Chapter 19: Liver Pathology

Liver Pathology begins by analyzing the mechanisms of jaundice, distinguishing between unconjugated and conjugated hyperbilirubinemia caused by factors such as hemolysis, obstruction, and physiologic immaturity in newborns. The text details hereditary hyperbilirubinemias, including Gilbert and Crigler-Najjar syndromes, which result from deficiencies in UDP-glucuronosyltransferase, as well as Dubin-Johnson and Rotor syndromes, which involve defects in bilirubin excretion. Significant attention is dedicated to biliary tract diseases, contrasting primary biliary cirrhosis (PBC), an autoimmune condition characterized by antimitochondrial antibodies and granulomatous bile duct destruction, with primary sclerosing cholangitis (PSC), which is strongly associated with ulcerative colitis and presents with concentric periductal fibrosis. The discussion on cirrhosis describes the disruption of hepatic architecture by fibrous bands and regenerative nodules, leading to complications such as ascites, esophageal varices, and coagulopathy. A substantial portion of the chapter covers viral hepatitis, outlining the virology, transmission routes, and serologic profiles of Hepatitis A, B, C, D, and E, including the progression to chronic disease and hepatocellular carcinoma. It also addresses alcoholic liver disease, tracing the pathologic spectrum from reversible fatty change (steatosis) to alcoholic hepatitis featuring Mallory bodies, and finally to irreversible cirrhosis. Metabolic liver disorders are thoroughly explored, including Wilson disease (copper accumulation), hereditary hemochromatosis (iron overload linked to HFE gene mutations), alpha-1-antitrypsin deficiency (causing liver damage and panacinar emphysema), and nonalcoholic fatty liver disease (NAFLD), which correlates with obesity and insulin resistance. The chapter further examines Reye syndrome and its association with aspirin use in children, as well as hemodynamic pathologies like Budd-Chiari syndrome and chronic passive congestion (nutmeg liver). Finally, the text classifies hepatic neoplasms, ranging from benign lesions like cavernous hemangiomas and hepatocellular adenomas to malignancies such as hepatoblastoma, angiosarcoma, and hepatocellular carcinoma, emphasizing the role of tumor markers like alpha-fetoprotein.