Histology of ischemic hepatitis. There is necrosis and

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ballooning degeneration of hepatocytes adjacent to the central vein, zone 3 of the hepatic lobule, with preservation of hepatocytes in zone 1 and portal structures.

▪ Figure 41.3 Pattern of serum alanine aminotransferase (ALT) and bilirubin level variation in patients with ischemic hepatitis. There is an abrupt and marked rise in serum aspartate aminotransferase (AST—not shown) and ALT levels to values of 200 to 1,000 IU/L. This is followed by a delayed rise in serum bilirubin level, which usually reaches a maximum 3 to 5 days after the peak in serum AST and ALT levels.

The possibility that the abrupt rise in serum liver AT levels in a patient with presumed ischemic hepatitis may actually result from an acute viral or nonviral hepatitis should always be considered. However, this rapid rise and fall in AST and ALT levels is unusual in acute viral hepatitis in which the transaminase levels return to normal over weeks rather than days. In addition, acute viral or nonviral hepatitis is frequently symptomatic and is associated with nausea, vomiting, anorexia, malaise, and/or right upper quadrant discomfort (19,24). These symptoms are only rarely present in patients with ischemic hepatitis. Despite this, serologic studies to exclude viral hepatitis A, B, and C may need to be performed in some cases. Nonviral causes of acute hepatitis that could present with an abrupt marked elevation in the values serum liver ATs include Wilson disease and autoimmune hepatitis (25,26). In most cases these disorders can be excluded simply by evaluating the clinical presentation, although appropriate serologic testing may also rarely be required. Finally, ischemic hepatitis is frequently associated with signs or symptoms of hypoxic or hypotensive injury to another organ; the one most commonly affected is the kidney. Therefore, a parallel rise in serum creatinine level is frequently observed in patients with ischemic hepatitis (3,23). Although the inciting event is readily apparent in most patients with ischemic hepatitis, a transient or subclinical hypotensive event may occasionally trigger this process and lead to uncertainty in the diagnosis. This is particularly common in patients with chronic right or left ventricular failure associated with chronic

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hypotension and/or passive hepatic congestion in which the liver is quite sensitive to even minor changes in hepatic arterial blood flow (24,27,28). Ischemic hepatitis may also be difficult to recognize in patients with hypoxia secondary to exacerbations in chronic pulmonary disease or sleep apnea in the absence of hypotension (29). The severity and prognosis of ischemic hepatitis is primarily dependent on the outcome of the inciting cardiocirculatory event. If the cause for hypotension is rapidly corrected the hepatic event is self-limited and resolves promptly. In contrast, if hypotension is extremely severe and/or persists despite prolonged resuscitative efforts multiorgan failure and death is likely to ensue. Ischemic hepatitis may lead to fulminant hepatic failure and death, but this is uncommon and typically occurs only in the setting of chronic congestive heart failure associated with passive hepatic congestion or cardiac cirrhosis (27) or in patients with cirrhosis from another form of chronic liver disease. The later situation is most frequently P.1189 encountered when a patient with cirrhosis develops hypotension secondary to massive variceal hemorrhage and/or sepsis. Ischemic hepatitis in patients with cirrhosis is associated with a mortality in excess of 60% (30,31).

Treatment The treatment of ischemic hepatitis is directed at restoring normal circulatory hemodynamics and correcting the cause of the hypotensive event. No specific therapy for enhancing hepatic recovery from ischemic hepatitis currently exists. One study has suggested that intravenous low-dose dopamine may augment hepatic blood flow but the benefit of this on hepatic recovery from ischemic hepatitis has not been demonstrated (32). Adenosine has been utilized in animal models but not in humans except to reduce reperfusion injury in donor liver grafts (14,15,16).

Hepatic Infarction Hepatic infarction represents the most severe form of ischemic hepatitis. Whereas ischemic hepatitis is associated with a global decline in hepatic blood flow and/or oxygen delivery secondary to a cardiocirculatory or other systemic process and is typically reversible, hepatic infarction occurs when blood flow to the liver, a particular lobe, segment, or subsegment, is interrupted secondary to occlusion of the hepatic artery or one of its branches. The involved segment of liver has no ability to recover and heals through the process of scar formation (33). Fortunately, only a branch or sub-branch of the hepatic artery is typically involved and the amount of liver rendered ischemic is limited to a segment or subsegment. In these cases, global hepatic function is only marginally impaired. However, if a major branch of the hepatic artery is occluded and the amount of liver rendered anoxic is too large the patient may develop acute liver failure and die without emergent liver transplantation. The various etiologies of hepatic infarction are listed in Table 41.2. Hepatic infarction may occur when the artery is injured during liver transplantation (34,35), cholecystectomy, (6,36) placement of a transjugular intrahepatic portosystemic shunt (TIPS) (37), administration of intra-arterial chemotherapy or purposeful embolization of the artery for treatment of HCC or cancer metastasis to the liver (7,38). Hepatic infarction may also result from a hypercoagulable state associated with vasculitis or polyarteritis (39,40,41,42,43), septic emboli

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(44), sickle cell crisis (45,46), polycythemia vera (33), and the use of oral contraceptives (47) and is seen in patients with toxemia of pregnancy (48,49). Severe arteriolar vasospasm associated with cocaine use may also lead to hepatic infarction (50,51).

Table 41.2. Causes of Hepatic Infarction

IATROGENIC ARTERIAL INJURY Liver transplantation Laparoscopic or open cholecystectomy Intra-arterial chemoembolization or chemoinfusion Placement of transjugular intrahepatic portosystemic shunt SYSTEMIC DISORDERS Polyarteritis Systemic lupus erythematosus Sickle cell crisis Emboli from infectious endocarditis HYPERCOAGULABLE STATES Abnormalities in coagulation system Polycythemia vera MISCELLANEOUS CAUSES Aortic dissection Toxemia of pregnancy Cocaine intoxication

Pathophysiology Hepatic infarction represents the most extreme form of ischemic injury to the liver, in which complete occlusion of the arterial supply renders the involved segment anoxic. Histologically there is complete coagulative necrosis of the entire hepatic acinus including all hepatocytes and portal structures that lie within the center of the involved segment. This is surrounded by a zone of inflammatory reaction. The periphery of the involved segment contains a zone of partial necrosis that closely resembles that seen in ischemic hepatitis, necrosis within zone 3 of the hepatic lobule with preservation of zone 1 structures (36). This area likely receives partial blood flow from an adjacent segment and will recover both histologically and functionally.

Clinical Features and Outcome Patients who develop hepatic infarction may be asymptomatic if the occlusion occurs during a surgical or invasive procedure. In such cases the hepatic infarction may be suspected when liver AT levels are found to be markedly elevated after the procedure. In other cases, particularly if liver chemistries are not monitored and the infarction is of limited size, the diagnosis may be missed and the infarction will only be identified incidentally if and when an imaging study is performed. In nonsurgical settings patients may experience right upper quadrant pain of variable intensity that radiates to the back or right shoulder and is associated with fever, nausea, and vomiting (36). P.1190 Leukocytosis is common and there is a dramatic rise in serum liver AT levels

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similar to what is observed in ischemic hepatitis. The serum bilirubin level may or may not rise depending on the size of the infarcted area. If a major branch of the hepatic artery is involved a large proportion of the liver will become infarcted and liver failure may occur (52). The diagnosis of hepatic infarction is confirmed with radiographic studies (53,54,55,56). If recognized acutely, ultrasound may demonstrate a focal hypoechoic area, and if the occlusion is of a large hepatic artery, Doppler flow ultrasonography may demonstrate the absence of flow in the involved vessel. Ultrasound is unlikely to detect the absence of flow in a smaller subsegmental branch of the hepatic artery. Abdominal computed tomography (CT) scan demonstrates a segmental area of low attenuation. The lesion may be wedge shaped and extend outward to the periphery of the liver (Fig. 41.4). Round or oval infarcted lesions are usually located within the center of the liver, or the lesion may be irregular and follow the course of the intrahepatic vasculature and biliary tracts (53,54). In such cases, marked biliary dilatation in the involved area occurs as the lesion heals (Fig. 41.5). With magnetic resonance (MR) imaging the lesion has diminished T1 and increased T2 signal intensity. MR angiography may also demonstrate the area of occlusion if a sufficiently large branch of the hepatic artery is involved (56,57). It is rarely necessary to perform biopsy in an area of hepatic infarction. The diagnosis is based on the clinical history and radiographic findings. There is frequently a history of gallbladder, biliary tract, or hepatic surgery; a recent angiographic infusion to the involved area; a known hypercoagulable state; or another associated event (Table 41.2). In cases in which the diagnosis is uncertain and the lesion is radiographically atypical in its appearance, an ultrasound-directed biopsy may be useful. The major short-term concern is that the infarcted area will become infected and develop into an hepatic abscess. This is most commonly encountered after embolization of a hepatic tumor (38,58,59). In cases in which abscess formation is suspected broad-spectrum antibiotics should be initiated and needle aspiration of the lesion performed.

▪ Figure 41.4 Computed tomography scan of a patient with a segmental

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hepatic infarct. Note the wedge-shaped region of infarction that extends from the center of the liver to the periphery and the liver capsule.

▪ Figure 41.5 Magnetic resonance image of a patient who developed an hepatic infarction and ischemic cholangiopathy after an episode of severe acute cholecystitis and cholecystectomy. Note that the area of infarction follows the course of the biliary tree and is associated with dilatation of bile ducts. Hepatic arteriogram (not depicted) demonstrated occlusion of intrahepatic branches of the left and middle hepatic artery corresponding to the area of infarction and cholangiopathy.

Treatment No specific treatment for hepatic infarction is required. However, if the infarcted area is large the likelihood for abscess formation is increased and such patients should be closely monitored for signs of sepsis and/or treated with empiric antibiotics (58,59). Abscess formation is extremely common in patients who develop hepatic infarction after liver transplantation and is the major reason why such individuals undergo emergent retransplantation (34,35). Patients with massive hepatic infarction and liver failure should be considered candidates for emergent liver transplantation. Finally, if the cause for the infarction is not readily apparent a diagnostic evaluation for a source of emboli or an underlying hypercoagulable state is warranted.

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P.1191

Ischemic Cholangiopathy The bile ducts receive their blood supply exclusively from branches of the hepatic artery and are therefore more sensitive to alterations in hepatic arterial flow than is the liver parenchyma, which also has a portal blood supply (1). Hepatic arterial injury or occlusion associated with hepatic infarction or profound hypotension associated with ischemic hepatitis frequently causes injury to the biliary ductal system. However, ischemic cholangiopathy may also occur in the absence of hepatic ischemia. Ischemic bile duct injury is most commonly observed after cholecystectomy, biliary tract surgery, hepatectomy, and liver transplantation but may also be caused by any of the etiologies listed in Table 41.2 (60,61,62,63,64). Ischemic injury to the bile ducts results in the development of biliary strictures. This is commonly accompanied by dilatation of the biliary tree proximal to the lesion. Typically there is only a single focal stricture. However, in some cases the stricture may be quite long or there may be multiple strictures with intervening dilatation. In some cases these strictures may resemble those seen in cholangiocarcinoma or primary sclerosing cholangitis (PSC). However, most ischemic bile duct strictures have a smooth symmetric appearance and are confined to a focal segment of the liver. This is unlike that seen in patients with PSC, in which the strictures tend to be located throughout the liver. The development of an ischemic biliary stricture may be asymptomatic and only recognized when imaging studies are performed to evaluate the liver for an elevation in alkaline phosphatase level. The serum bilirubin level is usually normal. However, a mild to moderate elevation in serum bilirubin level or jaundice may develop if the stricture totally occludes the bile duct or is located in a major large bile duct. Patients in whom ischemic cholangiopathy is suspected should undergo extensive imaging of the biliary ductal system with either an MR or endoscopic cholangiogram and serologic testing to exclude PSC (see Chapter 23) and/or cholangiocarcinoma (see Chapter 4). Placement of an endoscopic biliary stent or surgical revision of the bile duct is indicated if the bilirubin level is elevated. In an asymptomatic patient, liver biopsy of the involved lobe proximal to the stricture is frequently useful because this can identify histologic changes consistent with bile duct obstruction and patients at risk for developing secondary biliary cirrhosis. Intrahepatic bile duct dilatation and duplication proximal to the stricture has been identified histologically (65). Placement of an endoscopic stent should probably be performed in such patients, although no data currently exists to demonstrate that this reduces the risk for developing biliary cirrhosis. One study in a group of pediatric liver transplant recipients has suggested that the use of ursodeoxycholic acid in addition to stenting may prevent secondary biliary cirrhosis (62). In the liver transplant recipient, hepatic artery thrombosis in the immediate post-transplantation period is associated with extensive stricture formation of the biliary tree, intrahepatic abscess formation, and graft failure and is therefore an indication for emergent retransplantation (34,63). The development of biliary strictures months to years after liver transplantation is best treated endoscopically as in the nontransplantation setting.

Heatstroke and the Liver Heatstroke is a severe systemic and potentially fatal disorder with a mortality

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rate approaching 25% (20,66,67). The syndrome is characterized by hyperexia (a body temperature above 41°C), profound hypotension, neurologic impairment, heat-induced tissue injury, sepsis, disseminated intravascular coagulation, and multiorgan failure. The liver is frequently injured by heatstroke; excessive body temperature itself causes hepatic necrosis, and severe hypotension is associated with a superimposed ischemic hepatitis. Serum AT and LDH levels are markedly elevated in patients with heatstroke. However, the elevation in AST level is frequently much greater than the elevation in ALT level because of thermal injury to muscles, the brain, and kidneys (20,66,67). The elevation in serum ALT level is rarely greater than 20 times the upper limit of normal, and bilirubin level frequently remains normal or is only mildly elevated. The peak in serum AT levels, like that observed in ischemic hepatitis, occurs 1 to 2 days after the event. However, as opposed to ischemic hepatitis, serum levels of liver ATs recover much more slowly—over weeks rather than days (20). Elevations in serum ALT levels to values greater than this and/or a progressive rise in serum bilirubin level is associated with high mortality. The histologic changes observed in patients with heatstroke consist of zone 3 necrosis, similar to that observed in patients with ischemic hepatitis. However, steatosis, dilatation of hepatic and portal veins, sinusoidal dilatation, and cholangiolar proliferation are also observed (68,69,70). These changes resolve spontaneously and liver histology returns to normal without the development of fibrosis in patients who recover from this insult.

Passive Hepatic Congestion Passive hepatic congestion occurs in patients with isolated right-sided heart failure or cardiopulmonary P.1192 disease associated with a persistent elevation in right atrial pressure (2,4,71). This may include biventricular heart failure secondary to alcoholic or ischemic dilated cardiomyopathy, isolated right coronary artery occlusion and right ventricular myocardial infarction, severe pulmonary hypertension, cor pulmonale, mitral stenosis, and various forms of congenital heart disease. Passive hepatic congestion may also develop in patients with hypertensive restrictive cardiomyopathy and end-stage renal failure. All patients with passive hepatic congestion have elevated central venous pressure, which is transmitted backwards through the hepatic veins, to the central veins of the hepatic acinus, and into the sinusoids of the hepatic lobule. Chronic liver injury resulting from this process is referred to as congestive hepatopathy. Over time this process may lead to cardiac fibrosis or cardiac cirrhosis.

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▪ Figure 41.6 Gross appearance of the cut surface of the liver in a patient with passive hepatic congestion. The characteristic appearance is of a “nutmeg” liver, small reddish areas surrounded by paler areas.

Pathophysiology Evidence of congestive hepatopathy can be seen on gross pathologic examination of the liver. The liver is enlarged and appears congested and purplish with prominent hepatic veins. The cut surface of the liver reveals the classic description of “nutmeg liver” (Fig. 41.6); reddish central areas correspond to central vein congestion and hemorrhage into zone 3 of the hepatic lobule, surrounded by pale or yellowish areas representing zones 1 and 2 that are either histologically normal or contain fatty change. Microscopic examination reveals prominent central veins, central vein hemorrhage, dilated sinusoids, and hemorrhagic necrosis within zone 3 (2,72). Variable degrees of fibrosis may be seen circumscribing central veins (Fig. 41.7). Over time bridging fibrosis may extend between central veins, and this will eventually progress to form cirrhotic nodules. Histologically, this form of cirrhosis is unique compared to that resulting from all other forms of chronic liver disease in which portal-to-portal fibrosis occurs. In some cases, regeneration of periportal hepatocytes within zone 1 may yield discrete nodules lacking surrounding fibrosis. Such nodules do not represent cirrhosis and are referred to as regenerative nodular hyperplasia (see Chapter 42). Chronic passive congestion of the hepatic lobule leads to a series of pathophysiologic alterations that causes cardiac cirrhosis and ascites formation and that renders zone 3 hepatocytes more susceptible to ischemic injury (72). When exposed to high pressure, as occurs with passive congestion, sinusoidal fenestrae enlarge and this allows large amounts of protein-rich fluid to enter the space of Disse (1). Accumulation of fluid within the space of Disse is typically drained by hepatic lymphatics. But when the capacity to drain hepatic lymph is P.1193 exceeded by the hemodynamic forces associated with passive congestion, high protein–containing fluid within the space of Disse leaks into the peritoneal cavity and produces high-protein ascites (Fig. 41.8) (4,73). Chronic passive congestion also leads to sinusoidal fibrosis that impairs the diffusion of nutrients and oxygen

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across the space of Disse and into zone 3 hepatocytes, and it is this process that appears to increase the susceptibility of zone 3 hepatocytes to hypoxic injury in patients with coexistent left ventricular cardiac dysfunction. There appears to be no correlation between the elevation in right atrial pressure and the severity of liver injury in patients with passive hepatic congestion (2). In addition, zone 3 necrosis is rarely, if ever, seen in patients with isolated right ventricular failure in the absence of left ventricular failure and hypotension (3,24,28). It is therefore apparent that although patients with passive hepatic congestion may develop progressive fibrosis, cirrhosis, and ascites, hepatic function in patients with passive congestion is generally well preserved and liver-related mortality is rare except in the setting of coexistent left ventricular failure, hypotension, and hepatic ischemia.

▪ Figure 41.7 Microscopic appearance of the liver with passive hepatic congestion. A: Congestion, dilatation, and hemorrhage at the central vein. B: Dilatation of sinusoids radiating outward from the central vein and sinusoidal fibrosis. C: Fibrosis of the central vein with extension of fibrosis radiating outward along hepatic sinusoids.

▪ Figure 41.8 Schematic drawing of the pathophysiologic mechanisms

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involved in the formation of ascites in patients with passive hepatic congestion. The normal hepatic sinusoid (top half) is lined with sinusoidal epithelium containing small fenestrae. In patients with passive hepatic congestion (lower half) the elevated hepatic venous pressure causes the sinusoidal epithelial fenestrae to increase in size. Large amounts of albumin and other plasma proteins enter the space of Disse, pass through hepatocyte junctions, and form ascites containing a high concentration of protein and a low serum to ascites albumin gradient (SAAG).

Clinical Features and Outcome Patients with passive hepatic congestion are typically identified in one of three ways: They are asymptomatic and are found to have mild abnormalities in serum liver chemistries, a mild elevation in total bilirubin, or a mild prolongation in the INR; they present with symptoms of hepatic congestion, usually a dull ache in the right upper quadrant; or they present for evaluation of ascites. At the time of presentation, patients may already be known to have right ventricular failure or the accompanying cardiac disease may not have been appreciated. Regardless of the presentation, physical findings of right ventricular failure and passive hepatic congestion can be found. The most common of these include jugular venous distension, hepatomegaly, and hepatojugular reflux. In patients with marked tricuspid insufficiency, presystolic pulsations may be felt through the liver (74). Lower extremity edema may be absent in patients with isolated right ventricular failure but is typically present in patients with biventricular failure. Laboratory studies may demonstrate mild elevations in the levels of serum liver AT, alkaline phosphatase, and bilirubin, although each of these chemistries may also be within the limits of normal. When an elevation in total bilirubin level is present, it is frequently the unconjugated fraction (4). In addition, the increase in serum bilirubin level appears to correlate with the severity of passive congestion and the elevation in right atrial pressure (2). In some patients with severe acute right ventricular failure and marked elevations in right atrial pressure the total bilirubin level may approach 20 mg/dL. Serum albumin level is typically normal or only slightly reduced. The most consistent abnormal laboratory value in patients with passive hepatic congestion is the INR, which is almost always prolonged to approximately 1.5. Serum ammonia level may be elevated in some patients but is only rarely associated with symptoms of hepatic encephalopathy (75). In patients with biventricular failure, episodes of hypoperfusion and hypoxia secondary to exacerbations of left ventricular failure may lead to more severe or abrupt abnormalities in serum liver chemistries. Echocardiography findings are frequently abnormal and may demonstrate right ventricular contraction defect, tricuspid insufficiency, and/or an elevation in pulmonary arterial pressure. Hepatic ultrasound demonstrates hepatomegaly and diffuse increased echogenicity throughout the liver. Reversal of flow in the hepatic veins may be seen with Doppler ultrasonography. Contrast-enhanced CT scan and MR imaging demonstrate a heterogeneous appearance of the liver parenchyma (76). This is consistent with the gross “nutmeg” appearance of the liver that results from intervening areas of central vein hemorrhage and preserved portal blood flow (Fig. 41.9). Enlargement of the hepatic veins may also be present.

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Ascites is a frequent finding in patients with passive hepatic congestion and this typically occurs in the absence of cirrhosis. The ascitic fluid contains a high concentration of protein, typically greater than 2.5 g/dL with a serum to ascites albumin gradient (SAAG) of less than 1.1 (77). When cardiac cirrhosis has developed from long-standing passive hepatic congestion, the SAAG usually remains below 1.1 but may approach or exceed this value, particularly in patients in whom a P.1194 coexistent underlying liver disorder has contributed to the development of cirrhosis. It is therefore helpful to assess liver histology in a patient with passive hepatic congestion, even in those with a low SAAG. Because it is difficult to perform percutaneous liver biopsy in most patients with ascites, a biopsy may need to be performed through the transjugular approach. In such patients, measuring hepatic venous pressure and calculating the hepatic venous pressure gradient (HVPG) is an excellent complementary way to help determine whether ascites is secondary to chronic passive congestion or is caused by a secondary liver disorder that has led to the development of cirrhosis. In patients with passive hepatic congestion both the free and wedged hepatic venous pressures are elevated and the HVPG is normal. This may also be true for patients with cardiac cirrhosis. In contrast, patients with passive congestion and cirrhosis, but who develop cirrhosis from another underlying chronic liver disease (i.e., chronic viral or nonviral hepatitis), will not only have an elevated free hepatic venous pressure but also an elevated HVPG.

▪ Figure 41.9 Magnetic resonance image of a patient with severe pulmonary hypertension, right ventricular failure, tricuspid regurgitation, and jugular venous distension. Note the mottled appearance of the liver parenchyma that corresponds histologically to centrilobular areas of passive congestion with intervening areas of preserved portal blood flow.

Patients with passive hepatic congestion typically have stable hepatic function for prolonged periods, even with the presence of ascites and even after they have developed cardiac cirrhosis (2). Esophageal varices are rarely present even in

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patients who have developed cardiac cirrhosis. The long-term mortality associated with passive hepatic congestion is therefore dictated by the mortality associated with the underlying cardiac disease; this is considerably reduced in patients with biventricular failure. Acute liver failure and liver-related mortality is only observed in those patients with biventricular failure in whom episodes of left ventricular failure lead to hypotension and a superimposed ischemic hepatitis (21,27,78).

Treatment The treatment for passive hepatic congestion is to improve forward cardiac output. This is associated with an improvement in serum liver chemistries and a reduction in ascites formation. Ascites should be treated with diuretics. However, excessive use of diuretics could lead to dehydration, hypotension, and hepatic ischemia (78). Paracentesis should not be performed repeatedly as a treatment for refractory ascites in patients with passive hepatic congestion because this leads to severe protein loss and accentuates protein malnutrition owing to the high protein content of the ascitic fluid. Placement of a TIPS is contraindicated in the treatment for refractory ascites in this setting (79). This stent would provide a direct communication between the high-pressure central venous system and the portal system, lead to a marked increase in portal hypertension, and may precipitate massive variceal hemorrhage. Placement of a peritoneal–venous shunt is also contraindicated. In the setting of cardiac failure the delivery of additional volume to the heart is likely to exacerbate the underlying cardiac disease. In addition, the high pressure within the jugular vein of these patients will typically prevent flow of ascites from the lower-pressure abdominal cavity. Finally, the protein content of the ascitic fluid in patients with passive congestion tends to occlude the peritoneal–venous shunt within a relatively short period. Several medications should be avoided or used with extreme caution in patients with passive hepatic congestion. These patients are extremely sensitive to warfarin (Coumadin); they have a baseline prolongation of INR, and this increases substantially when even very low doses of warfarin (Coumadin) are administered. Furthermore, acute exacerbations in cardiac failure will result in a marked prolongation in INR even in patients in whom this was previously well controlled. Patients with hepatic congestion also metabolize drugs more slowly. As a result, these patients are susceptible to toxicity from any drug that is metabolized by the liver and in cases in which an elevation in the blood level of the native drug may cause side effects.

Constrictive Pericarditis Constrictive pericarditis produces clinical and pathologic changes similar to those observed in the Budd-Chiari syndrome (see Chapter 40). Indeed, it has been suggested that the original patient described by Budd actually had constrictive pericarditis as opposed to hepatic vein thrombosis (80). Constrictive pericarditis is P.1195 associated with marked elevations in central venous pressure that are sufficient to cause both zone 3 hemorrhage and necrosis. Cirrhosis develops much more rapidly in patients with constrictive pericarditis than in other forms of passive congestion. The physical examination is characterized by marked jugular venous distension that arises during inspiration (Kussmaul's sign), a pericardial knock, massive hepatomegaly, massive ascites, and peripheral edema. Liver AT levels

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are variably elevated but jaundice is frequently absent (80,81). All signs and symptoms resolve after pericardiectomy.

Congenital Heart Disease Congenital heart disease represents a wide spectrum of cardiopulmonary abnormalities that most commonly become apparent shortly after birth or within the first few years of life. Both passive hepatic congestion and/or hepatic ischemia can be seen in these children, the severity of which is determined by the particular cardiac anomaly present. As in adults, children with biventricular failure and both passive hepatic congestion and a low cardiac output state associated with hypotension and intermittent ischemic hepatitis develop the most severe liver injury and have the highest mortality. This is most commonly observed in children with hypoplastic left ventricle, coarctation of the aorta, and transposition of the great vessels (82,83,84). Major advances in the surgical treatment of congenital heart disease have significantly reduced early mortality in these infants and children. As a result, many now reach adulthood and develop side effects related to long-standing passive hepatic congestion (85). Patients with passive hepatic congestion secondary to congenital heart disease present in a similar manner as other patients with this hepatic disorder. They are found to have abnormal liver chemistries or ascites. Their evaluation and management is likewise similar. However, many of these patients may also be found to have concomitant hepatitis C virus (HCV) infection from blood products they received at the time of cardiac surgery (86). In this situation, the underlying heart disease should not be considered an absolute contraindication for treatment of chronic HCV if indicated. As patients with congenital heart disease grow and reach adulthood, some may develop worsening heart failure and require cardiac transplantation (87). Passive congestion even with cardiac ascites should not be considered a contraindication to proceeding with cardiac transplantation as long as cirrhosis is absent. A complete evaluation of liver function, histology, and hemodynamics, to include the HVPG, should therefore be undertaken in patients with congenital heart disease who are being considered candidates for cardiac transplantation.

Annotated References Bianchi L, Ohnacker H, Beck K, et al. Liver damage in heatstroke and its regression. Hum Pathol 1972;3:237–248. Detailed description of how the liver is affected by heatstroke. Prognostic features of liver injury during heatstroke and factors associated with recovery from this are also discussed. Lautt WW. Mechanism and role of intrinsic regulation of hepatic arterial blood flow: hepatic arterial buffer response. Am J Physiol 1985;249:G549–G556. This study describes the mechanism by which hepatic blood flow is regulated. This involves the release of paracrine substances that affect portal venous and hepatic arterial blood flow into the liver. Sherlock S. The liver in heart failure: relation of anatomical, functional and circulatory changes. Br Heart J 1951;13:273–293.

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One of the first large series in which liver histology was correlated with the clinical findings of cardiovascular disease. Many of the classic features that describe the impact of heart failure on the liver were first noted in this case series. These features have not changed in over 50 years. Weinberg AG, Bolande RP. The liver in congenital heart disease. Am J Dis Child 1970;119:390–394. Case descriptions of how various congenital heart defects affected liver function.

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42. Haratake J, Horie A, Furuta A, et al. Massive hepatic infarction associated with polyarteritis nodosa. Acta Pathol Jpn 1988;38:89–93.

43. Millan-Mon A, Porto JL, Novo C, et al. Hepatic infarction in a pregnant patient with the ‘primary’ antiphospholipid syndrome. Lupus 1993;2:275–279.

44. Henrich WL, Huehnergarth J, Rosch J, et al. Gallbladder and liver infarction occurring as a complication of acute bacterial endocarditis. Gastroenterology 1975;68:1602–1607.

45. Betrosian A, Balla M, Kafiri G, et al. Case report: reversal of liver failure in sickle cell vasoocclusive crisis. Am J Med Sci 1996;311:292–295.

46. Gauthier N, Cornud F, Vissuzaine C. Liver infarction in sickle cell disease. AJR Am J Roentgenol 1985;144:1089–1090.

47. Jacobs MB. Hepatic infarction related to oral contraceptive use. Arch Intern Med 1984;144:642–643.

48. Zissin R, Yaffe D, Fejgin M, et al. Hepatic infarction in preeclampsia as part of the HELLP syndrome: CT appearance. Abdom Imaging 1999;24:594– 596.

49. Krueger KJ, Hoffman BJ, Lee WM. Hepatic infarction associated with eclampsia. Am J Gastroenterol 1990;85:588–592.

50. Bunn WH, Giannini AJ. Cardiovascular complications of cocaine abuse. Am

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51. Moen MD, Caliendo MJ, Marshall W, et al. Hepatic rupture in pregnancy associated with cocaine use. Obstet Gynecol 1993;82(Suppl):687–689.

52. Khoury G, Tobi M, Oren M, et al. Massive hepatic infarction in systemic lupus erythematosus. Dig Dis Sci 1990;35:1557–1560.

53. Wellings RM, Olliff SP, Olliff JF, et al. Duplex Doppler detection of hepatic artery thrombosis following liver transplantation. Clin Radiol 1993;47:180– 182.

54. Adler DD, Glazer GM, Silver TM. Computed tomography of liver infarction. AJR Am J Roentgenol 1984;142:315–318.

55. Hobert BL, Baron RL, Dodd GD. Hepatic infarction caused by arterial insufficiency: spectrum and evolution of CT findings. AJR Am J Roentgenol 1996;166:815–820.

56. Fields MS, Desai RK. Hepatic infarction: MRI appearance. Cleve Clin J Med 1991;58:353–355.

57. Tuvia J, Lebwohl O, Lefkowitz J. Hepatic infarction due to thrombotic angiitis; MR appearance. Clin Radiol 2000;55:803–805.

58. Gates J, Hartnell GG, Stuart KE, et al. Chemoembolization of hepatic neoplasms: safety, complications, and when to worry. Radiographics 1999;19:399–414.

59. Itai Y, Ohtomo K, Kokubo T, et al. CT and MR imaging of postnecrotic liver scars. J Comput Assist Tomogr 1988;12:971–975.

60. Schmidt SC, Langrehr JM, Hintze RE, et al. Long-term results and risk factors influencing outcome of major bile duct injuries following cholecystectomy. Br J Surg 2005;92:76–82.

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67. Hassanein T, Razack A, Gavaler J, et al. Heatstroke: its clinical and pathological presentation with particular attention to the liver. Am J Gastroenterol 1992;87:1382–1389.

68. Rubel LR, Ishak KG. The liver in fatal exertional heatstroke. Liver 1983;3:249–260.

69. Kew MC, Minick OT, Bahu RM, et al. Ultrastructural changes in the liver in heatstroke. Am J Pathol 1978;90:609–618.

70. Bianchi L, Ohnacker H, Beck K, et al. Liver damage in heatstroke and its regression. Hum Pathol 1972;3:237–248.

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Editors: Title:



Copyright ©2007 Lippincott Williams & Wilkins > Table of Contents > Volume 2 > Section IX - Benign and Malignant Tumors: Cystic Disorders > Chapter 42 - Benign Solid Tumors

Chapter 42 Benign Solid Tumors Arie Regev

Key Concepts z

Benign solid lesions of the liver are detected with increasing incidence due to the frequent use of imaging studies of the abdomen. They are usually found incidentally in patients with no liver disease.

z

Hemangioma of the liver is the second most common benign focal hepatic lesion (simple cyst being the most common one) and the most common solid hepatic tumor (1% to 7.4% of the normal population). It is rarely of significant clinical consequence.

z

Focal nodular hyperplasia (FNH) is less common than hemangioma (0.4% of the normal population) and only rarely poses any significant risk.

z

There is rarely an indication for a surgical intervention in patients with a hemangioma, FNH, or most other benign solid lesions.

z

In contrast to hemangioma and FNH, hepatic adenoma is a rare tumor (0.004% of the normal population), which may cause significant morbidity from bleeding, rupture, or malignant transformation, and usually requires surgical resection.

z

There is a strong association between hepatic adenoma and oral contraceptives (OCPs), and a history of prolonged use of OCPs should be sought in every woman with a focal hepatic lesion.

z

A strong relationship to OCPs has not been unequivocally shown for hemangioma or FNH, although this issue remains controversial.

z

A focal lesion in a patient with cirrhosis should not be regarded as benign and should be considered a malignancy until proved otherwise.

Benign focal lesions of the liver are found with increasing incidence because of the frequent use of imaging studies of the abdomen. They represent a relatively common reason for referral to the hepatologist or gastroenterologist. Most benign lesions are detected incidentally by imaging studies performed for unrelated reasons. Technical advances in imaging modalities have led to the identification of smaller lesions that until recently were not detected. Many of the lesions that present as a focal liver mass are true neoplasms, while others result from reactive proliferation of different cells. In general, benign tumors of the liver may arise from hepatocytes, bile duct epithelium, the supporting mesenchymal tissue, or a combination of two or more of these (Table 42.1). Although most patients with benign hepatic tumors are asymptomatic, a minority may present with symptoms that may be local or systemic. In these patients, the relationship between the symptoms and the hepatic lesions may be difficult to

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correlate, and additional workup is necessary to rule out other causes for the patients' complaints. In most cases patients with benign hepatic lesions have no preexisting liver disease, and the finding of a coexisting chronic liver disease such P.1202 as chronic hepatitis B, hemochromatosis, or cirrhosis should raise a suspicion for a malignant tumor. A conclusive diagnosis of a focal hepatic lesion is essential because it may represent a primary or secondary malignancy, which may require immediate treatment. In addition, some benign lesions carry specific risks such as rupture, bleeding, malignant transformation, consumptive coagulopathy, and disseminated intravascular coagulation. Focal solid hepatic lesions often represent a diagnostic challenge for the clinician and frequently mandate extensive evaluation. They may be difficult to characterize and at times impossible to differentiate from malignant tumors by the clinical presentation. Nevertheless, the importance of a detailed history and physical examination in the assessment of a patient with a newly discovered focal liver lesion cannot be overemphasized. Often the clinical presentation provides important clues to a specific diagnosis and suggests whether the tumor is benign or malignant. Still, in many cases the clinical information and the first imaging study are nondiagnostic and the clinician must choose additional studies from an ever-increasing number of available options. Despite continuing advancement in sensitivity and accuracy, imaging studies fail to yield conclusive diagnosis in a sizable number of patients, and in these cases histopathologic assessment is necessary to characterize the lesion. A tissue sample may be obtained by an ultrasonography or computed tomography (CT)-guided percutaneous liver biopsy or by a laparoscopic liver biopsy. Histopathologic evaluation remains essential in the clinical management of a significant number of tumors or masses in the liver; possible exceptions include hemangioma, focal nodular hyperplasia (FNH), and focal fatty change, which may be unequivocally diagnosed by imaging studies. Unfortunately, in some benign lesions (e.g., hemangioma and hepatic adenoma) liver biopsy carries a high risk of bleeding and is therefore contraindicated. A fundamental knowledge of the various lesions and their characteristic features should help in the differential diagnosis.

Table 42.1. Benign Solid Tumors of the Liver

EPITHELIAL TUMORS Hepatocellular adenoma Bile duct adenoma Biliary cystadenoma MESENCHYMAL TUMORS Hemangioma Infantile hemangioendothelioma Fibroma Angiomyolipoma Lipoma Lymphangioma Benign mesenchymoma MIXED TUMORS Teratoma TUMOR-LIKE LESIONS Focal nodular hyperplasia Nodular regenerative hyperplasia Mesenchymal hamartoma

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Microhamartoma (von Meyenburg complex) Inflammatory pseudotumor Focal fatty change Pseudolipoma Macroregenerative nodule

Focal Nodular Hyperplasia Epidemiology FNH is a benign tumor-like lesion of unclear etiology. It is the second most common benign solid mass of the liver (after hepatic hemangioma), and its incidence has been reported between 0.31% and 0.6% (1,2). It is diagnosed predominantly in adult women but has also been reported in men (female-to-male ratio of approximately 8:1) and children. In most cases, it is an incidental finding on abdominal imaging or surgery performed for unrelated reasons. FNH is solitary in most cases and is located in the right lobe more often than in the left (3). Two or more lesions are encountered in approximately 20% of the patients and a distinct minority may have more than five lesions (3,4,5). The size may range from 1 mm to more than 20 cm; however, most (64%) are smaller than 5 cm in diameter (3). Although many of the patients may have a history of oral contraceptive (OCP) use (6), the association of FNH with OCPs is controversial. Some authors have suggested increased prevalence and increase in size in women who use OCPs (7), but most studies found no relationship between estrogens and the size or number of FNH (8). Although these are two distinct lesions, there are rare reports of FNH coexisting with hepatic adenoma (9,10).

Pathogenesis FNH is considered to be hyperplastic rather than neoplastic in origin, although its exact pathogenesis remains a matter of controversy. It typically occurs in the background of a healthy liver. It is believed by many to be a hyperplastic response to a preexisting vascular anomaly in the location of the lesion. According to this theory, the initial injury may be arterial malformation, which leads to increased arterial blood flow to a specific region compared to the adjacent parenchyma, which in turn leads to high sinusoidal pressure, resulting in hepatocellular hyperperfusion. This may be followed by local angiogenesis, leading to hyperplasia and causing the typical arterial branching in the center of the FNH (1). A recent report of FNH diagnosed in the same hepatic segment in identical twins supports the theory of a congenital anomaly being an initial event in the P.1203 pathogenesis of this lesion, at least in some patients (11). Because of the female predominance, a link with OCPs has been postulated; however, this relationship remains debatable. Some studies and case reports have suggested that the development of the vascular malformation or the growth of the FNH may be influenced by estrogen; however, this has never been unequivocally proved

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(7,12,13). In contrast, other clinical studies have found no association between the use of OCP or pregnancy and FNH. One retrospective study found no such association in 216 women with FNH (8). Most FNHs are supplied by a single artery, which is typically enlarged. In contrast to the usual situation, this artery is not accompanied by a portal vein or a bile duct. In some cases, the FNH is predominantly supplied by the portal vein (13), which may result from thrombosis of the central artery in large lesions. Although some reports suggested that FNH may be a clonal lesion on the basis of a uniform pattern of X-chromosome inactivation (14,15), others have shown it to be of a clear polyclonal nature (16). Recently, several authors suggested a causal relationship between systemic cytotoxic chemotherapy (usually alkylating agents such as busulfan or melphalan) and subsequent development of FNH in adults and children (17,18). Injury to the intrahepatic vascular endothelium with ensuing localized circulatory disturbances was postulated as a possible mechanism.

Pathology The typical macroscopic appearance is of a firm, nodular, mass with a dense central stellate scar and radiating fibrous septa that divide the lesion into lobules of various size (6,19,20) (Fig. 42.1A–C). The lesion is sharply demarcated from the surrounding liver tissue but has no true capsule. The central scar is clearly seen macroscopically in approximately 50% of the cases (3); however, in some of the cases it is absent and the fibrous septa may be poorly developed. The lesion is light brown or yellowish gray and usually occupies a superficial position. The average size is 5 cm and the lesion uncommonly exceeds 10 cm in diameter. Occasionally, it is exophytic or pedunculated. Larger lesions may have foci of hemorrhage or necrosis.

▪ Figure 42.1 Focal nodular hyperplasia (FNH). A and B: Laparoscopic appearance of FNH. Both images show protruding lesions with central depressions (arrows) corresponding to central scars. C: Cut surface of a resected specimen of FNH showing a central scar (arrow) and cirrhosis-like appearance. D: Low-power view of an FNH shows a central fibrous scar, with

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fibrous septa forming nodule-like structures.

P.1204 Microscopically, FNH closely resembles the cirrhotic liver because the fibrous septa create a picture that is similar to that of regenerative nodules (Fig. 42.1D). The differentiation may be difficult in the absence of clinical information. However, a confident diagnosis of FNH can be made with a needle biopsy if the sample is known to come from a mass. The hepatic parenchyma between the septa may include all the components of normal liver including cords of hepatocytes, sinusoids, and Kupffer cells; however, it often lacks the normal liver architecture and may be devoid of central veins and portal tracts (6,20,21,22). Features of chronic cholestasis with accumulation of copper (demonstrated by rhodanine stain) and copper-binding protein (demonstrated by Victoria blue stain) are common (22). The Kupffer cells are usually active and show normal uptake of technetium-99m ( 9 9 m Tc) sulfur colloid, which is different from most cases of hepatic adenomas. Characteristically, the fibrous septa contain numerous bile ductules and blood vessels, as well as chronic inflammatory cells that may form a dense infiltrate. Branches of the hepatic artery and portal vein may show intimal and smooth muscle hyperplasia with thickening of their walls (6,20,21,22). Telangiectatic FNH is considered an atypical variant of FNH in which the central scar is replaced by a telangiectatic lesion with radiating septa (13,23,24). This rare subtype is more likely to be symptomatic as a result of hemorrhage and necrosis. Recently, it has been suggested that telangiectatic FNH may be closer to hepatic adenoma and should be referred to as telangiectatic hepatocellular adenoma (23). Another rare subtype is mixed adenomatous and hyperplastic FNH (3,9).

Clinical Manifestations and Natural History In most of the cases, FNH is asymptomatic and detected incidentally on imaging studies performed for unrelated reasons or during surgery. Hepatic biochemical tests are typically normal and the serum level of α-fetoprotein is not elevated. Abdominal discomfort may be the presenting symptom in a minority of patients (25,26). Abdominal pain is rare and should prompt an evaluation for other causes. Early reports have suggested that women taking OCPs were more likely to be symptomatic (27,28) but this has not been supported by reported in later publications. Some patients may present with hepatomegaly, abdominal mass, or abdominal tenderness but most (approximately 85%) will have normal findings in the physical examination (3). Sudden abdominal pain may be related to rupture or bleeding that is distinctly rare (29,30). The association of rupture with OCPs, although suggested by early studies, remains doubtful (27,29,30,31,32,33). Fibrolamellar hepatocellular carcinoma (HCC) may be mistaken for FNH (34) or may occur in the same liver (35). However, malignant transformation has not been unequivocally described in FNH, and there is no evidence that FNH it is a precursor of HCC or fibrolamellar carcinoma. This is in contrast to hepatic adenoma in which malignant transformation has been well documented. The prognosis of patients with FNH is almost invariably excellent. Most patients remain asymptomatic and exhibit no significant changes in lesion size over time (36). Occasionally, FNH may regress (37,38) and only a small minority (90%) in the diagnosis of hemangioma and is generally considered to be superior to CT scan for this purpose (57,122,123,124,125). It has a special value for the diagnosis of hemangiomas smaller than 2 cm in size and in patients with contraindications to the use of iodine-based intravenous contrast. A hemangioma usually appears as a wellcircumscribed lesion that shows a moderately elevated signal on T2-weighted images and a low signal on T1-weighted images. The increased signal on T2-weighted images is typically less intense than that demonstrated by a simple cyst. Similar to the findings on CT scan, contrast enhancement with gadolinium shows a centripetal nodular filling on the arterial phase, which is considered by many to be a pathognomonic finding (Fig. 42.7A–D). Venous and delayed phases show progressive enlargement and coalescence of the peripheral nodules with variable degree of central filling (124,126). As in CT scan, larger hemangiomas commonly do not fill in on delayed enhanced images. They may show central cystic areas that are as bright as simple fluid, such as cerebral spinal fluid. Small ( Table of Contents > Volume 2 > Section IX - Benign and Malignant Tumors: Cystic Disorders > Chapter 44 - Hepatocellular Carcinoma

Chapter 44 Hepatocellular Carcinoma Jordi Bruix Fernanda S. Branco Carmen Ayuso

Key Concepts z

Hepatocellular carcinoma (HCC) is a neoplasm that has well-defined risk factors, such as chronic viral infection and excessive alcohol intake. These induce chronic liver disease, that is, cirrhosis, and induce genetic damage, leading to cancer development.

z

HCC is the leading cause of death in patients with cirrhosis.

z

The sole option to reduce cancer-related death is to detect cancer at an early stage and apply effective therapy. Patients with cirrhosis who would be treated if diagnosed with liver cancer should enter screening protocols.

z

Early detection of HCC should be based on hepatic ultrasonography every 6 months. Unfortunately, tumor marker determination lacks efficacy.

z

Effective therapies for HCC with potential long-term cure include surgical resection, liver transplantation, and percutaneous ablation. Among palliative approaches, the sole approach with positive impact on survival is transarterial chemoembolization.

z

Prevention of HCC should come from avoidance of risk factors by vaccination for the prevention of hepatitis B and maintenance of proper health standards and adequate lifestyle. Antiviral therapy may cure viral infection and hence prevent progression to cirrhosis and cancer.

Until recently, it was frequent to consider hepatocellular carcinoma (HCC) as a cancer with low incidence in the western world. However, recent data show that its incidence has increased in several western countries (1). In addition, cohort studies reveal that HCC is currently the leading cause of death in patients with cirrhosis (2,3). The feasibility of early detection associated with the availability of several effective therapies has permitted encouraging long-term survival after diagnosis, and as a result, the interest in all aspects related to diagnosis and treatment has sharply increased (4). In this sense, it has been recognized that hepatologists play a key role in the management of patients with HCC. They decide whether HCC surveillance is required in patients at risk and are responsible for disease staging and treatment indication. Among this, the most critical decision is the selection of candidates for liver transplantation and their management before and after surgery. In some countries, mostly in Asia, even surveillance and percutaneous treatment (i.e., alcohol injection and

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radiofrequency ablation) are performed by hepatologists because they receive specific training to acquire the needed expertise. In the present chapter we summarize the most relevant issues about epidemiology, diagnosis, and treatment of this neoplasm.

Epidemiology Primary liver cancer is now the fifth most common cancer in the world and the third cause of cancer-related P.1254 mortality. More than half a million cases are diagnosed every year, there being major geographic differences in incidence. The annual incidence rates in eastern asia and sub-Saharan Africa exceed 15/100,000 inhabitants, while the figures are intermediate (between 5 and 15/100,000) in the Mediterranean basin and southern Europe and very low (15.0

+ nodes or DM

5-y tumor-free survival

100%

61%

40%

5%

0%

Prognostic Risk Score is calculated on the basis of bilobar distribution, tumor size 2–5 cm or >5 cm and vascular invasion. PRS, prognostic risk score; DM, distance metastases. From Iwatsuki S, Dvorchik I, Marsh JW, et al. Liver transplantation for hepatocellular carcinoma: a proposal of a prognostic scoring system. J Am Coll Surg 2000;191(4):389–394.

The theoretical advantages of pretransplant chemoembolization are attractive. Because most, if not all, of the blood supplied to HCC is from the arterial system, the ischemia induced by arterial embolization makes the tumor more susceptible to the effects of the applied chemotherapeutic agent. In theory, one can also deliver higher doses of chemotherapeutic agents directly to the tumor than that possible through systemic use. We and others have used chemoembolization both in an elective setting at the time the tumor is first discovered, and at the time of liver transplantation. Intraoperative chemoembolization is intended to reduce the number of viable tumor cells that liver mobilization associated with total hepatectomy releases into the bloodstream. For patients on the waiting list for transplantation, chemoembolization has been used to reduce the risk of continued tumor growth as well as to reduce the risk of spread at the time of hepatectomy. In nonrandomized applications, several authors believe they have obtained improved survival with both methods of chemoembolization. In 1997 Majno et al. from Paris reported the successful use of chemoembolization to downstage tumors that were more than 3 cm in diameter (76). In some patients, they observed complete necrosis of the tumor. Patients with these responses who underwent subsequent transplantation experienced a significant improvement in tumor-free survival compared to patients with either an incomplete response or to those who did not receive chemoembolization (Fig. 45.2). More recent studies, though, have not shown a significant survival advantage to those patients undergoing transarterial chemoembolization (TACE) and liver transplantation (77,78). Tumor size seemed to be one of the most important prognostic factors among the patients in these reports, with those having a tumor greater than 5 cm in diameter experiencing a ten times greater incidence of recurrence than those with smaller tumors.

Table 45.6. Adjuvant Therapy with Liver Transplantation for Hepatocellular Carcinoma

Recurrence Author

&u&

Year

N

Therapy

Survival

(%)

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Bismuth

1992

20

Arterial chemoembolization with ethiodized oil

2 y (49%)

—

Carr

1993

11

Pretransplant interferon arterial chemoembolization with doxorubricin and cisplatin postoperative chemotherapy

1 y (91%)

—

Stone

1993

20

Pre- and postoperative doxorubricin intravenously

3 y (59%)

45

Cherqui

1994

9

Preoperative chemoembolization and radiation (5 Gy); postoperative mitoxantrone

3 y (64%)

33

Olthoff

1994

25

Postoperative chemotherapy with doxorubricin and cisplatin fluorouracil

3 y (46%)

20

Majno

1997

54

Chemoembolization with lipiodol mixed with doxorubricin or cisplatin

5 y (55%)

—

As the waiting time for liver transplant candidates with hepatic tumors continued to increase during the last half of the 1990s, the effectiveness of preparative regimens for tumor control waned dramatically. The United Network for Organ Sharing (UNOS) allocation algorithm for cadaveric-donor livers assigned priority to patients with liver dysfunction. Patients with HCC but with preserved hepatic function were not able to P.1274 receive adequate priority until their waiting time (also a factor in the allocation algorithm) exceeded 1 to 2 years, depending on geographic location. Inevitably, continued tumor growth during the prolonged waiting period often obviated successful transplantation either because candidates developed evidence of metastatic disease and were removed from the waiting list or because those that finally received a graft were more likely to have developed unrecognized metastases by the time they received the transplant.

▪ Figure 45.2 Cumulative disease-free survival after liver transplantation for hepatocellular carcinoma associated with cirrhosis: Complete necrosis of the lesion after transarterial chemoembolization TACE (necrosis positive: n = 15), no necrosis after TACE (necrosis negative: n = 39), and no TACE (n = 57). (From Majno PE, Adam R, Bismuth H, et al. Influence of preoperative transarterial lipiodol chemoembolization on resection and transplantation for hepatocellular carcinoma in patients with cirrhosis. Ann Surg 1997;226 (6):688–703 with permission.)

Although UNOS eventually allowed special consideration to patients with favorable hepatic tumors by allowing them to compete in a higher status category normally reserved for patients with severe liver dysfunction, the leaders of many liver transplant programs began advocating additional measures to provide expedited liver transplantation. In addition to the general advocacy to increase the available supply of cadaveric-donor livers through wider use of split-livers (79,80,81), many programs began examining the risks and benefits of using live volunteers to provide donor livers. Using a statistical decision analysis technique that considered a cohort of hypothetical patients with compensated Child A cirrhosis and an unresectable 3.5 cm HCC, Cheng et al. from Boston satisfied themselves that live-donor adult-to-adult liver transplantation offered a 4.5-year increase in tumor-free survival as compared to waiting for cadaveric-donor liver transplantation or no transplant. The advantage persisted in their model even in the face of varying severity of cirrhosis, age, tumor doubling time, tumor growth pattern, blood type, regional transplant volume, initial tumor size, and rate of progression of cirrhosis (82). A similar experience was reported by the Mount Sinai Hospital during the period from 1998 to

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2001—the average waiting time for a deceased donor was 414 days as compared with 83 days for a living donor— proposing that HCC is an ideal indication for living-donor liver transplantation (83). In February 2002, the Model of End-Stage Liver Disease (MELD) system was implemented in the United States. Livers from cadaveric donors are now allocated according to a patient's score that is based on their international normalized ratio (INR), creatinine level, and bilirubin level. Patients with HCC most often do not have decompensation of their cirrhosis so the transplant community decided to implement a separate point system that would provide HCC patients with access to organs before their disease progressed beyond the point that they were eligible for transplantation. The Milan criteria have been used to define which patients are eligible for liver transplantation by UNOS standards, that is, patients must have one tumor less than 5 cm or up to three tumors, none of which may exceed 3 cm in diameter. Documentation of the presence of tumor is through imaging and a positive biopsy, AFP more than 200 ng/mL, or previous ablative therapy of the lesion. Points were assigned on the basis of prediction of survival for patients with stage I and II disease (84). With the introduction of the MELD system for liver allocation in adult patients who underwent transplant, the incidence of transplantation for HCC has risen dramatically. In 2001, 2.8% of liver transplants in the United States were for a diagnosis of HCC with or without cirrhosis, and this rose to 7% (434 of 6,186) in 2004. Since the origination of the MELD system, the point allocation for patients with HCC has been adjusted and currently only patients with Stage II disease are eligible for point upgrades. Patient survival rates after liver transplantation for HCC are acceptable, with the 5-year survival being 61.1% in a recent review P.1275 of patients transplanted between 1996 and 2001. This rate is lower than that for patients transplanted without HCC (5-year survival approximately 70%), but remains acceptable (85). As the full impact of our worldwide epidemic of HCV infection reaches its acme, the prospect of a similarly overwhelming population of patients with HCC ought to cause us considerable alarm. Whereas HCC may best be prevented by more effective early treatment of viral hepatitis, the absolute number of patients with established cirrhosis that are at risk for cancer—although a relatively small percentage of the total—is likely to be staggering. Therefore, under the assumption that transplantation offers the best chance of tumor-free survival for these patients, and with the supply of donor livers from cadaveric sources falling even further behind demand from all patients with liver disease (many with far better long-term survival prospects than patients with tumor), the burden on families, friends, and other volunteers to provide pieces of their livers should give us all pause. Although a case-by-case focus on the needs of our own patients ought to be our primary role as physicians, a more global oversight of our results, with a particular emphasis on donor safety and health, needs to be established.

Annotated References Bruix J, Sherman M, Llovet JM, et al. EASL Panel of Experts on HCC. Clinical management of hepatocellular carcinoma. Conclusions of the Barcelona-2000 EASL conference. European Association for the Study of the Liver. J Hepatol 2001;35(3):421–430. A summary of an important consensus conference regarding the treatment of hepatoma. Gondolesi G, Munoz L, Matsumoto C, et al. Hepatocellular carcinoma: a prime indication for living donor liver transplantation. J Gastrointest Surg 2002;6(1):102–107. Compelling data supporting the use of living donors for patients with HCC Iwatsuki S, Dvorchik I, Marsh JW, et al. Liver transplantation for hepatocellular carcinoma: a proposal of a prognostic scoring system. J Am Coll Surg 2000;191(4):389–394.

Majno PE, Adam R, Bismuth H, et al. Influence of preoperative transarterial lipiodol chemoembolization on resection and transplantation for hepatocellular carcinoma in patients with cirrhosis. Ann Surg 1997;226:688– 703. Often cited paper demonstrating the influence of preoperative TACE on resection and transplantation for HCC patients with cirrhosis. Marsh JW, Dvorchik I, Subotin M, et al. The prediction of risk of recurrence and time to recurrence of hepatocellular carcinoma after orthotopic liver transplantation: a pilot study. Hepatology 1997;26(2):444–450. Two articles tracing the development in Pittsburgh of a scoring system that attempts to improve the accuracy of predictions of the risk for tumor recurrence following liver transplantation for HCC. Mazzaferro V, Regalia E, Doci R, et al. Liver transplantation for the treatment of small hepatocellular carcinomas in patients with cirrhosis. N Engl J Med 1996;334:693–699. Landmark paper documenting that good results can be achieved when strict criteria are applied.

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76. Majno PE, Adam R, Bismuth H, et al. Influence of preoperative transarterial lipiodol chemoembolization on resection and transplantation for hepatocellular carcinoma in patients with cirrhosis. Ann Surg 1997;226:688– 703.

77. Decaens T, Roudot-Thoraval F, Bresson-Hadni S, et al. Impact of pretransplantation transarterial chemoembolization on survival and recurrence after liver transplantation for hepatocellular carcinoma. Liver Transpl 2005;11(7):767–775.

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Editors: Title:



Copyright ©2007 Lippincott Williams & Wilkins > Table of Contents > Volume 2 > Section X - The Liver in Pregnancy and Childhood > Chapter 46 - The Liver in Pregnancy

Chapter 46 The Liver in Pregnancy Yannick Bacq

Key Concepts z

During normal pregnancy, except for alkaline phosphatase, most values of serum liver tests remain below the upper normal limits established in nonpregnant women. Consequently, increased levels of aminotransferases, bilirubin, or serum bile acids usually indicate the presence of liver disease. By contrast, an increase in serum alkaline phosphatase levels in pregnancy is not specific for liver disease because it may be of placental origin.

z

The liver disorders that occur in pregnancy can be divided into three groups: (a) Liver diseases unique to pregnancies that are specifically pregnancy related; (b) intercurrent liver diseases in pregnancy, that is, acute liver disease occurring fortuitously during pregnancy; and (c) chronic liver diseases that may be revealed by pregnancy, or more often diagnosed fortuitously during pregnancy.

z

It is essential that liver disease in pregnancy is recognized and understood because certain disorders can threaten the lives of both mother and infant.

z

Liver disorders unique to pregnancy include the exceptional primary hepatic pregnancy, liver dysfunction associated with hyperemesis gravidarum, intrahepatic cholestasis of pregnancy (ICP), liver disorders of preeclampsia including hemolysis, elevated liver enzymes, low platelets (HELLP) syndrome, and acute fatty liver of pregnancy (AFLP).

z

ICP is a benign disease for the mother but carries a risk for the baby because of the possibility of premature delivery and sudden fetal death. Generalized pruritus is the main symptom. Serum bile acid and aminotransferase levels are increased, although the γ-glutamyl transpeptidase levels may be normal or only slightly increased.

z

AFLP is a form of hepatic failure associated with coagulopathy and occasionally encephalopathy and hypoglycemia. An association has been found between AFLP and a defect of long-chain 3-hydroxyacyl coenzyme A dehydrogenase (LCHAD) in the fetus. Women in whom AFLP develops and their offspring should undergo deoxyribonucleic acid (DNA) testing for the main associated genetic mutation (G1528C) in the gene coding for LCHAD.

z

Certain liver diseases that can occur in anyone, pregnant or not, are more severe during pregnancy (e.g., viral hepatitis E and herpes simplex hepatitis). Other disorders can be precipitated by pregnancy or during postpartum, such as cholelithiasis and Budd-Chiari syndrome.

z

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Pregnancy in patients with advanced chronic liver disease is rare, although

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patients with treatable liver diseases, such as autoimmune hepatitis and Wilson disease, may regain fertility and should be maintained on treatment during gestation. By contrast, successful pregnancy in patients with mild chronic liver disease, such as viral hepatitis B or C, is common. Pregnancy after liver transplantation may be associated with prematurity and increased maternal complications, but not with teratogenicity.

P.1282 Liver disease in a pregnant woman can make the consulting physician uneasy. Most gastroenterologists and hepatologists are unfamiliar with the pregnant state and the liver diseases associated with it, and pregnancy is rarely seen in patients with severe chronic liver disease. Also, the stakes are higher for these patients, given the presence of a second life in the form of the fetus. The distress on the part of the consultant is well founded because pregnancy is a state of altered, although normal, physiology. Certain disorders of the liver are unique to pregnancy and not comparable with liver diseases in nonpregnant patients. Furthermore, some conditions that can affect anyone, pregnant or not, may follow an unusually severe course in the pregnant woman. Despite these problems, the care of these otherwise young and healthy women is gratifying, and most return to good health simply by being delivered of the infant. Recent advances in our understanding of liver diseases during pregnancy have simplified and rationalized the approach to these patients.

The Liver in Normal Pregnancy The changes involving the liver during normal pregnancy have been discussed in a review of the literature (1).

Physical Examination Spider angiomata and palmar erythema are common during pregnancy and usually disappear after delivery. In late pregnancy, physical examination of the liver is difficult because of the expanding uterus.

Ultrasonographic Examination Ultrasonographic examination reveals no dilatation of the biliary tract, but increases in fasting gallbladder volume and residual volume after contraction are noted.

Pathology Standard and ultrastructural examination of the liver during normal pregnancy reveals no or minimal abnormalities.

Hemodynamics The plasma volume increases steadily between weeks 6 and 36 of gestation (by approximately 50%). The red cell volume also increases, but the increase is moderate (approximately 20%) and delayed. Consequently, the total blood volume increases, with hemodilution reflected by a decrease in the hematocrit value. It is necessary to bear this phenomenon of hemodilution in mind during the interpretation of all the serum concentrations during pregnancy. The plasma volume and red cell volume decrease rapidly after the termination of pregnancy, aided by the loss of blood at delivery. Cardiac output increases until the second

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trimester and then decreases and normalizes near term. Absolute hepatic blood flow remains unchanged, but the percentage of cardiac output to the liver decreases.

Serum Protein and Lipids The serum albumin levels decrease during the first trimester, and this decrease becomes more accentuated as the pregnancy advances. However, the serum concentrations of some proteins increase, such as α 2 -macroglobulin, ceruloplasmin, and fibrinogen. The serum cholesterol and triglyceride concentrations increase markedly during pregnancy, and except when a pregnant woman is suffering from acute pancreatitis, the measurement of these serum lipid concentrations is rarely useful during pregnancy. The prothrombin time is unchanged during pregnancy.

Liver Tests Knowledge of the changes associated with normal pregnancy is necessary for the interpretation of liver test values and the management of liver diseases during pregnancy (1,2). The serum alkaline phosphatase levels increase late in pregnancy, mainly during the third trimester, as a result of the production of the placental isoenzyme and an increase in the bone isoenzyme level. In most published studies, the serum levels of alanine transaminase (ALT) and aspartate transaminase (AST) have been found to remain within normal limits during pregnancy. Serum γ-glutamyl transpeptidase (GGT) activity decreases slightly during late pregnancy. The total and free bilirubin concentrations are lower than those in nonpregnant controls P.1283 during all three trimesters, as are the concentrations of conjugated bilirubin during the second and third trimesters. The serum 5’-nucleotidase activity is normal or slightly higher during the second and third trimesters compared to that in nonpregnant women. Fasting serum total bile acid (TBA) concentrations usually remain within normal limits, and their routine measurement remains useful for the diagnosis of cholestasis during pregnancy, especially when routine liver function test results are still within normal limits. Therefore, increased values of serum ALT and AST activity, and serum bilirubin and fasting TBA concentrations should be considered pathologic, as they are in nonpregnant women, and prompt further evaluation. The main changes in liver function test results during normal pregnancy compared to nonpregnant women are summarized in Table 46.1.

Table 46.1. Liver Tests in Normal Pregnancy

TESTS NOT AFFECTED BY PREGNANCY Serum transaminase levels (alanine transaminase, aspartate transaminase) Prothrombin time Serum concentration of total bile acids (fasting state) TESTS AFFECTED BY PREGNANCY a Albuminemia (decreased from the first trimester) Alkaline phosphatase levels (increased in second and above all in third trimester)

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Bilirubinemia (slightly decreased from the first trimester) 5′ nucleotidase (slightly increased) γ-Glutamyltransferase (slightly decreased in late pregnancy)

a

Increased or decreased in relation to values in nonpregnant women.

Liver Diseases Unique to Pregnancy Liver diseases unique to pregnancy include primary hepatic pregnancy, hyperemesis gravidarum, intrahepatic cholestasis of pregnancy (ICP), the liver disorders of preeclampsia with HELLP syndrome, and acute fatty liver of pregnancy (AFLP). The main factors in the diagnosis of liver disease in pregnancy are given in Table 46.2. Gestational age at the time of the onset of signs and symptoms can be helpful in the differential diagnosis. Hyperemesis gravidarum begins in the early part of the first trimester. ICP can begin at any time but usually does not present until the second or third trimester. Preeclampsia is a disorder of the second half of pregnancy, and patients with HELLP syndrome usually present in the third trimester. Similarly, AFLP, which can be associated with preeclampsia, is usually a disorder of the third trimester of pregnancy. The main diagnostic features of these liver diseases are given in Table 46.3.

Table 46.2. Main Factors in the Diagnosis of Liver Diseases in Pregnancy

Jaundice Generalized pruritus Nausea or vomiting Pain in epigastrium or right hypochondrium Arterial hypertension and proteinuria Polyuria and polydipsia without diabetes mellitus Thrombocytopenia

Primary Hepatic Pregnancy On exceedingly rare occasions, the inferior surface of the right lobe of the liver is the site of ectopic implantation (Fig. 46.1). Such patients may present early in gestation with hemoperitoneum resulting from hepatic hemorrhage. If the

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pregnancy progresses toward term, the patient presents with a mass in the liver. Primary hepatic pregnancy can be diagnosed by ultrasound examination or computed tomography scan (3), and termination of pregnancy by laparotomy is recommended in view of the risk of rupture.

Hyperemesis Gravidarum Nausea and vomiting are common symptoms of early pregnancy, occurring in up to 50% of all pregnancies, corresponding to “morning sickness.” By contrast hyperemesis gravidarum occurs much less frequently, complicating approximately 0.5% to 1.5% of pregnancies (4,5). There is no clear demarcation between common symptoms and severe forms, and therefore, there is no universally accepted definition. Hyperemesis gravidarum can be defined as persistent vomiting associated with weight loss greater than 5% of prepregnancy body weight and large ketonuria (5). Hyperemesis gravidarum leads to dehydration, and hospitalization is usually required. Liver involvement, as described in the subsequent text, is common in this condition (6).

Pathology Liver biopsy is rarely needed to confirm this diagnosis, given its typical clinical presentation. When performed, it shows surprisingly little. There is no inflammation, but centrilobular vacuolization, necrosis with cell dropout, and rare bile plugs may be seen (7).

Clinical and biochemical findings This disorder presents early in the first trimester of pregnancy, during weeks 4 to 10 of gestation, with intractable vomiting and associated ptyalism. As a rule, it resolves by the 20th week, regardless of therapy. It is more common during a first pregnancy than in multiparous women. In the modern era, liver disease P.1284 P.1285 is inconspicuous and jaundice is rare. This was not the case before the widespread use of intravenous fluids; for example, Charlotte Brontë, the author of Jane Eyre, died in 1855 with nausea, vomiting, and jaundice during the fourth month of her first pregnancy.

Table 46.3. Main Diagnostic Features of Liver Diseases in Pregnancy

QUESTIONING Term of pregnancy, past medical history with emphasis on the history of pruritus during previous pregnancy or oral contraception, pruritus during current pregnancy, abdominal pain, nausea or vomiting, polyuria and polydipsia, drug treatment CLINICAL EXAMINATION Temperature, blood pressure, liver examination (difficult during late pregnancy), herpetic vesicles on skin or mucosa BLOOD TESTS Routine liver function tests (Table 46.1; liver function tests in normal pregnancy)

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Glycemia, creatininemia, electrolytes and uricemia Full blood count including platelets Prothrombin time Viral hepatitis and cytomegalovirus serology Possible measurement of serum total bile acid levels when cholestasis is suspected (not a routine test) URINE TESTS Proteinuria and bacteriuria ULTRASONOGRAPHY OF THE LIVER AND BILE DUCTS EVOLUTION OF SYMPTOMS AND LIVER FUNCTION TESTS AFTER DELIVERY

▪ Figure 46.1 Intrahepatic pregnancy demonstrated by computed tomography. A: A cut from below the dome of the liver showing skull bones of the fetus and the placenta invading the hepatic substance. B, C: Lower cuts demonstrating fetal position with the spine protruding from the inferior surface of the liver. (Permission of Professor Caroline A. Riely.)

When the liver is involved, the most striking abnormality is elevation of aminotransferase levels, with ALT levels exceeding AST levels and both readings usually in the low hundreds but rarely as high as 1,000 IU. Increases in bilirubin levels occur but are less striking. When the patient is treated with gut rest and intravenous fluids, the abnormalities resolve. Pregnancies complicated by hyperemesis gravidarum have been associated with transient hyperthyroidism, and an association between the liver involvement and the hyperthyroidism is

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possible (8). Affected patients may be thought to have hepatitis or gastric outlet obstruction resulting from peptic ulcer disease. Hepatitis serologies are useful in the differential diagnosis. Abdominal pain is not a typical complaint.

Maternal and fetal outcome Many affected patients respond to rehydration and a short period of gut rest followed by reintroduction of a diet rich in carbohydrates and low in fat. Thiamine supplementation may be recommended for women who have vomited for several weeks to prevent Wernicke's encephalopathy. Antiemetics including promethazine, metoclopramide, ondansetron, and droperidol may be useful (9,10). Corticosteroids are reported to improve the appetite and have been proposed in this condition (11,12). Enteral nutrition through gastric or duodenal intubation is effective and preferable to the parenteral route (13). Despite the severity of the illness and attendant weight loss, infants born after affected pregnancies do not differ in regard to birth weight, gestational age, and birth defects from infants born after pregnancies unaffected by hyperemesis gravidarum (4,14).

Pathophysiology The pathogenesis of this disorder remains unclear, but liver involvement, like thyroid involvement, appears to be secondary to the disorder itself, not a causative factor. Infection with Helicobacter pylori may play a role (15), and a predominance of female offspring in affected pregnancies has been noted (16). It is presumed that gestational hormones, many of which peak in the early part of pregnancy, affect both the liver and the thyroid.

Intrahepatic Cholestasis of Pregnancy ICP occurs during the second or third trimester and disappears spontaneously after delivery. The prevalence of ICP varies widely by country. It is common in Scandinavia and even more common in Bolivia and Chile. In Chile, the prevalence in 1974 to 1975 was reported to be 15.6%, ranging from 11.8% to 27.7%, according to ethnic origin (17). For unknown reasons, the prevalence has more recently appeared to decrease (to between 4.0% and 6.5%) (18,19). Generally, ICP is more common in twin pregnancies (20).

Pathology Liver biopsy is rarely necessary for the diagnosis. Histopathology is characterized by pure cholestasis, sometimes with bile plugs in the hepatocytes and canaliculi, predominantly in zone 3. Inflammation and necrosis are not usually observed, and the portal tracts are unaffected (21).

Clinical and biochemical findings Pruritus, which is the main symptom, is very uncomfortable and difficult to tolerate. It is often generalized but predominates on the palms and soles. It is more severe at night and disturbs sleep. Pruritus usually disappears within the first few days of delivery. The clinical examination findings are normal except for evidence of scratching. Fever, if present, is usually caused by an associated urinary tract infection. Approximately 10% to 20% of patients have jaundice. The greater frequency of jaundice in some studies may be a consequence of

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concomitant urinary tract infection (22). ICP with jaundice but without pruritus is rare. Patients do not experience abdominal pain or encephalopathy. Ultrasonographic examination reveals no dilatation of the biliary tract. Measurement of serum ALT activity is a sensitive test for the diagnosis of ICP. Patients with ICP frequently exhibit significant increases in serum ALT activity that suggest acute viral hepatitis, which should be ruled out with suitable serologic tests (23). Liver histology usually does not reveal necrotic lesions, and the ALT level elevations may be secondary to an increase in membrane permeability. The serum GGT activity is normal or only slightly increased, the serum 5’-nucleotidase activity is often slightly increased, and the serum TBA concentrations are increased (24). A relationship between maternal serum bile acid levels and fetal distress has been found (25,26) and evaluation of the serum TBA concentration has been recently suggested as a means of fetal assessment in patients with ICP (27). At the present time, however, no consensus has been reached concerning the usefulness of evaluating the serum TBA concentrations in the obstetric management of patients with ICP (28). Little or no correlation has been found between the serum TBA concentrations and other liver test values (23). The serum bile acid concentration and serum ALT activity decrease rapidly after delivery and, as a rule, normalize in a few weeks. P.1286 Recently, the measurement of serum glutathione-S-transferase, a maker of hepatocellular integrity, has been proposed to distinguish ICP from “benign pruritus gravidarum” (29). The prothrombin time is usually normal. It may become abnormal in severe cholestasis with jaundice or in patients who have been treated with cholestyramine. The abnormality is caused by vitamin K deficiency, which should be anticipated and treated before delivery to prevent hemorrhage. Such therapy contributes to a good maternal prognosis.

Maternal and fetal outcome The maternal prognosis is good, but cholestasis frequently recurs in subsequent pregnancies. The administration of oral contraceptives to women with a history of ICP may rarely result in cholestasis, but ICP is not a contraindication for oral contraceptives. Oral estroprogestogen contraception with a low dose of estrogen can be initiated after the liver test values have normalized. The patient should be informed of the possibility of pruritus during such contraception. ICP does carry a risk for the fetus (30). The main complication of ICP is prematurity, which is more frequent in patients with ICP than in the general population (19). The rate of prematurity varies greatly according to the study and may be increased because of the high rate of multiple pregnancies in patients with ICP (23). The other complication of ICP is the risk of sudden fetal death. The prevalence is approximately 1% to 2% but varies according to studies. Sudden fetal death rarely occurs before the last month of pregnancy.

Pathophysiology The cause of ICP is unknown. The results of previous epidemiologic and clinical studies suggest that genetic, hormonal, and exogenous factors play a role. Genetic factors may explain the familial cases and the higher incidence in some ethnic groups, such as the Araucanos Indians of Chile (17). A nonsense mutation of the ABCB4 (MDR3) gene has been found in a child with progressive familial intrahepatic cholestasis type 3 (PFIC 3) and in three mothers suffering from cholestasis during pregnancy (31). In this familial study, the infant with PFIC 3

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was homozygous for the ABCB4 mutations, whereas the mothers with ICP were heterozygous. The ABCB4 gene codes for the translator of phosphatidylcholine across the canalicular membrane into bile. In the absence of phospholipids in bile, bile acids can injure the canalicular membrane, leading to cholestasis. Several other mutations of the ABCB4 gene were subsequently found in patients suffering from ICP (32,33,34). However, the role of ABCB4 in the pathogenesis of ICP has not been clearly established and the prevalence of such mutations in patients with a clearly defined phenotype of ICP is still under evaluation (35,36). Defects in the ATP8B1 gene, which is associated with progressive familial intrahepatic cholestasis type 1 (PFIC1) and benign recurrent intrahepatic cholestasis (BRIC), have also been found in patients with ICP, but it seems that this gene is not a major contributor to ICP (37). A role of estrogens has been clearly established in ICP. Animal studies have shown that estrogens, in particular ethynyl estradiol, are cholestatic. Genetically determined abnormalities may lead to unique hepatic reactions to estrogens or to dysfunction of estrogen metabolism (30). Progesterone metabolism is also involved in the pathophysiology. Abnormalities of progesterone metabolism, especially elevated levels of serum sulfated metabolites, have been found in women with ICP (38). The formation of large amounts of sulfated progesterone metabolites, possibly related to greater 5-α and 3-α reduction, may in some genetically predisposed women result in a saturation of the hepatic transport system(s) involved in the biliary excretion of these compounds (39). One study has shown that oral natural progesterone prescribed for threatened premature delivery can trigger ICP in predisposed women (23). The intake of progesterone may place an additional load on the sulfated metabolite transport system. Progesterone treatment should therefore be avoided in pregnant women, especially late in pregnancy or when the patient has a history of ICP. Some characteristics of ICP suggest that exogenous factors may be associated with an underlying genetic predisposition: (a) ICP recurs in only 60% to 70% of pregnancies in multiparous women, (b) seasonal variability has been observed in several countries, and (c) the prevalence of ICP has decreased in Sweden and Chile. For example, a deficiency in selenium may be a factor involved in the pathophysiology of ICP (40).

Medical and obstetric management Hydroxyzine (25 to 50 mg/day) may alleviate the discomfort of pruritus. Cholestyramine (8 to 16 g/day) decreases the ileal absorption and increases the fecal excretion of bile salts. Its effect on pruritus is limited. The efficacy of Sadenosyl-L-methionine is a matter of debate (18,41,42). The most promising treatment is ursodeoxycholic acid. In some case reports and several open and controlled trials, ursodeoxycholic acid has been effective in ICP (38,42,43,44,45,46). The bile acid patterns in meconium are influenced by cholestasis of pregnancy and are not altered by treatment with ursodeoxycholic acid (45,46). Ursodeoxycholic acid relieves pruritus, improves liver function test values (Fig. 46.2), and prevents prematurity. No side effects have been reported for mothers or babies. Therefore, ursodeoxycholic acid (usually 500 mg twice a day or 15 mg/kg per day) appears to be safe during late pregnancy and may be useful in relieving cholestasis P.1287 and improving fetal prognosis in patients with ICP, especially those with severe disease. The mechanism of the beneficial effect of ursodeoxycholic acid for the mother and the baby in ICP remains speculative. Like in chronic liver diseases,

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ursodeoxycholic acid, which is a hydrophilic bile acid, may decrease signs of cholestasis in the mother by affording cytoprotection against the hepatotoxic effects of the hydrophobic bile acids and by improving the hepatobiliary bile acid transport. In ICP, ursodeoxycholic acid may also have a specific effect by improving the transport of bile acid across the placenta.

▪ Figure 46.2 Treatment of intrahepatic cholestasis of pregnancy (ICP) with ursodeoxycholic acid (UDCA). This patient had experienced ICP during a previous pregnancy. Regular surveillance during the current pregnancy was proposed and once the diagnosis of recurrent ICP had been confirmed treatment with UDCA was initiated. Serum total bile acid (TBA) concentration (TBA, upper normal limit: 6 µmol/L) and serum alanine aminotransferase (ALT) activity (ALT, upper normal limit: 35 IU/L) improved and the patient delivered at 38 weeks of gestation. (Yannick Bacq, personal data, 2005)

It is often difficult to decide the best time for delivery, and no consensus has been clearly established. When cholestasis is severe (e.g., if the patient has clinical jaundice), delivery should be considered at 36 weeks of gestation if the fetal lungs have matured, or as soon thereafter as possible (19).

Preeclampsia Liver Disorders Livers disorders associated with preeclampsia are certainly the most frequent causes among the liver diseases unique to pregnancy (47). Preeclampsia is a multisystem disorder of enigmatic etiology and pathogenesis presenting in the latter half of pregnancy (48,49). It complicates 3% to 5% of all pregnancies and is a major cause of maternal and fetal mortality. Despite the importance of this disorder, even its definition is still debated (50). The disease is thought to start early in pregnancy, with abnormal implantation of the trophoblast, which leads to restricted perfusion of the placenta. The fall in systemic vascular resistance typical of normal pregnancy does not occur in patients with preeclampsia; their sensitivity to vasospasm is enhanced, with resultant poor perfusion of and injury to a variety of organs, including the liver. A variety of factors is suspected to

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play an important role in the mechanism of the disease, some inherited, some immunologic. The disorder is more common in primiparas and in multiple gestations with twins or triplets (51,52). It is also more common in multiparous women whose first pregnancy was complicated by preeclampsia (53). Being the offspring of either a father or a mother who was born of a preeclamptic pregnancy increases the risk of preeclampsia in the next generation (54). A possible role for an inherited procoagulant state was suggested (55,56,57), but then refuted (58). A link to insulin resistance syndrome is possible (59,60). Abnormalities in endothelial function, probably mediated by nitric oxide, can be demonstrated in women with a history of preeclampsia (61). Antioxidant treatment was shown to decrease the incidence of preeclampsia in susceptible women (62), which suggests a role for oxidative stress in this condition (63). Preeclampsia may result from paternal or fetal effects, and immune factors may play a role (48). An excess of male offspring from affected pregnancies has been noted (64). Preeclampsia is more common in couples who have cohabited for only a short period (65) and in multiparous women who then become pregnant by a different partner (66). The typical presentation is hypertension with proteinuria, although both conditions are not found in all patients with this multisystem disease. Patients may also have renal failure, seizures (eclampsia), pancreatitis, or pulmonary edema. Preeclampsia has long been P.1288 known to affect the liver in a variety of ways including HELLP syndrome.

Hemolysis, elevated liver enzymes, low platelets syndrome The HELLP syndrome is defined as hemolysis (usually subclinical, with characteristic schistocytes and burr cells on smear), elevated liver enzyme levels (usually elevated aminotransferase levels, with AST exceeding ALT), and low platelet numbers in a patient with preeclampsia. Affected women are less likely to be primiparous and tend to be older than the average woman with preeclampsia (67). The hepatic histology is that of preeclamptic liver disease, with periportal hemorrhage and fibrin deposition. Little correlation is found between the degree of histologic aberration and the severity of the clinical findings. Fat may be seen, but as macrovesicular fat distributed in modest quantities throughout the liver lobule and not as the microvesicular centrizonal fat typical of AFLP (68). Despite similar settings and occasional clinical overlap, these two conditions are histologically distinct (69). The clinical presentation of HELLP varies markedly, with no symptom other than abdominal pain recorded in more than 50% of patients (53). The pain is usually located in the midepigastric region, right upper quadrant, or substernal region. Many patients have nausea, vomiting, and malaise, which suggest a diagnosis of viral hepatitis. Jaundice is present in approximately 5% of patients (53). Most cases are diagnosed during the third trimester, although the condition may present postpartum. In a large series of 437 patients who had 442 pregnancies with HELLP syndrome, 70% of cases occurred before delivery and 30% after delivery, 11% developed before 27 weeks of gestation and 18% after 37 weeks (53). Most, but not all, patients have the hypertension and proteinuria that are typical of preeclampsia. The diagnosis usually rests on clinical grounds, although imaging studies, particularly computed tomography (Fig. 46.3) and magnetic resonance imaging, are useful in detecting the complications of hepatic infarct,

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hematoma, and rupture (70). Hepatic hematoma may be missed by these techniques but detected laparoscopically (71). Liver biopsy should be approached with caution, given the association of hematoma and rupture with HELLP.

▪ Figure 46.3 Hepatic involvement in a 24-year-old primipara with severe preeclampsia. A: Abdominal computed tomography performed after delivery by cesarean section showing subcapsular ischemic lesions in the right lobe. B: Follow-up image 7 months later showing complete recovery. (Courtesy of Béatrice Scotto, MD.)

The outcome for the mother is usually good, with a maternal mortality rate of 1.1% in a large series (53), and the condition starts to reverse with delivery. A review of deaths collected from many centers demonstrated that stroke is the most common cause of death, followed by cardiac arrest and disseminated intravascular coagulation (72). No correlation between any laboratory test value (e.g., platelet count, or aminotransferase or lactate dehydrogenase level) and adverse maternal outcome was reported in another study (73). Rare patients experience severe liver disease with fulminant hepatic failure leading to death (74). Diabetes insipidus has been reported in HELLP syndrome and also in AFLP (75). The main risk for the fetus is prematurity. These babies do not have any increased risk of liver disease or thrombocytopenia, and their outcome is similar to that of babies of a similar gestational age (76,77). Management is supportive and may include transfer to a medical intensive care unit, with ventilatory support and dialysis provided in severe cases. The cornerstone of therapy is delivery, although temporizing management with intensive monitoring may be useful for some patients with mild disease (78). Corticosteroids have been shown to improve laboratory test P.1289 values and allow a delay in delivery (79,80,81). Long-term follow-up has shown an increased risk of obstetric complications in subsequent pregnancies but no tendency for a repetition of the HELLP syndrome (67).

Hepatic hematoma and rupture In rare pregnant patients, a hematoma develops beneath the Glisson capsule. This may remain contained, or rupture of the liver capsule may result in hemorrhage into the peritoneal cavity from multiple lacerations in which the

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capsule has been lifted from the surface. Rupture usually occurs in the setting of HELLP syndrome. Histology of the portion of the liver adjacent to the rupture shows periportal hemorrhage and fibrin deposition, along with neutrophil infiltrate, suggestive of hepatic preeclampsia (53,82). Some patients do not have thrombocytopenia or typical preeclampsia (83). Clinically, affected patients have abdominal pain and, when the liver has ruptured, swelling of the belly from hemoperitoneum, along with shock. The aminotransferase levels are usually slightly raised, but values in the range of 4,000 to 5,000 IU are occasionally seen. Computed tomography or magnetic resonance imaging of the body is more dependable than ultrasonography for detecting these lesions (70). The management of a contained hematoma is supportive. Patients with rupture are best managed by a team experienced in liver trauma surgery (84). Liver transplantation is used when the hemorrhage cannot be contained (85,86,87). Patients who survive have no hepatic sequelae and have been documented to have normal subsequent pregnancies (67). A report of recurrent episodes in subsequent pregnancies suggested a predisposition of affected women, resulting from some underlying condition, perhaps an inherited procoagulant state (88).

▪ Figure 46.4 Acute fatty liver of pregnancy in a 24-year-old primipara. This woman had experienced nausea and vomiting, abdominal pains, and jaundice in late pregnancy. A transvenous liver biopsy was performed postpartum— (A) intact lobular architecture (hematoxylin and eosin, 200×) and (B) typical microvesicular fatty infiltration in hepatocytes and features of cholestasis (400×). (Courtesy of Anne de Muret, MD.)

Acute Fatty Liver of Pregnancy AFLP was distinguished as a specific clinical entity unique to pregnancy in 1940 (89). It is a rare disease and its incidence was estimated to be 1 per 13,328 deliveries at the Los Angeles County University of the Southern California Medical Center (90) and 1 per 15,900 in Santiago, Chile (91). Early diagnosis and prompt delivery have dramatically improved both maternal and fetal prognosis, as perhaps has the recognition of the disease, and an article from Los Angeles County states the incidence to be 1 in 6,659 births (92). In addition, in a recent prospective study including 4,377 deliveries in Southwest Wales, AFLP was found in five patients (i.e., 1 per 875 deliveries) (47).

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Pathology Liver biopsy is the best way to confirm the diagnosis of AFLP, but because it is invasive, it is not always performed. Also, we can now take advantage of noninvasive procedures to demonstrate fat in the liver and exclude other liver diseases, such as viral hepatitis. Nevertheless, liver biopsy may be useful in atypical cases. The overall architecture of the liver is not altered. The characteristic picture is a microvesicular fatty infiltration of the hepatocytes, which are swollen. The droplets are minute and surround centrally located nuclei, so that the cytoplasm has a foamy appearance (Fig. 46.4). In a few cases, rare, large fat vacuoles are associated with the microvesicular steatosis. The microvesicular fatty infiltration is most prominent in the pericentral zones and midzones (zones 2 and 3) and usually spares a rim of periportal cells. The droplets stain with oil red O, which is specific for fat. The histologic features of cholestasis (i.e., bile thrombi or bile P.1290 deposits within hepatocytes) are common. Inflammation is not prominent but is also common (93). The histologic features are not always evident, and cases of AFLP have been misdiagnosed as hepatitis. Necrosis with acidophilic bodies is inconspicuous, and massive panlobular hepatocellular necrosis, as in fulminant viral hepatitis, is not seen. On the other hand, the liver may appear disorganized, with impressive lobular disarray and pleomorphic hepatocytes (94). Electron microscopy confirms the presence of fat droplets and has shown nonspecific changes in mitochondrial size and shape (95). A stain specific for fat or electron microscopy is useful for pathologic confirmation of the diagnosis in patients with ballooning of the cytoplasm but no evident vacuolization. Therefore, whenever AFLP is suspected, a piece of the liver biopsy specimen should be reserved before paraffin embedding and processed appropriately with special stains to confirm the presence of fat in the hepatocytes. The pathologic changes normally reverse rapidly after delivery, and AFLP is not associated with progression to cirrhosis (94).

Clinical and biochemical findings As a rule, AFLP is a disease of the third trimester that may occur during any period of gestation. However, some reports have detailed cases presenting at 22 (96) or 26 weeks of gestation (97). The onset of disease is never after delivery, but the diagnosis may be made after delivery. The frequency of twin gestations is increased among patients with AFLP (14% to 19% vs. approximately 1% in the general population), and 7% of triplet pregnancies have been reported to be complicated by AFLP (52). The most frequent initial symptoms are nausea or vomiting, abdominal pain (especially epigastric), anorexia, and jaundice. In the past, jaundice was almost always seen during the course of the disease, but because of earlier diagnosis, prompt delivery, and the diagnosis of milder cases, we now see affected patients without jaundice. The size of the liver is usually normal or small. Patients with AFLP rarely have pruritus but may have concurrent ICP (98). Approximately half of affected patients have high blood pressure or proteinuria, which are the main symptoms of preeclampsia (93). On the other hand, some affected patients do not have any of these signs. Patients may demonstrate asterixis and encephalopathy, with or without coma, and some have pancreatitis. Esophagitis and Mallory-Weiss syndrome related to severe vomiting have been reported. Gastrointestinal bleeding secondary to the esophageal lesions, in addition to gastric ulceration related to shock, has been reported.

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Genital bleeding is frequent. These hemorrhages are exacerbated by associated coagulation disorders. Ascites may be present and is partially related to portal hypertension (91). Polyuria and polydipsia have been noted in about 5% of patients with AFLP (93), and an association between transient diabetes insipidus and AFLP has been reported (99). The serum aminotransferase levels are raised, but usually the level is not as high as that in acute viral hepatitis. The bilirubin level is almost always increased. Patients may demonstrate hypoglycemia. In severe cases, the prothrombin time is increased and the fibrinogen level decreased. These coagulation disorders are caused by hepatic insufficiency, disseminated intravascular coagulation, or both. A low platelet count is usual in AFLP and is not always associated with other signs of disseminated intravascular coagulation. Thrombocytopenia may be the most striking laboratory feature and normalizes spontaneously after delivery. The diagnosis of AFLP should always be considered when thrombocytopenia occurs during late pregnancy and should always prompt the performance of liver function tests, particularly determination of the aminotransferase levels. Renal failure (mainly functional) and hyperuricemia are usual. Ultrasonography of the liver may show increased echogenicity (100). Computed tomography may be useful for the diagnosis, and a liver density lower than usual may be demonstrated by Hounsfield unit values in the liver that are equal to or lower than those in the spleen (101). The findings on imaging studies may be normal; a recent study showed that the findings on computed tomography, which is more sensitive than ultrasonography, were normal in half of the patients with AFLP (102). In clinical practice, these complementary examinations should not delay delivery, particularly in severe cases, which can usually be diagnosed on clinical grounds with routine biologic data.

Maternal and fetal outcome The maternal mortality rate of AFLP was very high before 1970 (approximately 90%) (93). The maternal prognosis has currently improved greatly, and maternal mortality is less than 10%. This improvement is principally related to early delivery, advances in intensive care support for patients with severe forms, and also the detection of patients with less severe forms. Most recover completely after delivery, without sequelae. However, one patient remained in prolonged coma after hemorrhagic shock (103), and cases of neurohypophyseal insufficiency have been reported, which, in one case has been associated with definitive diabetes insipidus (104). AFLP may recur during subsequent pregnancies, although recurrence is not the rule. At least 25 cases without recurrence have been reported; 17 patients had a normal pregnancy and 4 had two normal pregnancies after AFLP. However, at least six cases of recurrence have been reported since 1990. In the first case, both P.1291 episodes of AFLP were confirmed by histologic examination of the liver biopsy specimen, and the mother and babies recovered (105). In the second case, although healthy children were delivered by cesarean section, both babies died at 6 months (106). Steatosis of the liver was present in these neonates and associated with a deficiency of β-oxidation of fatty acids. The mother had a third pregnancy, which was uneventful, and the infant did not have such a deficiency. In the third case, the baby died in utero during the first episode of AFLP (91). During the recurrence 5 years later, emergency cesarean section performed at 36

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weeks resulted in a live birth, and the outcome was good for both mother and baby. The outcome was favorable for mothers and babies in three other cases of recurrence reported in the literature. Mothers who have experienced AFLP should be informed of the risk for recurrence and closely followed up during subsequent pregnancies. Follow-up should be both clinical and biologic (e.g., liver function tests, tests for uricemia, and platelet counts twice monthly during the third trimester). Until 1985, fetal mortality was reported to be as high as 50% (94). Early delivery has resulted in an improved fetal prognosis (107), and the final outcome for infants delivered alive is usually considered to be good. However, in view of the possibility of congenital enzyme deficiency involving intramitochondrial βoxidation of fatty acids, these infants should be closely followed up from birth.

Pathophysiology AFLP belongs to a group of liver diseases characterized by microvesicular steatosis, including Reye's syndrome, sodium valproate and tetracycline toxicity, and Jamaican vomiting sickness. All these conditions are considered to be caused by abnormalities of mitochondrial function. Microvesicular steatosis may occur in several other drug-induced, toxic, and viral liver diseases. The cause of AFLP remains unknown, although good progress toward a better understanding of this disorder has recently been made. An association of inherited defects in the β-oxidation of fatty acids with AFLP is now well established. A case of long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) deficiency in a 4-month-old baby born to a mother who had had AFLP and HELLP syndrome at 36 weeks of pregnancy was reported in 1994 (108). Both parents were heterozygous for LCHAD deficiency. Hepatic steatosis or HELLP syndrome has also been reported in several mothers of babies with LCHAD deficiency (109,110). β-Oxidation of fatty acids, measured by the activity of LCHAD in skin fibroblast culture, was studied in 12 women who had had AFLP (110). LCHAD activity was reduced in eight of them, consistent with heterozygosity for LCHAD deficiency. Four women had no deficiency. The eight heterozygous women had a total of nine pregnancies complicated by AFLP. Of the nine offspring delivered from these pregnancies, four were confirmed to be homozygous for LCHAD deficiency. Three other infants died with a clinical picture compatible with this diagnosis. The two other infants were healthy at 18 and 24 months of age and had LCHAD activity in the heterozygous range. The five husbands tested were heterozygous (110). These findings show that a deficiency in the β-oxidation enzyme in the fetus may lead to maternal hepatic steatosis in late pregnancy, especially if the mother is heterozygous for the deficiency. Two mutations (G1528C and C1132T) have been observed in the gene coding for LCHAD in three families with children having LCHAD deficiency whose mothers had had AFLP or HELLP syndrome (111). More recent work shows that acute fatty liver may occur regardless of the mother's genotype if her fetus is deficient in LCHAD and carries at least one allele with the G1528C mutation (112). In affected families, a prenatal diagnosis based on sampling of chorionic villi has proved both feasible and accurate (113). These forms of AFLP associated with a genetic deficiency of β-oxidation have not been observed in all countries; the common mutation (G1528C) was not found in 14 women with AFLP observed consecutively in a French hospital (114). Another defect in β-oxidation, a deficiency of carnitine palmitoyltransferase I, has also been associated with AFLP (115), and DNA analysis for this deficiency is available (116). No familial cases (i.e., AFLP in

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mother and daughter) have been reported.

Medical and obstetric management AFLP must be considered an obstetric emergency. AFLP usually does not resolve before delivery, and if delivery is delayed, complications such as hemorrhage and intrauterine death may develop. Consequently, the primary therapy for AFLP is early delivery. The choice of the route of delivery remains the decision of the obstetrician and must be appropriate for the individual clinical situation. Generally speaking, if the patient is in labor and in good general condition and no sign of fetal distress is detected, then vaginal delivery may be attempted with careful monitoring of the mother and baby (117). For patients with severe disease, urgent delivery must be considered, usually by cesarean section, after correction of the coagulation disorders, especially those related to thrombocytopenia. The etiology of AFLP is not known, and no specific medical treatment is available. Esophagitis should be treated with appropriate drugs to prevent bleeding. The blood sugar levels should be monitored and P.1292 hypoglycemia treated by a continuous intravenous infusion of glucose. Patients with fulminant hepatic failure are best managed in an intensive care unit before and after delivery; intensive care remains the cornerstone of management. Two patients with serious disease that continued after delivery (which is unusual) were treated successfully by liver transplantation (118,119), and auxiliary transplantation has been used successfully in this setting (120). Nevertheless, the role of liver transplantation in AFLP is probably limited. Early diagnosis and prompt delivery of the infant of a patient with AFLP should avoid the difficult decision about later liver transplantation.

Intercurrent Liver Disease in Pregnancy In addition to the disorders unique to pregnancy, pregnant women are susceptible to diseases that can affect anyone. Some common disorders can take a fulminant course in pregnant women, hepatitis E being the most frequent example. Furthermore, pregnancy predisposes a woman to the development of the usual liver diseases, such as cholelithiasis.

Acute Viral Hepatitis The response of a pregnant woman to acute infection with the viruses that cause hepatitis varies, depending on the virus.

Hepatitis A Pregnant women who contract hepatitis A are not at increased risk of severe disease from this infection (121), although the risk for premature labor may be increased in women who are seriously ill during the third trimester (122).

Hepatitis B In patients with documented acute hepatitis B, pregnancy is not associated with increased mortality (123) or teratogenicity (124). Infection during gestation should not prompt termination of the pregnancy. Women exposed to hepatitis B during gestation may be vaccinated without any reported increase in congenital

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anomalies (125); the vaccine is immunogenic in this setting (126).

Hepatitis E This infection occurs both in epidemics and sporadically in many parts of the world (e.g., India, Pakistan, northern Africa, and Mexico). Women in the third trimester are more likely to have clinical disease than are other persons. The fatality rate in this group is as high as 25% (127,128,129). It can be difficult to distinguish fulminant hepatitis E from AFLP. Women in the third trimester of pregnancy should carefully consider the risks associated with travel to areas where this disease is endemic. Hepatitis E can cause acute hepatitis in the newborn and can be transmitted in utero to the fetus (127,129,130).

Hepatitis caused by herpes simplex virus and other viruses When it occurs in the third trimester of pregnancy, hepatitis resulting from a primary systemic infection with herpes simplex virus is likely to be severe. Half of the reported cases of fulminant herpetic hepatitis have occurred in pregnant women (131). Affected patients may have a “viral” syndrome that includes fever and upper respiratory tract symptoms. Despite marked abnormalities in their aminotransferase levels and prothrombin time, these patients are usually anicteric at presentation. A vesicular eruption is diagnostically useful but may not yet be visible at presentation. Cultures and histology of liver biopsy specimens are helpful in the differential diagnosis, which should include severe liver disorders associated with pregnancy, such as AFLP and HELLP syndrome. Therapy with acyclovir is successful, and affected women need not be delivered of infants early. Acute infection with coxsackievirus B can cause a similar picture of acute hepatic failure (132). Why hepatitis E and herpes simplex hepatitis are so much more severe and associated with such increased hepatic injury in the third trimester of pregnancy is unclear. Alterations in T-cell function have been reported in pregnancy and may be related to this enhanced susceptibility (133). Herpes simplex hepatitis is known to be more severe in certain immunocompromised states, such as chronic immunosuppression after transplantation.

Biliary Tract Disease and Pancreatitis Pregnancy decreases gallbladder motility and increases the lithogenicity of bile (134). Pregnancy has long been considered a risk factor for the development of gallstones; epidemiologic studies confirm an association with an increased risk for gallstones, but only for a 5-year period after pregnancy. Thereafter, the risk drops back to that of the never-pregnant population (135). In adolescents with gallstones, a history of pregnancy is common (136). Ultrasonographic studies show that gallstones and biliary sludge may accumulate throughout gestation and resolve with a return to nonpregnant physiology (137,138). In a recent prospective study of 3,254 women, the cumulative incidence of new sludge, new stones, or progression of baseline sludge to stones P.1293 was 10.2%, by 4 to 6 weeks postpartum (vs. 5.1% by the first trimester). In the same study, 28 women (0.8%) underwent cholecystectomy within the first year postpartum (139). Acute cholecystitis may occur in pregnancy. Operative cholecystectomy can be

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performed during gestation, although it may increase maternal and fetal morbidity, particularly in the first trimester (140,141,142). In a large series of cholecystectomy in women, the procedure was only rarely performed during pregnancy (143), suggesting that acute cholecystitis, which is unresponsive to conservative medical management, is not a common occurrence during pregnancy. Recently, less invasive approaches to the problem of biliary lithiasis in pregnancy have been successful. Choledocholithiasis can be managed by endoscopic retrograde cholangiopancreatography with sphincterotomy (144,145). Laparoscopic cholecystectomy has also been reported to be successful in pregnancy (142,146), although the risk of morbidity may be increased (147). Acute pancreatitis may complicate pregnancy. The serum amylase and lipase levels are normal during pregnancy, so abnormal values warrant attention (148). Pancreatitis usually occurs in the setting of cholelithiasis (149,150), and gallstones should be sought in any affected patient. Gallstone pancreatitis should be treated aggressively, either operatively (151) or endoscopically (144,152). Pancreatitis complicating pregnancy may be associated etiologically with AFLP or preeclampsia (153). Mild pancreatitis may occur in association with severe hyperemesis gravidarum, presumably as “refeeding pancreatitis.” Familial hypertriglyceridemia, exacerbated by the physiologic hypertriglyceridemia of pregnancy, may present during pregnancy with pancreatitis (154). Hyperparathyroidism may be associated with pancreatitis in pregnancy (155,156). A choledochal cyst may present during pregnancy, with abdominal pain, a mass, and jaundice (157). Such presentations may represent cases of congenital choledochal cyst exacerbated by the effects of pregnancy on biliary motility. Spontaneous rupture of a choledochal cyst (158) and of an apparently normal common hepatic duct (159) have been reported in pregnancy.

Hepatic Vein Thrombosis (Budd-Chiari Syndrome) Both pregnancy and oral contraceptive therapy are associated with a hypercoagulable state (160). The frequency of hepatic vein thrombosis (BuddChiari syndrome) is increased in women using oral contraceptives (161). Reports from India suggest that it is also more common in pregnant women, usually manifesting immediately after delivery (162,163). Several reports have linked acute Budd-Chiari syndrome during pregnancy in western women with an underlying procoagulant state, such as primary antiphospholipid syndrome (164), anticardiolipin antibody (165), factor V Leiden mutation (166,167), or thrombotic thrombocytopenic purpura (168). The prognosis for pregnant women with this syndrome is ominous, as it is for pregnant women with idiopathic veno-occlusive disease. Liver transplantation has been used as a lifesaving measure (166,169), but such patients may survive with conservative measures, including delivery and anticoagulation. Recurrence has been reported in a patient whose anticoagulants were stopped when she became pregnant again (165). Nevertheless, subsequent successful, uncomplicated pregnancy has been reported for patients with a history of Budd-Chiari syndrome associated with oral contraceptives or an underlying myeloproliferative syndrome (170).

Drug-Induced Hepatic Injury Because of concern about fetal teratogenicity, pregnant women in general take fewer drugs than those who are not pregnant. When they do take drugs, however, they run the same risk for adverse drug reactions as others. Potentially fatal hepatotoxicity has been reported in pregnant women undergoing

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antiretroviral therapy for human immunodeficiency virus (HIV) infection (171). Acetaminophen overdose leading to death has been reported (172). On the other hand, no increased incidence of such adverse reactions during pregnancy has been documented. For example, 1,300 pregnant women took isoniazid for tuberculosis without ill effect (173).

Metastasis to the Liver The liver is not palpable in normal pregnant women, and therefore, hepatomegaly detected on physical examination requires immediate evaluation. Patients with extensive tumor invasion of the liver may present with abdominal or back pain, rupture of the liver, or hepatic failure. The usual source is a common tumor, such as carcinoma of the colon (174,175) or pancreas (176). Gestational trophoblastic neoplasm (hydatidiform mole) can be a source of tumor spread to the liver. Breast cancer may also present with hepatomegaly during pregnancy. A patient presenting at 26 weeks of gestation with hypertension and thrombocytopenia, imitating HELLP syndrome, was found to have cholangiocarcinoma (177). It is possible that the modest immunosuppressive state associated with pregnancy promotes extensive tumor spread and growth.

Other Complicating Illnesses Sepsis, particularly urinary tract infections, may be associated with jaundice in pregnant women (178), P.1294 as they are in the nonpregnant state. Echinococcal cysts of the liver have been reported during pregnancy (179,180).

Pregnancy in Women with Chronic Liver Disease Monitoring of liver disease is necessary when its presence is known before pregnancy, and this requires cooperation between the obstetric team and hepatologists. Most patients with severe liver disease are not women of childbearing age or they are infertile because of the associated anovulatory state. Nevertheless, some of these women can become pregnant, and when they do, some special problems arise. On the other hand, most young women with chronic but nonsevere liver disease can have full-term pregnancies without any particular risk. However, there is the question of the effect of liver disease or its treatment on the fetus. Certain drugs should not be stopped during pregnancy because of the risk of relapse of the liver disease due to withdrawal of treatment. This is the case, for example, with immunosuppressive treatment of chronic autoimmune hepatitis and with penicillamine, which is used as a copper chelator in Wilson disease (see subsequent text). Other drugs, such as ribavirin used in the treatment of hepatitis C, are strictly contraindicated in pregnancy. In the case of ribavirin, the patient should be clearly informed of the need for effective contraception throughout treatment and during the 6 months thereafter.

Cirrhosis and Portal Hypertension Worsening jaundice with progressive liver failure, ascites, and hepatic coma have been reported during the course of pregnancy in women with cirrhosis (181,182). Whether the exacerbation of hepatic dysfunction is caused by gestation or is merely coincident with it is unclear. What is clear, however, is that women with cirrhosis can often sustain pregnancy without any worsening of hepatic function (182). Published reports document an increased incidence of stillbirths and

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premature delivery in such women (182,183,184). The fertility of women with noncirrhotic portal hypertension, as seen in congenital hepatic fibrosis or portal vein thrombosis, is not diminished; therefore, pregnancy is encountered in this setting with some frequency (185,186). A worsening of preexisting portal hypertension may be anticipated because of the marked increase in blood volume and azygos flow that occurs during normal pregnancy. Variceal hemorrhage during pregnancy or labor has been reported (183,184,186,187). It is not clear whether the incidence of variceal hemorrhage in pregnant patients is higher than that in nonpregnant patients with known varices. Furthermore, a history of hemorrhage in one gestation does not predict the outcome of subsequent pregnancies (188). Sclerotherapy or endoscopic band ligation has been reported to be successful in pregnant women with variceal hemorrhage (185,189,190). Prevention of hemorrhage due to esophageal varices in women with known cirrhosis who desire pregnancy is based on classical treatment with β blockers and/or endoscopic ligature. An upper endoscopy is therefore usually performed before pregnancy. Prophylaxis with β blockers may be continued during pregnancy, but newborns should be monitored during the first days of life because of risks of hypoglycemia and bradycardia.

Specific Liver Diseases Alcoholic liver disease Alcoholic liver disease is often associated with infertility. However, most alcoholics do not have liver disease. Pregnancy in a fertile alcoholic woman can result in fetal alcohol syndrome in the infant, which includes typical facies, malformations, and developmental delay. Several such infants have been reported to have liver disease, with fatty liver and portal and perisinusoidal fibrosis suggestive of alcoholic liver disease (191). For the most part, however, liver disease or its treatment is not teratogenic. If they can succeed in getting pregnant, women with liver disease are not at increased risk of having children with congenital anomalies. On the other hand, they do have more maternal problems during pregnancy, and the risk of prematurity or stillbirth is greater.

Chronic hepatitis B In general, pregnancy is well tolerated by women who are chronic carriers of the hepatitis B virus (HBV) (192); reactivation of the virus with exacerbation of disease during or after gestation is the exception rather than the rule (182,193). The placenta forms an excellent barrier against transmission of this large virus, and intrauterine infection with HBV is rare. It does occur, however, probably as a result of transplacental leakage, as in threatened abortion (194,195). The major problem for women who are chronic carriers of HBV is the risk of maternal-toinfant (vertical) transmission of infection at delivery. Transmission at birth is more likely if the mother is positive for P.1295 hepatitis B early antigen (HBeAg) (196) or has high circulating levels of HBV DNA (197). The rate of transmission may be lower if the delivery is by cesarean section (198). However, this is usually not indicated because appropriate immunoprophylaxis for the newborn with both HBV hyperimmune globulin and vaccine is efficient to interrupt transmission. Routine prenatal screening of all pregnant women for hepatitis B surface antigen (HBsAg) is now the standard of care (199). Infants born to infected mothers should be protected by the

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recommended combination of vaccine and hepatitis B immunoglobulins at birth (199), although the emergence of mutant strains of the virus in such infants has been reported (200). Infants born to carriers of the HBV precore mutant who are positive for antibody anti-HBe and with high levels of HBV DNA in their serum are at risk for fulminant hepatitis B during the first 2 to 4 months after birth (201). Immunoprophylaxis should therefore be given to the infants of all mothers who are HBsAg positive, regardless of their HBe status. In women with very high HBVDNA levels, vertical transmission of HBV can occur despite vaccination of the child. In eight such highly viremic HBsAg-positive women (HBV-DNA levels above 150pg/mL approximately equivalent to 1.2 × 10 9 geq/mL), a treatment with lamivudine (150 mg/day) during the last month of pregnancy decreased the HBVDNA level and was associated with a reduction of the risk of child vaccination breakthrough (202). Hepatitis D (δ) virus can also be transmitted from mother to infant at birth (203).

Chronic hepatitis C Uneventful pregnancy without worsening disease or fetal complications has been reported in women with hepatitis C (204). Several studies have demonstrated that aminotransferase levels decrease as the pregnancy progresses, whereas the HCV load, measured by polymerase chain reaction, increases during the course of gestation (205,206,207). Early evidence suggests that the hepatic histopathology may worsen during gestation (208). Whether pregnancy has any effect on the progression of this disease remains to be proved (209). Transmission from mothers who are chronic carriers to their offspring may occur but appears to be much less efficient than the vertical transmission of hepatitis B (210). Rates of transmission were initially said to be proportional to the mother's viral burden, as indicated by the measurement of HCV RNA by polymerase chain reaction, and greatly enhanced transmission was supposed to occur in women coinfected with HIV, who have very high levels of viremia and rates of transmission ranging from 6% to 30% (211,212,213). More recent studies have not shown a correlation between a large viral load and increased maternal–infant transmission (205,207). Testing the newborn can be misleading. Early after birth, antibodies acquired from the mother result in positivity for HCV, and transient viremia can be seen in infants who later test negative. Cord blood can be negative for HCV RNA, although the infant is subsequently shown to be HCV RNA positive (205). An overall transmission rate of 5% according to testing performed 1 year after birth, regardless of the mother's HIV status, has been reported (205). No association with breast-feeding has been shown, and breast-feeding is not contraindicated (214,215). It may be prudent for mothers who are HCV infected and choose to breast-feed to consider abstaining from breast-feeding if their nipples are cracked and bleeding (215). The rate of transmission is not lower in infants delivered by cesarean section, and cesarean section is not recommended for women with chronic HCV infection alone (216). Hepatitis C acquired in infancy appears to have a benign course, although on biopsy some affected children have chronic hepatitis (210).

Hepatitis G/GB and hepatitis TT It is unclear whether the hepatitis G/GB virus and the hepatitis TT virus are pathogenic. Both have been shown to be transmitted efficiently from mother to infant, with sustained infection in the offspring, in the absence of any liver disease (217,218,219).

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Autoimmune hepatitis A distinctive clinical characteristic of autoimmune hepatitis is the rapid and complete (or nearly complete) remission that occurs in response to immunosuppression with corticosteroids, given either alone or in combination with azathioprine. The disorder presents frequently in young women, many of whom become anovulatory in response to the active and severe hepatitis, which sometimes progresses to cirrhosis by the time of diagnosis. Women appropriately treated for this disease with corticosteroids and azathioprine regain their fertility, and successful pregnancies without any increase in fatality have been reported (220). The aminotransferase levels may decrease during the second and third trimesters of pregnancy, and some have advocated lowering doses of immunosuppressive drugs during gestation (221). Untreated patients may go into remission during pregnancy (222). The underlying disease may flare up after delivery, and women should be followed up carefully for the first 4 to 6 weeks postpartum, particularly if the immunosuppressive dose has been decreased. Worsening of the underlying disease or even initial presentation of autoimmune hepatitis has been reported during pregnancy (220). Azathioprine has not been reported to be teratogenic in this setting of low-dose therapy. Successful treatment of infertility in these patients, with in vitro fertilization/embryo transfer, has been reported (223).

Primary biliary cirrhosis The effects of pregnancy on women with primary biliary cirrhosis have been reported to be variable although studies are scarce. Pregnancy may be associated with an increase in cholestasis that resolves after delivery, regression of cholestasis, or progression of disease P.1296 including the complications of portal hypertension (224,225,226,227). Ursodeoxycholic acid has been used for ICP with no reports of adverse effects and can be used in patients with primary biliary cirrhosis at the very least during the second and third trimester. In a recent report of nine pregnancies in six women with ursodeoxycholic acid–treated primary biliary cirrhosis, pregnancy was associated with improvement of liver function tests (228).

Wilson disease Women with ovulatory failure secondary to Wilson disease regain their fertility, often quite rapidly, when treated. Either they or their physicians may be tempted to discontinue therapy during gestation, but, as in nonpregnant patients with Wilson disease, cessation of therapy can have devastating effects and should not be attempted (229,230). Successful pregnancy without teratogenicity has been reported in patients taking penicillamine or trientine (231,232,233,234). Zinc treatment has also been successful during pregnancy (235). Clearly, the major risk to the mother created by stopping therapy greatly outweighs the potential risk to the fetus, and therapy should be continued because successful pregnancy in treated women is the rule (231). Doses of penicillamine or trientine may be reduced during the last trimester (231).

Benign liver tumors (hepatic adenoma, focal nodular hyperplasia, hemangioma) Hepatic adenoma associated with the previous use of oral contraceptive agents

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has been reported to enlarge or rupture during subsequent pregnancy (236,237,238,239), and rupture is associated with high mortality (236). Successful surgical resection of a large hepatocellular adenoma performed at 13 weeks of gestation has been reported; the patient complained of increasing epigastric pain and the tumor (7 cm × 9 cm) was in the left hepatic lobe (240). A recent study of 216 women with focal nodular hyperplasia showed no association between oral contraceptive use and change in lesion size. Twelve women in this group became pregnant, with no change in lesion size or problems with pregnancy (241). An enlargement of a focal nodular hyperplasia associated with the previous use of oral contraceptive was however reported in one pregnant woman (242). The occurrence of liver hemangiomas during pregnancy has been reported (243). The results of a recent prospective study of 94 women (181 hemangiomas) suggests that endogenous and exogenous female sex hormones may play a role in the pathogenesis of liver hemangiomas, although significant enlargement occurs only in a minority of patients (244). These liver hemangiomas are rarely symptomatic and complications are exceptional.

Familial hyperbilirubinemia The unconjugated hyperbilirubinemia of Gilbert syndrome is not exacerbated by pregnancy (245). In Dubin-Johnson syndrome, however, conjugated hyperbilirubinemia may worsen during gestation but returns to prepregnancy levels after delivery (246). Women with type II Crigler-Najjar syndrome have been reported to have uncomplicated pregnancies during phenobarbital therapy (247,248).

Porphyrias Porphyrias, genetic disorders of heme metabolism that may be exacerbated by estrogenic hormones, occasionally cause problems for affected women and their fetuses during pregnancy. Porphyria cutanea tarda has rarely been reported to present initially during pregnancy (249). Acute attacks often complicate the course of pregnancy in patients with acute intermittent porphyria, variegate porphyria, or hereditary coproporphyria (250,251), and they may result in intrauterine growth retardation or, rarely, maternal death. On the other hand, many women with acute porphyria, particularly those with little clinical expression of the defect, weather pregnancy with no problems. Precipitation of an initial attack of acute intermittent porphyria by the nausea and vomiting of hyperemesis gravidarum, coupled with antiemetic therapy, has been reported (252).

Liver transplantation Patients who have undergone transplantation regain their fertility promptly— within weeks of surgery. Young women should be counseled about the risks of becoming pregnant and encouraged to use effective contraception, preferably barrier methods, until their immunosuppressive regimen has been stabilized (253,254). A review of 136 pregnancies after liver transplantation reported to the National Transplantation Pregnancy Registry has shown that most are successful, with no birth defects in the offspring (255). The number of premature infants is increased, and women whose renal function is compromised do not do as well. Ten episodes of acute rejection occurred during pregnancy in this study, and as a result three women lost their grafts. Seven of the women died, three within a year of the pregnancy. The risk of teratogenicity with standard

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immunosuppressive agents, including prednisone, azathioprine, cyclosporine, and tacrolimus, is low (256). It is preferable to delay pregnancy until the immunosuppressive regimen has been stabilized (i.e., 1 to 2 years after grafting). Surveillance for infection, such as that with cytomegalovirus, should be increased during gestation. If the results of liver tests become abnormal, then liver biopsy should be performed to establish the nature of the dysfunction. Increased monitoring of the P.1297 blood levels of cyclosporine and other immunosuppressive agents is necessary, both before and for several months after delivery (257). Such pregnancies should be considered high risk and managed together with experts in maternal–fetal medicine. Breast-feeding has been discouraged because of concerns about potential immunosuppression of the newborn, but many examples of successful breast-feeding without adverse effects have been reported (255). Liver transplantation has been accomplished during pregnancy, with and without fetal wastage (255,258,259,260). Livers from living related donors have also been transplanted during pregnancy (261). Obviously, such heroic surgery must be considered with extreme care in this setting. If a condition prompting transplantation is caused (e.g., AFLP) or exacerbated (e.g., Budd-Chiari syndrome) by pregnancy, then prompt diagnosis, followed by termination of the pregnancy with maximum support for the mother, is the treatment of choice. Auxiliary partial orthotopic liver transplantation is an attractive alternative in the setting of liver disease that should resolve after delivery, with regrowth of the patient's native liver and atrophy of the transplanted liver (262).

Acknowledgment The author thanks Professor Caroline A. Riely for her collaboration in the previous editions.

Annotated References Armenti VT, Herrine SK, Radomski JS, et al. Pregnancy after liver transplantation. Liver Transpl 2000;6:671–685. A review of the complications and outcomes of 136 pregnancies after liver transplantation. Three stillbirths but no birth defects were recorded. Prematurity and low birth weight were common, as were preeclampsia and infection in the mothers. Such pregnancies should be considered high risk. Bacq Y, Zarka O, Bréchot J-F, et al. Liver function tests in normal pregnancy: a prospective study of 103 pregnant women and 103 matched controls. Hepatology 1996;23:1030–1034. A prospective study of pregnant patients and matched controls. The results of standard liver tests in all three trimesters were considered. Levels of alkaline phosphatase rose in the third trimester. The total bile acid levels did not differ between the pregnant women and the controls. The levels of bilirubin and GGT were lower in the pregnant women than the controls. AST and ALT values remained within normal limits. Castro MA, Fassett MJ, Reynolds TB, et al. Reversible peripartum liver failure: a new perspective on the diagnosis, treatment and cause of acute fatty liver

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of pregnancy, based on 28 consecutive cases. Am J Obstet Gynecol 1999;181:389–395. A review of a large case series. The authors emphasize the high incidence of renal compromise and significant hypoglycemia and plead that liver transplantation be avoided in those patients whose liver disease is reversible. Hamid SS, Wasim Jafri SM, Khan H, et al. Fulminant hepatic failure in pregnant women: acute fatty liver or acute viral hepatitis? J Hepatol 1996;25:20–27. A study from Pakistan of 12 patients with fulminant hepatic failure in pregnancy. Most patients were shown to have hepatitis E. Mortality was 16%. Heneghan MA, Norris SM, O’Grady JG, et al. Management and outcome of pregnancy in autoimmune hepatitis. Gut 2001;48:97–102. A review of the King's College experience of 35 pregnancies in 18 women with autoimmune hepatitis. Two patients presented during pregnancy, and four had flares. No birth defects were noted despite azathioprine therapy in some. Ibdah JA, Bennett MH, Rinaldo P, et al. A fetal fatty acid oxidation disorder as a cause of liver disease in pregnant women. N Engl J Med 1999;340:1723– 1731. A study of families affected by long-chain 3-hydroxyacyl coenzyme A dehydrogenase deficiency. The pregnancies of mothers of deficient fetuses carrying the Glu474Gln mutation were complicated by AFLP or HELLP, a unique example of maternal illness caused by deficiency in the fetus. Ko CW, Beresford SA, Schulte SJ, et al. Incidence, natural history, and risk factors for biliary sludge and stones during pregnancy. Hepatology 2005;41:359–365. A prospective study on biliary sludge and stones during pregnancy and postpartum in 3,254 women. Sludge or stones were found on at least one ultrasound study in 5.1% by the second trimester, 7.9% by the second trimester, and 10.2% by 4 to 6 weeks postpartum. Twenty-eight women (0.8%) underwent cholecystectomy within the first year postpartum. Prepregnancy body mass index and serum leptin were risk factors for gallbladder disease. Kumar A, Beniwal M, Kar P, et al. Hepatitis E in pregnancy. Int J Gynaecol Obstet 2004;85:240–244. A prospective study of 62 pregnant women in India having jaundice in the third trimester. Twenty-eight patients (45.2%) had hepatitis E and 26.9% of these patients with hepatitis E infection died with fulminant hepatic failure (five patients died undelivered). Vertical transmission of HEV was observed in 33.3% of cases. This study confirms the poor prognosis of hepatitis E during the third trimester of pregnancy. Reyes H, Simon FR. Intrahepatic cholestasis of pregnancy: an estrogen-

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related disease. Semin Liver Dis 1993;13:289–301. An indepth review of cholestasis of pregnancy, including clinical findings and management, in addition to an extensive review of the possible pathogenic mechanisms. Sibai BM, Ramadan MK, Usta I, et al. Maternal morbidity and mortality in 442 pregnancies with hemolysis, elevated liver enzymes, and low platelets (HELLP syndrome). Am J Obstet Gynecol 1993;169:1000–1006. An assessment of a large number of women with HELLP syndrome, detailing presenting signs and symptoms, laboratory results, management, and maternal complications. The HELLP syndrome occurred in 20% of patients with severe preeclampsia and was responsible for five deaths.

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Editors: Title:



Copyright ©2007 Lippincott Williams & Wilkins > Table of Conte nts > Volume 2 > Section X - The Liver in Pregnancy and Childhood > Chapter 47 - Live r Disease in Infancy and Childhoo d

Chapter 47 Liver Disease in Infancy and Childhood Maureen M. Jonas Antonio R. Perez-Atayde

Key Concepts z

Understanding the genetic and molecular control of liver development will elucidate hepatobiliary pathophysiology and provide a framework for understanding disorders of the liver and bile ducts that occur at all ages.

z

Hepatobiliary disorders that occur in both adults and children, such as viral hepatitis and autoimmune hepatitis, share some features, but there may be important differences in epidemiology, natural history, clinical presentation, and therapeutic considerations.

z

Characterization of the genetic defects in several forms of intrahepatic cholestasis illustrates the importance of normal hepatic excretory function, and may explain both severe cholestatic liver disorders in childhood as well as predisposition to liver and biliary tract diseases in some adults.

z

Extrahepatic biliary atresia is the most common cause of end-stage liver disease and the most common indication for liver transplantation in the pediatric age-group. Early diagnosis is critical.

z

Although some genetic diseases or inborn errors of metabolism cause significant liver disease during infancy and childhood, others may have manifestations beginning in or lasting into adulthood.

z

As individuals with cystic fibrosis survive well into adulthood, it has become important to understand the chronic liver disease that develops in some of these patients and devise strategies that may be unique to this large group of patients with a multisystem disorder.

Embryology of the Hepatobiliary System The hepatic diverticulum is seen as early as the 18th day of gestation (2.5-mm stage) as a thickening of the ventral floor of the distal foregut, the future duodenum. The liver diverticulum penetrates the adjacent mesoderm and capillary plexus known as the septum transversum. Cellular interactions between the endoderm and mesoderm result in rapid cell proliferation and the formation of hepatocytes, angioblasts, and sinusoids. By the third and fourth weeks of gestation the growing diverticulum enlarges and branches, projecting into the septum transversum. Division of this diverticulum into a solid cranial portion (hepatic parenchyma) and hollow caudal portion is evident by the 5-mm stage. The hepatic portion differentiates into proliferating cords of hepatocytes and intrahepatic bile ducts while the smaller cystic portion (pars cystica) forms the primordium of the gallbladder, common bile duct, and cystic duct. The budding liver sequentially invades the vitelline veins and then the umbilical (placental) veins. The vitelline veins run from the gut-yolk sac complex to the heart. The caudal ends of the veins persist as the primitive portal veins and the cranial ends persist as the primitive hepatic veins. The hepatocytes grow as thick epithelial sheets intermingling between branching channels of the vitelline veins within the septum transversum to form a system of connecting liver cell plates, P.1306 whereas the proliferative angioblasts become the hepatic sinusoids. The sinusoids, present by 5 weeks' gestation, act as templates for the three-dimensional growth of the hepatic cords. The liver cell plates are initially three to five cells thick. Over time, they gradually transform to one-cell-thick plates, a process that is not complete until 5 years of age. Intrahepatic bile ducts begin to form at 6 weeks' gestation within the hilum of the liver and gradually reach the periphery at 3 months (1). Although the pars cystica is initially hollow, epithelial proliferation obliterates the lumen early in its development. Therefore, the primitive gallbladder and common bile duct consist of solid chords of epithelial cells directly beneath the developing liver in the 6- to 7-mm embryo. Recanalization of the common bile duct and hepatic duct occurs subsequently, until at the 16-mm stage the proximal gallbladder and cystic duct are hollow. At the third month the gallbladder is fully hollow, and the intrahepatic and extrahepatic biliary structures are joined. Bile secretion into the duodenum starts by the fourth month. In the third month the liver begins to store iron, and hematopoietic elements derived from the mesenchyme of the septum transversum localize within the lobules and portal tracts. The liver therefore becomes the major blood-forming organ of the embryo. This function is gradually transferred to the developing bone marrow so that by birth only an occasional focus of hematopoiesis remains in the liver. During fetal life, the falciform ligament conducts the umbilical vein from the umbilicus to the liver. After birth this vein atrophies to form the ligamentum teres. In neonates and infants, the liver accounts for 5% of the total body weight, as compared with 2% in adults.

Development of Hepatobiliary Function The fetus is supplied with a continuous flow of high-carbohydrate, low-fat, and high–amino acid nutrients through the placenta, but the newborn is fed in intervals with milk; a high fat, lower-carbohydrate diet. At weaning there is another shift to an adult-type diet, which includes more carbohydrates and less fat. The liver plays a central role in these adaptations through regulation of carbohydrate, fat, and protein metabolism. The adult pattern of metabolic pathways develops shortly after birth as the blood supply to the liver changes from one dominated by umbilical venous blood to one in which the hepatic artery plays an equally important role. This allows for the development of the functional zones within the liver, each with unique metabolic demands. Zone 1 (periportal) hepatocytes predominantly perform gluconeogenesis, β-oxidation,

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cholesterol biosynthesis, bile acid secretion, ureogenesis, and sulfation of drugs, whereas zone 3 (pericentral) cells perform glycolysis, lipogenesis, ketogenesis, glutamine synthesis, and glucuronidation of drugs. The liver plays an important role in the handling of dietary starches. Fetal glucose utilization approximately equals umbilical glucose uptake. At weaning, two factors allow for increase in hepatic glucose uptake. First is the presence of a highcapacity, low-affinity glucose transporter, GLUT2, which is insulin-independent. The second is glucokinase, which replaces hexokinase as the predominant glucose phosphorylation enzyme within the hepatocyte allowing for specific action upon glucose, and induction by insulin. Throughout gestation the fetus actively stores some of the glucose as glycogen so that hepatic glycogen at birth is about twice the adult concentration at 40 to 60 mg/g of liver. Most of this stored glycogen is utilized in the immediate postnatal period. Reaccumulation begins in the second postnatal week, and glycogen stores typically reach adult levels by the third week. The role of this large store is the maintenance of blood glucose levels during the perinatal period, before other energy sources are available, and before the initiation of hepatic gluconeogenesis. The rate-limiting enzyme involved in gluconeogenesis, phosphoenolpyruvate carboxykinase (PEPCK), rapidly rises after birth. PEPCK is a cytosolic enzyme primarily expressed in the periportal (zone 1) hepatocytes. Glucose-6-phosphatase catalyzes the final step in glucose release from the liver. This enzyme, located within the lysosomes, rises rapidly at term and is hormonally controlled. Although the fetal liver is capable of synthesizing albumin, lipoproteins, enzymes, coagulation proteins, and a variety of carrier proteins after the third month of gestation, concentrations of these proteins are low in fetal plasma. Lipoproteins increase in the first week after birth to levels maintained until puberty. Albumin reaches adult levels after several months in a reciprocal relationship with the primary fetal protein, α-fetoprotein. Ceruloplasmin and complement factors increase to mature values during the first year. Transferrin levels are present in the low adult range at birth and slowly rise to normal adult levels thereafter. Fat storage begins during fetal life. Synthesis of fatty acids by the fetal liver occurs despite low levels of acetyl CoA carboxylase, the rate-limiting step in fatty acid synthesis in the adult liver. The triacylglycerol that accumulated during fetal life is mobilized for local utilization after birth. Bile acids are produced as early as the tenth week of gestation. Chenodeoxycholic acid is predominant. Although glycine is the most common conjugate in adults, in early life more than 80% of the bile acids are taurine-conjugated. In infants, the total bile acid pool size is small; at 32 weeks' gestation the fetus has a bile P.1307 acid pool one sixth that of an adult. In a premature infant, the intraluminal bile acid concentration may fall below the critical micellar concentration of 1 to 2 mmol/L. In addition, there is less effective intestinal reabsorption, inadequate canalicular secretion, and inefficient hepatic uptake of bile acids from the systemic circulation. The cumulative effects of the immature bile acid metabolism and homeostasis in newborns result in relatively inefficient absorption of dietary fats and fat-soluble vitamins, and a tendency toward cholestasis (2). Hepatocytes are responsible for the excretion of numerous substances through bile, including bilirubin, drug metabolites, and heavy metals such as zinc and copper. Bile secretion starts at the beginning of the fourth month of gestation, and the presence of bile in the lumen of the intestine is responsible for the dark green color of meconium. Bilirubin formation is 3 to 4 mg/kg per day in healthy adults and 6 to 8 mg/kg per day in healthy term infants. This difference is due to the greater relative red blood cell mass and shorter red blood cell life span in infants. Infants have lower levels of the conjugating enzyme, bilirubin glucuronyl transferase, and therefore have fewer diglucuronides than adults. When bilirubin conjugates enter the intestinal lumen, normal bacterial flora hydrogenate the carbon double bonds to produce urobilinogens, which are excreted. Neonates lack the bacteria Clostridium ramosum and Escherichia coli and are therefore more likely to absorb bilirubin from the intestine. Bilirubin can also be unconjugated by bacterial or tissue β-glucuronidase, and readily absorbed from the intestine.

Congenital Abnormalities in Hepatobiliary Structure Situs Inversus and Heterotaxia Situs inversus and heterotaxia result in left sided or ambiguous location of the liver within the abdominal cavity, respectively. Either may occur with other anomalies such as in the polysplenia/asplenia syndromes.

Vascular Anomalies Although many variations have been described in hepatic artery anatomy, most do not have clinical significance except when the patient requires hepatic surgery. Congenital absence of the portal vein (CAPV) is a rare but well-described anomaly (2a), and when seen with a spontaneously occurring mesocaval or other portosystemic shunt, is referred to as Abernethy malformation. CAPV may be associated with nodular regenerative hyperplasia of the liver (2) and the Goldenhar's syndrome (3). Children with this anomaly may have elevated serum ammonia, bile acids, and galactose concentrations, as the portosystemic shunt bypasses the detoxifying ability of the liver (4). Other anomalies of the portal vein are occasionally seen, in association with cardiac or urinary tract abnormalities. The presence of multiple serpiginous collateral veins surrounding a small or thrombosed portal vein has been referred to as cavernous transformation of the portal vein . This is an acquired rather than a congenital abnormality and is accompanied by portal hypertension since portal resistance is markedly elevated. It represents the body's effort to maintain hepatopetal portal flow in the face of occlusion of the extrahepatic portal vein. The causes of portal vein thrombosis include umbilical infection (omphalitis), perinatal catheterization of the umbilical vein, pancreatitis, surgical manipulation during splenectomy, and hypercoagulable states including deficiencies of protein C, protein S, or antithrombin III, and the presence of anticardiolipin antibodies or a factor V Leiden gene mutation. Children with cavernous transformation of the portal vein typically come to medical attention within the first decade with splenomegaly or bleeding from esophageal varices. The diagnosis is confirmed by ultrasonography of the extrahepatic portal area with Doppler interrogation. Endoscopic ligation or sclerosis of esophageal varices, portosystemic shunts, and mesenterico-left portal bypass (Rex shunt) are palliative measures. The natural history is such that over time there is a decrease in the frequency and intensity of the hemorrhagic manifestations. Liver histology is usually nondiagnostic with nonspecific findings, which may include fibrosis.

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Biliary Tract Abnormalities Choledochal cysts Choledochal cysts are congenital malformations resulting in cystic dilatation of part or all of the extrahepatic biliary system. The incidence is estimated at 1 in 13,000 to 200,000 live births. They are found in women four times more frequently than in men, and are more prevalent in Asians, specifically the Japanese. The location of the cyst allows for classification into one of five anatomic types as described by Todani (Fig. 47.1) (5). Most are type I, diffuse enlargement of the common bile duct. The etiology of cyst formation is unclear, although there is growing evidence that the dilatation results from an anomalous junction of the common bile duct and the pancreatic duct resulting in a common channel up to 3.5 cm in length, from a normal of 5 mm. This long common channel may allow for the reflux of pancreatic proteases into the extrahepatic biliary tree resulting in cholangitis and stenosis. This hypothesis is supported by high levels of amylase within the cysts, but P.1308 the frequent documentation of prenatal choledochal cysts makes a malformation etiology more likely.

▪ Figure 47.1 Types of choledochal cyst. (From Todani T, Watanabe Y, Narusue M, et al. Congenital bile duct cysts: Classification, operative procedures and review of thirty seven cases including cancer arising from choledochal cyst. Am J Surg 1977;134:263–269.with permission.)

Most patients present within the first decade of life. The classic triad of abdominal pain, jaundice, and palpable right upper quadrant mass occurs in less than 20% of patients. Other common symptoms are fever, nausea, and vomiting, with or without associated pancreatitis. Ultrasonography is the most valuable diagnostic test. Radionuclide scanning may demonstrate the accumulation of tracer within the cyst. Endoscopic retrograde cholangiopancreatography (ERCP) provides delineation of the biliary anatomy, but is not always necessary to confirm the diagnosis. The high incidence of biliary malignancy, reported between 2.5% and 17.5% in Japanese patients, has led to the recommendation of cyst excision. Most tumors are adenocarcinomas, detected at a mean age of 35 years. The cause of the malignant transformation is not known, but may relate to the chronic reflux of pancreatic proteases and the mutagenic potential of secondary bile acids in a stagnant environment. The reconstruction varies on the cyst type, anatomy, and surgical preference; the most common procedures are hepaticoduodenostomy, hepaticojejunostomy, or jejunal interposition.

Gallbladder anomalies Congenital absence of the gallbladder occurs in 1 in 7,500 to 1 in 10,000 individuals. Failure of development of the pars cystica is the likely etiology. As an isolated abnormality this is of little clinical significance although rarely symptoms develop because of calculi in the ductal system. In addition to extrahepatic biliary atresia (EBA), which may accompany agenesis of the gallbladder, other associations include imperforate anus, genitourinary anomalies, anencephaly, bicuspid aortic valve, and cerebral aneurysms. Hypoplasia of the gallbladder has been described. As many as one third of individuals with cystic fibrosis (CF) have small, poorly functioning gallbladders. There is also an association with EBA and trisomy 18. The incidence of double gallbladder is 0.1 to 0.75 per 1,000. The two cystic ducts may converge into a single duct forming a Y-shaped structure, or an accessory gallbladder may lie under the left lobe of the liver, draining into the left hepatic duct.

Extrahepatic biliary atresia—fetal form EBA is usually considered an acquired condition, and is discussed in subsequent text in this chapter. However, there is an embryonic or fetal type that comprises approximately 35% of cases and may be a true congenital biliary tract anomaly (6). This form is characterized by earlier onset of cholestasis and absence of bile duct remnants. Ten percent to 20% of children with fetal-type biliary atresia have associated anomalies. The most common are various combinations that characterize the laterality sequence, such as polysplenia or asplenia, cardiovascular defects, abdominal situs inversus, intestinal malrotation, and vascular aberrations of the portal vein and hepatic artery. Intestinal malrotation alone is seen in 12%. There is speculation that the fetal form of biliary atresia has a different pathologic mechanism than the perinatal type, although this has not been proven. P.1309

Ductal plate abnormalities

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At about the eighth week of gestation, the hepatic precursor cells that lie adjacent to the hilar portal vein vessels form a sleeve-like double layer of cells, which extends toward the periphery along the intrahepatic portal vein branches. This structure has been called the ductal plate (DP). Beginning at 12 weeks' gestation and extending into the postnatal period, the DP undergoes remodeling (7). Individual bile ductules are incorporated into the periportal mesenchyme that surrounds the portal vein branches. During successive periods of fetal life, DP remodeling leads to the formation of the intrahepatic biliary tree. The largest ducts are formed first, followed by segmental, interlobular, and finally the smallest bile ducts. Arrest or derangement in remodeling leads to the persistence of primitive bile duct configurations, or to what Jorgensen termed ductal plate malformation (DPM) (7). The occurrence of DPM at different generation levels of the developing biliary tree gives rise to different clinicopathologic entities, such as congenital hepatic fibrosis (CHF) and Caroli syndrome (8,9). The most common DPM-associated disorder is autosomal recessive polycystic kidney disease (ARPKD) with CHF, which occurs with an incidence between 1 in 6,000 and 1 in 40,000 births. The cysts are rarely macroscopically visible. Microscopically, the portal tracts appear enlarged by connective tissue and contain tortuous and dilated bile duct structures (Fig. 47.2) and incompletely remodeled ductal plates, which are in continuity with the rest of the biliary system. The renal lesion is characterized by radially arranged tubular collecting duct cysts occupying most of the large, externally smooth renal mass. This disorder has been attributed to mutations in PKHD1 on chromosome 6p12, which encodes a protein called fibrocystin. Fibrocystin is localized to the collecting ducts and biliary ducts.

▪ Figure 47.2 Congenital hepatic fibrosis. Expanded portal tracts show persistence of the ductal plate and cystic and tortuous bile ducts. Incidental mild steatosis is also present.

CHF may also be associated with other liver malformations such as von Meyenburg complexes (bile duct microhamartomas), as well as other renal lesions including autosomal dominant polycystic kidney disease, renal dysplasia, and nephronophthisis. Congenital dilatation resulting from DPM of the larger, segmental intrahepatic bile ducts is termed Caroli disease. When this lesion is combined with the changes of CHF, as is typically the case, the disorder is termed Caroli syndrome (see Chapter 43). Mutations in PKHD1 have been found in 32% of adults with CHF/Caroli syndrome (10). Infants with congenital hepatic fibrosis–autosomal recessive polycystic kidney disease (CHF-ARPKD) may have enlarged and severely dysfunctional kidneys. In this setting, hepatic fibrosis may be present, but is rarely an important clinical factor. In older patients, the most significant abnormality is portal hypertension due to the hepatic fibrosis and/or portal vein anomalies, such as duplication of intrahepatic branches. Hematemesis or melena may occur as early as 1 year, but more typically at 5 to 13 years of age. The biochemical parameters of hepatic synthetic function are typically normal, but there is a risk of cholangitis. Treatment may include portosystemic shunting for portal hypertension and aggressive antibiotic therapy for cholangitis. Approaches such as variceal sclerotherapy or pharmacologic management of portal hypertension have been used. In patients with chronic cholangitis and/or progressive hepatic dysfunction, liver transplantation may be indicated.

Bile duct paucity syndromes Paucity of the intrahepatic bile ducts is defined as a ratio of interlobular ducts to P.1310 portal tracts of less than 0.9 (Fig. 47.3). Surgical biopsy or serial needle biopsies may be required to examine at least 20 portal tracts, the recommended sample for this diagnosis, but as few as 5 portal tracts in a percutaneous biopsy may be sufficient in the appropriate clinical setting. Syndromic paucity of the bile ducts, or Alagille syndrome (AS), discussed in subsequent text, is the most common disorder with this finding. Patients with nonsyndromic paucity of intrahepatic bile ducts typically present earlier than those with AS (11). Paucity of the bile ducts has been described in association with a variety of other conditions including Down's syndrome, hypopituitarism, CF, α 1 -antitrypsin deficiency, Zellweger's syndrome, Ivemark's syndrome, and congenital infections. Inflammatory destruction of bile ducts occurs in graft versus host disease, chronic hepatic allograft rejection, primary sclerosing cholangitis (PSC), and drug toxicity (vanishing bile duct syndrome). Paucity of the bile ducts may lead to chronic cholestatic liver disease with biliary-type cirrhosis.

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▪ Figure 47.3 Intrahepatic paucity of bile ducts. Portal tract with absent bile duct in a patient with Alagille syndrome.

AS is also called arteriohepatic dysplasia, and is characterized by reduced interlobular bile ducts in association with cardiac, skeletal, ocular, facial, and less frequently renal, and neurodevelopmental abnormalities (12). Features of AS are listed in Table 47.1 (12,13). The prevalence of this autosomal dominant syndrome with highly variable penetrance is reported as 1 in 100,000 live births. Histologic evidence of bile duct paucity may not be present at birth; the ducts are thought to be lost over a number of months or even years. Jaundice is present in most symptomatic patients and presents as conjugated hyperbilirubinemia (serum levels between 4 and 10 mg/dL) in the neonatal period. Hepatomegaly is invariably present and pruritus can become severe by 6 months. Xanthomas develop in patients with chronic hypercholesterolemia and can become disseminated and disfiguring (Fig. 47.4). General management includes nutritional support with provision of fat-soluble vitamin supplements and symptomatic treatment for pruritus. Some of these symptoms may be improved by partial external biliary diversion (14). In some cases, the cardiac manifestations dominate the clinical presentation, and corrective surgery for peripheral pulmonic stenosis or other lesions may be needed. Progression to liver failure and cirrhosis requiring liver transplantation occurs in approximately 15% of cases, and account for approximately 2% of pediatric liver transplantations. In other cases, the cholestasis improves as the child approaches adulthood. Vascular anomalies, such as aneurysms and coarctation of the aorta, are reported in 9% of patients, and are responsible for up to 34% of the mortality caused by this syndrome (15). The genetic defect of AS has been found on chromosome 20p12, with a deletion or mutation of a single copy of the Jagged 1 gene (16). Alterations of this gene interrupt the Notch signaling pathway that is crucial for cell-to-cell communication during differentiation. Notch signaling has an important role in the differentiation of biliary epithelial cells and is essential for their tubular formation during intrahepatic bile duct development (17).

Table 47.1. Features of Alagille Syndrome (12,13)

Feature Bile duct paucity

Percentage of patients 85–100

Chronic cholestasis

91–96

Peripheral pulmonic stenosis

67–70

Tetralogy of Fallot

9–14

Butterfly vertebrae

51–87

Characteristic facies a

95–96

Posterior embryotoxon b

78–88

Growth retardation

50–87

a

Facies consist of prominent forehead, moderate hypertelorism with deepset eyes, small pointed chin, saddle or

straight nose. b

A defect in the anterior chamber of the eye in which there is a prominence of Schwalbe's ring (this is seen in 10%

of the normal population). Data from Alagille D, Estrada A, Hadchouel M, et al. Syndromic paucity of interlobular bile ducts (Alagille syndrome or arteriohepatic dysplasia): review of 80 cases. J Pediatr 1987;110:195–200 and Emerick K, Rand EB, Goldmuntz E, et al. Features of Alagille syndrome in 92 patients: frequency and relation to prognosis. Hepatology 1999;29:822–829.

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▪ Figure 47.4 Cutaneous xanthomas. The skin of this child with Alagille syndrome has numerous xanthomas that may be plaques or nodules with characteristic smooth surface. The lesions are characteristically yellow or pink.

Genetic/Metabolic Liver Disease The liver is involved primarily or secondarily in many inborn errors of metabolism. This section will focus on those disorders that lead to acute or chronic P.1311 damage to the liver itself by one of three mechanisms: accumulation of toxic metabolites, failure to produce essential compounds, or sequestration of an abnormally synthesized product within the liver. In addition to nonspecific signs of liver disease, such as those seen in viral hepatitis or drug-induced liver injury, metabolic liver disease is often associated with other signs and symptoms that should suggest this diagnosis to the clinician (Table 47.2). Adequate liver sampling allows measurement of enzymatic pathways or substrate accumulation in addition to histologic examination. A specific diagnosis may allow effective therapy or provide an indication for liver transplantation. Genetic counseling is often indicated.

Table 47.2. Clinical Features Suggestive of Metabolic Liver Disease in Children

Coma with hyperammonemia Hypoglycemia Psychomotor retardation Hepatosplenomegaly with or without liver dysfunction Acidosis Failure to thrive Muscle weakness Coagulopathy, particularly out of proportion to liver test abnormalities Dysmorphic facial features Cholestasis Cardiac disease

Disorders of Carbohydrate Metabolism Galactosemia Galactose is normally converted to glucose through three separate enzymatic reactions involving galactokinase, galactose 1phosphate uridyl transferase (GALT), and uridine diphosphate galactose 4-epimerase. The three known disorders are now designated transferase deficiency galactosemia, epimerase deficiency galactosemia, and galactokinase deficiency galactosemia. The overall frequency is approximately 1 in 40,000 live births. The most common severe defect involves a deficiency of GALT. The sequence of the human GALT gene has been established (18). Many patients are found to be compound heterozygotes. Inactivity of the transferase results in the accumulation of toxic metabolites including galactose 1phosphate and galactitol. Early manifestations include lethargy, vomiting, acidosis, cataracts, failure to thrive, and jaundice. Urinary tract infection and/or sepsis, typically with gram-negative species, is also a common presenting problem. Hemolytic anemia and erythroid hyperplasia, occasionally severe and resembling erythroblastosis, occur in 40% of patients. Rapid recognition and treatment in the newborn period is critical because untreated disease is likely to result in severe neurologic injury. Most states have programs for newborn screening for galactosemia, but the diagnosis is confirmed with an enzymatic assay for GALT using red blood cells. Histopathologic findings in the liver include diffuse hepatocellular damage with marked steatosis, cholestasis, and pseudoacinar transformation (Fig. 47.5A,B). Treatment consists of strict elimination of galactose from the diet, which will normally reverse the hepatopathy. However, the long-term efficacy of dietary therapy may not be as successful due to difficulty in completely eliminating galactose from the diet and from endogenous conversion of glucose into galactose through reversal of the normal pathways for galactose metabolism. Long-term complications include growth failure, developmental delay, and ovarian failure despite vigilant adherence to a galactose-free diet (19).

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▪ Figure 47.5 Galactosemia. A: Pseudoacinar transformation of hepatocytes, fatty change and cholestasis is the usual triad of histologic findings. B: Oil-red-O on a frozen section reveals the extensive hepatocellular steatosis.

Hereditary fructose intolerance Hereditary fructose intolerance (HFI) is the result of a genetic deficiency in the enzyme fructose 1,6-biphosphate aldolase (aldolase B). The pathophysiologic process is due to metabolic effects of the P.1312 accumulated fructose 1-phosphate. Sorbitol is interconverted to fructose and can therefore lead to a similar process. Signs and symptoms of long-term exposure to fructose include hepatomegaly, abnormal aminotransferase values, hepatic steatosis, poor feeding, vomiting, irritability, and poor growth (20). The classic features of acute metabolic disease and hypoglycemia are not always present, because many affected individuals evolve an eating behavior that avoids fructose. Therefore, HFI needs to be considered in children with unexplained hepatomegaly and steatosis. A high index of suspicion is crucial because the presenting signs and symptoms can be subtle. The histologic findings are similar to those of galactosemia. Aldolase B activity can be measured in liver tissue. Three different specific mutations in aldolase B account for a large number of affected individuals. Deoxyribonucleic acid (DNA) diagnostic assays (including allele specific oligonucleotide hybridization) using peripheral leukocytes may be utilized. Treatment involves strict avoidance of fructose, sorbitol, and sucrose. Partial adherence to this difficult diet can ameliorate many of the acute manifestations of this disease but not the chronic problems such as growth failure.

Table 47.3. Glycogen Storage Diseases

Type

Enzyme deficiency

Tissue involved

Synonym/notes

0

Glycogen synthetase

Liver, muscle

Aglycogenosis

Ia

Glucose-6-phosphatase (G6Pase)

Liver, kidney, intestine

Von Gierke's disease (hepatorenal glycogenosis)

Ib

Translocase (T 1 ) responsible for

G6Pase activity is normal in

movement of glucose-6-phosphate

homogenate made of frozen liver but

across intracellular membranes

is deficient in isotonic homogenate made of fresh (unfrozen) liver

Ic

Translocase (T 2 , the microsomal phosphate/pyrophosphate transport protein)

Id

Translocase T 3

IIa

Lysosomal acid α-glucosidase

In the fatal, classic form (IIa),

Pompe disease

infantile

glycogen concentration excessive in

(generalized

IIb adult

all organs examined; enzyme

glycogenosis, cardiac

deficiency may be generalized;

glycogenosis)

cardiac muscle in IIb normal but deficient in α-glucosidase activity

III

Amylo-1,6-glucosidase

Liver, muscle, heart, etc., in various

Limit dextrinosis

(“debrancher” enzyme)

combinations

(debrancher glycogenosis); Cori disease; Forbes disease

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IIIa

Liver only

IIIb

Generalized

IV

Amylo-1,4→1,6-transglucosidase

Generalized (?)

(“brancher enzyme”)

Amylopectinosis (brancher glycogenosis); Andersen disease

V

Muscle phosphorylase deficiency

Skeletal muscles only

McArdle syndrome (liver and smooth muscle phosphorylase not affected)

VI

Liver phosphorylase deficiency

Liver; skeletal muscle normal

Hers disease

VII

Phosphofructokinase

Skeletal muscle, erythrocytes

Tarui disease

VIII

Hepatic phosphorylase kinase

Liver, brain, skeletal muscle normal;

Liver glycogenesis, X-

cerebral glycogen increased

linked

IX

Liver phosphorylase-b-kinase

Liver only; muscle tissue normal

deficiency

biochemically and microscopically

Glycogen storage diseases Glycogen, a polysaccharide molecule composed of D-glucose units, is found predominantly in liver and muscle. The glucose units are joined linearly by 1,4 linkages with 1,6 linkage branching at every fourth unit. The glycogen storage diseases (GSD) are disorders characterized by accumulation of glycogen in organ-specific patterns based on the deficient enzyme (Table 47.3). Clinical manifestations of the various GSDs may result from inability to utilize glycogen stores, accumulation of glycogen within the liver and/or other tissues, and the toxic effects of certain abnormal types of glycogen. Forms of GSD that primarily affect the liver produce diffuse hepatomegaly and hypoglycemia, which P.1313 may be life-threatening. Fasting hypoglycemia is the hallmark of GSD due to an inability to utilize glycogen stores to produce glucose; type I is the most common. Forms of type I GSD (Table 47.3) include deficiency of glucose 6-phosphatase (von Gierke's disease, type Ia) and various deficiencies in glucose and glucose metabolite transport (glucose 6-phosphate transport, type Ib, microsomal phosphate transport, type Ic, microsomal glucose transport, type Id). GSD type Ib presents in a clinical manner identical to GSD type I, but these patients are often neutropenic with impaired neutrophil function (21); they are prone to recurrent bacterial infection, oral and intestinal mucosal ulceration, and bleeding. The striking limitation of glucose transport across the neutrophil cell membrane may account for impairment of neutrophil function. Cytokine therapy may correct the neutropenia. A very different clinical presentation is observed in those disorders that lead to hepatic accumulation of toxic forms of glycogen. The best example of this is GSD type IV, deficiency of the glycogen branching enzyme. Glycogen that accumulates in this disease has long chains of glucose in a 1,4 linkage, resembling plant starch or amylopectin. This form of glycogen is relatively insoluble and presumed to be toxic. Liver biopsy reveals characteristic intracytoplasmic masses of periodic acidSchiff (PAS) positive, diastase resistant material that enlarge and distort hepatocytes (Fig. 47.6). Progressive liver disease therefore becomes a major distinguishing feature of GSD type IV. Portal hypertension and hepatic failure may develop in early childhood. Specific diagnosis depends on demonstration of the deficiency of enzyme activity in biopsy specimens. In these disorders, the liver biopsy should be processed for light and electron microscopic evaluation and a portion rapidly frozen for subsequent biochemical analysis. The light microscopic appearance of the liver in type I, the most common variety, demonstrates abundant accumulation of free glycogen in the cytoplasm and mild steatosis. Hepatocytes are markedly enlarged with clear cytoplasm, central nuclei, and compression of adjacent sinusoids (Fig. 47.7). Glycogenated nuclei are numerous in zone 1. Diagnosis of the specific type of GSD is critical for proper treatment and prediction of prognosis and potential complications. Specific enzymatic assays and DNA diagnostic tests are available in specialty laboratories for each of the disorders. Diagnostic assays can be performed on a number of tissues including liver, muscle, leukocytes, and fibroblasts.

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▪ Figure 47.6 Glycogenosis type IV (amylopectinosis). Large intracytoplasmic PAS+ diastase resistant inclusions enlarge and deform hepatocytes.

▪ Figure 47.7 Glycogenosis type I. Diffusely enlarged hepatocytes have clear cytoplasms that impart a plant-like appearance. Hepatocellular megamitochondria (arrows) are usually present.

GSD can present at any age, and the prognosis is highly variable. Early reports of correction of many of the metabolic derangements of GSD type I by provision of nutrients directly into the systemic circulation by total parenteral nutrition (TPN) or by portacaval shunting gave important clues to its pathogenesis and therapy. Subsequently, it was demonstrated that maintenance of blood glucose levels greater than 70 to 90 mg/dL obviated most of the clinical manifestations of GSD type I (22). The presumed mechanism of action for this therapy is reduction of the stimulus for glycogenolysis and prevention of the abnormal compensatory metabolic pathways leading to lactate accumulation, lipid synthesis, purine synthesis, and subsequent hyperuricemia. The neutropenia of GSD type Ib is not corrected by glucose homeostasis. Originally, maintenance of blood glucose was accomplished by continuous enteral feeding of infants with nasogastric or gastrostomy tubes. Alternatively, it has been shown that frequent daytime feedings (every 2 to 3 hours) of a high-starch diet can be combined with continuous nighttime tube feedings with the same effects. Frequent feeding of high-carbohydrate– containing foods and nocturnal administration of slow-release glucose polymers, such as uncooked cornstarch are utilized (22,23). This prevents the development of hypoglycemia and also P.1314 limits incorporation of excess dietary glucose into glycogen. However, as children become older, this regimen is more difficult to maintain and is altered to include daytime meals supplemented with raw cornstarch. Cornstarch undergoes slow degradation to glucose by α-amylase and, when given every 6 hours, steadily releases sufficient glucose into the system. This cornstarch supplementation can be combined with continuous nighttime feedings until the children are through the period of rapid growth and their glucose requirement decreases to the point that cornstarch supplements alone are sufficient for metabolic control. As patients with GSD type I approach late adolescence, the tendency for hypoglycemia decreases and some investigators believe that less rigorous dietary therapy is required. However, treatment of the secondary complications of the disease with agents such as allopurinol for hyperuricemia or lipid-lowering agents for the prevention of cardiovascular disease and pancreatitis may be necessary. With prolonged survival due to improved therapy, an increasing number of patients are surviving into adulthood; this has led to recognition of late complications such as altered bone mineralization, renal disease, and endocrine abnormalities (24). A long-term complication of GSD type I for which no definitive therapy has been established is hepatic adenoma (25,26). It is believed that adenomas develop because of chronic stimulation of the liver by glucagon and other trophic agents produced in response to chronic or recurrent hypoglycemia. Although some authors have reported regression of adenomas with aggressive dietary therapy, many patients who have received this treatment since infancy or early childhood are just now reaching adulthood and adenomas are a common finding in this group. Currently, a major challenge in the management of patients with GSD type I is the prevention, detection, and management of these lesions, as well as the development of a strategy for early detection of the rare transformation of adenomas into malignant lesions. In addition, a link between the hepatic adenomas and the normocytic anemia that often accompanies this disorder has been made. Hepcidin was found in abundance in the adenomas in GSD type Ia, and resection of the adenomas has resulted in normalization of the hematologic parameters and iron studies (27). Guidelines regarding monitoring of adenomas have been published, suggesting abdominal ultrasonography and measurement of serum α-fetoprotein and carcinoembryonic antigen every 3 months, as well as

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computed tomography (CT) scan or magnetic resonance imaging in the case of growth or blurring of the margins of the lesions (28). Liver transplantation has been performed in patients having GSD, with some success (29). It is important to remember that these are systemic diseases that may have variable degrees of involvement of both skeletal and cardiac muscles.

Carbohydrate-deficient glycoprotein syndromes (glycosylation disorders) The carbohydrate-deficient glycoprotein (CDG) syndromes are a group of newly recognized inborn errors of glycoprotein metabolism characterized by abnormal synthesis of N-linked oligosaccharides (30). The biochemical hallmark is a partial deficiency of the carbohydrate moiety of a wide range of secretory glycoproteins, including binding proteins, lysosomal enzymes, and coagulation factors. The clinical manifestations of the CDG syndromes, which include significant liver disease, are the direct embryologic and physiologic consequences of the abnormal N-linked glycosylation of cell structures. CDG syndrome type I is a genetic multisystem disorder (31). The clinical picture is dominated by nervous system dysfunction, resulting in psychomotor retardation, seizures, ataxia, and stroke-like episodes (due to hypercoagulability). Also noted are an abnormal pattern of subcutaneous fat distribution (lipodystrophy and inverted nipples), feeding difficulties, retinitis pigmentosa, hypoalbuminemia/protein-losing enteropathy, pericardial effusion, and/or ascites. There is an agedependent constellation of abnormalities in gonadal, thyroid and growth hormone, and insulin. Light microscopic findings in liver biopsy specimens include fibrosis and occasional cirrhosis and steatosis (32). The CDG syndrome type I is clinically and biochemically distinct from type II, which is due to a deficient activity of the Golgi enzyme N-acetylglucosaminyltransferase II, and from other CDGs. The primary defect in CDG-I is the subject of ongoing study, although phosphomannomutase (PMM) deficiency appears to be the major cause (30). Biochemical diagnosis is based on documentation of misglycosylation, usually through detection of altered isoelectric forms of serum glycoproteins. The biochemical changes are easily observed by detecting altered isoelectric focusing of serum transferrin (carbohydratedeficient transferrin). Serum antithrombin III and thyroxine-binding globulin (TBG) levels are low; these are useful screening probes for this disorder. Prenatal diagnosis is possible because PMM is active in amniocytes. No known treatment is available. Levels of intracellular mannose are limited and exogenous mannose can correct the defect in protein glycosylation in vitro; therefore some patients may benefit from including oral mannose in their regular diets.

Disorders of Lipid Metabolism Wolman's disease and cholesteryl ester storage disease Two distinct clinical syndromes, Wolman's disease and cholesterol ester storage disease (CESD), are P.1315 characterized by the massive intralysosomal accumulation of lipid (triacylglycerols and cholesteryl esters). The severe infantile-onset Wolman's disease and the milder late-onset CESD are caused by mutations in different parts of the lysosomal acid lipase gene, which is located on chromosome 10q24-q25. The diagnosis of these allelic disorders is made by demonstration of deficient lysosomal acid lipase activity in leukocytes or fibroblasts and an elevation of triglycerides and cholesterol ester levels in tissue. There is no specific therapy for these two disorders. Wolman's disease (33) is characterized clinically by steatorrhea, failure to thrive, hepatosplenomegaly, and jaundice; the disease causes death usually within the first year of life. Stippled calcification of the adrenal glands is uniformly present either early in the course or in association with terminal liver failure. The disease has been reported in several ethnic groups and appears to be inherited as an autosomal recessive trait. There is diffuse cellular accumulation of triacylglycerol and cholesterol ester in lymph nodes, bone marrow, small intestine, liver, spleen, and adrenal glands. Deficiency of lysosomal acid lipase activity directed toward the hydrolysis of either triglyceride or cholesterol ester has been demonstrated. Grossly, the liver is yellow; frozen sections show lipid droplets in the parenchymal cells, some of which contain birefringent crystals under polarized light. Routinely processed liver biopsy reveals macrovesicular and microvesicular steatosis with empty crystalline profiles. Plasma lipids are generally normal. Diagnosis depends on liver biopsy and study of frozen sections with polarized light in addition to routine staining, analysis of tissue lipid, and demonstration of acid lipase deficiency. Death has occurred in all cases despite therapeutic trials of cholestyramine, adrenal steroids, clofibrate, cyclophosphamide, antibiotics, and thyroxine. In patients with CESD, cholesteryl ester and triglyceride also accumulate in the liver and the intestinal mucosa; there is a marked decrease in lysosomal acid lipase activity against these substrates. The diagnosis can be confirmed by documenting deficiency of lysosomal acid cholesteryl hydrolase activity in fibroblasts (34). Although biochemical abnormalities are similar to those found in patients with Wolman's disease, patients with CESD have a normal life expectancy and present with hepatomegaly and hyperbetalipoproteinemia only, possibly due to a higher residual enzyme activity. Hepatomegaly is present at birth and increases with age. Grossly, the liver is similar in appearance to that in Wolman's disease, a brilliant orange-yellow color. Histologic findings on frozen section and routine light microscopy are also similar. By electron microscopy (EM), the larger vacuoles are seen to be surrounded by a single membrane, to contain angular images of cholesterol crystals, and to be secondary lysosomes. The epithelial cells of the intestinal mucosa are normal, but the lamina propria contains crystals of cholesterol ester and masses of foam cells around the lacteals. Suppression of cholesterol synthesis and apolipoprotein B production by 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors in combination with a diet excluding foods rich in cholesterol and triglycerides results in clinical improvement in some cases of CESD.

Gaucher's disease Gaucher's disease, due to deficiency of acid β-glucosidase, is associated with widespread accumulation of glucosyl-ceramide laden macrophages, resulting in hepatosplenomegaly, marrow replacement causing skeletal disease, lung infiltration, and sometimes neurologic disease. There are several types, with different ethnic and geographic patterns. Hepatomegaly is seen in more than 50% of patients, but cirrhosis and portal hypertension are uncommon. Liver histology demonstrates the glycolipid-filled macrophages (Gaucher's cells) in the sinusoids, but hepatocytes are spared (35). This is probably due to biliary excretion of the glucocerebroside and the handling of glycolipids by mononuclear phagocytes, rather than hepatocytes. The diagnosis is confirmed by measurement of acid β-glucosidase in peripheral blood leukocytes. Enzyme replacement therapy is available, but responsiveness is variable. If cirrhosis is present, response to enzyme therapy is typically poor.

Niemann-Pick disease

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The group of disorders classified under the eponym of Niemann-Pick disease (NPD) has been divided into two broad types: (a) A and B NPD are lysosomal storage disorders that result from deficient activity of acid sphingomyelinase (ASM); and (b) type C NPD is a lipidosis distinguished by a unique error in cellular trafficking of exogenous cholesterol. Both types are characterized by varying degrees of hepatomegaly, foam cells in the liver, bone marrow, and other tissues, and variably increased amounts of sphingomyelin, cholesterol, glycosphingolipids, and bis (monoacylglycero)-phosphate in the visceral organs.

Hereditary Tyrosinemia Type I Transient neonatal hypertyrosinemia is a self-limiting condition primarily of premature infants, probably caused by an immaturity in tyrosine aminotransferase activity. Hypertyrosinemia also occurs with any severe hepatic injury, usually in association with high serum methionine levels. Hereditary tyrosinemia (HT) type I is an autosomal recessive disorder caused by deficiency of fumarylacetoacetate hydrolase (FAH), the last enzyme in the tyrosine degradation pathway. The P.1316 FAH gene has been mapped to chromosome 15 at q23-q25 (36) and cloned; more than 25 mutations have been associated with the phenotype of HT. Autosomal recessive inheritance has been suggested. The worldwide incidence is approximately 1 in 100,000 births. Because of a complex founder effect, there is an unusually high prevalence (1 in 1846) of HT in the province of Quebec, Canada, particularly in the Saguenay-Lac Saint Jean region. Metabolites that accumulate proximal to the enzymatic block such as succinyl acetate, succinyl acetone, fumaryl acetoacetate, and maleylacetoacetate are highly reactive electrophilic toxic compounds, which bind to sulfhydryl groups, often leading to tissue injury. Many secondary enzymatic and biochemical defects occur in tyrosinemia because of the accumulation of these precursor compounds. For example, succinyl acetoacetate can inhibit enzymes such as porphobilinogen synthase, leading to the accumulation of 5-aminolevulinic acid and symptoms of acute intermittent porphyria. There are two forms of HT, acute and chronic, which may occur in the same family. The acute form presents in infancy with severe liver dysfunction manifested by jaundice, hepatosplenomegaly, failure to thrive, anorexia, ascites, coagulopathy, and rickets. The disorder may actually begin in utero as evidenced by the presence of well-established cirrhosis with large regenerative nodules during infancy. The chronic form presents later in childhood with cirrhosis, renal tubular dysfunction, rickets, and hepatocellular carcinoma (HCC). Episodes of severe peripheral neuropathy occur in patients surviving infancy, leading to morbidity from severe pain and even mortality from respiratory failure. Laboratory studies indicate significant compromise of hepatic synthetic function. Serum aminotransferase values are mildly to moderately elevated. Hypoglycemia is common, particularly in infants. Renal tubular dysfunction produces a Fanconi's syndrome with hyperphosphaturia, glucosuria, proteinuria, and aminoaciduria. Serum tyrosine and methionine concentrations are markedly elevated. Succinylacetone and succinylacetoacetate in the urine are typical and diagnostic of this disorder. Serum α-fetoprotein concentrations are often significantly elevated in affected infants and in cord blood, suggesting prenatal onset of liver disease. Histologic examination of the liver reveals fatty infiltration, iron deposition, varying degrees of hepatocyte necrosis, and pseudoacinar formation. Significant fibrosis may be present early in life with gradual evolution to multinodular cirrhosis, and the regenerative nodules mimic neoplasms in some patients (Fig. 47.8). HCC occurs frequently in older patients with cirrhosis. Livers of patients with HT often contain discrete nodules containing FAH activity. This mosaicism of enzymatic reactivity is due to somatic reversion to a normal genotype in these nodules. Molecular studies confirm correction of one of the disease-causing alleles in these nodules. These studies and other work in animal experiments suggest a strong selective advantage for FAH-expressing cells in an FAH-deficient liver. This information may be exploited in the future for gene therapy of HT.

▪ Figure 47.8 Hereditary tyrosinemia. In this well-established cirrhosis, the regenerative nodules show variation in size and cytology. A nodule on the left has marked steatosis, whereas in the remainder of the specimen steatosis is absent.

The acute form of HT is usually fatal in the first year of life without therapy. Treatment with a diet restricted in phenylalanine, methionine, and tyrosine does not prevent progression of the liver disease or development of HCC. Liver transplantation reverses hepatic, neurologic, and most renal manifestations of the disease. Patients with cirrhotic nodules should be considered for transplantation because of the high risk of developing carcinoma. Treatment of HT has been revolutionized by the use of a metabolic inhibitor that acts early in the tyrosine degradation pathway (inhibiting 4hydroxyphenylpyruvate dioxygenase) to prevent formation of the toxic intermediates succinyl acetoacetate (SAA) and succinyl acetone (SA). This inhibitor, (2-[2-nitro-4-trifluoromethylbenzolyl]-1,3-cyclohexanedione) NTBC, was first used in 1992 in five children with tyrosinemia. After 7 to 9 months, these patients had normal liver enzymes and coagulation studies, a decrease in α-fetoprotein levels, and no SA excretion. No toxicity was demonstrated. This report led to widespread clinical trials that largely reproduced the original experience, and more than 300 children with tyrosinemia have been treated, with subsequent stabilization of hepatic and renal function, improvement in growth and nutritional parameters, and delay or avoidance of liver transplantation. This drug has been licensed as nitisinone (trade name Orfadin). Although enthusiasm for this treatment has been somewhat tempered by the demonstration that NTBC administration corrects the hepatic and renal abnormalities in knockout mice deficient in FAH

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P.1317 activity but does not prevent all of the SA accumulation or the development of HCC, it is considered the standard of care for the treatment of HT, in addition to the dietary measures discussed in the preceding text (37). At present, the most prudent therapy for tyrosinemia is the institution of nitisinone and dietary therapy at the time of diagnosis. Close medical and radiographic monitoring is suggested for hepatic nodules that may herald early HCC, because a small percentage of children begun on therapy late in the course of disease have developed HCC despite treatment (38). Early liver transplantation is indicated in patients with severe neurologic crises.

Disorders of Bile Acid Metabolism To date, several distinct inborn errors of bile acid biosynthesis have been recognized (39); these may be primary enzyme deficiencies or disorders that arise secondary to specific organelle dysfunction such as peroxisomal disorders. At present, two distinct major treatable disorders related to defective transformation of the steroid nucleus have been described: Δ 4 -3oxosteroid 5β-reductase deficiency and 3β-hydroxy-C 2 7 -steroid dehydrogenase/isomerase deficiency. The incidence of these defects is not known. In each, primary bile acid (cholic acid) synthesis is absent or markedly impaired, and urine, serum, and bile predominantly contain atypical bile acids. The cholestasis and liver injury are attributed to failure of synthesis of adequate amounts of the normal choleretic primary bile acids that are essential for the promotion and secretion of bile and/or the increased production of unusual primitive hepatotoxic bile acid metabolites. The unusual bile acids found in patients with defects in bile acid biosynthesis might cause cholestasis by inhibiting the canalicular ATP-dependent transport system for bile acids that constitute the rate-limiting step in the overall process of bile acid transport across hepatocytes. The initial clue to the diagnosis is the finding of low serum concentrations of the primary bile acids in the presence of cholestasis. Impaired synthesis of bile salts may not be associated with either pruritus or elevated serum bile salt concentrations, because the normal end products are not synthesized. A high index of suspicion is required, because the presentation may be protean and diagnosis requires relatively specialized testing. Screening assays for these defects include gas chromatography and fast atom bombardment mass spectrometry of urine, serum, and/or bile. Confirmatory enzymatic and molecular assays exist for some of the defects. Replacement bile acid therapy has been associated with reversal of hepatic injury and normalization of liver biochemical and histologic abnormalities (40). The rationale for bile acid therapy in inborn errors of bile acid biosynthesis is to replenish the bile acid pool and downregulate endogenous bile acid synthesis, thereby decreasing the production of toxic bile acid intermediates. Ursodeoxycholic acid (UDCA) presumably displaces toxic bile acids, improves bile flow, and offers cytoprotection. Zellweger's (cerebrohepatorenal) syndrome is an example of a secondary defect in bile acid biosynthesis due to a primary defect in peroxisome development (41). Clinical manifestations include profound psychomotor retardation, hypotonia, a characteristic facies (narrow cranium, prominent forehead, hypertelorism, and epicanthic folds), cortical cysts of the kidney, and intrahepatic cholestasis. Hepatomegaly is usually present at birth and jaundice appears at 2 to 3 weeks of life. The hepatic histology includes hepatocellular damage with marked cholestasis, giant cell transformation, and pericellular fibrosis. Ultrastructurally, there is absence of peroxisomes (microbodies). Death occurs in most patients by 6 months of age. Diffuse micronodular cirrhosis is noted at autopsy. A third type of genetic defect in bile acid metabolism is that of bile acid transport defects, which will be discussed subsequently in the chapter under the section on progressive familial intrahepatic cholestasis (PFIC).

Disorders of Bilirubin Metabolism and Excretion Unconjugated hyperbilirubinemia is frequently encountered in infants. The causes are listed in Table 47.4. Normal hepatic clearance of bilirubin includes glucuronidation and carrier-mediated transport of bilirubin at the basolateral and canalicular membranes of the hepatocyte. Primary genetic abnormalities of these processes include Crigler-Najjar and Gilbert's syndromes that result from defects in glucuronidation (42) and Dubin-Johnson syndrome that results from a defect in canalicular excretion of conjugated bilirubin. Gilbert's syndrome is the most benign of these disorders and probably represents a relatively common genetic phenotype. Between 2% and 10% of individuals have Gilbert's syndrome, which is the result of an alteration in the promoter for the bilirubin uridine diphosphophate glucuronyl transferase (UDP-GT) gene. The altered promoter is transcriptionally less active and leads to a relative deficiency of the enzyme. Clinically, this translates into a condition characterized by mild indirect hyperbilirubinemia (typically 15 × 10 9 cells/L), with neutrophilia, increased erythrocyte sedimentation rate, slight anemia, and elevated alkaline phosphatase levels are common. Serum antibodies to E. histolytica are detected in more than 90% of patients. An indirect hemagglutination (IHA) with a cutoff value of 1:512 is considered diagnostic. The enzyme immunoassay (EIA) with a sensitivity of 99% and specificity greater than 90% is also commonly used. In those patients in whom an aspirate is obtained, either for diagnostic or therapeutic purposes, the material should also be sent for Gram's staining and culture (18).

▪ Figure 48.2 Liver metastases of colorectal cancer. No specific

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characteristics can differentiate it from primary neoplasia, or pyogenic or amebic liver abscess.

Imaging studies are very important in the workup of patients with suspected ALA and have reduced the delay in diagnosis. Ultrasonography is the initial screening choice. The abscess appears as an hypoechoic round or oval lesion with welldefined margins. More advanced imaging techniques such as tomography or magnetic resonance (MR) are indicated for differential diagnosis. Chest x-ray may reveal elevation of the right diaphragm, atelectasis, and pleural effusion (19).

Therapy The drug of choice is metronidazole at an oral dose of 1g twice daily for 10 to 15 days in adults and 30 to 50 mg/kg daily for 10 days divided in three doses in children; when given intravenously the dosage is 500 mg every 6 hours for adults and 7.5 mg/kg every 6 hours for children for 10 days. Other nitroimidazoles include tinidazole or ornidazole at a dose of 2 g orally daily for 10 days. Secondary drugs include chloroquine 1 g/day for 2 days orally followed by 500 mg/day for 2 to 3 weeks. In children the dose is 15 mg/kg PO daily for 2 to 5 days followed by 5 mg/kg daily for 2 weeks. Percutaneous drainage may be necessary in nonresponders to antiameba therapy to rule out a pyogenic abscess or when less than 1 cm of rim liver tissue remains around a liquefied abscess.

Vaccination Studies in experimental animals, using E. histolytica galactose-and Nacetylgalactosamine-inhibitable surface lectin either for systemic application or oral administration are ongoing. Research has focused on how to fuse surface lectin to the B subunit of cholera toxin, attenuated salmonella, or Yersinia enterocolitica for antigen delivery (20).

Pyogenic Liver Abscess Epidemiology The incidence of PLA is 0.007% to 2.2% of hospital admissions, 11 per 1 million in general population, and between 0.29% and 1.47% in autopsy series. PLA varies among different geographic regions influenced by the local prevalence of bacterial, parasitic, and helmintic infections, age of the population, and the presence of chronic debilitating diseases. Benign or malignant biliary tract disease, diverticulitis, and Crohn′s disease are the most common predisposing factors. The frequency of PLA has increased as a complication of more aggressive treatment of liver P.1354 or pancreatic malignancies—stent placement, sphincterotomy, embolization, ethanol injection, or radiofrequency ablation. In the past, PLA was primarily a complication of ruptured appendix (21). Accordingly, the age of presentation has moved forward from the second and third decades of life to the sixth and seventh (21,22). Advances in imaging techniques and new antibiotics, have decreased the morbidity and mortality of PLA (22,23).

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Pathogenesis Abscess formation, a host defense strategy to contain the spread of infection, is promoted by a combination of factors that impair phagocytosis and the clearance of microorganisms. Neutrophils and platelets attached to the endothelial surface, and endotoxin produced by gram-negative bacteria contribute to tissue injury by releasing proinflammatory cytokines and reactive oxygen species. When bacteria reach the liver, endotoxin stimulates the proliferation of Kupffer cells that engorge, and produce toxic mediators that modulate microvascular response. After adhesion, diapedesis through cell junctions follows. The inflammation thus produced causes obstruction of the sinusoidal lumen and secondary obstruction of the blood flow. These phenomena inhibit sodium and potassium ATP activity, impair the generation of energy for bile excretion, and promote biliary stasis. The sinusoidal diameter is reduced and hence the velocity of the blood flow decreases; as the number of obstructed sinusoids increases and hydrostatic pressure rises, hepatic ischemia develops (24). The source of infection determines to a certain degree the localization and number of abscesses. If infection reaches the liver through the portal system, several abscesses may develop, mostly confined to the right lobe. The left lobe is usually involved in septic thrombosis of the portal vein. When bacteria reach the liver through arterial circulation, several small abscesses develop, equally distributed in both lobes. Forty percent of patients with PLA have multiple liver abscesses (25,26).

Clinical Manifestations An early clinical diagnosis requires a high index of suspicion: Fever, malaise, right upper quadrant abdominal pain, nausea, and vomiting for more than 2 weeks are the most common presentations (21,27). Abdominal pain in patients with PLA is similar to that found in patients with ALA (25). Other symptoms, anorexia, jaundice, and painful hepatomegaly are less prevalent in PLA as compared to ALA (26,28,29,30). Jaundice predicts a complicated clinical course but has no impact on mortality. Approximately 60% have an underlying debilitating condition or have had a recent interventional procedure (e.g., biliary stent placement, ethanol injection). PLA should be suspected in elderly patients, in those taking steroids, or in patients with right-sided pulmonary abnormalities of unknown origin (30,31).

Diagnosis When PLA is diagnosed, prognostic factors associated with increased mortality include low albumin, anemia, high blood urea nitrogen (BUN) and creatinine, prolonged prothrombin time, polymicrobial infection, pleural effusion, high acute physiological assessment and chronic health evaluation (APACHE) II score, disseminated intravascular coagulation, and septic shock. Multiple abscesses carry a high mortality risk independent of other risk factors (23). Regarding PLA in patients with cancer, morphology and topography are not different from noncancer patients (25).

Distinguishing Characteristics Distinguishing PLA from ALA is crucial because treatment and prognosis are different. Detection of PLA relies on laboratory and imaging findings (Table 48.1). Abdominal ultrasonography and computed tomography (CT) scan have

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sensitivities greater than 95% in detecting abscess formation (23,27). PLA and ALA have similar imaging characteristics (Figure 48.3) (28). Patients with PLA are older than those with ALA, and more likely to have debilitating diseases; this might explain the lower concentration of albumin found in patients with PLA. Abnormal chest findings are more prevalent in patients with PLA (28).

Table 48.1. Diagnostic Differences Between Amebic Liver Abscess and Pyogenic Liver Abscess

Amebic liver abscess

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Pyogenic liver abscess

Leukocytosis >15 × 10 9

Leukocytosis >15 × 10 9

Serum antibodies to E. histolytica

Serum antibodies to E.

>1:512

histolytica negative

Aspirated pus shows no microorganisms

Aspirated pus shows bacteria

Jaundice uncommon ( Table of Contents > Volume 2 > Section XI - Infectious and Granulomatous Disease > Chapter 49 - Parasitic Diseases

Chapter 49 Parasitic Diseases Michael A. Dunn

Key Concepts z

Liver parasites span a wide range of complexity, from intracellular protozoa to visible multicellular helminths with highly evolved life cycles. Different species mature and reproduce within hepatocytes, reticuloendothelial cells, the portal venous system, and the bile ducts.

z

Well-adapted parasites cause minimal acute injury to the host organ as they generate enormous numbers of progeny that pass into the blood or bile with the potential to infect other hosts. Examples include the malaria parasites, the schistosome worms, and the bile duct flukes.

z

When a parasite enters a species or an organ to which it is poorly adapted, acute or severe injury is likely: Echinococcus tapeworms, well adapted to canine-herbivore or canine-rodent life cycles, cause severe cystic liver disease in accidental human hosts. The protozoan Entamoeba histolytica and the roundworm Ascaris, both well suited to the human intestinal lumen, cause acute injury when they invade the liver parenchyma or bile ducts, respectively.

z

Successful parasites have evolved to evade or to accommodate the effects of the defenses and immunologic responses of healthy hosts. Hosts with abnormal or compromised responses are at risk for severe disease manifestations, such as the reactivation of subclinical Leishmania infection with development of advanced visceral leishmaniasis in human immunodeficiency virus (HIV)infected persons.

Protozoal Diseases Malaria, one of the world's most serious and widespread infectious diseases, is intimately involved with the liver during its pre-erythrocytic and exoerythrocytic stages of development. Visceral leishmaniasis is a cause of severe debility and hepatosplenomegaly in the tropics and a growing concern for immunosuppressed persons in temperate climates. In addition to these obligatory intracellular parasites, Entamoeba histolytica, an extracellular protozoan cause of liver abscess, is considered in Chapter 48.

Malaria Malaria, the world's most prevalent fatal parasitic disease, is caused in humans by intracellular protozoa of four species, Plasmodium falciparum, Plasmodium vivax, Plasmodium ovale, and Plasmodium malariae. All are transmitted by mosquito bite, and involve the entry of mosquito-borne sporozoites into hepatocytes, where a pre-

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erythrocytic stage of the parasite multiplies and is subsequently released to invade erythrocytes. Malaria continues to kill 2 million persons a year and frustrate eradication efforts because of the parasite's capacity to develop drug resistance. There is, therefore, great interest in defining the events within the liver that may account for complete protection of animals with a vaccine directed against genetically attenuated sporozoites (1). Protection of immunized animals appears to depend both on antibody-mediated recognition of a sporozoite surface protein that binds to liver extracellular matrix proteoglycans, and cell-mediated responses to attenuated P.1360 parasites that enter hepatocytes but fail to multiply (2).

▪ Figure 49.1 Visceral leishmaniasis. Dot-like organisms (arrow) are present in several hypertrophied Kupffer cells (hematoxylin-eosin, ×1,000). (Armed Forces Institute of Pathology [AFIP] Negative 87-5647.)

The cyclical fevers, hemolysis, vascular stasis, shock, and multiple organ failure of severe malaria are the clinical end results of synchronized multiplication and release of the parasite's erythrocytic stage. Kupffer cells take up released hemoglobin degradation products known as malarial pigment, which appears as dark cytoplasmic granules in liver specimens from persons with a history of malaria. Humans with intact host defenses normally recover from acute episodes of malaria. The highest risk for severe illness and death is with P. falciparum infection. Falciparum malaria often produces clinical and laboratory evidence of multiple organ dysfunction. In two reviews, 60% of 106 patients (3) and 20% of 91 patients (4) showed modest

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elevations in serum bilirubin, aspartate aminotransferase, or alkaline phosphatase levels. Severe liver injury in malaria has only infrequently been reported in patients with heavy P. falciparum infections, commonly associated with acute renal failure and encephalopathy. In a report from India, seven such patients presented with the acute onset of jaundice, asterixis or impaired sensorium, bleeding with prolonged prothrombin and partial thromboplastin times, and aminotransferase elevations at fourfold the normal (5). P. falciparum infection was evident in their blood smears. The three survivors responded to intravenous quinine and supportive care that included lactulose and bowel cleansing. One of the four patients who died had submassive hepatic necrosis; focal steatonecrosis was present in postmortem liver specimens from the other three. As with earlier similar reports, it is unclear to what extent liver injury contributed to morbidity in these patients. The key message remains, however, that a clinical presentation suggesting acute hepatic failure in persons at risk for malaria infection should prompt consideration of this readily diagnosed and treatable illness.

Leishmaniasis Visceral leishmaniasis, or kala-azar, is an infection of the reticuloendothelial cells of the liver, spleen, bone marrow, and other organs with an intracellular protozoan parasite, Leishmania. Common throughout the tropics, visceral leishmaniasis has been increasingly recognized elsewhere as a potential problem for immunosuppressed persons with human immunodeficiency virus (HIV) disease or after organ transplantation (6). As an experimental disease model, leishmanial infection provides an opportunity to study liver inflammation and fibrosis with the same methods that have advanced our knowledge of these important processes in other diseases, such as hepatic schistosomiasis. Infections with different species of Leishmania cause visceral, cutaneous, and mucocutaneous patterns of disease. Visceral leishmaniasis, involving the liver, normally results from infection of children and young adults with Leishmania donovani. In the Indian subcontinent, the parasite is transmitted by sandflies that have bitten infected humans. Elsewhere—in South America, southern Europe, Africa, the Middle East, and China—L. donovani transmission to humans by sandflies is primarily enzootic, involving canine and rodent reservoir hosts. Visceral involvement with Leishmania tropica, a species that normally causes cutaneous disease, was described in eight American veterans of the 1991 Persian Gulf War (7), and two more recent cases of visceral disease due to L. donovani were reported in American soldiers exposed to infection in Afghanistan (8). Other than infection from the bite of sandflies in endemic areas, clinical studies suggest that Leishmania can be transmitted by blood transfusion or needles shared for drug abuse, by sexual contact, or by transplantation of infected organs (9,10,11,12). After bloodstream infection and uptake of the parasite by reticuloendothelial cells, its amastygote stage, shown in Figure 49.1, multiplies within Kupffer cells and macrophages, infects new cells, and triggers cellular and humoral host responses. Most immunocompetent persons respond to infection with a successful T helper cell 1 (Th) 1-type cell-mediated defense that prevents clinical disease and suppresses, but may not P.1361 eliminate, the infection (13). Such a cellular response, akin to that seen in tuberculoid leprosy or successfully contained initial Mycobacterium tuberculosis infection, involves the same T4 cells and cytokines—interferon-γ, interleukin (IL)-2, and IL-12—that are critical for dealing with other intracellular organisms. The potential importance of inducible synthesis of nitric oxide as an effective mechanism for Th 1–mediated killing of the parasite was suggested by a report of high

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susceptibility of Syrian hamsters, which are deficient in nitric oxide generation, to severe visceral disease after L. donovani infection, despite their ability to mount a prominent and otherwise complete Th 1 cytokine response (14). Humoral antibody responses, also regularly present, do not appear to modify the course of leishmanial infection, nor do the Th 2–type cellular responses seen in persons who develop clinically severe disease. Pathologic examination of liver specimens shows findings that parallel the predominant host response: In persons with minimal disease and few parasites visible in liver specimens, epithelioid granulomas, including fibrin-ring granulomas similar to those described in Q fever, may be present (15). Numerous parasites multiplying within activated Kupffer cells and macrophages, appearance of myofibroblasts, deposition of intralobular collagen, and effacement of the space of Disse with connective tissue all accompany an ineffective response in persons with overt disease (16,17). A pattern of severe intralobular liver fibrosis as a predominant finding was described by Rogers (18) in 1908 as a “peculiar cirrhosis” in Indian patients with visceral leishmaniasis. So-called Rogers' cirrhosis, however, shows normal liver architecture and no regenerative nodules. The major clinical manifestations of visceral leishmaniasis include fever, weight loss, hepatomegaly, splenomegaly, lymphadenopathy, pancytopenia, and hypergammaglobulinemia. All organs with reticuloendothelial cells may be involved, including the entire gastrointestinal tract. Laboratory abnormalities may include modest elevations in serum aminotransferase and alkaline phosphatase levels and depressed albumin levels, as well as skin test anergy to common delayed hypersensitivity antigens. Although hepatic and splenic enlargement from cellular infiltration may be truly massive and intralobular liver fibrosis may be pronounced, overt ascites is uncommon, and the very rare occurrence of either hepatocellular failure (19) or of clinically evident portal hypertension suggests another etiology. Persons with advanced disease are at risk of death from intercurrent infections or severe malnutrition. Conversely, malnutrition, immunosuppressive therapy, or an immunosuppressive disease such as HIV infection can precipitate the development of overt visceral leishmaniasis in previously healthy persons with latent infections acquired as long as 20 years earlier (20,21). Severe HIV-associated visceral leishmaniasis has been described in reports from Spain, a Leishmania endemic area, as well as from nonendemic countries such as France and Germany (11,21,22,23). Visceral leishmaniasis should be sought as a treatable cause of fever, hepatosplenomegaly, and rapid deterioration in HIVinfected persons with even a remote positive travel history or risk factors for non– sandfly-transmitted blood-borne infection. Intracellular parasites may be seen in liver or intestinal biopsy specimens obtained during the evaluation of HIV-infected persons for persistent fever or diarrhea (24). Most such patients have CD4 cell counts less than 400/mm 3 , consistent with the importance of an intact Th 1 cellular response for dealing with leishmanial infection. This relationship supports the suggestion that visceral leishmaniasis in HIV-infected persons should be considered as an acquired immunodeficiency syndrome (AIDS)-defining illness (11,23). Most HIV-positive patients with visceral leishmaniasis respond well to antimonial therapy; however, relapse after cessation of treatment is common, so that long-term suppressive therapy with fluconazole, ketoconazole, or pentamidine is often used (23). Visceral leishmaniasis may also become manifest in immunosuppressed liver, heart and kidney transplant recipients (12,25); in one report, the donor liver was considered the likely source of parasite infection (12). Reduction of the immunosuppressive regimen to the minimum needed to support graft function, combined with initial antimonial and long-term suppressive antiparasitic therapy, is

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the recommended management. The diagnostic procedure for visceral leishmaniasis with the highest accuracy, close to 100%, is the examination and culture of a needle splenic aspirate. In nonendemic areas where the experience levels to safely perform splenic aspiration are lacking, examination and culture of bone marrow and liver biopsy specimens are more often performed. Either method provides a 50% to 80% yield. Polymerase chain reaction– based detection of leishmanial DNA in peripheral blood has now been reported to match the diagnostic accuracy of bone marrow aspiration (26,27). The mainstays of therapy for visceral leishmaniasis are pentavalent antimonial compounds; in the United States, the Centers for Disease Control drug service provides sodium stibogluconate as an investigational drug. Its use by daily intramuscular or intravenous administration for 3 weeks or longer is safe and generally effective. Second-line antileishmanials include pentamidine, amphotericin B, allopurinol, and ketoconazole and related azole compounds. A new drug-delivery strategy of incorporating amphotericin B into liposomes or lipid complexes appears to greatly enhance its efficacy: 5-day courses of lipid-complexed amphotericin B at total doses of 5 to 15 mg/kg were P.1362 remarkably effective in patients who had not responded or relapsed after antimonial therapy (28). Although the clinical manifestations of visceral leishmaniasis resolve with antiparasitic therapy, it remains unclear, especially in persons with underlying immunologic deficits, whether the infection is ever truly eliminated or only suppressed below detectable limits (29). The successful use of highly active antiretroviral therapy (HAART) in HIV-infected patients, for example, is thought to be responsible for recent major decreases in the incidence of clinically overt visceral leishmaniasis in France and Spain, although HIV-infected persons with inapparent leishmanial infection remain at lifelong risk for the occurrence of clinical illness (30,31). Visceral leishmaniasis has attracted investigative interest because of its association with severe intralobular liver fibrosis, which appears to be fully reversible after treatment of the infection (16). When experimental animal systems for the study of liver fibrosis in visceral leishmaniasis are defined, we may gain information of comparable significance to that which has already been gained for the cellular inflammatory immunopathology of this disease.

Helminthic Liver Diseases Schistosomes are blood flukes that are well adapted to long survival as male and female adults in the venous circulations of human hosts. Human disease involves host responses to the deposition of schistosome eggs in tissues. Fascioliasis is caused by flukes that primarily infect sheep and other herbivores. When humans are infected, a biphasic liver disease results from maturation of the parasite as it migrates through the liver parenchyma followed by an extended life span in the bile ducts. Clonorchiasis and opisthorchiasis are biliary infections by trematode flukes that are well adapted to humans. Asymptomatic or minimally symptomatic for many years in most infected persons, these infections are of major concern because of their potential for the development of cholangiocarcinoma.

Table 49.1. Imaging Characteristics in Helminthic Liver Diseases

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Imaging Infection

methods

Schistosomiasis

Ultrasonography

Findings Portal fibrosis

Reversibility Years to permanent

Fascioliasis,

Computed

Serpiginous linear

acute

tomography

subcapsular

Months

abscess tracts

Fascioliasis,

Ultrasonography,

Dilated ducts,

Months to

chronic

computed

visible adult worms

years

tomography, cholangiography

Clonorchiasis

Ultrasonography,

Dilated irregular

Years to

and

computed

ducts, stones,

permanent

opisthorchiasis

tomography,

associated

cholangiography

cholangiocarcinoma

Cystic and

Ultrasonography,

Cysts with variable

Years to

alveolar

computed

wall calcification,

permanent

echinococcosis

tomography,

complex internal

magnetic

structures, and

resonance

daughter cysts

imaging

Ascariasis

Ultrasonography,

Dilated ducts

computed

obstructed by

tomography,

worms

Months

cholangiography

Echinococcosis is a potentially life-threatening cystic liver disease caused by the infection of humans as accidental intermediate hosts of three species of canine cestode tapeworms. A relatively uncommon complication of intestinal infection with the nematode roundworm Ascaris lumbricoides is biliary ascariasis, which manifests as biliary colic, cholangitis, or pancreatitis induced by the migration of one or more of these large (up to 20 cm) adult worms into the ductal system (32,33,34). Biliary ascariasis usually occurs in children or in adults with an abnormal, open ampullary orifice produced by preexisting biliary tract disease or after surgical or endoscopic sphincterotomy (35). Ascaris worms in the ductal system are readily visualized on ultrasonography or computed tomography. If the worms do not spontaneously clear from the duct after antihelminthic treatment with mebendazole or an alternative agent, they may be removed endoscopically (32,35). Chronic biliary ascariasis has been implicated in the development of Oriental cholangiohepatitis, as discussed later for clonorchiasis and opisthorchiasis.

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Abdominal imaging methods may show characteristic findings in helminthic liver diseases, as summarized in Table 49.1. The laboratory diagnosis of helminthic infections, as shown in Table 49.2, relies primarily on demonstrating eggs in the stool when the parasite's life cycle involves egg excretion by the human host. Serologic examinations, especially enzyme-linked immunosorbent assay (ELISA) methods, have become established for most infections as diagnostic adjuncts; serologic diagnosis is especially helpful when positive in the acute stage of fascioliasis and in echinococcosis, situations in which fecal egg excretion does not take place. Eosinophilia is such a regular accompaniment of most helminthic infections that its occurrence should prompt their diagnostic consideration, and its persistence after presumed parasitologic cure may signal treatment failure.

Table 49.2. Diagnosis of Helminthic Liver Diseases

Stool examination for Infection Schistosomiasis

Serology

eggs Method of choice in

ELISA available

active infection, may be supplemented with rectal mucosal biopsy

Fascioliasis,

Negative

acute

ELISA highly sensitive and specific, serial testing useful to monitor response to therapy

Fascioliasis,

Often positive but egg

ELISA method useful in

chronic

production may be

addition to stool

intermittent

examination

Clonorchiasis,

Method of choice in

ELISA available; limited

opisthorchiasis

active infection, stool

utility

PCR may be useful in mass screening

Echinococcosis

Negative

IHA or ELISA positive in 90% of cases, serial testing useful to monitor response to therapy

Ascariasis

Method of choice

Not applicable

ELISA, enzyme-linked immunosorbent assay; PCR, polymerase chain reaction; IHA, indirect hemagglutination assay.

P.1363

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Schistosomiasis Schistosomes are trematode flukes, which infect more than 200 million persons worldwide. Schistosomiasis has attracted more study and effort than all the other parasitic liver diseases combined. Few other diseases of any cause have posed the intensity and breadth of challenges in molecular biology, immunology, economic development, pharmacology, and surgical therapy that have been overcome and that remain for this disease (36).

Disease mechanisms Schistosomes begin their life cycles with the passage of eggs by adult females that live, paired with male worms, in the mesenteric or vesical venous beds. Viable eggs erode through the intestinal or bladder mucosa, are passed in feces or urine, hatch in water, and infect an intermediate snail host. Snails shed free-swimming ceracariae, the infectious stage for humans, which have the ability to penetrate human skin and transform into immature worms. The worms mature over a period of approximately 6 weeks as they traverse the venous, pulmonary, and systemic circulations and localize in their species-specific target vessels to form male–female copulating adult worm pairs and initiate egg production that may continue for decades (37). Five species of schistosomes, listed in Table 49.3, develop to maturity in humans. The great majority of schistosomal liver disease is caused by infections with Schistosoma mansoni in Africa and South America and Schistosoma japonicum in Asia. Although portal-tract egg deposition, granuloma formation, and fibrosis have been reported in persons infected with Schistosoma hematobium (38), these findings are minor compared with urinary tract egg deposition and disease. Schistosoma mekongi and Schistosoma intercalatum have limited geographic distributions in Asia and Africa, respectively.

Table 49.3. Human Schistosomes

Species

Geographic range

Schistosoma

Middle East,

mansoni

Africa, Central

Preferred

Main target

vascular bed

organs

Mesenteric

Liver, colon

Mesenteric

Liver, small

and South America

Schistosoma

Far East

japonicum

intestine, colon

Schistosoma

Middle East,

hematobium

Africa

Schistosoma

Southeast Asia

Vesical

Bladder, ureters

Mesenteric

Liver, small

mekongi

Schistosoma

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intestine, colon

Central Africa

Mesenteric

Colon, less

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intercalatum

severe liver and small intestinal disease

The preferential homing and predilection of maturing schistosomes of all species other than S. hematobium to concentrate in the mesenteric venous system, and of the latter species to concentrate in the vesical plexus, is central to the pattern of subsequent injury that their infections produce. Immature worms make several passes through the circulation before remaining at their preferred location (39). The mechanism that signals this remarkable preference for specific vascular beds is unknown. One potential localizing signal was suggested by the finding that human portal serum, but not peripheral blood, contains material of molecular weight greater than 1,000 that stimulates cell proliferation in immature S. mansoni worms (40). Mature worm pairs in the mesenteric veins continuously produce large numbers of viable eggs that are carried to the intestine or the liver. Eggs deposited in the vessels of the intestinal mucosa may remain trapped within inflammatory granulomas, or erode into the P.1364 lumen and be excreted. Liver disease in schistosomiasis results from the entrapment of eggs that lodge in portal venules (41). Eggs in the liver remain viable for approximately 3 weeks and secrete products that elicit a characteristic initial response, the schistosome egg granuloma, as shown in Figure 49.2A. In some persons with heavy infections, the end result of hepatic schistosomiasis is severe portal fibrosis, as shown in Figure 49.2B. Advanced schistosomal hepatic fibrosis gives a gross appearance of greatly enlarged fibrotic portal tracts, described by Symmers (42) in 1904 as resembling clay pipestems thrust through the liver, and now termed Symmers' pipestem fibrosis.

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▪ Figure 49.2 A: A Schistosoma mansoni egg granuloma in the liver. The schistosome egg has lodged in a portal venule, with formation of an epithelioid granuloma (hematoxylin-eosin, ×250). (AFIP Negative 79-16805.) B: Hepatic schistosomiasis. The large area of scarring would correspond grossly to pipestem portal fibrosis. A Schistosoma mansoni egg granuloma is at the lower right margin of the field (hematoxylin-eosin, ×60). (AFIP Negative 79-16808.)

Schistosomiasis has become a valuable model disease, in both clinical and experimental animal studies, for advancing our understanding of the key processes of hepatic inflammation and fibrosis (43,44,45). Important control points and mechanisms of immune regulation and collagen gene expression are more clearly defined in schistosomiasis than in other chronic liver diseases. The antigenic products secreted by living schistosome eggs first elicit a predominant Th 1–type cellular response, marked by an influx of mononuclear cells and formation of highly cellular egg granulomas, with initiation of increased collagen formation. Over time, from several weeks to months depending on the specific experimental model or human infection, a modulation of the initial cellular reaction takes place as egg deposition continues, with a diminution of the intensity of inflammation and a shift to a predominantly Th 2–type cellular response with prominent eosinophilic infiltration of granulomas and continuing deposition of fibrous tissue. Of the mediators associated with the Th 2 response, IL-13 appears to have strong potential as a pivotal mediator of fibrogenesis, based on studies in S. mansoni infected gene knockout mice that fail to express either IL-13 or its receptor complex (45). In humans, there appears to be a genetic component of susceptibility of infected persons to severe fibrotic disease. One report suggested an association between schistosomal hepatosplenomegaly and human leukocyte antigen (HLA) alleles A1 and B5 (46). In another study, a codominant gene with an allele frequency of 0.16 in a heavily infected community in Sudan was associated with severe schistosomal hepatic fibrosis. The gene, located on chromosome 6, was closely linked to the interferon-γ receptor gene (47). In general, however, the most important single determinant of the severity of disease in hepatic schistosomiasis appears to be the intensity of egg deposition in the liver over time (37).

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Hepatic fibrosis Synthesis, deposition, remodeling, and turnover of collagen types I and III and basement membrane–associated collagen components, as well as that of fibronectin P.1365 and accompanying matrix substances such as glycosaminoglycans, are greatly increased in hepatic schistosomiasis, as are the plasma levels of multiple markers of collagen deposition. Experimental schistosomiasis has been an especially useful model for the study of the specific inflammatory cytokines proposed to have an influence on fibrogenesis (45). In schistosomiasis, cells in granulomas and in adjacent fibrotic portal tracts show the appearance of stellate cells known to produce collagen and other connective tissue components in other chronic liver diseases. The potential interactions between granuloma macrophages, cytokines, and stellate cells appear to parallel those described in other experimental model systems (48). As disease progresses from initial egg deposition to advanced fibrosis, portal tracts become less prominently involved with inflammatory cells, and prominent cellular infiltrates diminish and disappear. Portal tracts in persons with Symmers fibrosis are markedly expanded with broad, dense-appearing bands of relatively acellular, mature fibrous tissue, as shown in Figure 49.2B. Because normal liver architecture is preserved in hepatic schistosomiasis, reversal of portal-tract inflammation and fibrosis should allow resolution of the disease and restoration of normal function. Reversal of fibrosis has been well described after the cure of early S. mansoni and S. japonicum infections in mice (49,50). Murine schistosomiasis is one of the best-studied examples of the increased activity of two competing processes, collagen biosynthesis versus collagenolysis, in inflammatory fibrotic liver disease (51,52,53). In this model system, cure of infection with cessation of new egg deposition in the liver appears to allow collagenolysis to predominate over continued collagen synthesis, with resolution of fibrosis. It is unclear, however, to what extent the advanced dense portal collagen deposition associated with chronic human hepatic fibrosis might be subject to the same outcome. Two lines of evidence suggest that even dense pipestem fibrosis may be reversible, at least in part. First, rabbits infected with S. japonicum provide an animal model of dense portal collagen deposition that resembles human pipestem fibrosis morphologically and biochemically and shows slow reversibility of fibrosis over a 40-week period after cure of the infection (54). Second, serial ultrasonographic examination of persons with schistosome infection has become a standard method of assessing pipestem hepatic fibrosis in population-based treatment studies (55,56,57,58). The ultrasonographic appearance of pipestem fibrosis is shown in Figure 49.3. Ultrasonography in persons with acute nonfibrotic liver diseases may show a modest degree of portal-tract expansion that cannot be distinguished from early schistosomal fibrosis (59), and the imaging method is not reliable for assessing fibrosis in persons with schistosomiasis and coexisting conditions such as chronic viral hepatitis (60). Taking these precautions into account, multiple reports now clearly document the partial or complete resolution over several years of the ultrasonographic findings of pipestem fibrosis after parasitologic cure of S. mansoni or S. japonicum infection (61,62,63,64,65). In children and in adults treated after relatively short durations of infection, ultrasonographic resolution is more likely to be complete and accompanied by reversal of hepatomegaly and splenomegaly as assessed on physical examination.

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▪ Figure 49.3 Hepatic schistosomiasis. Ultrasonography shows echogenic deposits of pipestem portal fibrosis at arrowheads. (Courtesy of Colonel Michael P. Brazaitis, Department of Radiology, Walter Reed Army Medical Center.)

Clinical manifestations The cercariae of all schistosomes, including those that die on skin penetration in humans, such as the avian schistosome species, may cause a hypersensitivity dermatitis, swimmer's itch. A potentially fatal acute illness, Katayama fever, is a serum sickness–like syndrome triggered by the onset of tissue egg deposition in heavy infections (36). The cardinal characteristic manifestations of advanced hepatic schistosomiasis are related to portal fibrosis and the development of presinusoidal portal hypertension, with passive congestion of the portal system, hepatomegaly, potentially marked splenomegaly, and the enlargement of collateral vessels such as esophageal and gastric varices. Patients classically present with a history of one multiple variceal bleeding episode, accompanied by prominent splenomegaly, no ascites, and normal or nearly normal indices of synthetic liver function and other biochemical laboratory values. It has become increasingly evident from careful longitudinal study of the populations of endemic areas, however, that the greatest health and economic impact of chronic schistosomiasis may P.1366 not be its dramatic end state with variceal bleeding, but retardation of growth and development, malnutrition, and generalized debility in heavily infected children and adults (66,67). Growth retardation in children with schistosomiasis is specifically associated with the infection rather than other potential causes and is only partially overcome after parasitologic cure (66). The prominent splenomegaly of persons with hepatic schistosomiasis is caused both by infiltration with inflammatory cells and by passive congestion. The spleen is firm, normally nontender on palpation, and may be the site of sufficient sequestration to produce clinically important reductions in red blood cells, leukocytes, and platelets, as well as significant discomfort attributed to the bulk of the enlarged organ. Symptomatic splenomegaly may persist after the cure of infection, so that simple splenectomy is one of the most common surgical procedures in endemic areas. Segmental splenectomy, with removal of the bulk of an enlarged organ and preservation of a functional remnant of approximately normal size, is safe and

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effective in experienced hands when hypersplenism in schistosomiasis requires surgical therapy (68). When variceal bleeding is an additional concern, portal variceal disconnection may be added (69), although as discussed in the subsequent text, optimal therapy to prevent recurrent variceal bleeding in schistosomiasis is far from clear. Massive splenomegaly may suggest the presence of follicular lymphoma of the spleen, the only malignant tumor clearly associated with hepatic schistosomiasis. Follicular lymphoma was reported to occur in 1% of S. mansoni– infected Brazilian patients who required splenectomy (70). Bacterial infections associated with schistosomiasis include pyogenic liver abscesses, predominantly caused by Staphylococcus aureus (71) and chronic Salmonella bacteremia (72). Liver abscesses tend to occur in persons with early schistosome infections, perhaps coincident with the effects of initial egg deposition and the initial formation of highly cellular and vascular egg granulomas, as noted in the preceding text. Chronic Salmonella bacteremia appears related to the sequestration of living bacteria in the integument of adult worms and may be permanently cured only after elimination of the parasitic infection. HIV and schistosome infections now coexist in a growing number of persons as the HIV epidemic spreads through areas endemic for schistosomiasis. No clear-cut clinical interaction of these diseases, with their profound cellular immunologic disturbances, has been reported so far in persons with both infections (73).

Schistosomiasis and viral hepatitis The accepted clinical findings of hepatic schistosomiasis—normal liver architecture and cellular function in the presence of portal fibrosis and portal hypertension—are present only in a minority of schistosome-infected persons who require hospitalization for liver disease. Because testing for the markers of hepatitis B and C infections has become widespread, it is evident that regions with a high prevalence of S. mansoni and S. japonicum infections also tend to have high endemicity for chronic viral hepatitis (74,75,76,77). In most populations studied, there is no higher occurrence of coinfection with schistosomiasis and hepatitis B or C than would be expected by their independent prevalence (78,79). An increased risk for acquiring both infections has been reported, however, in persons with schistosomiasis who required transfusions, and a major increase in the risk for hepatitis C infection has now become evident as the unintended consequence of mass treatment programs for schistosomiasis prior to 1980 that used injections with inadequately sterilized nondisposable syringes and needles (80). For example, in communities in Egypt with an overall prevalence of anti-hepatitis C virus (HCV) of 15% to 20%, up to 50% of persons in age groups with a history of such mass parenteral therapy are now antiHCV positive (81). The intensive viral transmission attributed to these mass parenteral treatment programs, with formation of a large reservoir of chronic HCV infection, is thought to be responsible for the high current prevalence and transmission rates of hepatitis C in these areas (81). In persons who develop both hepatic schistosomiasis and chronic viral hepatitis, severe illness is common. Most of the subset of persons living in schistosomiasis endemic areas who are hospitalized for variceal bleeding, management of ascites, or decompensated hepatocellular failure do, in fact, have both schistosomiasis and chronic viral hepatitis, frequently with cirrhosis (74,75,82,83). Whether comorbidity involves specific interactions of the pathologic mechanisms of both diseases or is simply a summation of their effects is unclear. Two comparisons of the extent of pathologic findings of chronic hepatitis C in liver biopsy specimens from persons with and without schistosomiasis suggested more severe histologic activity of chronic hepatitis in dually infected persons in one report (84), but not in the other (85). When acute hepatitis C infection occurred in health care providers with preexisting

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chronic S. mansoni infection, they showed uniform inability to clear viremia and accelerated histologic progression of chronic hepatitis C compared with the course of hepatitis C infection in their colleagues without schistosome infection (86). Persons with coexisting S. mansoni infection and chronic hepatitis C appear less likely than others to respond to interferon therapy (87,88) and S. mansoni–infected persons respond less consistently to hepatitis B vaccination (89,90), although vaccination should be a high priority in schistosome-endemic areas to prevent as P.1367 much comorbidity as possible. Antiviral therapy for chronic hepatitis B or C should be considered for persons who have been cured of active schistosome infection and who would otherwise meet treatment criteria, bearing in mind that the predominant HCV genotype transmitted in Egypt is type 4 (88).

Diagnosis Detection of schistosome eggs in the stool is the most useful diagnostic method for documenting active infection. Quantitative studies have shown generally strong relationships between the extent of fecal egg output, the host's worm burden, and the extent of pathology in both S. mansoni and S. japonicum infections (37,41). Stool examinations for eggs become negative after parasitologic cure of infection. Some persons with active untreated S. japonicum infections causing significant morbidity may also show few or no eggs on stool examination (66). Low-power examination of fresh rectal mucosal biopsies may show schistosome eggs that were not apparent in stool specimens. Serologic ELISA methods to detect the antibody to parasitic antigens show excellent sensitivity and are of value in population surveys, but may not be helpful in assessing the activity of infection in an individual patient (91). Of the standard abdominal imaging methods, ultrasonography, as discussed earlier, is by far the most practical for field application and appears to be of better diagnostic utility than computed tomography scan (92) or magnetic resonance imaging (93) for assessment of the extent of portal fibrosis.

Medical therapy Praziquantel is an effective drug against all human schistosomes, producing parasitologic cures in approximately 90% of persons (37). It is orally administered, preferably in three doses of 20 mg/kg body weight given over 8 hours for a total of 60 mg/kg. Single-dose therapy of 40 and 50 mg/kg has been used in some community mass treatment programs for S. mansoni and S. japonicum infections, respectively (37). Praziquantel is approved by the U.S. Food and Drug Administration (FDA) for use in schistosomiasis. Gastrointestinal irritation is the major side effect of this generally well-tolerated drug. Another drug effective for S. mansoni infection is oxamniquine, used in mass treatment programs in Africa and South America. Mass treatment programs have become a central element in the efforts of many countries to combat schistosomiasis. For S. mansoni infection, a community-based strategy of mass chemotherapy followed by periodic surveillance with stool examinations and prompt treatment of any reinfections has reduced morbidity and promoted resolution of ultrasonographic evidence of portal fibrosis (61,63,64). Reducing new transmission by largely eliminating the contamination of water with shed parasite eggs underlies this approach. Although promising results have also been achieved in some S. japonicum–endemic areas (62,65), adults in other treated communities show persistence of hepatosplenomegaly and fibrosis even with decreased prevalence of infection (94). The existence of numerous animal reservoirs of S. japonicum in other communities, coupled with the inability of stool examinations to detect all S. japonicum reinfections, suggests that in these locations, frequent mass retreatment would be more effective than surveillance by

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stool examination for reinfection (66,94). In addition, parasitologic cure followed by prompt reinfection might produce a rebound of the relatively severe inflammatory and fibrotic events that accompany acute infection rather than the persistence of a modulated, relatively less damaging long-term response (66). In such a situation, it may be especially important to maintain effective mass retreatment once a decision has been made to begin community-based therapy. There are no clinical data to suggest that specific therapy promotes any greater degree of resolution of schistosomal liver fibrosis in humans beyond what would normally be expected after the cure of active infection, as discussed in the preceding text. However, administration of the immunomodulating Th 1 cytokine interferon-γ to schistosome-infected mice, or promotion of its release by the inhibition of IL-4, diminishes liver collagen deposition (95,96). Schistosomes, along with all other multicellular parasites, continue to defy efforts to produce an effective antiparasitic vaccine. However, a combined antigen–cytokine vaccination concept may help limit parasite-induced host injury: Sensitization of mice with S. mansoni eggs administered together with IL-12 appears to prime the animals to respond with markedly diminished liver fibrosis when they are subsequently challenged with a schistosome infection (97).

Surgical therapy Four major factors contribute to portal hypertension, increased collateral blood flow, and variceal enlargement in schistosomiasis (98,99). They include portal fibrosis that produces presinusoidal obstruction of portal inflow; arterialization of abnormal vessels within the portal fibrous tissue that promotes increased hepatic arterial inflow; cellular infiltration of the spleen that adds to passive congestion to produce marked splenomegaly and increased splenic blood flow; and poorly understood functional disturbances that diminish splanchnic resistance and promote a hyperdynamic splanchnic circulation. Nearly every form of medical and surgical therapy for bleeding varices has been advocated in schistosomiasis. Solid information to support evidence-based P.1368 treatment decisions remains as elusive in schistosomiasis as it is for other causes of variceal bleeding. The results at 4 to 10 years of an important randomized trial of proximal splenorenal shunt, distal splenorenal shunt, and splenectomy with esophagogastric devascularization in schistosomiasis have been reported (100) and critically reviewed (101). Bleeding recurred in one fourth of patients in each surgical treatment group, with slightly more variceal bleeding after splenectomydevascularization. Occurrence of mortality and hepatic encephalopathy, both approximately 40%, was much greater after proximal shunting than after either distal shunting, with 15% mortality and 15% encephalopathy, or splenectomydevascularization, with 7% mortality and no encephalopathy. Taking into account the study's reported limitations, the data support the current reliance on splenectomydevascularization in many centers as the preferred surgical option for variceal bleeding refractory to endoscopic therapy. The procedure may involve either total or segmental splenectomy as discussed earlier. As endoscopic control of variceal bleeding with band ligation and sclerotherapy becomes more effectively practiced and widespread, surgical therapy for bleeding varices is likely to become increasingly limited to devascularization in persons who require splenectomy for other indications, as discussed in the preceding text. The benefits and potential problems of endoscopic sclerotherapy of bleeding varices are similar for schistosomiasis and other liver diseases (102,103,104,105). Growing experience with endoscopic band ligation of varices in schistosomiasis has been encouraging (106,107). A randomized study of band ligation versus sclerotherapy in

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40 Brazilian patients reported similar high efficacy and safety for both procedures, with better patient acceptance of band ligation, and a trend toward fewer sessions required for variceal eradication with band ligation (106). Two controlled secondary prevention trials of propranolol in patients with schistosomiasis and variceal bleeding have shown decreased recurrence of bleeding (108,109). One of these reports from Sudan, which evaluated sustained-release propranalol at a single daily dose of 160 mg, showed a 40% reduction in mortality after 2 years (109). β-Blockade appears to be a useful adjunct for secondary prevention of variceal bleeding in schistosomiasis, in line with its value in other liver diseases, and to merit consideration for evaluation in primary prevention. The general movement toward medical, endoscopic, and nonshunting surgical therapy for variceal bleeding in schistosomiasis shares common ground with the same trends and uncertainties that apply to other liver diseases. Key considerations in schistosomiasis include the frequent occurrence of marked splenomegaly that has attracted interest in evaluating the potential benefits of complete or partial splenectomy, as well as concern about encephalopathy after shunting. Shunted patients require lifelong vigilant prevention of reinfection to avoid iatrogenic pulmonary egg deposition and the development of schistosomal-induced cor pulmonale. Pulmonary hypertension is a known problem even in nonshunted persons with hepatic schistosomiasis, potentially related to incomplete hepatic clearance of vasoactive compounds and mediators (110).

Fascioliasis Fasciola hepatica is a trematode bile duct fluke with a worldwide distribution in sheep and cattle (111). The leaf-shaped male and female adult worms reach a size of approximately 2 cm and may remain viable in the bile ducts for more than a decade. They produce eggs that pass in feces, hatch in water, and infect a snail as an intermediate host. Snails release a cercarial stage of the parasite that contaminates aquatic plants ingested by sheep, cattle, or humans. When ingested, transformed metacercariae penetrate the intestine, traverse the peritoneal cavity and liver capsule, and burrow through the liver parenchyma for 1 to 3 months while maturing, finally entering the bile ducts to become mature adults and complete the cycle. Heavy infection of sheep and cattle, called liver rot, is an important economic cause of livestock loss in areas where animals regularly consume aquatic vegetation. Humans with fascioliasis generally give a history of eating watercress or drinking potentially contaminated water. Human fascioliasis is prevalent in developing countries with humid climates and largely agrarian populations and is less frequently seen in Europe and North America. In the Nile Delta of Egypt, there is a positive association between Fasciola and S. mansoni infections (112). Acute fascioliasis is a febrile illness, typically of up to 3 months duration, presenting with right upper quadrant discomfort and hepatomegaly. As immature flukes continue their course through the liver parenchyma, they leave behind a track of coagulation necrosis infiltrated by an intense eosinophilic inflammatory response. In sheep with experimental fascioliasis, the ability of the parasite to keep moving ahead of the host inflammatory response appears to allow it to literally outrun what would otherwise be an effective host defense (113). The resulting tracks show a characteristic appearance of yellow–white serpiginous subcapsular cords at laparoscopy (114). On computed tomography, the tracks appear as tortuous linear arrays of small, 1- to 3-cm abscess-like lesions (115). In acute fascioliasis, fever, leukocytosis, and right upper quadrant pain are each present in approximately two thirds of patients. In 20 patients reported from P.1369

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Spain, 19 had eosinophilia in the 15% to 65% range (111). Atypical manifestations of acute fascioliasis may result when penetration of the ductal system causes hemobilia or discrete abscess formation (116). Immature flukes that fail to migrate into the liver can produce ectopic masses or abscesses in many locations, most commonly appearing as subcutaneous nodules with an eosinophilic infiltrate surrounding the degenerating parasite tissues. In addition, a syndrome of eosinophilic pleuritis and pericarditis without direct parasitic involvement of these structures may accompany acute fascioliasis (111). After bile duct penetration by mature flukes, egg production initiates chronic fascioliasis. Host responses to adult worms are limited to local inflammation, ductal epithelial proliferation, and fibrous thickening of the duct wall. Fasciola produces proline, a key precursor of collagen, as a major nitrogen excretion product. Animal experiments suggest that high local concentrations of proline in fascioliasis may promote ductal hyperplasia and fibrosis (117). Large numbers of adult flukes in the ductal system may precipitate episodes of acute biliary obstruction and cholangitis (111). In addition to visualization of the adult flukes, dilated ducts may be seen by ultrasonography, computed tomography, or cholangiography. Fever and right upper quadrant abdominal pain in acute fascioliasis, or biliary symptoms in chronic infection, coupled with a consistent dietary history, suggest the possibility of fascioliasis. Eosinophilia and consistent imaging findings as discussed in the preceding text strongly support the diagnosis. Serologic testing for antibody to the parasite was refined by development of an ELISA method using a purified preparation of a Fasciola-specific protease, cathepsin L1, as antigen (118). The assay detected 20 of 26 persons with fascioliasis, with no false positive tests in persons with other helminth infections. An alternative approach using a crude Fasciola worm antigen preparation achieved 97% sensitivity; high specificity of this method required identification of immunoglobulin G (IgG)4 subclass antibody (119). Antibody levels slowly decrease after successful treatment (120). Stool examination for eggs is useful only in chronic disease and may be negative when egg output is intermittent. Bithionol has been the most widely used antihelminthic compound for fascioliasis. It is given in courses of 10 to 30 days for acute and chronic infections (111). Gastrointestinal irritation is common; rash, leukopenia, and hepatotoxicity are less frequent; and retreatment may be attempted for nonresponders to an initial course of therapy. Triclabendazole, a benzamidazole compound widely used in veterinary practice, appears to be more effective and less toxic than bithionol in humans with fascioliasis (121). Limited quantities of bithionol are available in the United States from the Centers for Disease Control and Prevention parasitic drug service as an investigational drug. Triclabendazole, the preferred agent, may now be imported for investigational human use in the United States with FDA approval of an expedited individual use request. A 3- week course of oral metronidazole therapy was recently reported to be effective in Iranian patients who had not responded to triclabendazole (122).

Clonorchiasis and Opisthorchiasis Clonorchis sinensis, Opisthorchis viverrini, and Opisthorchis felineus are bile duct flukes acquired by humans who eat raw fish containing the parasite's infective metacercaria stage. Human hosts excrete eggs that hatch in water and pass through snail and fish stages to infect new humans and animals. With a size of approximately 1 cm and a ventral sucker that permits attachment to the intrahepatic bile duct epithelium, male and female adult flukes have life spans of 10 years or more. C. sinensis infects persons in China and elsewhere in east Asia; approximately one fourth of Chinese immigrants to New York City have active infection (123). O.

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viverrini has a more limited range in Thailand, Laos, and Cambodia but shows very high prevalence in northeast Thailand, where one third of the population is infected (124). O. felineus infects cats and humans in limited areas of Russia and eastern Europe. Most infected persons have relatively light parasite burdens of 100 or fewer worms. For O. viverrini infection, there is a strong quantitative relationship between the number of eggs excreted per gram of stool and a host's burden of adult worms, as determined at autopsy (125) or by retrieval of worms in stool after parasitologic cure of infection (126). A new polymerase chain reaction (PCR)-based fecal test as an alternative for microscopic stool examination may facilitate the screening of large populations (127). Study of the intensity of infection in population-based samples has provided strong evidence to support the linkage of bile duct fluke infection with chronic biliary tract abnormalities and with the ultimate development of cholangiocarcinoma, a leading cause of cancer deaths in endemic areas. In surveys using ultrasonography, the intensity of infection is strongly correlated with the occurrence of gallbladder enlargement and wall irregularity, biliary sludge, and enhanced portal-tract echogenicity (128). For cholangiocarcinoma in northeastern Thailand, a locality-adjusted odds ratio of 14.1 was found for male residents with the highest intensity of O. viverrini infection; 4% of the surveyed male population with more than 6,000 eggs/g feces reportedly had the malignancy (129).

▪ Figure 49.4 Clonorchiasis. A dilated intrahepatic bile duct contains an adult worm cut in cross section. The ductal epithelium shows adenomatous

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hyperplasia (hematoxylin-eosin, ×40). (AFIP Negative 72-11587.)

P.1370 The bile ducts that harbor adult Clonorchis or Opisthorchis worms can show dilatation, irregular thickening, and adenomatous epithelial hyperplasia, as shown in Figure 49.4. Some of these changes may be reversible, especially after treatment of light or early infection. Ten months after eliminating O. viverrini infection with praziquantel treatment, repeated ultrasonographic study of 72 persons showed resolution of gallbladder enlargement, improved gallbladder contractility, and decreases in visible sludge and portal-tract echogenicity (130). However, repeat endoscopic cholangiography at an average interval of 32 months in persons treated for C. sinensis infection showed some improvement in the appearance of the intrahepatic ducts and loss of the filling defects caused by the presence of adult worms but no changes in measured duct enlargement or the presence of duct wall irregularities (131). Adenomatous hyperplasia of the papilla in chronic clonorchiasis can produce radiographic duct abnormalities indistinguishable from those of cholangiocarcinoma (132). The development of cholangiocarcinoma may reflect the interaction of multiple processes. For example, O. viverrini–infected persons with ultrasonographic biliary abnormalities were shown to have increased activity of cytochrome P-450 2A6, an enzyme that promotes activation of carcinogenic nitrosamines (133). Similarly, administration of dimethylnitrosamine to C. sinensis–infected hamsters resulted in development of cholangiocarcinomas that did not occur in uninfected animals or in infected animals not exposed to the carcinogenic compound (134). Although the morbidity associated with biliary fluke infection before the development of cholangiocarcinoma appears to be slight in most persons, the outlook is very poor in those who present with the tumor, similar to that for the same disease in nonendemic areas (135). With currently available information, it seems appropriate to continue efforts to persuade residents of areas with high prevalence of infection and cholangiocarcinoma to modify their dietary habits, and to eliminate existing infection with praziquantel, an easily administered and effective curative drug (124). Screening and parasitologic cure of immigrants to Western countries, who are at high-risk for infection, is also warranted. Oriental cholangiohepatitis is a chronic illness marked by episodes of cholangitis with formation of multiple pigment stones, irregular bile duct dilatation with disproportionate severity in the extrahepatic ductal system, and formation of multiple strictures (136,137). Its geographic range corresponds roughly to that of the bile duct flukes and Ascaris infection. Figure 49.5 shows a cholangiogram from a patient with P.1371 this condition and associated clonorchiasis. In many patients with severe distortion of the ductal system, recurrent episodes of cholangitis appear to be selfperpetuating in the absence of active parasitic infection. Helminth infection should be sought and eliminated in persons with the disease. In addition, recurrences due to obstructing stones may be more easily managed in patients who have had placement of a Roux-en-Y jejunal conduit for biliary access (138).

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▪ Figure 49.5 Oriental cholangiohepatitis associated with clonorchiasis. The cholangiogram shows a dilated, distorted intrahepatic ductal system with contrast material outlining numerous filling defects that represent adult Clonorchis sinensis flukes. (AFIP Negative 96-22949.)

Echinococcosis Echinococcosis, or hydatid disease, develops in humans when they become accidental hosts for a cystic intermediate stage of one of three canine tapeworms, Echinococcus granulosus, Echinococcus multilocularis, or Echinococcus vogeli. Humans become infected by eating food contaminated with eggs excreted by domestic or wild dogs or other canines such as foxes, coyotes, and wolves (139,140). The parasite normally multiplies as a larval scolex stage within cysts in the solid organs of herbivores or rodents that have consumed excreted eggs. Consumption of the cyst-containing viscera of these animals by new canines completes the cycle. Hydatid disease most often affects humans in contact with sheep-herding dogs infected with E. granulosus. The resulting cystic hydatid disease has a worldwide distribution. E. multilocularis infection, concentrated mainly in the arctic and subarctic regions of the Northern Hemisphere, causes human alveolar hydatid disease. E. vogeli, the cause of human polycystic hydatid disease, has a very limited range in Central and South America (141). Hydatid liver cysts caused by E. granulosus, as shown in Figure 49.6, are most often asymptomatic. They are fluid-filled structures delimited by a parasite-derived

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membrane, as shown in Figure 49.7A, which contains germinal epithelium that buds viable scoleces, shown in Figure 49.7B. Imaging by ultrasonography, computed tomography (as shown in Figure 49.6), or magnetic resonance may demonstrate the formation of daughter cysts, cyst wall calcification, and compression and fibrous reaction of the surrounding liver parenchyma, and in complicated disease, communication of the cyst with the biliary system or external leakage of cyst material. The cysts formed in E. multilocularis infection are less well delimited. They tend to invade the liver parenchyma and seed adjacent organs and structures with scoleces and daughter cysts (142). The polycystic hydatid disease of E. vogeli infection shows well-delimited multiple cysts (141).

▪ Figure 49.6 A: Hepatic hydatid cyst of Echinococcus granulosus, opened to show folds of the pale thickened germinal membrane associated with translucent budding daughter cysts. (AFIP Negative 95-82642.) B: Hepatic hydatid cyst of Echinococcus granulosus. A computed tomographic image shows a large cyst in the posterior right lobe of the liver with a complex internal structure similar to the cyst shown in (A) and areas of wall calcification. (AFIP Negative 92-84646.)

Cystic hydatid disease now most often presents as a hepatic mass with a typical appearance on abdominal imaging, coupled with confirmatory serologic testing by indirect hemagglutination or ELISA, which is positive in approximately 90% of hydatid cysts (140). As discussed in the preceding text, no fecal eggs are present in human hosts. Eosinophilia is usually present. Biliary or peritoneal extension or pulmonary cystic disease is usually easily recognized; however, ectopic cysts in the kidney, spleen, brain, orbit, heart, and bone may produce unusual findings. Uncommon presentations of hydatid disease include segmental portal hypertension due to splenic vein compression by a cyst in the splenic hilum, with adjacent perihilar varix formation (143), and rupture of a hepatic cyst causing inferior vena cava thrombosis (144). Until recently, most hydatid cysts came to clinical attention because of symptomatic enlargement, so that their management by surgical excision was a straightforward decision. Palliative resections for the spreading, poorly contained cysts of E. multilocularis–induced alveolar hydatid disease were often inadequate to deal with this frequently lethal disease. P.1372 Now that many hydatid cysts are detected as incidental findings during abdominal imaging and newer forms of medical and surgical therapy for hydatid disease are being reported, therapeutic options are at once more promising and more

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challenging.

▪ Figure 49.7 A: Hepatic hydatid cyst of Echinococcus granulosus. Laminated membrane, top, and debris within the cyst (hematoxylin-eosin, ×160). (AFIP Negative 82-12615.) B: Hepatic hydatid cyst of E. granulosus, showing viable scoleces cut in cross section (hematoxylin-eosin, ×250). (AFIP Negative 8212530.)

After initial evaluation of the benzimidazole antihelminthic compound mebendazole, a related compound, albendazole, has become the current standard for medical therapy of hydatid disease (145,146,147,148). Albendazole has strong scolicidal activity for E. granulosus and E. multilocularis and superior absorption, bioavailability, and distribution into hydatid cysts compared with mebendazole (145). Albendazole was reported to be an effective preoperative adjunct for disrupting the viability of E. granulosus and E. multilocularis cysts and improving resectability in the latter disease (142,146,147). Albendazole was studied as primary therapy in 59 persons with hepatic E. granulosus cysts of diameter 10 cm or less: After 3 to 7 years, cysts had fully resolved in 24 patients, decreased in size in another 24, not changed in 9, and recurred after initial resolution in 2 (148). In another series of 19 patients treated with a combination of albendazole and praziquantel for 2 to 6 months, the combination was reported to produce more rapid and complete resolution than that seen in 22 patients treated earlier by the authors using albendazole alone (149); however, the results of combination therapy in this report were similar to those reported by others for albendazole alone. In an extensive series of 929 cysts in 448 persons treated with mebendazole or albendazole with up to 14 years follow-up, approximately 1 in 4 cysts recurred after initial resolution or regression (150). Recurrence was greatest within 2 years of resolution. Albendazole, approved for use in the United States, is generally administered two to three times daily with food at doses ranging from 10 to 50 mg/kg per day, for 12 to 24 weeks or longer, with or without intervening rest periods (145,146,147,148). Toxicity includes variable alopecia and, in many patients, minor elevations in aminotransferase levels as well as transient pain perceived at the location of a cyst on initiation of treatment. Elevation of aminotransferase levels more than four times normal or leukopenia requires discontinuing albendazole. Traditional surgical therapy for hepatic E. granulosus cysts at laparotomy includes isolation by packing; careful aspiration of cyst fluid to avoid spillage of viable scoleces or anaphylaxis; injection of the cyst with hypertonic saline, alcohol, or dilute silver nitrate to kill the scolices if the aspirated fluid is crystal clear; and

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resection of either the cyst alone or both the cyst and its pericystic rim of compressed liver tissue (151,152). Aspiration of turbid cyst fluid suggests a biliary communication so that injection with potential sclerosants is avoided. The use of percutaneous drainage, described in the subsequent text, for an increasing proportion of patients with relatively simple cysts, has left the remaining patients who now come to open surgery as a population with relatively greater aggregate complexity and technical challenge than those of earlier surgical series. Laparoscopic evacuation (153) and ultrasound-guided percutaneous drainage (154,155,156,157,158) are reported to be safe and effective for treating uncomplicated cystic hydatid disease. Percutaneous drainage has become the firstline management for cystic hydatid disease in many centers. The most extensive current experience is with an ultrasound-guided four-step process of puncture; aspiration; injection with hypertonic saline, silver nitrate, or other scolicidal solution; and re-aspiration (PAIR) method, with one or more days of subsequent percutaneous catheter drainage for P.1373 large cysts. Patients normally receive a several day preprocedure course of oral albendazole, and are given antihistamine and steroid coverage for the procedure to minimize anaphylaxis in the event of cyst leakage at puncture, followed by continued albendazole for 2 months after the procedure. Advantages of the PAIR technique include minimal disability and early return to full activity, with a 1- to 2-day length of hospital stay compared to a typical 2-week stay after open cyst evacuation. In contrast to primary medical therapy without aspiration and drainage, the PAIR technique has the advantages of a much shorter duration of 2 months of adjunctive albendazole therapy postprocedure, compared with up to 6 months or more for albendazole as primary treatment, as well as a minimal recurrence rate compared with recurrence of 25% of cysts treated medically alone (150). PAIR and laparoscopic cyst evacuation in experienced centers have both shown low morbidity, with anaphylaxis being the most significant problem in the 1% to 2% range, which is generally easily managed in pretreated patients, and the potential for bleeding or duct injury common to all liver punctures. Patients with alveolar hydatid disease due to E. multilocularis have an infection whose biologic behavior resembles that of a malignant tumor as its complex cystic structures invade the liver parenchyma and spread by direct extension to adjacent sites. Albendazole therapy is administered in an effort to stabilize unresectable disease, or as an adjunct to liver resection, which may cure early localized disease. Alveolar hydatid disease may require multiple surgeries in an attempt to deal with severe complications such as hepatic vein compression and thrombosis, and secondary sclerosing cholangitis. Similar major problems occur much less frequently in cystic hydatid disease. Liver transplantation for patients with end-stage alveolar or cystic hydatid disease often presents a technical challenge related to extensive prior surgery, but transplantation may produce a good long-term outcome in patients whose disease has progressed beyond the point of cure or control by other methods (159,160).

Annotated References Arjona R, Riancho JA, Aguado JM, et al. Fascioliasis in developed countries: a review of classic and aberrant forms of the disease. Medicine 1995;74:13–23. An excellent clinical review including 20 patients from the authors' hospital showing the full spectrum of acute and chronic fascioliasis. Bastani B, Dehdashti F. Hepatic hydatid disease in Iran, with review of the

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literature. Mt Sinai J Med 1995;62:62–69. A thorough discussion of findings and surgical outcomes for 126 patients with hepatic echinococcosis from an endemic area in Iran. Haswell-Elkins MR, Mairiang E, Mairiang P, et al. Cross-sectional study of Opisthorchis viverrini infection and cholangiocarcinoma in communities within a high-risk area in northeast Thailand. Int J Cancer 1994;59:505–509. A definitive epidemiologic and clinical study from northeastern Thailand showing a strong quantitative relationship between intensity of chronic infection and relative risk for the development of cholangiocarcinoma. Montalban C, Calleja JL, Erice A, et al. Visceral leishmaniasis in patients infected with human immunodeficiency virus. J Infect 1990;21:261–270. Clinical presentation of visceral leishmaniasis in 40 HIV-infected patients from ten hospitals in Madrid and Barcelona, including evidence to support the consideration of visceral leishmaniasis as an AIDS-defining illness. Olds GR, Dasarathy S. Recent advances in schistosomiasis. Curr Infect Dis Rep 2001;3:59–67. A clear review of the key points of immunopathology, clinical manifestations in individual patients, and population health aspects of schistosomal infection.

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Editors: Schiff, Eugene R.; Sorrell, Michael F.; Maddrey, Willis C. Title: Schiff's Diseases of the Liver, 10th Edition Copyright ©2007 Lippincott Williams & Wilkins > Table of Contents > Volume 2 > Section XI - Infectious and Granulomatous D isease > Chapter 50 - Bacterial and S ystemic Infections

Chapter 50 Bacterial and Systemic Infections Stuart C. Gordon

Key Concepts z

z

z

Involvement of the liver with various bacterial, fungal or rickettsial infections may be a primary disorder or part of a multisystemic disorder. These infections often mimic other conditions, therefore a high degree of clinical suspicion is often needed to establish the diagnosis of nonviral hepatic infection. Cholestasis and hyperbilirubinemia can occur after gram-positive or gram-negative bacteremia, even in the absence of fever or positive blood cultures, and is often an overlooked entity. Endotoxin-mediated cytokine release is the likely cause of septic jaundice. The possibility of a nonviral hepatic infectious disorder should be suspected when a patient with a fever has a cholestatic biochemical profile (predominant alkaline phosphatase elevation out of proportion to the aminotransferase derangement). Occupational and travel history may provide diagnostic clues, and results of specific serologic tests or biopsy of the liver may lead to the institution of appropriate therapy.

z

Although in the past many nonviral hepatic infectious diseases were diagnosed retrospectively with serologic titers or microbiologic cultures, currently polymerase chain reaction (PCR) (candidiasis, tuberculosis, tularemia, leptospirosis, Q fever) is increasingly used to facilitate early diagnoses.

A variety of bacterial, fungal, and rickettsial infections affect the liver, either as the result of direct hepatocellular or biliary invasion or through the production of toxins. In addition, systemic infectious processes frequently cause jaundice or nonspecific liver biochemical abnormalities through mechanisms that are less defined. The jaundice of bacterial pneumonia has been long recognized (1,2), and both jaundice and aminotransferase abnormalities have been associated with other systemic infections, including appendicitis (3), bacteremia in infants (4,5), and other extrahepatic infections (6,7). Most descriptions of liver dysfunction during systemic infection were reported several decades ago, whereas recent research has focused on the mechanisms of the jaundice of sepsis. Reports of the hepatobiliary manifestations of specific infectious agents come from around the world; newly recognized manifestations, diagnostic modalities, and treatment regimens shed new light on the clinical relevance of these conditions. Anecdotal case reports emphasize the need for clinicians to consider the possibility of such infectious agents and entities when encountering unusual cases of hepatitis or cholestasis.

Bacterial Infection and Jaundice The observation that extrahepatic bacterial infection can cause jaundice has been attributed to Garvin (8). Osler (9) in 1892 found that in patients with pneumonia, jaundice might occur. The syndrome of septic jaundice is highly variable and may range from nonspecific P.1380 biochemical cholestasis to deep jaundice. Sepsis as a cause of jaundice in the hospitalized patient is often an overlooked entity (10). A disproportionate elevation of serum bilirubin in comparison with serum alkaline phosphatase and aminotransferase levels should suggest underlying sepsis, even in the absence of fever or leukocytosis (11). Accordingly, early medical or surgical intervention may reduce morbidity and mortality (11). In more than one third of patients with sepsis, hyperbilirubinemia associated with bacteremia with or without an increase in serum alkaline phosphatase level may occur 1 to 9 days before the initial positive blood culture result is obtained. Although gram-negative bacteria, especially Escherichia coli, have been implicated as the predominant causative agent in most series, infection with nonhepatic gram-positive organisms, especially Staphylococcus aureus (12,13) also have been cited. The mechanisms by which bacterial infection causes cholestasis and jaundice are not clear, but endotoxemia appears to be the likely cause. Lipopolysaccharide (LPS), or endotoxin, is contained within the outer membranes of gram-negative bacteria and is a potent inducer of cytokines. Endotoxemia may occur in the absence of documented sepsis (14), and increased levels of tumor necrosis factor α and other cytokines occur in alcoholic hepatitis and in jaundice associated with total parenteral nutrition. Accordingly, endotoxin-mediated cytokine release may be the basis for the jaundice of many disorders, including sepsis (15,16). Early studies showed a reduction in bile flow and biliary excretion after administration of endotoxin to isolated, perfused rat liver. Pretreatment with dexamethasone, which blocks endotoxin-mediated release of the cytokines tumor necrosis factor α and interleukin-1, largely prevented this reduction in bile flow (11,17). The cholestasis of sepsis has long suggested an impaired hepatocyte transport of bile acids and organic anions. Studies have shown that canalicular bile acid and organic anion transport are markedly impaired in endotoxemia (18). Therefore, endotoxemia severely impairs the transport of organic anions at both the sinusoidal and canalicular membrane. Because of impaired hepatic organic anion transport, both bile acid–dependent and bile acid–independent

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components of bile flow decrease with the administration of endotoxin. Li et al. (19) recently demonstrated that LPS administration decreases organic anion transport mRNA levels in mice, and that this decrease is mediated through toll-like receptor 4 (TLR4). The jaundice of sepsis was historically described as occurring in pediatric patients, but its presence in adults is increasingly observed. Marked elevations in direct and total serum bilirubin concentrations occur in bacteremic adults (20,21). In a review of 100 consecutively enrolled adult and pediatric patients with positive results of blood cultures (4), 54% had elevated serum bilirubin levels, and 34% had values of 2.0 mg/dL or greater. The condition may be more prevalent among patients with preexisting liver disease, whereas only 6% of patients without preexisting hepatobiliary disease had jaundice in another series (22). The molecular pathogenesis and pathophysiology of cholestasis has been reviewed (23,24). Secretion of bile depends on the adequate functioning of many membrane transport systems in both hepatocytes and cholangiocytes, and various molecular defects in hepatocellular membrane transporters are associated with cholestatic liver disease in humans. At present, ursodeoxycholic acid (ursodiol) is used in many cholestatic liver diseases, presumably because it replaces toxic hydrophobic bile salts in serum, liver, and bile. At present, however, ursodiol has no accepted role in the cholestasis of sepsis. A better understanding of the molecular mechanisms involved in cholestatic syndromes should unfold the potential for newer therapies (23).

Specific Bacterial Infections Salmonella Hepatitis (Typhoid Fever) Both Salmonella typhi and Salmonella paratyphi cause the acute systemic disease enteric fever. It has been estimated that 16 million cases occur per year, with at least 600,000 deaths, making typhoid fever a major public health problem in less developed regions of the world (25). Although clinical hepatitis is unusual (probably fewer than 25% of all cases), liver involvement is present in almost all cases (26). The term salmonella hepatitis refers to liver injury caused by infection with either S. typhi or S. paratyphi, and the disease has been documented in both endemic and nonendemic areas. Among the 150 cases of salmonella hepatitis reported to date, most occurred in patients with typhoid infection. The disease affects people of all ages, and those with immune deficiency are particularly at risk. Among persons with human immunodeficiency virus (HIV) infection, the most commonly isolated serotypes are Salmonella enteritidis and Salmonella typhimurium (25). Alcoholism has been identified as a predisposing factor for severe forms of S. enteritidis infection in cases in which no other underlying disease has been evident (27,28,29). The mechanism by which the organism causes hepatitis is not established. It may be related to either direct hepatic damage from endotoxin or the inflammatory process or to immune mechanisms. In a rodent P.1381 model of Salmonella infection, the organism invaded and multiplied extensively in hepatocytes. Thereafter destruction of infected hepatocytes by inflammatory phagocytes was followed by a release of bacteria into the extracellular space. The findings suggested that lysis of infected hepatocytes by phagocytic cells was an important early-defense strategy against liver infection with S. typhimurium (30). Similar mechanisms of infection occurred with Francisella tularensis and Listeria monocytogenes (see subsequent text). There is also evidence to suggest that the severity of the hepatitis in typhoid fever correlates with the virulence of the infecting organism (31,32). The liver histology of salmonella hepatitis is nonspecific. Ballooning degeneration with vacuolation has been reported. Reticulum endoplasmic dilatation, mitochondrial alterations, and biliary canaliculus injury have been described. Occasionally, S. typhi organisms are found in the liver cells, as are lobular aggregates of Kupffer cells, lesions known as typhoid nodules (33,34). Such nodules simulate granuloma formation and represent hyperplasia of the reticuloendothelial system. This hyperplasia reportedly causes hepatic enlargement in patients with enteric fever (35). The clinical presentation of salmonella hepatitis resembles that of viral hepatitis, but certain features help in differentiating the two diseases. In particular, high fever (often >40°C) and bradycardia (inappropriate response of heart rate to degree of fever) seem to be more common among patients with salmonella hepatitis. In addition, the biochemical profile is markedly different from that of viral hepatitis and suggests the presence of an infiltrative process rather than hepatitis. In a comparison of 27 cases of salmonella hepatitis with acute viral hepatitis, El-Newihi et al. (36) found that patients with salmonella hepatitis were more likely to have a disproportionately increased serum alkaline phosphatase level and that serum aminotransferase values were far lower than with acute viral hepatitis. Also unlike viral hepatitis, salmonella hepatitis was associated with fever and a left shift of white blood cells (37). Jaundice is unusual, and many cases of salmonella hepatitis are anicteric. In untreated patients, jaundice may be delayed appearing in the second to the fourth week of the illness. Among patients with jaundice, and presumably more severe disease, glomerulonephritis (characterized by increased blood urea nitrogen and serum creatinine levels, proteinuria, and urinary sediment red cell casts) has been more common (38,39). In the more severe cases, in addition to glomerulonephritis, complications include liver abscess, cholangitis, encephalitis or neuropsychiatric manifestations, myocarditis, or bleeding diathesis. Disseminated intravascular coagulation with extensive gangrene of the extremities and rhabdomyolysis has been described (27). Establishing a diagnosis of salmonella hepatitis may be difficult in developing countries, because the manifestations are similar to those of other forms of acute hepatitis, including viral hepatitis, leptospirosis, and malaria. The biochemical profile described earlier helps to differentiate the various entities. The alanine aminotransferase (ALT) to lactate dehydrogenase (LDH) (ALT/LDH) ratio usually is less than 4.0 in salmonella hepatitis. A ratio greater than 5.0 is reported in acute viral hepatitis, and a ratio less than 1.5 occurs in cases of central zonal injury, such as hepatic ischemia or acetaminophen injury (36). Prompt diagnosis and early intervention with appropriate antibiotics assure a good prognosis. Because of

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salmonella resistance to the so-called first-line antibiotics (chloramphenicol, trimethoprim-sulfamethoxazole, and amoxicillin), antibiotic sensitivity testing is advised. A 5-day course of fluoroquinolone is the therapy of choice for uncomplicated enteric fever. Some experts have advocated the addition of intravenous dexamethasone (40). Because the organism can enter the bile and reside in the gallbladder, shedding for long periods can cause the chronic carrier state. Follow-up stool cultures are advised for all patients with typhoid fever to ensure that they are not carriers, and long-term fluoroquinolone therapy may help eradicate the carrier state (35). The prognosis for salmonella hepatitis is excellent; death has occurred among patients with malnutrition and immunodeficiency.

Tuberculosis There has been a renewed interest in tuberculous infection of the liver because of the increasing incidence of extrapulmonary tuberculosis related to acquired immunodeficiency syndrome. In such cases, Mycobacterium avium-intracellulare is often the cause of liver dysfunction (see Chapter 51). Classically, however, hepatic tuberculosis (infection with Mycobacterium tuberculosis) as a part of miliary disease may occur in as many as 80% of all patients dying of pulmonary tuberculosis (41). The original description of hepatic tuberculosis classified the disease as (a) miliary, a part of generalized disease, or (b) local, with focal involvement of the liver. The terms that have led to confusion over the years included tuberculous pseudotumor, atypical hepatic tuberculosis, tuberculous cholangitis, and tuberculous liver abscess (42). One classification scheme (42) separates hepatic tuberculosis into three categories: Miliary, granulomatous, and localized hepatic. The miliary form, which is part of generalized miliary disease, usually does not involve the liver. Granulomatous disease, that is, hepatitis due to tuberculosis, is defined by the finding of typical caseating granulomas at liver biopsy and response to appropriate antimicrobial therapy. Finally, P.1382 localized hepatic tuberculosis is further classified into disease that is either (a) without bile duct involvement (e.g., solitary or multiple hepatic nodules or tuberculous abscess) or (b) with bile duct involvement due to either compression of the bile duct by lymph nodes or actual involvement of the ductal epithelium by the tuberculous process. Therefore, the term hepatobiliary tuberculosis refers to a distinct clinical entity of localized hepatic disease with characteristic clinical features. The portal of entry of M. tuberculosis organisms into the biliary tract and the liver is the hematogenous route or, less commonly, the portal vein or lymphatic vessels (43). Therefore disease that is isolated to the liver is considered rare, even in the absence of documented disease elsewhere; often inactive pulmonary tuberculosis is found at autopsy. One variant form of hepatic tuberculosis without active pulmonary or miliary disease is the socalled “nodular form,” which presents as an isolated liver tumor or abscess (44,45). In most cases, the clinical presentation is that of neoplasm, with solitary liver lesions of variable size and imaging features, raised alkaline phosphatase values, weight loss, and so on, in the absence of known previous tuberculosis. In one recent series, PCR assay of the liver tissue in five cases established the etiologic diagnosis of M. tuberculosis, with postoperative histologic diagnoses only showing chronic granulomatous inflammation. Such cases underscore the difficulty in reaching the correct diagnosis of hepatic tuberculosis, the value of PCR technology in establishing this diagnosis, and the need for a high index of suspicion (44). The clinical manifestations of hepatobiliary tuberculosis are those of the extrahepatic disease; hepatic involvement usually produces no symptoms (46). Nevertheless, cases of fulminant hepatic failure have been reported, among both immunosuppressed and immunocompetent persons (47,48). In one summary of cases of gastrointestinal tuberculosis in California, patients with hepatic involvement usually had right upper quadrant pain or fever of unknown origin (49). Nonspecific abdominal pain may be present in patients with chronic tuberculosis, whereas fever and weight loss are common in cases of tuberculous abscess. The most common physical finding is hepatomegaly, which probably occurs in most cases (46,50). A disproportionately increased serum alkaline phosphatase level is a consistent finding (51), which suggests the presence of an infiltrative hepatic process, whereas nonspecific aminotransferase elevations do not aid in diagnosis (52). The presence of jaundice suggests biliary involvement, and the biochemical profile may simulate that of extrahepatic biliary obstruction (53). An unusual manifestation of tuberculosis involves the development of portal hypertension caused by the compression of the portal vein by tuberculous lymph nodes, followed by the rupture of esophageal varices and hematemesis (54). Isolated pancreatic tuberculosis may manifest in a manner very similar to that of a pancreatic neoplasm, including a mass lesion of the pancreatic head (55). Similarly, gallbladder tuberculosis is reportedly increasing in incidence and may manifest as biliary colic and acute cholecystitis (56). Another unusual but increasingly reported variant of hepatobiliary tuberculosis is obstructive jaundice caused by the involvement of the bile duct, pancreas, or gallbladder. Compression of the biliary tree by involved lymph nodes or possibly by direct involvement of the biliary epithelium or rupture of a caseating granuloma into the lumen of the bile duct may cause jaundice and biochemical cholestasis. Intrahepatic bile duct obstruction may result from granulomatous involvement, often as part of miliary tuberculosis. The entity of bile duct tuberculosis (57) may manifest as bile duct dilatation and common hepatic duct strictures. Biliary cytologic findings from endoscopic cholangiography may yield the diagnosis (58). Such patients have painless jaundice and weight loss that mimics malignant disease of the pancreas or cholangiocarcinoma, and dilated bile ducts are found at imaging studies. Experience with therapeutic biliary stenting has been variable, and in unsuccessful cases, percutaneous biliary drainage decompresses the obstruction (59,60). Imaging studies may help rule out other conditions. Plain radiographs may show hepatic calcifications in patients with chronic tuberculosis, and both ultrasonography and computed tomography (CT) may show complex masses, either solitary or multiple. Such masses, common in patients with tuberculous liver abscesses, cannot be differentiated from malignant tumors and necessitate aspiration or biopsy for further investigation. One patient with cirrhotic hepatitis C and end-stage renal disease presented with multiple hyperechoic hepatic lesions on ultrasound, without pulmonary involvement (61). Blind percutaneous liver biopsy may be useful in the diagnosis of

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the miliary form, whereas direct-guided biopsy with laparoscopy results in a higher diagnostic yield. At laparoscopy, a cheesy white appearance of irregular nodules, often resembling malignant tumor, has been described (42,62). Although the finding of caseating granuloma is highly suggestive of tuberculosis (Fig. 50.1), similar pathologic findings occur in brucellosis, coccidioidomycosis, and Hodgkin's disease. Caseation is commonly associated with tuberculosis, but in some series it occurs less frequently. The finding of acid-fast bacilli at biopsy occurs infrequently, fewer than 35% of cases, and the yield of a positive culture result for M. tuberculosis itself is even less common. Molecular techniques establish the diagnosis of hepatic tuberculosis. Akcan et al. (63) and Alcantara-Payawal et al. (64) reported very high sensitivity (overall assay positivity of 88% in one series) with P.1383 low false-negativity among control patients, from a PCR assay on the liver tissue of patients with infection.

▪ Figure 50.1 Tuberculosis. Caseating hepatic granuloma in a patient with fever of unknown origin.

The management of hepatic tuberculosis involves the use of at least four antituberculous drugs, usually including isoniazid, rifampicin, pyrazinamide, and ethambutol (65). Although therapy traditionally lasts at least 6 months, multidrug resistant organisms require alternative chemotherapies, and there is a genuine need for new agents. It is anticipated that implementation of the recently developed molecular assays for M. tuberculosis will serve to assess response to therapy and allow individualized treatment duration.

Legionnaires Disease Although most forms of pneumonia may cause derangements in liver function, Legionnaires disease, pneumonia characterized by multisystemic involvement, is particularly likely to cause abnormal results of liver tests. In one large review (66) both aminotransferase levels (up to 15 times the upper limit of normal) and alkaline phosphatase levels (up to 9 times the upper limit of normal) accompanied the pneumonia. Fifteen percent of patients also had hyperbilirubinemia. Therefore, the finding of markedly abnormal liver biochemical values in the presence of obvious pneumonia may be a clue to the appropriate diagnosis. The organism can be found with direct immunofluorescence or other techniques (Fig. 50.2) (67). Deranged liver biochemistries may represent the main manifestation (68).

Brucellosis Three species of Brucella affect humans: Brucella melitensis, Brucella abortus, and Brucella suis. Brucellosis is an occupational disease that affects food handlers, and organisms enter the body through the skin or oropharynx and spread to regional lymph nodes. The disease can also be airborne and transmitted to personnel in microbiology laboratories.

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▪ Figure 50.2 Legionella pneumophila serogroup 3. Antigenic material within sinusoidal lining cells in the liver (direct immunofluorescence, 512×). (Courtesy of John Watts, MD.)

The involvement of the liver in human brucellosis may occur with infection by both B. melitensis and B. abortus. The incidence of liver disease in brucellosis depends on the definition. Colmenero et al. (69) proposed that the concept of hepatic complication of systemic brucellosis be reserved for patients with obvious hepatic dysfunction, including jaundice or abscess. Defined in these terms, only 2.4% of 530 patients with B. melitensis infection had hepatic complications, whereas the presence of hepatic granuloma in the absence of overt hepatitis may be more common. In a study of 905 patients with brucellosis, Ariza et al. (70) found 16 cases of chronic hepatosplenic suppurative brucellosis (14 in the liver and 2 in the spleen) among 15 patients. One half of the patients had previous remote brucellosis. Although hepatic abscess formation after acute infection is unusual, mild nonspecific liver enzyme abnormalities may be detected in approximately 50% of patients with brucellosis. In addition to hepatic involvement, spontaneous bacterial peritonitis can occur in the absence of obvious hepatic involvement (71,72). Febrile and fatal hepatitis with hepatic abscess and endotoxic shock has been described (73). Carazo et al. recently described the imaging features in cases of hepatosplenic brucelloma, and noted that on ultrasound, the lesion appears iso- or hypoechogenic with the liver, with focal calcifications. Contrast-enhanced CT scans showed predominantly solid masses with irregular borders, rarely with transdiaphragmatic lung invasion (74). Histologic examination of the liver in brucellosis usually shows nonspecific portal and lobular inflammation, and small noncaseating granulomas are often associated with reactive hepatitis (Fig. 50.3). The finding of granuloma is constant when the duration of the P.1384 disease is less than 100 days but is infrequent after this time (75). The predominant biochemical derangement in clinically apparent disease is an increase in serum alkaline phosphatase level. This finding suggests the presence of an infiltrative process. The organism can be isolated from the blood in acute states, but cultures may take 3 weeks to turn positive. Agglutinating antibodies generally appear after the second week of illness, and the diagnosis usually is established by the demonstration of increasing titers. Therefore, the presence of acute infection may be established by isolation of the microorganism or by appropriate serologic findings. These diagnostic criteria may not be helpful, however, for chronic forms of the disease, which may have evolved over long periods.

▪ Figure 50.3 Brucella melitensis. Nonspecific lymphoplasmacytic inflammatory infiltrate in patient with brucellosis (hematoxylin and eosin, 510×). (Courtesy of John Watts, MD.)

The more serious form of the disease therefore involves hepatic abscesses, and imaging studies show large calcium densities within the liver. Many such patients had known brucellosis many years earlier and were free of symptoms before the development of the abscess. However, even among patients without previous brucellosis, the finding of hepatic calcium deposits when the patient first arrives for evaluation strongly suggests that this entity represents a local reactivation of a previous undocumented brucellosis, as in tuberculosis (70). In the United States, the manifestation of brucellosis among children as hepatosplenic abscess may cause diagnostic confusion, particularly among immigrants and travelers from countries where brucellosis is endemic (76). Unlike patients with acute brucellosis, patients with hepatic abscess (chronic hepatosplenic suppurative brucellosis or “brucelloma”) tend not to have either leukopenia or relative lymphocytosis, and biochemical abnormalities are minor (68,75). The differential diagnosis includes neoplasm, hydatid disease, pyogenic or amebic abscess, and other granulomatous infections, including tuberculosis and histoplasmosis (77). Such patients often have had very low titers of agglutinating antibody that have delayed appropriate diagnosis. The drugs administered for therapy for acute infection are tetracycline and rifampicin. In cases of chronic suppurative disease, percutaneous or surgical drainage should be performed (70,78).

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Tularemia Infection with F. tularensis, the causative agent of tularemia, occurs after exposure to jackrabbits and hares, the main animal reservoir in North America and Europe. Hunters are at risk and may acquire the disease from tick or deer-fly bites in the summer months. In Sweden, the lemming is responsible for this disease (“lemming fever”), whereas in Russia the water rat and muskrat may spread tularemia. The disorder usually affects the lungs, and the usual manifestation is a flu-like syndrome occurring between 1 and 10 days after exposure. Liver involvement is rare, and when it does occur, only modest aminotransferase abnormalities are found (79). Tularemia also manifests as obstructive jaundice with fever, suggesting the presence of cholangitis. A cholestatic biochemical profile may cause a diagnostic dilemma in such cases (80). Early diagnosis and management of tularemia probably account for the rarity of hepatic dissemination, but hepatic tularemia may also manifest as a solitary hepatic abscess early in the course of disease (81). Histologic examination of the liver in cases of tularemia shows multiple focal areas of coagulative necrosis with a surrounding chronic inflammatory infiltrate (82). The diagnosis can be established serologically with demonstration of agglutinating antibodies. Enzyme-linked immunosorbent assay (ELISA) tests are available, but a PCR test for F. tularensis should enable rapid confirmation of the clinical diagnosis of tularemia (83). Treatment consists of streptomycin or gentamicin.

Listeriosis L. monocytogenes is an organism found mostly in rodents. It is widely distributed in nature, including soil and plant material. It usually causes meningoencephalitis or pneumonitis, although hepatic involvement is reported. The liver disease of listeriosis is more common in neonates, but in adults, it may manifest as signs and symptoms of viral hepatitis, usually with high fever (84). Patients are often immunosuppressed or have underlying malignant disease (85). The onset may be gradual over several weeks or immediate fulminant hepatitis. Aminotransferase levels may be high, and jaundice may be present. The presence of high fever and leukocytosis tends to differentiate this condition from viral hepatitis, and the diagnosis is confirmed by the isolation of the organism from blood or cerebrospinal P.1385 fluid. The disease may also manifest as a liver abscess, in which case the diagnosis is established by culturing aspirated abscess material (86).

Melioidosis Melioidosis is endemic to northeastern Thailand but is also found throughout Southeast Asia and northern Australia. It is a potentially fatal infection caused by the bacterium Burkholderia pseudomallei (formerly Pseudomonas pseudomallei). The organism is ubiquitous in many parts of the tropics, and is found in damp soil and freshwater. The usual mode of acquisition is through inhalation or through minor skin abrasions. The mortality may be high, averaging 45%, and in cases of acute septicemia, death occurs within the first 3 days after hospital admission. The disease has protean manifestations, and histopathologically it mimics tuberculosis and catscratch disease. Early diagnosis and proper antibiotic therapy (parenteral ceftazidime was provided for 4 weeks in the report of Ben et al. (87)) are crucial. Melioidosis may present with pulmonary infection, tonsillitis, localized abscess or fulminant septicemia (87). Liver involvement in melioidosis is common, but the increase in aminotransferase and serum bilirubin values is similar to that among patients with other forms of bacteremia. Visceral organ abscesses are common and usually involve the spleen, liver, and kidney. Granulomas may be found. The sonographic appearance of these multiple, small, discrete abscesses is target-like, and larger multiloculated abscesses are common (88). The differential diagnosis of melioidosis includes other forms of liver abscess, tuberculosis, and other bacterial causes of sepsis. Immunohistochemistry plays a useful diagnostic role, and polyclonal antibodies applied to formalin-fixed, paraffinembedded tissue help establish the diagnosis earlier than the traditional but less reliable culture techniques (89).

Spirochetal Infections Leptospirosis Professor Weil of Heidelberg first made the classic description of febrile headache, jaundice with renal failure, and severe muscle pain, which is now known as Weil disease. Yet only a small percentage of patients infected by spirochetes of the genus Leptospira have this most severe of manifestations, and most descriptions of liver pathology in this disease come from autopsy series. Early recognition, with administration of appropriate antibiotics, has resulted in a very low incidence of hepatic manifestations. Leptospirosis has a worldwide distribution. It results from direct or indirect exposure to the urine of infected animals, usually rodents. The most common serotypes are Leptospira icterohaemorrhagiae, carried by rats, and Leptospira canicola, carried by dogs. The organism enters the body through wounds on the skin and through intact mucous membranes and can directly penetrate the skin. Therefore the disease often results from occupational exposure, as among persons who work in sewers, mines, and construction sites and among food workers who may be exposed to rodent-infested environments. Leisure activities that include swimming, white-water rafting, or fishing in rivers or ponds contaminated with infected urine from wild animals also have resulted in leptospiral infection (90). In Thailand, risk factors include walking through water, applying fertilizer or plowing wet fields (91). Eating uncooked rice has been reported as a risk factor because of contamination with rat urine (90). Although usually considered a disease of developing nations, cases occur in the United States and may cause a diagnostic dilemma. Among immunosuppressed HIV-infected patients, homelessness in large cities may result in exposure to rodent urine and resultant urban leptospirosis (92). The usual manifestations are acute fever and a

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flu-like illness, often with cough and chest pain, that occur after a 7- to 10-day incubation period. The abdominal pain of the acute phase may simulate surgical abdomen and may manifest as biliary colic. At a recent triathlon in Illinois, which included swimming in a freshwater lake, two athletes had clinically suspected acute cholecystitis and underwent cholecystectomy. An immunohistochemical test for leptospirosis applied to these gallbladders showed bacterial antigens and intact bacteria (93). Central nervous system symptoms of headaches and confusion may occur in the acute stage. A second phase occurs during the second week of illness. The patient may have a milder recurrence of the aforementioned symptoms. This is the so-called icteric stage and may be caused by the effects of an activated immune system (90,94). Muscle pain may become severe, especially in the lower extremities. Marked conjunctival congestion (suffusion) occurs within the first few days of the illness and may persist into the second stage. Jaundice may or may not be present at this stage. Renal function worsens during this second phase, and a progressive increase in serum creatine kinase level reflects the presence of myositis. The third, or convalescent, stage starts in the third week with progressive improvement in mental status and renal function and relief from jaundice. The so-called classic Weil disease is actually a recurrence of the fever after termination of the first stage of the illness, and the initial biphasic course is bypassed. Hepatic involvement is usually self-limited, and “microcirculatory abnormalities” (95) have been implicated as a cause of high bilirubin values. One recent report from Japan (96) described a case of simultaneous hepatitis E P.1386 infection and leptospirosis, with prolonged cholestasis and jaundice lasting several months. Doxycycline may be effective prophylaxis of leptospirosis (97). Once the disease has developed, early intensive care and administration of doxycycline may be lifesaving (98), and therefore early diagnosis is important. During the first phase, leptospires can be isolated from the cerebrospinal fluid and blood; in the second phase, they are isolated from the urine. Dark-ground microscopic examination of plasma has been found to be a simple and rapid form of early diagnosis of leptospirosis with hepatorenal involvement (99). PCR based on the flaB gene of Leptospira has been found to be an efficient tool for the rapid detection and identification of Leptospira from clinical specimens (100).

Syphilis Syphilis is a multisystemic disease caused by the spirochete Treponema pallidum subsp. pallidum, and is a microaerophilic gram-negative bacterium. Like tuberculosis, syphilis, once a disease affecting primarily homosexual men, has been increasingly reported among heterosexuals in the urban areas of the United States. The disease spans several stages, from congenital involvement to tertiary disease, and derangements in liver function may occur in all stages. In the congenital form of the disease, liver manifestations generally occur between the ages of 2 and 15 years, with hepatic gummas. Biochemical hepatitis with jaundice may occur, and therefore a wide differential diagnosis can produce a diagnostic dilemma. A positive result of an ELISA test for immunoglobulin G (IgG) antibodies against treponemal antigen and the fluorescent treponemal antibody (FTA)immunoglobulin M (IgM) help establish the correct diagnosis. In a 1917 paper on the subject (101), jaundice was reported to occur in as many as 12% of cases of secondary syphilis, probably owing to inflammation of hepatocytes. The pathologic findings generally include lymphocytic and neutrophilic infiltrates in the portal tracts; pericholangiolar inflammation has also been described. Spirochetes are infrequently seen (10% in one series); identification of treponemes in the liver is even less common. Therefore, direct hepatotoxicity by the organism is probably a less likely pathogenesis of hepatitis than are immune-mediated mechanisms. Invasion of the portal venous system through the rectal portal entry in homosexual men with primary anal or rectal lesions may explain a reportedly higher frequency of syphilitic hepatitis in this population. The clinical manifestations may be subtle in an anicteric patient, who may have anorexia, weight loss, and hepatomegaly. The initial signs and symptoms may include pruritus and proteinuria (102,103). The rash of secondary syphilis usually is present, whereas the primary chancre usually is no longer present. In the absence of jaundice, biochemical cholestasis with a disproportionately increased serum alkaline phosphatase level may provide a clue to the diagnosis (104,105,106). Syphilitic hepatitis may coexist with nephrotic syndrome due to syphilitic membranous glomerulonephritis (107). However, because many of the reported cases of presumed syphilitic hepatitis occurred before the advent of viral hepatitis serologic tests, Veeravahu (105) suggested that the evidence to implicate T. pallidum as a liver pathogen in early syphilis is not convincing. Nevertheless, the occurrence of acute cholestatic syphilitic hepatitis in the era of viral hepatitis testing has been described (108). Additional laboratory studies of the syphilitic hepatitis of secondary-stage disease include a hemagglutination test for T. pallidum and an FTA absorption (FTA-ABS) test. Liver imaging studies may reveal focal liver lesions as large as 3 cm in diameter. In an unusual case from France, Maincent et al. (109) reported a case of tertiary hepatic syphilis that manifested as multinodular hepatic metastasis. This case shows that the entity of hepatic syphilis may manifest in a variety of misleading ways. Liver involvement in cases of tertiary syphilis usually is discovered at the postmortem examination. The gummas of the liver may resemble metastatic disease at autopsy or may resemble cirrhosis because of the nodular configuration of the liver in the later stages. Hepar lobatum refers to the lobulation of the liver because it appears to be divided into several smaller lobes by deep furrows. The lobulation originates from the resorption of gummas in the tertiary stages of the disease (110). Focal liver lesions with filling defects on CT scans may similarly mimic metastatic disease in a patient with weight loss. Diagnostic liver biopsy is therefore essential (109) (Fig. 50.4). Appropriate intervention with proper antimicrobial therapy may reduce the size of the liver lesions. The incidence of primary and secondary syphilis, as noted in the preceding text, has increased in the United States in recent years, especially among HIV-positive individuals (111). Regarding the involvement of the liver, the last large review of syphilitic hepatitis that was described in the medical literature was 30 years ago (112)

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until the recent report of seven such cases among HIV-infected patients (113). These individuals presented with rash and predominant alkaline phosphatase elevations, with symptomatic and biochemical improvement following antibiotic therapy. The authors noted that high rapid plasma reagin (RPR) titers were more likely to be present if CD4 + cell counts were higher. These cases emphasize the importance of entertaining the diagnosis of syphilitic hepatitis as a cause of otherwise unexplained high alkaline phosphatase levels among HIV-infected patients.

▪ Figure 50.4 Hepar lobatum. A: Diffuse pericellular sinusoidal fibrosis in congenital syphilis of liver (hematoxylin and eosin, 485×). B: Numerous spirochetes layered in periphery of sinusoids adjacent to hepatocyte cords (Dieterle, 1,200×). (Courtesy of John Watts, MD.)

P.1387

Lyme Disease One of the less recognized manifestations of multisystemic Lyme disease is hepatitis, yet hepatic involvement appears to be common. It has been suggested that Lyme disease resembles syphilis, in that a spirochete organism causes both diseases (in the case of Lyme disease, a zoonosis, the tick-borne Borrelia burgdorferi), and both diseases may develop as an acute or chronic multisystemic inflammatory disease (114). The mechanism by which liver injury occurs is not known. Direct invasion of the liver by the organism and immune-complex deposition have been proposed. In one case of Lyme disease–related hepatitis in a human, the organism was found in the liver with Dieterle staining, and the patient's condition improved with doxycycline therapy. This result suggests that borrelial invasion may cause direct hepatocyte damage (115). Lyme disease has both an early, acute stage and a chronic phase (116). Involvement of the liver is more common in the early stage. Histologic examination shows portal inflammation, ballooning of hepatocytes, considerable mitotic activity, hyperplasia of Kupffer cells, prominent microvesicular fat, and sinusoidal mononuclear and neutrophil cell infiltration (115). Clinically, in addition to other features of erythema chronicum migrans, hepatosplenomegaly and biochemical hepatitis may persist for several weeks. The acute phase may manifest as a febrile illness with jaundice and mixed hepatitic and cholestatic abnormalities (117). In a review of the cases of 115 patients with erythema migrans, the characteristic rash of early Lyme disease, approximately one third of the patients were found to have abnormal serum ALT values. Among those with early disseminated Lyme disease, two thirds of the patients had abnormal liver biochemical values (118). The investigators concluded that liver function test abnormalities are common among patients with erythema migrans but that these abnormalities are generally mild and improve with antibiotic therapy. Zaidi and Singer recently reviewed biochemical abnormalities of the liver in patients with Lyme disease (118a).

Rickettsial Infections Q Fever The causative rickettsia of Q fever is Coxiella burnetii. It was first described in Australia in the 1930s after an outbreak of an undiagnosed febrile illness among workers at an abattoir in Brisbane; the Q represents query. The source of infection is infected sheep, goats, or cattle, and the infection may be transmitted through contact with unpasteurized milk or contact with livestock. The organism has been identified in ticks, and the disease has a worldwide distribution. Liver involvement is common. The typical presentation of Q fever is a febrile, flu-like illness with pneumonitis. The usual epidemiologic risk factors of exposure to sheep, cattle, and goats may be lacking in many cases, and often the disease goes undiagnosed (119). Hepatitis is common (120), and the disease may manifest as hepatitis in the absence of pulmonary manifestations (121). In a report of 63 sporadic cases of Q fever in an urban adult population in Spain (122), approximately 50% of patients had accompanying hepatitis. Three main hepatic manifestations of Q fever have been proposed: A clinically acute hepatitis-like illness without respiratory involvement (the most common form of hepatic involvement); an incidental finding of increased liver biochemical values in a patient with known acute Q fever; or fever of unknown origin with characteristic hepatic granulomas (123,124,125). After an incubation period of 14 to 26 days, patients have a fever and flu-like symptoms, often with a dry cough. P.1388

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Bradycardia may be present. Liver biochemical abnormalities are common but nonspecific and may manifest as anicteric hepatitis. In an appropriate setting, the disease mimics several other conditions, including other fungal infections of the liver, other granulomatous diseases, drug reactions, and so on. A 70-year-old man with cancer presented with low-grade fever and fatigue following a vacation in the Canary Islands, an area endemic for Q fever. His illness progressed to jaundice and fatal liver failure; the following year, after considering the diagnosis, an indirect microimmunofluorescence test for C. burnetii IgG and IgM antibodies were strongly positive, therefore confirming acute Q fever (126). The classic doughnut granuloma of Q fever—a central clear space in the center of the granuloma—is not pathognomonic for the disease and may be seen in Hodgkin's disease and infectious mononucleosis (Fig. 50.5). The granulomas have been shown to disappear over a period of 3 months after appropriate antibiotic therapy (127). The granuloma is a dense fibrin ring surrounded by a central lipid vacuole and is composed of neutrophils, monocytes, eosinophils, and occasional multinucleated giant cells. Kupffer cells are hypertrophied and there may be a lymphocytic portal inflammation with erosion of the limiting plate (128). The disease may be prolonged, may affect children exposed to farm animals (129), and one third of patients may have jaundice. The diagnosis is established when an increase in complement fixation is detected or the result of an immunofluorescent antibody titer to C. burnetii is positive (123). PCR can be used to amplify C. burnetii DNA from tissue (130,131). Tetracycline is considered the treatment of choice, although the less effective erythromycin may be an appropriate alternative in the treatment of children. A recently developed vaccine may be efficacious in persons at high risk (132).

▪ Figure 50.5 Section shows classic doughnut granuloma. The characteristic lesion of Q fever is a doughnut granuloma similar to that shown here (hematoxylin and eosin, 780×). (Courtesy of John Watts, MD.)

Ehrlichiosis Ehrlichiosis is a rickettsial infection that occurs in animals and humans, and is caused by microorganisms of the genus Ehrlichia. The pathogenesis and comparative pathology and immunohistology of ehrlichiosis have been reviewed (133). Human infection with Ehrlichia canis, a tick-borne infection common among dogs, was first reported in 1987. Recent molecular characterization, however, has suggested that taxonomic reorganization will more accurately define the Ehrlichia species. Therefore, Ehrlichia chaffeensis causes human granulocytic ehrlichiosis, and the major tick vector is a member of the genus Ixodes (134). Involvement of the liver in human ehrlichiosis is largely anecdotal, but it can be a multisystemic disease with intense cholestasis. In one case following a documented tick bite, a 56-year-old man had multisystemic disease with sepsis and renal failure complicated by deep jaundice. Liver biopsy showed intense bile stasis and intense neutrophilic infiltration of bile ducts that suggested extrahepatic bile duct obstruction with cholangitis. A rickettsial immunofluorescent antibody panel confirmed the presence of ehrlichiosis, and the patient responded to a course of chloramphenicol (135). A tetracycline such as doxycycline also is reported to be effective. In a review of eight cases of ehrlichiosis managed at an Arkansas medical center, seven patients had raised aminotransferase levels that suggested biochemical hepatitis, and three patients had jaundice with a peak bilirubin level of 13.8 mg/dL. All eight patients were treated with and responded to doxycycline, including one patient who had multiple-organ failure but eventually recovered. The authors concluded that in the appropriate clinical setting, ehrlichiosis should be considered a cause of elevated liver enzyme values (136).

Rocky Mountain Spotted Fever Infection with the tick-borne Rickettsia rickettsii causes the multisystemic disease that is occasionally associated with an increased alkaline phosphatase level and jaundice (137). Zaidi and Singer recently reviewed the gastrointestinal and hepatic manifestation of Rocky Mountain Spotted Fever (118a).

Tick-Borne Diseases The prevalence of tick-borne diseases has been increasing in the United States as a result of greater outdoor activity and migration of the population into rural areas (118a).

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P.1389 The eight most common tick-borne diseases include Lyme disease, ehrlichiosis, Rocky Mountain spotted fever, tularemia, Colorado tick fever, tick-borne relapsing fever, Q fever, and babesiosis; many of these entities have been considered separately in this chapter. Table 50.1 summarizes the gastrointestinal and hepatic manifestations of tick-borne diseases. With the exception of Colorado tick fever and babesiosis, most of these infections may cause a form of acute hepatitis and should be considered in areas of endemicity. Ehrlichiosis is most likely to cause cholestasis and jaundice, whereas Q fever, Lyme disease, ehrlichiosis and, to a lesser extent, tularemia, may cause granulomatous hepatitis.

Table 50.1. Laboratory and Clinical Manifestations of Tick-Borne Liver Infections

Tularemia

Colorado tick fever

TBRF

Q fever

Babesiosis

+

+

+

+

+

+

++

++

++

++

+++

++

+

+

++

++

++

++

+++

++

+

+

++

++ to

++

+

++

+

+

Lyme disease

Ehrlichiosis

RMSF

Anorexia

+

++

Nausea

+

Vomiting

Abdominal pain

Manifestation

+++

Diarrhea

+

++

++

++ to +++

+

+ to ++

++

+

Hepatomegaly

R

+ to ++

+

+ to ++

R

+

+

+

Splenomegaly

+

+ to ++

+

+ to ++

R

R to +

+

+

Jaundice

+

+++

+

+

+

+

+

+ to ++

Elevated bilirubin level

+

+++

+ to ++

+

+

+

+ to ++

++ to +++

Elevated ALT level

++

++++

++ to +++

++

+

++

++ a

+

a

Elevated alkaline phosphatase level is the predominant abnormality.

ALT, alanine aminotransferase; R, rare; RMSF, rocky mountain spotted fever; TBRF, tickborne relapsing fever; +, uncommon; ++ common; +++, very common; ++++, almost always present. Reprinted with permission from Zaidi SA, Singer C. Gastrointestinal and hepatic manifestations of tickborne diseases in the United States. Clin Infect Dis 2002;34:1206–1212.

Fungal Infections Histoplasmosis Histoplasmosis has a worldwide distribution, including the central and northeastern United States, Central and South America, India, and the Far East. It is the most common cause of fungal infection in the Ohio River Valley of the United States. It is usually transmitted after inhalation of the organism Histoplasma capsulatum, which is particularly associated with bird droppings, especially those of chickens. In most cases, exposure to the fungus is asymptomatic, and documentation of previous exposure is in the form of delayed-type cutaneous sensitization. Although liver involvement is common in cases of disseminated histoplasmosis, in which case the infection may travel from the lungs to involve other organs, the disease may also present as an isolated liver mass or as an infiltrative liver disorder. A 39-year-old HIV-negative alcoholic man from New Delhi presented with a 3-month history of weakness associated with fever and jaundice. Laboratory studies showed anemia, leukocytosis, and marked alkaline phosphatase elevation. A pharyngeal culture was positive for H. capsulatum, and a liver biopsy

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showed granulomas consisting of macrophages and giant cells. Multiple periodic acid-Schiff (PAS) positive ovoid fungal bodies were seen causing a swelling of the Kupffer cells consistent with the diagnosis of hepatic histoplasmosis, and treatment with amphotericin B was started with clinical improvement. This case, with a negative chest x-ray, demonstrates the potential for isolated liver involvement in cases of histoplasmosis (138). Hepatic involvement with histoplasmosis may manifest as fever of unknown origin and cause a considerable diagnostic dilemma (139). It may also manifest as unexplained biochemical cholestasis with fatigue and weight loss, which can mimic neoplasia or even cholangitis (140). The disease occurs among persons without HIV infection, but immunosuppression in the form of chronic glucocorticoid therapy may be present. Liver biochemical abnormalities in many cases may be nonspecific, and biopsy may be needed for the correct diagnosis. Thrombocytopenia may be present and necessitate a transjugular approach to biopsy. Hepatic lesions may include diffuse granulomas distributed throughout the liver or parenchymal infiltration with macrophages filled with the organism, seen with fungal staining. One report described a rare case that presented as a solitary right-sided liver lesion invading the diaphragm (141). A review of the pathologic spectrum of cases of gastrointestinal histoplasmosis showed that 10% of 52 patients had histologic evidence of liver disease, most commonly portal lymphohistiocytic inflammation (Fig. 50.6). Discrete hepatic granulomas were found in fewer than 20% of livers that were involved (142).

▪ Figure 50.6 Elderly diabetic man who lived in an area endemic for histoplasmosis had fever and hepatomegaly. A: Confluent portal granulomas in a patient with hepatic histoplasmosis (hematoxylin and eosin). B: Special stain shows uniform, oval, yeast-like cells morphologically typical of Histoplasma capsulatum (hematoxylin and eosin, methenamine silver). (Courtesy of Laura Lamps, MD.)

P.1390 Early diagnosis may be lifesaving, so this infection requires diagnostic consideration. Management is the same as that of other disseminated fungal infections and usually includes intravenous amphotericin B. The use of newer antifungal agents has not been described. Another case of an unusual manifestation of hepatic histoplasmosis involved a 56-year-old “university lecturer” from Canada with a 10-year history of disabling fatigue, and a 6-month history of anorexia, weight loss and abnormal liver biochemistries, primarily alkaline phosphatase elevations. A liver biopsy showed non-caseating granulomas with multinucleated giant cells, and screening serologies were positive for H. capsulatum. His only risk factor was having lived in Indiana from his youth. Additional studies confirmed Addisonian crisis. After appropriate antifungal therapy, his fatigue and constitutional symptoms improved (143).

Candidiasis Caused by infection with the fungi of the genus Candida, the clinical spectrum of candidal liver disease is varied. The most common species causing human infection is Candida albicans, although other species also cause disease. Liver involvement in systemic candidiasis often goes unrecognized, and hepatic lesions may be found incidentally at autopsy. Therefore the entity of focal hepatic candidiasis may be part of the syndrome of hepatosplenic candidiasis or, more appropriately, chronic disseminated candidiasis (144), because other organ systems may be involved. Although systemic disease is presumed, results of blood cultures may be negative, and appropriate diagnosis requires a high degree of clinical suspicion. The typical patient has leukemia and fever, jaundice, and biochemical cholestasis after induction chemotherapy– associated neutropenia. After the nadir of neutropenia, the serum alkaline phosphatase level begins to increase, suggesting the presence of an infiltrative or infectious process. The pathogenesis of the disease probably relates to mucosal damage of the colonic mucosa at the time of neutropenia. Local invasion and subsequent entry of the Candida organisms into the portal circulation result in liver infection (145). Results at CT and ultrasonography are often normal in the early stage of neutropenic fever, whereas as the neutrophil count returns to normal, imaging studies may show focal liver lesions with a bull's-eye appearance (145,146,147,148) (Fig. 50.7). These lesions may be absent on images, however, even with jaundice. In such cases, diagnostic laparoscopy with local anesthesia may show discrete focal yellowish-white punctate lesions scattered throughout the liver surface (149) (Fig. 50.8). Direct-guided biopsy (Figs. 50.9, 50.10 and 50.11) may establish the diagnosis and allow for appropriate antifungal therapy. Cholangitis with common bile duct stenosis secondary to Candida colonization of the biliary tract was recently

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described in a patient on long-time mechanical ventilation. Cholangiography revealed bead-like deformity consistent with sclerosing cholangitis. Microbiologic analysis of aspirated bile confirmed Candidiasis (150). Although the diagnosis of hepatic candidiasis required histologic findings previously, confirmation by culture (not possible in formalin-fixed samples), or immunofluorescence, or PCR testing now allows for a sensitive and specific diagnosis, and further permits Candida species identification. Kirby et al. (151) described a typical case of hepatosplenic candidiasis in which PCR was positive for candida DNA in both the sera and liver biopsy. The authors noted the importance of identifying species, because candida shows species-specific antifungal resistance patterns, that is, some resistant to fluconazole and others to amphotericin.

▪ Figure 50.7 Computed tomography scan of an 8-year-old girl with leukemia undergoing chemotherapy who had a fever. Images before (top) and after (bottom) administration of contrast material reveal numerous areas of low attenuation throughout the liver and spleen. Rim enhancement of the lesions after injection of contrast material is caused by inflammation. Open biopsy of the hepatic lesion proved the diagnosis of hepatic candidiasis. (Courtesy of Ali Shirkhoda, MD.)

P.1391 Optimal therapy for hepatic candidiasis has not been established, in part because of the rarity of the condition, the paucity of controlled trials, and the absence of established end points of treatment. A relapse of the infection may be related to either premature discontinuation of therapy or inadequate antifungal treatment of patients with chemotherapy-induced neutropenia (144). Furthermore, the hepatic lesions of chronic disseminated candidiasis may transiently disappear during neutropenia, and therefore antifungal therapy should not be discontinued on the basis of radiologic findings alone (152). The original therapy for this infection consisted of amphotericin B, yet prolonged treatment with amphotericin B may cause renal toxicity and often fails to eradicate infection. Some experts have advocated the addition of other antifungal agents or the addition of liposomal formulations (153,154), which may be better targeted to enter the liver. Pappas et al. recently reviewed the treatment of candidiasis (155). Both fluconazole and caspofungin are as effective as and less toxic than amphotericin B, and can P.1392 be given orally (153,156). As illustrated in the recent case report by Kirby et al. (151), identification of the specific candida species may guide appropriate therapy, such as an oral azole, therefore obviating the need for prolonged parenteral amphotericin treatment. The heightened awareness of the entity of hepatic candidiasis in the patient with neutropenic leukemia undergoing chemotherapy has highlighted the importance of factors that promote its development, including intravenous catheters and broad-spectrum antibiotics; furthermore, there has been the suggestion that prophylactic antifungal agents may prevent systemic fungal disease, but results are conflicting (157,158).

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▪ Figure 50.8 A 60-year-old woman with leukemia had fever and jaundice after induction chemotherapy. Computed tomography scan shows no significant pathologic process. At laparoscopy, however, the liver was diffusely infiltrated with small discrete lesions of focal candidiasis.

▪ Figure 50.9 Focal hepatic candidiasis. Same patient as in Fig. 50.8 is shown here. Centrally necrotic granuloma is surrounded by a thick fibrous capsule (hematoxylin and eosin, 80×). (Courtesy of John Watts, MD.)

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▪ Figure 50.10 Focal hepatic candidiasis. Gross wedge biopsy specimen of liver shows necrotic granuloma encapsulated by fibrous tissue with central cavitation. This cavitation results in the bull's-eye lesion often seen on imaging studies. (Courtesy of John Watts, MD.)

Actinomycosis Actinomycosis is a chronic, progressive, suppurative disease caused by actinomycetes of the genus Actinomyces, notably Actinomyces israelii, Actinomyces bovis, and Actinomyces naeslundii. Infection often occurs in the mouth (cervicofacial) area, thorax, abdomen, or uterus (pelvic). Early management of dental sepsis is believed to have prevented the cervicofacial form of the disease, which is thought to cause infection by local proliferation of organisms (159).

▪ Figure 50.11 Focal hepatic candidiasis. Grocott-stained section shows numerous yeast-like cells and mycelial elements of Candida in the center of a granuloma (80×). (Courtesy of John Watts, MD.)

The involvement of the liver is rare, but primary hepatic actinomycosis is an important differential diagnosis to hepatocellular carcinoma in endemic areas, and may present as a solid liver mass. In a recent review of 57 cases reported in the literature, the mean age of patients was 43 years (range, 4–65 years) with a male predominance. Most patients presented with fever, abdominal pain and weight loss, typically with a subacute presentation of up to 18 months. Leukocytosis was common, as was serum alkaline phosphatase elevations (160). Hepatic actinomycosis had been reported to occur in 15% of abdominal cases (5% of all cases). In a review of 11 cases of actinomycosis of the liver from Japan (161), investigators found that in six cases (55%), partial hepatectomy had been performed because of involvement of liver tumors and that five patients had liver abscess. The authors concluded that hepatic actinomycosis should be considered in the differential diagnosis of pyogenic liver abscess and space-occupying lesions of the liver. The hepatic disease probably is caused by spread through the portal vein caused by a mucosal injury due to ulcer, inflammatory bowel disease, or surgery. Local aggregates of Actinomyces organisms are often associated with other bacteria, such as coliforms, and these other bacteria may be involved in the pathogenesis of the infection. The hallmark of the infection is the formation of inflammatory masses containing granules (Fig. 50.12) (162,163). The CT scan appearance may be a multiloculated low-attenuation lesion with low intensity on the T1-weighted sequence at magnetic resonance imaging (high intensity on the T2-weighted sequence) with surrounding edema. A peripherally thickened and irregular inner wall may suggest the presence of an abscess (164). Angiography may show a hypervascular hepatic mass mimicking hepatic neoplasm in the arterial phase (166,167). These radiographic features are nonspecific, however, and there is debate regarding how best to establish the diagnosis. Establishment of the correct diagnosis may be prolonged, as noted in the preceding text, because cases may

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manifest as nonspecific subacute presentations including fever of unknown origin (162,165) or inflammatory pseudotumors (163), which have the gross appearance of malignant lesions. This manifestation emphasizes the need to search for bacteria in such lesions. Often such patients have underlying sepsis due to chronic abdominal abscesses. The histologic examination of tissue samples (168) is needed to establish the appropriate diagnosis. In one case (169) a positive blood culture established the correct diagnosis, but a recent review of hepatic actinomycosis (170) observes that percutaneous or surgical interventions for tissue samples were more likely to be diagnostic than P.1393 positive peripheral blood cultures for A. israelii. In rare instances, the lesion may infiltrate the diaphragm and right lung (162).

▪ Figure 50.12 A: Microcolony of Actinomyces organisms (sulfur granule) surrounded by acute suppurative inflammation (hematoxylin and eosin, 80×). B: High-power Brown-Brenn stained section of a sulfur granule, which is composed of gram-positive filamentous bacteria. The diagnosis of actinomycosis was confirmed with direct immunofluorescence (not shown) (780×). (Courtesy of John Watts, MD.)

Most patients respond to prolonged intravenous penicillin G, alone or in combination with clindamycin or ciprofloxin, often for several months (160). Lack of response to such therapy may necessitate surgical drainage. Alternative regimens include erythromycin and tetracycline. One recent report described a 53-year-old immunocompetent male with hepatic actinomycosis who failed to respond to intravenous antibiotic and underwent right posterior hepatic segmentectomy, with successful resolution of infection and without evidence of recurrence (171).

Coccidioidomycosis The disease known as San Joaquin Valley fever is caused by the dimorphic fungus Coccidioides immitis. It is endemic in the Southwest region of the United States, Central America, and Mexico and is characterized by a respiratory infection and fever after an incubation period of 7 to 28 days. The route of infection follows inhalation of the fungus, and the disease may then spread from the primary lung focus to involve the liver. Extrapulmonary disease is rare, but case reports clearly show that both liver and biliary involvements are manifestations of coccidioidomycosis. A 26-year-old man from New Delhi had right upper quadrant pain, and ultrasonography revealed a solitary right lobe liver abscess. Aspiration of the abscess revealed pure growth of coccidioidomycosis, which was confirmed with culture (172). In the United States, 8 of 1,347 (0.59%) patients who underwent liver transplantation at a California medical center had coccidioidomycosis, showing that this organism can cause a serious and in some cases fatal infection after liver transplantation and that the incidence of this disease appears to be increasing (173). The usual clinical features are those of nonspecific anicteric hepatitis, often with biochemical cholestasis, in a person who has recently traveled to Mexico or the American Southwest. It commonly presents as a hepatopulmonary syndrome with eosinophilia (174). Biopsy of the liver shows granulomatous hepatitis (174,175). In rare instances, obstructive jaundice may relate to granulomatous involvement of the bile duct epithelium. Ramirez et al. (176) reported the case of a 43-year-old man from Arizona who had fever and abdominal pain followed by jaundice and a cholestatic biochemical profile with no obvious lung involvement. The bilirubin level reached 7.4 mg/dL, and endoscopic cholangiography showed an irregular stricture involving the common bile duct and intrahepatic biliary tree necessitating placement of a biliary stent. Biopsy of the lymph node performed at laparotomy showed granuloma with spherules, and complement fixation antibody testing confirmed the presence of coccidioidomycosis. Endoscopic retrograde cholangiopancreatography after successful therapy (fluconazole and intravenous amphotericin B) showed resolution of the stricture. Among 37 immunosuppressed patients who received liver transplants who later moved to Arizona, the incidence of new coccidioidal infection was 2.7%, suggesting that coccidioidomycosis was not frequent in this population (177). Nevertheless, among patients with end-stage liver disease listed for transplantation in this same region of Arizona, the incidence of new coccidioidal infection was 4.2%, compared with 0.04% in the same county in the general population. The authors suggested that treatment might alleviate some of the P.1394

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symptoms of coccidioidomycosis originally attributed to disease of the liver (178).

Other Infections Neisseria Nonspecific aminotransferase abnormalities occur in disseminated gonococcal infection (179,180). Cervical and pelvic gonorrhea may be associated with violin-string adhesions between the liver capsule and the peritoneal wall, known as Fitz-Hugh-Curtis syndrome. However, such adhesions are not pathognomonic for Neisseria infection, and may occur after other infections, including hepatic candidiasis (Fig. 50.13) (149).

Chlamydia A similar syndrome of perihepatitis occurs with infection with Chlamydia trachomatis (181), which may also cause prolonged fever and liver granuloma (182).

Campylobacter Mild liver dysfunction as well as acute hepatitis–like biochemical values may occur after infection with Campylobacter organisms (183). The organism has been isolated from bile during episodes of cholecystitis in association with gallstones (184).

▪ Figure 50.13 Perihepatic adhesion (Fitz-Hugh-Curtis syndrome) may occur in conditions other than gonorrhea. After therapy for hepatic candidiasis, a follow-up laparoscopy showed violin-string adhesions from the focal lesions to the peritoneal wall. Such adhesions may result in marked right upper quadrant pain.

Shigella Anecdotal case reports include a case of cholestatic hepatitis following infection with Shigella sonnei (185) and anicteric hepatitis associated with Shigella flexneri infection (186).

Yersinia Cases of granulomatous hepatitis and cholestasis have been reported in association with disseminated yersinia infections (187).

Catscratch Disease Hepatosplenic catscratch disease often manifests as fever of unknown origin in children who have had contact with an immature cat. The disease occurs when Bartonella henselae causes necrotizing granuloma in the liver or spleen or both. Fleas have also been suggested as vectors for this organism, because catscratches may be absent in some cases. Abdominal pain is common and occasionally is severe. Abdominal ultrasonography shows microabscesses in the liver or spleen. Positive serologic results for B. henselae establish the diagnosis. Several antibiotic regimens have proved effective (188). Among HIV-infected patients, a syndrome of peliosis hepatis (bacillary angiomatosis) is caused by B. henselae infection. Serologic assays, indirect immunofluorescence, and PCR assays may assist in diagnosis (189); prolonged antibiotic regimens with erythromycin, doxycycline, or macrolides have proved effective in various series (190,191).


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Alvarez SZ. Hepatobiliary tuberculosis. J Gastroenterol Hepatol 1998;13:833–839. Succinct review of the current approach to the classification, clinical spectrum, modern diagnostic techniques, and options in the management of hepatobiliary tuberculosis. El-Newihi HM, Alamy ME, Reynolds TB. Salmonella hepatitis: analysis of 27 cases and comparison with acute viral hepatitis. Hepatology 1996;24:516–519. This landmark paper from a U.S. medical center summarizes the clinical manifestations and relevance of salmonella (typhoid) hepatitis. Marrie TJ, Raoult D. Q fever: a review and issues for the next century. Int J Antimicrob Agents 1997;8:145– 161. This review article discusses all aspects of Q fever, including its historical background, thorough literature review, and clinical and diagnostic advances. The hepatic manifestations of this disease are summarized. Moseley RH. Sepsis and cholestasis. Clin Liver Dis 2004;8(1): 83–94. Comprehensive overview of recent advances in the understanding of the pathophysiology of intrahepatic cholestasis in sepsis. Mullick CJ, Liappis AP, Benator DA, et al. Syphilitic hepatitis in HIV-infected patients: a report of 7 cases and review of the literature. Clin Infect Dis 2004;39(10):100–105. Report that emphasizes the need to consider syphilis as a cause of treatable liver dysfunction in HIV-positive patients. P.1395 Zaidi SA, Singer C. Gastrointestinal and hepatic manifestations of tick borne diseases in the United States. Clin Infect Dis 2002;34:1206–1212. A practical review of the hepatic manifestations of tick borne disorders including Lyme disease.

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Copyright ©2007 Lippincott Williams & Wilkins > Table of Contents > Volume 2 > Section XI - Infectious and Granulomatous Disease > Chapter 51 - Hepatobiliary Manifestations of Human Immunodeficiency Virus

Chapter 51 Hepatobiliary Manifestations of Human Immunodeficiency Virus Neeraj Saraf Cem Cengiz James S. Park Douglas T. Dieterich

Key Concepts z

Liver disease has assumed a far greater importance as a cause of morbidity and mortality in patients infected with human immunodeficiency virus (HIV) because of their increased life expectancy as a result of antiretroviral therapy (ART).

z

Hepatobiliary disease in HIV-infected patients can be divided into two groups: Those with severe immunosuppression, who commonly have opportunistic infections, and those with suppressed HIV viral loads and minimal immunosuppression.

z

Because of shared modes of transmission, coinfection with hepatitis B virus (HBV) and hepatitis C virus (HCV) is common. HCV-related liver disease is an important cause of morbidity and mortality. HIV accelerates the natural history of HCV infection. Combination therapy with pegylated interferon and ribavirin is effective in treating these patients.

z

Hepatotoxicity associated with ART is a major cause of morbidity in HIVinfected patients. Steatosis and HIV-associated lipodystrophy are emerging as distinct entities causing liver disease in this group of patients.

z

HIV infection was earlier considered a contraindication to liver transplantation. In recent years, liver transplantation is emerging as a cornerstone in the management of end-stage liver disease in HIV-infected patients.

Since its recognition more than two decades ago, the natural history of infection with human immunodeficiency virus (HIV) has undergone a vast change, from a disease associated with high mortality, to a chronic illness that may last for decades without significant morbidity. With the introduction of antiretroviral therapy (ART) in 1996, HIV-infected patients have experienced dramatically prolonged survival, resulting in patients falling sick from comorbidities unrelated to HIV. Liver disease has become one of the most important factors affecting survival, quality of life, and health care costs among HIV-infected patients. HIVinfected patients experience an array of hepatic manifestations (Table 51.1).

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Given the shared epidemiologic risks, patients with HIV are commonly coinfected with hepatotropic viruses, and in particular coinfection with hepatitis C virus (HCV) which is now the leading cause of liver disease in HIV-infected patients in developed nations. Hepatotoxicity associated with ART also contributes significantly to liver disease in HIV-infected patients. In recent years, with the effective use of ART, opportunistic infections have assumed a lesser role in contributing to liver disease, although they are still an important cause of morbidity in developing countries. Steatosis and HIV-associated lipodystrophy are now being considered as distinct entities in this group of patients. Hepatic manifestations of HIV-infected patients without significant immunosuppression result from coinfection as with other hepatotropic viruses. The natural history, pathogenesis, and management of the hepatitis viruses in the presence of HIV infection are discussed in the subsequent text.

Table 51.1. Major Causes of Liver Injury in HIV-Infected Patients

DRUGS ART: NRTI, NNRTI, PI Antimicrobial agents: Antituberculosis (INH, rifampin) Macrolides (clarithromycin, azithromycin) Antifungal (ketoconazole, itraconazole, fluconazole) Antipneumocystis (TMP-SMX, pentamidine, dapsone) INFECTIONS Viral (HAV, HBV, HCV, HDV, GBV-C, CMV, HSV, VZV, EBV) Mycobacterial (Mycobacterium avium, Mycobacterium tuberculosis, other mycobacteria) Fungal (cryptococcus, histoplasma, coccidioides, candida) Protozoan (pneumocystis, toxoplasma, microsporidia, cryptosporidium) BILIARY TRACT INFECTIONS HIV cholangiopathy Acalculous cholecystitis NEOPLASMS AND VASCULAR LESIONS Kaposi sarcoma Lymphoma Peliosis hepatis STEATOSIS WITH LIPODYSTROPHY HCV/HIV coinfection Drug-associated (PI and NRTI)

ART, antiretroviral therapy; NRTI, nucleoside reverse transcriptase inhibitors; NNRTI, non-nucleoside reverse transcriptase inhibitors; PI, protease inhibitor; INH, isonicotonic acid hydrazide; TMP-SMX, trimethoprim-sulfamethoxazole; HAV, hepatitis A virus; HBV, hepatitis B virus; HCV, hepatitis C virus; HDV, hepatitis D virus; GBV-C, hepatitis G virus; CMV, cytomegalovirus; HSV, herpes simplex virus; VZV, varicellazoster virus; EBV, Epstein-Barr virus; HIV, human immunodeficiency virus.

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P.1402

Hepatitis B Virus Because of common epidemiologic risks of transmission including sexual and parenteral exposures, coinfection of hepatitis B virus (HBV) with HIV is common. Coinfection rates vary by risk factors, geographic region, and endemicity, being the highest among men who have sex with men (6% to 10%) in developing countries (1,2,3). As a consequence, up to 80% of HIV-infected patients have serologic markers of present or past HBV infection (hepatitis B surface antibody [anti-HBs] or hepatitis B core antibody [anti-HBc] positive) and 10% to 15% are chronic HBV carriers (hepatitis B surface antigen [HBsAg] positive) (2,3,4). Decreased response to HIV-ART and a higher risk of hepatic decompensation was observed in HBV/HIV-coinfected patients compared with those of HIVmonoinfected patients (5). Chronic liver disease because of viral hepatitis has emerged as one of the leading causes of mortality and morbidity in HIV-infected patients in the post-ART era (6).

Immune Dysfunction in Human Immunodeficiency Virus and Hepatitis B Virus Coinfection Immune dysfunction related to HIV infection affects the natural history of HBV infection, reflecting the fact that the immune response plays a key role in viral clearance and the hepatic damage associated with HBV infection (7). Cytotoxic CD8+ lymphocytes recognize HBV antigens in the context of human leukocyte antigen (HLA) class I antigen exposed on the surface of infected hepatocytes and destroy them. During clearance of virally infected cells, CD8+ lymphocytes, with CD4+ help, mediate destruction of infected hepatocytes with resultant transaminitis and histologic damage (8). As the CD4+ lymphocytes are crucial for effective CD8+ cell-mediated immunity (CMI), depressed CD4+ cell number and function caused by HIV-mediated destruction will modify the natural history of HBV infection. This is illustrated by the finding that increased risk of chronic infection appears to be inversely correlated with the CD4+ cell count and is likely a result of the inability to promptly and vigorously respond to HBV antigen (9). The importance of the CD4+ cells in the control of HBV is also illustrated by the finding that improvement of HIV-infected patient's immune response with ART may induce spontaneous e antigen (hepatitis B e antigen [HbeAg]) to e antibody (hepatitis B e antibody [HbeAb]) seroconversion of their chronic HBV infection (9). On the other hand, ART-induced immune reconstitution may also be associated with acute hepatitis, presumably because of increased recognition and destruction of HBV-infected hepatocytes (7,10). Decreased anti-HBV immune surveillance resulting from HIV also results in heightened HBV replication, manifested by higher levels of HBV-DNA, higher rates of reactivation of HBV infection, increased HBeAg titer, and a lower rate of spontaneous HBeAg seroconversion (9,11). Despite higher serum HBV-DNA levels, hepatic necroinflammation tends to be milder in HBV/HIV-coinfected individuals (12) that is in agreement with the postulated immune-mediated pathogenicity of HBV. However, the enhanced replication levels of HBV in HIV-coinfected patients may result paradoxically in the progression of liver fibrosis and increased mortality (11). Consistent with this observation, several clinical studies have shown that the risk of end-stage liver disease is significantly increased in HIV-infected patients with chronic hepatitis B, especially those with low CD4 cell counts (1,2,3,4,5). The diminished immune responses in HIV-infected individuals may enhance a persistent HBV coinfection through covalently closed circular DNA (cccDNA) that

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replicates in the cytosol of infected hepatocytes (8). The P.1403 term “occult HBV infection” was recently coined to define the presence of HBV DNA in the serum or liver of patients without HBsAg (13). The results of previous studies of occult HBV infection in HIV-infected patients are controversial. Earlier studies have shown high rates of occult infections (14,15). However, recent studies have found very low level ( Table of Contents > Volume 2 > Section XII - Elements of Liver Transplantation > Chapter 53 - Selection and Timing of Liver Transplantation

Chapter 53 Selection and Timing of Liver Transplantation Richard B. Freeman Jr.

Key Concepts z

Selection of candidates for liver transplantation is not necessarily linked to the timing of liver transplantation due to the severely constrained organ donor resource. This means that individual candidates cannot always receive a transplant at the optimal time for his or her benefit.

z

For most patients with chronic liver disease, selection for transplantation depends on their risk of dying from the liver disease weighed against their risk of dying from the transplantation procedure and attendant medications. Mortality risk scores have been helpful in determining when this risk of death without transplantation is greater than the risk after the procedure. Although patients with severe chronic liver disease have deteriorated health-related quality of life (HRQOL), this must be weighed carefully against the risk of death while waiting compared with the risk of death from the transplantation. There can be no quality of life for deceased candidates.

z

For some liver conditions, the benefit of liver transplantation cannot be weighed against the mortality risk from intrinsic liver disease. Therefore other methods, such as estimates of disease progression, must be used for proper selection of waiting candidates. Disease progression estimates are limited by lack of good natural history data.

z

Pediatric patients with liver disease face unique problems and mortality risk models utilizing variables specific for children have been developed to address these differences.

z

Efficient selection of liver transplantation candidates with acute liver failure is especially challenging because of the need to rapidly assess the probable natural course of the disease so that patients not likely to recover will receive transplant priority but those more likely to recover do not receive needless transplants.

z

Living donor liver transplantation improves the ability of the clinician to “time” the transplantation at the most advantageous point in disease progression for the waiting candidate. However, donor risks and informed consent must not be subjugated in an effort to maximize the timing benefit.

Inhabitants in the developed world are fortunate that, in large measure, effective treatments for most medical conditions are generally available with access to these treatments limited mostly by socioeconomic or distributive problems, rather

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than scarcity of the therapeutic substrate itself. This is not the case for transplantation. Unlike any other field in medicine, the clinician's ability to apply transplantation therapy is not completely defined by the risk-benefit ratio of that therapy for the patient in question. For patients who could potentially benefit from liver transplantation, the constrained resource problem is acutely severe because alternative liver support technologies are not perfected. Therefore, the application of liver P.1454 transplantation therapy, depends not only on the diagnosis of a problem for which liver transplantation is likely to provide more benefit than harm, but also on the availability of the therapeutic substrate; the liver itself. Consequently, and in contrast to most other medical conditions, determining if a patient diagnosed with progressive liver disease will receive benefit from liver transplantation is not sufficient for initiation of delivery of the treatment. This makes the optimal timing for liver transplantation a two-sided proposition: (a) Determining when a patient's disease has advanced far enough that he or she will receive more benefit than harm from the transplantation procedure and subsequent maintenance treatments, and (b) determining who, among all those who are deemed to likely receive benefit, should come first when donor constraints allow only one patient at a time to be treated. The former patient-based issue can be categorized as selection of appropriate candidates for transplantation. The second topic, timing of liver transplantation, is not entirely under the control of the treating physician or patient but much more influenced by allocation and distribution rules. Only in the case of living liver donor transplantation, can treating clinicians completely control the timing of liver transplantation for candidates they have deemed appropriate. In this chapter, the selection of patients for liver transplantation, the optimal timing of liver transplantation, absent organ donor constraints, the timing of liver transplantation in the context of living donor liver transplantation, and finally organ allocation priorities and their influence on the timing of liver transplantation are addressed.

Selection of Candidates for Liver Transplantation Mortality Risk Liver transplantation, like all therapies, should be offered when the risks are outweighed by the benefits. Quantitating risk and benefit however, is no easy proposition, and fraught with subjective interpretations of need for transplantation. For any candidate, comorbid conditions, such as cardiopulmonary disease (1), renal function, chronic or active acute infections, neurologic and psychiatric impairments as well as the social support system available to the patient must be assessed and considered in the overall determination of surgical risk. Caregivers and patients must weigh mortality risks, disease progression, and the impact of deterioration in quality of life for patients with liver disease who may be candidates for liver transplantation. In the past, most patients were deemed reasonable candidates for transplantation based on the development of signs or symptoms of decompensation usually related to portal hypertension (2). These original assessments of liver transplantation candidacy were subsequently incorporated into minimal listing criteria based on an anticipated 1-year survival of 90% or less if no transplantation was performed (3). This 1-year waiting list survival criterion was equated to a Child-Turcotte-Pugh (CTP) (4) score of greater than or equal to 7. However, the use of subjective variables, and differences in cholestatic versus noncholestatic liver diseases, as well as a “ceiling effect”

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inherent in the CTP score for more advanced chronic liver disease, led investigators to develop mathematical models for primary biliary cirrhosis (5,6,7,8,9), and primary sclerosing cholangitis (10) to predict mortality. Subsequently, these models were compared to the CTP score and found to have similar accuracy for prediction of mortality risk (11). More recently, Malinchoc et al. defined a mathematical model to predict mortality risk in any patient with portal hypertensive complications undergoing transjugular intrahepatic portosystemic shunt (TIPS) procedure regardless of the underlying chronic liver disease (12) and without using the subjective variables employed by the CTP score (Table 53.1). This so-called Model for End-Stage Liver Disease (MELD) score has subsequently been shown to be highly predictive of 3-month mortality for a variety of cohorts of patients with chronic liver disease (13,14) and for a cohort of US patients waiting for liver transplantation (15). The MELD model has been widely accepted as a measure of chronic liver disease severity where severity of disease is defined as 3-month mortality risk and has been adapted to be incorporated into US liver allocation policy for determination of priority on the waiting list (16) (Fig. 53.1 and Table 53.1). Therefore, if one defines the need for liver transplantation in terms of risk of dying of liver disease, the MELD score provides an objective, readily available, easily applied, measure for selection of liver transplantation candidates with chronic liver disease.

▪ Figure 53.1 Plot of Model for End-Stage Liver Disease (MELD) score at listing versus survival fraction for new listings on the liver transplantation waiting list 15 September, 2001, to 15 February, 2002.

Table 53.1. Model for End-Stage Liver Disease Score and Pediatric EndStage Liver Disease Score

A. Malinchoc et al. (12) R = 0.957 × log e (creatinine mg/dL) + 0.378 × log e (bilirubin mg/dL) + 1.120 × log e (INR) + 0.643 × (disease etiology a ) B. MELD score UNOS/OPTN Policy R = (0.957 × log e (creatinine mg/dL) + 0.378 × log e (total bilirubin

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mg/dL) + 1.120 × log e (INR) + 0.643) × 10 PELD score R = (0.463 (age b ) – 0.687 × log e (albumin g/dL) + 0.480 × log e (total bilirubin mg/dL) + 1.857 × log e (INR) + 0.667 (growth failure c )) × 10 MELD score as originally reported by Malinchoc et al. (12) (A), and as modified for US organ allocation (B). PELD score as reported by McDairmid et al. (17) and as is currently used for US pediatric liver allocation policy.

a

1 for noncholestatic disease, 0 for cholestatic disease.

b

2 standard deviations below the mean for age = 1, ≤2 standard

deviations below the median for age = 0. MELD, Model for End-Stage Liver Disease; INR, international normalized ratio; UNOS, United Network Organ Sharing; OPTN, Organ Procurement and Transplantation Network; PELD, pediatric end-stage liver disease.

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Health-Related Quality of Life Mortality risk, however, may not be the only measure of need for liver transplantation. Numerous studies have documented that health-related quality of life (HRQOL) is poor for patients with progressive chronic liver disease (18,19,20) and that measures of mortality risk may not necessarily correlate with measures of HRQOL for these patients (21). Nonetheless, when weighing qualityof-life considerations physicians must account for mortality risk because, for patients who die, there can be no quality of life. Therefore, mortality risk usually takes precedence in determining the appropriate timing of liver transplantation for individual patients when the risks of death from transplantation surgery and immunosuppression are relatively low in relation to the mortality risk without transplantation although the patient's quality of life may be poor (22). For example, offering liver transplantation to patients with limitations in their HRQOL, who face a higher risk of dying because of the surgery and posttransplantation treatments than they will if they wait until their disease becomes more severe, may not be in their best interest. However, in one study of patients with end-stage liver disease, the subjects were frequently willing to accept a reduction in life expectancy in return for improved health and one half of the subjects accepted a 50% mortality risk in exchange for perfect health (23). Interestingly, almost all studies have shown significant improvements in HRQOL after transplantation (24), and the HRQOL outcome is not associated with the severity of illness before transplantation (25,26,27). Therefore, regardless of how ill patients are before the transplantation, if they survive, most can expect a reasonable HRQOL or functional status (Fig. 53.2). Therefore, there does not seem to be a justification for selecting one group of patients for liver transplantation because they are likely to achieve a better HRQOL afterwards than another group of patients. The available literature suggests that all recipients report relatively similar and significantly improved HRQOL afterwards.

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Transplantation Benefit The concept of selecting patients on the basis of estimates of transplantation benefit, as measured in number of life-years gained, has been recently addressed. Merion et al. compared the mortality risk for liver transplantation candidates remaining on the list with mortality risk for recipients of deceased donor liver transplants (DDLTs) and stratified their results by MELD score on listing. These investigators found that recipients with MELD scores less than 15 experienced a higher hazard for death than the candidates who remained on the list without transplantation at 1 year of follow-up. The authors concluded that, “liver transplants are being performed for some candidates who have a higher risk of dying from the transplantation procedure than they have from dying from their underlying liver disease” (29) (Fig. 53.3). P.1456 It is interesting to note that in this study there was no MELD score beyond which a benefit in survival was obtainable. Therefore, even for candidates with very high pretransplantation mortality risks, as defined by their MELD scores, a significant benefit is achieved by liver transplantation because the success rate is still acceptable and their survival probability without transplantation is essentially zero. However, the post-transplantation survival results are based only on the candidates for whom liver transplantation was performed, and many more patients with high MELD scores than those with lower MELD scores are removed from the waiting list for reasons of death or being too sick (30). These results indicate that there is a selection process by which centers are choosing candidates with high MELD scores for whom they expect a good chance of success. From these data, the optimal timing of liver transplantation for patients with chronic liver disease can be estimated on the basis of their mortality risk, as defined by their MELD score. Most patients with nonmalignant liver disease, who have MELD scores greater than 15, will receive a benefit from liver transplantation, whereas those with lower MELD scores have a better chance of surviving for 1 year without transplantation.

▪ Figure 53.2 Karnofsky performance scores for patients before and at various times after liver transplantation. Patients with poor baseline scores (solid line) had similar performance scores after transplantation compared with patients with less severe performance scores (dotted line) (28). (From Pinson CW, Feurer ID, Payne JL, et al. Health-related quality of life after different types of solid organ transplantation. Ann Surg 2000;232(4):597–

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607.)

▪ Figure 53.3 Comparison of mortality risk expressed as hazard ratio by Model for End-Stage Liver Disease (MELD) score for recipients of liver transplants compared to candidates on the liver transplantation waiting list. (From Merion RM, Schaubel DE, Dykstra DM, et al. The survival benefit of liver transplantation. Am J Transpl 2005;5:307–313.)

More recently, several reports have suggested that there are diagnostic groups of patients with chronic liver disease for whom MELD may not accurately reflect mortality risk. Patients with human immunodeficiency virus (HIV) and hepatitis C virus (HCV) coinfection (31), patients with intestinal failure (32), and perhaps patients with severe ascites (33) may have higher mortality risks than their MELD score defines. Future refinements in mortality risk models with concerted collection of natural history data for these patients will be required to improve the selection of patients with these conditions for transplantation. Overall, for individual patients with severe symptoms or poor HRQOL but low mortality risks, the decision of performing transplantation must be carefully weighed by the treating physicians to determine whether there is sufficient justification to accept the greater hazards of death for potential improvement in HRQOL.

Other Disease Progression Endpoints For some patients with liver diseases treatable by transplantation, mortality or HRQOL risk may not be the correct metrics by which need can be judged. Examples of such conditions are hepatocellular cancer (HCC), metabolic liver

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diseases, hepatopulmonary syndrome (HPS) and portopulmonary hypertension (PPH) syndrome. Patients with these disorders usually do not have significant mortality risks from their underlying liver disease but face risks of disease progression beyond a point at which liver transplantation can be offered with a reasonable chance of success. Unfortunately, risk models for disease progression for these P.1457 conditions have not been derived, making evidence-based selection problematic.

Hepatocellular cancer Because HCC is increasingly recognized as a worldwide health problem (34), much more attention has been focused on its natural history and treatment. Liver transplantation was originally attempted to treat patients with extensive unresectable HCC (35). More recently excellent short- and longer-term results have been achieved with liver transplantation for patients with small HCC lesions arising in cirrhotic livers. Specifically, patients with cirrhosis and a single HCC lesion less than 5 cm in diameter or three or fewer lesions, the largest of which is less than 3 cm in diameter—the so-called Milan criteria—(36) (Fig. 53.4), have 4year survival rates in excess of 80%, which are comparable to liver transplant recipients with nonmalignant primary liver diseases (37) and better than those undergoing surgical resection (38). These excellent results are dependent on the timing of transplantation in patients before the tumor extends to a larger size and/or disseminates. Therefore, selection of appropriate candidates with HCC for liver transplantation depends on the development of prognostic models of tumor progression. Investigators from Barcelona pointed out that the time spent waiting for a deceased donor liver was the most important determinant of HCC progression P.1458 beyond the Milan criteria (39), and it was subsequently found that application of adjuvant local treatment to HCC lesions for candidates waiting for transplantation for more than 1 year is a cost-effective strategy for maintaining these patients’ candidacies within the Milan HCC criteria (40). More recent single-center studies have suggested that the probability of progression for HCC tumors that are less than 3 cm in size is approximately 10% within 1 year after listing, whereas larger tumors have an approximately 60% chance of progressing beyond the Milan criteria within a year of listing (41) (Fig. 53.5). Additional studies have been published indicating that lesions slightly beyond the Milan size criteria may have similar long-term results after transplantation (42,43,44), but these have not yet been confirmed in larger multicenter reports.

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▪ Figure 53.4 Correlation of post-transplantation pathologic confirmation of early stage hepatocellular carcinoma with overall survival (A) and recurrence-free survival (B) among 48 patients with cirrhosis. Data on the three patients who died within 1 month of transplantation were included in the calculation of recurrence-free survival. Before transplantation, all the patients were estimated to have either a single hepatocellular carcinoma 5 cm or less in diameter or no more than three tumors, each of which was 3 cm or less in diameter. After transplantation, the explanted livers were examined pathologically, and the patients whose tumors actually met the predefined criteria were compared with those whose tumors did not meet those criteria. Ninety-five percent confidence intervals (bars) are shown at 1-year intervals. (From Mazzafero V, Regalia E, Doci R, et al. Liver

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transplantation for the treatment of small hepatocellular carcinomas in patients with cirrhosis. N Engl J Med 1996;334:693–699.)

For patients with HCC but minimal or no underlying liver disease, liver transplantation remains controversial. Some recent reports suggest that for patients with HCC and mild liver disease within CTP class A, long-term patient survival rates are improved with liver transplantation compared with liver resection (45). However, because of reasonable success for resection (46,47) and scarcity of organ donors, in addition to good success rates reported for salvage transplantation in patients with recurrent HCC after surgical resection (48), most authors advise surgical resection or ablation as a first-line treatment for HCC in patients with well-compensated liver disease (49,50). Diagnostic accuracy for HCC, however, confounds the optimal timing of liver transplantation for these candidates. Many recent studies have shown that screening high-risk populations for HCC and subsequent confirmatory computed tomography (CT) or magnetic resonance imaging (MRI) can achieve sensitivity and specificity of 70% to 80% at best (51,52,53). The accuracy of imaging tests is further reduced for lesions less than 2 cm in size (52). Liver biopsy has been advocated to overcome some of these problems (54), but risks of bleeding, needle tract seeding by tumor, and sampling errors have limited its widespread use (55). Liver transplantation for patients with false-positive diagnoses of HCC who otherwise do not have severe underlying liver disease exposes these patients to increased surgical and immunosuppressive risks relative to medical management and diverts scarce organs away from those who could benefit more (See “Timing of Liver Transplantation in the Context of Liver Allocation”).

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▪ Figure 53.5 Probability of removal from the transplantation waiting list according to initial size of hepatocellular cancer tumor, comparing tumors presenting with more than 3 cm in size (solid line) with tumors 3 cm or less in size (dashed line). (From Yao FY, Bass NM, Nikolai B, et al. A follow-up analysis of the pattern and predictors of dropout from the waiting list for liver transplantation in patients with hepatocellular carcinoma: implications for the current organ allocation policy. Liver Transpl 2003;9:684–692.)

The available evidence suggests that patients with documented HCC within the Milan criteria who are otherwise acceptable liver transplantation candidates should be selected for the procedure. Diagnostic inaccuracy compels caregivers to confirm the diagnosis with complementary modalities (56). In the future, improved genomic or proteomic testing may be widely available and provide much more accurate diagnostic (57,58) and prognostic (44) information to optimize selection of patients for surgical resection or transplantation.

Pulmonary syndromes Some patients with chronic liver disease develop pulmonary symptoms that impair their HRQOL and increase their risk for surgical intervention (59). These patients may or may not have severe intrinsic liver disease (60) and may not have advanced CTP or MELD scores (61). HPS defines a constellation of symptoms including dyspnea, hypoxia, reduced diffusing capacity of lungs for carbon monoxide (DLCO), and increased pulmonary arteriovenous shunting in the presence of chronic liver disease. Although there are no large-scale studies to adequately define mortality risk or even P.1459 precisely define the disease, most practitioners agree that patients with severe HPS have increased risk of death beyond that predicted by their MELD score and that they face increased operative morbidity, length of hospital stay, and transplantation procedure mortality (60,62). Results for patients selected for transplantation have been acceptable, with most patients experiencing improvement or resolution of their pulmonary condition (60,62). For these reasons, patients with signs and symptoms of HPS who do not have severe pulmonary hypertension should be considered for transplantation before their pulmonary function deteriorates to a point where anesthetic and surgical risks

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become prohibitive. Individuals with cirrhosis can also present with pulmonary hypertension or socalled PPH. In some cases these patients are asymptomatic, and their increased pulmonary resistance is discovered only at the time of invasive monitoring for the transplantation procedure. Patients with PPH have an increased mortality risk, above that expected from their underlying liver disease, and increased perioperative cardiovascular mortality has been reported for patients with elevated pulmonary artery pressures who undergo liver transplantation (62,63). Nonetheless, many of these cases can be managed effectively and outcomes for selected candidates, although sparsely reported, have been reasonable (62,64). These patients have to be carefully selected with multidisciplinary evaluation by transplantation hepatology, pulmonology, anesthesiology, and surgical specialists. Patients with elevated pulmonary artery pressures who respond to intravenous prostaglandin treatment have better results with liver transplantation than those who do not, making a trial of prostaglandin treatment a reasonable diagnostic and therapeutic choice before selection for transplantation (65,66). At this time, the available literature suggests that patients with moderate PPH or those who respond to prostaglandin treatment should be selected for liver transplantation because their outcomes are acceptable and transplantation may improve their PPH (67) afterward.

Metabolic liver diseases Individuals with metabolic liver disease may also have legitimate indications for liver transplantation but may not have significant synthetic liver failure. Diseases such as Wilson disease, porphyria-induced liver disease, hemochromatosis, cystic fibrosis, and α 1 -antitrypsin disease generally cause cirrhosis, portal hypertension, and hepatic synthetic failure. Consequently, mortality risk and existing measures of HRQOL should function well for these patients because they can be selected for transplantation using a mortality risk–based need for transplantation, defined by their intrinsic liver disease. However, patients with conditions such as familial amyloid polyneuropathy (FAP), hereditary oxalosis (HO), and inborn errors of hepatic metabolism, such as urea cycle defects, Crigler-Najjar syndrome, tyrosinemia, and other rare enzymatic diseases, may not develop hepatic fibrosis, portal hypertensive symptoms, or deterioration in hepatic synthetic function, as is normally captured by measurements of bilirubin levels, coagulation factors, or albumin synthesis, or assessment of portal hypertensive signs and symptoms. Nonetheless, particularly for metabolic defects that are intrinsic to the liver, liver transplantation has offered excellent short- and long-term results for properly selected individuals. The prime factor in selecting these patients for transplantation is whether the effects of the disease will be reversed by liver transplantation regardless of the anatomic location of the metabolic defect. In adults, the best example of such a condition is FAP, in which the enzymatic defect usually occurs in an otherwise normal liver but causes severe systemic problems because of deposition of a mutant transthyretin (TTR) protein. Deposition of these fibrils in neurologic, cardiac, gastrointestinal, and urinary tissues results in progressive loss of function and an untreated median survival of 9 to 13 years (68). Liver transplantation restores normal TTR synthesis, with disappearance of the mutant protein from the blood of affected recipients and slowing or partial resolution of symptoms in successful cases (69,70). Therefore, the extent of secondary manifestations of FAP at the time of presentation, especially myocardial dysfunction and progressive neuropathy, limits successful

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recovery after liver transplantation. Optimal selection of liver transplantation candidates with FAP requires early identification and assessment of the severity of end-organ involvement so that the candidate has sufficient cardiopulmonary reserve to survive the surgery and before these complications become so debilitating that they are irreversible. In some cases, the end-organ disease does not improve after restoring normal TTR synthesis with transplantation (68). In children, patients with primary hyperoxaluria type 1 (PH-1), develop severe renal calculi and resultant renal failure, but the metabolic defect resides in the alanine glyoxylate aminotransferase gene that is exclusively expressed in hepatic peroxisomes. Therefore, liver transplantation cures the enzyme defect because the deficient genes are replaced by the transplantation of the normal liver, although established renal damage does not resolve after liver transplantation. Therefore, most patients with PH-1 are selected for liver transplantation after conservative measures have failed and renal disease has progressed. Consequently, many patients with PH-1 are treated with combined liver–kidney transplants (71). Preemptive liver transplantation, performed before renal complications have P.1460 progressed, has been advocated for patients with PH-1 (72), but the morbidity and mortality risks incurred by liver transplantation and immunosuppression must be considered carefully for these minimally symptomatic patients with relatively preserved renal function who may enjoy a good HRQOL and survival with conservative management for many years (73). Other examples of diseases intrinsic to the liver are the urea cycle disorders (74,75), other hyperammonemic syndromes (76,77), maple syrup urine disease (78), and hereditary tyrosinemia type 1 (79), in which defects cause extremely elevated ammonia levels, neurologic disease, and coma, all of which can be reversed with liver transplantation if recognized early. In some cases, the neurologic consequences of these diseases progress to a point where they cannot be reversed by liver transplantation (75), making early recognition of these diseases the most critical aspect in selection of patients with these conditions for liver transplantation.

Pediatric Considerations As alluded to in the preceding text, selecting children for liver transplantation is complicated by the fact that growth retardation, delayed development, and neurologic impairment are all deleterious sequelae of many of the liver diseases and metabolic disorders presenting in childhood. There is evidence that liver transplantation can help reverse some of the growth retardation (80,81) and developmental delays (82), but not completely (83,84,85). For these reasons, pediatricians have emphasized the need to select children for liver transplantation at a stage early enough in their disease that will provide a reasonable chance for some catch-up growth and development (83,86). There are several studies suggesting that children who receive transplantation have good HRQOL afterward (85,87), but these desirable outcomes must be weighed against the mortality risks of the surgery and immunosuppression because children who do not survive the transplantation procedure cannot possibly achieve catch-up growth, accelerate their development, or improve their HRQOL. Mortality risk factors for children with liver disease differ from mortality risk variables in adults. The Pediatric End-Stage Liver Disease (PELD) score (Table 53.1) utilizes bilirubin level, international normalized ratio (INR), albumin level,

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age, and growth failure factors to predict 3-month mortality with reasonable accuracy in patients younger than 19 years (17). Other prognostic scores such as the Wilson Disease Index employ white blood cell count and serum AST levels in addition to albumin, bilirubin, and INR values (88). Because children often present with diseases for which liver transplantation can be beneficial but without intrinsic liver synthetic failure, such as metabolic diseases discussed in the preceding text, selection of these candidates requires early diagnosis and identification of extrahepatic manifestations before they become irreversible.

Acute Liver Failure Acute liver failure, also known as fulminant hepatic failure (FHF), remains a vexing and lethal clinical problem for pediatric and adult liver specialists. The diverse etiologies and difficulty in predicting which patients will recover spontaneously and those who will die without timely liver transplantation contribute to the complexity of selecting these patients for transplantation. Liver transplantation remains the best option for long-term recovery, but predicting who will recover without liver transplantation and who will not remains the critical issue for clinicians caring for these patients. Several prognostic scores have been developed to assist in decision making in this regard. The King's College group (89) and a French group (90) each published models for the prediction of death from acute liver failure (Table 53.2). Both these models have excellent positive predictive value for determining which patients will die from acute liver failure, but in subsequent studies both models have been shown to have relatively low negative predictive value (91,92,93). Although it may be desirable to err on the side of transplantation when the consequences of the failure to perform transplantation in a patient destined to die of liver failure are so extreme, the use of these models can result in inappropriate utilization of donor organs for patients who would otherwise recover without engraftment. More recently, in a study in which patients with acetaminophen toxicity were excluded, the MELD score was shown to have a superior positive and negative predictive value and a higher concordance for predicting which patients would die and which would recover with acute liver failure (94). These results have been further supported by a recent study of the US liver transplantation database in which the MELD score for patients with non–acetaminophen-induced acute liver failure was highly predictive of P.1461 mortality risk (95). Prognostic indicators for early mortality in patients with acetaminophen toxicity such as acetaminophen plasma half-life levels (96), coagulation factor levels (97), Gc protein levels (98), Acute Physiology and Chronic Health Evaluation (APACHE) II score (99) or phosphate levels (100), or addition of serum lactate (101) to the King's College models have been reported, but a recent meta-analysis found that these prognostic models have limited sensitivity and specificity, making them of questionable usefulness in the selection of patients with acetaminophen-induced liver failure for transplantation (102) (Table 53.3).

Table 53.2. King's College and Clichy Criteria for Liver Transplantation

King's College criteria INR >6.5 or any three of the following:

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Age 40 y Etiology: Drug toxicity or viral hepatitis Duration of jaundice before onset of encephalopathy >7 d INR >3.5 Bilirubin >17.5 mg/dL Clichy criteria Portosystemic encephalopathy Factor V: 300 µmol/L + encephalopathy grade ≥3. PT, prothrombin time; APACHE, Acute Physiology and Chronic Health Evaluation. From: Bailey B, Amre DK, Gaudreault P. Fulminant hepatic failure secondary to acetaminophen poisoning: a systematic review and metaanalysis of prognostic criteria determining the need for liver transplantation. Crit Care Med 2003;31(1):299–305.

Accurate prognostic information is essential for selection of patients with acute liver failure for transplantation. The King's, Clichy, and perhaps the MELD score may be helpful tools for patients with non–acetaminophen induced fulminant failure, but their low negative predictive value should be kept in mind. Selection of patients with acetaminophen-induced liver failure remains more problematic, and careful clinical observation for encephalopathy and trends in hepatic synthetic function remain indispensable in selection of these patients and all those with acute liver failure.

Timing of Liver Transplantation Living Donor Liver Transplantation The advent of living donor liver transplantation in the late 1980s for children (103) and early 1990s for adults (104) introduced the possibility of electively timing liver transplantation. With this innovation, it became possible for patients with liver disease treatable with liver transplantation who are fortunate enough to have a suitable and willing donor to receive their transplant at a point where the risks of the surgery are outweighed by the risks of not performing the transplantation. This was the main justification for application of living donor liver transplantation to children (105) because pediatric deceased donor organs are even more scarce than adult organs and, as discussed previously, the timing of transplantation for children may not always be best estimated by mortality risk derived from the intrinsic liver disease. Patients selected for living donor liver transplantation have included children with most indications for liver transplantation, including acute liver failure, and adults with HCC (106,107) and other conditions that do not consistently receive enough priority on the waiting list. In general, for nonacute cases, living donor liver transplantation has been reserved for patients with less severe liver disease, and estimations of mortality risk can be helpful in selecting candidates who will derive benefit from the transplantation but who do not carry extreme post-transplantation mortality risks (108). A report from Japan used the MELD score to identify candidates who could receive the smaller left-lobe graft and still achieve an acceptable outcome (109). Controversy remains about the utility of living donor liver transplantation for patients with hepatitis C, with some reports suggesting more frequent and rapid recurrence (110,111) and others finding no difference (112,113) in recurrence rates compared with deceased donor grafts (Fig. 53.6). Although there are limited reports of living donor liver transplantation being

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performed for acute liver failure in adults (114), most clinicians would reserve the living donor procedure for patients with moderately severe chronic liver disease, in which there is sufficient time for a complete donor evaluation and informed consent without the added coercion of an acute, potentially immediate fatal liver disease in the recipient candidate. Conversely, living donor liver transplantation for pediatric candidates, in which an adult donor donates a P.1462 smaller portion of his or her liver and thereby faces a lower operative risk, seems applicable for almost all indications for liver transplantation in children.

▪ Figure 53.6 Percentage of patients with fibrosis in their liver allograft at various intervals after deceased donor liver transplantation (DDLT) or living donor liver transplantation (LDLT). Solid bars represent portal fibrosis. Hatched bars represent bridging fibrosis. None of the patients in either group developed cirrhosis during the follow-up period. No significant difference in the percentage of patients who developed fibrosis existed between the two groups. (From Shiffman ML, Stravitz RT, Contos MJ, et al. Histologic recurrence of chronic hepatitis C virus in patients after living donor and deceased donor liver transplantation. Liver Transpl 2004;10:1248–1255.)

Paramount to selection of recipient candidates for living donor liver transplantation is a thorough assessment of the donor's risks for donation, estimation of the potential of success for the recipient, and fully informed consent from both donor and recipient.

Timing of Liver Transplantation in the Context of Organ Allocation In an ideal world, all patients would receive the most effective treatment at the time when they are most likely to gain the most benefit and suffer the least harm from that intervention. However, because liver transplantation is severely limited by the availability of the therapeutic substrate, there must be some method for selection, from all those who could potentially benefit, of the few individuals who

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will receive the treatment. Therefore, the timing of liver transplantation for individual patients will be determined in large part by this allocation/selection process regardless of the presence of a beneficial potential that a transplantation may pose for any of the waiting patients. Living donor transplantation introduces some flexibility for the timing of these cases, but because only approximately 5% of liver transplantation procedures in 2004 were from living donors (115), the timing of most liver transplantation procedures depends on the allocation system. Timing for these patients is not so much determined by what is most appropriate for that individual to maximize success and minimize complications and/or failures but by what is the most equitable for all users of the organ donor pool. Equitability is difficult to define, but prioritization of the measures of equitable outcomes is possible. Because deceased individuals cannot have a quality of life or growth or development, or otherwise improvement in their burden of disease, it is difficult to accept any form of liver allocation in which these nonmortality endpoints supersede the risk of death. Consequently, prioritizing an individual with a very poor quality of life or delayed growth and development before someone with a higher mortality risk is difficult to justify. However, risk of disease progression, as is conceptualized in liver allocation for patients with HCC in the United States, can also serve as an equitable prioritization tool. Therefore, timing of deceased donor liver transplantation will depend mostly on which individual from among all the waiting candidates has the highest mortality risk (or risk of disease progression) if he or she continues to wait although there may be many other individuals on the list for whom transplantation at that point of time would also be beneficial.

Annotated References Freeman RB. MELD and Quality of Life. Liver Transpl 2005;11:134–136. A discussion on the balance between health-related quality of life and mortality risk in selecting candidates for liver transplantation. Krowka MJ, Mandel MS, Ramsay MA, et al. Hepatopulmonary syndrome and portopulmonary hypertension: a report from a multicenter liver transplant database. Liver Transpl 2004;10:174–182. This paper reports the largest experience of patients with hepatopulmonary and portopulmonary syndromes. Lucey MR, Brown KA, Everson GT, et al. Minimal criteria for placement of adults on the liver transplant waiting list: a report of a national conference organized by the American Society of Transplant Physicians and the American Association for the Study of Liver Diseases. Liver Transpl Surg 1997;3:628– 637. This is the first consensus document on minimal listing criteria for liver transplant candidates. These minimal listing criteria can be defined as minimal “selection” criteria because listing and selection are more or less synonymous. Mazzaferro V, Regalio E, Doci R, et al. Liver transplantation for the treatment of small hepatocellular carcinomas in patients with cirrhosis. N Engl J Med 1996;334:693–699.

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This study documented the excellent survival rates attainable for patients with early stage HCC with liver transplantation. In this paper, tumor stage criteria for which these excellent survival rates could be obtained were proposed, and these have served as the basis for most liver transplantation centers’ acceptance criteria for patients with HCC. McDairmid SV, Anand R, Linblad A. Development of a pediatric end-stage liver disease score to predict poor outcome awaiting liver transplantation. Transplantation 2002;74:173–181. Excellent description of the development of a mortality risk model for children with chronic liver disease. Merion RM, Schaubel DE, Dykstra DM, et al. The survival benefit of liver transplantation. Am J Transplant 2005;5:307–313. A carefully executed study comparing the risk of remaining on the waiting list with the risk of liver transplantation for patients with various P.1463 MELD scores. This study clearly shows that there is no survival benefit in offering liver transplantation to patients with low MELD scores as measured by 1-year survival rates. Pauwels A, Mostefa-Kara N, Florent C, et al. Emergency liver transplantation for acute liver failure; evaluation of London and Clichy criteria. J Hepatol 1993;17: 124–127. This study compares the King's College and Clichy criteria for their ability to predict outcome for patients with acute liver failure. Wiesner RH, Edwards EB, Freeman RB, et al. Model for end stage liver disease (MELD) and allocation of donor livers. Gastroenterology 2003;124:91–96. A description of how the MELD score, a model to predict mortality risk for patients with chronic liver disease, can be used to “select” which patients should receive the first organ offer for transplantation.

References 1. Epstein SK, Freeman RB, Khayat A, et al. Aerobic capacity is associated with 100-day outcome after hepatic transplantation. Liver Transpl 2004;10:418–424.

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62. Krowka MJ, Plevak DJ, Findlay JY, et al. Pulmonary hemodynamics and peri-operative cardiopulmonary-related mortality in patients undergoing liver transplantation. Liver Transpl 2000;6:443–450.

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64. Starkel P, Vera A, Gunson B, et al. Outcome of liver transplantation for patients with portopulmonary hypertension. Liver Transpl 2002;8:382–388.

65. Kuo P, Johnson L, Plotkin J, et al. Continuous intravenous infusion of epoprostenol for the treatment of portopulmonary hypertension.

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67. Koneru B, Ahmed S, Weisse A, et al. Resolution of pulmonary hypertension of cirrhosis after liver transplantation. Transplantation 1994;58:1133–1135.

68. Anderson R. Familial amyloidosis with polyneuropathy: a clinical study based on patients living in northern Sweden. Acta Med Scand 1976;198(Suppl 590):S1–S76.

69. Pomfret EA, Lewis WD, Jenkins RL, et al. Effect of orthotopic liver transplantation on progression of familial amyloidotic polyneuropathy. Transplantation 1998;65:918–925.

70. Suhr OB, Herlenius G, Friman S, et al. Liver transplantation for hereditary transthyretin amyloidosis. Liver Transpl 2000;6:263–276.

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74. Leonard JV, McKiernan PJ. The role of liver transplantation in urea cycle disorders. Mol Genet Metab 2004;81(Suppl 1):S74–S78.

75. Whitington PF, Alonso EM, Boyle JT, et al. Liver transplantation for the treatment of urea cycle disorders. J Inherit Metab Dis 1998;21(Suppl 1):112– 118.

76. Ensenauer R, Tuchman M, El-Youssef M, et al. Management and outcome of neonatal-onset ornithine transcarbamylase deficiency following liver transplantation at 60 days of life. Mol Genet Metab 2005;84(4):363–366.

77. Nyhan WL, Khanna A, Barshop BA, et al. Pyruvate carboxylase deficiency—insights from liver transplantation. Mol Genet Metab 2002;77(1–

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2):143–149. P.1465 78. Bodner-Leidecker A, Wendel U, Saudubray JM, et al. Branched-chain L amino acid metabolism in classical maple syrup urine disease after orthotopic liver transplantation. J Inherit Metab Disord 2000;23:805.

79. Mohan N, Mekiernan P, Preece MA, et al. Indications and outcome of liver transplantation in tyrosinemia type 1. Eur J Pediatr 1999;158:159.

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81. Superina RA, Zangari A, Acal L, et al. Growth in children following liver transplantation. Pediatr Transplant 1998;2(1):70.

82. Tornqvist J, Van Broeck N, Finkenauer C, et al. Long-term psychosocial adjustment following pediatric liver transplantation. Pediatr Transplant 1999;3(2):115.

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85. Schulz KH, Wein C, Boeck A, et al. Cognitive performance of children who have undergone liver transplantation. Transplantation 2003;75:1236–1240.

86. Avitzur Y, De Luca E, Cantos M, et al. Health status ten years after pediatric liver transplantation—looking beyond the graft. Transplantation 2004;78:566–573.

87. Burdelski M, Nolkemper D, Ganschow R, et al. Liver transplantation in children: long-term outcome and quality of life. Eur J Pediatr 1999;158(Suppl 2):S34.

88. Dhawan A, Taylor RM, Cheeseman P, et al. Wilson's disease in children: 37-year experience and revised King's score for liver transplantation. Liver Transpl 2005;11:441–448.

89. O’Grady JG, Alexander GJ, Hayllar KM, et al. Early indicators of prognosis in fulminant hepatic failure. Gastroenterology 1989;97:439–445.

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90. Bernuau J, Samuel D, Durand F. Criteria for emergency liver transplantation in patients with acute viral hepatitis and factor V below 50% of normal. Hepatology 1991;14:49A.

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Editors: Title:



Copyright ©2007 Lippincott Williams & Wilkins > Table of Contents > Volume 2 > Section XII - Elements of Liver Transplantation > Chapter 54 - Immunosuppression: The Global Picture

Chapter 54 Immunosuppression: The Global Picture K. V. Narayanan Menon Russell H. Wiesner

Key Concepts z

Advances in immunosuppression in recent years have led to impressive patient and graft survival rates and reduced rejection rates in liver transplantation.

z

Initially immunosuppressive regimens included combination therapy with corticosteroids and azathioprine. This was followed by the introduction of antilymphocyte globulin, cyclosporine, FK506, mycophenolate mofetil, and rapamycin. A number of cytokine antibodies antagonistic to specific targets in the antigen recognition pathway, such as OKT3 and antithymocyte globulin, are also in use to help prevent rejection.

z

Therapy with calcineurin inhibitors (cyclosporine or FK506) in combination with corticosteroids, azathioprine or mycophenolate mofetil is a popular regimen. Although used as induction therapy and in the treatment of rejection, use of corticosteroids has been declining especially in long-term transplant recipients. A major side effect of immunosuppression is the development of calcineurin inhibitor nephrotoxicity.

z

Regular biochemical monitoring with drug levels and renal function is essential to ensure adequate immunosuppression and to prevent the development of immunosuppression-related side effects.

z

The development of immunosuppressive agents that are less nephrotoxic may help decrease the incidence of renal failure in the long-term.

Outcomes after liver transplantation have shown consistent improvement in the recent years. Three and 5-year patient survival rates following deceased donor liver transplantation are 78% and 72% respectively, with graft survival slightly lower at 72% at 3 years and 64% at 5 years post-transplantation (1). These impressive patient and graft survival rates have been due to advances in surgical techniques and immunosuppression over the years. The use of combination therapy with corticosteroids and azathioprine by Thomas Starzl in the early 1960s brought about initial success in renal transplantation (2). This initial regimen was followed by the use of antilymphocyte globulin (ALG) in the late 1960s and early 1970s. The discovery and subsequent introduction of cyclosporine in 1979 represented a major breakthrough in the field of immunosuppression and resulted in continued improvements in patient and graft survival in organ transplantation. Immunosuppression in organ transplantation has been further refined by the

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development and introduction of other agents such as FK 506 (tacrolimus), mycophenolate mofetil (MMF), rapamycin and a number of cytokine antibodies targeted against specific mediators in the allograft rejection pathway. The goal of clinical immunosuppression is to provide graft acceptance with minimal side effects. However, the use of most immunosuppressive agents is associated with significant adverse effects requiring close monitoring and modification of therapy. An alternative strategy to immunosuppression in organ transplantation is to P.1468 try and induce tolerance in the recipient. Tolerance is the state of host nonresponsiveness to the transplanted organ and is induced by previous exposure to the antigen. The induction of tolerance may allow reduction in the level of immunosuppression and in some instances, may lead to its complete withdrawal. Although a few centers are involved in tolerance inducing protocols, currently there are no completely successful protocols and the induction of tolerance remains the holy grail of transplantation. In the absence of true tolerogenic protocols, immunosuppression remains the key to successful organ transplantation.

Overview of the Immune Response and General Features of Immunosuppression T cells respond to peptide antigens bound to the groove of class I (CD8 T cells) or class II (CD4 T cells) major histocompatibility complex (MHC). Recognition of foreign alloantigens is carried out by the recipient T lymphocytes through one of two pathways (Fig. 54.1). Donor hepatic antigen-presenting cells (APCs) express MHC molecules recognized by recipient T lymphocytes in the direct pathway. In the indirect pathway, recipient T lymphocytes react to donor alloantigen derived peptides expressed on recipient APCs. In liver transplantation, there is evidence that both these mechanisms exist (3). It is possible that the direct pathway is active during the early post-transplantation period, playing a major role in the development of acute cellular rejection. Here the APCs expressing donor antigens from the graft migrate and enter into secondary lymphoid tissue where they encounter allospecific T cells (4). These T cells, primed through the direct pathway, interact with the allograft and promote rejection. In the later stages, the indirect pathway may be important in sustaining a persistent response to the graft. This probably occurs as a result of donor antigen P.1469 derived from damaged donor liver being picked up and presented by self APCs resulting in the activation of T cells. Phagocytosis of apoptotic donor cells may be an important source of antigen for indirect presentation. However, the relative interplay and importance of the direct and indirect pathways in allograft rejection remain to be further clarified (5). Once the T-cell receptor, which is the antigen recognition unit, interacts with the MHC/peptide complexes on the surface of the presenting cell, accessory molecules including CD3 and CD4 or CD8 are brought into play. The T-cell receptor/CD3 complex interacting with the MHC molecule of the APC results in the activation of the T cell (signal 1). However, it is not known that more than one signal is needed to activate the immune system (6). Activation of the immune system by an antigen requires not only the antigen (signal 1), but also a signal from a secondary molecule (signal 2). It is also postulated that if a lymphocyte only received the signal from the antigen, it would not only fail to respond, but would also fall into a state of inactivity termed anergy (5). This forms the basis of the two-signal model by which full T-cell

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activation is dependent upon a complex array of regulatory molecules called costimulatory molecules (Fig. 54.2). Signal 2, a calcium-independent process, results from binding of the costimulatory molecules found on T cells with their ligands found on the APCs. Expression of costimulatory ligands on the APC is induced by factors released during tissue injury (so-called danger signals). Signal 1 and signal 2 activate an array of intracellular events mediated by calcineurin, protein C kinase, zeta associated protein-70, activation of nuclear factor of the activated T cells (NFAT), NF-κB, and activated protein (AP)-1 respectively. These factors migrate to the nucleus and bind to various gene promoters associated with T-cell activation and proliferation initiating the G0 to G1 transition in the cell cycle. P.1470 Further progression of T-cell activation results from autocrine and paracrine cytokine mediated signaling via specific cytokine receptors that include the interleukin (IL)-2 receptor family (often referred to as signal 3). An important cytokine is IL-2 that binds to the IL-2 receptor gamma chain and activates Janus kinase (JAK) 1 and 3. This triggers additional intracellular signaling pathways including signal transducers and activators of transcription (STAT) 5, Ras-RafMAP kinase, and mammalian target of rapamycin (mTOR)/P13-k/p7056 kinase (7). The cytokines generated by activated T cells facilitate the generation of effector cells such as antibody secreting B cells, cytotoxic T cells, and activated macrophages. Subsequently, these cells upregulate cell adhesion molecules such as CD2, LFA1, and VLA4 resulting in alteration of the migration pattern of cells. T cells also mediate cell damage by secretion of numerous factors such as tumor necrosis factor (TNF)-α, TNF-β (lymphotoxin), and fas ligand expression as well as cytotoxins such as perforin and granzymes F.

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▪ Figure 54.1 Allorecognition pathways and graft rejection. A: Pathways of allorecognition. In the “direct” pathway, T cells recognize intact major histocompatibility molecules on donor antigen-presenting cells (left). In the “indirect” pathway, T cells recognize processed alloantigen in the form of peptides presented by recipient antigen-presenting cells (right). B: Interactions among endothelial cells, T cells and recipient antigen-presenting cells in allograft rejections. The recipient monocytes are recruited by endothelial cells to the graft tissue. They are also transformed to become highly efficient antigen-presenting dendritic cells that may need to recirculate to peripheral lymphoid organs for maturation. The dendritic cells and intragraft macrophages present donor peptides via the indirect pathway to recruited CD4 + T cells. CD8 + T cells, on the other hand, are activated by donor endothelial cells or traverse the endothelium and kill parenchymal graft cells. APC, antigen-presenting cell. (Reprinted with permission from Briscoe DM, Sayegh MH. A rendezvous before rejection: where do T cells meet transplant antigens? Nat Med 2002;8:220–222.)

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▪ Figure 54.2 The two-signal hypothesis. In signal 1, the major Histocompatibility complex on the antigen-presenting cell interacts with the T cell receptor. B7-1 (CD80) and B7-2 (CD86) on the antigen-presenting cell interact with the respective ligands, CD28 and CTLA4 (CD152). CD28 and CTLA4 share common motifs (MYPPY) that are essential for binding B7-1 and B7-2. Regulatory molecules, such as programmed death 1 (PD-1) and inducible costimulator, which have different motifs, enter the regulatory cycle by affecting experienced T cells. CD28 and CTLA4 have similar structures, but opposite functions. CD28 activates T cells, whereas, CTLA4 inhibits them. PD-L1, programmed death ligand 1; PD-L2, programmed death ligand 2; MHC, major histocompatibility complex; ICOS, inducible costimulator; IgV, immunoglobulin V; IgC, immunoglobulin C. (Reprinted with permission from Ingelfinger JR, Schwartz RS. Immunosuppression—the promise of specificity. N Engl J Med 2005;353:836–839.)

Overview of Immunosuppressive Agents

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Broadly, immunosuppressive agents consist of two types: Pharmacologic and biologic. Biologic agents comprise the antilymphocyte antibodies (both the monoclonal and the polyclonal) and anticytokine receptor antibodies. Pharmacologic agents consist of corticosteroids, cytokines, suppressive agents, and cell cycle inhibitors (Table 54.1). Immunosuppressive agents act by inhibiting the pathways of foreign antigen recognition, T-cell activation, and costimulation. There are also other agents that inhibit a variety of other processes in the immune recognition pathway or lymphocyte trafficking. In addition, there are a few agents wherein the exact mechanism of action is still unknown.

Table 54.1. List of Clinically Available Immunosuppressive Agents and Target Pathways

Immunosuppressive agent

Target pathway(s)

PHARMACOLOGIC

Corticosteroids

Selective lysis of immature cortical thymocytes Blockade of cytokine gene transcription in APC

Cyclosporine (Sandimmune, Neoral, Gengraf)

Signal 1 transduction through TCR

Tacrolimus (Prograf)

Signal 1 transduction through TCR

Rapamycin/Sirolimus and Everolimus/SDZ RAD (Rapamune

Signal 3 transduction through IL-2 receptor

and Certican)

Azathioprine (Imuran)

Inhibition of purine metabolism and DNA synthesis

Mycophenolic acid (CellCept,

Inhibition of purine metabolism

Myfortic)

and DNA synthesis

BIOLOGIC

Anti-CD3 pan-T cell (Orthoclone OKT3)

Causes depletion and receptor modulation in T cells Interferes with signal 1

Antithymocyte globulin (ATGAM,

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Causes depletion and receptor

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Thymoglobulin)

modulation in T cells Interferes with signals 1, 2, and 3 Inhibits lymphocyte trafficking

Anti-II–2 α-chain receptor

Inhibits T-cell proliferation to

(Zenapax, Simulect)

IL-2 (signal 3)

Anti-CD52 (Campath 1-H)

Causes depletion of thymocytes, T cells, B cells (not plasma cells), monocytes

APC, antigen-presenting cells; TCR, T cell receptor; IL, interleukin; DNA, deoxyribonucleic acid.

Corticosteroids were one of the earliest immunosuppressants used in the field of organ transplantation. Corticosteroids, in combination with the antimetabolite azathioprine, the earliest widely used immunosuppressive drug in transplantation, made renal transplantation a realistic option in the 1960s. Starzl et al. (2) and Murray et al. (8) showed independently that combining corticosteroids with azathioprine enabled prolonged survival of human renal allografts. Corticosteroids continue to play a major role in immunosuppression in liver transplantation. A recent report by the Scientific Registry of Transplant Recipients (SRTR) from an analysis from the United Network of Organ Sharing (UNOS) database revealed that corticosteroids were used in more than 90% of liver transplant recipients at the time of discharge (1). The use of azathioprine, however, has declined and only 4% of patients discharged from the hospital following liver transplantation were on this drug (1). Following the success of combination therapy with azathioprine and prednisone, the field of immunosuppression advanced in the late 1960s and early 1970s with the introduction of ALG and monoclonal anti–T-cell antibodies such as OKT3. However, immunosuppression finally came of age in the late 1970s with the description by Borel JF et al. of the striking effects of cyclosporine on the immune system, and the demonstration by Calne et al. P.1471 of the impressive advantage of using cyclosporine A in patients undergoing renal transplantation (9,10). Subsequently in 1989, FK506 (tacrolimus) was used in transplantation for multiple indications including treatment of persistent rejection with continued decrease in the incidence of rejection (Fig. 54.3) (11). Currently the field of immunosuppression is expanding with a number of agents with differing modes of action being studied for use in liver transplantation. Rapamycin which inhibits signal transduction, a different mechanism of action from tacrolimus which basically inhibits lymphokine synthesis, is currently being used in select patients in liver transplantation. MMF, a drug that blocks purine synthesis and salvage pathways is also being increasingly used in liver transplantation with approximately 50% of patients being on it at the time of discharge (1). Antibodies directed against T lymphocytes such as antithymocyte globulin or against specific cytokines such as the IL-2 receptor antibodies are also being increasingly used. A variety of investigational agents such as FK778,

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WH1 P154 and FTY720 are also being tested (Table 54.2).

▪ Figure 54.3 Trends in evidence of rejection at one year in liver transplant recipients, 1992–2001. (Reprinted with permission from Kaufman DB, Shapiro R, Lucy MR, et al. Immunosuppression: Practice and trends. Am J Transplant 2004;4(Suppl 9):38–53.)

Table 54.2. Investigational Immunosuppressive Agents in Clinical Testing and Target Pathways

Immunosuppressive agent

Target pathways

FK778

Interferes with pyrimidine metabolism and DNA synthesis

WHI P 154

Signal 3 transduction through JAK3/STAT5

LEA29Y

Signal 2—also known as CTLA4-Ig and inhibits B7/CD28 interaction

FTY720

Inhibits naïve T cell homing to the high venule endothelial cell on secondary lymphoid tissue

DNA, deoxyribonucleic acid; JAK, janus kinase; STAT, signal transducers and activators of transcription.

Corticosteroids

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Corticosteroids were one of the earliest agents used for immunosuppression, first developed in the late 1940s and introduced into immunosuppressive regimens in the late 1950s (12). They have been applied in a variety of ways in liver transplantation. These include: (i) As induction immunosuppression by way of bolus corticosteroid therapy at the time of organ implantation, (ii) as maintenance therapy to prevent rejection, and (iii) in the treatment of established acute cellular rejection. Although their chronic, long-term use is somewhat disputed in recent years, they continue to be widely used both in induction therapy and during short-term maintenance therapy in liver transplantation. Corticosteroids have multiple effects and their exact mechanism of action is unknown. The most common agents used in liver transplantation include prednisone, prednisolone, and methylprednisolone. These steroid agents possess a predominantly anti-inflammatory immunosuppressive potency with relatively low mineralocorticoid potency. Prednisone is rapidly absorbed from the gastrointestinal tract; however, it needs to be metabolized to prednisolone for biologic activity. Following absorption, corticosteroids are primarily metabolized into inactive compounds by the liver and excreted in the urine. They exert their effects through their actions on a wide variety of white cells (including lymphocytes, granulocytes, macrophages, and monocytes) and endothelial cells. Glucocorticoids circulate either in the free form or in association with cortisolbinding globulin in the blood. The free form of the steroid readily diffuses through the plasma membrane of lymphocytes and binds with high affinity to intracellular glucocorticoid receptors. This ligand receptor complex, following activation, modulates transcription both positively and negatively, in the nucleus of specific genes P.1472 and coding factors critical in the generation and maintenance of the immune and the inflammatory responses. In addition to modulating transcription, glucocorticoids can also influence later cellular events including RNA translation, protein synthesis, and secretion (13). Leukocytes, by their mechanism of localization and activation, generate numerous products that play a key role in cellular rejection, and corticosteroids therefore, modulate this function. On lymphocytes the major mechanism of action of corticosteroids seems to be a negative regulation of cytokine gene expression. Regulation of cytokine gene production occurs through the inhibitory action of glucocorticoid on gene transcription through inhibition of AP-1 and nuclear factor NF-κB. Glucocorticoids also affect other cells such as macrophages, neutrophils, eosinophils, basophils, mast cells, and endothelial cells. Glucocorticoids antagonize macrophage differentiation and inhibit many of their functions that promote inflammation. Glucocorticoids inhibit neutrophil adhesion to endothelial cells, thereby decreasing their extravasation to the site of inflammation. This process may partly explain the neutrophilia that is seen with glucocorticoid therapy. However, neutrophil functions are only minimally influenced by glucocorticoids. In addition to their action on neutrophils and macrophages, glucocorticoids also decrease circulating eosinophil and basophil counts, inhibit IgE-dependent release of histamine and leukotriene from basophils and inhibit degranulation of mast cells. Additionally, glucocorticoids downregulate endothelial cell function including expression of class II MHC antigen, expression of adhesion molecule (ELAM-1) and the intracellular cell adhesion molecule (ICAM)-1), formation of IL-1 and arachidonic acid metabolites, thereby inhibiting the expression of cyclooxygenase type II. Corticosteroids are administered at various stages of liver transplantion. High-

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dose methylprednisolone is usually given intravenously around the time the liver is implanted, and continued for several days postoperatively. Induction doses range from 300 to 1,000 mg intravenously. Initially thought to be essential, trials have now demonstrated that corticosteroid-free regimens do not necessarily lead to increased rejection (14,15,16,17). These trials have however, used other induction agents such as antithymocyte globulin or IL-2 receptor antibodies. For maintenance therapy, steroids are rapidly tapered from the time of surgery to a daily maintenance dose of 5 to 10 mg per day. Subsequently, many centers now taper and stop prednisone after 3 to 6 months. Prednisone cessation does not seem to adversely affect the graft in most instances and may be beneficial in ameliorating some of the side effects of long-term prednisone use such as osteoporosis, diabetes, weight gain, hypertension, cataracts, hyperuricemia, and cosmetic problems. However, in patients who have undergone transplantation for autoimmune liver disease and in patients with conditions such as ulcerative colitis continuing prednisone therapy, albeit at a low-dose, may be prudent. Corticosteroids have also been used in the treatment of acute cellular rejection. In this context, intravenous methylprednisolone is given at a dose of 1,000 mg on alternate days for a total of 3 doses. The high-dose intravenous regimen for the treatment of rejection is usually stopped after this intensive protocol (18).

Table 54.3. Side Effects of Corticosteroids

Impaired wound healing Hypertension Weight gain Hyperglycemia Hyperlipidemia Osteoporosis Fluid retention Hirsutism Acne Myopathy Cataracts Infection

Corticosteroid therapy is not without its side effects. Short-term corticosteroid use such as IV boluses to treat acute cellular rejection may cause transient hyperglycemia. Infections can also be unmasked or exacerbated by short-term high-dose corticosteroids. In patients with hepatitis C, the use of bolus high-dose intravenous corticosteroid therapy to treat acute cellular rejection has also been associated with a more severe and earlier recurrence of hepatitis C (19). Longterm corticosteroid therapy is associated with a number of side effects some of which may be reversed by steroid withdrawal (Table 54.3). Cosmetic side effects such as acne and hirsutism may adversely affect compliance especially in the younger population undergoing transplantation.

Azathioprine Azathioprine was one of the earliest agents to be used in combination with corticosteroids in the long-term management of the transplant recipient, and has brought about a major improvement in graft survival. Azathioprine is absorbed

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readily from the gastrointestinal tract, and peak plasma concentrations are achieved 1 to 3 hours after oral administration (20,21). Azathioprine is rapidly cleared from the circulation but approximately 30% is bound to serum proteins. Azathioprine is a derivative of mercaptopurine, which is rapidly metabolized to 6mercaptopurine and subsequently to other active and inactive metabolites. The metabolites P.1473 are excreted through the urine with little intact drug excreted. The half-life of azathioprine is approximately 3 hours with normal kidney function and up to 50 hours in patients with anuria. The active metabolite acts as a purine analog, which is incorporated into cellular DNA and inhibits purine nucleotide synthesis and metabolism. The resultant alteration in RNA synthesis and function prevents mitosis and proliferation. Azathioprine acts early during the proliferative phase of cell cycle thereby inhibiting primary cell-mediated and humoral responses (22). Azathioprine was first used in combination with corticosteroids for renal transplantation, and was found to be highly efficacious. It is currently used in combination with a calcineurin inhibitor and corticosteroids. Daily doses between 1 and 2 mg/kg are generally used in combination therapy. More lately, azathioprine has been replaced by MMF in a large number of transplant recipients as reported by the SRTR from their analysis of the UNOS database. Use of azathioprine at the time of discharge from the hospital was noted in only 4% of patients compared with 48% of patients on MMF. Although used for a number of years, azathioprine has well-documented side effects. These include myelosuppression, reversible hepatotoxicity, alopecia, and gastrointestinal side effects such as nausea and dyspepsia, and acute pancreatitis. Other short-term side effects include the development of fever, skin rash, arthralgias, myalgias, and an acute hypersensitivity reaction. During longterm therapy an increased incidence of malignancies of the skin such as squamous cell carcinoma, and non-Hodgkin's lymphoma have been reported. Xanthine oxidase, a major enzyme in the catabolism of azathioprine metabolites is blocked by allopurinol and hence, when used concurrently with allopurinol the dose of azathioprine must be decreased to 25% to 33% of the original dose. Other drugs that interact with azathioprine and worsen its bone marrow suppression include methotrexate and angiotensin converting enzyme inhibitors.

Cyclosporine Cyclosporine is a highly aliphatic cyclic undecapeptide. It was originally isolated from the soil fungus cylindrocarpon lucidum (9). Since its discovery, cyclosporine has remained the cornerstone of immunosuppression, not only for liver transplantation, but also for kidney, heart, and other organ transplantations. Cyclosporine came into widespread clinical use in the early 1980s in renal transplantation and was responsible for significantly improving early graft survival with some centers reporting almost doubling of their graft survival rate (10,23). In liver transplantation, Starzl et al. reported the first use of cyclosporine and prednisone in 1981 with 83% of their patients alive after 8 to 14½ months (23). Cyclosporine enters cells and lymphocytes through diffusion and at high concentrations by active transport through the low-density lipoprotein (LDL) cholesterol receptor. In the cell, cyclosporine binds to a number of carrier proteins including cyclophilin, which are important for protein folding. The cyclosporine/cyclophilin complex binds to calcium activated calcineurin, a serene

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threonine phosphatase important in the lymphocyte activation cascade, preventing the dephosphorylation of the transcription factor, NFAT. This prevents NFAT from engaging to specific DNA- binding sites in the promotor region of several T-cell growth factors and cytokines such as IL-2, interferon-γ, TNF-α, and costimulatory molecules such as CD40. This lack of engagement downregulates the expression of these various cytokines essential for the rejection process (24,25). Therefore, cyclosporine enables the activated cells to potentially return to their quiescent state inhibiting early antigen recognition, reducing clonal expansion, and inhibiting the synthesis of multiple cytokines necessary for rejection. Cyclosporine is not cytotoxic and does not inhibit the myeloid or the erythroid cell lines. An earlier formulation of cyclosporine (Sandimmune) was notable for variable absorption and bioavailability. However, with the recent introduction of a microemulsion nonaqueous form (Neoral), absorption and bioavailability have become more predictable (26). Cyclosporine is absorbed primarily in the proximal jejunum, and achieves peak blood levels in 2 to 4 hours (26). It is widely distributed with highest concentrations found in adipose, kidney, adrenal, pancreatic, and liver tissues. Cyclosporine is metabolized primarily through the liver, occurring through the P450 system and excreted predominantly through the bile (22). Therefore, with liver failure, the propensity to develop toxic cyclosporine concentrations should be recognized. Cyclosporine has an average half-life of approximately 27 hours (range 10 to 40 hours). Various drugs that stimulate or inhibit the hepatic P450 enzyme system may increase or decrease dose levels and can result in underimmunosuppression or toxicity. These agents include the calcium channel blockers, antifungal agents, macrolide antibiotics, prokinetic agents such as cisapride and metoclopramide, and a variety of miscellaneous agents such as amiodarone, cimetidine, omeprazole, and protease inhibitors. Dosing of cyclosporine is generally regulated by examining a 12-hour trough level, as this is convenient to patients. However, it has been shown that trough concentrations do not accurately reflect the area under the curve for cyclosporine exposure in individual patients. More recently, the peak cyclosporine level at 2 hours after P.1474 oral administration is thought to be a better measure of the area under the curve, and may be more useful in controlling toxicity and enhancing efficacy. Target trough and peak levels vary with respect to time after liver transplantation. Within the immediate post-transplant period, 12-hour trough levels between 250 and 300 ng/mL are desirable. With time, however, 12-hour trough levels between 100 and 125 ng/mL may be sufficient to prevent rejection and minimize toxicities. Cyclosporine is commonly used in conjunction with prednisone and either azathioprine or MMF soon after transplantation. With time, the other agents may be withdrawn leaving cyclosporine as the sole immunosuppressant. The main side effects of cyclosporine include nephrotoxicity and hypertension (27,28). With long-term follow-up of liver transplant patients, it is becoming apparent that 15% to 20% of the patients on calcineurin inhibitors will end up with chronic renal insufficiency requiring dialysis and/or renal transplantation (29,30). The nephrotoxicity of cyclosporine is thought to result from its vasoconstrictor effects on renal blood vessels. Although early toxicity resulting in renal dysfunction may be reversible, the late stages of cyclosporine nephrotoxicity resulting in advanced tubular interstitial fibrosis and scarring may be irreversible. Other significant side effects from cyclosporine include neurologic

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sequelae, which occur in 10% to 20% of the patients (20). These include paresthesias, tremors, hallucinations, confusions, and migraine-like headaches. Other rare side effects may include seizures, especially in patients receiving intravenous cyclosporine. Cyclosporine may also cause hirsutism and gingival hyperplasia that causes significant cosmetic problems in the younger patient undergoing transplant (28). Other less commonly reported side effects include nausea, vomiting, thrombocytopenia, allergic reactions, tinnitus, myalgias, and arthralgias.

Tacrolimus Tacrolimus (FK506) is a metabolite of a fungus streptomyces tsukubaensis and was isolated in 1986 (31). Its mechanism of action is identical to that of cyclosporine. When it enters the cell, it binds with an immunophilin referred to as FK-binding protein 12. This complex then inhibits calcineurin, preventing the dephosphorylation of the transcription factor NFAT and inhibiting the transcription of cytokines necessary for rejection (22). Tacrolimus is considered to be 10 to 100 times more powerful than cyclosporine. Its first successful use was reported by Starzl et al. in 1989 as rescue therapy for liver grafts failing conventional therapy (11). Subsequently, tacrolimus was evaluated for routine use in liver transplantation. A multicenter trial, that compared the efficacy and safety of tacrolimus with cyclosporine showed that tacrolimus was associated with significantly fewer episodes of corticosteroid resistant or refractory rejection, although graft survival and patient survival were not significantly different (32). Similar results were also seen in the European Multicenter Study; additional findings included a lower incidence of chronic rejection and infection. However, the use of tacrolimus in the US Multicenter Study was associated with a higher incidence of adverse events requiring withdrawal from the study, primarily nephrotoxicity and neurotoxicity. Tacrolimus has been proved to be safe and efficacious in long-term immunosuppression after liver transplantation with fairly low incidences of rejection and malignancies (33,34). Tacrolimus is absorbed in the duodenum and jejunum and, unlike cyclosporine, does not require the presence of bile (22). The recommended initial dose is 0.1 mg/kg/ per day every 12 hours. Initial levels after liver transplantation are maintained between 10 and 15 ng/mL. With time, 12-hour trough levels may be lowered to between 5 and 10 ng/mL to reduce side effects. Although initially used in combination with other immunosuppressive agents, most commonly corticosteroids and azathioprine or MMF, tacrolimus monotherapy in the later stages of liver transplantation is more widely practiced. The side effects of tacrolimus are similar to those of cyclosporine (35). The most significant effects include nephrotoxicity and neurotoxicity. The neurotoxic side effects of tacrolimus include headaches, insomnia, tremors, dysarthria, seizures, and coma (36). It may be necessary to switch over from tacrolimus to cyclosporine therapy to obviate some of these side effects. The incidence of hypertension may be lower with tacrolimus. Tacrolimus also seems to be a more diabetogenic medication when compared with cyclosporine with up to 10% of the patients developing de novo diabetes mellitus (37). The other side effects include hyperlipidemia, nausea, diarrhea, abdominal pain, and pruritus.

Mycophenolate Mofetil MMF is a prodrug that is rapidly hydrolyzed to its active metabolite, mycophenolic acid. It is a selective and noncompetitive inhibitor of inosine monophosphate

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dehydrogenase, which is an important enzyme in the de novo pathway of guanine nucleotide synthesis (22,38). This results in the inhibition of DNA synthesis in T and B lymphocytes thereby inhibiting cell proliferation and function. Other cell types can use salvage pathways and are not affected; therefore, the effects of MMF are largely seen on the immune cells with few effects on the nonimmune system. Although long known to be an P.1475 immunosuppressive, it is only recently that its use has increased in liver transplantation. MMF is metabolized to mycophenolic acid glucuronide which is excreted in bile and has an enterohepatic circulation. It is excreted in the urine in humans and to a lesser extent in the bile. There may be larger variations in pharmacokinetics in liver transplant recipients related to fluctuations in serum albumin, unlike that seen in renal transplant recipients (39). Clinically, MMF is used mainly as a replacement to azathioprine in liver transplantation. It has similar side effects as azathioprine, but it is less myelotoxic and has fewer hepatotoxic side effects. It is usually used in combination with a calcineurin inhibitor and steroids. The use of MMF in conjunction with corticosteroids and tacrolimus has been shown to be superior in preventing rejection and improving renal function than the combination of tacrolimus and corticosteroids alone. Patients discharged home on immunosuppression that included MMF appear to have better long-term patient and graft survival (40). It is possible that the use of MMF may enable a lower dose of a calcineurin inhibitor to be used or withdrawn, in an attempt to preserve renal function (41,42,43). Therefore, MMF may be particularly useful in patients who may be at a higher risk of rejection such as younger patients undergoing liver tranplantation for fulminant liver failure and patients with autoimmune liver disease. MMF as monotherapy after calcineurin inhibitor withdrawal has been associated with a high incidence of acute cellular rejection and steroid-resistant acute cellular rejection (44,45). Therefore, the use of MMF alone may not be sufficient to prevent rejection after liver transplantation. The usual dose is 1,000 mg given orally twice daily. Dose-reductions are made depending on toxicity. An enteric-coated preparation (Myfortic) is available that allows delayed release of the active drug in the small intestine rather than the stomach. This may help alleviate some of the gastrointestinal side effects of MMF. The significant side effects of MMF include gastrointestinal symptoms, mainly diarrhea, abdominal discomfort, anorexia, and bone marrow suppression including neutropenia. The incidence of side effects is high and dose dependent. Variations in pharmacokinetic from changes in serum albumin levels may increase the incidence of side effects if drug levels are high. Side effects may require dosereduction and withdrawal in 25% to 57% of patients (46). Occasionally patients with gastrointestinal side effects may respond to increasing the frequency of dosage to three or four times daily. Gastrointestinal side effects may be reduced by acid reduction with a proton pump inhibitor. Bone marrow suppression usually responds to dose-reduction, but in some instances may require drug discontinuation.

Rapamycin Rapamycin or sirolimus is a new macrolide antibiotic immunosuppressive agent. Rapamycin is structurally similar to tacrolimus. It is named after its isolation from the fungus, Streptomyces hygroscopicus, found in soil samples from Rapa

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Nui or Easter Island brought back in 1968. However, its immunosuppressive properties were not reported until 1988. Like the calcineurin inhibitors, cyclosporine and tacrolimus, rapamycin acts by binding to an immunophilin FKB12. However, this does not affect calcineurin activity, but instead, the complex binds to and inhibits a protein called the mTOR. Inhibition of mTOR results in selective inhibition of synthesis of new ribosomal proteins which are essential for progression of the cells from the G1 to the S phase (47). In addition, rapamycin has also been associated with diminished fibroblastic activity by its actions on the 70 kDa S6 kinase in the fibroblast (48). In liver transplantation, rapamycin is primarily used as an immunosuppressive agent for its renal sparing effect. In addition, it has some unique properties such as antiproliferative and antineoplastic effects, and hence may be useful in patients who undergo liver transplantation for hepatocellular carcinoma and cholangiocarcinoma. The usual regimen is to provide a loading dose, 5 mg PO, and continue with maintenance doses of 2 to 3 mg perday. It is usually used in the later post-transplant period and levels are maintained between 5 and 10 ng/mL. Rapamycin has a number of side effects, which currently restricts its usage in liver transplantation. (49,50,51,52). In early trials in liver transplantation, rapamycin was combined with FK506 in the immediate post-transplant period in an attempt to reduce the incidence of renal dysfunction. However, when used with FK506, rapamycin was associated with a higher incidence of adverse events which included thrombotic events such as hepatic artery thrombosis, infection, and death (53,54,55). Hence, most centers use rapamycin in the later posttransplant period, usually after a period of 3 to 6 months. The adverse effects of rapamycin include thrombocytopenia, leukopenia, anemia requiring blood transfusions, arthralgias, hyperlipidemia, pneumonitis, and diarrhea (56). There have also been reports of wound complications in the immediate post-transplant period (57). This effect is presumably a result of its antilymphoproliferative effects on fibroblasts, thereby delaying wound healing. Oral ulcers were seen with the liquid preparation; however, this does not seem to be a problem with the pill preparation. In addition to the those mentioned in the preceding text, there have been reports of an increased risk of nephrotoxicity when combining rapamycin with high doses of calcineurin inhibitors (58). P.1476 An analog of rapamycin, RAD (Everolimus) is currently undergoing clinical trials in liver transplantation. It differs from rapamycin only in its bioavailability.

Antibody Therapies Antibody therapies in liver transplantation may consist of either the polyclonal antibodies or monoclonal antibodies. Polyclonal antibodies include antithymocyte globulin and ALG. Polyclonal preparations may be obtained by immunizing either the horse or rabbit with different immunogens, whereas monoclonal antibodies are produced in response to a single antigen (59). The advent of hybridoma technology to fuse two cell lines, one capable of specific antibody production and the other capable of permanent cell growth, was a key breakthrough in monoclonal antibody production (60).

Polyclonal Antibodies Polyclonal antibodies include antithymocyte globulin and ALG, which are prepared

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by immunizing animals such as the horse or rabbit with immunogens from different sources. These immunogens may include lymphocytes, thymocytes, blast cells, or T cell lines. Antithymocyte globulin is produced by using human thymocytes as immunogens, whereas, ALG is produced by using human lymphocytes. Polyclonal agents have been in use since the early 1960s. The initial agents, termed antilymphocyte serum (ALS) consisted of unfractionated serum obtained from animals after immunization with human lymphocytes. Subsequently, this preparation was purified and the immunoglobulin was concentrated, as it was known that the immunosuppressive properties of the serum were contained in the immunoglobulin fraction. Various preparations of polyclonal antibodies are available throughout the world. In the United States, the commonly used preparations are antithymocyte globulins derived either from the horse (Atgam) or the rabbit (Thymoglobulin). The polyclonal antibodies exert their action through various mechanisms, which include complement mediated cell lysis, increased uptake of T cells by the reticuloendothelial system, and also by modulation of surface receptors of lymphocytes and blocking their function. The administration of polyclonal antibodies results in profound lymphopenia. Currently, they are not commonly used in liver transplantation. There have been reports of their successful use in corticosteroid-free protocols with comparable rates of rejection (14,15,16,17). In addition, they may have a role in the treatment of steroid-resistant acute cellular rejection. In addition to profound leukopenia, administration of antibody therapy is associated with the cytokine release phenomena characterized by fevers, chills, hypotension, which may require admission to the intensive care unit (60,61,62,63). Other less common side effects include nausea, diarrhea, arthralgias, thrombocytopenia, dyspnea, and seizures. Concerns about an increase in the infectious complications and increase in the incidence of posttransplant lymphoproliferative disorders are also present with the use of these therapies.

Monoclonal Antibodies Monoclonal antibodies are produced in relation to a specific antigen. These include the mouse monoclonal antibody muromonab (OKT3), which is specific to the CD3 receptor. Other antibodies include the IL-2 receptor antibodies that include daclizumab and basiliximab. In addition, other monoclonal antibodies such as Campath 18 (alemtuzumab) are also being investigated. OKT3 has been the most extensively used monoclonal antibody in liver transplantation. It was originally used in 1987 for prophylaxis against acute cellular rejection (64,65). OKT3 is directed against the CD3-antigen complex found on T cells. Binding of OKT3 to this complex results in deactivation of the CD3-antigen complex and subsequent internalization of the T cell receptor, thereby preventing subsequent antigen rejection (66). Administration of OKT3 results in rapid depletion and extravasation of most T cells from the blood stream and peripheral lymphoid organs such as lymph nodes and spleen. This depletion is secondary to both cell death and margination of the T lymphocytes onto vascular endothelial walls and redistribution to nonlymphoid organs such as the lungs. OKT3 is currently used for the treatment of steroid-resistant cellular rejection in liver transplantation (61,62). It is associated with a high incidence of adverse events related to the cytokine release phenomena, and premedication with steroids and/or antihistamines is generally advised (63) (Table 54.4). This syndrome usually occurs within an hour of drug administration during the first 2

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P.1477 to 3 doses of OKT3. Additionally, during OKT3 administration, prophylaxis against infections such as cytomegalovirus (CMV), pneumocystis and fungi are also advised. The use of OKT3 may also be associated with early and severe recurrences of hepatitis C after liver transplantation (67), and hence, must be used with caution in this cohort of patients. The total lymphocyte counts and CD3 counts are usually monitored during therapy and dose adjustments may be needed to ensure adequate suppression of the CD3 count.

Table 54.4. Side Effects of OKT3

Fever Hypotension Chills Headache Rash Nausea Vomiting Chest pain Diarrhea Pulmonary edema

Two IL-2 receptor antibodies, daclizumab and basiliximab, are currently being studied in liver transplantation. The exact mechanism of action is still incompletely understood, but likely results from their binding to the IL-2 receptor on the surface of activated, but not resting, T cells. They are fairly well tolerated and have a low incidence of side effects (58,68,69). They may be used for induction immunosuppression especially in patients with renal failure to provide a window of opportunity for the kidneys to recover before commencing calcineurin inhibitors. They have also been used for induction immunosuppression in corticosteroid-free protocols (70,71,72,73). Alemtuzamab or Campath is a humanized recombinant anti-CD52 monoclonal antibody. Campath produced profound depletion of circulating lymphocytes for about several months with slow lymphocyte recovery (74,75). Experimentally it has been used in the treatment of multiple sclerosis with thrombocytopenia and Graves' disease observed as side effects. Campath has been used in liver transplantation in tolerance inducing protocols (76). Severe recurrence of hepatitis C has been noted. Currently, the use of Campath in liver transplantation is considered experimental and its use is confined to research protocols.

Newer Immunosuppressive Agents The prevention of nephrotoxicity from calcineurin inhibitors remains a difficult challenge. The development of newer immunosuppressive agents that are less nephrotoxic may help prevent the development of renal dysfunction in the longterm. There are various agents currently being developed as immunosuppressive agents in liver transplantation. These include FK778, a synthetic analog of leflunomide which interferes with pyrimidine metabolism and DNA synthesis, FKY720 derived from lsiria sinclaivii, which alters cellular homing patterns of

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lymphocytes, JAK inhibitors that inhibit activation of immune cells, and agents such as CTLA4 IG and betacelept that cause costimulation blockade (77,78,79,80,81,82,83). These agents are all considered investigational and are currently undergoing clinical trials.

Goals of Immunosuppression The goals of immunosuppression are to control alloreactivity to eliminate acute rejection, but not adversely influence the development of recurrent hepatitis C, minimize side effects, preserve renal function, and reduce costs. In the absence of satisfactory markers of overall immunosuppression, tolerance and rejection/alloreactivity, and poor correlation between rejection and the degree of liver enzyme elevations or immunosuppression levels, immunosuppression in transplantation still remains an art. The key is to tailor immunosuppression to the individual patient. In patients with renal insufficiency at the time of liver transplantation, calcineurin inhibitors are withheld and an IL-2 receptor blocker may be used as an induction agent. Calcineurin inhibitors are introduced once renal function has recovered. In the event of non-recovery of renal function, the addition of rapamycin may be considered. Switching to rapamycin may also be considered in patients who develop renal dysfunction while on calcineurin inhibitors. An alternative to this regimen would be to consider adding MMF and lowering the dose of the calcineurin inhibitor. Patients with complications from long-term corticosteroid use may benefit from being weaned off from corticosteroids in a controlled fashion while carefully monitoring for rejection. Caution must be exercised before embarking on this protocol in patients who have undergone liver transplantation for autoimmune liver disease such as autoimmune hepatitis, primary sclerosing cholangitis or primary biliary cirrhosis, and in younger patients to prevent recurrent disease or rejection.

Conclusion Calcineurin inhibitors in conjunction with steroids and MMF continue to play a major role in immunosuppression following liver transplantation. Efforts are currently underway to develop newer immunosuppressants with less nephrotoxic effects, which will help reduce the incidence of long-term renal complications in these patients. In future, the development of these newer agents with less nephrotoxicity, and advances in inducing tolerance in the recipient will enable prolonged survival in patients undergoing liver transplantation.

Annotated References Fung J, Kelly D, Kadry Z, et al. Immunosuppression in liver transplantation. Liver Transpl 2005;11:267–280. A comprehensive review of current immunosuppression use in liver transplantation and future therapeutic regimens. Goodman LS, Gilman A, eds. The pharmacological basis of therapeutics, 11th ed. Chapter 52, New York: McGraw-Hill, 2006. P.1478 A review of the basic concepts of immunosuppression and the pharmacology of various immunosuppressive agents.

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Neuhaus P, Klupp J, Langehr JM. mTOR inhibitors. An overview. Liver Transpl 2001;7:473–484. A review of the salient properties of the mTOR inhibitors. Plosker GL, Foster RH. Tacrolimus: a further update of its pharmacology and therapeutic use in the management of organ transplantation. Drugs 2000;59:323–389. A comprehensive review of tacrolimus. Wiesner RH, Shorr JS, Steffen BJ, et al. Mycophenolate mofetil combination therapy improves long-term outcomes after liver transplantation in patients with and without hepatitis C. Liver Transpl 2005;11:750–759. In this registry study, liver transplant recipients discharged home on immunosuppression that included MMF appeared to have improved long-term patient and graft survival.

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Editors: Title:



Copyright ©2007 Lippincott Williams & Wilkins > Table of Contents > Volume 2 > Section XII - Elements of Liver Transplantation > Chapter 55 - The First 6 Months Following Liver Transplantation

Chapter 55 The First 6 Months Following Liver Transplantation Tram T. Tran Paul Martin

Key Concepts z

Clinical assessment immediately postoperatively in the liver transplant recipient focuses on hemodynamic stability and multiorgan function, including neurologic assessment and renal function, which reflect graft function. Early profound graft dysfunction suggests primary nonfunction or hepatic artery thrombosis (HAT), which necessitate prompt retransplantation

z

z

Care in the early weeks of post-transplantation care involves monitoring graft function for acute cellular rejection (ACR), prophylaxis against opportunistic infections such as cytomegalovirus (CMV), and management of immunosuppression and its side effects. Immunosuppression initially involves of calcineurin inhibitors (CNIs) (tacrolimus or cyclosporine) and corticosteroids, transitioning to maintenance regimens that reduce or eliminate corticosteroids. Adjunct agents such as mycophenolate mofetil or sirolimus are added in some cases, particularly if there is renal insufficiency

z

z

Significant side effects of immunosuppression including diabetes, hypertension, and hyperlipidemia need to be anticipated. Recommendations for routine health maintenance issues must be reinforced. ACR becomes less of a concern as patients progress further from the time of transplant but differentiation of rejection from recurrent disease can become a challenge during the initial 6 months. Chronic ductopenic rejection may evolve following ACR. Other important causes of late graft dysfunction include late recognition of HAT.

Intensive Care Unit Management Following liver transplantation (LT), the focus of medical care immediately shifts from managing the manifestations of decompensated liver disease to monitoring liver graft function, anticipating complications such as rejection, maintaining effective immunosuppression while minimizing its side effects, and caring for a patient recovering from complex major abdominal surgery. On return from the operating room to the intensive care unit (ICU), close clinical and hemodynamic monitoring is essential. Careful attention is paid to the patient's level of consciousness, urinary output, and hemodynamic status. Although less frequently used than previously in donor-recipient bile duct anastamosis, a T-tube allows easy assessment of bile output with pale scanty bile implying poor graft function. Assessment of the graft function in the initial 24 to 48 hours after transplantation may be somewhat difficult, as elevated serum aminotransferases and other biochemical evidence of graft injury due to a variety of factors including graft ischemia and reperfusion injury are the norm. Serum aminotransferases may be markedly elevated initially but should rapidly decline if graft function is satisfactory along with normalization of prothrombin time in the first several days post-LT. Simple clinical observations including alert mental P.1482

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status, adequate urine output, and hemodynamic stability are also reflective of good graft function. There are two major causes of profound graft dysfunction in the immediate postoperative period, which require prompt recognition: Primary graft nonfunction and hepatic artery thrombosis (HAT). Importantly, hyperacute rejection due to preformed antibodies is extremely rare post-LT. Primary graft nonfunction (PNF) occurs in 7% to 10% of allografts and is manifested by persistent coagulopathy, encephalopathy, poor bile production, and elevated serum aminotransferases in the immediate postoperative period. Risk factors for PNF include a reduced-size graft, donor graft steatosis greater than 20%, older donor age, retransplantation, renal insufficiency, and prolonged cold ischemia times (1). Recognition of PNF is an indication for prompt retransplantation. HAT complicates 7% of adult LTs (range 4% to 25%), and 10% to 40% of pediatric cases (2). Risk factors include technical and anatomic difficulties, including small size of donor hepatic artery and complex hepatic artery anastomosis. Clinical signs of HAT resemble PNF, also reflecting profound graft dysfunction, if HAT occurs in the first several days following LT. Color Doppler ultrasonography is performed to confirm blood flow in the hepatic artery. The sensitivity of ultrasonography is reported to be approximately 90% in detection of acute HAT but angiography may be needed for definitive diagnosis. Late complications of unrecognized HAT, reflect ischemia of the biliary tree and include biliary strictures and bilomas. In common with PNF, HAT in the early postoperative period is an indication for prompt retransplantation although occasionally surgical thrombectomy may be successful. Infectious precautions, including oral antibiotic prophylaxis for gut decontamination and intravenous antibiotics, are taken before the transplantation and in the operating room. Intravenous antibiotic prophylaxis should be continued for at least 24 hours after transplantation, and should cover a broad spectrum of organisms, specifically gram-positive skin flora and enteric gram-negative organisms. Opportunistic infections are not a major concern in the first few weeks following LT if graft function is good. Infections are typical of any patient recovering from major abdominal surgery, notably wound and pulmonary infections. Along with assessment of allograft function, routine ICU care including ventilatory management with weaning and pulmonary toilet as indicated. Other important issues at the bedside include monitoring of output from the Jackson-Pratt abdominal drains placed at the time of surgery to exclude a bile leak or intra-abdominal bleeding before their eventual removal, incentive spirometry once extubated, gradual advancement of oral intake as tolerated, and pain management. Once stable, transfer to a ward where the staff is experienced in the care of LT recipients is important for continuity of patient care. Therapeutic immunosuppression is divided into induction (initial immunosuppression) and maintenance immunosuppressive phases, with additional immunosuppression for treatment of acute cellular and chronic ductopenic rejection. A number of immunosuppressive agents are currently employed (3). Newer immunosuppressive agents have often undergone evaluation initially in renal transplant recipients, reflecting the greater need for effective antirejection regimens in other areas of solid organ transplantation. Although rejection cannot be discounted in LT, the more formidable threat to ultimate graft viability is recurrent disease. An uncomplicated episode of acute cellular rejection (ACR) conveys a survival advantage in many LT recipients reflecting a relatively well-preserved immune system in contrast to renal transplant recipients in whom it results in diminished graft survival (4). The primary goal of immunosuppression is to prevent graft rejection and loss; a secondary goal is to avoid the adverse consequences of antirejection therapy. Immunosuppression is initiated intraoperatively with a steroid bolus. Although regimens vary by center, steroids are continued at a high dose for the first several days following LT while the mainstay of modern immunosuppression, a calcineurin inhibitor CNI, is introduced within the first postoperative day. Increasingly mycophenolate mofetil is added to the regimen as an adjunct immunosuppressive agent (which can allow for calcineurin sparing) in the setting of preexisting renal insufficiency or acute oliguric renal failure. Rejection is generally not a concern for the first week to 10 days post-LT.

Floor Care Clinical care following transfer of patient to the floor is aimed at continued close monitoring of graft function, along with titration of immunosuppression into therapeutic range, wound care, early ambulation or physical therapy as tolerated, and patient and caregiver education.

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Graft function in the days subsequent to discharge from ICU should continue to improve with resolution of coagulopathy and biochemical dysfunction (Table 55.1). Some clues to a likelihood of continued early allograft dysfunction that may portend a poor worsened long-term patient and graft survival include recipient prothrombin time or bilirubin that stays persistently elevated, donor age greater than 50 years, cold ischemia time greater than 15 hours, and donor preprocurement acidosis (5). Rejection also becomes an increasing concern in this phase of post-LT period. Any significant elevation in liver enzymes should prompt a diagnostic P.1483 liver biopsy. Biopsy-proven acute rejection occurs in up to 75% of LT recipients, typically within the first year.(6). Balancing adequate immunosuppression with the side effects of the CNIs, especially renal toxicity, is important (Table 55.2). ACR occurs in up to 70% of liver transplant recipients in the first year, of these 68% had both biochemical and histologic abnormalities consistent with ACR, while 32% had only histologic findings on protocol biopsies, without biochemical abnormalities. The latter is of unclear significance (7). ACR becomes most frequent after the first week. Most patients are clinically asymptomatic despite early mild acute rejection; however, hepatomegaly and tenderness to palpation of the allograft can be seen in late or severe acute rejection. Elevations in total bilirubin, transaminase (aspartate transaminase [AST] and alanine transaminase [ALT]), γ-glutamyl transpeptidase (GGT), and/or alkaline phosphatase levels, after initial normalization post-LT, suggest, but are not specific for, ACR which requires confirmation by liver biopsy as histopathology remains the gold standard for its diagnosis. Rejection is suggested by the presence of portal inflammation, bile duct damage, and venous subendothelial infiltration by inflammatory cells (Table 55.3). In many cases, the presence of eosinophils can also be a helpful indication of acute rejection (8). However, cellular rejection can be difficult to distinguish from recurrent disease, especially recurrent hepatitis C infection, although the latter does not usually occur for at least several weeks post-LT. Importantly, treatment of apparent ACR with steroid boluses is a predictor of more severe recurrent hepatitis in recipients with hepatitis C virus (HCV) infection, so the distinction is not merely of academic interest (9). ACR is typically treated with increased immunosuppression, initially with a corticosteroid bolus and/or an increase in the dosage of maintenance immunosuppressant medication (such as tacrolimus) especially if blood trough levels are found to be subtherapeutic. Antilymphocyte therapy such as antithymocyte immunoglobulin or the monoclonal antibody OKT3 may be used in the setting of steroid refractory rejection.

Table 55.1. Graft Function and Dysfunction in the Liver Transplant Recipient

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Third to sixth month

First week

Second and third week

Third to twelfth week

Physiologic

Aminotransferase normalize INR diminishes to normal Discharge from intensive care unit

Continued improvement in hepatic and renal function Discharge from hospital

Normal liver chemistries

Normal liver function

Pathologic

Hyperacute rejection PNF HAT

Acute cellular rejection Impaired graft function

Acute cellular rejection Cytomegalovirus Recurrent HCV Delayed HAT

Recurrent HCV Biliary stricturing due to HAT Recurrent primary sclerosing

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cholangitis

INR, international normalized ratio; PNF, primary graft nonfunction; HAT, hepatic artery thrombosis; HCV, hepatitis C virus.

Table 55.2. Common Side Effects of Immunosuppression

Tacrolimus

Cyclosporine

Prednisone

Nephrotoxicity

Nephrotoxicity

Osteoporosis

Tremor

Tremor

Osteonecrosis

Hypertension

Hypertension

Diabetes

Headache

Headache

Hyperlipidemia

Gastrointestinal symptoms

Hirsutism

Hirsutism

Alopecia

Gingival hyperplasia

Hypertension

Diabetes

Cushingoid habitus

Cytomegalovirus (CMV) is a major cause of morbidity and mortality in the first 14 weeks after transplantation before effective routine prophylaxis against and was implicated in other adverse outcomes such as chronic rejection (CR) (10,11) Particularly at risk of primary CMV infection are seronegative recipients of allografts from seropositive donors. Other risk factors include retransplantation and the use of antilymphocyte antibodies. CMV infection may manifest as asymptomatic viremia or overt disease with multiorgan involvement of skin, gastrointestinal tract, and graft dysfunction. Intravenous ganciclovir (6 mg/kg/day) given for 100 days postoperatively reduced the risk of CMV infection to 5% to 10% (12). Recent studies comparing oral ganciclovir (after a 14 day intravenous induction) to intravenous ganciclovir until day 100 after transplant showed no statistical difference in 1 year CMV infection rates, obviating the need for long-term intravenous access (13). Clinical disease is generally treated with intravenous ganciclovir. Although resistant strains of CMV occur, clinical disease typically reflects inadequate prophylaxis rather than CMV resistance. Pneumocystis carinii (PCP) infection occurs in 6% to 20% of patients undergoing solid organ transplantation in the absence of prophylaxis. Trimethoprim-sulfamethoxazole (TMP/SMX) is effective in preventing P.1484 PCP and is generally given for 6 to 12 months after transplantation at the time of highest immunosuppression and greatest risk. Intolerance to TMP/SMX may then require second line

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agents including aerosolized pentamidine or atovaquone.

Table 55.3. Rejection Activity Index and Grading of Acute Liver Allograft Rejection

(A) Rejection Activity Index (RAI) Criteria that can be used to score liver allograft biopsies with acute rejection, as defined by the World Gastroenterology Consensus Document

Category

Criteria

Score

Portal

Mostly lymphocytic inflammation involving, but not

1

inflammation

noticeably expanding, a minority of the triads

Expansion of most or all of the triads, by a mixed

2

infiltrate containing lymphocytes with occasional blasts, neutrophils, and eosinophils

Marked expansion of most or all of the triads by a

3

mixed infiltrate containing numerous blasts and eosinophils with inflammatory spillover into the periportal parenchyma

Bile duct inflammation damage

A minority of the ducts are cuffed and infiltrated by inflammatory cells and show only mild reactive changes such as increased nuclear:cytoplasmic ratio of

1

the epithelial cells

Most or all of the ducts infiltrated by inflammatory cells; more than an occasional duct shows degenerative changes such as nuclear pleomorphism,

2

disordered polarity, and cytoplasmic vacuolization of the epithelium

Venous endothelial inflammation

As above for 2, with most or all of the ducts showing degenerative changes or focal lumenal disruption

3

Subendothelial lymphocytic infiltration involving some, but not most of the portal and/or hepatic venules

1

Subendothelial infiltration involving most or all of the portal and/or hepatic venules

2

As above for 2, with moderate or severe perivenular inflammation that extends into the perivenular parenchyma and is associated with perivenular hepatocyte necrosis

3

Total RAI Score = _/9

From (7a) Hepatology. Banff schema for grading liver allograft rejection: an international consensus document. 1997;25(3):658–663.

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(B) Grading of acute liver allograft rejection Global assessment of rejection grade made on a review of the biopsy and after the diagnosis of rejection has been established

Global assessment a

Criteria

Indeterminate

Portal inflammatory infiltrate that fails to meet the criteria for the diagnosis of acute rejection (see reference in subsequent text)

Mild

Rejection infiltrate in a minority of the triads, that is generally mild, and confined within the portal spaces

Moderate

Rejection infiltrate, expanding most or all of the triads

Severe

As in preceding text for moderate, with spillover into periportal areas and moderate to severe perivenular inflammation that extends into the hepatic parenchyma and is associated with perivenular hepatocyte necrosis

Verbal description of mild, moderate or severe acute rejection could also be labeled as Grade I, II and III, respectively. From (7a) Hepatology. Banff schema for grading liver allograft rejection: an

a

international consensus document. 1997;25(3):658–663

Neurologic dysfunction can present during this phase of hospitalization as acute delirium, seizures, hallucinations, and tremor. The differential diagnosis includes metabolic causes (uremia, electrolyte imbalance), infection, residual encephalopathy, and medication side effects. Steroids and CNIs have known neurologic side effects, and switching from tacrolimus to cyclosporine or adding an adjunct medication such as mycophenolate mofetil to reduce the CNI dose may be of benefit. Any localizing symptoms should be assessed with prompt imaging to rule out focal hemorrhage or infarct. Central pontine myelinosis (CPM) is a neurologic finding associated with variable symptoms that can include coma, dysarthria, dysphagia, ophthalmoplegia, quadriparesis, tremor, locked-in syndrome, and ataxia among others. Development of CPM can be associated with rapid sodium shifts in the perioperative period, which lead to intramyelinic edema and subsequently demyelination in the pons. CPM has been reported in 5% to 12% of orthotopic liver transplantation (OLT) autopsy series, however, is more rarely seen in clinical practice. Prevention includes minimizing serum sodium fluctuations and avoiding excessively high levels of CNIs. Mild to moderate ascites after transplantation is common but usually resolves over days to weeks. Conservative management with continued moderate salt restriction and the judicious use of diuretics as tolerated by renal function usually leads to fairly rapid resolution of the ascites. If large volume ascites persists, investigation should be initiated toward hepatic vein P.1485 and atrial pressure measurements to detect pressure gradients. Rodes et al. found that factors contributing to large volume ascites post-OLT included inferior vena cava preservation with piggyback technique, suggesting difficulty in graft blood outflow (14). Other medical issues during the course of hospitalization include the management of systemic hypertension and diabetes. Hypertension is the most common cardiovascular complication following liver transplantation occurring in up to 50% to 80% of recipients. The relative risk of ischemic cardiac events was 3.07 in allograft recipients compared to an age-matched population without transplantation (15). Mechanisms for hypertension include altered vascular

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reactivity and vasoconstriction related to CNIs, impaired glomerular filtration rate (GFR) and sodium excretion, and the effects of steroids. Treatment of hypertension should counteract sodium and water retention due to CNIs. A thiazide diuretic may be effective if used judiciously to volume depletion. Vasoconstriction due to CNI use is also a factor in systemic hypertension, so vasodilatation with a calcium channel blocker is appropriate first-line therapy. Diltiazem and verapamil increase the CNI levels and have more limited use than nifedipine. Angiotensin-converting enzyme (ACE) inhibitors, due to aggravation of renal dysfunction and hyperkalemia, are generally not recommended in the early post-transplantation course but may be useful in transplant recipients with diabetes, in the long term. Poorly responsive hypertension may require addition of a β-blocker or a centrally active agent such as clonidine. Impaired glucose tolerance and diabetes are common in patients with cirrhosis due to peripheral insulin resistance, which predisposes them to post-transplantation diabetes (PTDM). HCV infection also enhances the risk of PTDM. The diabetogenic effect of immunosuppressives, mainly tacrolimus and cyclosporine as well as that of corticosteroids, are important factors. Treatment of diabetes in OLT recipients is based on the same principles as in the nontransplant patient. Treatment with a regular insulin sliding scale while hospitalized to assess insulin needs, then discharge on oral medications and/or insulin is usual. Insulin requirements should lessen as reduction in corticosteroids and other immunosuppressive medications occurs. Diet, lifestyle modification, obesity reduction, and the continued use of insulin or oral hypoglycemic agents may be indicated; with glyburide being an initial choice if an oral agent is felt to be sufficient. Metformin is best avoided because of concern about lactic acidosis in the presence of renal dysfunction that is common in this population. Patient and caregiver education is the final key to a successful hospitalization for OLT. A thorough discussion with a member of the transplantation team on medication indications, side effects, and interactions is important in the assurance of patient compliance. Patients should be made aware of “warning signs” for which an immediate call to the transplantation center is warranted. Emphasis is placed on good general medical care, use of sunscreen because of an increased risk of cutaneous malignancies, and age appropriate health screening.

Early Clinic Visits Frequency of outpatient clinic visits vary, but usually are weekly in the first 1 to 2 months, biweekly thereafter, and monthly for up to 1 year. Goals of the clinic visit include assessment of the patient's overall health and well being, activities of daily living, medication compliance, and biochemical and immunosuppression monitoring. In the first weeks following transplantation, a continued low threshold for suspicion of rejection needs to be maintained, and liver biopsy has to be obtained for any significant elevation on serum aminotransferases. Elevations in bilirubin and/or alkaline phosphatase or features of obstruction on liver biopsy suggesting an obstructive clinical picture should prompt a cholangiogram. The cholangiogram may be performed through the T-tube, if present, or increasingly by magnetic resonance cholangiopancreatography (MRCP) if a Roux-en-Y anastomosis was performed. Endoscopic retrograde pancreatography (ERCP) may also be performed by experienced biliary endoscopists but risks of perforation or pancreatitis must be considered. Biliary imaging can distinguish between an anastomotic stricture versus the more worrisome intrahepatic biliary stricturing, which may reflect hepatic arterial occlusion leading to biliary ischemia or use of a suboptimal graft with, for instance, protracted cold ischemia. Anastomotic strictures are usually amenable to biliary stenting whereas intrahepatic stricturing may require retransplantation because of its frequent association with HAT or other graft dysfunctions and lack of success with stenting. Nonanastomotic strictures in addition to ischemia can reflect other problems such as prolonged cold ischemia time, ABO incompatibility, and more recently the use of organs procured for transplantation from non–heart beating donors. CMV infection should still be suspected if diarrhea or pneumonitis occur with fever and graft dysfunction, especially if prophylaxis has been discontinued. The diagnosis of CMV infection is confirmed by culture of tissue or blood with rapid tissue culture techniques using indirect immunofluorescence. Treatment is with high-dose ganciclovir. Immunosuppression levels continue to be monitored with fasting levels drawn of specific CNIs, such as cyclosporine or tacrolimus. Serum drug levels may vary based on diet and concomitant medication usage

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P.1486 and need to be adjusted accordingly. Duration of steroid taper varies by transplantation center, but most recipients are weaned to low or no steroids by 6 months post-OLT. Hyperlipidemia, with a mixed profile of elevated cholesterol and triglyceride levels, is noted in up to 30% of OLT recipients. Elevated lipid levels may be associated with allograft vasculopathy. The etiology of hyperlipidemia is multifactorial including obesity, preexisting disease, and medication induced. Cyclosporine causes inhibition of bile acid synthesis, and sirolimus and corticosteroids have been shown to cause dyslipidemia. Treatment of obesity and diabetes as well as dietary and lifestyle modifications are first-line measures. If serum lipid levels do not fall, 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors can be safely prescribed. Myositis, rhabdomyolysis, and hepatotoxicity are uncommon side effects. The choice of agent is dependent on cost, degree, and type of hyperlipidemia. Nicotinic acid, bile acid binders, and fibric acid derivatives are generally avoided because of their potential hepatotoxicity or interference with other medications. Importantly, many OLT recipients succumb to nonhepatic causes as time from transplantation increases, reflecting factors such as an increased risk of cardiovascular disease, neoplasia, and other factors such as calcineurin-induced renal failure (16). Meticulous attention to systemic hypertension and other risk factors for adverse outcomes therefore assume major significance in the care of the OLT recipient.

Late Clinic Visits After the first several weeks of close follow-up by the transplantation team, good communication with the primary care physician should lead to a smooth transition to long-term care. CR, although uncommon, usually occurs after the first 6 months. Patients with CR can be relatively asymptomatic but typically present with laboratory parameters of cholestasis, such as a rise in alkaline phosphatase, GGT, and/or total bilirubin levels. On biopsy, loss of small bile ducts and obliterative angiopathy are classic histologic features. Several risk factors contribute to CR. Almost all affected patients have had at least one episode of acute rejection. Other contributing factors are inadequate immunosuppression in the early postoperative phase, CMV infection, primary biliary cirrhosis (PBC), primary sclerosing cholangitis (PSC), or a history of autoimmune hepatitis (17). CR redevelops in as many as 90% of patients who undergo retransplantation for this reason (18). A number of reports have implicated interferon therapy for recurrent HCV infection in CR, as is discussed elsewhere in this book (see Chapter 58). Steroid boluses and antilymphocytic treatment, although efficacious in the treatment of acute rejection, have little effect in CR. Tacrolimus has proven to be the most effective treatment of CR, especially if the diagnosis of CR was made within 3 months of transplantation (19). Other important causes of late graft dysfunction include recurrence of the original liver disease as exemplified by HCV (see Chapter 58); however, nonviral diseases including cholestatic and autoimmune hepatitis can also recur. In PBC, biopsy features typical of the disease in the native liver are observed whereas in PSC, biliary stricturing reminiscent of disease in the absence of OLT can also occur. Although recurrence of the cholestatic liver diseases occur less frequently than HCV, and previously hepatitis B virus (HBV), at least some grafts are lost and with long-term follow-up about one fourth of patients who underwent transplantation for cholestatic disease experience clinically overt recurrence. Possible factors implicated in disease recurrence include tacrolimus-based immunosuppression in PBC and absence of colectomy in PSC. No definitive strategy to prevent or ameliorate recurrent disease has emerged. In contrast, recurrent autoimmune hepatitis with reappearance of autoantibodies is generally steroid responsive. A de novo form of autoimmune hepatitis, especially in the pediatric population, may be more difficult to control. Recurrent and de novo nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH) are also recognized. Osteopenia is common in patients with cirrhosis and typically is due to osteoporosis rather than osteomalacia, although the latter can occur in severely cholestatic patients. Factors implicated, apart from calcium and vitamin D deficiency include low muscle mass, immobility, long-term corticosteroid use, poor nutrition, and alcohol abuse. After transplantation, rapid bone loss occurs in the first 3 to 6 months, but ultimate recovery of bone mass can continue for up to 7 years after OLT. For patients awaiting OLT, serum calcium, phosphorus, thyroid

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function studies, and parathyroid hormone should be evaluated along with bone densitometry studies. In addition to calcium and vitamin D, calcitonin or bisphosphonates may be considered if bone density indicates osteoporosis or if long-term corticosteroids are used. Once weekly oral dosing with alendronate or risedronate is well tolerated and convenient. Skin cancer, lymphoma, and oropharyngeal cancer are more common in OLT recipients. Cigarette smoking is obviously prohibited. The patient should see a dermatologist on a regular basis. Patients with transplantation for PSC who have inflammatory bowel disease remain at high risk for colonic dysplasia and colon cancer, and require regular colonoscopy even in clinically quiescent disease. Beyond 6 months, post-OLT recipients should be vaccinated for influenza, pneumococcus, and tetanus. P.1487 Live vaccines like measles, mumps, and rubella, and live oral polio vaccine should not be given.

Annotated References Busuttil RW, Shaked A, Millis JM, et al. One thousand liver transplants. The lessons learned. Ann Surg 1994;219(5):490.

Quiroga J, Colina I, Demetris AJ, et al. Cause and timing of first allograft failure in orthotopic liver transplantation: a study of 177 consecutive patients. Hepatology 1991;14 (6):1054. With one of the largest early transplantation center experiences in the world, the authors described risks factors for primary graft nonfunction including older donor age, donor steatosis, and prolonged ischemia time. Calne RY, Rolles K, White DJ, et al. Cyclosporin a initially as the only immunosuppressant in 34 recipients of cadveric organs: 32 kidneys, 2 pancreases, and 2 livers. Lancet 1979;2 (8151):1033.

Starzl TE. History of liver and other splanchnic organ transplantation. In: Busuttil RW, Klintmalm GB, eds. Transplantation of the liver. Philadelphia, PA: WB Saunders, 1996:3.

Starzl TE, Marchioro TL, Von Kaulla KN, et al. Homotransplantation of the liver in humans. Surg Gynecol Obstet 1963;117:659.

Welch CS. A note on transplantation of the whole liver in dogs. Transplant Bull 1955;2:54. One of the first studies showing efficacy of the calcineurin inhibitor, cyclosporine, in preventing rejection in transplant recipients. Subsequently, 1-year survival rates improved from approximately 30% to greater than 70% in the following decade after its introduction and use. Demetris A, Adams D, Bellamy C, et al. Update of the international Banff schema for liver allograft rejection: working recommendations for the histopathologic staging and reporting of chronic rejection. An international panel. Hepatology 2000;31(3)792. Criteria previously described by this panel to define and standardize the histological criteria for acute cellular rejection in the liver graft proved clinically useful and widely applicable. The 5 t h Banff Conference report defines the histologic criteria for diagnosis and staging of chronic rejection. The US Multicenter FK 506 Liver Study Group. A comparison of tacrolimus (FK506) and cyclosporine for immunosuppression for liver transplantation. N Engl J Med 1994;331

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(17):1110. Further advances in immunosuppression, with the introduction of tacrolimus with lower rates of acute cellular rejection and reduced steroid requirement.

References 1. Ploeg RJ, D’Alessandro AM, Knechtle SJ, et al. Risk factors for primary dysfunction after liver transplant—a multivariate analysis. Transplantation 1993;55(4):807–813.

2. Pastacaldi S, Teixeira R, Montalto P, et al. Hepatic artery thrombosis after orthotopic liver transplantation: a review of nonsurgical causes. Liver Transpl 2001;7(2):75–81.

3. Everson GT, Trotter JF, Kugelmas M, et al. Immunosuppression in liver transplantation. Minerva Chir 2003;58(5):725–740.

4. Weisner RH, Demetris AJ, Belle SH, et al. Acute hepatic allograft rejection: incidence, risk factors, and impact on outcome. Hepatology 1998;28(3):638–645.

5. Deschênes M, Belle SH, Krom RAF, et al. Early allograft dysfunction after liver transplantation: a definition and predictors of outcome. Transplantation 1998;66(3):302– 310.

6. Weisner RH. A long term comparison of tacrolimus vs. cyclosporine in liver transplantation. Transplantation 1998;66:493.

7. Bartlett AS, Ramadas R, Furness S, et al. The natural history of acute histologic rejection without biochemical graft dysfunction in orthotopic liver transplantation: a systematic review. Liver Transpl 2002;8(12):1147–1153.

8. Hepatology. Banff schema for grading liver allograft rejection: an international consensus document. 1997;25(3):658–663.

9. Nagral A, BenAri Z, Dhillon AP, et al. Eosinophils in acute cellular rejection in liver allografts. Liver Transpl Surg 1998;4(5):355–362.

10. Everson GT. Impact of immunosuppressive therapy on recurrence of hepatitis C. Liver Transpl 2002;8(10 Suppl 1):S19–S27.

11. Paya CV, Weisner RH, Hermans PE, et al. Risk factors for cytomegalovirus and severe bacterial infections following liver transplantation: a prospective multivariate timedependent analysis. J Hepatol 1993;18:185–195.

12. O’Grady JG, Alexander GF, Sutherland S, et al. CMV infection and donor/recipients HLA antigens: interdependent cofactors in the pathogenesis of vanishing bile duct syndrome after liver transplantation. Lancet 1988;ii:302–305.

13. Winston DJ, Wirin D, Shaked A, et al. Randomized comparison of ganciclovir and highdose acyclovir for long-term cytomegalovirus prophylaxis in liver-transplant recipients. Lancet 1995;346:69.

14. Winston DJ, Busuttil RW. Randomized controlled trial of sequential tranvenous and oral ganciclovir versus prolonged intravenous ganciclovir for long-term prophylaxis of cytomegalovirus disease in high-risk cytomegalovirus-seronegative liver transplant

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recipients with cytomegalovirus-seropositive donors. Transplantation 2004;77(2):305–308.

15. Cirera I, Navasa M, Rimola A, et al. Ascites after liver transplantation. Liver Transpl 2000;6(2):157–162.

16. Johnston S, Morris JK, Cramb R, et al. Cardiovascular morbidity and mortality after orthotopic liver transplantation. Transplantation 2002;73(6):901–906.

17. Pruthi J, Medkiff KA, Esrason KT, et al. Analysis of causes of death in liver transplant recipients who survived more than 3 years. Liver Transpl 2001;7(9):811–815.

18. Wiesner RH, Ludwig J, Krom RA, et al. Treatment of early cellular rejection following liver transplantation with intravenous methylprednisolone. The effect of dose on response. Transplantation 1994;58:1053–1056.

19. van Hoek B, Wiesner RH, Krom RA, et al. Severe ductopenic rejection following liver transplantation: incidence, time of onset, risk factors, treatment, and outcome. Semin Liver Dis 1992;12(1):41–50.

20. Sher LS, Consenza CA, Michel J, et al. Efficacy of tacrolimus as rescue therapy for chronic rejection in orthotopic liver transplantation: a report of the US Multicenter Liver Study Group. Transplantation 1997;64(2):258–263.

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Editors: Title:



Copyright ©2007 Lippincott Williams & Wilkins > Table of Contents > Volume 2 > Section XII - Elements of Liver Transplantation > Chapter 56 - The Long-Term Care of Transplanted Patient

Chapter 56 The Long-Term Care of Transplanted Patient Timothy M. Mccashland

Key Concepts z

Common medical problems in the long-term liver transplant recipient include obesity, osteoporosis, cardiovascular disease (CVD), and diabetes mellitus, all of which may result in increased morbidity and mortality.

z

Technical related problems of biliary complications may be corrected by endoscopic therapy. However, living-related biliary complications are common both in the donor and the recipient and require a multidisciplinary team approach.

z

Common causes of deaths in survivors for more than 1 year include development of de novo malignancy, cardiovascular causes, renal failure, and recurrent disease. Diligent surveillance for these diseases may lead to early detection and lower morbidity.

z

Renal impairment is common in long-term survivors. Development of end-stage renal disease is reported in up to 18%, with markedly decreased survival in these patients.

z

Recurrent hepatitis C leading to impaired allograft function is common. Treatment with combination therapy of pegylated interferon and ribavirin results in 20% to 35% clearance of the virus, but often requires growth factors and meticulous follow-up.

The traditional model of care in most transplantation centers is for the transplantation surgeon to manage the immediate postoperative care, with gradual incorporation of transplantation hepatologists and primary care physicians (1,2). With increasing success in liver transplantation, the need to manage these patients beyond the initial 6-month period often requires multiple providers and a larger commitment to prevent medical complications. Distinct differences exist among transplantation centers as to who becomes the primary physician in charge of long-term management (3). The transplantation hepatologist can provide expertise to encompass the overall care of common medical conditions, gastrointestinal- and transplantation-related problems. In a survey of transplantation centers, 40% of programs regarded the transplantation hepatologist as the primary care provider. An equal 40% had the primary care physician (family medicine/internist) as the principal provider of long-term management (3). Therefore, the management of long-term care seems to become the responsibility of internist/family physicians and transplantation hepatologists. Interestingly, transplantation surgeons and referring gastroenterologists were not expected to provide much input. Transplantation centers do not want primary care physicians managing immunosuppression, acute allograft rejection, recurrent disease, and biliary complications. Several comprehensive reviews of medical complications and management of liver transplant recipients have been published previously (4,5,6,7,8). In 2006, the American Board of Internal Medicine will initiate a subspecialty board certification in transplantation hepatology of which 25% of the test will be related to the management of long-term care (9). This chapter will address management of long-term care of the liver transplant recipient divided into topics of quality of life (QOL), causes of death in long-term survivors, medical P.1490 problems (obesity, gout, vaccines, bone disease, cardiovascular problems, diabetes

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mellitus), inflammatory bowel disease (IBD), pregnancy, and transplantation-related diseases (biliary complications, de novo neoplasia, renal dysfunction).

Quality of Life The immediate goal of liver transplantation is to improve survival of the recipient. However, the secondary goal is to improve the QOL and return the patient to a productive life. Numerous studies have been published on this topic (10,11). Diverse results are likely due to different assessment tools and methods. Early studies with follow-up of less than 2 years noted liver recipients achieve very satisfactory levels of health-related quality of life (HRQOL). However, the HRQOL levels were below that of the general population (10). A meta-analysis confirmed these early findings (11). A prospective multicenter study assessing pretransplantation and post-transplantation HRQOL using the 36-item short-form health survey (SF-36) and EuroQol (EQ-5D) instruments with follow-up of 2 years showed a significant improvement in all dimensions of the SF-36 and role-emotion dimensions of the EQ-5D scores (12). Longer survival after transplantation, younger age, and patients from larger transplantation centers were independent predictive variables of higher QOL scores. Panter et al. studied patients up to 5 years after transplantation and found that the number of comorbid conditions and participation in physical activity were significant independent contributors to improved HRQOL (13). A recent French study compared QOL in survivors beyond 10 years after liver, kidney, and heart transplantation with the general population (14). The National Institute of Diabetes and Digestive and Kidney Disease transplantation QOL questionnaire was used to assess 315 patients (liver 126). Perceived physical health, personal function, and social and role functions were similar in the transplantation patients, but lower than the general public. Perceived psychological health was better than the general public in liver and heart transplant recipients but lower in kidney recipients. The QOL beyond 10 years in liver transplant recipients is similar to the general public according to this study. Moore et al. in a large, single-center study, found that functional performance and HRQOL were not affected by donor, recipient, or technical characteristics (15). Chronic immunosuppression, while it may contribute to some complications after transplantation, had little impact on HRQOL in one study (16). Jennings et al. noted no difference in QOL between Laennec's cirrhosis and non-Laennec's patients with follow-up to 5 years (17). However, another study at a mean follow-up of 4 years found impaired lower global QOL, physical functioning in hepatitis C patients with recurrent disease (18). Psychological improvement after liver transplantation has also been shown to begin immediately after surgery. More recent long-term studies tend to show that depressioncoping skills, anxiety, and social environments are more relevant in liver transplant recipient's QOL than other somatic factors (19,20,21). Not surprisingly, elevated levels of anxiety and neuroticism before transplantation were associated with worse psychological health after transplantation (22). A concerning and interesting investigation by Lewis et al. using multiple tests in cognitive function in 36 patients 10 years after transplantation showed that the patients scored significantly lower than healthy controls across a wide range of cognitive functions (23). Unfortunately, the reason for this lower function is unknown and needs further study. Blanch et al. using the psychosocial-adjustment-to-illness scale found that women had poorer adjustment to orthotopic liver transplantation (OLT) than men; the proportion of women with poor adjustment was higher (31.5% vs. 16.7%) (21). Women showed a greater dysfunction in health care orientation, sexual relations, and extended family relationships and psychological distress. Therefore, women may need more psychological intervention after transplantation than men. Therefore, psychological factors are important contributors to QOL issues in the long-term management of liver transplant recipients.

Causes of Death in Long-Term Survivors According to the United Network of Organ Sharing (UNOS) database, the overall 1-, 3- and 5-year survival rates for liver transplant recipients are 82.5%, 73.5%, and 67.5% respectively (24). The well-known causes of death during the first year after transplantation include graft dysfunction, technical problems, and infections (25). There have been several studies looking at the cause of death in patients who have survived at least 1 year. These studies have generally defined the patient with survival greater than 1 year as a long-term

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survivor (26,27). A few studies have looked at mortality after 3 or 5 years (28,29,30,31). The common evolving theme is that mortality occurring more than 1 year after liver transplantation in adults includes malignancy (recurrent and de novo), recurrence disease (especially hepatitis C virus [HCV] infection), cardiovascular events, chronic rejection, and less frequently infections and chronic renal failure (CRF). Table 56.1 illustrates the common causes of death in patients having survival greater than 1 year.

Table 56.1. Long-Term Causes of Death Post–Liver T

Number of

Author site

patients

F/U

Years

died after 1

years

with

Recurrent

study

year

mean

malignancy

disease

Astar S, et

1982–

al.

1993

London,

36/494

(1–10)

(7.5%)

Patients Cardiova

10 (28%)

3 (8%)

5 (14%)

HCC 5

HBV 3

MI 3

Canada Leuk 2

Aneuys 2

Lymp 1

Panc 1

Cca 1

Janin A, et

1981–

al.

1998

Pittsburgh

Rabkin J, et

1991–

al.

2000

Oregon

1,240/4,000

9.4

140

Unknown

91 (3.1%

4 (10%)

(5.4%)

(31%)

(2–18)

40/459

3.4

9 (23%)

8 (20%)

(9.6%)

(1–8.6)

HCC 3

HCV 7

Cca 2

PSC 1

Lung 2

Renal 1

PTLD 1

Neuberger J

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5

19%

22%

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Birmingham,

UK

Sudan D, et

Unknown

127/686

5.2

22 (17%)

Unknown

25 (20%

Pruthi J, et

1984–

38/399

Unknown

17 (44%)

9 (24%)

8 (21%)

al.

2001

S. Cal and

PTLD 8

HCV 8

MI 6

British

Lung 3

Etoh 1

CHF 2

15

27

18 (20%

(17.5%)

(30%)

al.

Nebraska

Columbia Colon 2

Gastric 1

Breast 1

Adeno 1

Leuk 1

Voght D, et

1984–

al.

2001

88/433

5.6

Cleveland

HCV 16

HBV 5

Etoh 3

PSC 2

PBC 1

Moreno

1986–

Planus JM,

1996

46/183

Unknown

14 (37%)

15

3 (6%)

(32%)

et al.

Madrid

&u&

>1 y

HCC 5

HCV 12

MI 3

&w&bPage

Cca 2

HBV 3

Gastric 2 Ampul 1 Esoph 1 lymph 1 Prostate 1 Colon 1

HCC, hepatocellular carcinoma; Leuk, leukemia; Lymph, lymphoma; Panc, pancreas cancer; Cca myocardial infarction; Aneuys, aneurysm; PTLD, post-transplant lymphoproliferative disorder; P adenocarcinoma of unknown etiology; HCV, hepatitis C virus; Etoh, alcoholic liver disease; CHF, cirrhosis; Ampul, ampullary carcinoma; Esoph, esophageal carcinoma.

P.1491 P.1492 P.1493 Recommendations

z

Recognition, prevention and surveillance for common causes of late mortality are imperative to improve the survival of this patient population.

Medical Care Obesity Obesity is a major health problem in the United States In the NHANES III study, 22.5% of the general public had a body mass index (BMI) of greater than 30 kg/m 2 . Weight gain is also common after liver transplantation. In a large cohort study, 21.6% of nonobese patients become obese in the first 2 years following transplantation (32). The most recent study noted that by 1 and 3 years post-transplantation, 24% and 31% of patients had a BMI greater than 30 kg/m 2 (33). Predictive factors included age greater than 50 years and pretransplantation BMI greater than 30. Another study reports development of obesity after transplantation in up to 60% of patients (34). Appetite stimulation caused by corticosteroids, change to a less restrictive diet, lack of exercise, and higher cumulative doses of prednisone lead to increased weight. An early study from Virginia, reported that severely obese patients had greater transfusion requirements, higher wound infections, and higher rate of death due to multiorgan failure (35). Nair et al. in a single-center study from Johns Hopkins University, evaluated 121 patients to compare outcomes in moderate and severely obese recipients versus nonobese recipients. Postoperative complications of respiratory failure (23% vs. 3%) and systemic vascular complications (14% vs. 2%) were much higher in the severely obese group (36). The length of hospitalization and total hospital costs were higher in severely obese patients compared to nonobese patients. The same investigators, using the UNOS database, assessed the morbidity and mortality in obese patients after liver transplantation (37). Primary graft nonfunction and immediate, 1year, and 2-year mortality were significantly higher in the morbidly obese group. Five-year mortality was higher in the severely obese (28%) and morbidly obese patients (27%) mainly due to infections and cardiovascular events. This study has led many centers to institute weight-restriction guidelines for liver transplantation. Interestingly, no studies exist on the success of weight loss after transplantation, either by diet or by obesity surgery. The National Heart, Lung and Blood Institute and National Institute of Diabetes and Digestive and Kidney Diseases guidelines for obesity recommend a target of 10% of baseline weight at a weight loss rate of 1 to 2 lb/week (38). Recommendations

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z

Yearly evaluation for weight gain.

z

If obesity develops, target weight loss of 1 to 2 lb/week. This requires multiple clinical visits and the supervision of a nutritionist.

Gout Hyperuricemia is a common disorder associated with liver transplantation (39,40). Calcineurin inhibitor immunosuppressant medications impair the excretion of uric acid (41). Neal et al. in a study of 134 consecutive liver transplant recipients, found that 47% of patients had hyperuricemia (39). The levels correlated with renal dysfunction. Interestingly, only 6% developed gout located in the wrist, knees, ankle, or elbow at a mean of 25 months after transplantation. All those treated with allopurinol had resolution of their symptoms. In another study, hyperuricemia was present in 85% of patients, with only 3% developing gout (40). Therefore, with the incidence of gout being quite low, treatment of isolated hyperuremia with allopurinol is not likely needed. The management of gout in these patients is potentially complicated by interactions of immunosuppressants and renal insufficiency. The combined use of azathioprine and allopurinol may lead to myelosuppression. Extreme care should be used with this combination. Recommendations

z

Allopurinol 100 mg/day, for patients with a history of gout and hyperuricemia.

z

Acute gout may be treated with colchicine, 0.6 mg every 2 hours up to 5 doses.

z

If symptoms persist, a trial of prednisone tapered over 1 week may be helpful.

Vaccines Immunosuppressed liver transplant recipients are at risk for infections, even many years after transplantation. Influenza poses a yearly risk. Previously published studies reported influenza vaccination response in adult liver transplant recipients to be from 50% to 95% seroconversion (42,43,44). These authors recommended a second dose to increase response rates. Soesman et al. found an increase of 20% in response rate with this strategy (44). Duchini et al. studied 20 post-transplant recipients at baseline and 6 weeks after vaccination (45). Side effects were well tolerated, but all had significantly lower titers than healthy individuals. In 1996, the Advisory Committee on Immunization Practices recommended all patients with chronic liver disease be vaccinated for hepatitis A virus (HAV). P.1494 Unfortunately, some patients are not vaccinated pretransplantation and may require the vaccine after transplantation. In a liver or renal transplant recipient study, Stark et al. found a seroconversion rate of 97% for HAV vaccination, but unfortunately found a rapid decline in antibody titers (46). Furthermore, only 39% of cyclosporine-treated patients had protective antibody titers versus 79% of tacrolimus-treated patients. A Mayo Clinic study of 39 patients evaluated HAV seroconversion rates at 1 and 7 months after the first dose utilizing two standard doses given at 6 months apart (47). Seroconversion rates were dramatically lower in the OLT patients compared to patients with chronic liver disease and healthy controls: 1 month (8% vs. 83% vs. 93%) and 6 months (21% vs. 97% vs. 98%). The few responders were much longer away from transplantation (average 75 months) than nonresponders, which may be related to higher immunosuppression at time of vaccination. Prevention of hepatitis B after liver transplantation is becoming less difficult with the use of hepatitis B immunoglobulin (HBIG) and nucleoside analog medications. Several investigators have tried hepatitis B vaccination as another alternative (48,49,50). Sanchez-Fueyo et al. in a pilot trial of recombinant hepatitis B virus (HBV) vaccine in liver transplant recipients reported anti-HBs titers greater than 10 IU/L in 14 of 17 patients. However, as described in an editorial, the patients were atypical in being many months removed from transplantation (48). The Berlin group evaluated antibody response to hepatitis B surface antigen in 10

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patients 2 years after transplantation (50). In contrast to other studies, patients were continued on HBIG during the study. They additionally received 20 µg of recombinant HBV antigen with a novel adjuvant (monophosphoryl lipid A) at weeks 0, 2, 4, 16, and 18. Five of ten patients developed antibody titers greater than 500 IU/L. We have previously reported on pneumococcal vaccination before transplantation but to our best knowledge no study has been performed on pneumococcal vaccine response in patient after transplantation (51). Recommendations

z

Yearly influenza vaccination of liver transplant recipients.

z

All personnel associated with care of liver transplant recipients should receive the annual influenza vaccination.

z

Vaccinate before liver transplantation if possible for HAV.

z

If unvaccinated for HAV before transplantation, consider vaccination, however, response rate will be better after 1 year removed from transplantation.

z

Discontinuation of passive immunoprophylaxis of HBIG with HBV vaccination has not become common practice. Large multicenter trials need to be performed to address this issue.

Bone Disease Osteoporosis is characterized by reduced bone mass and altered architecture increasing the risk of fracture typically in the spine, hip, or wrist areas (52). Many patients may have severe osteoporosis due to their chronic liver disease, especially cholestatic liver diseases. Early studies report immediate bone loss after transplantation with the nadir of bone mineral density (BMD) being around 6 months after transplantation with gradual recovery (53,54,55). Feller et al. noted in 28 patients that spine BMD had returned to pretransplantation levels by a mean of 85 months (56). However, another study did not show any improvement in the BMD of the proximal femur 36 months after transplantation (57). Guichelaar et al. reported gradual improvement of osteoporosis with follow-up to 7 years post-transplantation (58). Hamburg et al. reported that lumbar bone density increased in the second year after transplantation, stabilizing thereafter with follow-up to 15 years (59). Fractures are common in the high-risk group, most commonly in the hip, pelvis, spine, ribs, and wrist with frequently reported risks ranging from 5% to 35% (60,61). Haagsma et al. in a prospective study of 36 adult patients reported development of vertebral fractures in 38% of patients within 6 months of transplantation (62). A more recent prospective study by Hardinger et al. from St. Louis followed up 153 patients over 10 years (63). The prevalence of symptomatic fractures was 15% at a mean of 2.2 years post-transplantation. The only factor associated with risk of fracture was being female. Age, time from transplantation, race, menopause, renal insufficiency, family history of osteoporosis, BMD, and T score did not predict either osteoporosis or fractures after liver transplantation. Others have found older age (64), vertebral fracture before transplantation (61), cholestatic liver disease (60), and smoking (61) to be risks for fractures. Immunosuppressive medications are also proposed to contribute to osteoporosis. Glucocorticoids increase bone resorption by inhibition of osteoblast activity even at low doses of less than 7.5 mg per day (65). Cyclosporine has been shown to increase osteoporosis risk in renal transplant recipients (66). A histomorphometric analysis of 33 patients after liver transplantation by the Mayo Clinic suggested that patients with tacrolimus therapy have earlier recovery of bone formation and trabecular structure by 4 months compared to cyclosporine-treated patients (67). The role of secondary hyperparathyroidism remains controversial in this patient population with small increases in parathyroid levels within a few months of transplantation (68). P.1495

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Vitamin D deficiency is not rare in patients with chronic liver disease and Feller et al. demonstrated a rapid rise in 25-hydroxyvitamin D levels after transplantation (56). Treatment of osteoporosis after liver transplantation has usually been reported in small uncontrolled series. Velero et al. noted increased BMD in 40 patients treated with calcitonin (69). Whereas, Hay et al. found subcutaneous calcitonin of 100 IU/day ineffective in preventing fractures in a subset of patients undergoing transplantation for primary biliary cirrhosis (PBC) or primary sclerosing cholangitis (PSC) (70). Neuhaus et al. found improvement in BMD with daily doses of calcitriol, calcium, and sodium flouride (71). Two studies report on the use of IV pamidronate but showed little efficacy in preventing fractures (72,73). Interestingly, no data for oral bisphosphonates has been reported. Two comprehensive reviews by Crippin and Compston provide excellent guidelines on management of osteoporosis in liver transplant recipients (74,75). Recommendations

z

Pretransplantation evaluation with dual energy x-ray absorptiometry (DEXA) bone scan, serum tests of calcium, phosphorous, parathyroid hormone level, testosterone (men), estradiol (women), and α 25-hydroxyvitamin D levels.

z

Treatment of all patients with 1,500 mg of calcium/day and correction of any deficiencies.

z

If severe osteoporosis is noted by a T score greater than 2 SD below normal, then consider starting oral bisphosphonates.

z

Those under treatment for osteoporosis should have yearly DEXA, measurement of calcium, phosphorous, and thyroid function.

Cardiovascular Complications Established risk factors for development of cardiovascular disease (CVD) in liver transplant recipients include hypertension, hyperlipidemia, hyperhomocysteinemia, diabetes, renal insufficiency, obesity, family history of CVD, advanced age, African American race, male gender, tobacco abuse, and immunosuppressive medications (76,77,78,79,80,81) (Table 56.2). Remarkably, the extent of morbidity and mortality related to CVD remains controversial (79). In an early study from the United Kingdom, 110 consecutive patients were studied, the relative risk for cardiovascular deaths was two and half times greater as compared to age-matched population without transplantation using the Framingham risk score (77).In contrast, a Spanish study, found that the prevalence of hypertension, diabetes, hypercholesterolemia, and hypertriglyceridemia was lower at 5 years after transplantation compared to 1 and 3 years after transplantation and no different from the general Spanish population (80). Neal et al. in a comprehensive study of cardiovascular complications from the United Kingdom looked at the prevalence of risk factors for coronary heart disease and the effect on the predicted 10-year risk of developing coronary heart disease and incidence of cardiovascular events (82). One hundred and eighty-one patients were studied with most of them treated with cyclosporine. The 10-year predicted risk of CVD increased to 11.5% compared to 6.9% before transplantation and matched the control population of 7% at 10 years. Compared to matched controls, the incidence ratios of myocardial infraction and stroke were 0.55 and 1.45. Therefore, by 10 years the mortality associated with CVD was similar to that of the general population. Hyperlipidemia is common after liver transplantation (Table 56.2). Mixed hyperlipidemia (types 2a, 2b, and 4) with high cholesterol and triglyceride levels is the common pattern after transplantation. The etiology of hyperlipidemia is multifactoral (79). Steroids increase secretion of very low-density lipoprotein (LDL) and conversion of LDL. Cyclosporine inhibits 26-hydroxylase reducing the transport of cholesterol into bile, and binds to LDL receptor increasing the levels of LDL cholesterol (83). Tacrolimus in several studies has been noted to cause a lower incidence of dyslipidemia than cyclosporine (84,85). A study by investigators in Philadelphia, in converting patients from cyclosporine to tacrolimus monotherapy found that mean cholesterol levels decreased from 251 to 202 mg/dL and

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triglycerides decreased from 300 to 207 mg/dL (86). Several studies have evaluated dyslipidemia with sirolimus therapy in liver transplantation (87,88,89). In 57 patients treated with a combination of cyclosporine or tacrolimus with sirolimus Trotter et al. found hypercholesterolemia and hypertriglyceridemia were more common in the combination of cyclosporine and sirolimus than tacrolimus (hypercholesterol, 30% vs. 6%, hypertriglycerides, 18% vs. 3%) (87). Whereas in a more recent study of patients receiving sirolimus and tacrolimus for a mean of 57 months after transplantation compared to a group of tacrolimus monotherapy or in combination with mycophenolate mofetil, hypercholesterolemia and hypertriglyceridemia were similar (hypercholesterol, 15% vs. 9%, hypertriglycerides, 10% vs. 9%) (88). The proposed mechanism of sirolimus-induced hyperlipidemia is thought to be related to elevated apoCIII levels which inhibit lipoprotein lipase activity (90). Surprisingly, little data exists on use of statins for hyperlipidemia in liver transplant recipients. In a small study of 16 patients, cerivastatin and pravastatin decreased cholesterol by 21% and 15%, and LDL by 27% and 17% (91). Our center uses atorvastriatin because it is more potent and treats both cholesterol and triglycerides. Hypertension early after transplantation is almost universal, likely due to high vascular volume and high P.1496 P.1497 levels of calcineurin inhibitors, which reduce endothelial release of vasodilating factors (nitric oxide and prostacyclin) and increase the release of vasoconstrictor factors (endothelin and thromboxane) (92). Neal et al. found an increase in plasma endothelin levels and increases in arterial stiffness associated with hypertension (93). Earlier hypertension studies within the first year noted hypertension ranging from 17% to 82% (76,77,78). In a large European study at 6 months after transplantation, 26% of cyclosporine-treated patients and 17% of tacrolimus-treated patients had hypertension (94). More recent studies using a standard definition of hypertension reading greater than 140/85, reported that incidence at 3 months was 82% in cyclosporine patients and 32% in tacrolimus patients, and at 6 months 50% of patients were hypertensive (93). In studies with longer follow-up from 3 to 5 years after transplantation, overall incidence was around 50%. Detailed analysis in the Rabkin et al. study noted that 58% required a single antihypertensive agent, 29% required two agents, and 10% needed three agents (95). Galioto et al. found that nifedipine was effective in only 22% of patients, whereas 33% of carvedilol treated patients after liver transplantation responded (96). In a large study, Neal et al. reported that 46% of patients responded to amlodipine, with a decrease in systolic blood pressure from 154 mm Hg to 130 mm Hg (97). Patients unresponsive or intolerant to amlodipine were randomized to bioprolol or lisinopril. Lisinopril was successful in 84% of patients, reducing the systolic blood pressure from 154 mm Hg to 130 mm Hg.

Table 56.2. Cardiovascular Risk

F/U time from

Author Varo E, et

Percentage

Number

orthotopic

with

Percentage with

of

liver

hypertension

hypercholesterolemia

patients

transplantation

(%)

(%)

184

4.2 y

82 csa

Perc hypert

15

Unknow

34

11

al.

Spain 2002

FernandezMaranda C, et al.

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32 fk

116

5 y

49

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Spain 2002

Rabkin J,

87

3 y

62 csa

10

Unknow

et al.

Oregon

38 fk

2002

Johnson S,

110

3.9 y

63

44

Unknow

181

10 y

83 csa

59

41

et al.

London 2002

Neal D, et al.

Cambridge

67 fk

2004

Csa, cyclosporine; fk, tacrolimus.

Recommendations

z

Monitor fasting lipid profiles at 6 months and 1 year post-transplantation, then annually.

z

Attempt to attain total cholesterol levels less than 200 mg/dL, LDL levels less than 130 mg/dL, and normal triglycerides levels after transplantation.

z

First-line treatment should be dietary modification in accordance with the American Heart Diet.

z

If unsuccessful, 3-hydroxy-3methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) are to be used.

z

Early treatment of hypertension incorporates the use of diuretics, clonidine, or calcium channel blockers.

z

Diltiazem and verapamil can alter cyclosporine or tacrolimus levels, therefore are rarely used.

z

Angiotensin-converting enzyme inhibitors especially in patients with diabetes are a good choice for treatment of hypertension.

Diabetes The prevalence of diabetes in candidates for liver transplantation has ranged from 4% to 13% in previous studies (98,99). In a prospective study of 115 liver transplantation candidates, a group from Spain describes 25% of patients having impaired glucose tolerance and 53% as having diabetes by oral glucose tolerance test (100). Therefore, many patients are at risk of worsening diabetes after transplantation. Immunosuppressive medications are diabetogenic. Corticosteroids induce insulin resistance. Calcineurin inhibitors decrease insulin synthesis and secretion and induce insulin resistance (101). Cyclosporine and tacrolimus appear to have the same diabetic risk, although some have noted a higher risk

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with tacrolimus (102,103,104). Other immunosuppression medications including azathioprine, myophenolate mofetil, and sirolimus do not induce diabetes. Several risk factors for development of new-onset diabetes after transplantation have been recently characterized. A family history of diabetes among first degree relatives and those of Hispanic or African American ethnicity indicate a greater risk (105,106). Age above 40 years, obesity, and many episodes of steroid resistant rejections are also thought to be risks (106,107,108,109). In a large Canadian study, new-onset diabetes was associated only with transplantation for hepatitis C (odds ratio [OR] 4.12) (110). In the multicenter NIDDK-Liver Transplant Database, hepatitis C was also found to be predictive of transient diabetes, but not persistent diabetes after liver transplantation (109). In a small French study, alcoholic cirrhosis and male gender were independent predictors of new-onset diabetes (107). The incidence (4% to 38%) of new-onset diabetes after liver transplantation has been variously reported because of terms of definition, duration of follow-up, and changing criteria of diabetes. John and Thuluvath from Johns Hopkins University found that 10.5% of post–transplantation patients developed new-onset diabetes, of whom 18 were insulin dependent and 28 were treated by oral hypoglycemic medications (111). In another large single-center study, 37.7% of patients developed new-onset diabetes, 28% had transient diabetes and 9% had persistent diabetes (98). Using the UNOS database, Yoo et al. that found 7.6% were patients with type 1 diabetes and another 7.6% were patients with type 2 diabetes at 1 year after transplantation (112). Morbidity has been reported as similar among nondiabetic and diabetic patients (113). However, Khalili et al. reported that the overall infectious episodes in the presence of diabetes were fivefold higher (109). Higher morbidity in diabetic patients versus nondiabetic patients of cardiac episodes (48% vs. 24%), major infections (41% vs. 25%), minor infections (28% vs. 5%), neurologic (22% vs. 9%), and neuropsychiatric (22% vs. 6%) episodes were seen in the Baltimore study (111). Two studies found that survival was not worse in diabetic patients (100,114). In contrast, the UNOS P.1498 database study reported that 5-year patient survival was lower in patients with type I (insulin dependent diabetes) compared to those without diabetes (63% vs. 75%) (112). Patients with diet-controlled diabetes had a minimally decreased 5-year survival compared to nondiabetic patients. Furthermore, patients with type 1 diabetes or coronary artery disease were 40% more likely to die within 5 years of transplantation compared to those without these risk factors. A German study had similar poor 5-year survival in patients with type 1 diabetes (104). Consensus guidelines on new-onset diabetes after transplantation have been developed on the basis of definitions from the American Diabetes Association, World Health Organization, and American College of Endocrinology (115). Recommendations

z

Management of patients who develop new-onset diabetes is similar to recommendations of patients with type 2 diabetes.

z

Those with a Hemoglobin A1C level greater than 6.5% should be started on treatment.

z

Initial treatment is lifestyle modifications (exercise, weight loss) and education (dietary and natural history).

z

If glycemic control is unsuccessful with dietary modification, consideration of oral diabetic agents may be considered.

z

Insulin should be used if blood glucose levels do not fall below 120 mg/dL before meals or lesser than 160 mg/dL after meals.

z

Liberal use of endocrinology consultation is recommended for patients with difficult to control diabetes.

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Inflammatory Bowel Disease Conflicting results have been published on the prevalence and severity of IBD after liver transplantation (116,117,118). Differences may be attributed to variation in immunosuppression and/or maintenance IBD medications, duration of IBD, and length of follow-up. Papatheoddoridis et al. reported an aggressive natural history in those not treated with steroids after transplantation (119). Conversely, others have noted mild symptoms and few flares of disease (116,117). Haagsma et al. in a single-center study, reported that 36% of patients with pre-OLT IBD experienced exacerbations at a median of 1 year after transplantation (120). Additionally, 11% of patients developed de novo IBD, with risks of 4% (3 years), 11% (5 years), and 14% (10 years) after transplantation. Interestingly, none of the patients was continued on IBD medications such as aminosalicylates. Most transplantation centers now continue specific IBD medications along with immunosuppressants. A unique feature of this study was that the IBD-free survival was increased in patients not receiving tacrolimus immunosuppression and in those receiving azathioprine. From a different perspective, Dvorchick from Pittsburgh analyzed 303 patients to look at the risk of colectomy after transplantation (121). Twenty-two patients (7%) had colectomy due to refractory disease in follow-up to 12 years post-transplantation. Surprisingly, only OLT was the significant risk factor for colectomy (HR 3.1). Patients with PSC and IBD may have an increased risk of developing colorectal cancer after liver transplantation (122,123). Prior studies have shown the cumulative risk to be between 9% and 14%. Vera et al. from Birmingham, England studied 82 patients with PSC and IBD to identify risk factors for colorectal cancer (124). Colorectal cancer developed in 9.6% of these patients with a mean interval of 46 months (21 to 68 months) between liver transplantation and cancer onset. The cumulative risk of developing colorectal cancer was 14% and 17% after 5 and 10 years after transplantation. Multivariate analysis identified three variables significantly related to colorectal cancer–dysplasia post-transplantation, duration of colitis more than 10 years, and pancolitis. When all three variables were present the risk of colorectal cancer was 100% by 5 years post-transplantation. Recommendations

z

Maintenance use of IBD medications after transplantation (i.e., aminosalicylates).

z

Yearly colonoscopy with surveillance biopsies in patients who underwent transplantation for PSC.

z

If dysplasia is found, colectomy is warranted.

Pregnancy Recovery of normal menstrual function occurs rapidly (within 1 to 2 months of transplantation) in women (125). Unintended pregnancy can occur, therefore contraception should be a topic discussed immediately after transplantation. The most frequent contraceptive practices noted in a questionnaire were barrier methods and tubal ligation (126). In addition, 70% of sexually active patients indicated satisfaction with their relationship, and 75% had weekly intercourse. Pregnancy outcomes after liver transplantation have been reported from single centers to national transplantation registries (127,128,129). All reports demonstrate favorable maternal and neonatal outcomes, with low incidence of congenital malformations. The two most recent reports support the results of prior studies (128,129). The mean birth weights were lower than normal P.1499 (approximately 50%), at a mean gestational age of 36 weeks with around 50% delivered by cesarean section. The Mount Sinai study noted higher pregnancy complications of diabetes mellitus (37%), anemia (33%), elevated creatinine greater than 1.3 mg/dL (25%), preeclampsia (21%), and hypertension (21%). Elevated liver enzymes, graft loss (2%), and rejection were uncommon in the Pittsburgh study, but the Mount Sinai report describes that 10% of patients had spontaneous first-trimester abortions and 26% had terminations of

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pregnancy due to elevated liver function that was thought related to graft rejection. This was more common in patients in whom the etiologies of liver disease were autoimmune hepatitis (4/8) and PBC (2/3).

Table 56.3. Pregnancy Categories for Transplantation Medications

Category B (no evidence of risk) Prednisone Category C (risks cannot be ruled out) Cyclosporine Tacrolimus Mycophenolate mofetil Rapamycin Lamivudine Ganciclovir Interferon Category D (evidence of risk) Azathioprine Category X (contraindicated) Ribavirin

Common transplantation medications carry pregnancy categories of B to X. (Table 56.3) Recommendations

z

Counsel regarding contraceptive practice immediately after transplantation.

z

The National Transplantation Pregnancy Registry advises female liver transplant recipients to wait for more than 1 year to become pregnant.

z

Pregnancy management should include an obstetrician skilled in high-risk pregnancy and the multidiscipline transplantation team.

Transplantation-Related Complications Biliary Complications After OLT, biliary complications occur in 7% to 50% as described in earlier studies (130,131,132,133,134,135). Previously, biliary complications usually required surgical revision; however, endoscopic or interventional radiologic treatment is now the standard of care. Two recognized categories of biliary complications are strictures (anastomotic and nonanastomotic) and leaks (T-tube or anastomotic). In addition, stricture or leaks can be classified as early (90% in the United States) organ procurement is from the cadaveric donor in whom brain death has been confirmed and documented according to requirements of the individual state's laws. The donor dissection is performed during normal perfusion of the organs and before the heart has stopped. This allows for careful dissection of the vasculature of each abdominal organ while pulses are palpable. Normally, the aorta and inferior vena cava are completely dissected from the overlying peritoneum, lymph nodes and soft tissues, in order to identify the renal vein and superior mesenteric artery (SMA). The distal aorta is ligated and a very large bore catheter is inserted into the aorta in a retrograde fashion. Next the supraceliac aorta is isolated just below the diaphragm. An additional catheter is sometimes placed (if size permits) into the inferior mesenteric vein for direct portal venous flush. Further dissection of the hepatic hilum is performed to carefully divide the common bile duct, and isolate the hepatic artery and portal vein. The gastroduodenal artery is usually ligated at this point, which assists in tracing the common hepatic artery proximal to the level of the splenic artery. Next the inferior vena cava is isolated above and below the liver. When the dissection is complete, the cold preservation solution (either University of Wisconsin or histidine-tryptophan-ketoglutarate [HTK] solution) is flushed through the distal aortic catheter. A clamp is placed at the level of the diaphragm to stop the flow of solution from entering the thoracic organs while perfusing all of the abdominal organs. Finally, the vena cava is divided just above the diaphragm to allow blood and the preservation solution to exit the organs. Some surgeons place slush on the abdominal organs during the flushing in order to assist rapid cooling of the organs. The liver (often en bloc with the pancreas and/or intestine) is removed first by dividing the vena cava above and below the liver, and the aorta above the celiac axis and below the SMA. Usually in a slush filled basin with preservation solution, these organs are separated by dividing the portal vein, splenic artery and aorta between the celiac axis and SMA, taking care to identify any replaced right hepatic arteries that might arise from the SMA. This can be somewhat difficult when excessive soft tissue is present in the donor, which obscures these planes.

Donor after Cardiac Death Although the earliest cases of human transplantation were performed with organs procured from donors whose hearts had stopped prior to organ procurement, this practice was largely abandoned after the acceptance of brain death criteria. However, in recent years with the increased need for cadaveric organ donors, attempts to increase the number of available organs has led to the increased use of donors who do not meet brain death criteria. Specific protocols have been established to ensure that the patient is pronounced dead (i.e., lack of cardiorespiratory activity for a specified period of time) by physicians who are not involved with the procurement of the donor organs in order to protect the public from potential abuses. There is an increased risk fof ischemic injury to these organs and only young donors are usually accepted. For the liver allograft, there is an increased risk for both primary nonfunction, which is rare, and for biliary stricture formation, which is more common. In 1998 donor after cardiac death (DCD) donors accounted for 0.7% of the deceased liver donors in the United States. In 2003 this figure has increased to 2.8% and is expected to continue to increase over the next few years (http://www.unos.org) From a technical perspective, in cases where the procurement occurs after the donor's heart beat has stopped, that is, from a DCD donor, skin incision and isolation of vasculature is done rapidly in order to quickly flush with preservation solution (either University of Wisconsin or HTK solution) and rapidly cool the organs. The dissection in DCD donors is then done after cooling the organs and when no blood is flowing through the grafts. Although DCD donors may experience a higher degree of warm ischemia, which can lead to graft injury, the technical aspects of the procedure do not differ other than the speed and order as described in the preceding text.

Liver Transplantation—Recipient Procedure

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The removal of the native liver at the time of liver transplantation is usually the most challenging part of the procedure and arguably one of the most difficult operations performed by surgeons. The development of portal hypertension and vascularized adhesions places the recipient at high risk for rapid and excessive blood loss. A successful transplantion team not only requires a gifted surgeon, but also requires an experienced team of anesthetists to manage the blood loss and electrolyte shifts intraoperatively. The recipient hepatectomy is achieved by ligating and dividing the native bile duct, the proper hepatic artery or it's individual branches, clamping and dividing the portal vein high in the hilum and dividing the inferior vena cava above and below the liver. Figure 57.1 shows the abdominal cavity after the native hepatectomy. The whole liver allograft is then taken out of the cold preservation solution. The anastomosis of the donor suprahepatic inferior vena cava is made end to end to the native inferior vena cava at the level of the P.1513 native hepatic veins. The infrahepatic vena caval anastomosis is likewise performed end-toend above the native renal veins in the recipient. The portal venous anastomosis is then performed end-toend and often the graft is revascularized at this point to minimize the length of warm ischemia. Next the hepatic artery is reconstructed to the native hepatic artery, the gallbladder is then removed and the bile duct is anastomosed to the native bile duct, often over a T-tube. Figure 57.2 shows these attachments in the recipient. There are technical variants to this standard approach such as the piggy-back technique, the use of interposition grafts or the use of the inferior vena cava for portal venous inflow in cases of portal vein thrombosis that are beyond the scope of this chapter.

▪ Figure 57.1 Abdominal cavity after native hepatectomy.

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▪ Figure 57.2 The recipient's abdomen showing the anastomoses required in the liver transplant procedure.

Alternatives to Standard Cadaveric Liver Transplantation—Historical Perspective In response to the increasing risk of death for patients awaiting liver transplantation, alternatives to whole organ cadaveric grafts (such as the use of DCD donors described in the preceding text) have been sought. The most commonly used clinical alternative to whole cadaveric liver transplantation has been partial liver transplantation, which includes reduced-size, split-liver and living related transplantations.

Reduced-Size Liver Transplantation The technique of reduced-size liver transplantation (RSLT) is presented primarily for historic purposes. Although this technique increased the number of livers available for transplantation in children, it had the undesired effect of reducing the pool of cadaveric organs available for adult recipients, who represented more than 90% of the patients on the waiting list. It has therefore been all but abandoned for the alternative of split-liver transplantation described in the subsequent text. RSLT implies the use of a portion of the donor liver and was the first form of partial liver transplantation introduced. The technique of reduction of the liver allows livers from larger donors to be used in smaller recipients, who traditionally had higher rates of mortality on the waiting list (1). It was introduced clinically in 1981 and Bismuth first reported the successful transplantation of a reduced-size liver graft in 1984 (2). The technique was primarily used for the smallest children awaiting transplantation and at one time accounted for as many as 75% of transplants performed on children weighing less than 10 kg (3). The main goal of RSLT was to decrease pretransplant mortality and this was achieved. With this experience it became apparent that these reduced-size livers functioned well and not good as full-sized organs with comparable rates of postoperative complications. The successful application of RSLT directed efforts to divide the liver in such a way that not only the pediatric recipient could receive a transplant, but that the larger right side of the liver could be transplanted into another recipient, often a larger child or adult. This technique came to be known as split-liver transplantation.

Split-Liver Transplantation Split-liver transplantation is an attractive concept that provides transplants for two recipients from a single cadaveric liver. Typically, the left lateral segment is P.1514

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transplanted in a child and the right lobe in an adult (or larger child). The first reported split-liver transplantation was performed by Pichlmayr et al. in 1988 who transplanted the right lobe into an adult with primary biliary cirrhosis, and the left lateral segment into a child with biliary atresia (4). Subsequently, Bismuth et al. reported using the technique to transplant in two patients with fulminant hepatic failure (2). These results were discouraging due to technical complications and poor recipient selection. However, perseverance by a few centers has proved that standard application of split-liver transplantation can increase the number of available liver grafts from cadaveric donors as much as 26% to 28% (5,6). Generally, only optimal cadaveric donors are considered candidates for splitting because of the potential for increased preservation injury, especially if the splitting occurs ex vivo. Estimates based on usual donor characteristics in the United States reveal that between 15% and 25% of cadaveric donors may be suitable for splitting (7).

Ex vivo technique The technique of ex vivo split begins with a standard whole organ procurement and its packaging in preservation solution. After the graft is transported to the recipient transplantion center, the graft is divided on the back table. The hilar structures (hepatic artery, portal vein and bile duct) are dissected and divided between the two hemi-livers. Cholangiography and/or arteriography to delineate anatomy are performed as needed (5,8). There are varying opinions as to how the vessels should be divided. The key to successful splitting of the liver is to share vascular and biliary structures between the two grafts without compromising either side and preferably providing each graft with a single firstorder arterial and biliary structure. Some centers routinely retain the full length of the hepatic artery and portal vein with the left hemi-liver and other centers routinely retain the full length of the vessels with the right hemi-liver. Most centers retain the vena cava with the right lobe graft. Because the left biliary anatomy is more consistent, the left bile duct, which is generally a single duct, is usually divided above the hepatic bifurcation, and the common hepatic duct is retained with the right lobe graft. The parenchymal transection is performed either with the mosquito fracture technique or by sharp dissection. The line of transection extends from the confluence of the left and middle hepatic veins (MHVs) to the right side of the falciform ligament and umbilical fissure down to the hilar plate (Figure 57.3) (9,10). In most centers, Couinaud segments I and IV are resected and discarded, to avoid acute necrosis or less common gradual atrophy (9,11).

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▪ Figure 57.3 Lines of transection for the different split-liver allografts.

P.1515 Recently, full-left full-right splitting for two adult recipients has been reported by Colledan et al. This technique leaves a right lobe graft comprising Couinaud segments V—VIII, and a left lobe graft consisting of segments I–IV. The vena cava and MHV are retained with the left lobe graft (12). Early experience suggested that using this technique put the right lobe graft at risk for congestion of the anterior sector (segments V–VIII) and that the recipients of the left lobe grafts may develop inferior outcomes due to small-for-size syndrome. Solutions to these problems include preserving the MHV with the right lobe graft or reconstructing the segment V and VIII veins. Preserving the MHV is a less attractive option as this further reduces the size of an already small left lobe graft. A recent report by Broering et al. describes a novel technique of splitting the MHV between the left and right lobe grafts and using a split iliac vein conduit as a patch venoplasty (Figures 57.4A and 57.4B). This technique in conjunction with their previous description of splitting the vena cava between both grafts creates a common venous outflow for the whole left or right lobe graft. This technique can be performed only by ex situ splitting, but appears to provide improved outcome compared to prior reports of splitting cadaveric livers for two adult recipients (13).

In situ technique The in situ split technique is essentially the same as the living liver donor technique further discussed in the subsequent text. Rogiers et al. reported the first case of split-liver transplantation with the in situ technique in 1995 and a series of 14 split grafts in 1996 (14,15). A left lateral segmentectomy was completed in the heart beating cadaveric donor and flushed on the back table with preservation solution. This was followed by standard multiorgan procurement of the remainder of the intra-abdominal organs with in situ flushing of University of Wisconsin solution as described in the preceding text. Hepatic segments I and IV could therefore be evaluated in the donor prior to the flushing to assess perfusion after ligation of the left sided vessels, and excised only if the appearance suggested that they were compromised (14). Busuttil et al. in his series likewise performed the hepatic transection without vascular interruption, however he flushed both the hepatic segments in situ prior to removal from the cadaveric donor (7).

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▪ Figure 57.4 Proposed method for division of the middle hepatic vein for split-liver graft for two adults.

The implantation of the split allograft is independent of the method of procurement (ex vivo or in situ). Generally, the right split graft retains the donor retrohepatic inferior vena cava and is therefore transplanted in the standard orthotopic technique described for whole organ grafts. The left split graft is generally implanted in the so-called piggyback technique to the confluence of the native middle and left hepatic veins (see Figure 57.5). Extension grafts of donor iliac vessels may be used with either the left or right split graft for the hepatic artery or portal vein as needed. Bile drainage is frequently performed by formation of a hepaticojejunostomy, however choledochostomy has also been reported (14).

Results Until recently, the patient and graft survival rates for recipients of split-liver grafts (50%– 67% and 43%–50%, respectively) were lower than the rates for whole organ grafts (6,16,17). The decrease in patient and graft survival was most pronounced for the recipients of the right lobe. The diminished survival was probably a result of poor recipient selection combined with prolonged cold ischemia, and warming of the graft during the ex vivo preparation (7). By restricting split-liver transplantation to elective situations, the results have improved and are now comparable to whole organ grafts even for the right lobe graft (5,18). Reports of in situ splitting have revealed that this technique can be used even in urgent recipients without compromising patient and graft survival (7).

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▪ Figure 57.5 Technique for graft implantation using “piggyback technique” for the left lateral segment performed in both cadaveric and living donors.

P.1516

Complications of split graft transplantation Transplantation with a split graft was initially associated with increased bleeding. In the early series as many as one-third of ex vivo split-liver graft recipients required reoperation or transfusion for early postoperative bleeding (6). In contrast, after in situ split-liver grafting, bleeding occurred in less than 3% of recipients (7,14). Ex vivo splitting is also associated with a higher risk of biliary complications (22%–27%) compared to whole organ (4%)or in situ split grafts (0%–3%) (5,6,7,14,18). Rates of arterial thrombosis and primary graft nonfunction in recent series are similar regardless of graft source (7,9,14). Split-liver grafts more efficiently use cadaveric donors than RSLT because the total number of livers available for transplantation is doubled. Furthermore, with split-liver grafts the redistribution of adult cadaveric livers to pediatric recipients created with reduced-size grafts is avoided (19). Despite the recent publication of splitting for two adult recipients, split-liver transplantation is currently used primarily to provide a left lateral segment graft for a pediatric recipient with an adult recipient receiving the extended right lobe graft. Unfortunately, the most attractive potential application of the technique (i.e., splitting a liver for two adult recipients) has not been generally achieved. There are a variety of reasons for this failure to apply split-liver transplantation for two adults in the United States. One of the most important considerations, however is that the full left lobe of the liver provides inadequate functional hepatic mass for most adult recipients in the United States because of the relative obesity of the population. The acceptable range of hepatic mass required to achieve successful hepatic function after liver transplantation is further discussed in subsequent text. As clinical experience with liver resections and partial liver grafts from cadaveric donors increased, it appeared feasible to safely use living donors for partial liver transplantation.

Living Donor Liver Transplantation The introduction of live donors for liver transplantation (LDLT) was delayed compared to kidney transplantation. Although LDLT has been practised since the 1960s, and according to UNOS in 2004 accounted for 41% of all kidney transplants performed, LDLT was first introduced in 1989 for pediatric recipients (http://www.unos.org) (20,21). The right lobe

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LDLT for adult recipients was introduced much later in 1998 (22). The main impediments to broader application of LDLT to larger recipients were twofold. First, surgeons were concerned with donor safety associated with larger hepatic resections and secondly, they were concerned about providing adequate hepatic mass for the recipient. Owing to the resection of up to 75% of the hepatic parenchyma during a right lobe resection, the risks for complications in the donor are much higher than in left lateral segment liver resection or removal of a kidney. The focus of this section will be a review of world experience with LDLT for adult recipients.

Graft size considerations Two methods for determining whether a graft will have adequate functional hepatic mass have been developed. The first method involves the calculation of the graft to recipient weight ratio (GRWR) which compares the mass of the graft to the overall body mass of the recipient (23). The second method involves the calculation of the liver volume as a percentage of the standard liver volume (SLV) (% SLV) using a mathematical formula based on measurements of the liver at autopsy (24). Table 57.1 shows examples of both of these calculations. A recent review shows that there is a nearly perfect (i.e., linear) correlation between these two estimates of liver volume, and both the methods can therefore be used interchangeably (23).

Early experience with living donor transplantation in adult recipients The earliest experience with transplantation of adults using living donors merely extended the pediatric experience using either the left lateral segment or full-left lobe grafts (with or without the MHV) (26,27,28). The size of partial left liver grafts, however, in most cases P.1517 corresponds to only 20% to 35% of the recipient's expected SLV (Table 57.1). Although successful graft function has occurred with grafts as small as 0.6% GRWR (25% SLV) (29), others have reported increased risk for postoperative morbidity and mortality with the use of grafts less than 1.0% GRWR (50% SLV) (23,24,30). Grafts less than 0.8% to 1.0% GRWR or “small-for-size grafts” generally demonstrate poor graft function marked by pronounced cholestasis and prolonged coagulopathy (30). The use of left lobe grafts in adult recipients is therefore limited to recipients with body weight in the range of 45 to 55 kg. In the United States, one would expect this weight restriction to represent only a minority of individuals on the waiting list. Indeed, at the University of Nebraska Medical Center this represents only 11% of the adult waiting list. The right lobe of the liver on the other hand represents approximately 60% of the hepatic parenchyma and for most adults in the United States would provide at least 1% GRWR. The Kyoto group performed the first right lobe liver transplant in a child in 1994; however because of concerns about donor safety right lobe living donor liver transplants were not offered to adult recipients until 1997 and 1998 (22,31,32). Since 1998 right lobe liver grafts from living donors have become the standard graft for adult recipients (32,33,34).

Table 57.1. Methods of Evaluating Adequacy of Partial Liver Graft for a Recipient

GRAFT-TO-RECIPIENT WEIGHT RATIO

Example. Recipient body weight = 70 kg

Graft weight = 700 g

GRWR = 700 g ÷ 70 kg = 0.01 (or 1%)

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Optimal GRWR = 1%–3%

CALCULATION OF STANDARD LIVER VOLUME a (SLV) (24)

Japanese formula for SLV (mL) = 706.2 × (body surface area [m 2 ]) + 2.4

Example. In a 5 ft. 8 in. 75 kg recipient BSA is approximately 1.88 m 2

SLV = 1.33 L (or approximately 1330 g using above formula)

If donor right lobe estimate on computed tomography scan measures 700 g, then 700/1330 = 53% SLV

Optimal % SLV = >50%

SLV, standard liver volume; BSA, body surface area. a Since North European and American whites generally larger than Japanese individuals, revised formula in the subsequent text may be more accurate in these populations (25). Heinemann formula (25) for SLV (ml) in whites = 1072.8 × (body surface area [m2])—345.7 a

Donor Selection There are two key issues in donor selection. First, living liver donation should be voluntary without coercion and without financial incentives. Secondly, the potential donor should have minor and well-controlled or no medical conditions in order to avoid increased risk from the donor operation. Most living donors have been immediate family members and rarely close friends (34,35). Caution must be exercised in the evaluation process however, because family members may intentionally or unintentionally place pressure on relatives of appropriate age and blood type to donate. The evaluation process includes an interview with the potential donor in the absence of other family members and is ideally performed by a physician who is not a member of the transplant team. The potential donor is informed of the option for the transplant team to provide a “medical excuse” at any time if he/she chooses not to donate. Minors are generally excluded from living donation. Some have raised concerns over the issue of informed consent with the small experience that currently exists (36). The American Society of Transplant Surgeons (ASTS) position paper presented at the May 2000 meeting concurs that insufficient information currently exists “to accurately assign risk for the donor” and this should be acknowledged to the potential donor during the evaluation. The evaluation process of the potential donor includes determination of blood type and confirmation that this is compatible with the recipient's blood type. Other commonly performed laboratory tests include liver and kidney function tests and viral serologies. Most donors in published series are between 24 and 61 years old. Age is not an absolute contraindication to living donation, however older individuals have a higher likelihood of silent cardiac or cerebrovascular disease that may increase the perioperative risk and the liver may have a decreased potential for regeneration in the older donor. Computed tomography (CT) angiography or magnetic resonance (MR) angiography with three-dimensional reconstruction are the current imaging modalities used to delineate hepatic vascular and biliary anatomy and to determine the potential graft and whole liver volume. Magnetic resonance cholangiopancreatography (MRCP) is usually performed when MR angiography is done but intraoperative cholangiography is P.1518

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usually performed in addition to further delineate biliary anatomy.

Donor Safety Since the highly publicized donor death in New York, donor safety has become the overriding concern with respect to LDLT. A recent survey by Brown et al. of 449 living donors in the United States documented the actual risk of death to be 0.2% (37). To date however there have been three reported deaths in the United States of America, four in Europe and one each in Japan, India, Egypt and South America (37,38). Interestingly, many of the largest centers in the United States have been the slowest to adopt this technique primarily due to concerns over donor safety. The National Institutes of Health (NIH), the ASTS and the US Department of Health and Human Services have organized a multicenter study to gather and follow sufficient numbers of patients undergoing right lobe LDLT in the United States of America, which will hopefully guide future application of this valuable technique.

Technique for Procurement of the Living Donor Right Lobe Graft The right liver graft consists of segments V-VIII with or without inclusion of the MHV. There is much debate over the provision of adequate drainage of the anterior sector of the graft and inclusion of the MHV. The donor liver procurement of the right lobe graft begins with a bilateral subcostal incision and division of the hepatic ligaments to the right hepatic lobe. The ligamentous attachments of the left lobe remain intact to prevent torsion of the remnant liver after right lobectomy. The liver is then mobilized off the retrohepatic vena cava carefully ligating small accessory hepatic veins. Marcos et al. recommends preservation of any accessory hepatic vein greater than 5 mm in diameter for reimplantation (33). Intraoperative ultrasound is then used to identify the intrahepatic course of the right and MHVs to determine the optimal line of transection. Hilar dissection is performed to identify the branches to the right lobe from the hepatic artery and portal vein. Minimal if any dissection is performed of the right hepatic duct(s) and left hilar structures. Cholecystectomy and cholangiography are then performed to assess biliary anatomy. The right hepatic vein (RHV) is also isolated prior to parenchymal transection if possible and controlled with a vessel loop. At the University of Nebraska Medical Center the Cavitron ultrasound surgical aspirator (CUSA) ultrasonic dissection is used to transect the hepatic parenchyma. Although this is a somewhat tedious process, it allows identification and ligation of large portal and hepatic venous branches that cross the plane of transection thereby minimizing blood loss. No inflow or outflow vascular occlusion is performed during the process of hepatic parenchymal transection in order to minimize ischemic injury to either portion of the liver. Figure 57.6 shows the right lobe graft after parenchymal transection and division of the hepatic artery, portal vein, right hepatic duct and RHV. Figure 57.7 demonstrates the method of implantation of this P.1519 right hepatic lobe graft. This differs from the technique of reduced-size or split-liver right lobe grafts because of the absence of the donor inferior vena cava. In the recipient of the living donor right lobe graft the native inferior vena cava is preserved and the donor RHV is anastomosed directly to the recipient RHV orifice in the so-called “piggy back technique”. Extension vascular grafts are rarely required with the right lobe graft. Biliary drainage is most commonly performed by Roux-en-Y hepaticojejunostomy although duct-to duct anastomosis has also been reported (22).

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▪ Figure 57.6 Technique of living donor right lobe graft including the middle hepatic vein and demonstrating division of the right portal vein, hepatic artery and right lobe bile duct.

▪ Figure 57.7 Implantation of the right lobe graft.

Ongoing Controversies The two main controversies with regard to right lobe LDLT that warrant further discussion are the venous drainage of the anterior sector of the right lobe graft and the preferred

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mode of biliary reconstruction.

Hepatic Venous Drainage Although graft size is now well documented enough to be a critical factor in the success of partial liver grafts, the importance of good venous drainage in order to prevent congestion particularly of the anterior sector of the graft and the development of small-for-size syndrome (prolonged cholestasis, coagulopathy and ascites) has been more recently recognized (39). Different approaches have been adopted to prevent congestion from occurring, ranging from reconstruction of segment V and VIII veins to routine inclusion of the MHV with the graft (40). Although Lo et al. routinely include the MHV, the overriding concern with this practice is that the remnant native liver may be decreased excessively in size or have poor venous drainage leading to greater risks for complications in the donor. Lee et al. reported on five right lobe living donor transplants without drainage of segment V and VIII veins or inclusion of the MHV. They found congestion followed by ascites, cholestasis and sepsis in two of the five, with one of the patients dying twenty days after transplant (41). Subsequently the same authors reported reconstruction of the segment V and VIII veins using interposition vein grafts of either iliac vein or saphenous vein and now recommend this in all cases (42). The Tokyo group proposed a selective approach to drainage of the segment V and VIII veins based on the results of two intraoperative tests during the donor operation (43). (1. After MHV clamping, Doppler flow in the portal vein is assessed. Reversal of flow indicated the need for drainage of the anterior sector veins. 2. After clamping the MHV and the right hepatic artery, if the anterior segment became dusky, drainage was required.) Cryopreserved or autologous vein grafts were used to provide this drainage as needed. Of thirty right lobe living donor transplants performed, 18 required reconstruction based on these tests (42). The Hong Kong group as noted in the preceding text recommends routine inclusion of the MHV with the right lobe graft in order to avoid congestion of the graft (40,44). They have reported a 96% graft survival at 2 years using this technique. De Villa et al. proposed a selective approach to inclusion of the MHVs only when the right lobe graft volume estimate is Table of Contents > Volume 2 > Section XII - Elements of Liver Transplantation > Chapter 58 Recurrent Disease Following Liver Transplantation

Chapter 58 Recurrent Disease Following Liver Transplantation Hugo R. Rosen James R. Burton Jr.

Key Concepts z

Recurrent liver disease can occur for virtually all indications of liver transplantation.

z

Hepatitis C virus (HCV) recurrence defined by histologic injury is almost universal and a significant proportion (20% to 30%) develops allograft cirrhosis by the fifth year post-transplant.

z

HCV-related allograft cirrhosis is associated with a high rate of decompensation and mortality.

z

The natural history of hepatitis B virus recurrence has been dramatically modified and outcome substantially improved by use of human immune globulin and nucleoside analogs.

z

Recurrent autoimmune liver diseases (primary biliary cirrhosis, primary sclerosing cholangitis, and autoimmune hepatitis) appear to have excellent intermediate patient and graft survival rates.

z

The diagnosis of recurrent autoimmune liver diseases requires careful exclusion of alternative diagnoses (e.g., rejection, biliary obstruction) that can mimic the recurrent disease.

z

Although recurrent alcohol use after transplantation for alcoholic liver disease is common, direct or indirect negative effects of recurrent alcohol use on the allograft is rarely seen.

z

Recurrent Budd-Chiari syndrome can occur days to years after transplantation.

Liver transplantation is a well-established standard of care for many patients with end-stage chronic liver disease and acute liver failure. Despite excellent long-term survival, disease recurrence after liver transplantation is a relatively common problem. The clinical significance of this recurrence varies widely depending on the primary indication for liver transplantation. This chapter will primarily focus on disease recurrence after liver transplantation for viral hepatitis and autoimmune liver diseases with emphasis on natural history, risk factors for recurrence, diagnosis and management (Table 58.1). Significant attention will be paid to recurrent hepatitis C virus (HCV) infection, because currently HCV is the leading indication for transplantation and unlike other indications for liver transplantation, it is not a question of whether recurrence will happen, but how it will affect outcome and how best to manage or prevent recurrent viral hepatitis. Discussion on hepatitis B virus (HBV) will focus on the historical evolution of treatment with hepatitis B immune globulin, and more recently, the use of nucleoside analogs in preventing and managing disease recurrence. Clinically significant recurrent autoimmune liver diseases appear to be relatively rare; furthermore, study of this problem is limited by variable study design, small patient numbers, different immunosuppressive regimens, lack of long-term follow-up and established criteria and markers for diagnosing disease recurrence. Brief discussion will include recurrent alcoholic liver disease (ALD), a major contributor to the

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development of end-stage liver disease in the United States, as well as to Budd-Chiari Syndrome (BCS). Recurrent hepatocellular carcinoma and cholangiocarcinoma are discussed in Chapters 44 and 45, respectively. In addition, the important issue of retransplantation for recurrent disease is discussed in detail in Chapter 59.

Table 58.1. Recurrent Diseases

Incidence Cholangiogram

of Category

recurrence

Diagnosis

Biopsy findings

findings

VIRAL HEPATITIS

Hepatitis C

Viremia

HCV RNA by PCR

Periportal

Normal

A

universal;

inflammation,

re

60%–80%

lobular

H

acute

hepatitis

in

hepatitis at

h

4–6 mo,

th

chronic

a

hepatitis

h

80%–100% at 1–4 y

Hepatitis B

Historically,

HBsAg (often

Periportal

without

HBeAg-positive

inflammation,

Normal

A re

HBIG,

with high HBV

lobular

H

50%–85%;

DNA levels)

hepatitis

in

risk 90

h

with/without

d and

th

ductopenia,

diverticulum-like

n

biliary fibrosis

outpouchings

s

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or biliary

d

cirrhosis

in C p is

Autoimmune

20%–30%

hepatitis

Biopsy, positive

Periportal

autoantibodies,

hepatitis,

Normal

re

and exclude

lobular

h

alternative

inflammation

(

diagnoses

A

h th b o

HCV, hepatitis C virus; RNA, ribonucleic acid; PCR, polymerase chain reaction; Peg-IFN, pegylat hepatitis B e antigen; DNA, deoxyribonucleic acid; GVHD, graft versus host disease; UDCA, urso Cytomegalovirus; HLA, human leukocyte antigen; LT, liver transplantation; AIH, autoimmune he

P.1526 P.1527 P.1528

Recurrent Viral Hepatitis Hepatitis C Virus HCV-related end-stage liver disease is the most common indication for liver transplantation in the Western world. Recurrence of HCV infection after liver transplantation is nearly universal based on the presence of HCV ribonucleic acid (RNA) in the serum. During the anhepatic period HCV RNA levels typically decline to low and sometimes even undetectable levels (1,2). Four to 8 days after transplantation, viral levels often increase to levels 20fold greater than in the pretransplant period (3), typically peaking between 1 and 3 months post-transplantation. Evidence of histologic damage may occur in the non–HCV-infected recipient because of several causes including recurrent disease, however, abnormal liver biopsies are significantly higher in HCV-infected recipient than among controls (70% vs. 15% at 1 year post-transplantation; P < 0.0001) (4). Acute hepatitis occurs in 60% to 80% at a median of 4 to 6 months after transplantation and chronic hepatitis in 80% to 100% by 1 to 4 years (5,6,7). Acute recurrent HCV infection often causes increasing serum aminotransferases. Typically, liver biopsy is performed at this time to exclude acute cellular rejection (ACR), although uniform practice in this respect between transplant centers does not exist. Empiric treatment of ACR is not recommended as both ACR and recurrent HCV can improve with steroid boluses and steroid boluses have been shown to promote fibrosis progression in recurrent HCV (8,9). ACR often occurs within the changes of recurrent HCV; therefore often the distinction is not between recurrent HCV infection and ACR, but rather between ACR with or without underlying features of recurrent HCV infection. Table 58.2 outlines the histologic features of recurrent HCV and ACR (10,11). Following this acute HCV recurrence, chronic recurrent HCV develops, demonstrated by chronic hepatitis with variable degrees of mixed portal, periportal, and lobular inflammation with or without viable degrees of portal and/or periportal fibrosis. The severity of recurrent HCV should be defined by grade (necroinflammation) and stage (fibrosis).

Table 58.2. Histologic Features of Recurrent Hepatitis C Virus Versus Acute

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Cellular Rejection

Recurrent hepatitis C virus (HCV)

Acute cellular rejection

Time post–liver

Anytime; usually within the

transplantation

first year

Usually in first 2 mo

Portal

Most cases; mononuclear

Inflammation

infiltrate

Aggregates

Usually

Occasionally

Follicles

50% of cases

Very rarely

Eosinophils

Inconspicuous

Almost always

Steatosis

Often

Never

Acidophilic

Common

Uncommon

Duct damage

Approximately 50% of cases

Very common

Other

Bridging necrosis or fibrosis

Endotheliitis and central

Always; mixed infiltrate

bodies

venulitis

Atypical features

Cholestasis, ballooning

Prominent periportal and

degeneration without

lobular necroinflammatory

significant inflammation,

activity without

marked ductular proliferation

subendothelial venular

mimicking obstruction,

inflammation

granuloma

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▪ Figure 58.1 Probability of developing decompensated cirrhosis (ascites, encephalopathy, or variceal hemorrhage) from the time of diagnosis of hepatitis C virus (HCV) cirrhosis (pretransplant) and HCV allograft cirrhosis (post-transplant). (Adapted with permission from Berenguer M, Prieto M, Rayon JM, et al. Natural history of clinically compensated HCV-related graft cirrhosis following liver transplantation. Hepatology 2000;32:852–858; and Fattovich G, Giustina G, Degos F, et al. Morbidity and mortality in compensated cirrhosis type C: a retrospective follow-up study of 384 patients. Gastroenterology 1997;112:463–472.)

▪ Figure 58.2 Survival rates for compensated and decompensated hepatitis C virus (HCV) cirrhosis and HCV allograft cirrhosis. (Adapted with permission from Berenguer M, Prieto M, Rayon JM, et al. Natural history of clinically compensated HCV-related graft cirrhosis following liver transplantation. Hepatology 2000;32:852–858; and Fattovich G, Giustina G, Degos F, et al. Morbidity and mortality in compensated cirrhosis type C: a retrospective follow-up study of 384 patients. Gastroenterology 1997;112:463–472.)

The natural history of chronic HCV is highly variable and poorly understood. For some, the natural history is accelerated compared with the nontransplant setting; 20% to 40% of patients transplanted for HCV develop allograft cirrhosis after only 5 years as compared to 3% to 20% after 20 years in the nontransplant setting (12,13,14,15). Once cirrhosis develops in the transplant setting, two-thirds will develop decompensation within 3 years (Fig. 58.1) (15,16). The development of decompensation is associated with a very poor outcome with P.1529 approximately only 10% surviving 3 years (Fig. 58.2) (15,16). Although nearly all patients develop some evidence of histologic recurrence, approximately a third will develop only minimal fibrosis after 5 years of follow-up (17). Although many studies have shown that short-term patient and graft survival is similar for patients undergoing liver transplantation for HCV compared to other indications, these studies were likely underpowered to detect small differences. Analysis of the United Network for Organ Sharing (UNOS) database revealed significantly diminished survival at 5 years after primary liver transplantation in HCV-positive patients (65.6% vs. 56.7% for HCV-negative transplant recipients; P < 0.05) (18). The presence of rapidly progressive cholestatic HCV is observed in approximately 5% of patients transplanted for HCV, typically developing 1 to 3 months post–liver transplant and resulting in graft failure in 3 to 6 months (19). Characteristics of this syndrome have been outlined by a recent consensus conference (19). Patients typically have very high serum HCV RNA levels with serum bilirubin levels greater than 6g/dL and alkaline phosphatase

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levels greater than five times the upper limit of normal. Patients should not have a history of hepatic artery thrombosis, nor any surgical biliary complications (i.e., normal cholangiogram). Liver biopsy often reveals ballooning of hepatocytes predominantly in the perivenular zone (not necrosis or fallout), paucity of inflammation, and variable degrees of cholangiolar proliferation without bile duct loss. The pathogenesis of this syndrome remains undefined, but preferential Th2 cytokine production by intrahepatic lymphocytes has been implicated (20,21). Optimum treatment remains uncertain, but is focused on reducing very high HCV RNA levels by reducing immunosuppression and indefinite use of interferon (22). A number of factors have been identified that impact both severity of HCV recurrence as well as patient and graft survival. Table 58.3 outlines these viral, recipient, donor and posttransplant factors. The effect of HCV on living donor liver transplantation (LDLT) is controversial. Some studies have suggested earlier and more severe recurrent HCV, including cholestatic HCV, following LDLT compared to deceased donor controls (33,34,35), whereas others have suggested no difference in recurrence or patient or graft survival (36,37). Each P.1530 study has limitations, including small numbers, being from a single center, lack of protocol liver biopsies, and short-term follow-up. Results of the National Institutes of Health (NIH) sponsored multicenter Living Donor Liver Transplant Cohort Study will help clarify these issues. Another controversial issue in terms of HCV recurrence is the suggestion that the rate of fibrosis progression in recent years appears to be accelerating (38). There are many potential factors that could account for this finding including development of new immunosuppressive agents, reduction in overall immunosuppression, more frequent use of interferon therapy prior to liver transplantation, thereby selecting for more virulent HCV strains and use of older and marginal donors in patients with chronic HCV infection.

Table 58.3. Factors Associated with Severe Recurrence and Patient and Graft Survival After Liver Transplantation for Hepatitis C Virus

Viral Pre-LT viral load (23,24)

Early post-LT viral load (28)

Recipient

Donor

Age >60 y (25)

Age >50 y (26,27)

Lack of CD4 +

Warm ischemia

response (29)

time (30)

Pre-LT lack of IFN response (?)

Non-white (24,25)

Steatosis (?)

Post-LT

Female gender (18)

Cold ischemia time (?)

Treatment of rejection with steroids

CMV infection

(8,9)

(27,31)

HLA-matching (?)

Treatment of rejection with anti-

Diabetes (25)

LDLT (?)

Previous HCV

HCV-positive (?)

lymphocyte preps (24,32)

Rapid steroid taper (26)

Treatment (?)

LT, liver transplantation; ?, data either conflicting or unknown; CMV,

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Cytomegalovirus; HLA, human leukocyte antigen; LDLT, living donor liver transplantation; HCV, hepatitis C virus.

The optimum immunosuppressive regimen for HCV-infected liver recipients remains to be defined. The use of high-dose maintenance steroids for prevention of ACR has been associated with decreased patient and graft survival compared to non–HCV-infected transplant patients (24). One consistent finding in the literature is the lack of significant differences in outcome in recipients treated with tacrolimus versus cyclosporine-based immunosuppression. The impact of mycophenolate mofetil on HCV recurrence is unclear and the effect of sirolimus has not been thoroughly studied. Given the accelerated natural history of HCV recurrence, several approaches have been proposed to prevent or slow the progression to HCV-related graft failure. Current treatment strategies fall into three general categories: (i) Pretransplant antiviral therapy, (ii) preemptive therapy (prophylaxis) started in the early post-transplant period before the development of clinically apparent acute hepatitis, and (iii) post-transplant therapy at the time of diagnosis of acute hepatitis or for established and/or severe chronic hepatitis. With viral clearance post-transplant, both long-term absence of HCV RNA in the liver and marked histologic improvement (inflammatory scores much more so than fibrosis scores) have been described (39). Unfortunately, most published studies investigating the role of treating recurrent disease with interferon with or without ribavirin (no longer the standard of care) have been small, single center, uncontrolled trials with significant variability in patient selection and type and timing of antiviral therapy administered, and study endpoints evaluated (i.e., histologic response, end of treatment response [ETR], sustained virological response [SVR]). Rates of SVR are far less than those achieved in immunocompetent HCVinfected patients. Potential reasons for this difference include higher HCV RNA levels post– liver transplant, a high frequency of genotype 1 patients and the clinical status of liver transplant patients, especially in the early post-transplant period, leading to poor tolerability and need for frequent dose reductions. Approximately only 60% of transplant recipients are eligible for preemptive therapy with interferon and ribavirin and the need for dose reductions during therapy are frequent, occurring in 28% to 50% of treated patients (40,41). The major reason for dose reductions is cytopenia, seen both at baseline in many transplant patients and as a direct result of therapy. Use of growth factors to prevent this problem is not uncommon. Another problem in the transplant patient is renal insufficiency, limiting the use of ribavirin on account of its associated risk of hemolytic anemia. The risk of rejection with interferon therapy is controversial. Some studies have not noted an increased risk of rejection with interferon treatment (41,42,43,44), whereas others have described an increased risk (45,46). The exact prevalence and severity is therefore debatable. Whether rejection is more common with pegylated interferon remains to be proven. Pretransplant antiviral therapy for HCV is discussed elsewhere. In terms of HCV-infected patients on the transplant waitlist, these patients are often deemed too ill to consider therapy. However, 93% of infected patients on the waitlist have Model for End-Stage Liver Diseases (MELD) scores of 18 or less (19,47). The arguments to consider therapy in cirrhotics pretransplantation is that clearance or suppression may eliminate risk of developing recurrent HCV and suppression of HCV viral load pretransplant might reduce disease severity post-transplant (48). Successfully treating patients on the waitlist with a

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low, accelerating dosage regimen has been described (49). Of 124 patients with advanced HCV disease (mean MELD = 11.0 ± 3.7; Child-Pugh class B and C was 36% and 19%, respectively), 22% achieved a SVR (13%—genotype 1, 50%—nongenotype 1). Of the 47 patients in this cohort that underwent liver transplantation, 15 had undetectable HCV RNA prior to transplant and 12 remained HCV RNA negative at least 6 months post-transplant. Current consensus recommendations are to strongly consider treatment in patients with MELD scores less than 19 (Child-Turcotte-Pugh [CTP] 80% in patients alive for more than 2 months after liver transplantation was a major factor in 73% of all post–liver transplantation deaths beyond the first 60 days) (63). Once recurrence was established it often followed an aggressive course, progressing from severe chronic hepatitis to cirrhosis and graft failure within 1 to 2 years of reinfection and a 2-year mortality of 50% compared with 20% among patients transplanted for other liver diseases (64). A quarter of patients would develop an aggressive fibrosing cholestatic variant leading to rapid graft failure (64,65). Because of these poor outcomes with transplantation for HBV, many programs considered HBV infection (especially with viral replication) a relative contraindication to transplantation in the early 1990s. A landmark multicenter European study of 334 liver transplant recipients with HBV helped identify three key determinants of HBV recurrence after liver transplantation: (i) Presence of HBV replication, (ii) type of HBV-related liver disease, and (iii) presence of passive immune prophylaxis using HBIG (66). Three-year actuarial risk of HBsAg recurrence among patients with HBV-related cirrhosis was 83% in patients seropositive for HBV deoxyribonucleic acid (DNA) at the time of transplant, 66% among those seronegative for HBV DNA and seropositive for HBeAg and 58% in those seronegative for both HBV DNA and HBeAg (P < 0.05). Three-year actuarial risk of recurrence was significantly higher among patients undergoing liver transplantation for HBV-related cirrhosis (67%) than among those undergoing transplantation for hepatitis delta virus–related cirrhosis (32%) or fulminant HBV (17%) (P < 0.001). Risk of recurrence was significantly reduced with long-term use of HBIG (>6 months) as compared to no immunoprophylaxis and short-term use ($100,000 and subsequent yearly charges of >$50,000) (81). Although previously associated with many potential side effects (immune-mediated reactions, anaphylaxis, mercury toxicity, and transmission of blood-borne infections), the new formulation of HBIG (NABI-HB; NABI, Rockville, MD) has largely eliminated safety and tolerability concerns. Although licensed for intramuscular use, if administered in large amounts, it can be used intravenously. Several centers use intramuscular HBIG rather than intravenous HBIG either from the beginning or transitioning to it months to years after transplant (82,83,84,85). The benefit of the intramuscular route is that the doses to achieve adequate titers are smaller; 4% to 15% of the 10,000 IU/month high-dose intravenous regimens (82,85). This dose reduction equates to significant cost savings; $52,600 per recurrence prevented compared to $371,000 per recurrence prevented for intramuscular HBIG plus lamivudine and intravenous plus lamivudine, respectively (85). A few differences between intramuscular and intravenous dosing include: (i) Intramuscular injection has a depot effect, so maximal intravenous levels are reached 3 to 5 days post-injection, (ii) 55% to 60% of the antibody diffuses into extravascular compartment, and (iii) the half-life of immunoglobulin G (IgG) given intramuscularly is 25 days, therefore monthly intervals can expect to maintain certain trough levels of anti-HBs (67). Alternative regimens to reduce HBIG requirements (and cost) have included lamivudine monotherapy, low-dose HBIG and lamivudine, and short-term HBIG plus long-term lamivudine, all at varying effectiveness.

Table 58.6. Rates of Hepatitis B Virus Recurrence Using Hepatitis B Immune Globulin in Terms of Initial Diagnosis for Liver Transplantation

Initial liver disease

Recurrence (%)

Acute hepatitis B

0–10

HBV-HDV coinfection cirrhosis

10–20

HBV cirrhosis without HBV replication

20–35

HBV cirrhosis with HBV replication

30–80

HBV, hepatitis B virus; HDV, hepatitis D virus. From references: Shouval D, Samuel D. Hepatitis B immune globulin to prevent hepatitis B virus graft reinfection following liver transplantation: a concise review. Hepatology 2000:32:1189–1195 and Samuel D, Muller R, Alexander G, et al. Liver transplantation in European patients with the hepatitis B surface antigen. N Engl J Med 1993;329:1842–1847.

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▪ Figure 58.3 Generalized summary of prophylaxis regimen to prevent hepatitis B virus (HBV) recurrence after liver transplantation. a Fixed dose regimen. b Alternatively some centers use IM hepatitis B immune globulin (HBIG) or stop IV HBIG after 6 to 24 months.

The development of nucleoside analogs has changed the current standard of care for preventing HBV recurrence. Lamivudine and adefovir are both safe and effective in liver transplant recipients. Both agents have been used alone and in combination with HBIG as prophylactic therapy (Fig. 58.3) and for patients who develop HBV recurrence after liver transplantation (86). The benefit of lamivudine is its low cost and excellent tolerability in cirrhotics and liver transplant recipients. The main disadvantage of lamivudine is resistance (20% after 1 year, 50% after 3 years) (87). Both wild-type and lamivudine-resistant HBV are sensitive to adefovir. Addition of adefovir to lamivudine can reduce HBV recurrence in patients transplanted with lamivudine resistance (86,88). Resistance to adefovir has been described, although the incidence of this resistance is low (3% in the first 2 years of therapy) (86). Entecavir was approved for treating chronic HBV infection in early 2005. Although clinical P.1535 studies in decompensated cirrhotics and liver transplant recipients have not been published, its safety profile and efficacy suggest it will be another antiviral agent to be used pre– and post–liver transplant. The incidence of entecavir resistance is low (1% after 1 year of treatment) and only in patients with preexisting lamivudine resistance (89). Tenofovir, approved for human immunodeficiency virus (HIV), has activity against wild-type and lamivudine-resistant HBV and appears to be safe and efficacious for use in decompensated cirrhosis and liver transplant recipients. Given the associated increased risk of HBV recurrence with demonstrated viral replication pretransplant, it has become standard of care to start patients on nucleoside analogs prior

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to transplantation and to continue their use post-transplant with the use of HBIG (combination therapy). Although use of antiviral therapy pretransplant has been shown to stabilize and improve liver function (in some cases obviating the need for transplantation all together), clinical improvement is slow and may not be helpful in very advanced disease (90,91,92). The optimum timing of initiating lamivudine pretransplant is unclear. Clinical effect can take 3 to 6 months, arguing for early initiation; however, risk for resistance increases with duration of therapy, negating the initial benefit and increasing risk of recurrent HBV after liver transplantation. The development of new nucleoside analogs effective against the YMDD mutation provides additional alternatives (93). The efficacy of lamivudine monotherapy to prevent recurrent HBV infection post-transplant is determined by the HBV DNA status of the patient at the time lamivudine is started. In the North American multicenter trial, 1- and 3-year post-transplant recurrence rates were 40% and 60%, respectively among patients who were HBV DNA positive before initiation of lamivudine therapy compared to 18% and approximately 20%, respectively, among patients who were HBV DNA negative before initiation of lamivudine therapy (94). Whether all patients in this later group of “nonreplicators” were truly HBV DNA undetectable is not known as a relatively insensitive assay (detection limit approximately 10 7 copies/mL) was used. In contrast, a Hong Kong study on lamivudine monotherapy reported only one of 26 patients (3.8%) developing reappearance of HBV DNA in serum after transplantation (58% were either HBV DNA or HBeAg-positive at time of transplant) (95). Some centers have shown good results with sequential prophylaxis with HBIG followed by lamivudine in patients who are HBeAg-negative and/or HBV DNA negative. In one study (96), 24 patients who received at least 6 months of HBIG were randomized to either HBIG (n = 12) or lamivudine (n = 12) for 1 year. Recurrent HBV occurred in 1 of 12 patients on HBIG therapy and 2 of 12 on lamivudine. Another study of 30 patients who were HBeAg-negative prior to transplant were considered for lamivudine substitution after 2 years of HBIG (97). Of the 16 patients who participated in the study, none developed evidence of HBV recurrence after a median follow-up of 13 months. Similar findings were seen in a prospective randomized trial comparing lamivudine monotherapy after 1 month of HBIG (n = 14) and lamivudine with long-term HBIG (n = 15) (98). After 18 months of follow-up all patients survived without HBV recurrence (all patients were HBV DNA negative at the time of transplant with or without use of lamivudine). Further studies are needed to define the subset of patients in whom HBIG can be discontinued and what the risk of lamivudine resistance and virologic breakthrough is with longer follow-up. The combination of HBIG (either intravenously or intramuscularly) with a nucleoside analog appears to be more effective than either agent alone with rates of HBV recurrence ranging from 0% to 18% in patient populations with prevalence of HBeAg/HBV DNA positivity ranging from 34% to 90% (74,82,83,84,99,100,101). As a general rule, the studies showing the greater rates of recurrence (11% (101) and 18% (74)) used lower maintenance doses of HBIG and all patients who developed recurrence had lamivudine resistance prior to liver transplantation. Excluding these studies suggests that use of HBIG with lamivudine (or another nucleoside analog) offers the lowest rate of recurrence ( Table of Contents > Volume 2 > Section XII - Elements of Liver Transplantation > Chapter 60 - Hepatobiliary Complications of Hematopoietic Cell Transplantation

Chapter 60 Hepatobiliary Complications of Hematopoietic Cell Transplantation Josh Levitsky Michael F. Sorrell

Key Concepts z

The most accurate prognostic indicator for the development of severe liver dysfunction is an early rise in liver function tests after hematopoietic cell transplantation (HCT).

z

z

The most common causes of acute liver disease after HCT are acute graft versus host disease (GVHD), drug toxicity, and viral infection. Liver biopsy is often not necessary in classic presentations of GVHD and sinusoidal obstruction syndrome (SOS); however, the absence of full diagnostic criteria or the presence of other potential etiologies may indicate the need for histologic confirmation.

z

Hepatitis B virus (HBV), hepatitis C virus (HCV), iron overload, and chronic GVHD are among the most common etiologies for chronic liver disease after HCT.

z

z

The risk of HBV flare after HCT is highly dependent on the presence of detectable donor or recipient HBV deoxyribonucleic acid (DNA). The degree of hepatic iron overload present after HCT correlates well with the future development of hepatic fibrosis.

z

Hepatic herpesvirus and fungal infections after HCT, although uncommon, can be life threatening and warrant immediate diagnosis and treatment.

Over the last few decades, hematopoietic cell (bone marrow or stem cell) transplantation (HCT) has evolved from an experimental procedure into a lifesaving, potentially curative therapy for patients with a wide variety of hematologic and oncologic diseases. It is now a recognized treatment option for refractory leukemia, lymphoma, thalassemia, aplastic anemia, sickle cell anemia, breast cancer, and immunodeficiency syndromes. Advances in preparative regimens, GVHD prophylaxis, and anti-infective prophylaxis and treatment have brought significant improvements in long-term disease-free survival after HCT. Acute and chronic hepatobiliary complications remain the “Achilles' heel” of HCT and, despite advances in HCT, are responsible for significant morbidity and mortality after transplantation. Pretransplantation evaluation of donors and recipients and close monitoring after HCT reduces the development of severe hepatic complications. This chapter focuses on the specific common and

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uncommon etiologies, diagnosis, and management of these complications.

Prevalence The prevalence of chronic liver disease in HCT recipients varies in the literature, depending on sample size, length of follow-up, and method of diagnosis. Abnormal liver biochemistry test results in the first 12 months are common, particularly in recipients of allogeneic transplants (1). In this period, the most common causes of abnormal liver function in recipients of allogeneic transplants are GVHD, drug hepatotoxicity, and viral hepatitis. In autologous transplantations, disease recurrence and sepsis are predominant. Liver disease P.1558 may be responsible for up to 30% of deaths in HCT recipients (2). Recipients who have unrelated donors or donors with abnormal liver function have an increased risk of developing significant liver disease (2). Chronic liver disease, often due to viral hepatitis, is seen in a high percentage of HCT recipients who survive long term (3). The largest study (>3,700 recipients) of long-term survivors showed a slow progression to cirrhosis (4). The cumulative incidences of cirrhosis 10 and 20 years after HCT were 0.6% and 3.8%, respectively. In comparison to matched controls without cirrhosis, only hepatitis C was found to be more prevalent in recipients.

Donor Evaluation Once a suitable donor is selected, the evaluation should consist of liver function tests and serologic testing for infectious agents that are potentially transmissible to the immunosuppressed recipient (Table 60.1). Most notably, testing for previous exposure to hepatitis B virus (HBV), hepatitis C virus (HCV), and cytomegalovirus (CMV) provides an important estimate of the risk of transmission and the need for closer monitoring or prophylaxis. These etiologies are discussed in further detail in subsequent sections.

Recipient Diagnosis and Evaluation The differential diagnosis of liver disease in this population depends on the specific period after HCT (Fig. 60.1). Liver function tests and clinical signs of liver disease (e.g., right upper quadrant pain, jaundice, ascites, weight gain) should be monitored frequently in the course of post-HCT care. Any suggestion of liver disease should be evaluated immediately as early diagnosis and treatment results in improved prognosis for most etiologies. The initial approach should be to evaluate for infection, review the recent drug history, and screen for viral hepatitis. Imaging tests may be helpful in all stages after HCT, particularly when sinusoidal obstruction syndrome (SOS), complications from gallstones, or the development of cirrhosis are suspected.

Table 60.1. Evaluation of Donor and Recipient in Hematopoietic Cell Transplantation

Donor Liver function tests

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Recipient Liver function tests

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Hepatitis B virus

Surface antibody and

Hepatitis B virus

Surface antibody and antigen

antigen

Core IgG

Core IgG

DNA

DNA

Hepatitis C antibody

Hepatitis C antibody

Cytomegalovirus IgG

Cytomegalovirus IgG

Varicella zoster virus IgG

Epstein-Barr virus IgG

Iron studies

Iron, TIBC, ferritin

Hepatobiliary ultrasonography with vascular Doppler

IgG, immunoglobulin G; DNA, deoxyribonucleic acid; TIBC, total iron binding capacity.

The use and safety of liver biopsy to evaluate abnormal liver function after HCT are debated. Clinical criteria for diagnosing specific etiologies, such as SOS and GVHD, may obviate the need for liver biopsy. However, a significant percentage of diagnoses and management decisions may be altered because of liver biopsy findings, particularly when risk factors for hepatitis B and C reactivation are present (5,6,7,8). Coagulopathy and thrombocytopenia can limit the ability to perform a safe liver biopsy. Percutaneous biopsy can be performed in patients with low bleeding risks (platelets >75,000 and international normalized ratio [INR] 2 mg/dL), and weight gain (>5%) due to ascites formation. The diagnosis is secure in patients who meet these clinical criteria, although those with less than or equal to two criteria are less likely to have SOS and may need liver biopsy for confirmation (94). HVPG greater than 10 mm Hg correlates highly with the histologic diagnosis of SOS and may be useful when the biopsy or clinical scenario is inconclusive (3,7). Noninvasive tests, such as Doppler ultrasonography and magnetic resonance imaging (MRI), may assist in making the diagnosis. Ultrasonographic findings, such as splenomegaly, ascites, low flow in the paraumbilical vein, and an elevated hepatic artery resistive index, correlate with the clinical and histologic diagnosis of SOS (95,96,97). Low portal vein velocity or portal vein thrombosis appear to be somewhat less reliable (79,98,99). Hepatic vein narrowing and gallbladder wall thickening may be seen on MRI in patients with SOS (100). Before HCT, prophylactic strategies to prevent SOS are often employed. The most promising agents are ursodeoxycholic acid, heparin, and defibrotide (101). A pilot study and two of three randomized trials showed a significant reduction in the incidence of SOS with the use of ursodeoxycholic acid compared to placebo (28,102,103,104). Heparin, either unfractionated or low molecular weight, or in combination with defibrotide, is also effective in preventing SOS compared to placebo, with a low rate of bleeding complications (105,106,107,108,109,110). Once SOS has developed, immediate attempts at treatment are required. Response rates depend on early diagnosis and severity of disease. An initial report on the compassionate use of defibrotide for severe SOS showed a response in 8 of 19 patients (111). Subsequent larger studies showed overall and severe disease response rates to be 55% to 76% and 36% to 50%, respectively (85,93,112). Defibrotide is preferred over other thrombolytic agents, such as recombinant TPA, that have a significantly higher rate of bleeding complications (113,114,115,116,117). Other less well-reported treatment strategies include antithrombin III, charcoal hemofiltration, N-acetylcysteine, and prostaglandin E 1 (118,119,120,121). For refractory cases, transjugular intrahepatic portosystemic shunt (TIPS) has been shown to reduce HVPG and improve abdominal pain and ascites but does not generally result in improved survival (122,123,124,125). In select cases, liver transplantation may be performed with a potential for longterm survival, although the data are sparse (53,126,127,128).

Hepatitis B Virus Donor evaluation HBV can be transmitted from donor to recipient and cause acute hepatitis soon after HCT. De novo HBV has been reported to occur in 3.2% of recipients (2). The risk of hepatitis relates to the presence of donor hepatitis B surface antigen (HBsAg) and replicating HBV deoxyribonucleic acid (DNA). (129) Hepatitis B carriers (HBsAg with little or no HBV DNA) less commonly transfer HBV to recipients, causing acute hepatitis (2,130). In recipients who convert from surface antibody positivity to negativity after HCT (reversed seroconversion), acute hepatitis does not occur if the donor is surface antigen negative but may occur if the donor is surface antibody negative (131,132). Adoptive transfer of surface antibody from donor to recipient may result in loss of surface antigen and acquisition of surface antibody by the recipient

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(131,133,134). In addition, donors who are vaccinated before donation may also transfer surface antibody to recipients (134,135). This may be particularly important in preventing acute flares of HBV after HCT and in long-term protection. Core antibody can also be transferred from donor to recipient and result in loss of surface antigen (136).

Risk of reactivation and acute flare The most significant factor for developing severe HBV infection after HCT is the replicative status of the virus immediately before HCT, either in the donor or in the recipient. Recipients with surface antigen and undetectable HBV DNA have a significantly lower risk of reactivation than those with detectable DNA (130,137). Precore or core promoter mutations in the viral genome predispose these patients to more severe reactivation and decompensation after HCT (130). The presence of recipient core antibody also poses a risk, particularly in the setting of detectable DNA and chronic GVHD (138,139). Finally, even patients with surface antibody who have presumed immunity can develop acute hepatitis after HCT, potentially related to low surface antibody titers and the presence of viral DNA in either blood or tissues (140,141). Fulminant hepatic failure can occur if the diagnosis is made late and therapy is not instituted in time (141,142).

Treatment Acute reactivations of HBV, typically in the setting of immunosuppression tapering or withdrawal, are becoming less common with advances in the treatment and prophylaxis of HBV before and after HCT. Lamivudine is typically the first agent selected for HBV flares after HCT, unless the patient has a known lamivudine-resistant strain. In these patients, no data exist about P.1563 treatment with interferon and other agents associated with a low risk of viral resistance (e.g., adefovir, tenofovir, and entecavir). This being said, these agents are often used in patients with lamivudine-resistant HBV for lack of an alternative. Famciclovir, when added to lamivudine, may potentiate the antiviral effect (143). In addition, HBV replication has been shown to be suppressed by ganciclovir, which is given for CMV infection, although use of this drug primarily for HBV is not recommended (144). The length of treatment in all cases is also unknown. Those with reactivation during immunosuppression withdrawal should be treated until immunosuppressive agents are tapered or discontinued and for an undefined period thereafter.

Prevention If possible, patients with chronic HBV should be treated before HCT with the goal of undetectable virus at the time of HCT. In this setting, treatment should be continued in patients long after engraftment and immunosuppression withdrawal. Patients who cannot wait until viral clearance with treatment should be given antiviral prophylaxis as soon as possible, at least 1 week before HCT. Recipients with surface antigen who are given lamivudine prophylaxis have a significantly higher 1-year survival (94% vs. 54%) and lower incidence of hepatitis flares (5% vs. 45%) and acute liver failure (0% vs. 15%) compared to those given no prophylaxis (145,146,147). A small study showed that famciclovir prophylaxis was associated with less reactivation and death than no prophylaxis (148). Another strategy involves vaccinating donors immediately before and/or after HCT. Seroconversion rates are surprisingly acceptable even in the period of

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intense immunosuppression (149). This may prevent HBV flares once seroconversion takes place.

Hepatitis C Virus The prevalence of HCV in HCT recipients is highly variable in the literature depending on patient number, year of publication, and indications for HCT. The largest study involving 63 transplantation centers reported that 5% of HCT patients were HCV antibody positive, although other studies have shown much higher percentages (31% to 51%), particularly in patients with thalassemia (150,151,152). Seventeen percent to 24% of patients are HCV ribonucleic acid (RNA) positive before HCT (67,151,153). HCV has been shown to be the etiologic factor in up to 50% of chronic liver disease after HCT (3). Most HCT recipients acquire HCV from previous blood transfusions, although donor-to-recipient transfer may occur in the setting of high donor HCV RNA levels (154). Transmission of HCV is currently low because of newer-generation HCV antibody testing and treatment of donors (87,155).

Risk of acute flare Unlike HBV, patients rarely develop acute hepatitis or fulminant hepatic failure with withdrawal of immunosuppression after HCT (67,156,157,158). Although a common cause of chronic liver disease, HCV alone is not a predictor of the development of liver failure in patients undergoing HCT (159). However, HCVpositive recipients with abnormal liver enzyme levels before HCT have an increased risk of SOS-related liver failure and death (67,160). Therefore, patients with HCV should be monitored carefully for the development of SOS after HCT.

Treatment Data about HCV treatment after HCT are sparse. One study involved 11 patients, 24 to 65 months post-HCT, who were treated with interferon for 6 to 12 months (161). Ten of 11 completed the protocol; 40% had a sustained virologic response and 50% had improved liver histology. Another smaller study of four HCT patients showed a 50% end-of-treatment response rate at 12 months with ribavirin monotherapy (162).

Long-term prognosis Progressive fibrosis and clinical deterioration from HCV has been reported in multiple studies in HCT recipients (153,163,164,165). The median time to the development of cirrhosis is significantly shorter in HCT recipients—18 years compared to 40 years in non-HCT controls (166). Other studies have shown that HCV does not lead to higher morbidity and mortality long term after HCT (67,167). What might differentiate those with mild liver disease from those with progressive fibrosis is the hepatic iron load, particularly in patients undergoing transplantation for thalassemia. Patients with HCV and heavy iron deposition have a significantly higher incidence of hepatic fibrosis than those without iron deposition (168). Other potential risk factors for progression are HCV genotype and the presence of extrahepatic manifestations of HCV (166,169).

Iron Overload Iron overload may be responsible for a significant percentage of chronic liver disease in patients after HCT (3,170). Hepatic iron content increases shortly after

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HCT and is associated with an elevated ferritin level (171,172). However, progressive fibrosis due to hepatic iron deposition in HCT recipients is most commonly seen in patients with a pre-HCT history of iron overload from multiple blood transfusions (thalassemia) (173). Studies have also shown that the presence of severe iron overload significantly impacts survival and transplantation-related mortality (174,175). Those P.1564 who have hepatomegaly and fibrosis before HCT will invariably develop progressive iron overload and fibrosis years after HCT (173). This degree of progression correlates well with the hepatic iron content and the presence of HCV (168). The diagnosis of iron overload is often made by an elevated ferritin and transferrin saturation. Liver biopsy may not be necessary in the right clinical context, although hepatic iron stores often reflect total body iron stores accurately and may give prognostic information (176). Iron overload suggestion on MRI examination is common after HCT and may correlate with the number of previous blood transfusions (177). Initial detection of significant iron overload may identify those patients at highest risk for adverse post-HCT outcomes. In small studies, early iron reduction with phelobotomy or iron chelation therapy has been shown to be safe and effective in maintaining low ferritin levels immediately after HCT (178,179,180). Iron reduction is, however, better tolerated after HCT when adequate return of red cell production by the bone marrow occurs. Studies have shown significant improvements in ferritin level, transferrin saturation, liver enzyme levels, hepatic iron concentration, and fibrosis scores in patients with undergoing phlebotomy years after HCT (5,176,181).

Common Causes of Cholestasis Sepsis Sepsis of any cause, particularly in the setting of neutropenia or high levels of immunosuppression, may lead to biochemical liver abnormalities and cholestasis (182). The pathophysiologic features of cholestasis of sepsis are similar in the general and transplantation populations. Canalicular cholestasis is the most common histologic finding, typically with dilated periportal ductules and occasionally inspissated bile in cholangioles. Other nonspecific findings include steatosis and pericentral ischemic necrosis, potentially related to poor perfusion from sepsis (183). In severe septic shock, jaundice may be marked. Laboratory studies have shown that cytokine release in the circulation related to bacterial lipopolysaccharides downregulates bile acid transport and bile secretion (184). Ductal obstruction resulting in jaundice can be easily differentiated from cholestasis of sepsis by ultrasonography and histologic features of nonsuppurative cholestatic injury (185). Resolution of sepsis invariably results in normalization of bilirubin and cholestasis.

Total parenteral nutrition Determining that total parenteral nutrition (TPN) is the primary cause of cholestasis after HCT is challenging. Multiple other factors are often present, such as sepsis, drugs, viral infections, and GVHD. Cholestasis related to TPN is much more common and severe in infants compared to older children and adults. Typically in adults, increases in levels of serum transaminases, alkaline

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phosphatase, and γ-glutamyl transpeptidase (GGT) are seen within 3 weeks of TPN initiation and return to normal in over 75% of patients (186,187). The most common histologic abnormalities include intrahepatic cholestasis, portal/periportal fibrosis, and periportal macrovesicular steatosis (188). This fibrosis may persist but does not generally progress after TPN discontinuation. Progression to cirrhosis and the development of clinically significant liver disease is uncommon in adults receiving long-term TPN. The initial management of TPN cholestasis involves reduction of dextrose content in TPN with conversion to more lipid-based calories and cycling infusions to allow “TPN-free” periods to improve biliary flow. Progressive cholestasis, despite these measures, should warrant discontinuation of TPN if possible.

Drugs Numerous medications given after HCT can lead to intrahepatic cholestasis and liver test abnormalities. Hepatotoxic agents cause either dose-dependent intrinsic liver injury or dose-independent idiosyncratic toxicity, often related to an immunologic or metabolic reaction. Many chemotherapeutic agents and corticosteroids can cause steatosis, SOS, cholestasis, and/or hepatocellular injury. Prophylactic or therapeutic anti-infective agents such as sulfonamides, macrolides, cephalosporins, penicillins, and azole antifungals can lead to significant cholestasis, vanishing bile duct syndrome, or phospholipidosis. High doses of nonsteroidal anti-inflammatory drugs (NSAIDs), such as sulindac, diclofenac, and indomethacin, may cause cholestasis and/or hepatocellular injury. Lastly, agents used for GVHD, for example, cyclosporine and less commonly tacrolimus, can lead to cholestasis in the setting of high serum and tissue levels of these agents (189). Histologic changes consist of bile duct epithelium hypertrophy with cytoplasmic vacuoles and foamy deposition within the hepatic sinusoids. In rat models, cyclosporine decreases bile flow and bile salt secretion (190).

Uncommon Complications Herpesvirus Infections Although herpesvirus infections are well described in HCT recipients, the literature, specifically on hepatic involvement, is sparse. Whether this represents a lack of reporting or a true low incidence is unknown. Advances in antiviral prophylaxis and early recognition P.1565 and treatment are major factors lowering the risk of viral dissemination.

Herpes simplex virus 1 and 2 Fulminant hepatitis due to herpes simplex virus (HSV) early after HCT has been reported, although incidence data specific for herpes hepatitis in this population are not available (191). Risk factors for reactivation include pretransplantation conditioning, HSV seropositivity, and a history of leukemia (192). Herpes hepatitis typically causes massive coagulative necrosis with purple nuclear inclusions surrounding the regions of necrosis. Skin lesions are not always present, making the diagnosis more difficult. HSV DNA detected in peripheral leukocytes is more specific for disseminated infection (e.g., esophagitis, hepatitis) and may have predictive value when its level is rapidly rising (193,194).

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Immediate treatment with intravenous acyclovir is warranted. Prophylactic strategies after HCT, including use of acyclovir and its derivatives, have been shown to lower the incidence of HSV infections in general. However, the effect of prophylaxis on viral dissemination, including hepatitis, has not been reported probably because of the low incidence of this complication (195,196,197). Acyclovir- and foscarnet-resistant HSV strains have been increasing with use of prophylaxis, although they have not been associated with a higher risk of dissemination (195,198,199).

Varicella zoster virus The incidence of VZV infections has been declining, likely because of antiviral prophylaxis and less intense immunosuppression (200,201,202). Although the overall incidence of disseminated VZV after transplantation has been reported to be approximately 5%, those who develop skin lesions (chicken pox) have a greater chance (11% to 33%) of subsequently developing organ involvement. (200,203,204). Infections typically occur within the first year of transplantation and often occur in the setting of GVHD, pretransplantation VZV seropositivity, and recent discontinuation of antiviral prophylaxis (37,200,201,203,204,205). Similar to HSV, VZV dissemination without skin involvement can occur in the presence of high VZV DNA levels (206,207). Clinically, patients with VZV hepatitis may present with severe abdominal pain and significant liver enzyme level elevation (208). Fulminant hepatic failure from varicella hepatitis, although uncommon, has been reported after HCT (209). Hepatic lesions are similar to HSV hepatitis, with necrosis and a paucity of significant inflammation. Electron microscopy, immunocytochemistry, and polymerase chain reaction (PCR) analysis may help differentiate VZV from other herpesviruses (183). Morbidity after VZV infections is high. However, with prompt antiviral treatment, death from dissemination is rare (200,203,204,205). Acyclovir is the drug of choice for treatment (210). For prophylaxis, acyclovir reduces VZV reactivation significantly, although VZV can occur soon after prophylaxis is stopped. Longerterm prophylaxis may be considered in patients at high risk for VZV (i.e., previous zoster, GVHD) (201). Varicella vaccination given before and after HCT has been shown to significantly reduce zoster infections and the potential for viral dissemination (211,212).

Epstein-Barr virus Infection with Epstein-Barr virus (EBV) after HCT rarely involves the liver alone. Proliferation of EBV in the setting of high immunosuppression, antilymphocyte therapy, and T-cell depletion results in B-cell proliferation and the potential for post-transplantation lymphoproliferative disorder (PTLD) (213,214,215,216). Critical to controlling EBV proliferation is the presence of CD8 + -specific T cells (217,218). Clinical signs, such as fever, lymphadenopathy, splenomegaly, weight loss, abnormal aminotransferase levels, and bone marrow suppression, are common. Histopathology shows a diffuse lymphocytic infiltrate in the sinusoids and occasionally focal apoptotic cells (219). Rapid increases in serum EBV DNA levels greater than 10 4 is highly associated with the development of PTLD after HCT, suggesting the need for monitoring viral load (220,221,222,223). In addition, rapid reduction in DNA levels with treatment predicts a successful response (224). Studies have shown that preemptive treatment with an anti-CD20 antibody, rituximab, when EBV DNA levels greater than 10 3 or CD8 + responses to EBV are

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detected, may prevent the subsequent development of PTLD (218,225,226). Infusion of EBV-specific cytotoxic T cells at the time of HCT or at peak EBV viral load may reduce viremia and the risk of PTLD (227,228). Polyclonal EBV infections typically respond to reduction in immunosuppression, while various treatments for PTLD have had varied success, including rituximab, standard lymphoma chemotherapy, ganciclovir, and α-interferon (229,230).

Cytomegalovirus Little data exist on the incidence of CMV hepatitis after HCT. A higher rate of CMV infection is seen in recipients of CD34-selected peripheral blood stem cell transplants, alemtuzumab infusions, and transfusions without leukocyte depletion or CMV screening (231,232,233,234,235). Patients may present with a variety of signs and symptoms, including fever, cytopenia, colitis, pneumonitis, and abnormal transaminases. The pathognomonic findings are an enlarged hepatocyte, bile duct epithelium or endothelial cell containing P.1566 cytoplasmic basophilic granules, and an intranuclear inclusion surrounded by a clear halo (“owl's eye”). Blood CMV DNA testing is more sensitive than culture or antigen testing and may predict the development of CMV end-organ disease. Antiviral prophylaxis after HCT, including acyclovir, valacyclovir, ganciclovir, and valganciclovir, are all highly successful in reducing the incidence of CMV infection (236,237,238,239,240). Intravenous ganciclovir is the treatment of choice for known infections, with foscarnet given for known ganciclovir-resistant strains. Another approach (preemptive) is to closely monitor for CMV infection by culture, antigen, or DNA and only treat once CMV is detected (241,242,243). Compared to culture, monitoring CMV DNA frequently after HCT and treating once DNA is detected has been found to reduce the subsequent development of symptomatic CMV disease and related mortality (244,245,246). Isolation and donor transfer of T cells with specific activity against CMV target antigens may reconstitute cellular immunity against CMV and may represent a novel approach for future treatment (247,248).

Human herpesvirus-6 Infection with human herpesvirus-6 (HHV-6) in transplant recipients may result in a lobular, nonspecific hepatitis (183,249). This virus can be transmitted from donor to recipient, resulting in an early post-transplantation hepatitis (250). The detection of HHV6 early after HCT may be associated with delayed engraftment (251). A high percentage of HCT recipients have HHV6 viremia, but symptoms and disease specifically related to HHV6 are uncommon (252). Bone marrow suppression and gastrointestinal involvement are the most common presenting signs. Cidofovir and foscarnet appear to have the highest antiviral activity against HHV6 (253).

Adenovirus Adenovirus infection after HCT is rare but may lead to acute hepatic failure in the setting of induction chemotherapy, high levels of immunosuppression, and GVHD (254,255,256,257,258). Overall, adenovirus infection is seen in up to 5% of recipients and presents in a manner similar to that of CMV, with pneumonia, gastroenteritis, hepatitis, and less commonly encephalitis and hemorrhagic cystitis (257,258). Fulminant hepatic necrosis with intranuclear inclusions is seen. Differentiating adenovirus from HSV hepatitis can be difficult and is aided

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by electron microscopy and immunohistochemical staining (256). Treatment with antiviral agents, such as cidofovir and ribavirin, has had limited success (255,259).

Hepatitis G Virus Hepatitis G virus (HGV) is a transfusion-transmitted flavivirus often seen in HCT recipients with HCV. A significant percentage (15% to 48%) of transplant recipients have detectable HGV RNA levels before and after HCT (153,260,261,262,263). The only real consequence of HGV infection may be delayed transplant engraftment (264). Although higher transaminase levels may be seen in HCT recipients with HGV, clinically significant hepatitis or chronic liver disease is not thought to be caused by HGV alone (261,263,265). The hepatic complications of HGV infection may only be a result of HCV coinfection (153,260). No specific treatment is recommended in HGV-infected HCT recipients. While treatment with interferon for HCV may clear HGV in immunocompetent patients, it is not known whether this occurs in immunocompromised HCT recipients (266,267). It is also not know whether HCV is more difficult to treat in HCT patients with HGV.

Fungal Infections In the early days of HCT, up to 9% of cases were found on autopsy to have fungal involvement of the liver (268). Currently, this entity, particularly hepatosplenic candidiasis, is uncommon after HCT and more commonly seen in patients before HCT. Risk factors for fungal liver involvement after HCT include superficial infections, deep fungal infections, and severe liver dysfunction from SOS or GVHD (268). The most common fungal infections involving the liver are candidiasis, aspergillosis, and zygomycosis, but other mycoses, such as cryptococcosis, histoplasmosis, blastomycosis, and coccidiomycosis, can be seen depending on the regional prevalence. Hepatosplenic candidiasis can present with multiple portal and periportal abscesses and granulomas, with yeast and hyphae present in the sinusoids (183). Before HCT, patients can be treated aggressively with amphotericin to eradicate candidiasis and still successfully undergo HCT (269,270). Aspergilli (Aspergillus fumigates and Aspergillus flavus) can cause hemorrhagic hepatic necrosis and local infarction because of blood vessel invasion (183). Zygomycosis is an infection caused by a group of fungal organisms, such as Rhizopus, Mucor, and Absidia, which can proliferate in the setting of immunosuppression and transplantation. Similar to aspergillosis, widespread vascular invasion from zygomycosis causes ischemic necrosis and multiple, necrotic hepatic nodules. Assessing the size, morphology, and special staining on histology typically confirms the diagnosis of fungus in the liver. Culture of liver tissue and blood, although often of low yield, is the most specific test. Others have proposed using panfungal PCR assays to allow for a rapid early diagnosis (271). Imaging tests such as ultrasonography and computed tomography (CT) P.1567 scan, particularly for hepatosplenic candidiasis, may provide additional evidence for invasive hepatic infections, although the sensitivity is quite low (268,272). Fungal abscesses can only be seen on imaging tests after neutropenia resolves post-transplantation. The treatment of invasive hepatic infections depends on the organism and includes the use of amphotericin B, azole antifungals, and echinocandins. Post-HCT prophylaxis with itraconazole, fluconazole, or low-dose

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amphotericin can significantly reduce the incidence, morbidity, and mortality associated with invasive fungal infections (273,274,275).

Biliary Complications Gallbladder disorders While gallbladder sludge and cholelithiasis are commonly seen in HCT recipients, complications such as cholecystitis, gallstone ileus, and choledocholithiasis are uncommon (98,276). Gallbladder sludge after HCT contains nonspecific residue, calcium-binding protein, and calcium bilirubinate crystals (277). The formation of sludge occurs early after HCT and often progresses to stone formation, unrelated to the conditioning regimen or gallbladder contractility (278). Cholecystitis can occur after HCT in a small percentage of patients with gallstones and is treated with either cholecystectomy or nonsurgical measures (e.g., antibiotics, percutaneous drainage) in poor surgical candidates (279,280). Acalculous cholecystitis is even less common and may be associated with prolonged fasting, SOS, transfusions, and the use of TPN (280,281). If possible, the best chance for survival is cholecystectomy as acalculous cholecystitis is associated with gallbladder wall necrosis and perforation.

Biliary obstruction New hepatobiliary abnormalities are common in the first few months after HCT and are often multifactorial (98). Diagnosing biliary obstruction as a cause of jaundice may be difficult when other disorders are present and bile ducts are not particularly dilated on imaging. The incidence of biliary obstruction after HCT was reported to be 0.1% in one large study involving two major transplantation centers (282). Of the small number of cases reported, the etiologies were biliary sludge, choledocholithiasis, duodenal hematoma, stricture, recurrent malignancy, and EBV-associated PTLD (282). Chronic GVHD and peribiliary chloroma may also cause biliary obstruction (283,284). An experimental model of GVHD in mice has shown that the early nonsuppurative lymphocytic cholangitis may evolve into ductal fibrosis of intra- and extrahepatic bile ducts, similar to that seen in primary sclerosing cholangitis (285).

Tumor Infiltration Recurrent and secondary malignancies can involve the liver after HCT. Leukemia and lymphoma may infiltrate the liver, leading to hepatomegaly and high levels of alkaline phosphatase (286,287,288). Solid cancers occur almost twice as frequently in HCT recipients than the healthy population (289). Hepatocellular carcinoma may occur at a higher rate after HCT in patients with HBV, HCV, or cirrhosis of any cause (289). Bile duct adenocarcinoma leading to obstructive jaundice after HCT has also been reported (290). Biopsy is important in differentiating malignancy from infections and regenerative nodules (291).

Nodular Regenerative Hyperplasia Nodular regenerative hyperplasia is characterized by idiopathic, non-neoplastic nodule formation in the absence of hepatic cirrhosis. Most nodules are less than 1.0 cm in size and distort the hepatic architecture enough to cause portal hypertension. The diagnosis after HCT is often confused with that of SOS and can sometimes only be determined on laparotomy or autopsy (292,293). Ascites is the most common portal hypertensive complication. The etiology is unknown and

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is not thought to be related to age, the underlying disease, or cytoreductive regimens (292). The treatment is directed at the symptoms related to portal hypertension. Nodular regenerative hyperplasia may resolve spontaneously months after HCT and typically does not contribute to significant morbidity or mortality (292).

Annotated References Angelucci E, Muretto P, Nicolucci A, et al. Effects of iron overload and hepatitis C virus positivity in determining progression of liver fibrosis in thalassemia following bone marrow transplantation. Blood 2002;100 (1):17– 21. Established that liver fibrosis progresses rapidly after HCT in patients with HCV and significant hepatic iron overload. Barshes NR, Myers GD, Lee D, et al. Liver transplantation for severe hepatic graft-versus-host disease: an analysis of aggregate survival data. Liver Transpl 2005;11(5):525–31. Recent combined literature and organ transplant database review describing the excellent outcomes of liver transplantation for refractory cases of GVHD. Gooley TA, Rajvanshi P, Schoch HG, et al. Serum bilirubin levels and mortality after myeloablative allogeneic hematopoietic cell transplantation. Hepatology 2005;41(2):345–52. Defined early rise in bilirubin level after HCT as a significant predictor of mortality. Lau GK, Leung YH, Fong DY, et al. High hepatitis B virus (HBV) DNA viral load as the most important risk factor for HBV reactivation in patients positive for HBV surface antigen undergoing autologous hematopoietic cell transplantation. Blood 2002;99(7):2324–30. Underscored the importance of high HBV DNA levels in relation to the risk of significant HBV reactivation after HCT. P.1568 Strasser SI, Myerson D, Spurgeon CL, et al. Hepatitis C virus infection and bone marrow transplantation: a cohort study with 10-year follow-up. Hepatology 1999;29 (6):1893–9. Long-term follow-up study of patients with HCV undergoing HCT: overall, there was no adverse effect on mortality but clear association with the development of SOS. Strasser SI, Sullivan KM, Myerson D, et al. Cirrhosis of the liver in long-term marrow transplant survivors. Blood 1999;93(10):3259–66. Largest study with longest follow-up on the incidence, etiologies, and outcomes of liver disease after HCT.

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250. Lau YL, Peiris M, Chan GC, et al. Primary human herpes virus 6 infection transmitted from donor to recipient through bone marrow infusion. Bone Marrow Transplant 1998;21(10):1063–1066.

251. Maeda Y, Teshima T, Yamada M, et al. Monitoring of human herpesviruses after allogeneic peripheral blood stem cell transplantation and bone marrow transplantation. Br J Haematol 1999;105(1):295–302.

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254. Wang WH, Wang HL. Fulminant adenovirus hepatitis following bone marrow transplantation. A case report and brief review of the literature. Arch Pathol Lab Med 2003;127(5):e246–e248.

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256. Bertheau P, Parquet N, Ferchal F, et al. Fulminant adenovirus hepatitis after allogeneic bone marrow transplantation. Bone Marrow Transplant 1996;17(2):295–298.

257. Carrigan DR. Adenovirus infections in immunocompromised patients. Am J Med 1997;102(3A):71–74.

258. Shields AF, Hackman RC, Fife KH, et al. Adenovirus infections in patients undergoing bone-marrow transplantation. N Engl J Med 1985;312(9):529– 533.

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260. Maruta A, Tanabe J, Hashimoto C, et al. Long-term liver function of recipients with hepatitis G virus infection after bone marrow transplantation. Bone Marrow Transplant 1999;24(4):359–363.

261. Yamada-Osaki M, Sumazaki R, Tsuchida M, et al. Persistence and clinical outcome of hepatitis G virus infection in pediatric bone marrow transplant recipients and children treated for hematological malignancy. Blood 1999;93 (2):721–727.

262. Corbi C, Traineau R, Esperou H, et al. Prevalence and clinical features of hepatitis G virus infection in bone marrow allograft recipients. Bone Marrow Transplant 1997;20(11):965–968.

263. Skidmore SJ, Collingham KE, Harrison P, et al. High prevalence of hepatitis G virus in bone marrow transplant recipients and patients treated for acute leukemia. Blood 1997;89(10):3853–3856.

264. Korn K, Schmidt B, Greil J, et al. Hepatitis G virus (HGV) – association with graft failure after hematopoietic stem cell transplantation? Beitr Infusionsther Transfusionsmed 1997;34:16–20.

265. Ljungman P, Halasz R, Hagglund H, et al. Detection of hepatitis G virus/GB virus C after allogeneic bone marrow transplantation. Bone Marrow Transplant 1998;22(5):499–501.

266. Yu ML, Chuang WL, Dai CY, et al. GB virus C/hepatitis G virus infection in chronic hepatitis C patients with and without interferon-alpha therapy. Antiviral Res 2001;52(3):241–249.

267. Karayiannis P, Hadziyannis SJ, Kim J, et al. Hepatitis G virus infection: clinical characteristics and response to interferon. J Viral Hepat 1997;4 (1):37–44.

268. Rossetti F, Brawner DL, Bowden R, et al. Fungal liver infection in marrow transplant recipients: prevalence at autopsy, predisposing factors, and clinical features. Clin Infect Dis 1995;20(4):801–811.

269. Hoover M, Morgan ER, Kletzel M. Prior fungal infection is not a contraindication to bone marrow transplant in patients with acute leukemia. Med Pediatr Oncol 1997;28(4):268–273.

270. Bjerke JW, Meyers JD, Bowden RA. Hepatosplenic candidiasis – a contraindication to marrow transplantation? Blood 1994;84(8):2811–2814.

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273. Grigg AP, Brown M, Roberts AW, et al. A pilot study of targeted itraconazole prophylaxis in patients with graft-versus-host disease at high risk of invasive mould infections following allogeneic stem cell transplantation. Bone Marrow Transplant 2004;34(5):447–453.

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275. Rousey SR, Russler S, Gottlieb M, et al. Low-dose amphotericin B prophylaxis against invasive Aspergillus infections in allogeneic marrow transplantation. Am J Med 1991;91(5):484–492.

276. Safford SD, Safford KM, Martin P, et al. Management of cholelithiasis in pediatric patients who undergo bone marrow transplantation. J Pediatr Surg 2001;36(1):86–90.

277. Ko CW, Murakami C, Sekijima JH, et al. Chemical composition of gallbladder sludge in patients after marrow transplantation. Am J Gastroenterol 1996;91(6):1207–1210. P.1576 278. Teefey SA, Hollister MS, Lee SP, et al. Gallbladder sludge formation after bone marrow transplant: sonographic observations. Abdom Imaging 1994;19(1):57–60.

279. Kuttah L, Weber F, Creger RJ, et al. Acute cholecystitis after autologous bone marrow transplantation for acute myeloid leukemia. Ann Oncol 1995;6 (3):302–304.

280. Jardines LA, O'Donnell MR, Johnson DL, et al. Acalculous cholecystitis in bone marrow transplant patients. Cancer 1993;71(2):354–358.

281. Wiboltt KS, Jeffrey RB Jr. Acalculous cholecystitis in patients undergoing bone marrow transplantation. Eur J Surg 1997;163(7):519–524.

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284. Rotter AJ, O'Donnell MR, Radin DR, et al. Peribiliary chloroma: a rare cause of jaundice after bone marrow transplantation. AJR Am J Roentgenol 1992;158(6):1255–1256.

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Copyright ©2007 Lippincott Williams & Wilkins > Back of Book > Index > A

A AA See Secondary amyloidosis (AA) AAAs See Aromatic amino acids (AAAs) Abacavir 950 hypersensitivity 951 ABCB4 gene, mutations of 1286 Abdomen, palpating 10 Abdominal distension 1064 Abdominal obesity 378 Abdominal pain 70 830 1204 1354 1394 1417 Abdominal trauma 1210 Abdominal ultrasonography 330 646 1394 Abetalipoproteinemia 1141 Abscess 282 amebic 282 cholangitic 282 pylephlebitic 282 pyogenic 282 Abscess drainage, percutaneous 150–151 Absidia 1566 Absorption 366 Abstinence 895–896 effect of 896 Abuse, drugs of 977 Acalculous cholecystitis 1416–1417 1567 complications of 1416 Acamprosate 895 Acanthocytes 349 351 Acarbose 588 960 Accelerated fibrinolysis 355 Accessory livers 185 Accumulation theory 1071 Aceruloplasminemia, hereditary 1032 Acetaldehyde 874 Acetaldehyde dehydrogenase (ALDH) 884 Acetaminophen 17 231 603–604 616 700 937 960– 963 1009 1010 1013–1014 and alcohol combination of 603

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suicidal/parasuicidal intent 603 for analgesia 604 cause of 603 clinical features of 960–961 and hepatotoxicity 603–604 1012 accidental dosage 604 connection between 604 therapeutic dosage 604 histology of 961 ingested 604 injury 1381 management of 962–963 overdose of 603 604 pain relief 603 poisoning 960 prevention of 962 risk factors for 960 treatment protocol 963 toxicity of 603 effect of ethanol 1014 with therapeutic doses 961–962 Acid-fast bacillus (AFB) 1432 Acidophilic body, high magnification of 255 Acidosis 558 Acid sphingomyelinase (ASM) 1315 Acinar agglomerates 202 202 204 Acinus 183 202 zonal differentiation 206 ACIP See Advisory Committee on Immunization Practices (ACIP) Acitretin 986 Acquired immune system 1015 Acquired immunodeficiency syndrome (AIDS) 36 709 723 925 1220 1406 1434 cholangiopathy 165 173–174 278 1416 ACR See Acute cellular rejection (ACR) Acromegaly 334 ACTG See AIDS Clinical Trials Group (ACTG) Actinomyces, microcolony of 1393 Actinomycosis 1392–1393 hepatic 1392 Actin-scavenging system, component of 617 ActiTest 71 72 Active inflammation, with oxidative damage 1255 Active viral replication 1254 Activin receptor-like kinase (ALK-1) 1179 Actomyosin cytoskeleton, dynamic 1351 1352 Acute alcoholic hepatitis, Kaplan-Meier survival curve 900

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Acute cellular necrosis 874 Acute cellular rejection (ACR) 276 1481 1482 development of 1468 Acute fatty liver 607 Acute fatty liver of pregnancy (AFLP) 1281 1283 1289–1292 cause of 1291 clinical and biochemical findings of 1290 defect of LCHAD, associated with 1281 initial symptoms of 1290 maternal and fetal, outcome of 1290–1291 medical and obstetric management of 1291–1292 pathology of 1289–1290 pathophysiology of 1291 recurrence 1290 thrombocytopenia 1290 Acute hepatitis drug-induced 936–937 with massive necrosis 261 portal areas in 257 with submassive necrosis 260 Acute injury with focal coagulative necrosis 260 with microabscess formation 259 with patchy/confluent coagulative necrosis 260 with zonal submassive/massive coagulative necrosis 260 Acute intermittent porphyria (AIP) 1086 1092 Acute liver failure (ALF) 343 1460 pathogenesis of 343 Acute Physiology and Chronic Health Evaluation (APACHE) 617 II score 1461 Acute porphyria 1092–1097 Acute sickle hepatic crisis (ASHC) 337 Acute suppurative cholangitis 272 Acute tubular necrosis (ATN) 502 Acyclovir 1565 high-dose 604 use of 1565 Addison's disease 334 Adefovir 770 1534 and emtricitabine, combination of 783 resistance 780 risk factors for 780 resistant mutations 780 Adefovir dipivoxil 717 778–780 1403 adverse events of 779–780 dose regimen 779 efficacy of 778–780

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hepatitis B e antigen (HBeAg) loss 779 negative chronic hepatitis 779 positive chronic hepatitis 779 response durability of 779 predictors of 779 treated patients, outcome of 779 Adefovir-resistant, HBV mutants 780 Adenine nucleotide transporter (ANT) 318 Adenocarcinoma 306 metastatic 1218 Adenoma 111 955 1076 1235 hepatic 1202 1214 Adenoma cells 1215 Adenomatosis 1215 hepatic 1217 Adenomatous hyperplasia 1218 1230 Adenomatous hyperplastic nodules 1218 Adenosine 542 1187 Adenosine deaminase 721 Adenosine triphosphatase (ATPase), p-type 1025 P.I-2 Adenosine triphosphate (ATP) 213 367 891 926 1131 depletion of 608 homeostasis 1139 synthesis of 1352 Adenosine-5′-triphosphate 317 depletion 318 Adenovirus infection 604 1566 ADH See Alcohol dehydrogenase (ADH) Adiponectin 409 906 1136 Adipose tissue 1135 Adjuvant therapy 173 ADPKD See Autosomal dominant polycystic kidney disease (ADPKD) Adrenal glands, destruction of 334 Adrenal insufficiency 618 Adrenergic receptors 428 Adrenoleukodystrophy 1140 Adult human albumin 217 Adult Still's disease 336–337 Advisory Committee on Immunization Practices (ACIP) 729 733 Aerobic oxidative phosphorylation 317 AFB See Acid-fast bacillus (AFB) AFIP See Armed Forces Institute of Pathology (AFIP) AFLP See Acute fatty liver of pregnancy (AFLP) AFP See α-fetoprotein (AFP)

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African iron overload 1043 Agarose electrophoresis 1066 Agenesis 195 Aggrecan 396 Agnogenic myeloid metaplasia (AMM) 349 352 AIDS See Acquired immunodeficiency syndrome (AIDS) AIDS Clinical Trials Group (ACTG) 1408 AIDS Pegasys Ribavirin International Coinfection Trial (APRICOT) 1407 AIH See Autoimmune hepatitis (AIH) AIP See Acute intermittent porphyria (AIP) AIPGS See Autoimmune polyglandular syndrome (AIPGS) AL See Light-chain amyloidosis (AL) Alagille syndrome (AS) 175 278 1310 features of 1310 Alanine aminotransferase (ALT) 35 71 105 225 321 332 352 679 682 698 756 924 1187 1319 1381 pretreatment serum 776 elevations in serum levels of 19 Alanine transaminase (ALT) 368 1124 1255 1483 Albendazole 1372 Albumin 49–51 222 366 373 375 502 506 507 560 degradation of 376 effects of 508 hepatic synthesis of 369 synthesis of 50 376 Albumin-bound toxin (ABT) 621 exchange of 621 Alcohol 873–878 882–883 1255 excessive 366 long-term use of 604 effect of 603 Alcohol abuse 887 Alcohol dehydrogenase (ADH) 884 pathway 893 Alcohol metabolism 884–885 Alcohol relapse after liver transplantation, predictors of 1539 Alcohol-use disorders identification test (AUDIT) 887 897 Alcohol withdrawal, treatment of 977–978 Alcoholic cirrhosis 381 894 Alcoholic foamy degeneration 279 Alcoholic hepatitis 19 41 380–381 874 879 890 909 1053 acute 502 507 corticosteroids in 900 treatment of 897–904 Alcoholic liver disease (ALD) 879–909 1294 1548 advanced, development of 882 diagnosis of 886–891

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different stages of 882 disease spectrum of 880 endoscopy in 891 ethnicity 881–882 five-year survival in 897 general screening 886–887 guidelines for daily dietary feeding in 905 histologic characteristics of 883 histologic stages of, progression and potential regression among 881 imaging studies in 890–891 laboratory abnormalities of 887–889 long-term management of 910 liver biopsy in 889–890 liver transplantation for 905–906 results of 908 long-term management of 904–906 metabolic derangements in 904 nutritional therapy in 904 905 nutritional requirements in 904 organ dysfunction in 887 pathogenesis of 891–894 892 physical examination of 887 pathophysiology of, role of cellular and subcellular organelles in 893 prognostic factors of 894–896 progression of 880 fibrosis 886 recurrent 1525 1539 risk factors for 881–886 diet 884 gender 883–884 genetic 884–885 malnutrition 884 relative 885 role of, liver biopsy in 891 therapy for 896–906 treatment options for 906–907 typical laboratory abnormalities in 891 Alcoholic liver injury, risk of 883 Alcoholic steatohepatitis (ASH) 319 Alcoholism 880 characteristics of 882 ALD See Alcoholic liver disease (ALD) ALDH See Acetaldehyde dehydrogenase (ALDH) Aldosterone 499 502 504 507 kaliuretic effect of 547 and norepinephrine levels 538 Alemtuzamab 1477

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ALF See Acute liver failure (ALF) Alfuzosin 979 Alkaline phosphatase (ALP) 41–46 1409 biliary retention of 44 correlation with γ-glutamyl transpeptidase 45 hepatic, isolated elevations of 45 isoenzymes 42 placental 44 precise function of 42 tissue-unspecific 41 Allogeneic hepatocytes, transplanted 626 Allograft dysfunction 724 1482 Allograft rejection 276 277 1468 diagnosis of 276 empiric treatment of 1528 Allograft vasculopathy 1486 Allopurinol 966 1440 1493 Allorecognition, direct pathways of 1468 Almitrine 518 ALP See Alkaline phosphatase (ALP) α 1 -antichymotrypsin deficiency 290 α 1 -antitrypsin (α 1 -AT) 317 biosynthesis of 1070–1071 deficiency 252 266 289 290 322–323 1063–1079 1321 altered migration of 1063 diagnosis of 1077 genetic counseling 1079 incidence of 1063 liver disease associated with 1064 1064 management of 1063 population screening 1079 treatment for 1077–1079 variants of 1069 distribution and clearance of 1071 function of 1068–1070 gene structure of 1065 globules of 247 248 human serum samples, isoelectric focusing of 1068 null variants of 1069 in PIZZ individuals, deficiency 1071–1075 plasma concentrations of 1070 protein structure of 1066 sheet and reactive-site loop of 1067 structural variants of, protease inhibitor system for classification of 1066–1067 structure of 1066 variants of 1066

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α-adrenergic antagonists 428 450 α-adrenergic receptor blockers 428 α 1 -AT See α 1 -antitrypsin (α 1 -AT) α-fetoprotein (AFP) 112–113 834 1266 concentration 1254 measurements 112 and ultrasound 113 α-ketoglutarate dehydrogenase 577 inhibition of 611 ALS See Antilymphocyte serum (ALS) ALT See Alanine aminotransferase (ALT) Aluminum contamination 380 Alveolar echinococcosis 1246 Alveolar hydatid disease 1373 Alverine 979 Alzheimer's disease 1070 Amanita phalloides poisoning 204 607 use of antidotes in 607 AMAP See N-acetyl-m-aminophenol (AMAP) AMAs See Antimitochondrial antibodies (AMAs) Amebiasis 1352 P.I-3 Amebic abscess 282 Amebic liver abscess (ALA) 1351–1353 1353 clinical manifestations of 1352–1353 diagnosis of 1353 epidemiology of 1351–1352 pathogenesis of 1352 therapy for 1353 vaccination 1353 Amebic trophozoites 284 American society for gastrointestinal endoscopy (ASGE) 159 American Society of Transplant Surgeons (ASTS) 1517 Amino acids branched-chain 585 parenteral and enteral branched-chain 383 Aminoaciduria 1035 Aminoglycosides 503 Aminopropylation 904 Aminopyrine breath test 30–34 Aminotransferases (ATs) 35–41 54 935 hepatic abnormalities 380 measurement of 37 in patients with infectious hepatitis and obstructive jaundice 38 serum 35 Amiodarone 291 Amiodarone recipients 953

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Amiodarone toxicity, prevention of 953 AMM See Agnogenic myeloid metaplasia (AMM) Ammonia 369 571–572 577 611 detoxification of 575 exposure to 611 effects on nervous tissue 573 fixation of 589 neuropsychiatric effects of 611 Ammonia levels, arterial 624 Ammonia metabolism 368 Amnesia 62 Amoxicillin–clavulanic acid 19 Amphotericin 1391 Amphotericin B 1567 Ampulla of Vater 65 133 193 194 Amyloid 251 340 deposition, intra-acinar 299 fibrils 339 Amyloid-β peptide 1070 Amyloidosis 298 329 339–340 categories of 339 familial 339 hepatic 339 340 clinical symptoms of 339 diagnosis of 340 management of 340 presence of 298 primary (type AL) 298 secondary (type AA) 298 Anabolic steroids 903–904 954–956 benign neoplasms 955 cholestasis 955 clinical trials of 903–904 hepatocellular carcinoma (HCC) 955–956 high-dose 955 rationale for 903 ANAs See Antinuclear antibodies (ANAs) Anastomosis, vein-to-vein 490 Anastomotic strictures 1485 ANCA See Antineutrophil cytoplasmic antibody (ANCA) Androgen steroids 1214 Android obesity 378 Anemia 840 1049 1355 1409 hemolytic 840 ribavirin-induced 840 Anergy 1469 Anesthesia 701

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halogenated agents 701 Anesthetic agents 956–958 halothane 956–958 Angiographic embolization 163 Angiography 128–133 423 1207 1219 1257 1392 catheter-based 128 conventional 128 Angiomyolipoma 1220 Angioplasty 127 138–140 Angiosarcoma 307 307 941 Angiotensin 551 Angiotensin II 402 428 499 542 infusion of 450 receptor antagonists 952 Angiotensin receptor blockers (ARBs) 1150 Anorexia 5 7 372 830 831 1386 Anorexia nervosa 374 376 ANT See Adenine nucleotide transporter (ANT) Antiameba therapy 1353 Antiandrogenic therapy 1260 Antiapoptotic proteins 317 Antiarrhythmic drugs 952–953 amiodarone 952–953 Anti–asialoglycoprotein receptor (anti-ASGPR) 869 Antibiotic intravenous 65 use of 151 Antibiotic prophylaxis 562 Antibiotic therapy 1355 1386 1387 Antibody therapies, in liver transplantation 1476–1477 Anticardiolipin antibodies 668 Anticlotting factors, deficiencies of 612 Anticoagulants 953–954 Anticoagulation 423 1171 1539 Anticonvulsants 603 971–973 phenytoin 971–972 Anticytokine therapy 879 900–901 rationale for 900 Antidepressant 974 monoamine oxidase inhibitors 974 tricyclic 974 Antidepressant drugs 973–974 Antidiabetic agents 1147 Antidiuretic hormone (ADH) 544 levels 538 renal effect of 554 secretion of 548

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Antidote therapy, basis for 962 Antiendomysial antibodies 1141 Antifibrinolytics 357 Antifibrotic therapies 395 rationale for 407–410 specific agents for 407–410 Antifungal drugs 948–949 ketoconazole 948–949 liver injury associated with 949 terbinafine 949 Antigen, source of 1469 Antigen-presenting cells (APCs) 866 1468 Antihepatitis B core antibody (Anti-HBc) 746 753 immunoglobulin (Ig) M class, titers 753 presence of 753 Antihepatitis B core individuals, isolated 751 Anti-hepatitis D virus (anti-HDV), development of 787 Antihistamines 671 H 1 receptor antagonists 978 Antihyperlipidemic agents 1150 Anti-inflammatory drugs nonsteroidal 963–966 liver injury associated with 964 Anti-inflammatory therapy 879 Antileishmanials 1361 Anti–liver/kidney microsomal (LKM) antibodies 1015 Antilymphocyte serum (ALS) 1476 Antilymphocyte therapy 1483 Antimicrobial agents 943–946 amoxicillin–clavulanate (Augmentin) 944 cloxacillin 944 cotrimoxazole 945 dapsone (4,4-diaminodiphenylsulfone) 945 dicloxacillin 944 erythromycins 946 fansidar 945 hepatic injury associated with 943 minocycline 944–945 nitrofurantoin 945–946 oxacillin 943 penicillins 943 quinolones 944 sulfasalazine 945 and mesalamine 945 sulfonamides 945 tetracycline 944 Antimicrobial prophylaxis 1551

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Antimitochondrial antibodies (AMAs) 272 679 934 1536 Antineoplastic effects 1475 Antineutrophil cytoplasmic antibody (ANCA) 668 1329 Antinuclear antibodies (ANAs) 668 683 866 945 1129 Antioxidants 408 901 1146–1147 clinical trials of 901 rationale for 901 Antiphospholipid antibody syndrome (APS) diagnosis of 336 hepatic manifestations of 336 primary 336 Antiproliferative effects 1475 Antipsychotic agents 973–974 Antipyrine metabolism 1096 Antirejection therapy 1482 Antiretroviral agents, use of 607 Antiretroviral therapy (ART) 950–951 1401 hepatotoxicity associated with 1411–1412 Antiretroviral treatment, highly active 942 Antisense molecules 783 Antispasmodic drugs 979 alverine 979 Antistaphylococcal antibiotics 552 P.I-4 Antithrombin 354 Antithrombin deficiency 1072 Antithrombin III deficiency 290 Antithymocyte globulin 1472 1476 Antithymocyte immunoglobulin 1483 Antithyroid drugs 956 Antituberculosis chemotherapy 947 Antituberculosis drugs isoniazid 946–947 clinical features of 947 frequency of 946–947 management of 947 outcome of 947 prevention of 947 risk factors for 946–947 pyrazinamide 948 rifampin 947–948 Antituberculous chemotherapy 603 Antituberculous drugs 946–948 1383 Antituberculous therapy 947 Antiviral agents 605 to liver, selective targeting of 783 treatment with 1566

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Antiviral approaches 783–784 antisense approaches 783 short interfering RNA 783–784 Antiviral defenses, innate host 814–815 Antiviral effects 780 Antiviral prophylaxis, after hematopoietic cell transplantation (HCT) 1566 Antiviral therapy 405 765 837–846 905 1253 1409 IFN-based 845 after liver transplantation 1532 preemptive 1530 Aortal–portal fistulae 424 APACHE See Acute Physiology and Chronic Health Evaluation (APACHE) APCs See Antigen-presenting cells (APCs) Aplastic anemia 606 759 Apoenzyme 35 Apolipoprotein 370 647 Apoptosis 254 313–317 320 321 403 410 608 866 871 1011 1136–1138 Fas-induced 322 hepatocellular, extrinsic and intrinsic pathways of 608 modulation 324 Apoptotic bodies cellular degeneration and death with 255 membrane-bound 313 Apoptotic cascade 319 Appendicitis 702 APRI See Aspartate aminotransferase to platelet ratio index (APRI) APRICOT See AIDS Pegasys Ribavirin International Coinfection Trial (APRICOT) Aprotinin 359 APS See Antiphospholipid antibody syndrome (APS) Aquaretic drugs 554 Arachidonic acid, metabolites of 505 ARBs See Angiotensin receptor blockers (ARBs) Area under operator characteristics curve (AUROC) 71 Areflexia 372 Arginine 51 Arginine vasopressin (AVP) 499 hypersecretion of 504 Armed Forces Institute of Pathology (AFIP) 1434 Aromatic amino acids (AAAs) 382 ARPKD See Autosomal recessive polycystic kidney disease (ARPKD) Arrhythmia 1035 Arsenic 425 ART See Antiretroviral therapy (ART) Arterial ammonia 590 Arterial angioplasty, in hepatobiliary disease 138–139

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Arterial buffer response, arterial 205 Arterial embolization, percutaneous 424 Arterial hypertension 581 942 Arterial hypotension 504 509 Arterial hypoxemia 519 Arterial injury, hepatic 1191 Arterial malformation 1202 Arterial obstruction 1260 Arterial oxygenation 518 Arterial puncture 582 Arterial system, hepatic 143 Arterial vasodilatation 505 peripheral hypothesis 540 splanchnic 504 505 Arteriography, hepatic 127–129 Arteriographic portography 130 Arteriohepatic dysplasia 1310 Arterioles 183 Arterioportal fistulae, intrahepatic 424 Arteriovenous fistula (AVF) 137 and embolization 144 intrasplenic 424 in portal venous system 424 Arteriovenous malformations (AVM) 1335 Arteriovenous shunting 1213 1217 Artery, hepatic 875 Artery injury, hepatic 143 Arthralgia 830 831 841 1035 Arthritis 6 688 968 1035 AS See Alagille syndrome (AS) Ascariasis 174 Ascaris 1359 1362 Ascaris lumbricoides 174 1362 Ascites 14–15 18 333 340 374 375 422 488 497–499 502 506 530– 555 1193 1231 1233 1255 1290 1519 1567 arterial pressure 541 biliary 533 causes of 530 531 circulatory dysfunction associated with 529 in cirrhosis 531 management of 546–548 pathogenesis of 544–546 source of 535–537 clinical aspects 530–534 long-term control of 553 detection of 531 diuretic-resistant 551

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etiology of 530–531 formation of 544 in cirrhosis 544 disorder in 534 forward theory “Forward” theory 545 local intra-abdominal factors in 534–538 renal and circulatory dysfunction, role of 537–544 forward theory of 544–546 management of diuretic treatment, continuous 553 sodium restriction 546 mobilization of 546 with diuretics 548 pancreatic 533 pathogenesis of 545 “forward” hypothesis 545 due to portal hypertension 531 recidivant 551 refractory, management of 551–553 treatment of 546 553–555 Ascitic fluid 550 reabsorption of 537–538 ASGE See American society for gastrointestinal endoscopy (ASGE) ASH See Alcoholic steatohepatitis (ASH) ASHC See Acute sickle hepatic crisis (ASHC) ASM See Acid sphingomyelinase (ASM) Aspartate aminotransferase (AST) 35 71 225 320 332 352 679 682 698 756 869 947 1187 1319 1411 1547 enzymatic assays of 35 patient percentage 40 serum 887 ratio to alanine transferase 38 Aspartate aminotransferase to platelet ratio index (APRI) 71 Aspartate transaminase (AST) 368 1124 1255 1483 Aspergillosis 1566 Aspergillus 259 Aspergillus fumigatus 1415 Aspirin 503 518 542 965 1177 1539 AST See Aspartate aminotransferase (AST) Asterixis 15 580 techniques for 16 Astrocytes 574–576 578 1029 alzheimer type II 575 swelling of 575 Astrocytosis 1029 Atazanavir 231 Atelectasis 1353

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prevention of 1268 Atherosclerotic disease, peripheral 138 ATN See Acute tubular necrosis (ATN) Atorvastatin 954 Atovaquone 1484 ATP See Adenosine triphosphate (ATP) ATP7B, screening for mutations of 1025 ATPase See Adenosine triphosphatase (ATPase) Atracurium 613 Atrophic hepatocytes 210 Atrophy chronic ischemia, secondary to 295 segmental 296 ATs See Aminotransferases (ATs) Atypical adenomatous hyperplastic nodules 1218 AUDIT See Alcohol-use disorders identification test (AUDIT) AUROC See Area under operator characteristics curve (AUROC) Autoantibodies 682–683 841 868 878 Autoantigens 885 Autoimmune cholangiopathy 683 685 Autoimmune diseases, recurrent 1452 Autoimmune hemolytic anemia 704 Autoimmune hepatitis (AIH) 264 267 683 732 865–872 878 927 1065 P.I-5 1188 1328 1486 1536 1538–1539 1548 clinical presentation of 867 definition of 865–866 diagnosis of 867 868 1538 epidemiology of 866 extrahepatic autoimmunologic disease associations of 867 history of 865–866 natural course of 867–869 pathophysiology of 866–867 patients with 263 prognosis of 867–869 treatment of indications for 869 current options 870 treatment strategies for 870–871 Autoimmune polyglandular syndrome (AIPGS) 1328 Autonomic dysfunction 1093 Autophagosomes 1075 Autosomal dominant polycystic kidney disease (ADPKD) 1229 1236 Autosomal recessive polycystic kidney disease (ARPKD) 1229 1241 1309 Aversion therapy, drugs used in 977–978 AVM See Arteriovenous malformations (AVM)

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AVP See Arginine vasopressin (AVP) Azathioprine 689 690 869 970 1173 1295 1472–1473 1493 side effects of 1473 therapy 870 use of 1470 1473 Azidothymidine (AZT) 1011 1403 Azithromycin 946 Azotemia 558 Azygos blood flow magnetic resonance angiography, phase-contrast 440 measurement of 440 application of 440 direct 440 Azygos vein, retrograde catheterization of 440

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Editors: Title:



Copyright ©2007 Lippincott Williams & Wilkins > Back of Book > In dex > B

B Bacillary angiomatosis 297 Bacillary peliosis hepatis 1417 Bacillus cereus, emetic toxin 606 Bacteremia 558 1379 1385 Bacteria 284 645–646 development of quinolone-resistant, problem of 563 intestinal 645 Bacterial cholangitis 651 acute 650 Bacterial infection 502 1379–1380 1394 culture-proved 612 infecting organisms 612 nosocomial 463 specific 1380–1385 susceptibility to 612 Bacterial peritonitis 70 558 Bacterial toxins 667 Bacterial translocation 556 causes for 556 Bad 317 Bak 317 BAL See British anti-Lewisite (BAL) Balloon angioplasty, transluminal 424 1177 Balloon degeneration 1119 Balloon dilatation 166 699 endoscopic treatment with 654 Balloon occlusion technique 437 Balloon tamponade 454 466–467 474 Ballooning 890 1136–1138 Ballooning degeneration 254 255 1381 Banding ligation 459 endoscopic, efficacy of 459 Banding replacing injection 486 Banti's syndrome 425 Barbiturates 47 Barcelona Clinic Liver Cancer (BCLC) 1257 staging of 1258 Bariatric surgery 1140 Baroreceptors 548 Bartonella henselae 298 1172 1394 1417 1437–1438 catscratch disease, associated with 1180 Basal ganglia 573 577 589 592 1023 Basic fibroblast growth factor (bFGF) 398 Basiliximab 1476 Basolateral uptake 1007 Bax 317 BCAA See Branched-chain amino acid (BCAA) B-cell epitopes 811 B-cell lymphoma 1417 Bcl-2 family proteins 317 323 divisions of 317 BCLC See Barcelona Clinic Liver Cancer (BCLC) BCOADC See Branched-chain 2-oxoacid dehydrogenase complex (BCOADC) BCS See Budd-Chiari syndrome (BCS) BDG See Bilirubin diglucuronide (BDG) Beckwith-Weideman syndrome 1336 Benign focal lesions 1201 of bile duct origin 1218–1219 Benign lipomatous tumors 1220–1221 Benign and malignant tumors, cystic disorders 1201–1222 Benign mesenchymal tumors 1219–1220 Benign prostatic hyperplasia 979 Benign recurrent intrahepatic cholestasis (BRIC) 231 237 270 646 1286 1322 Benign stricture benign dilatation 141 management of 170 Benign tumors, surgical options 1265–1275 Benzbromarone 966 Benzoate 589

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Benzodiazepines 614 exogenous 588 natural 573 Beryllium disease 1441 Beryllium poisoning 1441 β-adrenergic blocker nonselective 450 use of 522 β-blockers isosorbide-5-mononitrate (IMN), randomized clinical trials 470 nonselective 451–452 456–457 468 β-carotene 1106 Betaine (trimethylglycine) 1147 β-interferon 980 β-oxidation 973 β-thalassemia 648 Bezafibrate 690 bFGF See Basic fibroblast growth factor (bFGF) BGP-1 See Biliary glycoprotein I (BGP-1) Biglycan 396 Bile in acinar bile duct 270 biochemical composition of 645 cholesterol saturation in 643 components of 640–642 desaturation of 655 microscopic examination of 651 Bile acid 28 317 322 1089 Bile acid metabolism, disorders of 1317 Bile acid tests 28–30 serum 29 Bile acid transporter, apical sodium-dependent 642 Bile canaliculi 193 199 237 303 central 187 Bile duct 24 271 damage of, immune-mediated 668 extrahepatic, distal obstruction of 135 inflammation of 666 intrahepatic 1064 irregular filling defects, endoscopic retrograde cholangiopancreatographic finding of 65 lesions 673 metallic stent 163 pigment stones, formation of 672 plastic stents 163 plugging of 378 surgical reanastomosis of 135 Bile duct adenoma 304 305 intrahepatic 1218 Bile duct cells, fluorescence in situ hybridization of (FISH) 673 Bile duct cysts 300 Bile duct hyperplasia 378 Bile duct injury 407 939 944 1536 Bile duct lesions hepatitis-associated 264 267 large duct 939 Bile duct obstruction 44 56 640 648 acute 36 extrahepatic 20 Bile duct paucity syndromes 1309–1310 Bile duct segment associated with fibrocystic disease 1236 Bile duct stones endoscopic ultrasound 105 patients with 104 treatment of 655–656 Bile duct stricture 45 benign 169 malignant 172 Bile ductal epithelium abnormalities of 257 Bile ducts 183 189 193 275 276 1191 arterial supply of 194 histology of 194 interlobular 1241 intrahepatic 195 paucity of 1309 mucosa of 194 Bile ductular cholestasis 273

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Bile lake 271 273 Bile leaks 170 654 management of 167 Bile peritonitis 65 Bile pigment 270 288 Bile plugs, multiple 270 P.I-6 Bile salt export pump (BSEP) 237 1322 Bile salts 641 formation of 641 primary 642 synthesis of 641 Bile secretion 642–643 Bilhemia 167 Biliary ascariasis 1362 Biliary ascites 533 Biliary atresia 195 372 classification of 174 extrahepatic 277 1064 neonatal 195 Biliary balloon dilatation (Cholangioplasty) and stenting 140 Biliary calculi 25 Biliary cast syndrome 170 Biliary catheter, percutaneous, placement of 141 Biliary cirrhosis 45 165 277 365 665 1245 end-stage 276 primary 6 206 371 372 1032 Biliary colic 639 Biliary complications 1499–1502 after hematopoietic cell transplantation (HCT) 1567 living-related transplantation 1502 Biliary disease contemporary assessment of 133 infections 173–174 Biliary drain 173 Biliary drainage 201 202 percutaneous transhepatic 137 Biliary duct, anastomosis 170 Biliary ductal systems extrahepatic 1186 intrahepatic 1186 Biliary ductopenia 949 Biliary ductular lineage 1077 Biliary enteric anastomosis 1244 Biliary epithelial cells 944 Biliary excretion 27 35 217 hepatic 1023 studies of 235 Biliary fistula 384 Biliary glycoprotein I (BGP-1) 303 Biliary hamartoma 1219 Biliary injury 939 Biliary intervention, percutaneous 127 Biliary leaks 167 1501 Biliary lipid 641 649 bacterial degradation of 649 hydrophobic 645 secretion of 640–643 Biliary manometry 141 Biliary microhamartoma 1238 1242 Biliary obstruction 34 46 65 127 133 136 160 277 1219 1567 benign 164–167 diagnosis of 1567 extrahepatic 343 intrahepatic 342 malignant 171–173 diagnosis and staging 171–173 endoscopic management of 173 mechanical 275 Biliary phosphatidylcholine, bacterial degradation of 649 Biliary reconstruction 1519 Biliary scintigraphy 232 Biliary secretion 201 Biliary sepsis 136 Biliary sludge 649 Biliary stasis 1354 Biliary stent 171 173

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internal 142 Biliary stricture 140 141 165 672 699 1482 1500 1502 1521 benign 141 and injuries 171 dominant, evidence of 672 intrahepatic 136 141 1485 malignant 142 143 dilatation of 173 nonanastomotic 1537 Biliary system 193–195 surgical implications of 195 variations of 195 Biliary tract acquired disorders of 1329–1330 canalicular membranes into 27 disease 6 in pregnancy 1292–1293 infections of 1416–1417 obstruction 199 227 stones 104 Biliary tree 199 Biliary tumors 304–307 Bilirubin 5 20 213 214 217 270 488 1482 1551 abnormalities in binding 227 albumin-bound 25 aqueous insolubility of 221 canalicular excretion of 221 chromatograms of 24 clinical physiology of 222–223 conjugated 26 222 225 647 648 biliary excretion of 234 hypersecretion of 639 value of 23 decreased clearance of 226–227 δ 23 direct-acting 20 direct-reacting 22 224 formation of 21 glucuronidation 221 glucuronides 26 221 hepatic disposition of 220–221 hepatocellular transport of 220 increased production of 226 indirect-reacting 22 224 225 isomers 217 219 metabolism of 20–22 54 213–237 disorders of 1317–1318 overproduction of 704 in plasma 217–219 plasma transport of 214–215 presence of 26 radiolabeled 222 sources of 214–215 structure of 22 214–215 218 transfer of 220 unconjugated 26 218 222 224 224 225 228 uptake, scheme of 21 urinary 26 222 van der Bergh fractionation 54 Bilirubin diglucuronide (BDG) 213 Bilirubin monoglucuronide (BMG) 213 Bilirubin production, quantitative aspects of 216–217 Bilirubin translocase (BTL) 220 Bilirubin uptake 220 hepatocellular 220 Bilirubin-IXα, structure of 217 Bilirubinemia 231 Bilirubinuria 54 232 233 Biliverdin 213 214 1088 Biliverdin reductase 215 216 Billroth II partial gastrectomy, patient with 168 Bilobar biopsy 1175 Bilomas 1482 Bim 317 Bioactivation 1006 Bioartificial liver device 624 Biochemical dysfunction 1482

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Biochemical tests, abnormal hepatic 74–75 Biochemical values, determination of 562 BioLogic-DT system 620 treatment with 623 Biopsy follow-up 269 limitations of 1132 noninvasive surrogates for 71–72 scoring of 1132–1133 utility in specific clinical situations 73 Biopsy sampling error 1131 Biopsy specimen 245 251 examination of 245 246 Bithionol 1369 Biventricular failure 1195 Black pigment gallstones 647–648 formation of 648 Bland cholestasis 938 944 Bleeding 53 64 70 137 356 1213 intraperitoneal 137 mucosal sites of 356 outcomes in patients with abnormal coagulation 358 risk of 615 subcapsular 107 symptomatology 356 variceal 356 358 Bleeding diathesis 612 615 Bleeding varices, endoscopic treatment of 615 Blind percutaneous liver biopsy 1382 Blood donor, screening of 746 Blood flow femoral, Doppler ultrasonography 454 hepatic 439–440 portal, increased vascular resistance 426–427 splanchnic decrease, pharmacologic agents 451 Blood lactate levels 618 Blood sugar levels 91 Blood transfusion 335 620 731 Blood urea nitrogen (BUN) 1354 Blood vessels, scanning electron micrograph of 199 Blood volume, replacement of 462 Blood-borne infections, risk of nosocomial transmission of 826 Blood-filled cysts 200 B lymphocytes 54 BMD See Bone mineral density (BMD) BMG See Bilirubin monoglucuronide (BMG) Body mass index (BMI) 72 367 1117 1124 1493 normal 1126 Bolus 383 Bone disease 1494–1495 metabolic 671–672 Bone marrow 370 1103 1306 1426 1432 P.I-7 failure of 606 suppression of 606 Bone marrow transplantation 942 Bone mineral density (BMD) 372 1494 Bone scintigraphy 1257 Borderline nodules 1218 Bosentan 410 522 979 Bouveret's syndrome 651 Bowel perforation 70 Bowel syndrome, irritable 979 Bradycardia 581 1388 Brain magnetic resonance image of 1034 susceptibility of 580 T1-weighted magnetic resonance image of 574 Brain disease 1023 Brain edema 572 577–578 581 Branched-chain 2-oxoacid dehydrogenase complex (BCOADC) 682 Branched-chain amino acid (BCAA) 381 902 Breath tests 30–35 aminopyrine 30–34 galactose 33 BRIC See Benign recurrent intrahepatic cholestasis (BRIC) Bridging fibrosis 266 1029

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Bridging necrosis 261 937 British anti-Lewisite (BAL) 1024 Broad-spectrum antibiotic 614 Bromocriptine 589 Bromfenac 964 Bromsulphalein (BSP) 20 Brown pigment gallstones 648–649 Brucella melitensis 1384 Brucellosis 1382–1384 1429 1438 acute 1384 Bruits 13 causes of 13 epigastric 13 Brunt score 1132 BSEP See Bile salt export pump (BSEP) BSP See Bromsulphalein (BSP) BSP/bilirubin binding protein (BSP/BR-BP) 220 BTL See Bilirubin translocase (BTL) Budd-Chiari Syndrome (BCS) 19 101 129 134 192 209 296 297 336 338 349 352 426 489 607 618 876 941 1171 1174 1194 1220 1231 1233 1334 1525 acute, diagnosis of 532 associated with hypercoagulable states 1172 development of 353 etiology of 1172 with hyperplasia 100 interventional radiology 1177 liver biopsy 1175–1176 magnetic resonance imaging (MRI) gadolinium-enhanced 1175 of liver 1176 management of 1178 medical therapy 1176–1177 pregnant women, prognosis for 1293 recurrent 1539 and related disorders 1172–1179 clinical presentation of 1173–1174 diagnostic evaluation of 1174–1176 etiology of 1172–1173 laboratory investigation of 1174 management of 1176–1179 medical imaging of 1174–1175 pathology of 1173 secondary 1172 sinusoidal hypertension of 1178 subtypes of 1173 surgical decompression 1177–1178 thrombophilic states 1173 treatment for, liver transplantation 1178–1179 venography 1175 veno-occlusive disease 1175 women 1173 Budesonide 690 870 Bulging flanks 14 Bullous pemphigoid 1068 Busulfan, pharmacokinetics of 1561 Byler's disease 1322

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Editors: Title:



Copyright ©2007 Lippincott Williams & Wilkins > Back of Book > Index > C

C C282Y homozygotes 1050 nonexpressing 1050 C282Y mutation 1045 in hemochromatosis gene (HFE) 1044–1045 prevalence of 1045 Cachexia 367 Cadaveric donor hepatectomy 1511–1512 livers from 1274 organs 602 Cadaveric liver transplantation, historic perspective of 1513–1517 Cadaveric organ 1512 Caffeine clearance 34 CAGE (cut down, annoyed, guilty, and eye-opener) 7 887 CAH See Chronic active hepatitis (CAH) Calcineurin inhibitors (CNIs) 1481 1493 1497 1504 in liver transplantation 1477 Calcineurin nephrotoxicity 1450 Calcitonin 193 672 1495 Calcium bilirubinate 645 649 Calcium channel blockers 451 522 Calnexin 1073 1075 Calorimetry, indirect 368 Calpain 1012 Calreticulin 1073 cAMP See Cyclic adenosine monophosphate (cAMP) Campath 18 1476 1477 Campylobacter 1394 CAMs See Complementary and alternative medicines (CAMs) Canalicular cholestasis 949 1564 Canalicular excretion 220 Canalicular multispecific organic anion transporter (cMOAT) 221 Canaliculi, in isolated hepatocyte doublets 199 Cancer chemotherapy 707 Cancer of the Liver Italian Program (CLIP) 1268 Cancer-related symptoms 1255 Candesartan 952 Candida 259 Candida albicans 1415 Candida species 612 Candidiasis 1390–1392 1566 chronic disseminated 1391 hepatosplenic 1566 Cannabinoid CB1 receptor 430 blockade 430 Cantlie's line 185 Capnography monitoring 159 Capsule endoscopy 436 Captopril 951 Caput medusa 192 CAPV See Congenital absence of the portal vein (CAPV) Carbamazepine 603 972 1440

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Carbimazole 956 Carbohydrate metabolism, disorders of 1311–1314 Carbohydrate response element–binding protein (CREBP) 1135 Carbohydrate-deficient glycoprotein (CDG) syndromes 1314 Carbohydrate-deficient transferrin (CDT) serum 887 Carbon monoxide 431 production inhibition of 430 role of, in modulating intrahepatic vascular resistance 429 Carbon tetrachloride 36 Carcinoembryogenic antigen (CEA) 103 251 1210 Carcinoembryonic antigen (CA125) 1245 Carcinogenesis 331 Carcinoid tumors 146 hepatic metastases from 143 Carcinoma 5 Cardiac chronotropic dysfunction in cirrhosis 543 Cardiac cirrhosis 1185 1192 1193 Cardiac death, donor after 1512 Cardiac disease 39 832 chronic 1186 Cardiac dysfunction 516 1185 right-sided 522 Cardiac failure 332 1219 Cardiac surgery 358 Cardiac transplantation 1195 Cardiomegaly 520 Cardiomyopathy 373 1035 ischemic dilated 1192 Cardiopulmonary disease 520 intrinsic 513 514 Cardiovascular complications 1495–1497 Cardiovascular disease (CHD) 686 1489 1495 Cardiovascular drugs 951–952 angiotensin-converting enzyme inhibitors 951 antihypertensive agents 952 β-blockers 952 calcium channel blockers 952 chlorothiazide 952 chlorthalidone 952 diuretics 952 hydralazine 952 hydrochlorothiazide 952 methyldopa 951–952 Cardiovascular risk 1496 Carnitine 371 379 Caroli's disease 175 195 1219 1241–1244 Carvedilol 450 453 Caseation 1434 Caseous necrosis with multinucleated Langhan giant cells 1435 Caspase 608 Caspase 3 activation 323 P.I-8 Caspase 8 gene expression 323 Castanospermine (CST) 1078 Catecholamines 504 Catharsis 592 Cathepsin L1 1369 Catheter angiography 1213 1217 Catheter drainage 151

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Catscratch disease 1394 Caudate lobe hypertrophy 1173 Causative agent, identification of 935 Causative drugs 941 Cavernous hemangioma 84 1172 CBD See Common bile duct (CBD) CBDL See Common bile duct ligation (CBDL) CCA See Cholangiocarcinoma (CCA) CCAAT/enhancer-binding protein (C/EBP) 1070 cccDNA See Covalently closed circular DNA (cccDNA) CCK See Cholecystokinin (CCK) receptor CD4+ cells, importance of 1402 CDC See Center for Diseases Control and Prevention (CDC) CDG syndromes See Carbohydrate-deficient glycoprotein (CDG) syndromes CDT See Carbohydrate-deficient transferrin (CDT) CEA See Carcinoembryonic antigen (CEA) C/EBP See CCAAT/enhancer-binding protein (C/EBP) Cefonicid 559 Cefotaxime 559–560 optimal dosage of 559 patient treated with 559 Ceftazidime 614 Ceftriaxone 559 649 Celecoxib 966 Celiac axis 192 Celiac disease 329 334 1141 Celiac plexus 193 Celiac sprue 334 Cell death 313 609 1139 1270 ligand–mediated 315 Cell infiltrate, periportal mononuclear 335 Cell injury 823 1129 Cell membrane, permeability of 35 Cell proliferation 1134 Cell skin cancer basal 1502 non–basal 1502 Cell swelling 313 611 Cell-mediated immunity (CMI) 1402 1406 Cellular fibronectin 400 401 Cellular homeostasis 892 Cellular immune response 816–819 Cellular infiltrates 1029 Cellular infiltration 198 Cellular injury 1135 1136–1138 Cellular macromolecules 819 Cellular phospholipids 713 Cellular rejection 1472 steroid-resistant 1476 OKT3 1476 Cellular swelling, metabolic consequences of 575 Center for Diseases Control and Prevention (CDC) 730 808 Central blood volume 545 Central circulation, mean transit time 545 Central necrosis 1208 Central nervous system (CNS) 369 569 1034 abnormalities in 574–578 drugs that act on 589–590 Central pontine myelinosis (CPM) 1484

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Central splenorenal shunt 489 Centrilobular congestion 1173 Centrilobular fibrosis 334 Centrilobular hepatocytes 41 ischemic injury to 333 Centrovenular hepatocytes 572 Cephalexin 1440 Cephalosporins, third-generation 559 Cerebellar vermis hypoplasia 1241 Cerebral edema 610–611 613–614 development of 604 611 Cerebral hyperemia 611 Cerebral perfusion pressure (CPP) 613 fall in 613 Cerebral vasoconstriction, accentuation of 548 Cerebral vasodilatation 578 Cerebrospinal fluid (CSF) 571 Ceruloplasmin 1023–1026 1031 1032 concentration of 1032 circulating copper not bound to 1032 incorporation of radioactive copper into 1033 CESD See Cholesteryl ester storage disease (CESD) Cetirizine 978 CF See Cystic fibrosis (CF) CFTR See Cystic fibrosis transmembrane conductance regulator (CFTR) Chaparral 982 Charcoal 620 Charcoal hemoperfusion 620 CHD See Cardiovascular disease (CHD) Cheilosis 372 Chelating agents 98 Chelation therapy 1024 1035–1037 British anti-Lewisite (BAL) 1024 oral 1024 Chemical chaperones 1077 Chemoembolization 1258 1273 intraoperative 1273 advantages of pretransplant 1273 Chemokines 403 814 Chemotaxis 401 reduction of 557 Chemotherapeutic agents 1273 Chemotherapy 1246 intra-arterial 191 Chenodeoxycholate 642 Chenodeoxycholic acid 29 Chest pain 519 CHF See Congenital hepatic fibrosis (CHF) Chiba needle 133 Child-Pugh class A 467 698 class B 467 698 patients 488 class C 698 cirrhosis 489 score 31 382 502 507 1267 1267 Turcotte class 698 Child-Pugh A 146 Child-Pugh's scoring system 356

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Child-Turcotte classification 31 Child-Turcotte-Pugh (CTP) 1454 Child-Turcotte-Pugh score 897 Chinese herbs, hepatotoxicity due to 607 Chlamydia 1394 Chloral hydrate 1097 Chlorambucil 689 Chlormethiazole 978 Chloroquine 1353 Chlorpromazine 973–974 1097 Chlorpropamide 1440 Cholangiocarcinoma (CCA) 135–137 142 143 146 147 165 170 306 306 669 672– 673 1191 1218 1219 1244 1245 1382 1537 detection of 103 development of 1369 1370 diagnosis of 672 intrahepatic 1207 Cholangiocytes 199 206 1380 damage of 666 Cholangiogram 159 Cholangiography 669 688 1514 1517 intraoperative 654 1517 occlusion 159 transhepatic 53 173 percutaneous 127 Cholangiohepatitis clonorchiasis, associated with 1370 oriental 1370 development of 1362 Cholangiopathy 1416 ischemic 939 Cholangioplasty 142 transhepatic 141 Cholangioscopy 161–162 Cholangitic abscess 272 282 Cholangitis 138 158 164 1244 1390 intermittent 1355 Cholate 1089 Cholate stasis 272 274 Cholecystectomy 151 167–170 192 194 338 649 651 654 656 703 1128 1416 1518 laparoscopic 141 639 654 656 1186 in pregnancy 1293 Cholecystitis 13 151 165 329 337 699 702 939 1330 1416 1567 acalculous 151 1567 acute 650 1382 calculous 705 chronic 650 Cholecystoenteric fistula 650 Cholecystography 232 Cholecystokinin (CCK) 194 705 receptor 646 Cholecystostomy, percutaneous 151 Cholecystostomy tube, removal of 151 Choledochal cysts 175 195 1236 1243–1245 1243 1293 1307–1308 clinical features of 1243–1244 course of disease 1243–1244 epidemiology of 1243–1244 etiology of 1244 management of 1244

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todani modification of the Alonso-Lej classification of 1243 treatment of 1244–1245 type III 1244 type IVa 1244 types of 1308 Choledochocele 175 1244 1245 Choledochocholedochostomy 170 stricture of 170 Choledochoduodenostomy 171 Choledochoenterostomy 170 P.I-9 Choledochojejunostomy 171 Choledocholithiasis 5 6 104–105 164–165 170 175 329 337 338 650–652 656 672 1293 common bile duct with distal acoustic shadowing 105 multiple stone in 105 stone in 104 Choledochostomy 1499 1515 Cholelithiasis 17 175 1329–1330 1567 cholesterol 649 Choleretics use of 703 Cholescintigraphy 652 Cholestasis 34 44 45 54 252 257 267 322 336 371 378 380 685 729 931 938– 939 963 1289 1379 1414 1519 acute 270–273 with acute cholangitis 271–272 diagnostic feature of 271 in adults 704 anesthetic agents, associated with 701–702 bile ductular 272 273 bland 270–271 canalicular 1564 causes of 1564 in children 704 chronic 272–278 341 366 685 intrahepatic 341 drugs 1564 drug-induced 938 clinicopathological syndromes of 937 enzymes for detection of 41–49 evaluation of 158 genetic disorders associated with 1324 intracanalicular 352 intrahepatic 338 938 1564 pathophysiology of 700 postoperative 700–702 with jaundice 1286 metronidazole, use of 704 molecular pathogenesis 1380 pathophysiology of 1380 portal tract inflammation 938 postoperative due to infection 702 sepsis 702 during pregnancy, diagnosis of 1283 1286 prolonged 1031 sickle cell intrahepatic 339 total parenteral nutrition (TPN)-induced 704 1564

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Cholestasis syndrome, familial 237 Cholestasis, benign postoperative 702–703 development of 702 diagnosis of 702 liver biopsy 702 pathogenesis of 702 Cholestasis, chronic 671 672 biochemical 668 cause of 665 in children, complications and management of 1342 management of complications 671–672 Cholestatic disease, chronic 365 1032 Cholestatic hepatitis 19 258 271 938 939 acute 259 enalapril-related 951 fibrosing 267 histopathology of 258 Cholestatic hepatotoxicity 333 Cholestatic injury 322 875 Cholestatic liver disease, chronic 665 1425 Cholestatic lpr mice 322 Cholestatic pruritus 671 Cholestatic reactions development of 702 Cholestatic syndromes differential diagnosis of 688 Cholesterol 250 351 641 644 crystallization of 644 655 hypersecretion 647 monohydrate crystals 645 saturation 647 sterol nucleus of 642 supersaturation 643 648 synthesis of 647 Cholesterol crystals 250 Cholesterol esters 290 Cholesterol gallstones 643–647 clinical risk factors for 646–647 epidemiology of 646–647 overview of factors in pathogenesis of 643–644 Cholesterol homeostasis 643 Cholesterol metabolism 333 Cholesterol microlithiasis 649 Cholesterol stone 640 Cholesteryl ester storage disease (CESD) 290 1314–1315 Cholestyramine 222 671 689 690 1106 1286 Cholic acid 29 Choline 371 379 deficiency of 365 379 supplementation of 379 Choline deficiency 1141 Choline metabolism 371 Cholinergic fibers 193 Chromatin 574 Chromatography 36 Chromosomal localization 1025 Chronic (ductopenic) rejection 276 changes of 276

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Chronic active hepatitis (CAH) 758 Chronic alcoholism 9 patients with 7 Chronic cholestasis 206 273 682 1433 1434 1439 drug-induced 278 features of 1204 of sarcoidosis 1434 Chronic cholestatic syndromes 277–278 Chronic congestive failure 209 Chronic disease 729 Chronic ductopenic rejection 1481 Chronic encephalopathy 580 patient with 580–581 Chronic gastritis 448 Chronic granulomatous disease 1441 Chronic hepatitis 38 198 209 261 265 269 273 373 926 930 952 965 1064 active 36 268 causes of 266 with cirrhosis 266 development of extinction in 210 drug-induced 940 grading activity in 269 grading and staging of 268–270 morphology of 261–267 negative 762–763 nitrofurantoin-induced 946 persistent 268 positive 762 recurrent, after liver transplantation 267 tissue remodeling in 209 treatment of 721 Chronic hepatitis B infections, ground-glass inclusions of 248 Chronic illness 1408 Chronic immunosuppression 1490 Chronic infection 807 Chronic inflammation, test for detection of 54–56 Chronic ischemic injury 295 Chronic liver disease 54 61 207 209 339 clinical and anatomic features of 205 noncirrhotic 53 pathogenesis of 207–210 vascular obstruction in 209 Chronic liver injury 953 Chronic lobular hepatitis (CLH) 758 Chronic myelogenous leukemia (CML) 352 Chronic nonsuppurative destructive cholangitis 273 Chronic pancreatitis 171 Chronic passive congestion 1193 Chronic persistent hepatitis (CPH) 758 Chronic portal-systemic encephalopathy, diagnosis of 15 Chronic rejection (CR) 1483 1538 1547 Chronic renal failure (CRF) 1490 patients with 66 Chronic systemic disorder 340 Chronic ulcerative colitis (CUC) 667 Chronicity 844 Chronicum migrans 1387 Chylomicrons 196 642 Chylous ascites 533

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CI See Cold ischemia (CI) Cidofovir 1566 Ciliated foregut cyst 301 CIN See Contrast induce nephropathy (CIN) Ciprofloxacin 609 672 944 1414 Circovirus family 606 Circulatory collapse 581 Circulatory disease, long-standing 1187 Circulatory dysfunction paracentesis-induced 551 incidence of 550 prevention of 551 pathogenesis of 529 rate of 550 spontaneous bacterial peritonitis (SBP)-induced 560 Circulatory failure 1186 liver in 1185–1195 Circulatory function deterioration in 551 553 impairment of 549 marker of 550 355 Cirrhosis 5 26 36 38 54 56 63 69 74 75 86 95 96 163 183 195 198 207 209 227 299– 300 329 331 337 341 351 352 355 365 368 370 376–378 381 382 421 424 497– 499 499 500 501 502 504 507 514 519 521 522 573 578 582 583 585 590 683 P.I-10 685 686 715 718 758 759 823 825 831 834 842– 845 867 871 873 875 880 882 890 891 902 935 938 946 1027 1029 1052 1064 1101 1117 1118 1124 –1126 1128 1129 1133– 1135 1140 1174 1185 1194 1195 1202 1217 1218 1221 1222 1230 1232 1236 1253– 1257 1267 1294 1405 1406 1433 1528 1548 accelerated fibrinolysis in 355 advanced with cholecystitis 165 patients with 548 alcohol-induced 875 alcoholic 381 904 1502 allograft 1525 antibiotic prophylaxis 562 arterial pressure 541 ascites reabsorption of 537 source of 537 with ascites diuretic approaches 547 diuretic management of, complications associated with 548 patients with 553 ascites formation in 529 pathogenesis of 544–546 biliary 408 650 cardiac dysfunction in 543–544 cardiac output, decrease in 529 causes of 396 Child-Pugh A 377 circulatory dysfunction 539–541 hypothesis of 544 mechanisms of 543 compensated 545 hepatic venous pressure, wedged 534 progression from 763

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complication of 443 cryptogenic 1117 1121 1133 causes of 17 decompensated hyponatremia 541 peripheral vascular resistance in 544 splanchnic arterial vasodilatation in 543 splanchnic circulation 545 decompensation, risk of 698 definition of 1230 dense 404 development of 198 337 1563 diagnosis of 15 299 with diuretic-resistant ascites 551 extrarenal factors 504–505 extrasplanchnic regional circulations in 541–543 factors modulating intrahepatic resistance in 427 fluid, transvascular exchange of 535–537 free water clearance 537 gastrointestinal endoscopy 435 and gastrointestinal hemorrhage 561 prophylactic antibiotics 561 glomerular filtration rate (GFR) 537 granulomas in 513 histologic progression to 832 hepatic, capillarization of sinusoids 535 hepatic hemodynamics assessment of 434–442 hepatorenal syndrome caused by 542 with and without hepatorenal syndrome cardiac index 542 mean arterial pressure 542 norepinephrine levels 542 plasma volume 542 plasma renin activity 542 histogenesis of 208 histologic features of 210 hyperdynamic circulation 540 incomplete 266 increased intrahepatic vascular resistance 426 449 infected individuals, guidelines for high-risk 836 intestinal decontamination, duration of 561 intrarenal factors 505 intrathoracic blood volume 544 liver, patients with 427 macronodular 294 299 management of paracentesis, role of 529 massive peripheral edema 533 micronodular 299 alcoholic 283 morphologic approach in 300 neutrophil leukocyte function, altered 557 nodular transformation of 1027 nonazotemic, heart rate 543 noninvasive indicator of 38 patients with 31 365 366 370 499 500 503 1142 survival of 444 patterns of 294

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peripheral vasodilatation in 453 539–541 pleural effusion 533 portal blood flow 451 portal hypertension 541 associated with 536 portal pressure, decrease in 451 prophylactic antibiotic agents 561 pulmonary complications of 493 and refractory ascites, management of 552 renal abnormalities in 503–504 504 factors for 504–505 management of 506–509 renal circulations in 541–543 renal circulatory function, impairment of 541 renal abnormalities in 498 renal dysfunction in 537–539 renal hypoperfusion in 542 reversibility of 404 sodium excretion 537 sodium retention, pathogenesis of 538 spironolactone metabolism 547 splanchnic arterial blood flow in 539 splanchnic arterial vasodilatation in 539 splanchnic circulation 540 stable 365 367 survival of different types of 894 systemic hemodynamics in 553 therapeutic maneuvers 558 treatment of 553–555 urinary tract infection 463 use of β-blockers 448 variceal bleeding in 462 vascular resistance in 428 Cirrhotic ascites ascites, differential diagnosis between 532 characteristics of 531–532 differential diagnosis of 531–534 Cirrhotic cardiomyopathy 544 Cirrhotic hydrothorax 533–534 Cirrhotic liver 703 1023 1255 1256 COX-1 pathway, overactivation of 429 endothelial dysfunction of 428–429 hepatic vascular bed of 428 Cirrhotic nodules 205 1122 Cirrhotic parenchyma 192 Cirrhotic rat livers, endothelial dysfunction 429 Cis-platinum 143 146 CK19 See Cytokeratin 19 (CK19) CLA See Conjugated linoleic acid (CLA) Clarithromycin 946 Clearance tests 30–35 Clevudine 782 course of 782 drawback of 782 CLH See Chronic lobular hepatitis (CLH) Clinical expression, diversity of 927 CLIP See Cancer of the Liver Italian Program (CLIP) Clofibrate 690 Clopidogrel 966

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Clonazepam 1097 Clonidine 450 1485 Clonorchiasis 1362 1369–1371 1370 Clonorchis 649 Clonorchis infestation 195 Clonorchis sinensis 174 1369 endoscopic cholangiography 1370 Closed needle biopsy 53 Clotting 51 369 prolongation of 354 CMI See Cell-mediated immunity (CMI) CML See Chronic myelogenous leukemia (CML) cMOAT See Canalicular multispecific organic anion transporter (cMOAT) CMV See Cytomegalovirus (CMV) CNIs See Calcineurin inhibitors (CNIs) CNS See Central nervous system (CNS) Coagulation factors decreased synthesis of 354–355 functional deficiencies of 355 Coagulative degeneration 296 Coagulative necrosis 148 254 260 1189 in ischemic injury 256 submassive zonal 262 Coagulopathy 137 355 509 522 612 615 1482 1519 1558 clinical and laboratory evaluation of 356–357 consumptive 355–359 correction in bleeding patients 357–358 laboratory evidence of 356 multifactorial basis of 356 Cocaine 977 1010 1538 Coccidioides immitis 1415 Coccidioidomycosis 1382 1393–1394 1438 P.I-11 Coffee 1255 Cognition modifiers 975–976 donepezil 975 methylphenidate 975–976 pemoline 976 tacrine (1,2,3,4-tetrahydro-9-acridinamine) 975 Colchicine 340 690 902–903 905 1089 clinical trials of 902–903 rationale for 902 Cold ischemia (CI) 321 Colectomy 1498 Colestipol 954 Collagen 874 type I 252 Collagen metabolism 1131 Collagen vascular diseases 334 hepatic manifestations of 335 Collagenase, interstitial 404 Collagens 398 fibril-forming 396 Collateral circulation 442 hepatic 192–193 portal 569 Collateral vessels development of 487 “spider-web” 100

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Coloboma 1241 Colon, inflammation of 667 Colonic bacteria 382 Colonic cleansing 592 Colonic flora 587 Colorado tick fever 1389 Colorectal cancer 1498 liver metastases of 1353 Colorectal carcinoma 147 Colorectal metastases, positron emission tomography-computed tomography scan 89 Combination therapy 782–783 1401 1405 1414 1535 Common bile duct (CBD) 158 639 649 cannulation of 159 endoscopic retrograde cholangiopancreatography of 653 endoscopic ultrasonography of 652 stones 164 Common bile duct diverticulum 1243 Common bile duct ligation (CBDL) 514 Complementary and alternative medicines (CAMs) 931 Complementary DNA (cDNA) 808 Complex acinus 201 in human 201 Complex carbohydrates 247–248 Complicated cyst 108 Compound heterozygote (C282Y/H63D) 1052 Computed tomography (CT) 64 65 127 354 583 652 890 1202 1256 1382 abdominal 1190 angiography 87 contrast-enhanced 85 high-resolution chest 515 multidetector 87 multislice 86 perfusion 88 positron emission tomography 88–91 radiation 88 Computed tomography with arterial portography (CTAP) 205 Confusional syndrome 569 Congenital absence of the portal vein (CAPV) 1307 Congenital ataxia 1241 Congenital dilatation 195 Congenital heart disease 1195 Congenital hepatic fibrosis (CHF) 195 398 1229 1236 1241–1242 1241 1309 1309 incidence of 1241 Congenital shunts 579 Congestive fibrosis, central 333 Congestive gastropathy 447 Congestive heart failure 26 39 46 1149 1231 diagnosis of 532 Congestive hepatopathy 1192 evidence of 1192 Congo red stain 252 Conjugated bile pigments, vs. unconjugated 23 Conjugated linoleic acid (CLA) 1145 Conjugation 27 Connective tissue growth factor (CTGF) 398 Connective tissue stroma 200 Consciousness 571 impairment of 580 Constrictive pericarditis 1194–1195

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Consumptive coagulopathy 355–359 Continuous ambulatory peritoneal dialysis (CAPD) 1122 Contractility 402 Contrast agents 92 types of 92 Contrast echocardiography 515 transesophageal 516 transthoracic 515 Contrast induce nephropathy (CIN) 88 Contrast-enhanced harmonic sonography (CEHS) 1204 Coombs'-positive hemolytic anemia 682 Copper, urinary excretion of 1033 Copper excretion 1023 Copper metabolism, cellular pathways of 1027 Copper stains 300 Copper storage 293 Copper toxicity 380 Copper-binding protein 275 metallothionine 248 Coprecipitants 579 Coproporphyrin 233 1089 1098 excretion in hepatobiliary diseases 1108 urinary 1106 Coproporphyrinogen oxidase 1087 1107 Core gene mutations 769 Core promoter mutations 769 Corneal pigmentation 1024 Coronary heart disease 1495 Coronary vein, transcatheter embolization of 132 Corrected sinusoidal pressure (CSP) 132 Corticosteroid therapy 875 Corticosteroids 51 408 685 871 879 895 897–900 932 945 946 965 986 1285 1442 1470– 1472 1481 1485 1493 1497 1560 and azathioprine, combina

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Copyright ©2007 Lippincott Williams & Wilkins > Back of Book > Index > D

D Dacliximab 1476 D-α-tocopheryl polyethylene glycol succinate (TPGS) 1342 Danazol 955 Dane particle 712 Danger signals 1469 Dantrolene 976 DBSP See Dibromosulphthalein (DBSP) DCD See Donors after cardiac death (DCD) DCH See Delayed cutaneous hypersensitivity (DCH) DDLTs See Deceased donor liver transplants (DDLTs) DDR2 See Discoidin domain receptor 2 (DDR2) De novo malignancy 1502–1504 risk factors for 1502 types of 1503 Deamino-8-D-arginine vasopressin (DDAVP), use of 66 Death receptors (DRs) 313 314 Death signaling cascade 323 Death-inducing signaling complex (DISC) 322 Debris, endoscopic clearance of 170 Deceased donor liver transplants (DDLTs) 1455 Dechallenge 933 Decompensation, postoperative, probability of 698 Decompressive surgery, third-therapy 1177 Decompressive surgical shunts 489 Decorin 396 Decoy receptors 316 Deep coma 580 Deep venous thrombosis (DVT) 1268 Defective biliary excretion 233 Defibrotide in sinusoidal obstruction syndrome (SOS) 1562 Deflazacort 870 Deformed mitochondria with crystalline 1138 Dehydroepiandrosterone 575 Delayed cutaneous hypersensitivity (DCH) 377 δ-aminolevulinic acid (ALA) dehydrase activity, inhibitor of 1108 intraventricular injection of 1095 production in acute intermittent porphyria (AIP) 1090

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synthase activity 1087 Delta hepatitis 707 Dementia 581 hepatic 581 Dendritic cell 718 Denver shunt 552 Deoxycholates 642 Deoxycholic acid, enterohepatic recycling of 643 Deoxymannojirimicin (DMJ) 1078 Deoxyribonucleic acid (DNA) 709 712 808 870 1066 1220 1254 1352 1533 bacterial 646 mitochondrial 883 Deranged apoptosis 866 Dermatology 75 Dermatomyositis 336 des-carboxyprothrombin 355 Descemet membrane 1029 1031 Desflurane 701 958 des-γ-carboxy prothrombin, plasma levels of 51 Desmet/Scheuer staging system 405 Desmoplasia 399 Detachable miniloops 459 nylon 459 Detoxification program 603 Devascularization procedures 491–492 492 advantage of 491 disadvantage of 491 Dextran microcarriers 623 Dextropropoxyphene 963 Diabetes 1497–1498 hepatogenous 1124 patient with 1142 Diabetes mellitus 150 329–332 1489 drugs used in, liver injury associated with 960 management of drugs used in 958–960 type 2 329 Diabetic autonomic neuropathy 332 Diacylglycerol 370 Diagnostic laparoscopy 69 complications of 71 Dialysis 66 509 peritoneal 509 Diapedesis 1354 Diarrhea 593 intractable 231 Diarrhea postcholecystectomy 654

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Diazepam 1097 Diazepam-binding inhibitor 575 Dibromosulphthalein (DBSP) 233 DIC See Disseminated intravascular coagulation (DIC) Diclofenac 542 940 965 Dideoxyinosine 843 Dietary composition 1145 Dietary lipids 370 Dietary weight loss and exercise 1145 Dieterle staining 1387 Digital clubbing 514 515 P.I-13 Diglucuronide 26 Diltiazem 952 1140 1485 Dilutional hyponatremia 504 506 spontaneous 502 Dilutional thrombocytopenia 353 Diploid cells 730 Dipyrromethane 1086 Direct thrombolytic therapy 423 Direct-guided biopsy 1390 Disaccharides, nonabsorbable 590 DISC See Death-inducing signaling complex (DISC) Discoidin domain receptor 2 (DDR2) 398 Disease, drug-induced 873–878 Disease recurrence 1150 Disease severity, scoring system for 894–895 Disofenin, Tc 99m 232 Disseminated intravascular coagulation (DIC) 353 1210 Distal renal tubular acidosis 686 Distal splenorenal shunt (DSRS) 130 423 490 multicenter randomized trial 490 Disulfiram 978 Diuretics 457 522 Divalent metal transporter 1 (DMT1) 1041 1046 Diverticulitis 702 DMJ See Deoxymannojirimicin (DMJ) DMT1 See Divalent metal transporter 1 (DMT1) DNA See Deoxyribonucleic acid (DNA) Docosahexaenoic acid (DHA) 1145 Donation after cardiac death (DCD) 1512 Donepezil 975 Donor death, cases of 620 Donor evaluation 1562 Donor organs 1150 Donor preprocurement acidosis 1482 Donor selection criteria 620

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Donors after cardiac death (DCD) 1451 Dopamine 507 Doppler echocardiography 521 transthoracic 520 Doppler flow ultrasonography 1190 Doppler imaging 1204 1215 power 85 Doppler ultrasonography 1193 1210 1482 duplex 454 Dormia-type baskets 160 Doughnut granuloma 1388 Doxorubicin 143 146 Doxycycline 1386 1388 DP See Ductal plate (DP) D-penicillamine 607 690 DPM See Ductal plate malformation (DPM) DR See Death receptors (DRs) Drug 875 administration of 592 with combined actions 453 and drug combinations 453 predictable toxins 1005 response to discontinuation of 933 Drug hypersensitivity 933 937 947 978 Drug-induced hepatitis 20 Drug ingestion, onset in relation to 932–933 repeated 933 Drug metabolism 1008 and transport, safe pathways of 1006–1009 Drug therapy, response to noninvasive evaluation of 454–455 Drug toxicity 183 335 1411 Drug-induced injury, spectrum of 876 Drug-induced liver disease 923–986 clinical features of 933 clinical suspicion of 932 clinicopathologic syndromes of 935–941 clinicopathologic classification of 934 definitions of 924–925 diagnosis of 932–935 diagnosis of exclusion 932 epidemiology of 927–930 factors contributing to, importance of 924 genetic factors for 929 age 929–930 exposure to other drugs and toxins( 930 exposure to other drugs and toxins) 930 nutritional status 930

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past history 930 sex 929–930 hepatic adaptation 935–936 histologic changes 932 importance of 926–927 management of 931–932 prevention of 930–931 risk factors for 927–930 incidence and severity of 926 928–930 specific diagnostic tests 934 terminology of 924–925 Drug-induced liver injury, categories of 1005 DSRS See Distal splenorenal shunt (DSRS) Dual-energy x-ray absorptiometry 1149 Dubin-Johnson pigment 247 249 Dubin-Johnson syndrome 27–30 54 214 227 231–235 288 1318 animal models of 233 clinical features of 231–232 frequency of 232 genetic defect 234 histopathology of 232–233 imaging studies of 232 inheritance of 234 initial descriptions of 234 laboratory findings of 232 patients with 233 phenotypic features of 232 treatment of 234 Duct strictures 195 Ductal injury, immune-mediated 1439 Ductal obstruction 222 1564 Ductal plate (DP) 189 301 1309 resorb, portions of 189 Ductal plate malformation (DPM) 301 1309 Ductopenia 273 944 964 1434 Ductopenic rejection, chronic 1482 Ducts of Luschka 167 194 Ductular proliferation 271 275 in massive hepatic necrosis 263 Ductular reaction 275 Ductules 271 at margin of portal tract 271 proliferating 303 Ductus choledochus 193 Ductus venosus 184 fissure of 185 Duodenoscope 159 173

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Duodenum 195 Duplex Doppler technique 454 Dupuytren's contractions 887 Dupuytren's hepatomegaly 698 DVT See Deep venous thrombosis (DVT) Dye tests 26 Dynamic arterial computed tomography (CT) 1259 Dysarthria 1034 Dyserythropoietic anemia 217 Dysesthesias 1093 Dysfibrinogenemia 357 Dysgeusia 7 366 Dyslipidemia 1451 1486 Dysosmia 7 Dyspepsia 650 1246 Dysplasia liver cell 300 small cell 300 301 Dysplastic cells 1254 Dysplastic nodules 205 300 1218 1229–1230 1236 and hepatocellular carcinoma (HCC) 1230 high-grade 300 low-grade 300 radiographically identified, outcome of 1231 Dyspnea 513 515 519 Dystonia 1034

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Copyright ©2007 Lippincott Williams & Wilkins > Back of Book > Index > E

E EACA See ε-aminocarproic acid (EACA) Early allograft dysfunction (EAD) 1547 Early virologic response (EVR) 841 1531 EASL See European Association for the Study of the Liver (EASL) EBA See Extrahepatic biliary atresia (EBA) Ebrotidine 978 EBV See Epstein-Barr virus (EBV) Ecchymosis 9 ECE See Endothelin-converting enzyme (ECE) Echinococcal cysts 101 1229 1245–1246 diagnosis of 1246 Echinococcosis 174 1362 1371–1373 Echinococcus granulosus 174 1229 1245 1371 cysts, surgical therapy for 1372 Echinococcus multilocularis 174 1229 1246 1371 Echinococcus tapeworms 1359 Echinococcus vogeli 1371 Echinocytes 349 350 Echocardiography 516 Echogenicity 93 Eck fistula procedure 489 Eclampsia 1287 ECM See Extracellular matrix (ECM) ECMO See Extracorporeal membrane oxygenation (ECMO) Ectasia 1208 Edema 375 497–499 700 1149 peripheral 533–534 of skin 1103 Edematous myxoid stroma 1220 P.I-14 EDTA See Ethylenediaminetetraacetic acid (EDTA) EEG See Electroencephalogram (EEG) Efavirenz 950 951 Efflux transporters canalicular 1007 in hepatocyte 1007 EHL See Electric hydraulic lithotripsy (EHL) Ehrlichia chaffeensis 1388

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Ehrlichiosis 1388 involvement of liver 1388 EIA See Enzyme immunoassay (EIA) Eicosanoids 505 Eicosapentaenoic acid (EPA) 1145 ELAD See Extracorporeal liver assist device (ELAD) Elastase inhibitor 1068 Elastosis perforans serpiginosa 1036 cheloid-like lesions of 1036 Electric hydraulic lithotripsy (EHL) 160 Electrocardiographic abnormalities 520 Electroencephalogram (EEG) 582 Electroencephalographic monitor 611 Electrolyte imbalance 1484 Electrolytes 591 Electron microscopy 251–252 808 936 Electron probe analysis 252 Electron transport chain (ETC), mitochondrial, impaired function of 1138 Electrophoresis 36 44 cellulose acetate 49 on cellulose acetate 44 ELISA See Enzyme-linked immunosorbent assay (ELISA) ELTR See European Liver Transplant Registry (ELTR) Embolic agents 143 Embolization therapy 65 Embolotherapy 143–148 Embryogenesis 196 Emerging drugs 979–980 alfuzosin 979 bosentan 979–980 imatinib mesylate 980 liver injury associated with 979 orlistat 980 EMH See Extramedullary hematopoiesis (EMH) Emperipolesis 264 Emphysema 1066 1068 1078 pulmonary 1063 1065 Emtricitabine 717 781 1403 Enalapril 951 Encapsulated hepatocytes, transplantation of 626 Encephalopathy 143 365 370 422 485 489 585 588 589 610 1255 acute episode of 580 chronic 589 593 diuretic-induced 591 hepatic 15 183 365 369 381–382 501 patients with 15

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low-grade 582 nontransplantation, survival of 603 postshunt 594 progression of 603 End of treatment response (ETR) 1530 End-stage renal disease (ESRD) 1504 Endocannabinoids 430 Endocrine disorders 329–334 drugs used in treatment of 954–956 Endogenous hepatic glucose, insulin-mediated suppression of 370 Endoglin (ENG) 1179 Endophlebitis central vein 261 fibro-obliterative 1173 Endoplasmic reticulum (ER) 316–317 322 1063 1065 degradation of 1074 Endoplasmic reticulum (ER) stress 314 316 Endoscopic ablation by argon plasma 475 Endoscopic banding ligation 458–459 Endoscopic biliary stent, placement of 1191 Endoscopic gauge, pressure-sensitive 454 Endoscopic injection sclerotherapy 458 459 470 Endoscopic pressure gauge 441 Endoscopic pressure-sensitive gauges 440 Endoscopic retrograde cholangiogram, postcholecystectomy 159 Endoscopic retrograde cholangiopancreatography (ERCP) 16 17 65 102 157–175 161 652 665 688 1240 1416 1499 advantages of 157 balloon extraction 167 complications of 162–164 grading system for 163 contradictions of 158 indications for 157–158 154 jaundice, postoperative 699 in neonates and children, indications for 174–175 patients with, severe reaction 158 pediatric 174 post cholangitis 159 pancreatitis 162 during pregnancy 158 preparation of 159 role of 158 in choledocholithiasis 165 techniques of 159–162 therapeutic 159–161 Endoscopic retrograde pancreatography 1485

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biliary indications for 175 Endoscopic sclerotherapy 490 558 Endoscopic sphincterotomy (ES) 160 complications of 164 grading system for 163 Endoscopic therapy 158 166 169 173 458–461 486 Endoscopic treatment 459 Endoscopic ultrasonography (EUS) 16 652 Endoscopic variceal sclerotherapy (EVS) 448 nonselective β-blockers, randomized clinical trials 469 randomized clinical trials 460 with vasoactive drugs, randomized clinical trials 465 466 Endoscopists 168 Endoscopy 65 127 133 435–436 capsule 436 Endosonography 442 Endothelial cell injury 198 Endothelial cells 196–198 397 399 400 sinusoidal 196 400 Endothelial dysfunction 428 Endothelial nitric oxide synthase (eNOS) 429 hepatic, decreased activity of 429 Endothelins (ETs) 427 542 blockade of 451 blockers 451 507 receptors ET-A 427 ET-B 427 role of 428 Endothelin-1, upregulation of 620 Endothelin-converting enzyme (ECE) 402 Endotoxemia 430 589 979 1380 acute 402 Endotoxin 365 379 1354 Energy abnormalities 577 Energy expenditure 365 367 Energy intake 366 Energy, metabolism of 366–367 Energy vitalizers 982 Enflurane 701 eNOS See Endothelial nitric oxide synthase (eNOS) Entacapone 976 Entamoeba dispar 1352 Entamoeba histolytica 1351 1359 1416 genome, sequencing of 1352 genotyping of 1352 Entecavir 717 770 780–781 784 1534

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adverse events of 781 dose regimen 781 resistance 781 response durability of 781 predictors of 781 Enteral nutrition 615 Enteral tube feeding 381 Enteric fever 1381 Enterocytes 1041 1070 Enterocytozoon bieneusi 174 Enterohepatic recirculation 1026 Enteroviruses 604 1327 Enucleation 1210 1214 1217 Enzyme defects 1089–1090 in acute intermittent porphyria (AIP) 1091 molecular pathogenesis of 1090–1092 Enzyme immunoassay (EIA) 819 1353 Enzyme-linked immunosorbent assay (ELISA) 682 1334 1362 1384 1437 Eosinophilia 701 943 1362 1371 1393 Eosinophils 261 EPA See Eicosapentaenoic acid (EPA) Epigastrium 10 Epileptiform activity 611 Epinephrine 613 1538 Epistaxis 1179 Epithelioid cells 1426 Epithelioid granulomas 273 1361 1364 1426 1438 1439 distinctive type of 1429 Epivir-hepatitis B virus 775–778 Epoxides 1010 EPP See Erythropoietic protoporphyria (EPP) Epping jaundice 939 ε-aminocarproic acid (EACA) 357 Epstein-Barr virus (EBV) 257 604 702 723 1326 1412 1565 ER See Endoplasmic reticulum (ER) ERCP See Endoscopic retrograde cholangiopancreatography (ERCP) P.I-15 Erlich's reagent 1094 Erosion theory 432 Erythema 1103 Erythrocyte protoporphyrin 1107 Erythrocytes 216 370 Erythromycin 41 1417 Erythrophagocytosis 352 Erythropoiesis

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disorders of 1054 excessive ineffective 226 ineffective 216 222 343 Erythropoietic porphyria, congenital 1106–1107 Erythropoietic protoporphyria (EPP) 1103 ALA synthase activity 1103 biochemical evaluation of 1103 clinical manifestation in 1103 hepatobiliary disease in 1105 with liver disease 1105 prognosis of 1105 liver transplantation in 1106 management of 1106 mouse model of 1105 photosensitivity in 1103–1105 Erythropoietin 840 1409 ES See Endoscopic sphincterotomy (ES) Escherichia coli 556 Esophageal band ligation 458 Esophageal sphincter 454 Esophageal stenosis 458 Esophageal ulcers 458 Esophageal variceal hemorrhage 365 Esophageal varices 436 440 689 acute bleeding from 446 antibiotics 463 balloon tamponade 466–467 replacement of blood volume 462 complications 462 endoscopic and pharmacologic therapy, combined 466 general management 461 surgery 467 treatment of 461–462 endoscopic 465–466 pharmacologic 463–465 development of 443 emergency banding ligation 465 endoscopic band ligation of β-blockers 460 randomized clinical trials 471 endoscopic injection sclerotherapy 470 endoscopic obturation of 466 first bleeding incidence of 444–445 prevention of 456–458 risk, assessment of 445 gastrointestinal bleeding 446

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incidence of 443 management of 342 pressure of 441 progression of 443–444 recurrent bleeding from β-blockers, organic nitrates 468–471 banding ligation, sclerotherapy 471 endoscopic treatment 470–471 long-term 446 pharmacologic treatment 468–471 prevention of 468–474 ruptured 446 screening for 445 Esophageal wall necrosis 458 Esophagitis 1290 1291 Esophagogastroduodenoscopy 18 Esophagoscope 486 ESRD See End-stage renal disease (ESRD) Essential thrombocythemia (ET) 352 Estradiol benzoate 231 Estrogen blockade with tamoxifen 1260 Estrogen-receptor antagonists 956 Estrogens 647 ESWL See Extracorporeal shock wave lithotripsy (ESWL) ET See Essential thrombocythemia (ET) Etanercept 900–901 Ethambutol 946 1383 Ethanol 1013–1014 and acetaminophen 1013–1014 Ethanol ablation 148 Ethanol conundrum 1123–1124 Ethanol toxicity 317 Ethionamide 946 Ethylenediaminetetraacetic acid (EDTA) 354 ETR See End of treatment response (ETR) Etretinate 986 ETs See Endothelins (ETs) EURALT See European Auxiliary Liver Transplant (EURALT) European Association for the Study of the Liver (EASL) 1256 European Auxiliary Liver Transplant (EURALT) 619 European Liver Transplant Registry (ELTR) 619 EUS See Endoscopic ultrasonography (EUS) EVR See Early virologic response (EVR) Excoriations 681 Excretion rate 32 Explosion hypothesis 432

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Explosion theory 433 Extended criteria donor (ECD) grafts, use of 1547 Extracellular matrix (ECM) 395 degradation of 399–400 Extracellular signal–regulated kinases 1 and 2 (ERK1/2) 1139 Extracorporeal liver assist device (ELAD) 624 extracorporeal perfusion with 625 Extracorporeal liver support 620–625 categorization of 620 Extracorporeal membrane oxygenation (ECMO) 1334 Extracorporeal shock wave lithotripsy (ESWL) 655 Extrahepatic biliary atresia (EBA) 1308 1329 1330 Extrahepatic biliary obstruction 688 Extrahepatic collaterals 192 Extrahepatic sarcoidosis 1442 Extramedullary hematopoiesis (EMH) 352 1219 Extrarenal sorbitol clearance 439 Eye tissues 370

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Copyright ©2007 Lippincott Williams & Wilkins > Back of Book > Index > F

F F 2 -isoprostanes 505 Factor V Leiden mutation 1172 FAH See Fumarylacetoacetate hydrolase (FAH) Falciform ligament 185 187 Famciclovir 778 1403 1563 Familial amyloid polyneuropathy (FAP) 339 1459 Familial hyperbilirubinemia 228–237 conjugated 231–237 unconjugated 228 principal features of 229 spectrum of 228 Familial intrahepatic cholestasis 228 1334 Fanconi's anemia 955 Fanconi's syndrome 779 782 1316 FAO See Fatty acid oxidation (FAO) FAP See Familial amyloid polyneuropathy (FAP) Farnesoid X receptor (FXR) 402 643 Fas 315 316 activation of 316 disruption of 323 messenger RNA (mRNA) 322 significance of 316 Fas ligand (FasL) 315 316 323 1470 Fas receptor 322 hepatic 320 importance of 322 signaling 315 Fasciola 1369 Fasciola hepatica 174 1368–1369 Fascioliasis 1362 1368–1369 acute 1368 atypical manifestations of 1369 antihelminthic compound for 1369 chronic 1369 biliary symptoms in 1369 human 1368 FasL See Fas ligand (FasL) Fat 249–250

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Fatal hepatotoxicity 876 Fatal liver failure 947 Fatigue 333 372 681 688 830 Fatty acid oxidation (FAO), disorders of 1318–1319 Fatty acyl CoA 370 Fatty infiltration 1125 1129 Fatty liver 938 computed tomographic scan 94 detection by imaging 93–94 impact of 95–96 Fatty liver disease 99 1121 1134 FDA See Food and Drug Administration (FDA) FDG See 2-fluoro-deoxy-d-glucose (FDG) Feathery degeneration 272 Fecal nitrogen excretion 382 Felbamate 973 Felty's syndrome 1232 Female hormone replacement therapy 1237 Fentanyl 159 Fenton reactions 322 Ferritin 1041 1049 Ferrochelatase 1087 Ferroportin 1041 1046 Ferroportin mutations inactivating 1048 types of 1048 Fetor hepaticus 580 Fetus, risk for 1288 Fever of unknown origin (FUO) 1425 1430 FFP See Fresh frozen plasma (FFP) FHF See Fulminant hepatic failure (FHF) P.I-16 FHVP See Free hepatic venous pressure(FHVP) Fialuridine (FIAU) 1011 Fibrates 954 1150 Fibrin 627 Fibrin-ring granulomas 1429 Fibrinogen 369 Fibrinogen storage disease 290 304 Fibrinoid necrosis 1433 Fibrinoid nodules 1433 Fibrinolysis 1547 accelerated 355 Fibroblasts 372 730 hepatic 200 Fibrocystic disease 1236–1245 1237 congenital 195

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Fibrocytes 1429 “Fibrofatty pattern” 93 Fibrogenesis 401–402 875 880 892 894 908 941 stimulation of 402 Fibrogenic cells 406 Fibrolamellar 304 Fibrolamellar carcinoma 110 1204 1222 Fibromodulin 396 Fibronectin 556 Fibropolycystic diseases 300–302 FibroScan 71 406 Fibrosing alveolitis 513 409 causes of 396 chicken-wire 281 concentric intimal 519 and connective tissue 246–247 hepatic 395 401 402 1364–1365 histologic findings of 75 in liver allograft, percentage of patients with 1462 noninvasive markers of 61 pericellular 281 378 peripheral 1438 portal 1367 progression of 403–404 accurate prediction of 405 assessment of 405 progressive 1147 reduced 408 reversal of 1365 reversibility of 403–404 sinusoidal 1193 symmers 1365 Fibrospect 406 FibroTest 20 53 71 72 406 Fibrotic liver 396 extracellular matrix (ECM), cellular sources of 398–399 Fibrous connective tissue 1218 Fibrous sheath 185 Fick's principle 440 Fine-needle biopsy, sensitivity of 75 Fissures 184 Fitz-Hugh-Curtis syndrome 1394 Flaviviridae 606 837 Flaviviruses 809 Fleeting skin lesions 6 Florid duct lesion 273 274 FLR See Future liver remnant (FLR)

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Flucloxacillin 614 Fluconazole 948 1361 Fluid wave 14 Flumazenil 576 588 592 Fluorescence intensity 822 Fluorescent treponemal antibody (FTA) 1386 2-fluoro-deoxy-d-glucose (FDG) 88 Fluoroquinolone 1016 long-term 1381 FNH See Focal nodular hyperplasia (FNH) Focal fat deposition 96 Focal fat infiltration 96 Focal fat sparing 96 areas affected by 96 Focal fatty change 1220 treatment of 1220 Focal fatty liver, ultrasound scan 96 Focal fatty sparing, ultrasound image 96 Focal hepatic candidiasis 1391 1392 Focal hepatic necrosis 937 Focal liver lesions, fine-needle aspiration of 61 Focal necrosis 254 260 352 perivenular 260 Focal nodular hyperplasia (FNH) 109– 111 111 205 302 941 1201 1202 1203 1205 1229 1233– 1235 1296 1335 cause of 1233 clinical manifestations of 1204 composed of 110 diagnosis of 109 1207 1235 differential diagnosis of 1207 epidemiology of 1202 and hepatic hemangioma 1206 imaging studies 1204–1207 management of 1208 natural history 1204 pathogenesis of 1202–1203 pathology of 1203–1204 prognosis of patients with 1204 resected, macroscopic appearance of 1234 telangiectatic 1204 unusual forms of 1235 Focal solid lesion, clinical approach to 1221–1222 Focal sparing 1121–1122 Focal steatosis 1121–1122 Food and Drug Administration (FDA) 85 688 837 1403 Foregut, hepatic diverticulum of 187

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Foscarnet 1566 Fosinopril 951 Fractalkine 686 Fractures 1494 Francisella tularensis 1381 Free fatty acids (FFAs) 370 Free hepatic venous pressure(FHVP) 424 measurements of 437 Fresh frozen plasma (FFP) 357 1268 Friction rub hepatic, causes of 13 peritoneal 13 transient 13 Friedreich's ataxia 972 FTA See Fluorescent treponemal antibody (FTA) Fulminant fibrosis 404 Fulminant hepatic failure (FHF) 314 323 601– 627 730 1292 1460 1562 1565 due to acetaminophen hepatotoxicity 603 acetaminophen-induced, patients with 618 acetaminophen-related 603 cause of 618 due to food, contaminated 606 due to HBV 605 cerebral edema 611 children with 606 clinical implications of 602–607 clinical syndrome pathophysiology of 610–612 severity of 602 coagulopathy, associated with 612 complications of 606 definitions of 602 602 development of 604 605 608 encephalopathy in 610 energy requirements in 612 etiology of 602–607 etiology-specific therapies 602 HBV-related 619 HBV strain, association between 605 hemodynamic changes 610 hepatic encephalopathy in 611 hepatitis C virus (HCV) 605 hepatitis virus 604–606 hepatocellular regeneration in 609 hepatocyte injury, molecular mechanisms of 608–609 hepatocyte necrosis in 607

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hepatocyte transplantation in 627 induction of 625 ischemic 607 non–A to E 606 nonacetaminophen-related clichy criteria 617 king's College criteria 617 outcomes of 611 oxygen consumption 610 pathogenesis of 607 plasmapheresis, large-volume 620 renal replacement therapy 614 risk of 606 hepatitis A virus (HAV) 604 supplementation in 609 supportive management 612–615 survival of 602 620 tissue oxygen extraction 610 transplantation for 618 mortality rate 619 outcome of 619 survival is 619 trends in 618 viral-related cases of 619 Fulminant hepatitis 1035 Fulminant hepatitis B, transplantation for 609 Fumarylacetoacetate hydrolase (FAH) 1315 Fungal abscesses 1567 Fungal infections 1389–1394 1415–1416 1566–1567 susceptibility to 612 Fungi 285 FUO See Fever of unknown origin (FUO) Furosemide 546 administration of 547 and spironolactone P.I-17 administration of 547 comparison of 547 Future liver remnant (FLR) 150 FXR See Farnesoid X receptor (FXR)

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F F 2 -isoprostanes 505 Factor V Leiden mutation 1172 FAH See Fumarylacetoacetate hydrolase (FAH) Falciform ligament 185 187 Famciclovir 778 1403 1563 Familial amyloid polyneuropathy (FAP) 339 1459 Familial hyperbilirubinemia 228–237 conjugated 231–237 unconjugated 228 principal features of 229 spectrum of 228 Familial intrahepatic cholestasis 228 1334 Fanconi's anemia 955 Fanconi's syndrome 779 782 1316 FAO See Fatty acid oxidation (FAO) FAP See Familial amyloid polyneuropathy (FAP) Farnesoid X receptor (FXR) 402 643 Fas 315 316 activation of 316 disruption of 323 messenger RNA (mRNA) 322 significance of 316 Fas ligand (FasL) 315 316 323 1470 Fas receptor 322 hepatic 320 importance of 322 signaling 315 Fasciola 1369 Fasciola hepatica 174 1368–1369 Fascioliasis 1362 1368–1369 acute 1368 atypical manifestations of 1369 antihelminthic compound for 1369 chronic 1369 biliary symptoms in 1369 human 1368 FasL See Fas ligand (FasL) Fat 249–250

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Fatal hepatotoxicity 876 Fatal liver failure 947 Fatigue 333 372 681 688 830 Fatty acid oxidation (FAO), disorders of 1318–1319 Fatty acyl CoA 370 Fatty infiltration 1125 1129 Fatty liver 938 computed tomographic scan 94 detection by imaging 93–94 impact of 95–96 Fatty liver disease 99 1121 1134 FDA See Food and Drug Administration (FDA) FDG See 2-fluoro-deoxy-d-glucose (FDG) Feathery degeneration 272 Fecal nitrogen excretion 382 Felbamate 973 Felty's syndrome 1232 Female hormone replacement therapy 1237 Fentanyl 159 Fenton reactions 322 Ferritin 1041 1049 Ferrochelatase 1087 Ferroportin 1041 1046 Ferroportin mutations inactivating 1048 types of 1048 Fetor hepaticus 580 Fetus, risk for 1288 Fever of unknown origin (FUO) 1425 1430 FFP See Fresh frozen plasma (FFP) FHF See Fulminant hepatic failure (FHF) P.I-16 FHVP See Free hepatic venous pressure(FHVP) Fialuridine (FIAU) 1011 Fibrates 954 1150 Fibrin 627 Fibrin-ring granulomas 1429 Fibrinogen 369 Fibrinogen storage disease 290 304 Fibrinoid necrosis 1433 Fibrinoid nodules 1433 Fibrinolysis 1547 accelerated 355 Fibroblasts 372 730 hepatic 200 Fibrocystic disease 1236–1245 1237 congenital 195

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Fibrocytes 1429 “Fibrofatty pattern” 93 Fibrogenesis 401–402 875 880 892 894 908 941 stimulation of 402 Fibrogenic cells 406 Fibrolamellar 304 Fibrolamellar carcinoma 110 1204 1222 Fibromodulin 396 Fibronectin 556 Fibropolycystic diseases 300–302 FibroScan 71 406 Fibrosing alveolitis 513 409 causes of 396 chicken-wire 281 concentric intimal 519 and connective tissue 246–247 hepatic 395 401 402 1364–1365 histologic findings of 75 in liver allograft, percentage of patients with 1462 noninvasive markers of 61 pericellular 281 378 peripheral 1438 portal 1367 progression of 403–404 accurate prediction of 405 assessment of 405 progressive 1147 reduced 408 reversal of 1365 reversibility of 403–404 sinusoidal 1193 symmers 1365 Fibrospect 406 FibroTest 20 53 71 72 406 Fibrotic liver 396 extracellular matrix (ECM), cellular sources of 398–399 Fibrous connective tissue 1218 Fibrous sheath 185 Fick's principle 440 Fine-needle biopsy, sensitivity of 75 Fissures 184 Fitz-Hugh-Curtis syndrome 1394 Flaviviridae 606 837 Flaviviruses 809 Fleeting skin lesions 6 Florid duct lesion 273 274 FLR See Future liver remnant (FLR)

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Flucloxacillin 614 Fluconazole 948 1361 Fluid wave 14 Flumazenil 576 588 592 Fluorescence intensity 822 Fluorescent treponemal antibody (FTA) 1386 2-fluoro-deoxy-d-glucose (FDG) 88 Fluoroquinolone 1016 long-term 1381 FNH See Focal nodular hyperplasia (FNH) Focal fat deposition 96 Focal fat infiltration 96 Focal fat sparing 96 areas affected by 96 Focal fatty change 1220 treatment of 1220 Focal fatty liver, ultrasound scan 96 Focal fatty sparing, ultrasound image 96 Focal hepatic candidiasis 1391 1392 Focal hepatic necrosis 937 Focal liver lesions, fine-needle aspiration of 61 Focal necrosis 254 260 352 perivenular 260 Focal nodular hyperplasia (FNH) 109– 111 111 205 302 941 1201 1202 1203 1205 1229 1233– 1235 1296 1335 cause of 1233 clinical manifestations of 1204 composed of 110 diagnosis of 109 1207 1235 differential diagnosis of 1207 epidemiology of 1202 and hepatic hemangioma 1206 imaging studies 1204–1207 management of 1208 natural history 1204 pathogenesis of 1202–1203 pathology of 1203–1204 prognosis of patients with 1204 resected, macroscopic appearance of 1234 telangiectatic 1204 unusual forms of 1235 Focal solid lesion, clinical approach to 1221–1222 Focal sparing 1121–1122 Focal steatosis 1121–1122 Food and Drug Administration (FDA) 85 688 837 1403 Foregut, hepatic diverticulum of 187

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Foscarnet 1566 Fosinopril 951 Fractalkine 686 Fractures 1494 Francisella tularensis 1381 Free fatty acids (FFAs) 370 Free hepatic venous pressure(FHVP) 424 measurements of 437 Fresh frozen plasma (FFP) 357 1268 Friction rub hepatic, causes of 13 peritoneal 13 transient 13 Friedreich's ataxia 972 FTA See Fluorescent treponemal antibody (FTA) Fulminant fibrosis 404 Fulminant hepatic failure (FHF) 314 323 601– 627 730 1292 1460 1562 1565 due to acetaminophen hepatotoxicity 603 acetaminophen-induced, patients with 618 acetaminophen-related 603 cause of 618 due to food, contaminated 606 due to HBV 605 cerebral edema 611 children with 606 clinical implications of 602–607 clinical syndrome pathophysiology of 610–612 severity of 602 coagulopathy, associated with 612 complications of 606 definitions of 602 602 development of 604 605 608 encephalopathy in 610 energy requirements in 612 etiology of 602–607 etiology-specific therapies 602 HBV-related 619 HBV strain, association between 605 hemodynamic changes 610 hepatic encephalopathy in 611 hepatitis C virus (HCV) 605 hepatitis virus 604–606 hepatocellular regeneration in 609 hepatocyte injury, molecular mechanisms of 608–609 hepatocyte necrosis in 607

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hepatocyte transplantation in 627 induction of 625 ischemic 607 non–A to E 606 nonacetaminophen-related clichy criteria 617 king's College criteria 617 outcomes of 611 oxygen consumption 610 pathogenesis of 607 plasmapheresis, large-volume 620 renal replacement therapy 614 risk of 606 hepatitis A virus (HAV) 604 supplementation in 609 supportive management 612–615 survival of 602 620 tissue oxygen extraction 610 transplantation for 618 mortality rate 619 outcome of 619 survival is 619 trends in 618 viral-related cases of 619 Fulminant hepatitis 1035 Fulminant hepatitis B, transplantation for 609 Fumarylacetoacetate hydrolase (FAH) 1315 Fungal abscesses 1567 Fungal infections 1389–1394 1415–1416 1566–1567 susceptibility to 612 Fungi 285 FUO See Fever of unknown origin (FUO) Furosemide 546 administration of 547 and spironolactone P.I-17 administration of 547 comparison of 547 Future liver remnant (FLR) 150 FXR See Farnesoid X receptor (FXR)

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H H63D mutation in hemochromatosis gene (HFE) 1044–1045 HA See Hepatic arteries (HA) HAART See Highly active antiretroviral therapy (HAART) Haber-Weiss reactions 322 Hairy cell leukemia (HCL) 1441 Hall's stain 249 270 Halothane 701 Halothane hepatitis 956 957 Hamartomas 306 Harderoporphyria 1107 Harris-Benedict equation 367 Hartmann's pouch 194 Hashimoto's thyroiditis 685 HAT See Hepatic artery thrombosis (HAT) HAV See Hepatitis A virus (HAV) HBcAg See Hepatitis B core antigen (HBcAg) HbeAg See Hepatitis B e antigen (HbeAg) HBIG See Hepatitis B immunoglobulin (HBIG) HBsAg See Hepatitis B surface antigen (HBsAg) HBV See Hepatitis B virus (HBV) HBV X protein (Hbx) 321 765 HBx See HBV X protein (Hbx) HCC See Hepatocellular carcinoma (HCC) HCIG See Hepatitis C immunoglobulin (HCIG) HCL See Hairy cell leukemia (HCL) HCV See Hepatitis C virus (HCV) HCV infection See Hepatitis C virus (HCV) infection HD See Hodgkin's disease (HD) HDACs See Histone deacetylases (HDACs) HDL See High-density lipoprotein (HDL) HDV See Hepatitis D virus (HDV) Health care environment 747–748 Health care workers 748 Health-related quality of life (HRQOL) 1453 1455 1490 Heart disease 426 Heat denaturation 44 Heatstroke 607 and liver 1191

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P.I-19 Helicobacter pylori 447 593 infection with 1285 HELLP syndrome See Hemolysis elevated liver enzymes and low platelet count (HELLP) syndrome Hemangioendothelioma epithelioid 307 308 infantile 307 type II, differentiation of 1219 Hemangioma 84 92 307–308 307 1201 1202 1208– 1214 1209 1233 1296 cavernous 1208 clinical manifestations of 1209–1210 complications of 1210 diagnosis of 1213 epidemiology of 1208 giant 109 1209 peripheral nodular enhancement 110 spin-echo magnetic resonance image 110 hepatic 1202 1208 1211 1212 1213 spontaneous rupture of 1210 hyperechoic lesion 109 imaging studies of 1210–1213 management of 1213–1214 natural history of 1210 nonspecific hypodense lesion 109 pathogenesis of 1208–1209 pathology of 1209 peripheral nodular enhancement characteristics 109 preexisting 955 Hematin 1096 intravenous administration of 1107 in lead poisoning 1108 Hematin therapy, complication of 1096 Hematobilia 137 Hematologic disorders and liver 349–359 Hematologic malignancy 66 Hematoma 704 1288 management of 1289 hepatic, and rupture 1289 Hematopoiesis, extramedullary 343 378 Hematopoietic cell transplantation (HCT) “Achilles' heel” of 1557 biliary complications 1567 drugs 1564 evaluation of donor and recipient in 1558 fungal infections 1566–1567

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risk factors for 1566 hepatobiliary complications in 1557–1567 liver disease causes of 1557 1559 liver biopsy 1558 prevalence of 1557–1558 prognostic indicators of 1558–1559 sinusoidal obstruction syndrome (SOS), risk factors for 1561 Hematopoietic cells 189 353 sinusoidal 189 Hematoporphyrin derivatives, use of 173 Hematuria 1035 Heme 1086 1088 biliary excretion of 1089 to bilirubin, pathway for the degradation of 215 bilirubin production from 214–215 biosynthesis of 1086–1087 control of 1088 hepatic 1087–1089 porphyrin ring of 214 production of 1086 Heme biosynthesis, disorders of 217 Heme biosynthetic pathway 1085 1088 Heme metabolism 1086–1087 Heme oxidation 430 enzymes HO-1 430 HO-2 430 Heme oxygenase (HO) 429 microsomal 1089 Heme oxygenase-1 (HO-1) 514 Heme oxygenase/biliverdin reductase pathway, cytoprotective effects of 215–216 Hemithorax, right 62 Hemobilia 64 70 166–167 cause of 166 ultrasonographic findings 167 Hemochromatosis 18 98 118 138 204 266 293 322 1041– 1055 1202 1230 genetic 293–295 history of 1042 micronodular cirrhosis of 294 Hemochromatosis gene (HFE) 1041 expression 1044 in mice, experimental disruption of 1045 mutations, prevalence of 1053 patients with porphyria cutanea tarda (PCT) 1054

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protein 1044–1045 structure of 1044 Hemochromatosis gene (HFE) mutation 1045 cysteine to tyrosine at amino acid 282 (C282Y) 1041 1042 1044– 1045 histidine to aspartate at amino acid 62 (H62D) 1041 1044 1045 Hemodiadsorption systems 620 Hemodialysis 509 620 717 720 828 1237 Hemodialysis patients 748 Hemodynamic, moderate, induction of 614 Hemodynamic stability 613 Hemoglobin 214 217 homozygous 351 reticuloendothelial system of, degradation in 213 Hemoglobin protoporphyrin 216 Hemoglobinuria 350 Hemojuvelin (HJV) gene 1041 1048 Hemolysis 41 222 226 338 354 607 841 1031 1288–1289 chronic 349 laboratory signs of 350 Hemolysis elevated liver enzymes and low platelet count (HELLP) syndrome 607 clinical presentation of 1288 Hemolytic anemia 1409 chronic 648 extrinsic nonimmune 349 350 nonimmunopathic 1034 Hemoperfusion 620 charcoal 620 Hemophilia 358 828 Hemophiliacs 66 Hemoprotein 1086 pool 1088 Hemorrhage 192 1203 1208 intracranial 356 intraperitoneal 64 131 137 parenchymal 200 prevention in cirrhosis 1294 Hemorrhagic risk 437 Hemorrhagic telangiectasia, hereditary 1233 Hemosiderin 98 204 270 288 Hemosiderin accumulation 293 Hemosiderin pigment 293 Hemosiderin stains 289 Hemosiderinuria 350 Hemosiderosis 293 335 352 1100 Hemothorax 65

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Hepar lobatum 1386 1387 Heparins, low-molecular-weight 953 Hepatectomy 53 1271 1512 native 1512 abdominal cavity after 1513 partial 1076 regeneration after 609 right 1521 Hepatic abscesses 46 Hepatic acinus 1186 Hepatic acute-phase reactant, positive 1070 Hepatic adenoma 111 205 941 1208 1296 Hepatic amyloidosis 340 Hepatic arterial flow, regulation of 439 Hepatic arterial stenoses 138 Hepatic arteriography 128–129 1205 catheter-based 128 Hepatic arteries (HA) 135 143 185 191–192 487 1186 1191 anomalies of 191 catheterization of 145 computed tomography (CT) 87 ligation of 192 occlusion of 1185 spectral doppler tracing of 85 superselective catheterization, digital angiogram of 128 Hepatic artery ligation 1214 Hepatic artery obstruction 1260 Hepatic artery thrombosis (HAT) 409 1342 1481 1482 1521 1529 1546– 1547 Hepatic abnormalities, associated with various thyroid 332 Hepatic bilirubin, production of 19 Hepatic blood flow anatomy of 1186–1187 measurement of 439 physiology of 1186–1187 Hepatic blood vessels, Doppler imaging 85 Hepatic congestion, early relief of 1177 Hepatic cyst 84 101–102 computed tomography (CT) 101 magnetic resonance imaging (MRI) 101–102 ultrasonography 101 ultrasound image 102 Hepatic damage 721 Hepatic decompensation 834 Hepatic disease 1352 1392 Hepatic diverticulum 189 Hepatic drug reactions 925–926 927

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Hepatic duct 159 195 Hepatic dysfunction 19 24 26 28 29 34 207 329

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Copyright ©2007 Lippincott Williams & Wilkins > Back of Book > Index > I

I IASL See International Association for the Study of the Liver (IASL) Iatrogenic strictures 171 IBD See Inflammatory bowel disease (IBD) Ibuprofen 503 542 964 ICAM See Intracellular cell adhesion molecule (ICAM) ICC See Indian childhood cirrhosis (ICC) ICDH See Isocitrate dehydrogenase (ICDH) ICG See Indocyanine green (ICG) Icterus 5 ICU See Intensive care unit (ICU) Ideal fibrosis marker 405 Idiopathic adulthood ductopenia 278 688 Idiopathic granulomatous hepatitis 1442 Idiopathic neonatal hepatitis 258 with giant cell transformation 259 Idiosyncrasy 877 Idiosyncratic drug 925 Idiosyncratic hepatotoxicity 1006 1016 acquired immune mechanisms 1015 Idiosyncratic toxicity 1005 1014 IFN-α See Interferon α (IFN-α) IFN-γ See Interferon-γ (IFN-γ) IFN-induced protein 718 IFN-sensitive determining region (ISDR) 718 IgM See Immunoglobulin M (IgM) IGV1 See Isolated gastric varices type 1 (IGV1) IHA See Indirect hemagglutination (IHA) IL-6 See Interleukin-6 (IL-6) Iliac vein conduit 1515 Illicit drug paraphernalia 825 Iloprost 522 Imaging noninvasive 127 role of 95 Imaging modalities, performance characteristics of 94–95 Imatinib mesylate 980 Immune competence 377 Immune dysregulation 926

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Immune response, overview of 1468–1470 Immune theory 1071 Immunodeficiency 1381 Immunogenic protein complexes, production of 701 Immunogens 893 Immunoglobulin (Ig) 20 54 serum, elevation of 54 Immunoglobulin A (IgA) 889 abnormal sinusoidal deposition of 1129 Immunoglobulin M (IgM) 668 712 729 740 1332 Immunohistochemical staining 758 for insulin receptors 1124 Immunomodulation nonspecific 784 specific hepatitis b virus 784 Immunomodulatory therapy 784 Immunopathology 251–253 Immunoprecipitation 36 Immunostain 251 1255 for hepatitis B antigens 253 with Mallory bodies 252 with monoclonal antibodies 251 with polyclonal antibodies 252 Immunosuppressant therapy 377 Immunosuppression 1418 1450 1467–1477 1481 1482 1545 1546 complications of 1450 general features of 1468–1470 goals of 1467 1477 induction, OKT3 1477 pharmacologic side effects 602 primary goal of 1482 side effects of 1481 1483 steroid 1450 steroid-free, in hepatitis C virus 1450 therapeutic 1482 Immunosuppressive agents 1296 1467 1477 in liver transplantation 1477 overview of 1470–1471 and target pathways 1470 1471 types of 1470 Immunosuppressive drugs 626 967–971 use of 1351 Immunosuppressive medications 1494 Immunosuppressive therapy 760 Immunosuppressive treatment 619 Index bleeding episode 446 Indian childhood cirrhosis (ICC) 281 1320

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Indicator dilution technique 439 Indinavir 231 951 1412 Indirect hemagglutination (IHA) 1353 Indocyanine green (ICG) 20 27–28 1268 clearance test 1268 role of 19 structural formula for 27 Indomethacin 503 518 542 1442 Inducible nitric oxide synthase (iNOS) 514 Infantile hemangioendothelioma 1219 diagnosis of 1219 treatment of 1219 Infarction, hepatic 149 Infarcts of Zahn 205 Infectious granulomas, cause of 284–287 Infectious mononucleosis 724 Inferior right hepatic vein (IRHV) 133 catheterization of 133 Inferior vena cava (IVC) 132 139 1539 obstruction 426 posttransplant, balloon dilatation and stenting of 139 stricture 140 thrombosis 1172 Inflammation 408 874 hepatic 374 403 severity of 404 Inflammatory bowel disease (IBD) 7 665 688 1490 1498 treatment for 671 Inflammatory cell infiltration 758 Inflammatory disease, chronic 408 Inflammatory lesions, space-occupying 282–288 Inflammatory markers, production of 366 Inflammatory pseudotumor 282 284 1221 1392 hepatic, prognosis of 1221 Inflammatory signaling 403 Infliximab 981 clinical trials of 900 Influenza 1493 Infrared spectrometry, nondispersive 33 Ingestion 373 INH See Isotonicotonic acid hydrazide (INH) Inhibitors of apoptosis (IAP) 318 Injury morphologic patterns of 308 vascular patterns of 295 Innate cellular response 817 Innate immune response 1012

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Innate immune system 1012 iNOS See Inducible nitric oxide synthase (iNOS) INR See International normalized ratio (INR) Insufficiency, hepatic 569 Insulin 207 Insulin resistance (IR) 320 330 370 1125 1135–1136 1412 1141 expected manifestations of 1135 improvement in 1147 metabolic effect of 331 peripheral 365 Integrins 397 398 Intensive care unit (ICU) 1481 Intercellular adhesion molecule-1 (ICAM-1) 684 Interface hepatitis 264 268 Interferon α (IFN-α) 1325 Interferon α-2a 1219 Interferon (IFN) 771 980 1053 1407 1438 pegylated 838 resistance 811 Interferon monotherapy 73 1407 Interferon-α 408 788 dose regimen 773 hepatitis B e antigen–negative patients 773 hepatitis B e antigen–positive patients 773 interferon-β/γ, combination therapy 774 and lamivudine, standard/pegylated 782–783 nonresponders 783 pegylated 773–774 980 dose regimen 774 efficacy of 773–774 HBeAg-negative chronic hepatitis 774 HBeAg-positive chronic hepatitis 773 pegIFN-α2a 774 standard, response to 774 prednisone priming, role of 772 standard 771–773 efficacy of 771–772 therapy with adverse effects of 774 hepatitis B e antigen (HBeAg)–negative patients 773 hepatitis B e antigen (HBeAg)–positive patients 772 myelosuppressive effects 774 outcome of, long-term 772–773 treatment of, nonresponders to 772 Interferon-β/γ 774 Interferon-γ (IFN-γ) 609 716 Interleukin-2 (IL-12) 609 1477

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Interleukin-6 (IL-6) 1136 Internal ribosomal entry site (IRES) 711 809 International Association for the Study of the Liver (IASL) 268 International normalized ratio (INR) 51 354 1188 1547 Intestinal failure 380 P.I-27 Intestinal flora 588 Intestinal hypomotility 647 Intestinal transit, role of 645 Intestinal transplantation 380 Intra-abdominal infections 46 Intracardiac shunting 516 Intracellular binding 220–221 Intracellular cell adhesion molecule (ICAM) 1472 Intracellular signaling 409 Intracranial hypertension 572 Intracranial pressure (ICP) 578 613 Intrahepatic biliary epithelium 42 Intrahepatic cholangiocarcinoma 1221 Intrahepatic cholestasis 20 Intrahepatic cholestasis of pregnancy (ICP) 1281 1283 1285–1287 clinical and biochemical findings 1285–1286 complication of, prematurity 1286 diagnosis of 1285 estrogen, role of 1286 management of, medical and obstetric 1286–1287 maternal and fetal outcome of 1286 pathogenesis of, ABCB4 gene, role of 1286 pathology of 1285 pathophysiology of 1286 progesterone metabolism 1286 treatment of 1287 Intrahepatic circulation, pharmacologic manipulation of 448–451 Intrahepatic cysts 1244 Intrahepatic ductal anatomy 160 Intrahepatic ducts 194–195 paucity of 278 Intrahepatic hematoma 64 Intrahepatic narrowing, multifocal 165 Intrahepatic shunting 556 formation of 210 Intrahepatic vasculature 1190 Intraluminal thrombi 1209 Intramural glands 195 Intramuscular immunoglobulin 828 Intramyelenic edema 1484 Intraperitoneal hemorrhage 64

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Intratracheal aerosol 1078 Intravariceal pressure 432 Intravenous drug 7 users of 7 Intravenous drug use 825–826 Intravenous fentanyl 62 Intravenous ganciclovir 1483 Intravenous hematin 1085 Intravenous injection 371 Ionizing radiation, effective doses of 91 Iproniazid 974 IR See Ischemia-reperfusion (IR) Irbesartan 952 IRES See Internal ribosomal entry site (IRES) IRHV See Inferior right hepatic vein (IRHV) Iron 248–251 accumulation of, prevention of 1042 basolateral transfer of 1046 dietary, increased absorption of 1054 homeostasis 1043 induced toxicity, to minimize 1054 ionic, absorption of 1046 overload 1043 diagnosis of 1042 quantification of 98 Iron absorption, duodenal determinants of 1046–1048 Iron depletion 1053 Iron overload 1563–1564 African 1055 hepatocellular carcinoma 1055 diagnosis of 1564 neonatal 1055 non–HFE-related 1055 parenchymal, degree of 1055 parenteral 1043 1054–1055 secondary 1043 1054–1055 Iron overload syndromes, classification of 1043 1043 Iron staining, evaluation of 1051 Iron storage disorders 1041–1055 Iron therapy 1106 Iron-free foci 294 Iron-responsive elements (IREs) 1044 Iron-sensing pathway 1041 Ischemia 183 1185 hepatic 703 Ischemia-reperfusion (IR) 318 injury 321

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Ischemic cholangiopathy 1185 1186 1191 Ischemic hepatic injury 329 Ischemic hepatitis 1185–1189 1194 clinical features of 1187–1189 causes of 1187 histologic features of 1187 histology of 1188 outcome of 1187–1189 pathophysiology of 1187 serum alanine aminotransferase (ALT), pattern of 1188 treatment of 1189 Ischemic injury 1138 1185 1187 1191 aminotransferase levels 701 ISDN See Isosorbide dinitrate (ISDN) ISDR See IFN-sensitive determining region (ISDR) Ishak score 269 405 Islet cell tumors 143 Isocarboxazid 974 Isocitrate dehydrogenase (ICDH) 41 measurement of 41 Isoechoic lesion 109–111 Isoenzyme cytosolic 36 mitochondrial 36 Isoflurane 701 958 Isolated gastric varices type 1 (IGV1) 447 436 Isolated pancreatic tuberculosis 1382 Isoleucine 382 574 Isoniazid (INH) 603 877 1383 1440 Isoproterenol 428 Isosorbide dinitrate (ISDN) 449 453 Isosorbide-5-mononitrate (IMN) 453 Isotonicotonic acid hydrazide (INH) 1412 Itching 237 Ito cells 291 Itraconazole 948 IVC See Inferior vena cava (IVC) Ivemark's syndrome 1310

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Copyright ©2007 Lippincott Williams & Wilkins > Back of Book > Index > J

J Jamaican morning sickness 941 Jamaican vomiting sickness 1291 Janus kinase (JNK) inhibitors, use of 321 Janus kinase 2 (JAK2) 353 mutation 422 54 descriptions of 807 differential diagnosis of 6 evaluation of 158 obstructive 36 158 1064 patient with history taking for 5–7 physical examination of 6 8–19 postoperative 697–705 942–943 due to biliary obstruction 698–700 due to bilirubin load 703–704 causes of 698 699 endoscopic retrograde cholangiopancreatography (ERCP) 699 evaluation of 698 hepatic resections 700 following liver transplantation 705 liver blood test abnormalities 699 management of 702 parenteral nutrition, associated with 704–705 pathogenesis of 700 portal vein embolization 700 presence of 332 risk factors of preoperative, evaluation of 698 of sepsis 1380 Jejunoileal bypass 1140 Jejunoileal bypass surgery 282 Jejunoileal bypass–granulomas 1441 Jejunostomy tubes 384 Jin Bu Huan 984 Joubert's syndrome 1241 Jugular venous distension 1193 Juvenile hemochromatosis 1043 1048

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Editors: Schiff, Eugene R.; Sorrell, Michael F.; Maddrey, Willis C. Title: Schiff's Diseases of the Liver, 10th Edition Copyright ©2007 Lippincott Williams & Wilkins > Back of Book > Index > K

K K-F rings See Kayser-Fleischer (K-F) rings Kaposi sarcoma (KS) 1417 incidence of 1417 Kasabach-Merritt syndrome 1210 1219 1335 Kasai operation 174 Katayama fever 1365 Kava 984 Kava pyrones 984 Kayser-Fleischer (K-F) rings 18 607 1023 1024 1031 slit-lamp detection of 1032 Keratinocyte growth factor 401 Kernicterus 217 risks of 219 Ketoconazole 948 1361 Kifunensine (KIF) 1078 Kikuchi lymphadenitis 1441 King's College criteria 615–618 prognostic 617 Pittsburgh analysis 616 validation of 616 Knodell histology activity index 269 Knodell score 269 1407 KS See Kaposi sarcoma (KS) P.I-28 Kupffer cells 92 110 111 198 200 207 246 254 293 320 399 400 408 890 894 901 1204 1206 1217 135 –1389 activation 343 absence of 1215 activated 926 cell debris in 247 depletion of 321 hyperplasia 333 335 352 378 1433 infiltration of 400 influx of 401 protoporphyrin accumulation in 253

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Copyright ©2007 Lippincott Williams & Wilkins > Back of Book > Index > L

L Labetalol 952 Laboratory tests 19–56 capacity liver 20–35 Lactate, accumulation of 611 Lactate dehydrogenase (LDH) 41 333 352 701 1187 1381 isoenzyme of 41 Lactobacillus bifidus 586 Lactulose 382 586 587 592 Lafora's disease 247 290 Laminin 200 398 Lamivudine 605 716 721 760 770 775–778 784 789 1295 1403 1405 1534 1536 1563 and adefovir, combination of 783 adverse events of 777 benefit of 1534 disadvantage of 1534 dose regimen 777–778 hepatitis B e antigen–negative patients 778 hepatitis B e antigen–positive patients 777–778 monotherapy 775 efficacy 775–776 HBeAg positive chronic hepatitis B 775 HBeAg-negative chronic hepatitis B 775 interferon α treatment, nonresponders to 775 liver disease, advanced 775 resistance 776–777 HBeAg-negative chronic hepatitis B 777 response durability of 776 predictors of 776 and telbivudine, combination of 783 treated patients, outcome of, long-term 777 Lamivudine monotherapy 774 Lamotrigine 231 972 Langerhans' cell histiocytosis 278 Lanreotide 453 Laparoscopic cholecystectomy 165 167 639 Laparoscopic ultrasonography 70 Laparoscopy 66–70 1214 complications of 70–71 diagnostic 69 indications for 69–70 69 staging 70 techniques of 67–69 use of 66 Large animal steatosis 1134–1135 Large ducts 193–194 Large-volume paracentesis 548 Laryngotracheobronchial cartilage 335

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Latent tuberculosis infection (LTBI) 948 Lazaroids 1147 LCHAD See Long-chain 3-hydroxyacyl coenzyme A dehydrogenase (LCHAD) LCTs See Long-chain triglycerides (LCTs) L-deoxythymidine (LdT) 782 and lamivudine 782 LDH See Lactate dehydrogenase (LDH) LDL See Low-density lipoprotein (LDL) LDLR See Low-density lipoprotein receptor (LDLR) LDLT See Living donor liver transplantation (LDLT) LdT See L-deoxythymidine (LdT) Lead poisoning 1108 protoporphyrin, zinc, elevated levels of 1108 LEC See Long-Evans Cinnamon (LEC) Lectin-stimulated cells 1352 LEE See Liver enzyme elevation (LEE) Leflunomide 967 Left hepatic vein (LHV) 132 Left ventricular dysfunction 520 Legionella pneumophila 1383 Legionnaires disease 1383 Leiomyomas 1172 Leishmania 249 1360 1436 Leishmania donovani 1360 1416 Leishmania infection 1359 1360 Leishmaniasis 1359–1362 Lennox-Gastaut syndrome 973 Lenticular degeneration 1024 Lepra bacilli 284 Leprosy 1436 Leptin 403 409 1136 deficiency 1129 Leptospira canicola 1385 Leptospirosis 1385–1386 Lesions 300–301 characteristic of 669 Leucine 382 574 Leucine aminopeptidase 47–49 elevation in 48 measurement of 49 serum 49 electrophoresis of 48 method for 48 Leukemia 198 409 424 1567 Leukocytapheresis 901 Leukocyte function-associated antigen (LFA-1) 668 Leukocytes 196 370 1472 polymorphonuclear 403 Leukocyte zinc concentration, measurement of 373 Leukocytosis 352 558 650 1190 1240 1353 1355 Leukopenia 757 1232 Leukotriene antagonists (LTA) 980–981 Leukotriene synthesis 370 LeVeen shunt, insertion of 552 Levodopa 589 Levofloxacin 944

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LFA-1 See Leukocyte function-associated antigen (LFA-1) LFT See Liver function test (LFT) LHV See Left hepatic vein (LHV) Lidocaine 34 62 metabolite formation of 34–35 Lidofenin, Tc 99m 232 Liebermann-Burchard reaction 250 Ligandins 20 Light microscopy 1029 Light palpation 10 Light-chain amyloidosis (AL) 339 LINEs See Long interspersed repetitive elements (LINEs) Linton-Nachlas tube 454 474 Lipid metabolism 370 disorders of 1314–1315 Lipid peroxidation 402 953 1136 Lipid-lowering drugs 954 hydroxymethylglutaryl-coenzyme A reductase inhibitors 954 nicotinic acid (niacin) 954 Lipids 290 370 Lipoapoptosis 320 Lipocyte 398 Lipodystrophy 1129 1141 1413 findings of 1129 Lipofuscin 205 229 250 270 pigment 288 stains 288 Lipogenesis 203 Lipogranulomas 288 288 1425 1426 1426 LipoKinetix 985 Lipolysis 1147 1413 Lipopolysaccharide (LPS) 1380 Lipoprotein, production of 366 Lipoprotein metabolism 1127 abnormal 1139–1140 Lipoprotein receptor–related protein (LRP) 1071 Lipoxygenase 505 Lisinopril 1497 Listeria monocytogenes 1381 Listeriosis 259 282 1384–1385 Lith genes 645 Lithotripsy 160 Liver 20 366 368 1070 1185 1186 1186 1255 adenomatosis of 1235 benign solid lesions of 1201 benign tumors of 1201 1202 cavernous hemangioma of 129 129 concentration of copper in 1032–1033 contour of 87 cystic diseases of 1236–1246 division of 185 embryology of 187–189 enlargement of 10 Entamoeba histolytica, invasive process of 1351 extracellular matrix (ECM) biologic activity of 397–398

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composition of 396–397 fat content of, chemical shift imaging 94 disposition of fatty acid 1135 fatty infiltration of 330 1100 function tests 369 use of 54–56 functional unit of 1186 granulomas of 1425–1443 histologic appearance of 209 histologic examination of 1383 ischemia 138 Kupffer cells of 215 large vessels of 189–193 lymphomatous infiltration of 343 607 malignant tumors of 139 P.I-29 transarterial chemoembolization of 143–147 transarterial radioembolization of 147–148 metastasis to, in pregnancy 1293 metastatic lesions, ultrasonography 85 microanatomy of 195–205 microscopic appearance of 1192 microvasculature of 183 necrosis 138 nodular diseases of 1229–1236 1232 diagnostic approach to 1236 nodular hyperplasia of 190 nodular regenerative hyperplasia of 336 nomenclature for resections of 186 noncirrhotic 289 noninvasive imaging of 83 93 computed tomography (CT) 86–88 embolotherapy of 143 ultrasound 83–86 nonparenchymal cells of 193 as normal fat-storing organ 1134–1135 palpation of 11 12 partial nodular transformation of 424 perfused, histologic examination of 1105 physioanatomic considerations of 183–210 planes of division in 186 portal tract from 196 positron emission tomography (PET) scan 89 posterior view of 184 in pregnancy, normal 1282–1283 hemodynamics 1282 liver tests 1282–1283 pathology of 1282 physical examination of 1282 serum protein and lipids 1282 ultrasonographic examination of 1282 protoporphyrin accumulation in 1105 with Riedel's lobe 10 185 segmental anatomy of 185–187 487 signal intensity of, comparison to spleen 97 splanchnic blood flow 183

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surface anatomy of 184–185 surface, direct visualization of 61 in systemic disease 329–344 tests of biosynthetic capacity of 49–53 tests used to detect fibrosis in 53 three-dimensional organization of 200–203 vascular diseases of 1171–1181 venous anatomy of 132 Liver abscesses 1214 1351–1356 amebic 1351–1353 mixed 1351 percutaneous drainage of 150 pyogenic 151 1351 1353–1356 percutaneous treatment of 150 Liver acinus blood supply of 204 in human 201 Liver adenomatosis 1214 Liver allografts, split 1514 Liver allograft rejection, acute 1484 Liver and spleen, location of 10 75 blind 107 coagulopathy management in 358 British society of gastroenterology guidelines on 359 complications of 65 diagnostic laparoscopy with 61 in Dubin-Johnson syndrome 233 electron micrographs of 1030 “gold standard” 94 guided 107 hematoxylin–eosin stain (×100) of 741 hemorrhage after 64 risk factors for 64 histologic appearance of 1077 indications for 72–75 inflammation in 31 laparoscopic 61 outpatient, criteria for 62 percutaneous 61–65 340 1208 1219 complications associated with 105 role of 61 in special patient populations 66 specimens 267 systematic approach to 246–253 transabdominal 137 transcutaneous puncture for 184 transjugular 61 65–66 137–138 1033 transvenous 137 ultrasound 106 guidance for 105–107 Liver biopsy specimens with α 1 -antitrypsin (α 1 -AT) deficiency 290 Liver cell adenoma 1214 coagulative degeneration 295 death of 608 endoplasmic reticulum (ER) of 1063

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injury 1076 necrosis 9 plasma membranes 718 Liver cirrhosis 867 1254 Liver cysts 101 102 1240 multiple 101 ultrasound image 101 Liver damage 1071 1076 alcohol-induced 882 alcohol-mediated 891 cholestyramine, administration of 1106 instances of 607 in porphyria cutanea tarda (PCT) 1085 1099–1102 in protoporphyria 1085 severity of 604 spectrum of 607–609 607 Liver decompensation 1409 1124 alcoholic 37 403 832 associated with particular classes of drugs 943–986 coagulation assay characteristics of coagulopathies associated with caused by red blood cell abnormalities 351–352 cholestatic 317 350 372 681 chronic 61 64 72 333 353 357 365 372 395 396 399 501 513 519 698 712 739 808 825 938 942 1034 etiology of 825 pulmonary complications of 493 child-pugh grading of 487 chronic alcoholic 36 clinical manifestations of 1064–1065 coagulopathy of 350 cystic 1359 decompensated 442 signs and symptoms of 15 diagnosis in pregnancy 1283 1284 drug-induced 266 281 923–986 causes of 931 effect on energy requirements 367 end-stage 369 486 493 871 1035 fatty 843–844 fibrotic 409 flucloxacillin 943–944 genetic/metabolic 1310–1323 idiosyncratic drug-induced, types of 923 HCV-induced 1405 helminthic 1362–1373 diagnosis of 1363 imaging methods 1362 1363 HFE mutations in, analysis of 1053 1054 high-fat diet, effect of 885 host responses of 813–819 human, physioanatomic aspects of 206–210 hyperbilirubinemia in 25 impact of 329 in infancy and childhood 1305–1343 infiltrative 56 inflammatory 408

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malnutrition in patients with 377 medication-induced 7 metabolic 1459–1460 nonalcoholic 74–75 378 noncirrhotic chronic 882 nonfibrotic 1365 nutritional management of patients with 380–384 parenchymal 9 24 parenteral nutrition, associated with 1327–1328 pathogenesis of 813–819 patient with history taking of 5–19 physical examination of 5–19 pediatric patients with 1453 polycystic 195 preexisting 930 in pregnancy, intercurrent 1283 1292–1297 pretransplantation 171 progressive 336 365 risk factors for 74 in protoporphyria 1105 pulmonary manifestations of 513–523 P.I-30 red blood cell abnormalities caused by 350–351 tacrine-induced 1015 therapeutic implications 323–324 therapeutic targets in 323 Liver disorders 45 in pregnancy, division of 1281 tests, classification of 20 Liver donation/resection, donor complications after 1521 Liver dysfunction 20 26 44 329 354 1064 1185 causes of 54 chronic 593 hyperemesis, associated with 1281 idiosyncratic forms of 699 indicators of 30 presence of 19 Liver enzyme elevation (LEE) 1412 Liver enzymes 1409 abnormalities 1052 elevated 1051 1288–1289 Liver failure 378 574 580 825 928 957 959 1135 1190 1403 1411 1414 1417 acetaminophen-induced 1461 acute 931 937 1024 1412 drugs associated with 935 chronic 865 fatal fulminant 974 fulminant 712 1033 1037 hyperacute 343 prothrombin time 618 Liver fibrosis 20 53 398 402 689 degree of 33 intralobular 1361 Liver flukes 174 Liver function, causes of 1558

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Liver function test (LFT) 19 931 Liver graft, split, proposed method for division of 1522 Liver imaging 1130 1386 Liver in pregnancy 1281–1297 Liver injury 63 368 397 408 719 723 873 880 932 935 937 947 954 962 965 966 977 978 981 982 1012 106 advanced 886 alcohol-induced 873 892 management of 875 alcohol-related 901 alcoholic 279 in α 1 -antitrypsin (α 1 -AT) 1073 associated with antithyroid therapy 333 chronic 405 719 disease mechanisms 319–323 dose-dependent 925 drug-induced 961 histologic patterns of 700 mechanisms of 1005–1017 susceptibility, variation in 1013–1014 fatal 963 flucloxacillin-induced 943 halothane-induced 942 957 in HIV-infected patients, causes of 1402 ketoconazole-induced 949 mechanism of 313–324 962 973 1075–1077 basic 313–318 methyldopa-induced 951 1015 pathogenesis of 952 noninvasive markers of 71 in PIZZ individuals, pathogenesis of 1071 patterns of 933 progression vs. recovery 1012–1013 sulfonamide-induced 945 terbinafine-associated 949 toxic 403 Liver–kidney microsomal (LKM-1) 866 Liver lymph 536 Liver parasites 1359 Liver parenchyma 70 103 343 625 890 1191 1193 1204 1206 1209 1217 computed tomography 97 contrast-enhanced computed tomographic scan 100 replaced with cysts 108 Liver pathology 986 Liver regeneration, initiators of 609 Liver resection intrahepatic recurrence, risk factors for 1267 preoperative evaluation 1268 Liver retransplantation 1545 Liver rot 1368 Liver size 9 percussion 9 Liver support artificial 620–623 bioartificial 622 623–625 HepatAssist 623

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consideration in 622 extracorporeal 620–625 HepatAssist, schematic representation of 624 Liver synthetic dysfunction 1064 Liver tests, in normal pregnancy 1283 Liver tissue enzyme values in 49 structural integrity of 245 Liver toxicity 1412 Liver transplant 29 recipients 769–770 359 benefit 1455–1456 candidates for, selection of 1454–1461 in children 1342–1343 1460 disease progression 1456 donor morbidity 1451 donor safety 1518 donor selection 1517–1518 dysfunction in 1483 early clinic visits 1485–1486 efficacy of 522 in erythropoietic protoporphyria (EPP) 1106 ferrochelatase defect 1106 first 6 months after 1481–1487 floor care 1482–1485 goal of 1490 graft function in 1483 indications for 421 491 1342 1452 intensive care unit, management of 1481–1482 Karnofsky performance scores 1455 King's college and clichy criteria for 1460 late clinic visits 1486–1487 living donor 1451 1453 1454 1461–1462 indication for 1274 patients selected for 1461 use of 602 long-term management of 1450–1451 mortality risk 1454 ongoing controversies 1519 orthotopic 350 1070 1077 outcome of 492 overview of 1521 pediatric considerations 1460 posttransplantation, survival results 1456 preanhepatic stage of 358 during pregnancy 1297 prevention of hepatitis B after 1494 psychological improvement after 1490 recipient procedure 1512–1513 recipient results of 1519–1521 recurrent disease 1451–1452 reduced-size 1513 retransplantation 1451–1452 right lobe 1520 risk factors 492 selection and timing of 1449 1453–1462

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selection criteria for 615–619 split 1511 1513–1516 ex vivo techniques for 1514–1515 in situ techniques for 1515 results of 1515 steroids 1471 surgical options 1451 surgical options of 1511–1521 thrombosis rates in randomized trials using antifibrinolytic agents in 359 timing of 1461–1462 treatment of osteoporosis after 1495 waiting list, probability of removal from 1458 Liver transplantation surgery, hemodynamic changes 321 Liver transplantation therapy, application of 1454 Liver tuberculosis 1414 Liver tumors 928 benign 1296 Liver X receptor (LXR), major ligands of 643 Liver–kidney microsomal-1 (anti-LKM-1) antibody 1328 Living donor liver transplantation (LDLT) 1462 1511 1516 1529 Living donor right lobe graft, technique for procurement of 1518–1519 Living donor right lobe transplantation, morbidity after 1521 Living donor transplantation 1037 in adult recipients 1516–1517 P.I-31 LKM See Anti–liver/kidney microsomal (LKM) LKM-1 See Liver–kidney microsomal (LKM-1) Lobe graft, implantation of 1525 Lobe hypertrophy 99 Lobular necrosis 1029 Lobules 183 Local therapy 69 Long interspersed repetitive elements (LINEs) 1352 long-chain 3-hydroxyacyl coenzyme A dehydrogenase (LCHAD) 1281 1291 Long-chain triglycerides (LCTs) 370 Long-Evans Cinnamon (LEC) 322 Long-term survivors, causes of death in 1490–1493 Loop-sheet insertion mechanism 1072 Lovastatin 610 Low platelets syndrome 1288–1289 Low-density lipoprotein (LDL) 370 642 682 1473 1495 Low-density lipoprotein receptor (LDLR) 718 Losartan 952 Lovastatin 954 LPS See Lipopolysaccharide (LPS) LRP See Lipoprotein receptor–related protein (LRP) Lsiria sinclaivii 1477 LT See Liver transplantation (LT) LTBI See Latent tuberculosis infection (LTBI) Ludwig system, portal stage in 683 Lumican 396 Luminal polypeptide 1074 Luminexx stent 138 Lung cancer 1504 Lung disease clinical manifestations of 1065

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destructive 1065 Lung microvasculature 517 Lung perfusion scanning 515 Lung transplantation 1063 Lupoid hepatitis 334 865 Lupus erythematosus 680 LXR See Liver X receptor (LXR) Lyme disease 1387 Lymph, formation of 198–199 Lymph flow 442 Lymph node biopsies 1432 Lymph nodes 442 enlarged 683 peripheral 343 Lymphadenopathy 9 337 756 937 1208 1415 hilar 341 palpable 343 supraclavicular 9 Lymphatics 193 198 superficial 193 Lymphocytes 257 723 818 901 1070 1071 1429 1433 1434 cytotoxic CD8+ 1402 liver-associated 200 sinusoidal 200 Lymphocytic choriomeningitis virus (LCV) 818 Lymphocytic sialadenitis 336 Lymphoid follicles 263 273 Lymphoid hyperplasia 1437 Lymphoma 137 165 342–343 424 1486 1502 1504 1567 acute liver failure secondary to 343 Lymphopenia 1476 Lysomotropic agents 316 Lysosomal permeabilization 316 320 Lysosomal phospholipidosis 252 Lysosomes 316 1306 intraorganelle pH of 316 phospholipids, accumulation of 316

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Copyright ©2007 Lippincott Williams & Wilkins > Back of Book > Index > M

M MAC See Mycobacterium avium complex (MAC) Macaque monkeys 371 Macroaggregated albumin 516 518 519 Macrocytosis 373 887 Macronodular 1230 Macrophages 1433 Macroregenerative nodule (MRN) 1218 1229 1230 imaging studies 1218 Macrovesicular steatosis 1141 Maddrey discriminant function (DF) 894 Maddrey's score 320 Madelung's disease 1129 Magnetic resonance angiography (MRA) 128 Magnetic resonance cholangiopancreatography (MRCP) 104 133 157 652 1416 1485 1517 Magnetic resonance imaging (MRI) 74 91– 92 127 352 584 652 1130 1205 1230 1256 advantages of 91 98 contrast agents 92 modification of 99 screening test 98 Magnetic resonance spectroscopy (MRS) 94 501 577 578 1127 proton 584 584 Magnetic susceptibility 99 measurement 98–99 Magnetization transfer ratio (MTR) 578 Maintenance therapy with peginterferon 1410 Major histocompatibility complex (MHC) 680 1071 1407 Major papilla 194 Malabsorption 365 366 372 Malaria 1359–1360 falciparum 1360 Malignant disease 1384 Malignant hepatocytes 1255 Malignant hypervascular tumors 1205 Malignant stricture dilatation 141–143 Malignant tumors, surgical options 1265–1275 Mallory bodies 251 275 294 889 1130 1139 1255 in alcoholic hepatitis 281 282 in ballooned hepatocyte 281 formation 281 localization of 1138 in nonalcoholic steatohepatitis 282

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presence of 280 ultrastructural appearance of a 280 Mallory's hyaline 330 Mallory-Weiss syndrome 1290 Mallory-Weiss tear 891 Malnutrition 365 373–377 1141 1381 Malondialdehyde (MDA) 893 1136 Maltese, red birefringent 253 Mammalian target of rapamycin (mTOR) 1470 Mangafodipir trisodium 92 Manganese 573 Mannitol 613 Manometry 135 MAP See Mean arterial pressure (MAP) MAPK See Mitogen-activated protein kinase (MAPK) MARS See Molecular adsorbent recirculating system (MARS) Masculine obesity 378 Masson trichrome 246 Masson trichrome stain 246 269 MAST (Michigan Alcoholism Screening Test) 887 Mast cells 1105 Mastocytosis 198 MAT See Methionine adenosyl transferase (MAT) Matrix degradation 402 Matrix metalloproteinase (MMP) 398 Matrixins 399 MCD See Methionine–choline–deficient (MCD) MCTs See Medium-chain triglycerides (MCTs) MDA See Malondialdehyde (MDA) MDCT See Multidetector row computed tomography (MDCT) MDMA See 3,4-methylenedioxymethamphetamine (MDMA) Mean arterial pressure (MAP) 613 Mean corpuscular volume (MCV) 887 Mebendazole 1372 Meckel's syndrome 1241 Medical care 1493–1498 Medium-chain triglycerides (MCTs) 370 use of 370 Megamitochondria 252 320 MEGX See Monoethylglycinexylidide (MEGX) Melanin 233 MELD See Model for End-Stage Liver Disease (MELD) MELD score See Model for End-Stage Liver Disease (MELD) score Melioidosis 1385 Melphalan 340 Membrane attack complex inhibitory factor 353 Membrane lipid peroxidation 884 Membrane-type 1 matrix metalloproteinase (MT1-MMP) 399 Meningitis 1415 Menkes disease 1025 1032

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Menthol 231 6-Mercaptopurine 871 970 Mesenchymal cell tumors 409 Mesenchymal hamartoma 1220 1336 Mesenchymal stroma 306 1220 1245 Mesenteric artery catheterization of 129 superior 192 Mesenteric veins, superior 189 Mesocaval shunt 489 Messenger ribonucleic acid (mRNA) 50 399 713 818 1016 1065 Metabolic bone disease 671–672 690 Metabolic diseases 266 288–295 inherited 1141 P.I-32 Metabolic encephalopathy 577 583 588 Metabolic idiosyncrasy 947 Metabolic liver disease 1311 Metabolic syndrome 365 378 938 942 1118 1126 1126 1131 1135 1139 Metabolic zonation 203 204 control of 203 Metabolome 1016 Metachromatic leukodystrophy 250 Metalloproteinases 399 direct expression of 410 Metastases 308 Metastatic adenocarcinoma 142 Metastatic carcinoma 46 Metastatic colorectal carcinoma, TACE, use of 147 Metastatic disease, hepatic arteriogram of 130 Metavir 823 842 Metavir score 405 Metformin 330 960 1149–1150 1485 Methacetin 33 Methimazole 956 Methionine adenosyl transferase (MAT) 893 Methionine metabolism 371 abnormal 893 Methionine plasma clearance 371 Methionine–choline–deficient (MCD) 1134 Methotrexate 75 337 689 690 871 967–970 1140 1442 clinical features of 969 hepatotoxicity 970 histology of 969 laboratory data for 969 therapy 930 Methotrexate liver toxicity, risk factors for 969 Methotrexate fibrosis, prevention of 969–970 Methotrexate-induced hepatotoxicity 75 Methoxyflurane 701

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3,4-Methylenedioxymethamphetamine (MDMA) 977 Methyl-t-butyl ether (MTBE) 655 Methyldopa 940 1440 Methylene dianiline (MDA) 977 Methylphenidate 975 Metronidazole 588 1353 MHC See Major histocompatibility complex (MHC) MHVs See Middle hepatic veins (MHVs) Microabscess 282 Microcatheters 128 Microcirculation, hepatic 205 Microcirculatory plugging 610 Microfilaments 874 Microhamartomas, biliary 300 Microlithiasis 649 treatment of 656 Micronodular 1230 Micronodular cirrhosis 953 Micronutrient abnormalities 884 Micronutrient deficiency 1140 Micronutrients 371 deficiency of 374 Microsomal cytochrome P-450 505 Microsomal enzyme induction 936 Microsomal inducer 30 Microsporidia 174 Microsporidial infection 1416 Microvascular subunits, hepatic 202 Microvesicular steatosis 607 938 984 986 1141 1291 1320 drugs associated with 936 Microwires 128 Midazolam 62 159 Middle hepatic veins (MHVs) 131 1514 Middleton method 10 Midodrine 508 administration of 507 Milan criteria 1457 for liver transplantation 1274 Milia 1099 Miliary tuberculosis with necrosis 286 Milk thistle 846 Mimic neoplasia 1389 Mineralocorticoids 498 Mineral deficiency, assessment of 374 Minerals major 370 trace 370 deficiency of, assessment of 375 Miniepidemics 927 Minilaparotomy 654

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Minimal immunosuppression 1401 Minnesota tube 454 Minocycline 940 Mirizzi's syndrome 651 Misoprostol 906 oral administration of 507 Mitochondria 36 317 330 1011 abnormalities 317 astrocytic 573 rupture 1011 swelling 318 Mitochondrial damage 1076 Mitochondrial disease 1139 findings suggestive of 1129 Mitochondrial dysfunction 318 323 885 893 1011 activation 320 Mitochondrial hepatopathies, primary 1319–1321 Mitochondrial hepatotoxicity, hallmarks of 950 Mitochondrial heteroplasmy 1129 Mitochondrial injury 938 copper overload 1320–1321 Reye's syndrome 1319–1320 Mitochondrial isoenzyme 36 Mitochondrial permeability transition (MPT) 317 319 1011 Mitochondrial permeabilization 317 Mitochondrial toxicity 950 Mitogen-activated protein kinase (MAPK) 320 401 1139 1352 Mitomycin-C 143 146 MMF 1471 See Mycophenolate mofetil (MMF) MMP See Matrix metalloproteinase (MMP) MMTV See Murine mammary tumor virus (MMTV) Mnemonic FARE 7 Model for End-Stage Liver Disease (MELD) 354 406 488 497 500 670 691 698 879 895 1257 1454 1511 1530 1545 1547 for liver allocation 1274 mortality risk, comparison of 1456 plot of 1454 Model for End-Stage Liver Disease (MELD) score 488 1449 1455 hazard ratio 1456 Molecular adsorbent recirculating system (MARS) 509 620 schematic diagram of 621 albumin-bound toxins 621 Molecular chaperones 1073 Molecular technology application of 214 Monensin 1089 Monoclonal antibodies 1476–1477 OKT3 1476 pyruvate dehydrogenase complex-E2 (PDC-E2) 1560 Monoethylglycinexylidide (MEGX) 34 1268

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Monoglucuronide 26 Monohydroxy lithocholates 642 Mononucleosis hepatitis 257 Montelukast 981 Mortality 446 bleeding-related 447 Movat pentachrome stain 247 Moxifloxacin 944 MPD See Myeloproliferative disorder (MPD) MPT See Mitochondrial permeability transition (MPT) MRA See Magnetic resonance angiography (MRA) MRCP See Magnetic resonance cholangiopancreatography (MRCP) MRI See Magnetic resonance imaging (MRI) MRN See Macroregenerative nodule (MRN) mRNA See Messenger ribonucleic acid (mRNA) MRP2 See Multidrug resistance–associated protein 2 (MRP2) MRS See Magnetic resonance spectroscopy (MRS) MT1-MMP See Membrane-type 1 matrix metalloproteinase (MT1-MMP) MTB See Mycobacterium tuberculosis (MTB) MTBE See Methyl-t-butyl ether (MTBE) mTOR See Mammalian target of rapamycin (mTOR) MTR See Magnetization transfer ratio (MTR) Mucin 306 Mucin hypersecretion 643 645 Mucocutaneous telangiectasias 1179 Mucopolysaccharides 291 333 Mucor 1566 Mucosal xerosis 375 Mucous-secreting accessory glands 194 Multiacinar necrosis 265 Multidetector row computed tomography (MDCT) 157 Multidrug resistance-1 (MDR1) 1013 Multidrug resistance–associated protein 2 (MRP2) 214 Multifactorial liver disease, role of drugs in 942–943 Multifocal liver metastases 165 Multilamellar vesicles 644 Multilocular anechoic fluid-filled cyst 1245 Multinodular tumor 1255 Multiorgan failure 1549 1561 Multiple cysts, ultrasound image 108 Multiple myeloma 339 Multislice scanners 86 P.I-33 Murine mammary tumor virus (MMTV) 687 Murine schistosomiasis 1365 Murphy's sign 13 Muscle cramps 333 548 Muscle fibers, circular 194 Muscle hypertrophy 519 Muscle pain 1385

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Muscle wasting 369 372 377 Mutants, drug-resistant, risk of 783 Mutations core gene 769 core promoter 769 selection of 769 gene 769–770 PRE-S 770 Myalgia 333 830 831 841 Mycobacteria 284 Mycobacterial infections 1414–1415 Mycobacterial liver abscess 1417 Mycobacterium avium complex (MAC) 1414 1436 epithelioid granuloma 1415 Mycobacterium avium intracellulare 285 in patients with acquired immunodeficiency syndrome 286 Mycobacterium genavense 1415 Mycobacterium kansasii 1415 Mycobacterium tuberculosis (MTB) 1361 1414 1434–1435 Mycobacterium xenopi 1415 Mycophenolate 865 1502 Mycophenolate mofetil (MMF) 690 870 1450 1474–1475 1484 effects of 1474 in liver transplantation 1475 side effects of 1475 use of 1475 Mydriasis 581 Myeloablative therapy 404 Myelodysplastic syndrome 349 351 353 Myelofibrosis with myeloid metaplasia 343–344 Myelogenous leukemia, chronic 349 Myeloid metaplasia 46 344 Myelolipoma 1220 Myelopathy 581 hepatic 581 Myelophthisis 424 Myeloproliferative diseases 425 Myeloproliferative disorder (MPD) 198 349 1539 latent, diagnosis of 422 and liver 352–353 primary 618 Myeloproliferative syndrome 19 Myelosuppression 231 1493 Myocardial hypokinesia 507 Myocardial infarction 39 41 acute 36 detection of 36 Myocardial injury 960 Myofibroblastic tumor 282 Myofibroblasts 395 396

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contraction of 427 Myofilaments 874 Myoglobin 214 Myoinositol 584 585 611 Myopathy 373 Myositis 336 inflammatory 336 Myxedema 329 ascites 333 coma 333

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Copyright ©2007 Lippincott Williams & Wilkins > Back of Book > Index > N

N N-acetylcysteine, infusion 613 932 N-acetyl-m-aminophenol (AMAP) 1010 N-acetyl-p-benzoquinoneimine (NAPQI) 878 961 1009 NAD See Nicotinamide-adenine dinucleotide (NAD) NADPH See Nicotinamide adenine dinucleotide phosphate (NADPH) NAFLD See Nonalcoholic fatty liver disease (NAFLD) N-glycans 53 NAI See NASH activity index (NAI) Naltrexone 895 NAPQI See N-acetyl-p-benzoquinoneimine (NAPQI) Naproxen 503 NAS See NASH activity score (NAS) NASH See Nonalcoholic steatohepatitis (NASH) 95 NASH activity index (NAI) 1120 NASH activity score (NAS) 1120 Nasobiliary tubes 168 NAT See Nucleic acid testing (NAT) National Health and Nutrition Examination Survey (NHANES) 986 National Institute of Health (NIH) 742 835 1518 1530 Natural killer (NK) cells 316 716 815 depletion of 962 Natural killer T (NKT) cells 684 Nausea 831 NCR See Noncoding region (NCR) Necrapoptosis 1012 Necroinflammatory disease acute 261 chronic 246 panacinar 254 Necroinflammatory injury active, with regenerating liver cells 256 chronic 261–270 various forms of 254 Necroinflammatory patterns, acute 254–261 Necrosis 247 253 313 318 608 679 1011 1203 1429 death signaling in 318 degree of 31 multiacinar 265

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periportal 758 spotty, hepatitis-like 280 submassive, acute 262 tubular 612 zonal 937 Needle aspiration 1356 percutaneous 1356 Needle biopsy 245 303 1204 evaluation of 265 Needle biopsy specimen from cirrhotic liver 299 Nefazodone 974 Neisseria 1394 Nelfinavir 951 Neomycin 587–588 593 Neonatal giant cell hepatitis 258 Neonatal hemochromatosis (NH) 1321–1322 1321 Neonatal hepatitis 1064 1077 syndrome of 1331–1335 Neonatal hepatitis/cholestasis, causes of 1331–1335 congenital infections 1331–1334 disorders associated with 1331 Neonatal iron overload 1043 1055 Neonatal sepsis, fulminant 1353 Neoplasia features of 101 noncutaneous 1502 Neoplasm 205 1172 Neoplastic cells 1220 Neoplastic cysts 101 Neoplastic disease 1351 Neovascularization in splanchnic organs 432 Nephrocalcinosis 1034 Nephronophthisis 1241 Nephrotic syndrome 1032 Nephrotoxic drugs 502 direct 612 use of 612 Nephrotoxicity 780 1414 drug-induced 502 prevention of 1477 tenofovir-associated 782 Nerve fibers 194 Nerve stimulation, sympathetic 193 Nerves 193 Neurodegenerative disease 584 Neurohypophysis 499 Neuroimaging 583–585

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conventional 584 standard 578 Neurologic disease 973 1024 1031 1037 drugs used in treatment of 976 Neurologic dysfunction 1085 1484 Neurologic manifestations, improvement of 576 Neuromuscular abnormalities 570 Neuronal dysfunction 570 575 Neuronal excitability 574 Neuropathy 373 Neuropraxia 1521 Neuropsychiatric disease 581 1024 1034 Neuropsychiatric syndrome 569 Neuropsychological impairment 585 Neuroserpin 1072 Neurosteroids 573 575 Neurotensin 193 Neurotoxicity 217 Neurotransmission 574 589 abnormalities of 576 dopaminergic 573 GABAergic 575 glutamate 584 glutamatergic 575 576 sympathetic 403 Neurotransmitter systems 576 multiple abnormalities of 576 Neurotransmitters 574 576 central 589 false 574 inhibitory 574 Neutralizing antibodies 835 Neutropenia 1408 induction chemotherapy–associated 1390 Neutrophil chemoattractant, potent 1069 Neutrophil leukocyte dysfunction 557–558 Neutrophilia 1353 1472 Neutrophilic infiltration 890 P.I-34 Neutrophils 261 271 272 280 1068 1354 1388 Nevirapine (NVP) 950 1406 Newborns, universal vaccination of 751 NH See Neonatal hemochromatosis (NH) Niaspan 954 Nicotinamide adenine dinucleotide (NAD), regeneration of 35 1352 Nicotinamide adenine dinucleotide phosphate (NADPH) 402 NIEC See North Italian Endoscopic club (NIEC)

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Niemann-Pick disease (NPD) 291 292 1141 1315 Nifedipine 952 1140 NIH See National Institute of Health (NIH) Nimesulide 966 Niperotidine 978 Nipradilol 453 Nitric oxide (NO) 430–431 intrahepatic delivery, increasing 449 role of, in modulating intrahepatic vascular resistance 429 synthase inhibitors 453 Nitrofurantoin 940 Nitrogen excretion of 589 urinary elimination of 572 Nitrogen balance 369 Nitrogen intake 369 Nitroimidazoles 1353 Nitrovasodilators 449 NK See Natural killer (NK) NK cells See Natural killer (NK) cells N-methyl-D-aspartate (NMDA) 614 Nocturnal hemoglobinuria, paroxysmal 349 NOD See Nonobese diabetic (NOD) Nodal disease 1272 Nodular 1229–1246 Nodular distortion 1235 Nodular hepatic lesions, needle biopsy of 1236 Nodular hyperplasia 209 Nodular neoplasms 1235–1236 Nodular panniculitis 1129 Nodular regenerative hyperplasia (NRH) 183 202 209 514 927 1229– 1232 1434 1567 conditions associated with 1231 nodules of 1232 unusual forms of 1232 Nodules 1230 large regenerative 1230 Non-Hodgkin's lymphoma (NHL) 9 329 343 1232 and Hodgkin's lymphoma, hepatic manifestations of 342 Non-neoplastic diseases, diagnosis of 251 Non-nucleoside reverse transcriptase inhibitors (NNRTIs) 950–951 hepatotoxicity associated with 1411–1412 Nonabsorbable disaccharides 585–587 Nonacetaminophen 617 Nonacetaminophen drug 606 Nonacetaminophen group, non predictive value (NPV) 617 Nonalcoholic fatty liver disease (NAFLD) 62 93–

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96 320 329 370 698 923 959 1117–1150 1339 1486 animal models of 1134 1135 small 1134 biopsy studies 1133 clinical and laboratory findings in 1128–1130 clinical criteria for 1118–1122 conditions associated with 1125 1140–1141 definitions and terms of 1118 development of 1122 and diabetes 1127 early observations of 1122–1123 endpoints of therapy 1142 epidemiology of 1124–1126 exercise 1142–1145 experimental 1134–1135 genetic factors in 1126–1128 ethnic variation 1126–1127 familial factors 1127 genetic variation 1127–1128 high-risk groups, prevalence in 1124–1126 histologic criteria for 1118–1120 1122 histology scoring system 1132 historic perspective of 1122–1124 imaging in 1130–1131 computerized tomography 1130 elasticity 1130 magnetic resonance imaging 1130–1131 spectroscopy 1130–1131 ultrasonography 1130 industrial agents 1141 initial histology, variation based on 1133 initial intervention of 1142 laboratory abnormalities of 1129 laboratory features of 1128–1129 1128 liver biopsy in, use of 1131–1133 medication induced 1140–1141 mitochondrial changes 1138–1139 mortality overview 1133 natural history of 1133–1134 and normal aminotransferases 1129 pathogenesis of 1135–1140 pharmacologic treatment of 1143 predictors of underlying histology 1131–1132 presumed 1120 prognosis of 1133–1134 radiologic imaging of 1130 signs and symptoms of 1128

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solvents 1141 terminology of 1118–1122 treatment of 1142–1150 Nonalcoholic steatohepatitis (NASH) 93 317 320 330 365 401 403 698 867 889 925 1050 1117 1118 1135– 1140 1486 1548 with cirrhosis 1120 classification and stages of 1121 conditions associated with 1140–1141 as factor in other liver diseases 1126 Ludwig's description of 1123 predictors of more severe histology in 1131 primary 1118 related cirrhosis 1134 secondary 1118 1140–1141 Nonanastomotic strictures 1485 Noncoding region (NCR) 711 Noninfectious granulomas 285–288 Noninvasive imaging, role of 17 Nonobese diabetic (NOD) 687 Nonparenchymal cells, incorporation of 623 Nonsteroidal anti-inflammatory drugs (NSAIDs) 62 298 925 use of 552 Nonstimulated neutrophils 901 Noradrenaline 508 Norepinephrine 501 504 507 613 Norfloxacin 518 559 944 Norfloxacin prophylaxis, long-term 563 North Italian Endoscopic club (NIEC) 444 Novel imaging, technologies of 406 Noxious stimulus, magnitude of 318 NPD See Niemann-Pick disease (NPD) NRH See Nodular regenerative hyperplasia (NRH) NRTIs See Nucleoside reverse transcriptase inhibitors (NRTIs) NS4b, function of 811 NSAIDs See Nonsteroidal anti-inflammatory drugs (NSAIDs) Nuclear glycogenation 330 Nuclear receptor signaling 402–403 Nuclear retinoid receptors 402 Nucleic acid testing (NAT) 746 Nucleocapsid 714–716 808 Nucleophilic attack 224 Nucleoside analogs, development of 1534 Nucleoside reverse transcriptase inhibitors (NRTIs) 950 1403 hepatotoxicity associated with 1411 5'-nucleotidase activity 46–47 during pregnancy 1283

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Nutrient absorption 379 Nutrition 585–586 614–615 and liver 365–384 metabolic and nutritional principles of 366–373 Nutritional assessment 374–377 Nutritional disturbance 612 Nutritional status, body mass index (BMI), classification by 377 Nutritional supplementation 901–902 1146–1147 clinical trials 901–902 rationale for 901 Nutritional therapy 375 380 382 NVP See Nevirapine (NVP)

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O OABP See Organic anion binding protein (OABP) Obesity 330 334 647 843–844 884 957 1124 1127 1489 1493 Obliterative angiopathy 1486 Obliterative hepatocavopathy 1172 1173 Obstructive jaundice 1219 1240 Occlusion 1171 Occlusion balloon catheter 437 Occult cirrhosis 1131 OCG See Oral cholecystography (OCG) OCSs See Oral contraceptive steroids (OCSs) Octopamine 574 Octreotide 453 464–465 507 1260 Ocular melanoma 143 147 Oddi, sphincter of 194 Ofloxacin 944 P.I-35 OGDC See 2-oxoglutarate dehydrogenase complex (OGDC) Oil red-O stain 250 250 OKT3 1476 administration of 1476 side effects of 1476 use of 1477 used for 1477 Okuda staging system 1267 1268 Oligomerization 1073 Oligonucleotides 846 triplex-forming 1078 Oligophrenia 1241 OLT See Orthotopic liver transplantation (OLT) Omeprazole 458 Oncotherapeutic drugs 967 liver injury associated with 968 Oncotic necrosis 313 Ondansetron 690 1097 Onychomycosis 948 superficial 949 Opalski cells 1029 Open reading frame (ORF) 711 739 808

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Open surgery with cyst removal or drainage 1246 Opioids, endogenous 671 Opisthorchiasis 1362 1369–1371 Opisthorchis felineus 1369 Opisthorchis viverrini 1369 Opsonic activity of ascitic fluid 557 decreased 557–558 Optimal biopsy, characteristics of 64 Optimal therapy 1391 OPTN See Organ Procurement and Transplantation Network (OPTN) Oral antibiotic prophylaxis 1482 Oral anticoagulation 522 Oral cholecystography (OCG) 652 Oral contraceptive 954–956 benign neoplasms 955 cholestasis 955 steroids 955 Oral contraceptive steroids (OCSs) 927 Oral contraceptives (OCPs) 647 1201 Oral dissolution therapy 655 Oral hypoglycemic drugs 959–960 Oral nalmefene 690 Oral naltrexone 690 Oral taurine 379 Oral ulcers 1475 Orcein/Victoria blue stains 247 248 ORF See Open reading frame (ORF) Organ Procurement and Transplantation Network (OPTN) 1546 Organic anion binding protein (OABP) 220 Organic anion transporting polypeptides (OATPs) 1012 Organic anions, metabolism of 233–235 Organic nitrates 457 Organogenesis 189 Organomegaly 334 Oriental patients 771 Orlistat (tetrahydrolipostatin) 1145 Ornidazole 1353 Ornipressin 507 Ornithine 51 Ornithine–aspartate 589 Oropharyngeal cancer 1486 1502 Orthotopic liver transplantation (OLT) 321 602 615– 617 905 1023 1024 1055 1217 1240 1297 1484 1490 1545 1546 1560 auxiliary partial patients undergoing 619 right-lobe 619

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use of 619 coagulopathy management in 358–359 clichy criteria 617 conventional 602 cost-effectiveness of 619 King's College criteria 615 living-related, survival rates of 619 selection criteria for 615 Osmium stain for fat 291 Osmium tetroxide 290 Osteoarthrosis, premature 1035 Osteoblastic activity 43 Osteoid tissue 43 Osteomalacia 342 372 671 1029 Osteomyelitis 46 Osteopenia 690 1486 Osteoporosis 372 671 690 1029 1489 1494 Overlap syndrome 668 Oxandrolone 381 Oxidative phosphorylation 1011 Oxidative stress 317 319 322 576 609 611 1010–1011 sepsis-related 612 Oxmetidine 978 2-oxoglutarate dehydrogenase complex (OGDC) 682 Oxygen consumption 613 Oxygen-free radicals, generation of 610

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Copyright ©2007 Lippincott Williams & Wilkins > Back of Book > Index > P

P P13-k/p7056 kinase activation 1470 PAI-1 See Plasminogen activator inhibitor-1 (PAI-1) Pain syndrome 158 PAIR See Puncture, aspiration, introduction of protoscolicidal agent, and reaspiration (PAIR) Pallidal hyperintensity 584 Palmar erythema 698 1282 Palmipedes 1134 Palpable left lobe, presence of 10 Palpation with patient in the right lateral decubitus position 13 PAN See Polyarteritis nodosa (PAN) Pan-caspase inhibitor, IDN-6556 323 Panacinar emphysema 513 Panacinar mitosis 206 Pancreas carcinoma of 423 tumors in, patients with 171 Pancreatic β-cells 370 Pancreatic carcinoma 135 142 Pancreatic disease, chronic 404 Pancreaticoduodenal, inferior 192 Pancreaticoduodenal veins 189 Pancreatitis 141 652 1245 1287 1521 acute 650 biliary 651 chronic 423 gallstone 1293 in pregnancy 1292–1293 Paneth cells 1070 Papilla endoscopic views of 160 tumors in, patients with 171 Papilla of Vater 651 Papillary stenosis 170 1416 Papilloma virus 604 Papillomatosis, biliary 307 Papular acrodermatitis (Gianott-Crosti disease) 759 Paraaminosalicylic acid 41

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Paracentesis 548 1194 large-volume 548 without plasma volume expansion 549 renal function 549 serum creatinine 549 serum electrolytes 549 therapeutic 548–551 total 548 Paramyxoviruses 604 Paraneoplastic syndrome 336 Parasite infection, donor liver 1361 Parasites 285 Parasitic diseases 1359–1373 Parasitic infection 174 agents used to treat 949 Parasympathetic fibers 193 Parasympathetic stimulation 193 Paraumbilical vein 189 Parenchyma 607 collapsed 261 hepatic 138 257 nodular transformation of 425 Parenchymal injury intra-acinar necroinflammatory changes 265 spotty 268 Parenchymal iron deposition 97 Parenchymatous cells 1352 Parenteral amino acids, peripheral 380 Parenteral iron overload 1043 1054 Parenteral nutrition (PN) 1141 associated liver disease 378–380 pathophysiology of 379–380 Parenteral therapy 1355 Parenteral transmission 722 Paresthesias 1093 Parkinsonism, hepatic 581 Paroxysmal nocturnal hemoglobinuria (PNH) 350 353 acute thrombosis in 353 Partial liver graft, methods of evaluation 1517 Partial hepatectomy 1244 Partial nodular transformation (PNT) 1232–1233 Partial thromboplastin time (PTT) 354 Parvovirus B19 604 606 PAS See Periodic acid-Schiff (PAS) PAS pressure See Pulmonary artery systolic (PAS) pressure Passive hepatic congestion 1191–1194 1192 ascites, formation of 1193

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clinical features of 1193–1194 outcome of 1193–1194 pathophysiology of 1192–1193 treatment of 1194 Passive immunoprophylaxis, effectiveness of 1535 Patch venoplasty 1515 Patent ductus venosus (PDV) 145 Pathogen-associated molecular patterns (PAMPs) 814 Patient education 493 PBA See Phenylbutyric acid (PBA) PBC See Primary biliary cirrhosis (PBC) PCLD See Polycystic liver disease (PCLD) P.I-36 PCP infection See Pneumocystis carinii (PCP) infection PCR See Polymerase chain reaction (PCR) PDC See Pyruvate dehydrogenase complex (PDC) PDC-E2 See Pyruvate dehydrogenase complex-E2 (PDC-E2) PDGF See Platelet-derived growth factor (PDGF) Peak cortisol levels 618 Pediatric end-stage liver disease (PELD) 1511 1455 Pediatric patients 1126 PEG See Percutaneously inserted gastrostomy (PEG) Peginterferon 1404 Pegylated interferon 707 1407 and ribavirin, dosing guidelines for combination therapy with 840 PEI See Percutaneous ethanol injection (PEI) PELD See Pediatric end-stage liver disease (PELD) Peliosis 302 1180 Peliosis hepatis 200 297 298 941 955 970 985 1172 1180 1215 bacillary, causative agent of 1172 imaging reports of 1180 treatment of 1180 PEM See Protein-energy malnutrition (PEM) Pemoline 976 Penicillamine 966 1024 1033 1035 1036 1294 1296 Penicillin 607 1440 Pentamidine 1361 aerosolized 1484 Pentapeptide neodomain 1070 Pentoxifylline 507 875 879 900 900 clinical trials of 900 rationale for 900 Pentoxyphylline 408 409 PEPCK See Phosphoenolpyruvate carboxykinase (PEPCK) Peptic ulcer 1210 Peptic ulcer disease 891 Peptides, thymic-derived 784

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Percutaneous abscess drainage 150–151 Percutaneous biopsy 61 66 109 Percutaneous cyst aspiration 1240 Percutaneous drainage 127 1372 use of 1372 Percutaneous ethanol injection (PEI) 1259 for hepatocellular carcinoma (HCC) 1271 Percutaneous liver biopsy 62–65 336 complications of 64–65 contradictions to 62 ultrasonographic guidance of 63 Percutaneous puncture 66 128 Percutaneous transhepatic cholangiogram (PTC) 656 1242 1499 Percutaneous transhepatic cholangiography (PTHC) 127 133–136 136 indications for 133 Percutaneously inserted gastrostomy (PEG) 383 Perforin 1470 Peribiliary chloroma 1567 Peribiliary glands 195 Peribiliary plexus 198 Pericardiectomy 1195 Pericarditis 337 1369 constrictive 532 Pericellular fibrosis 819 Pericholangiolar inflammation 1386 Pericholangitic 258 Pericholecystic fluid 652 Periductal fibrosis 275 Periductal plexus, capillaries of 189 Periductular fibrosis 407 Perinatal transmission 829–830 Periodic acid-Schiff (PAS) 247 1103 1313 after diastase digestion 248 256 positive globules 290 Peripheral arterial vasodilatation hypothesis 543 Peripheral edema 519 549 Peripheral nerves 370 Peripheral parenteral nutrition (PPN) 381 Peripheral vasodilatation 432 Peripheral-type benzodiazepine receptor (PTBR) 573 activation of 575 Periportal fibrosis 1173 Periportal hepatocytes 1077 1192 Perisinusoidal fibrosis 985 1076 Perisinusoidal lipocytes See Ito cells Perisinusoidal stellate cells 183 Peristomal varices 673

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bleeding of 673 Peritoneal friction rub 13 Peritoneal–venous shunt 552 1194 complication of 552 Peritoneum 137 Peritonitis 702 bacterial 70 tuberculous 70 532 Peritransplantation 905 nutritional support of 382–384 Perivenular fibrosis 890 Permeability transition pore (PTP) 318 Peroxisomal metabolism 1140 Peroxisome proliferator-activated receptor (PPAR) 402 1135 Peroxynitrite 317 Pestiviruses 809 PET See Positron emission tomography (PET) PFIC See Progressive familial intrahepatic cholestasis (PFIC) PFIC See Progressive familial intrahepatic cholestasis type 3 (PFIC 3) PFIC-2 See Progressive familial cholestasis type 2 (PFIC-2) PGs See Prostaglandins (PGs) Phagocytic cells 314 Phagocytosis 1354 1438 Phalloidin 36 Pharmaceutical industry 1016–1017 Pharmacologic therapy in portal hypertension 440 Pharmacologic treatment response, monitoring 457 Phencyclidine 977 Phenelzine 974 Phenindione 954 Phenobarbital 603 977 Phenobarbital therapy 234 Phenothiazines 1440 Phenprocoumon 954 Phenylalanine 33 382 574 Phenylbutazone 876 Phenylbutyrate 589 Phenylbutyric acid (PBA) 1078 oral administration of 1078 Phenylethanolamine 574 Phenytoin 47 603 929 971–1440 PHES See Psychometric hepatic encephalopathy score (PHES) PHG See Portal hypertensive gastropathy (PHG) clinical course of 448 risk factor 448 Phlebotomy 98 1052 1085 1102 Phlebotomy therapy 1042

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Phosphatidylcholine 641 642 Phosphatidylinositol glycan A (PIG-A) 353 Phosphodiesterase inhibitors 522 Phosphoenolpyruvate carboxykinase (PEPCK) 1306 Phospholipase A 2 542 Phospholipidosis 292 876 pathogenesis of 953 Phosphomannomutase (PMM) 1314 Photocutaneous lesions 1085 Photosensitivity in erythropoietic protoporphyria (EPP) 1103 Phrenic arteries, inferior 192 Physioanatomic considerations of liver 183–210 Phytosterolemia 380 Picornaviruses 711 Piecemeal necrosis 264 268 PIG-A See Phosphatidylinositol glycan A (PIG-A) Pigment storage 288 Pigmentation, hepatic 234 Pioglitazone 330 959 1149 Piperacillin 614 Piroxicam 965 PIs See Protease inhibitors (PIs) Pit cells 200 PIZZ See Protease inhibitor ZZ (PIZZ) PLA See Pyogenic liver abscess (PLA) Placenta 187 Placental alkaline phosphatase 44 Placental phosphatase, influx of 43 Planar scintigraphy 1213 Plane abdominal radiographs 1210 Plant sterols (phytosterols) 380 Plasma albumin 24 Plasma antidiuretic hormone level of 546 Plasma bilirubin 223 Plasma bilirubin concentration measurement of 223–225 normal ranges 225 Plasma bilirubin turnover (BRT) 223 Plasma exchange 623 Plasma lipoproteins 370 Plasma proteins 366 Plasma radiobilirubin 230 Plasma renin activity 501 550 560 vs. systemic vascular resistance 550 before and after therapeutic paracentesis 549 Plasma separation system 623

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Plasma thromboplastin component (PTC) 104 Plasma volume expansion of 432 increased 432 Plasma volume expansion 560 patients undergoing, care of 550 Plasmapheresis 620 690 1037 1106 Plasmin activity 399 P.I-37 Plasminogen activator inhibitor-1 (PAI-1) 1561 Plasmodium falciparum 1359 Plasmodium malariae 1359 Plasmodium ovale 1359 Plasmodium vivax 1359 Platelet defects 612 Platelet-derived growth factor (PDGF) 398 401 downstream pathways of 401 induction of 401 transgenic expression of 401 Platelets 400 401 Platypnea 514 Pleural effusion 533 1353 Pleuritis 337 1369 Plexogenic arteriopathy 519 PMM See Phosphomannomutase (PMM) Pneumococcal pneumonia 9 Pneumococcal vaccine 1494 Pneumocystis carinii (PCP) infection 945 1483 Pneumocystis pneumonia 1416 Pneumonia 612 1383 1437 Pneumonitis 1387 Pneumoperitoneum 70 Pneumothorax 65 137 PNF See Primary nonfunction (PNF) PNH See Paroxysmal nocturnal hemoglobinuria (PNH) Polarizing microscopy 252 Polyacrylamide, plasma isoelectric focusing of 1066 Polyamine spermine, precursor of 51 Polyarteritis nodosa (PAN) 336 758 HBV-related 758 Polyclonal antibodies 1476 administration of 1476 lymphoproliferative disorders, posttransplant 1476 side effects of 1476 Polyclonal hyperglobulinemia 889 Polycystic disease adult 302 303 1219

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infantile 301 302 Polycystic kidney disease 108 course of disease 1236–1237 epidemiology of 1236–1237 Polycystic liver with massive enlargement of liver 1239 Polycystic liver disease (PCLD) 165 1229 1236–1241 clinical features of 1238 complications of 1238–1240 fluid-filled cysts of 1238 genetics of 1238 laparoscopic surgery for 1240 molecular biology of 1238 pathology of 1238 treatment of 1240–1241 Polycystic ovary syndrome 1128 Polycystin-1 1238 Polycythemia rubra vera 1172 Polycythemia vera (PV) 349 352 424 Polydipsia 1290 Polyethylene glycol (PEG) 838 Polymerase chain reaction (PCR) 252 533 707 733 813 1379 1430 based fecal test 1369 Polymyalgia rheumatica 1209 Polymyositis 336 1255 Polyneuropathy, progressive mixed chronic 339 Polypeptide chain binding protein family 1073 Polyunsaturated fatty acids (PUFA) 1140 Polyuria 1290 Polyvinyl alcohol (PVA) 143 POPH See Portopulmonary hypertension (POPH) Porcelain gallbladder 651 Porcine 624 Porphobilinogen (PBG) deaminase activity 1091 deficiency of 1085 erythrocyte 1097 monopyrrole 1086 Porphyria cutanea tarda (PCT) 1097–1103 1296 biochemical evaluation of 1098 cutaneous lesions of, chronic renal failure, patients with 1103 disorders associated with 1098 hepatic crystals in 1101 and hepatitis C 1098 relationship between 1098 and HFE mutations 1098 liver damage in 1085 1099–1102 long-standing, hepatocellular carcinoma 1101

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management in 1102–1103 photocutaneous lesions in 1099 porphyria mimicking 1098 skin lesions in 1099 sporadic 1091 Porphyrias 253 1085–1109 1296 acute 1092–1097 biochemical abnormalities in 1089–1092 1090 clinical manifestations of 1085 1086 clinical features of 1092 δ-aminolevulinic acid dehydrase deficiency 1106 diagnosis of 1089 and drugs 1094 dual 1107 hepatocellular carcinoma in 1097 hepatoerythropoietic 1107 neurologic dysfunction, acute attacks of, associated with 1086 types of 1106–1107 variegate 1092 Porphyric attack 1092 acute 1085 1096 clinical features of 1093–1094 management of 1095–1097 pathogenesis of 1095 prevention of 1097 in women 1093 biochemical evaluation of 1094 erythropoietin, treatment with 1097 signs and symptoms of 1093 Porphyrins 291 excretion of 1086 1089 structures of 1087 Porphyrin precursors, excretion of 1089 Porphyrinogenic drug 1095 Porphyrinogens 1087 Porphyrinuria, secondary 1085 1086 1089 1107–1108 1107 Porta hepatis 136 185 Portacaval shunt 53 130 interposition 489 side-to-side 489 489 Portacaval shunt procedure, end-to-side 489 Portal biliopathy 422 Portal cavernoma 422 portal biliopathy 422 transhepatic stenting of, percutaneous 423 Portal circulation 192 Portal decompression 488

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mesocaval shunts 1178 Portal fibroblasts 398 Portal fibrosis 344 352 949 noncirrhotic 425 Portal flow, maintenance of 489 454–456 advanced stages of 430 angiogenic process, VEGF-dependent 432 classification of 424 clinical consequences of 442–448 clinical significance of 436 clinical–hemodynamic correlations in 448 complications of 431 686 1567 associated with 424 development of 425 625 1238 diseases causing, classification of 421 drug combination 453 endocannabinoids, role for 430 endoscopy 435–436 etiology of 421–426 422 idiopathic 425 etiology of 425 liver 425 portacaval anastomosis 425 variceal bleeding 425 imaging techniques 434–435 intrahepatic 425 causes of 424–426 and leakage of fluid 534–537 management of, surgical methods 488–492 myofibroblasts, contraction of 427 natural history and clinical manifestations of 442–448 nitric oxide inhibitors 430 noncirrhotic 207 421 941 and nonsurgical management 419–475 pathophysiology of 426–432 schematic representation of 427 pharmacologic treatments of 451 postsinusoidal and prehepatic, transmicrovascular fluid exchange in 534–535 prehepatic 421 423 447 cause of 421 presinusoidal 1233 prostaglandins 431 serum/ascites albumin gradient 532 sinusoidal 505 surgical management of 485–493 anatomy of 486–487

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evaluation of 487–489 history of 485–486 pathophysiology of 487 P.I-38 symptomatic 1242 toxicity 425 treatment of 432 variceal wall tension 433 Portal hypertension in rats intestinal capillary pressure 536 intestinal lymph flow 536 portal blood flow 536 portal vein pressure 536 Portal hypertensive gastropathy (PHG) 421 437 447 treatment of 474–475 Portal hypertensive syndrome 442 posthepatic 426 prehepatic 421–424 Portal infiltrate 1536 Portal inflammation 261 819 956 1483 chronic with lymphoid 263 Portal macrophages 253 Portal perfusion, maintenance of 490 Portal pressure measurement of 132 436–439 direct 436 indirect 437 reducing 451 Portal repermeation 423 Portal thrombosis, idiopathic 425 Portal tract inflammation 949 Portal triads 196 Portal trunk 189 Portal vein (PV) 184 189–190 190 486 atresia of 190 cavernous transformation of 190 conductance of 205 congenital absence of 190 congenital stenosis of 423–424 embolization of 150 extrinsic compression of 424 internal roots of 199 intrahepatic 131 loss of 93 magnetic resonance image 435 preduodenal 190 spectral doppler tracing of 86

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stricture 140 thrombosis 349 ultrasonographic examination of 424 venographic imaging of 129 Portal vein embolization (PVE), transhepatic 143 150 Portal vein flow 439 Portal vein hypertension 353 Portal vein obstruction, hemodynamic abnormalities 423 Portal vein thrombosis (PVT) 421 625 1186 acute 423 diagnosis of 423 angiography 423 chronic, diagnosis of 422 cirrhosis 422 computed tomographic (CT) scan 422 diagnosis of 422 direct thrombolytic therapy 423 magnetic resonance imaging (MRI) 422 postoperative 699 prothrombotic systemic conditions, associated with 422 Portal venography 129–132 437 Portal venous pressure 487 Portal venous anatomy 486 486 changes of 487 Portal venous system 1386 anomalies of 190 Portal venous thrombosis 491 Portal–collateral circulation 431 Portal–systemic collaterals 426 Portal–systemic shunts 370 role of 493 Portography arteriographic 130 limitations of 130 transabdominal-transhepatic 131–132 132 transabdominal-transsplenic 132 transvenous 130–131 Portoportal interposition bypass graft shunt 423 Portopulmonary hypertension (POPH) 493 513 519–523 520 clinical features of 519–520 complications of 522 definition of 519 diagnostic approach to 521 epidemiology of 519 evaluation for 520–522 histologic features of 519 medical treatment for 522

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natural history of 522 pathogenesis of 519 pathology of 519 prognosis of 522 symptoms of 519 therapy for 522–523 treatment with vasodilators 522 Portosystemic collateral circulation 431–432 Portosystemic encephalopathy (PSE) 365 582 Portosystemic shunts 193 226 455–456 519 569 570 578– 580 584 590 592 842 1124 1239 congenital 591 extrahepatic 569 occlusion of 594 partial 489–490 490 patients with 594 total 489–490 disadvantage of 489 pathophysiology of 489 transjugular intrahepatic 498 Positron emission tomography (PET) 88–91 147 1207 advantages of 90 fluorine-labeled 2-deoxy-2 glucose (FDG) 1267 patient information 91 scanning 103 Post–liver transplantation 970 long-term causes of death 1491 Postembolization syndrome 1260 Postoperative jaundice 697 Postpolycythemic myeloid metaplasia (PPM) 352 Postthrombocythemic myeloid metaplasia (PTM) 352 Posttransfusion hepatitis 29 827 risk of 827 Posttransplant lymphoproliferative disease (PTLD) 1343 1565 Posttransplantation 508 844–845 Posttransplantation diabetes (PTDM) 1485 Posttransplantation therapy 267 Posttreatment biopsy 1149 Povidone-iodine (Betadine) 67 PPAR See Peroxisome proliferators activated receptor (PPAR) PPM See Postpolycythemic myeloid metaplasia (PPM) PPN See Peripheral parenteral nutrition (PPN) Pravastatin 954 Praziquantel 1367 Prazosin 428 450 453 Pre-eclampsia, hematologic manifestations of 354 PRE-S/S regions 769

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Pre-SIRT angiography, meticulous 147 Prealbumin 365 377 Prebiopsy anxiolysis 64 Precipitating factors elimination of 591–592 management of 592 Predictable hepatotoxicity, mechanisms of 1006–1009 Predictable liver toxins 1005 Predictable toxicity, idiosyncratic, relevance of 1014–1015 Prednisolone 689 690 899 Prednisolone monotherapy 869 Prednisone 340 869 1471 cessation 1472 use of, long-term 1472 Prednisone priming, role of 772 Preeclampsia 1281 symptoms of 1290 with HELLP syndrome, disorders of 1283 Preeclampsia liver disorders 1287–1289 Pregnancy 647 1498–1499 acute fatty liver of 426 complicated by hyperemesis gravidarum 1285 computed tomography 1284 unintended 1498 in women, with chronic liver disease 1294–1297 Pregnenolone 575 Preneoplastic lesions, putative 300 Presynaptic neurons 575 Pretransplant antiviral therapy 1530 Pretreatment biopsy 75 Primary biliary cirrhosis (PBC) 246 272– 275 322 334 425 679 939 1295–1296 1426 1439 1486 1495 1536 1548 associated syndromes 685 autoantibodies 682 characteristic laboratory abnormalities of 682 complications of 685–686 diagnosis of 272 686 687–688 epidemiology of 680 680 genetics of 680–681 680 with granuloma 1439 initial descriptions of 691 liver histologic abnormalities in 684 natural history of 691 overlap syndromes 685 pathogenesis of 686–687 pathology of 683–684 physical findings of 681 681

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prognosis of 691 routine laboratory tests of 681–682 symptoms of 681 681 syndromes, associated 685 treatment of 688–691 689 P.I-39 Primary graft nonfunction (PNF) 1482 1493 1546 risk factors for 1482 Primary hepatic pregnancy 1283 Primary hyperoxaluria type 1 (PH-1) 1459 liver–kidney transplants 1459 Primary liver cancer 1253 Primary sclerosing cholangitis (PSC) 102 103 158 275 275 322 334 665–674 683 1191 1310 1328– 1329 1434 1439 1486 1495 1536–1538 1548 abnormalities of 668 advanced stages, symptoms of 668 animal model 667 biochemical testing 668 clinical features of 668 complications of 671 management of 672–673 conditions that mimic during cholangiography 167 diagnosis of 102 165 665 668 669 1537 diagnostic criteria for 669–670 670 differential diagnosis 669–670 diseases, associated with 667 671 endoscopic retrograde cholangiopancreatography (ERCP) 668 669 epidemiology of 665–666 etiology of 667 genetic factors 666–667 genetic polymorphisms, associated with 666 heterogeneity of 667 histologic staging of 669 imaging studies 668–669 immunologic testing 668 inflammatory bowel disease (IBP), association of 671 672 laboratory findings 668–669 liver biopsy 669 liver transplantation 674 1537 magnetic resonance cholangiopancreatography (MRCP) 668 management of 671–674 medical therapy 674 674 overlap syndrome 668 pathogenesis of 666–668 666 hypotheses 667–668 pathogenetic role in 667

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patients with 171 recurrent, diagnosis of 1537 setting of 159 small-duct 668 670 surgical therapy 674 survival of, transplant-free 670 susceptibility genes in 667 vitamin replacement therapy for 672 Primate cells 730 Primer hybridization 822 Proapoptotic proteins 317 divisions of 317 Probiotics 906 Procainamide 953 1440 Procapsids 712 Procedural shunts 579 Proctocolectomy 671 Prodromal symptoms 343 Progenitor cell, bipotential 189 Progesterone metabolism, abnormalities of 1286 Prognostic models, meta-analysis of 1461 Prognostic risk score 1273 Progressive familial cholestasis type 2 (PFIC-2) 1322 Progressive familial intrahepatic cholestasis (PFIC) 231 237 645 1322– 1323 Progressive familial intrahepatic cholestasis type 3 (PFIC 3) 1286 Progressive fatigue 519 Progressive liver dysfunction 1077 Proinflammatory cytokines 611 1354 Proliferation 401 Propafenone 953 Prophylactic phenytoin 614 Prophylaxis 492 561–563 pharmacologic 456 Propylthiouracil 956 Propofol 159 613 Propranolol 453 1097 nonresponders to 457 oral 474 portal pressure–reducing effect of 453 Propylthiouracil (PTU) 333 902 904 clinical trials of 902 904 rationale for 902 Prostacyclin 522 542 infusion of 613 Prostaglandin E 2 542 Prostaglandin G 2 , endoperoxides 542

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Prostaglandin H 2 542 Prostaglandins (PGs) 193 370 431 499 542 renal synthesis of 542 Prostaglandin synthesis 542 Protease activity 811 Protease inhibitors (PIs) 289 951 1406 hepatotoxicity associated with 1412 Protease inhibitor ZZ (PIZZ) 1321 Proteasomal inhibitors 1075 Proteasome 1075 Protectin 353 Protein 2 289 367 614 multidrug resistance–associated 22 Protein calorie malnutrition 904 Protein-energy malnutrition (PEM) 365 373–377 creatinine–height index 377 diagnosis of 374 history of 375 immune competence 377 physical examination of 375 primary 373 secondary 373 serum albumin concentration 375–376 serum prealbumin concentration 377 Waterlow classification of 377 Protein-energy malnutrition (PEM) syndrome, characteristics of 373 Protein metabolism 367–369 Protein restriction 365 Proteinuria 1033 1288 Proteoglycans 200 396 399 401 Proteolytic destruction 1068 Proteolytic enzyme 47 Proteome 1016 Proteomics 406 Prothionamide 946 Prothrombin 49 51 373 Prothrombin complex 357 Prothrombin time (PT) 51–53 354 factors involved in quick one-stage test 52 progressive shortening of 52 prolonged 52 Proton pump inhibitors 979 Protoporphyria cutaneous lesions in 1104 erythropoietic 1103 liver damage in 1085 liver disease in 1105

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protoporphyrin metabolism in 1104 Protoporphyrin 1089 1103 bone marrow 1103 deposits of 254 293 enterohepatic circulation of 1104 erythrocyte 1106 excretion of, mechanism of 1089 liver damage 1105 neurotoxic effect of 1106 photosensitivity 1103 secretion of, into bile 1089 Protoporphyrin metabolism in protoporphyria 1104 Protoporphyrinogen 1090 Protoporphyrinogen IX 1087 Protozoa 285 Protozoal diseases 1359 Protozoal infections 1416 Pruritus 7 8 681 688 690 831 938 1064 1281 1285 1439 cholestatic 671 pathogenesis of 671 management of, medications used for 671 Prussian blue stain 248 249 270 PSC See Primary sclerosing cholangitis (PSC) PSE See Portosystemic encephalopathy (PSE) Pseudoalbinism 373 Pseudoaneurysms 143 Pseudocirrhosis 1234 Pseudogene 1065 Pseudolipoma 1221 Pseudopodia 200 Pseudoporphyria 1085 1108–1109 immunofluorescence 1108 Pseudotranscription initiation codon 1065 Pseudotumor, inflammatory 282 284 Pseudotumor cerebri 372 Pseudoxanthomatous change 272 Psoralens plus ultraviolet A therapy 1109 Psoriasis 337 968 970 pathogenesis of 337 Psychiatric disease, atypical 1031 Psychiatric symptoms 841 Psychometric hepatic encephalopathy score (PHES) 582 PT See Prothrombin time (PT) PTBR See Peripheral-type benzodiazepine receptor (PTBR) PTDM See Posttransplantation diabetes (PTDM) PTHC See Percutaneous transhepatic cholangiography (PTHC) PTLD See Posttransplant lymphoproliferative disease (PTLD)

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PTM See Postthrombocythemic myeloid metaplasia (PTM) PTP See Permeability transition pore (PTP) PTT See Partial thromboplastin time (PTT) PTU See Propylthiouracil (PTU) PUFA See Polyunsaturated fatty acids (PUFA) P.I-40 Pulmonary angiography 515 Pulmonary artery systolic (PAS) pressure 520 Pulmonary capillary wedge 613 Pulmonary disease, patients with 1268 Pulmonary dysfunction 513 Pulmonary edema 1287 Pulmonary function tests 514 Pulmonary granulomatosis 1441 Pulmonary hypertension 516 519 520 522 in hepatic schistosomiasis 1368 Pulmonary microvasculature 513 dilatation in 523 Pulsus paradoxus 19 Puncture, aspiration, introduction of protoscolicidal agent, and reaspiration (PAIR) 1246 Purulent meningitis 558 Putative toxins 571–574 576 PV See Portal vein (PV) PVA See Polyvinyl alcohol (PVA) PVE See Portal vein embolization (PVE) PVT See Portal vein thrombosis (PVT) Pyelonephritis 702 Pylephlebitic abscess 282 Pyloric veins 189 Pyogenic abscess 282 Pyogenic liver abscess (PLA) 1353–1356 1355 amebic liver abscess (ALA) vs 1354 1355 aspiration and drainage 1356 bacteriology of 1355 clinical manifestations of 1354 diagnosis of 1354 endoscopic drainage 1356 epidemiology of 1353–1354 frequency of 1353 imaging of 1355 laboratory 1355 microbiology 1355 pathogenesis of 1354 risk factors for 1351 surgery for 1356 surgical drainage 1356

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therapy for 1355–1356 Pyrazinamide 947 1013 1383 Pyrimethamine 1334 Pyrimethamine–sulfadoxine (Fansidar) 949 Pyrrolizidine alkaloids 984–985 Pyruvate dehydrogenase complex (PDC) 322 682 Pyruvate dehydrogenase complex-E2 (PDC-E2) 1560

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Copyright ©2007 Lippincott Williams & Wilkins > Back of Book > Index > Q

Q Q fever 284 1387–1388 1429 1437 causative rickettsia of 1387 doughnut granuloma of 1388 hepatic manifestations of 1387 typical presentation of 1387 QF score See Quantity frequency (QF) score QTL See Quantitative Trait Locus (QTL) Quality of life (QOL) 1490 Quantitative Trait Locus (QTL) 645 Quantity frequency (QF) score 887 Quasispecies 813 Quinidine 953 1440 Quinine, oral administration of 548 Quinolone prophylaxis, long-term 563 Quinolone-resistant bacteria 563

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Copyright ©2007 Lippincott Williams & Wilkins > Back of Book > Index > R

R RA See Rheumatoid arthritis (RA) RAAS See Renin-angiotensin-aldosterone-system (RAAS) Rabeprazole 979 Radiation therapy 1260 Radioactive particle embolization, inadvertent 147 Radiofrequency ablation (RFA) 147 149 1214 1270–1271 Radiographic findings 520 Radioimmunoassay 29 Radionuclide lung perfusion scanning 516 Radionuclide scanning 652 655 Radionuclides, regional distribution of 585 Ramipril 951 Randomized controlled trials (RCTs) 1259 Rapamycin 409 1451 1471 1475–1476 1502 1506 adverse effects of 1475 in liver transplantation 1475 side effects 1475 Rapid plasma reagin (RPR) 1386 1431 Rapid viral response (RVR) 838 implications of 841 RAPS4 (Rapid Alcohol Problems Screen) 4 887 Ras-Raf-MAP kinase 1470 RBCs See Red blood cells (RBCs) RCTs See Randomized controlled trials (RCTs) Reactive lysis, membrane inhibitor of 353 Reactive metabolite 1006 1016 central role of, in drug-induced liver injury 1006 formation of 1016 generating, enzymes involved in 1009 hepatotoxicity 1010–1012 safe elimination, enzymes involved in 1009–1010 screening 1016 target for, role of mitochondria 1011–1012 Reactive metabolite syndrome (RMS) 929 Reactive oxygen species (ROS) 216 316 884 1011 ethanol-driven generation of 317 Receiver operator characteristics (ROC) 71 Receptor-interacting protein (RIP) 316

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Rechallenge deliberate 933 inadvertent 933 Recidivism 895 1452 Recombinant antigen immunoblot assay (RIBA) 819 Recombinant factor VIIa (rFVIIa) 357–358 potential benefit of 358 Recurrent liver disease 1525 autoimmune 1525 1536–1539 following liver transplantation 1525–1540 1526 Red blood cells (RBCs) 349 350 99m

Tc pertechnetate-labeled 1213

peripheral 351 transfusion 359 REE See Resting energy expenditure (REE) Reed-Sternberg cells 342 Refractory ascites therapy for 552 management of, peritoneovenous leveen shunt, vs. therapeutic paracentesis 552 transjugular intrahepatic portacaval shunt (TIPS), Vs. paracentesis 554 Refsum's disease 1140 Regeneration 254 Regenerative nodular hyperplasia 1192 Regenerative nodules 1218 1236 Regional lymphadenitis 1437 Regulatory protein, p62 280 281 Rejection in liver transplant recipients, evidence of 1471 Relapsing polychondritis (RP) 335–336 Reactive metabolite syndrome 927 Relaxin 409 Remission 869 failure of 869 induction of 869 maintenance of 869 Renal cell carcinoma 344 Renal circulation vasoconstriction of 497 Renal complications 497–509 clinical features of 498–504 Renal dialysis 604 Renal dysfunction 498 503 506 1236 1485 1504–1506 1505 development of 1504 Renal dysplasia 1241 Renal failure 338 377 502 503 505 614 870 930 960 1450 acute 1504

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calcineurin-induced renal 1486 diuretic-induced 548 incidence of 614 oliguric 1482 prerenal 502 Renal function 508 pathogenesis of 505–506 Renal hemodynamics 505 Renal hypoperfusion 542 Renal impairment 497 612 1489 development of 560 Renal insufficiency 1150 1481 1493 Renal medulla 370 Renal perfusion 507 impairment of 551 maintenance of 542 Renal toxicity 1483 Renal transplant 1494 Renal transplantation 1237 Renal tubular acidosis (RTA) 503 Renal tubular epithelium 1238 Renal vasoconstriction 497 501–503 505–509 542 development of 529 pathogenesis of 501 pharmacologic therapy of 507–508 prevention of 506–507 Renal-sparing agent 1450 Rendu-Osler-Weber syndrome 424 1179 computed tomography, contrast-enhanced 1179 Renin 504 507 Renin-angiotensin-aldosterone-system (RAAS) 499 546 Renin–angiotensin system 544 activation of 450 541 561 blockade of 450 Reovirus type 3 667 P.I-41 Repaglinide 960 Reperfusion injury 1481 Replacement therapy 1078 Replicase 812 RES See Reticuloendothelial system (RES) Resectional therapy 1355 Respiratory failure acute 1187 postoperative complications of 1493 Resting energy expenditure (REE) 366 Restriction fragment length polymorphism (RFLP) 768

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Reticulin fibers 200 Reticulin stain 247 299 Reticuloendothelial (RE) cells 20 1041 1426 hepatic 54 Reticuloendothelial cell function in cirrhosis 556 Reticuloendothelial system (RES) 92 215 1438 depression of 556–557 phagocytic activity 557 impairment of 556 Retinoid loss 402–403 Retinoid X receptor (RXR) 643 Retinoids natural and synthetic 985–986 potential utility of 410 Retinol 371 Retinyl esters 371 402 Retransplantation 1540 1545 1546 cause of death following 1549–1551 early indications for 1547 incidence of 1546 indications for 1546–1547 late indications for 1547–1548 and living donor liver transplantation 1552 and MELD score 1552 outcomes in hepatitis C virus patients 1549 predictors of mortality after 1551 vs. primary transplantation 1549 rate of 1546–1547 results of 1549–1552 role of 1545–1553 survival after 1551–1552 timing of 1549 Retrograde wedged hepatic venography 423 Reverse transcriptase-polymerase chain reaction (RT-PCR) 787 821 Reye's syndrome (RS) 279 928 930 938 953 972 1141 1291 1319 RFA See Radiofrequency ablation (RFA) RFLP See Restriction fragment length polymorphism (RFLP) rFVIIa See Recombinant factor VIIa (rFVIIa) Rhabdomyolysis 977 1381 acute 41 Rhabdomyosarcomas 1172 RHC See Right-sided heart catheterization (RHC) Rhesus monkeys 371 Rheumatic diseases 334–337 collagen vascular disorders 334 myositis 336 relapsing polychondritis (RP) 335–336

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rheumatoid arthritis (RA) 335 systemic lupus erythematosus (SLE) 334–335 Rheumatic disorders 329 Rheumatoid 968 Rheumatoid arthritis (RA) 335 816 871 930 970 1442 juvenile 335 monitoring hepatotoxicity in patients with, guidelines for 970 Rheumatologic diseases, analgesics and drugs used to treat 960–967 Rhizopus 1566 ρ-nitrophenylphosphate 42 Rhodanine stain 248 249 Ribavirin 707 837 840 841 843 845 1053 1294 1407 1409 Ribonucleic acid (RNA) 605 709 711 729 human intestinal 1070 single positive-stranded polyadenylated 739 single-stranded 807 Ribonucleic acid interference (RNAi) therapy 323 Ribozymes 783 Rickettsia 284 Rickettsial infections 1387–1388 Riedel's lobe 185 Rifampicin 603 947 1383 1384 Rifampin 671 1013 Rifamycin SV 231 Rifaximin 588 Right hepatic venogram 133 Right-sided heart catheterization (RHC) 519 Riluzole 976 RIP See Receptor-interacting protein (RIP) Ritonavir 951 RMS See Reactive metabolite syndrome (RMS) RNA See Ribonucleic acid (RNA) RNA interference (RNAi) 783 RNAi therapy See Ribonucleic acid interference (RNAi) therapy ROC See Receiver operator characteristics (ROC) Rocky mountain spotted fever 1388 Rodents, cocaine toxicity in 204 Rofecoxib 966 Rogers' cirrhosis 1361 ROS See Reactive oxygen species (ROS) Rosiglitazone 330 959 1149 Rotor's syndrome 27 54 227 231 234–237 clinical and laboratory findings of 234 genetic defects of 235 patients with 234 phenotypic features of 232 treatment of 237

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Round ligament 185 Roux-en-Y anastomosis 133 Roux-en-Y choledochojejunostomy 170 Roux-en-Y cyst jejunostomy 1244 Roux-en-Y hepaticojejunostomy 171 1244 1499 1519 Roxithromycin 946 RP See Relapsing polychondritis (RP) RPR See Rapid plasma reagin (RPR) RS See Reye's syndrome (RS) RT-PCR See Reverse transcriptase-polymerase chain reaction (RT-PCR) RTA See Renal tubular acidosis (RTA) Rue hepatic encephalopathy 1188 RXR See Retinoid X receptor (RXR)

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Editors: Schiff, Eugene R.; Sorrell, Michael F.; Maddrey, Willis C. Title: Schiff's Diseases of the Liver, 10th Edition Copyright ©2007 Lippincott Williams & Wilkins > Back of Book > Index > S

S S-adenosyl-methionine (SAMe) 904–905 1147 clinical trials of 905 rationale for 904–905 Salicylates 24 62 965–966 Salmonella enteritidis 1380 Salmonella hepatitis (typhoid fever) 1380–1381 clinical presentation of 1381 diagnosis of 1381 liver histology of 1381 Salmonella paratyphi 1380 Salmonella typhi 1380 Salmonella typhimurium 1380 Salmonellosis 282 Salvia miltiorrhiza 409 Sarcoid granulomas 425 1433 Sarcoidosis 46 273 277 285 287 329 340–342 425 533 688 1425 1431– 1434 1439 1442 chronic cholestatic syndrome of 277 hepatic 341 341 425 with multiple noncaseating epithelioid granulomas 1434 pancreatic 341 patients with 287 therapeutic options for 1434 Satellitosis, neutrophilic 280 SBP See Spontaneous bacterial peritonitis (SBP) Scanning electron microscopy 252 Scar matrix, degradation of 410 Scarred livers 200 SCD See Sickle cell disease (SCD) Scheuer system, florid duct lesion stage 683 Schistosoma hematobium 1363 1363 Schistosoma intercalatum 1363 1363 Schistosoma japonicum 1363 1363 Schistosoma mansoni 1363 1363 egg granuloma in liver 1364 Schistosoma mekongi 1363 1363 Schistosomal liver disease 1363 liver fibrosis 1367 Schistosomes 1362 human 1363 1367 species of 1363 Schistosomiasis 286 424–425 1360 1363–1368 1431 1436–1437 1437 advanced hepatic 1365 bacterial infections associated with 1366 clinical manifestations of 1365–1366

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diagnosis of 1367 ELISA method 1367 disease mechanisms 1363–1364 granuloma cells 1365 growth retardation, children with 1366 hepatic fibrosis 1364 liver disease 1364 murine 1365 with sinusoidal portal hypertension 131 therapy for Schistosoma mansoni infection 1367 P.I-42 medical 1367 surgical 1367–1368 and viral hepatitis 1366–1367 SCIC See Sickle cell intrahepatic cholestasis (SCIC) Scientific Registry of Transplant Recipients (SRTR) 1470 1545 Scintigraphy 109 110 Scleral icterus 8 226 Scleroderma 336 448 685 cutaneous 336 Sclerosing agents 458 Sclerosing cholangitis 45 56 135 165–166 166 195 primary 6 206 867 1032 secondary 278 670 Sclerosing hemangioma 307 Sclerosis 1240 Sclerotherapy 486 492 complications of 458 endoscopic 486 Screening colonoscopy 1128 SE See Spin-echo (SE) SEC See Sinusoidal endothelial cell (SEC) SEC receptor See Serpin–enzyme complex (SEC) receptor Secondary amyloidosis (AA) 339 causes of 339 Secondary sclerosing cholangitis 670 Sedative hypnotics 974 Selective hepatic angiography showing large hepatocellular carcinoma 1260 Selective internal radiation therapy (SIRT) 127 148 complications of 147 Selective serotonin reuptake inhibitors (SSRIs) 974 Selective shunts 490 Selenium 373 Self-expanding metal stents (SEMS) 161 173 SEN virus 606 Sengstaken-Blakemore tube 454 Sennomotokounou 985 Sensitizers 173 Sepsis 332 612 1518 1521 1564 bacterial 704 fungal 704 Septal fibrosis 53 Septic shock 607

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Septicemia 612 Septum transversum 187 1305 Serologic markers, noninvasive panels of 61 Seronegative hepatitis 618 Seronegative polyarthritis 337 Serotonin 574 Serpins 1063 1066 Serpin–enzyme complex (SEC) receptor 1070 Sertraline 690 Serum enzyme activity in 43 preliminary incubation of 46 Serum albumin 365 Serum albumin concentration 375–376 Serum albumin level 15 Serum alkaline phosphatase 43 values at various ages for men 43 clinical methods of determination 43 Serum aminotransferase 1481 1485 Serum bile acid levels 30 Serum bilirubin 26 45 378 668 chromatogram of 25 diagnostic value of 23–26 fractionation of 26 measurement of 22–24 26 van den Bergh method 22 Serum bilirubin levels 704 Serum enzyme tests 34 Serum ferritin levels 1050 Serum glutamate dehydrogenase 41 Serum glutamic-oxaloacetic transaminase (SGOT), activities of 37 Serum hepatitis 808 Serum iron studies 1053 Serum markers limitations of 406 of matrix molecules/modifying enzymes 405–406 Serum opsonic activity 556 Serum prealbumin concentration 377 Serum proteins 49–50 Serum retinal, concentration of 372 Serum sickness 758 Serum to ascites albumin gradient (SAAG) 1193 Sevoflurane 701 958 Sexual transmission 829 Shifting dullness, assessment of 14 Shigella 1394 Shock liver 1187 Short interfering RNA (SiRNA) 783 hepatitis B virus (HBV) deoxyribonucleic acid vaccination 784 S and pre-S antigen vaccines 784 T cell vaccines 784 synthetic administration of 784 Short-term stenting 166

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Shunt dysfunction 553 1177 Shunt occlusion 552 Shunting, intracardiac 516 Sicca syndrome 690 Sickle cell anemia 5 648 Sickle cell disease (SCD) 329 337–339 350 704 acute hepatic syndromes associated with 338 hepatic dysfunction in 352 hepatic histologic findings in 352 patients with 337 338 Sickle cell hepatopathy 351 Sickle cell intrahepatic cholestasis (SCIC) 337 Sickle hepatic crisis, acute 352 Sickling 338 Sieve plates 196 Signal amplification 822 Signal transducers and activators of transcription (STAT) 1470 Silencing complex, RNA-induced 784 Silibinin 607 Silybum marianum 408 Silymarin 408 690 846 906 Simple cyst 108 Simple hepatic cyst 84 1241 Simvastatin 954 Single nucleotide polymorphism (SNP) 681 1127 Single photon emission CT (SPECT) 1206 Sinusoidal capillarization 53 Sinusoidal damage, evidence of 620 Sinusoidal dilatation 296 297 1173 panacinar 297 periportal 298 Sinusoidal endothelial cell (SEC) 313 Sinusoidal fibrosis 298 Sinusoidal lesions 297–298 Sinusoidal lumen 1354 Sinusoidal macrophages 183 Sinusoidal obstruction syndrome (SOS) 403 930 1557 1561–1562 before hematopoietic cell transplantation (HCT), risk factors for 1561 diagnosis of 1562 prevention of 1562 risk factors for 1561 Sinusoidal portal hypertension 530 Sinusoidal sickling 337 Sinusoidal wall 200 Sinusoids 183 187 196–198 258 capillarization of 198 fibrosis of 298 hepatic 196 220 1187 thrombosis of 298 ultrastructure of 197 siRNA See Small interfering ribonucleic acid (siRNA) Sirolimus 971 SIRS See Systemic inflammatory response syndrome (SIRS) Sister Mary Joseph's nodes 15

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Sitaxsentan 522 980 Sitosterolemia 642 Situs inversus 1307 Sjögren's syndrome 336 683 685 688 1439 Skin, chronic 1103 Skin cancer 1486 Skin excoriation 8 Skin hyperpigmentation 681 Skin lesions in porphyria 1107 SLA/LP See Soluble liver antigen and liver–pancreas (SLA/LP) SLE See Systemic lupus erythematosus (SLE) SMA See Superior mesenteric artery (SMA) Smads 402 Small cell dysplasia 834 Small duct sclerosing cholangitis 165 Small interfering ribonucleic acid (siRNA) 321 Small intestine transplantation, survival data for 381 Small intestinal obstruction 552 Smart stent 138 Smooth muscle antibodies (SMAs) 866 940 Smooth muscle hyperplasia 1204 Snover's triad 276 SNP See Single nucleotide polymorphism (SNP) SNS See Sympathetic nervous system (SNS) SOD See Sphincter of Oddi dysfunction (SOD) Sodium chloride, intravenous administration of 554 Sodium restriction 546 Sodium retention 497–499 506 540 546 intensity of 498 Sodium taurocholate cotransporting polypeptide (NTCP) 1012 Sodium valproate 1291 Sodium-retaining effect 546 Soft tissue hematoma 356 P.I-43 Solid lesion 108 Soluble liver antigen and liver–pancreas (SLA/LP) 866 Somatosensory 583 Somatostatin 163 193 452 464 518 analogs of 453 Sonography 84 conventional 85 real-time compound 85 Sorbitol dehydrogenase 41 activity of 41 SOS See Sinusoidal obstruction syndrome (SOS) Space of Disse 198 198 199 397 1192 Sparse ganglion cells 194 Special patient groups, treatment in 842–846 SPECT See Single photon emission CT (SPECT) Spectrophotometry 27 224 Spherocytes 351 Sphincter dilatation 164 Sphincter manometry 158 Sphincter of Oddi dysfunction (SOD) 158

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classification of 158 type II 158 type III 158 Sphincteroplasty 655 Sphincterotome 159 160 Sphincterotomy 158 174 655 1351 bleeding 163 endoscopic 65 651 656 Sphingolipids 290 Sphingomyelin 642 Spider angiomata 9 514 1282 Spider telangiectasis 698 Spin-echo (SE) 97 SPIO See Superparamagnetic iron oxide (SPIO) Spirochetal infections 1385–1387 Spironolactone 457 546 952 Spironolactone metabolite receptor 547 Spironolactone metabolites 547 Splanchnic arterial vasodilatation 497 529 545 Splanchnic blood volume, manipulation of 453–454 Splanchnic circulation 189 505 disturbance in 506 Splanchnic hyperemia 430 487 Splanchnic lymph formation 545 Splanchnic organs, neovascularization in 432 Splanchnic vasodilatation 430–432 Splanchnic vasodilatation systemic arteriolar 610 Splanchnic vasodilator peptides, release of 452 Spleen palpation of 10 12 percussion of 11 Splenectomy 343 485 schistosomiasis, with esophagogastric devascularization in 1368 Splenic artery 1512 angiography 423 Splenic infarction 625 Splenic puncture 53 Splenic vein 189 486 obstruction 423 Splenic vein thrombosis 423 causes of 423 Splenomegaly 67 335 337 340 350 424 485 522 607 681 698 756 1174 1221 1232 1257 1365 1366 causes of 12 Splenorenal shunt, distal 491 Split allograft, implantation of 1515 Split-liver transplantation 1511 Spontaneous bacterial peritonitis (SBP) 497 502 555–563 clinical characteristics of 558 community-acquired 560 development of 561 probability of 557 558 563 risk of 563 diagnosis of 555 558

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diagnostic paracentesis 558 effect of systemic antibiotics on 561 hepatorenal syndrome (HRS), type of 1 560 hospital-acquired 560 iatrogenic factors 558 in cirrhosis 556 intravenous albumin, infusion in 559 560 laboratory and microbiologic data 558 liver transplantation 555 management of 559 oral antibiotics 559 effectiveness of 559 parenteral antibiotics 559 pathogenesis of 555–558 555 presence of 558 prevalence of 555 prophylaxis of, intestinal decontamination, long-term 561 due to quinolone-resistant bacteria 563 recurrence, probability of 562 renal impairment in 561 resolution of, predictors of 560–561 predictors of survival 560–561 treatment of 559–560 variceal bleeding 560 Spontaneous cyst rupture 1245 Sporadic hepatitis 830 Sporadic transmission 829 Sporothrix schenckii 1415 Spotty necrosis 265 Spur cells 349 351 hemolytic anemia 351 SQUID See Superconducting quantum interference device (SQUID) SR See Sustained release (SR) SREBP See Sterol regulatory element–binding protein (SREBP) SRTR See Scientific Registry of Transplant Recipients (SRTR) Stable zonation 203 Staining methods 246 Starvation 367 STAT See Signal transducers and activators of transcription (STAT) Stauffer's syndrome 19 344 Steatohepatitis 279 282 334 369 378 379 938 942 1117 1121 1124 1129 1134 1140 1145 1441 alcoholic 938 alcoholic hepatitis and nonalcoholic 279–282 drugs associated with 936 diseases with features of 281–282 drug-induced 938 mechanism of 1137 nonalcoholic 281 708 823 942 1121 1254 with pericellular (“chicken-wire”) fibrosis 283 tamoxifen-induced 1140 Steatonecrosis 1360 histologic findings of 75 Steatorrhea 672

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Steatosis 74 86 97 278– 279 330 334 335 374 378 403 889 890 1117 1119 1121 1128 1133 1135 1150 1401 benign 704 classification 278 degrees of 94 hepatic 365 374 401 843 of liver 1291 macrovesicular 278 279 associated with 278 microvesicular 278 279 279 1119 causes of 279 hepatocytes with 279 risk factors of 1413 simple 1119 total parenteral nutrition (TPN)-induced, mechanism for 704 Stellate cells 196 198–200 396 398 399 401–403 409 986 activation of 200 400–403 400 407 408 inhibit 408–409 initiation 400–401 perpetuation of 401–403 transcriptional regulation 403 apoptosis of 410 chemotaxis of 401 contractile stimulus for 402 contractility of 402 fibrogenesis 403 hepatic 397 398 activation of 395 plasma membrane receptor 403 proinflammatory responses of 409–410 proliferation of 403 Stellate scar 1203 Stem cell transplantation 625–627 Stenosis 424 488 Stent placement 166 Stent removal 168 Stenting 138–140 in hepatobiliary disease 139–140 Stents, polytetrafluoroethylene-coated 1177 Step-care approach 547 Stereoisomerization 217 Steri-Strips 68 Steroid 772 Steroid bolus 1482 Steroid hormones 370 Steroid monotherapy 869 Steroid refractory rejection 1483 1538 Steroids 1484 androgenic/anabolic 297 Sterol regulatory element–binding protein (SREBP) 1135 Stevens-Johnson syndrome 945 964 Stibogluconate 1361 Stomatocytes 349 351 Stone extraction 165

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Storage 288 copper 293 crystals 293 fibrinogen 304 P.I-44 glycogen 289 pigment 288 Storage disease, hepatic 231 235 Storage products, identification of 288–293 Streptomyces hygroscopicus 1475 Streptomyces tsukubaensis 1474 Stroma 200 connective tissue 200 Stromal collagen 200 Stromelysin 666 Strongyloides stercoralis 1416 Subcapsular hematoma 64 Subcutaneous emphysema 70 Submassive necrosis 261 Succinylacetone 1108 Sucralfate 458 Suction needle 62 Sulfadiazine 1334 Sulfobromophthalein sodium (BSP) 26–27 220 prolonged infusion of 27 retention of 27 structural formula for 27 Sulfonamides 24 1440 Sulfotransferases, gene families 1009 Sulfur colloid scan 110 Sulindac 503 964 Sulphate excretion 371 Superconducting quantum interference device (SQUID) 98 99 Superior mesenteric artery (SMA) 1512 Superparamagnetic iron oxide (SPIO) 1206 Surface glycoprotein 731 Surgical decompression 492 Surgical therapy 1213 1356 Sustained release (SR) 954 Sustained viral clearance rates (SVRs) 720 Sustained virologic response 838 1407 1530 clinical implications of 842 of pegylated interferon 1409 SVRs See Sustained viral clearance rates (SVRs) Swollen glia 1029 Symmers fibrosis 1364 portal tracts in 1365 Symmetrical lipomatosis 1141 Sympathetic fibers, unmyelinated 193 Sympathetic nervous activity 544 Sympathetic nervous system (SNS) 499 activation of 546 Symptomatic cysts, management of 1241 Symptomatic infection 731

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Syncope 519 Syncytium 574 Syndecan 396 Syndromic recognition 933 Synergistic theory 571 Synthetic dysfunction, hepatic 1185 Synthetic retinoids 986 Syphilis 1386 1437 clinical manifestations of 1386 Syphilitic hepatitis 1386 Systemic antibiotics 150 Systemic chemotherapy 1260 Systemic circulation 369 Systemic disease 150 Systemic hemodynamics 506 Systemic hyperkinetic syndrome 432 Systemic hypertension, treatment of 453 Systemic hypoperfusion 204 Systemic hypotension 1185 Systemic infection 1379–1394 1415 Systemic inflammatory response syndrome (SIRS) 611 cause of 612 mediators of 611 Systemic lipotoxicity 1135 Systemic lupus erythematosus (SLE) 334–335 929 hepatic involvement in 334 successful treatment of 335 Systemic malignancy 967 Systemic mastocytosis 344 344 Systemic vasoconstrictors with plasma expansion 507 Systemic vasodilators 501 Systolic murmur 520

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Editors:


C. Title:


Copyright ©2007 Lippincott Williams & Wilkins > Back of Book > Index > T

T T cells, innate 817 T-lymphocyte response CD4 + 817 CD8 + 817–818 TACE See Transarterial chemoembolization (TACE) Tachycardia 137 375 1093 Tacrolimus 865 870 1272 1474 1486 1495 1497 1560 action, mechanism of 1474 with cyclosporine, efficacy and safety of 1474 in liver transplantation 1474 side effects of 1474 neurotoxic 1474 Talc microcrystals 1441 Tamoxifen 956 TAO See Triacetyloleandomycin (TAO) Tarcine 975 Target amplification methods 822 Target cells 349 Tasosartan 952 Taurine 371 641 Taurine-conjugated chenodeoxycholic acid (TCDC) 322 Tay-Sachs disease 1141 Tazobactam 614 TB See Tuberculosis (TB) TBG See Thyroxine-binding globulin (TBG) TCDC See Taurine-conjugated chenodeoxycholic acid (TCDC) 99m

Tc sulfur colloid scintigraphy 1206 1217

TDEE See Total daily energy expenditure (TDEE) Technetium-99 sulfur colloid liver scan 1233 1235 Technetium-99m 1204 Telangietactic FNH (TFNH) 1235 Telbivudine 717 TELV See Total estimated liver volume (TELV) Tenascin 200 Tenofovir 781–782 1403 1535 Tenofovir disoproxil fumarate 781 Terbinafine hepatotoxicity 949 Terlipressin 452 464 507 508 613

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effects of 508 Terminal hepatic venules 196 Testicular atrophy 9 Tetrabamate (atrium) 977–978 Tetracycline 1384 Tetracycline toxicity 1291 Tetrapyrroles 1086 Tetrathiomolybdate 1024 1036 TFA See Trifluoroacetylated (TFA) TFNH See Telangietactic FNH (TFNH) TFR2 See Transferrin receptor 2 (TFR2) TGF-α See Transforming growth factor-α (TGF-α) TGF-β See Transforming growth factor-β (TGF-β) TGF-β antagonists 409 Thalassemia 704 828 1563 β-thalassemia 1054 Thalidomide 906 Therapeutic paracentesis 548–552 Therapeutic phlebotomy 1051 1052 in porphyria cutanea tarda (PCT) 1054 Therapeutic program, design of 593–594 Therapy, pathophysiologic basis of 448–475 TheraSpheres 148 Thiazolidinediones (TZDs) 409 958–959 1118 1147–1149 1148 comparison of 1148 troglitazone 958–959 risk factors for 958 6-Thioguanine 971 Thiopentone 613 Thorotrast deposition 97 Thrombectomy, surgical 1482 1547 Thrombin 51 Thrombocythemia 349 1172 Thrombocytopenia 8 66 137 336 349 353 380 522 612 833 1290 1389 1408 1558 dilutional 353 drug-induced 353 in liver disease 353–354 Thrombocytopenic purpura 353 Thrombocytosis 353 Thrombolytic agents 143 Thrombolytic therapy 143 Thrombolytics 1176 Thrombophilia, hereditary 1172 Thrombophlebitis 1096 1255 Thrombosis 192 356 488 1210 1213 hemostatic basis for 356

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mesenteric vein 143 portal vein 143 1513 Thrombotic diathesis 353 Thrombotic occlusion of hepatic veins, cause of 1172 Thrombotic thrombocytopenic purpura–hemolytic uremic syndrome (TTP-HUS) 353 Thromboxane 370 Thromboxane A 2 (TXA 2 ) 428 Thymosin 784 Thyroid disease 332 688 Thyroid disorders 329 Thyroid hormones 332 Thyroid replacement therapy 333 Thyroid storm 332 Thyrotoxicosis 329 333 Thyroxine-binding globulin (TBG) 1314 Tick-borne disease 1388–1389 laboratory and clinical manifestations of 1389 Ticlopidine 965 Ticrynafen 952 TIMPs See Tissue inhibitor of metalloproteinases (TIMPs) Tin protoporphyrin 1097 P.I-45 Tinidazole 1353 TIPS See Transjugular intrahepatic portosystemic shunt (TIPS) Tissue anoxia 149 Tissue eosinophilia 981 1433 Tissue epithelioid histiocytes 1426 Tissue harmonic imaging 84 85 Tissue hypoxia 942 Tissue inhibitor of metalloproteinases (TIMPs) 399 Tissue injury 1063 Tissue plasminogen activator (TPA) 143 356 1561 TJLBx See Transjugular liver biopsy (TJLBx) TMP/SMX See Trimethoprim-sulfamethoxazole (TMP/SMX) TNF See Tumor necrosis factor (TNF) TNF receptor–associated protein 2 (TRAF-2) 316 TNF-α See Tumor necrosis factor-α (TNF-α) TNM See Tumor-node-metastasis (TNM) TNM staging system 1272 Tobacco 1255 Tolbutamide 231 Tolcapone 976 Tolcapone hepatotoxicity 976 Tolerance, induction of 1468 Toluidine blue stain 250 Tongue protrusion 580

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Topiramate 973 Toremifene 956 Total daily energy expenditure (TDEE) 366 Total estimated liver volume (TELV) 150 Total iron-binding capacity (TIBC) 890 Total paracentesis 548 Total parenteral nutrition (TPN) 379 648 704 1141 1313 1327 1564 associated liver disease, treatment of 380 cholecystitis, acalculous 705 indication for 704 management of 1564 withdrawal of 704 Total urinary nitrogen (TUN) 369 Toxic liver injury, herbal remedies and dietary supplements 983 Toxic metabolites, production of 1009 Toxic shock syndrome 272 Toxicity 425 Toxins decreasing production of 588–589 factors favoring the effects of 578–580 precipitating factors 578–579 Toxocara canis 1438 Toxoplasmosis 1436 1438 TPA See Tissue plasminogen activator (TPA) TPGS See D-α-tocopheryl polyethylene glycol succinate (TPGS) TPN See Total parenteral nutrition (TPN) Trace metals 373 Trace PBG kit 1094 TRAF-2 See TNF receptor–associated protein 2 (TRAF-2) TRAIL See Tumor necrosis factor–related apoptosis-inducing ligand (TRAIL) Trans-sulfuration 904 Trans-sulfuration pathway 371 Transabdominal biopsy 127 136 Transabdominal liver biopsy 137 risks of 137 Transabdominal splenoportography 127 Transabdominal-transhepatic portography 131–132 132 Transabdominal-transsplenic portography 132 Transaminitis 924 Transarterial chemoembolization (TACE) 127 143 144 1257 1260 1273 necrosis 1274 Transarterial embolization 1214 Transcatheter embolization 131 therapeutic 143 Transcatheter endovascular embolization 1219 Transcription 714

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Transcription-mediated amplification (TMA) 821 Transfer ribonucleic acid (tRNA) 866 Transferrin receptor 2 (TFR2) 1041 mutations of 1048 Transferrin saturation (TS) 1042 Transforming growth factor-α (TGF-α) 207 Transforming growth factor-β (TGF-β) 519 1136 Transfusion, risk of 746 Transfusion-transmitted virus (TTV) 606 1405 fulminant hepatic failure (FHF), development of 606 Transhepatic portosystemic shunt, formation of 130 Transhepatic puncture 150 151 Transhepatic tract, postbiopsy embolization of 137 Transient bacteremia 65 Transient bacterial colonization 649 Transient elastography (FibroScan) 61 72 Transient friction rub 13 Transient neonatal hypertyrosinemia 1315 Transient respiratory insufficiency 625 Transitional cells 398 Transjugular biopsy 127 Transjugular catheterization of portal vein 437 Transjugular hepatic vein catheterization 61 Transjugular intrahepatic portacaval shunt (TIPS) 552–553 limitations of 553 in liver disease 1177 Transjugular intrahepatic portosystemic shunt (TIPS) 129 140– 143 437 455–456 455 467 471–473 486 488 488 508– 509 579 673 1172 1231 1189 1194 endoscopic control therapy, randomized clinical trials 472 473 placement 488 role of 488 519 Transjugular intrahepatic puncture 132 Transjugular liver biopsy (TJLBx) 65–66 137–138 138 preference over percutaneous approach 66 major complications after 66 Transmethylation 904 Transplantation 828–829 hepatocyte 625–627 living-related 619–620 1499 right lobe 620 medications, pregnancy categories for 1499 postrenal, clinical course 760 related complications 1499–1506 stem cell 625–627 Transplanted patient, long-term care of 1489–1506 Transthoracic Doppler echocardiography 520

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Transthoracic echocardiography 516 Transthyretin 1459 Transvenous biopsy 136 Transvenous portography 130–131 Trauma 143 171 358 367 Trazodone 974 Treatment failure 869 Treprostinil 522 Triacetyloleandomycin (TAO) 1009 Triclabendazole 1369 Tricuspid regurgitation 520 Trientine 1036 1296 Trifluoroacetylated (TFA) 934 Triglycerides 379 adipose tissue 367 hepatic 379 water-insoluble 366 Trimethoprim-sulfamethoxazole (TMP/SMX) 1416 1483 tRNA See Transfer ribonucleic acid (tRNA) Troglitazone hepatotoxicity, onset of 959 Trophozoites 1352 Tryptophan 382 574 Tryptophan pyrrolase 1095 TTP-HUS See Thrombotic thrombocytopenic purpura–hemolytic uremic syndrome (TTP-HUS) TTV See Transfusion transmitted virus (TTV) Tuberculosis (TB) 46 930 1381–1384 1383 1425 1429 hepatic 1381 manifestation of 1382 Tuberculous hepatitis 1435 Tuberculous peritonitis 71 Tubular proteinuria 1029 Tubular reabsorption 222 Tularemia 1384 early diagnosis and management of 1384 Tumor ablation 127 percutaneous needle-directed 148–150 Tumor infiltration 1567 Tumor ischemia 1260 Tumor marker for hepatocellular carcinoma (HCC) 112 use of 103 Tumor necrosis factor (TNF) 207 314 667 884 inhibitor 667 Tumor necrosis factor-α (TNF-α) 398 514 666 716 866 1136 1470 circulating levels of 618 plasma concentrations of 623

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Tumor necrosis factor (TNF-β) 1470 Tumor necrosis factor receptor (TNFR) 1012 P.I-46 Tumor necrosis factor receptor 1 (TNFR1) 315 316 320 receptor signaling 316 Tumor necrosis factor receptor 2 (TNFR2) 315 316 Tumor necrosis factor–related apoptosis-inducing ligand (TRAIL) 315 316 410 Tumor shrinkage 146 Tumor-like lesions 1220–1221 Tumor-node-metastasis (TNM) 1257 1268 Tumors 302–307 biliary 304–307 hepatocellular 302–304 radiofrequency ablation 1270 vascular 307–308 vascular channels 302 TUN See Total urinary nitrogen (TUN) Two-signal hypothesis 1469 TXA 2 antagonists 428 Type 2 diabetes mellitus 329 1125 Typhoid fever 1381 Typhoid nodules 1381 Tyrosine 382 574 Tyrosinemia 1095 1141 1459 hereditary 1078

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Copyright ©2007 Lippincott Williams & Wilkins > Back of Book > Index > U

U UCB See Unconjugated bilirubin (UCB) UCP See Uncoupling protein (UCP) UDCA See Urosdeoxycholic acid (UDCA) UDP See Uridine diphosphate (UDP) UDP glucuronyltransferases (UGTs) 1009 UDP-GT See Uridine diphosphate glucuronyl transferase (UDP-GT) UGT1 gene complex 221 Ulex europaeus agglutinin 196 Ultrasonography 63 65 72 187 651 1202 1210 1213 1215 1219 1220 1222 1246 1253 1353 1355 1390 abdominal 338 development of 1256 disadvantages of 106 intravenous contrast agents, microbubble 85 prebiopsy 106 standard 1204 transabdominal 164 652 Ultraviolet (UV) microscopy 253 Ultraviolet A tanning beds 1109 Umbilical fissure 184 185 Umbilical vein 184 185 189 487 obliterated 185 Umbilicus, laparoscopic site of 68 Unconjugated bilirubin (UCB) 639 Unconjugated hyperbilirubinemia, causes of 26 Uncoupling protein (UCP) 1136 Underimmunosuppression 1473 Unfolded protein response (UPR) 316 Unfractionated heparin 953 United Network for Organ Sharing (UNOS) 1273 1417 1449 1490 1529 1548 Universal vaccination 747 of newborns 751 UNOS See United Network for Organ Sharing (UNOS) Untranslated region (UTR) 810 Upper gastrointestinal endoscopy 891 UPR See Unfolded protein response (UPR) Urea 369 Urea synthesis 366 Uremia 41 377 1484 Uridine diphosphate (UDP) 1412 Uridine diphosphate glucuronosyltransferase (UDP-GT) 1317 Uridine-5′-diphosphate-glucuronosyltransferase (UGT) 866 1009 Urinalysis 19 Urinary bilirubin 26 Urinary coproporphyrin 235 excretion of 233 235 Urinary excretion 35 589

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Urinary lithotripsy 655 Urinary sodium excretion 500 Urinary tract sepsis 612 Urine urea nitrogen (UUN) 369 Urobilin 22 Urobilinogen 22 222 1094 Uroporphyrin 1089 1099 1102 in hepatobiliary diseases 1108 Uroporphyrin crystals 291 in hepatocytes 291 needle-like 253 Uroporphyrinogen decarboxylase activity 1086 deficiency of 1107 erythrocyte 1098 Ursodeoxycholates 642 Ursodeoxycholic acid (UDCA) 323 380 408 654 674 679 923 932 1287 1146 1536 use in cholestasis 703 Ursodiol, use of 166 UUN See Urine urea nitrogen (UUN) Uveitis 1431

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Copyright ©2007 Lippincott Williams & Wilkins > Back of Book > Index > V

V Vaccination 836–837 Vaccines 769 1493–1494 Vagal stimulation 194 Val-D-Cytosine (Telbivudine) 782 Valine 382 574 Valproic acid (VPA) 929 972–973 clinical features of 972 973 laboratory findings for 972 973 management of 973 onset of 972–973 outcome of 973 pathology of 973 prevention of 973 risk factors for 972 Valsartan 952 van den Bergh method 22 Vancomycin 588 Vanishing bile duct syndrome (VBDS) 939 drugs associated with 937 Vapreotide 453 465 Variants deficiency 1067 dysfunctional 1067 normal allelic 1066 null allelic 1066–1067 precore 767–769 Variceal bleeding 425 432 488 1368 1434 acute 492–493 primary therapy 492 treatment, recommended approach 467 cause of 432 in cirrhosis 462 control of new trends 493 controlling 489 endoscopic control of 1368 episode 446 evaluation 493 hepatic venous pressure gradient 433

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incidence of cirrhosis patients 445 management of 454 485 491 492 management strategies for 492–493 prehepatic portal hypertension 422 preventing 459 recommendations for prophylaxis of 459–461 461 in schistosomiasis 1368 survival of 447 Variceal decompression, selective 486 Variceal hemorrhage 425 1267 erosion theory 433 esophageal 377 1064 explosion theory 433 high portal pressure 433 pathophysiology of 432–435 treatment of somatostatin 452 Variceal obliteration 458 Variceal obturation 458 Variceal pressure (VP) measurement of 440–442 454 455 Variceal rebleeding prevention of 493 recommendations for 473 schematic representation of 474 survival probability 449 recommendations for treatment of 467–468 Variceal wall tension 432 factors determining 434 Varicella-zoster virus (VZV) 604 723 1560 1565 Variegate porphyria 1090 1091 1092 Vascular bed of cirrhotic livers 428 passive 439 Vascular cell adhesion molecule-1 (VCAM-1) 684 Vascular diseases of liver 1171–1181 Vascular disorders 295–298 drug-induced 941 Vascular endothelial cell growth factor (VEGF) 398 Vascular lesions 941 Vascular obstruction acquired 185 mechanism of 209 Vascular plexus, peribiliary 195 Vascular resistance intrahepatic 426 modulating carbon monoxide, role of 429

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nitric oxide, role of 429 Vascular shear stress 519 Vascular thrombosis 149 Vascular tumors 307–308 Vasculature, hepatic 183 188 Vasculitis, necrotizing 519 Vasoactive regulator 216 Vasoactive systems, and cardiovascular function, chronologic changes of 543 Vasoconstriction 523 systemic 452 Vasoconstrictive effect, splanchnic 431 Vasoconstrictor substances 542 Vasoconstrictors 427 452 507 increased production of 427–428 splanchnic 451 497 use of 509 P.I-47 Vasodilatation 506 intrapulmonary 513–517 517 progressive intrapulmonary 517 splanchnic 506 Vasodilator substances 542 Vasodilators 427 hepatic, insufficient release of 429–430 intrarenal synthesis of 507 peptides 507 portal–collateral circulation, resistance in 450 Vasopressin 452 453 463–464 507 613 Vasopressor agents 613 Vasovagal hypotension 65 VBDS See Vanishing bile duct syndrome (VBDS) VDAC See Voltage-dependent anion channel (VDAC) Vegetable protein 382 VEGF See Vascular endothelial cell growth factor (VEGF) Vein invasion, portal 145 Vein puncture, femoral 132 Veins of Retzius 192 Vena caval anastomosis, infrahepatic 1513 Venesection therapy 372 Veno-occlusive disease (VOD) 99 246 296 426 607 930 1334 1171 1173 1173 diagnosis of 99 hepatotoxic agents 1173 herbal teas, ingestion of 1173 senecio alkaloid toxicity, associated with 297 Venography 1172

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hepatic 138 Venous access 62 Venous angioplasty in hepatobiliary disease 139–140 Venous catheterization, hepatic 132 Venous distention, jugular 520 Venous hypertension, pulmonary 522 Venous occlusion, venography 1180 Venous outflow block, features of 607 Venous outflow obstruction 99 296–297 hepatic 514 results in 296 Venous subendothelial infiltration 1483 Venous thrombosis 336 426 941 Venovenous hemofiltration 509 Venovenous shunts 143 Verapamil 952 1485 Veress needle 67 and trocar 67 67 Very low density lipoprotein (VLDL) 642 816 Vesicles multilamellar 641 unilamellar 641 Victoria blue stain 250 Viral antigens, immunostaining for 251 Viral cytopathicity, direct 819 Viral deoxyribonucleic acid synthesis 715 Viral error catastrophe 838 Viral genotype interferon and ribavirin dosing according to 839 sustained virologic response, influence of 839 Viral hepatitis 5 25 36 204 321 331 334 398 688 702 707 942 1323– 1327 1402 acute 257 337 1292 complications of 258 in pregnancy 1292 fulminant 425 acute icteric 707 ballooning in 1136 bilirubin level 702 blood transfusions 6 cholestatic, synonyms for 258 chronic 396 707 708 natural history of 708 cirrhosis in 72 developments in 710 postoperative 702 recurrent 1525 1528–1536

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subsiding phase of 257 symptom of 5 type A 6 type B 6 Viral hepatitis B, chronic 823 Viral hepatitis C, chronic, coexistence of 823 Viral heterogeneity 814 Viral infection 885–886 1414 Viral infectivity 722 Viral nonresponders 845–846 Viral nucleocapsid 715 Viral relapsers 845 Viral ribonucleic acid, measurement of 821–823 Viremia 1565 chronic 831 Virtual cholangiography 164 Virus 284 strains with precore mutations 266 Virus replication 809–812 Visceral arteriogram 147 Visceral arteriovenous malformations 1179 Visceral larva migrans 285 1438 Visceral leishmaniasis 1360 1438 clinical manifestations of 1361 1362 diagnosis of 1361 in Kupffer cells 1360 Visceral protein synthesis 365 Vitamin A supplementation 690 Vitamin D 686 Vitamin D deficiency 1495 Vitamin E 901 Vitamin E supplementation 1146 Vitamin K absorption of 355 deficiency of 355 treatment with 355 Vitamins 371 A 371–372 toxicity of 372 B 371 deficiency of, assessment of 376 D 372 E 372 fat-soluble deficiency 671 K 372 deficiency of 372 Vitronectin 200

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VLDL See Very low density lipoprotein (VLDL) VOD See Veno-occlusive disease (VOD) Voltage-dependent anion channel (VDAC) 318 von Hippel-Lindau 108 von Meyenburg complex 300 301 301 1218 1219 1242–1243 1243 VPA See Valproic acid (VPA) VZV See Varicella-zoster virus (VZV)

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Copyright ©2007 Lippincott Williams & Wilkins > Back of Book > Index > W

W Wall tension (WT) 432 Wallstent 138 139 Warfarin (Coumadin) 1194 Warfarin overdose 358 Warm reperfusion (WR) 321 Warthin-Starry silver staining 249 1417 1438 Water retention in cirrhosis, pathogenesis of 554 solute-free 499–501 506 pathogenesis of 499 WBC See White blood cells (WBC) Weber-Christian disease 1129–1130 Wedged hepatic vein pressure (WHVP) 424 437 measurements of 437 portal pressure (PP) 438 Wedged retrograde portography 435 Weibel-Palade bodies 200 Weight gain 1149 1493 Weight loss 378 647 830 1221 1386 in children 1145 supplements for 1145–1146 Weight-reduction surgery 1146 Weil disease 1385 Wernicke's encephalopathy 1285 Wernicke-Korsakoff encephalopathy 590 White blood cells (WBC) chemoattraction 403 WHO See World Health Organization (WHO) WHV See Woodchuck hepatitis virus (WHV) WHVP See Wedged hepatic venous pressure (WHVP) Wilson disease 97 138 266 294 294 322 330 569 607 618 867 1023– 1038 1141 1188 1254 1296 clinical manifestations of 1034–1035 clinical presentations of 1034 copper metabolism and pathophysiology of 1026 diagnosis of 1023 1031–1033 diagnostic tests in 1032 end stage 295 fulminant 46

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hepatic failure in 1023 presentations of 602 gene, isolation and identification of 1025 genetics of 1024–1025 1024 hepatic pathology of 1027–1029 history of 1023–1024 homozygotes 1024 light microscopic findings in liver 1028 molecular genetic studies of 1033 molecular testing 1031 neuropathology of 1029 pathologic changes of 1029–1031 pathology of 1027–1031 pathophysiology of 1025–1027 pharmacologic treatments for 1035 pharmacotherapy for 1037 recognition of 1024 structural features of 1025 symptoms of 1034 tissue damage in 294 treatment of 1035–1038 albumin dialysis 622 P.I-48 ultrastructural studies of 1033–1034 Wilson index 1460 Wilsonian fulminant hepatitis 1034 Wing-beating tremor 18 Wolman's disease 250 290 1314–1315 Woodchuck hepatitis virus (WHV) 765 World Health Organization (WHO) 749 WR See Warm reperfusion (WR) WT See Wall tension (WT)

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Copyright ©2007 Lippincott Williams & Wilkins > Back of Book > Index > X

X Xanthelasma 681 Xanthine oxidase 1473 Xanthomas 690 cutaneous 1310 Xanthomata 342 Xanthomatous cells 271 Xanthomatous change 272 Xenobiotics 219 1012 Ximelagatran 981

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Copyright ©2007 Lippincott Williams & Wilkins > Back of Book > Index > Y

Y Yeast histoplasmosis 286 Yersinia 1394 Yersinia enterocolitica 1437 YKL-40 72 Yolk sac 187 Yttrium 89 90 147 neutron bombardment of 147 particle SIRT, results of 147 radioactive microspheres, intra-arterial delivery of 147 Yttrium 99 radioactive 147

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Copyright ©2007 Lippincott Williams & Wilkins > Back of Book > Index > Z

Z Zafirlukast 981 Zellweger's syndrome 1140 1310 1317 Zidovudine 843 Zilver stent 138 Zinc 373 589 measurement in blood 373 supplementation 373 589 Zinc therapy 1037 oral 1024 Zonal necrosis 937 Zygomycosis 1566

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Schiff's Diseases of the Liver (2 Volume Set) 10th ed

Signaling Pathways in Liver Diseases 2nd ed

Allergy and Allergic Diseases, 2 Volume Set

Practical Management of Liver Diseases

Mastery of Surgery, 2 Volume Set, 5th ed

Principles and Practice of Infectious Diseases: 2-Volume Set

Schiff's Diseases of the Liver (Diseases of the Liver (Schiff)), 11th Edition

Fibrocystic Diseases of the Liver (Clinical Gastroenterology)

Fibrocystic Diseases of the Liver (Clinical Gastroenterology)

Sherlock's Diseases of the Liver and Biliary System (Sherlock Diseases of the Liver), 12th Edition

Theocritus 2 Volume Set

Hydrocolloids : 2-Volume Set

Theocritus 2 Volume Set

Magician 10th Aniversary Ed

Molecular Pathology of Liver Diseases (Molecular Pathology Library, Volume 5)

Dictionary of the Fungi 10th ed

Legends of the Jews (2-Volume Set)

Pediatric Surgery: 2-Volume Set (Grosfeld, Pediatric Surgery) 6th ed

Measure Theory (2 Volume Set)

Peripheral Neuropathy: 2-Volume Set

Measure Theory (2 Volume Set)

Infectious Diseases: Expert Consult 2 Volume Set, Third Edition volume Vol 1-2

Battleground: Immigration (2 Volume Set)

Bastiat Collection (2 Volume set)

The Competency Toolkit Volume 1 of a 2 Volume Set

Encyclopedia of Polymer Research (2 Volume Set)

Encyclopedia of Education Law (2 Volume Set)

Characterization of Materials, 2 Volume Set

Encyclopedia of Homelessness, 2 Volume Set

Encyclopedia of Geomorphology ( 2 Volume Set)

Sauer's Manual of Skin Diseases, 10th Edition

Schiff's Diseases of the Liver (2 Volume Set) 10th ed

Signaling Pathways in Liver Diseases 2nd ed

Allergy and Allergic Diseases, 2 Volume Set

Practical Management of Liver Diseases

Mastery of Surgery, 2 Volume Set, 5th ed

Principles and Practice of Infectious Diseases: 2-Volume Set

Schiff's Diseases of the Liver (Diseases of the Liver (Schiff)), 11th Edition

Fibrocystic Diseases of the Liver (Clinical Gastroenterology)

Fibrocystic Diseases of the Liver (Clinical Gastroenterology)

Sherlock's Diseases of the Liver and Biliary System (Sherlock Diseases of the Liver), 12th Edition

Theocritus 2 Volume Set

Hydrocolloids : 2-Volume Set

Theocritus 2 Volume Set

Magician 10th Aniversary Ed

Molecular Pathology of Liver Diseases (Molecular Pathology Library, Volume 5)

Dictionary of the Fungi 10th ed

Legends of the Jews (2-Volume Set)

Pediatric Surgery: 2-Volume Set (Grosfeld, Pediatric Surgery) 6th ed

Measure Theory (2 Volume Set)

Peripheral Neuropathy: 2-Volume Set

Measure Theory (2 Volume Set)

Infectious Diseases: Expert Consult 2 Volume Set, Third Edition volume Vol 1-2

Battleground: Immigration (2 Volume Set)

Bastiat Collection (2 Volume set)

The Competency Toolkit Volume 1 of a 2 Volume Set

Encyclopedia of Polymer Research (2 Volume Set)

Encyclopedia of Education Law (2 Volume Set)

Characterization of Materials, 2 Volume Set

Encyclopedia of Homelessness, 2 Volume Set

Encyclopedia of Geomorphology ( 2 Volume Set)

Sauer's Manual of Skin Diseases, 10th Edition

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