Chapter 18: Liver and Gallbladder Pathology

Liver and Gallbladder Pathology provides a detailed examination of hepatobiliary pathology, exploring the diverse mechanisms of injury, repair, and metabolic dysfunction that lead to systemic disease. It establishes a foundational understanding of liver microanatomy, illustrating how the zonal organization of the lobule dictates the organ's response to toxic and ischemic insults. The text meticulously delineates the processes of hepatocyte death, distinguishing between apoptosis and necrosis, and highlights the pivotal role of hepatic stellate cells in the activation of fibrogenesis that culminates in cirrhosis. Significant attention is given to the clinical manifestations of liver failure, including life-threatening complications such as hepatic encephalopathy, coagulopathy, and the complex hemodynamics of portal hypertension which drive the formation of ascites and esophageal varices. The chapter offers an exhaustive review of infectious disorders, specifically the molecular pathogenesis and serological markers of viral hepatitis (A, B, C, D, and E), while also covering autoimmune hepatitis and the predictable versus idiosyncratic patterns of drug-induced liver injury. Modern metabolic challenges are addressed through the lens of steatotic liver disease, contrasting alcohol-associated injury with metabolic dysfunction–associated steatotic liver disease (MASLD) and its progressive form, MASH. Furthermore, the discussion includes inherited metabolic conditions like iron sequestration in hemochromatosis, copper toxicity in Wilson disease, and the proteotoxic stress of alpha-1 antitrypsin deficiency. The final sections provide clinical and morphologic insights into cholestatic diseases, circulatory disturbances like Budd-Chiari syndrome, and a spectrum of neoplastic growths ranging from benign hepatocellular adenomas to malignant hepatocellular carcinoma, cholangiocarcinoma, and common gallbladder ailments such as cholelithiasis and cholecystitis.