Portal vein or hepatic vein? A curious aberrant vasculature in the liver with idiopathic portal hypertension.

The existence of aberrant vasculatures has been described as one of the characteristic findings in the liver with idiopathic portal hypertension (IPH). In this paper, the morphological features and the genesis of aberrant vasculatures were studied on the basis of autopsy and biopsy materials of IPH and animal experiments. Aberrant vasculatures in IPH livers are characterized as thin-walled vessels located mainly adjacent to the portal tracts and at times in the hepatic lobules. Although some of them are morphologically very similar to hepatic vein branches, they are portal in nature. These aberrant vessels develop in order to compensate for portal circulatory insufficiency due to obliteration of portal vein branches, and play an important role in maintaining an adequate blood supply to the parenchyma. It is predicted that decrease of these intrahepatic collateral vessels is responsible for or related to parenchymal atrophy and deterioration of liver function in the advanced stage of this disease. We regard these vasculatures as characteristic of the intrahepatic portal venous obstruction, particularly with portal hypertension accompanied by increased portal blood flow.