Pathology of portal hypertension

Abstract

Abstract Portal hypertension may be the result of intra‐ and extrahepatic impediment of portal venous blood flow. Portal vein thrombosis is the major cause of prehepatic portal hypertension, and hepatic vein occlusion, congestive heart failure and constrictive pericarditis lead to posthepatic portal hypertension. Cirrhosis is the most common intrahepatic lesion responsible for portal hypertension. Idiopathic non‐cirrhotic portal hypertension results from obliterative injuries more specifically directed to intrahepatic portal vascular structures (macro‐ and microvascular portal vein disease). Under these conditions, portal vascular dilatation, herniation into the periportal parenchyma and paraportal shunt vessels resemble collateral pathways. The liver parenchyma often shows nodular transformation which may even be the only clue to the presence of small portal vein obstruction in a small liver biopsy. Thus, the morphologic changes associated with idiopathic portal hypertension may be subtle and non‐specific. Their recognition, particularly in the liver biopsy, is a challenge to the pathologist.