Idiopathic portal hypertension and its pathology.

Idiopathic portal hypertension (IPH) is a disorder of unknown etiology, clinically characterized by portal hypertension (varices and portosystemic collateral vessels), splenomegaly, and anemia (hypersplenism). A similar disorder is called noncirrhotic portal fibrosis in India, and hepatoportal sclerosis seems to be the counterpart in the United States. This disease is uncommon in developed countries. Middle-aged women are more prone to IPH in Japan. The liver has no cirrhosis or pseudonodule formation, and the principal pathologic changes are considerable portal fibrosis, devastation of intrahepatic terminal portal radicles, and parenchymal atrophy of the liver secondary to portal malperfusion. The characteristic portal hemodynamics include intrahepatic presinusoidal portal hypertension, increased splenic and portal vein blood flow, and increased intrahepatic portal resistance. The prognosis is generally good depending on the management of bleeding varices. Although the etiology is obscure, certain immunologic abnormalities seem to play an etiologic role in Japanese patients, and the incidence has markedly declined in recent years in Japan, indirectly suggesting a role of infection. The theory that IPH represents an undiagnosed intrahepatic portal vein thrombosis is refuted.