Pathological study on livers with noncirrhotic portal hypertension and portal venous thromboembolic occlusion: report of seven autopsy cases.

Seven adult autopsied cases with noncirrhotic portal hypertension and thromboembolic occlusion of the large extra- and intrahepatic portal veins are presented. There were two types of portal venous occlusion: old thromboembolic occlusion (group A, two cases) and fresh thromboembolic occlusion (group B, five cases). In group A the occlusion was complete and the affected veins, which were identified clearly by elastic fiber stains, were characteristically shrunk to cause a long-standing portal hypertension. Extra- and intrahepatic collaterals were prominent. In group B the extra- and, sometimes, intrahepatic larger portal veins with fresh thromboemboli revealed variable degrees of phlebosclerosis, probably resulting from organization of repeated portal venous thromboemboli. These sclerotic changes further extended into the medium-sized and smaller intrahepatic portal veins. The latter and other hepatic morphology resembled those of idiopathic portal hypertension without larger portal venous occlusion (group C). Thus, in group B the widespread involvement of the portal venous system by thromboembolic events, particularly the smaller ones, might be important not only for the development of portal hypertension but also for understanding the hepatic pathology of idiopathic portal hypertension.