Intrahepatic peribiliary vascular plexus in various hepatobiliary diseases: a histological survey

The peribiliary vascular plexus (PVP) plays an important role in the pathophysiology of the biliary tree. We histologically examined vascular endothelial cells of the intrahepatic PVP in various hepatobiliary diseases by immunohistochemistry and lectin histochemistry with antibodies to factor VIII-related antigens (F-VIII-R-Ag) and Ulex europaeus agglutinin I (UEA-I). The PVP around the intrahepatic large bile ducts (LBDs) and septal bile ducts (SBDs) in normal livers consists of three layers: inner layer vessels immediately adjacent to the epithelium, intermediate layer vessels within the ductal wall, and outer layer vessels outside the ductal wall. In some bile ducts that show active inflammation in hepatolithiasis, primary biliary cirrhosis (PBC), primary sclerosing cholangitis (PSC), and extrahepatic biliary obstruction (EBO), vessels in the intermediate layer and, to a lesser degree, in the inner layer, are increased in number. In sclerotic bile ducts of PSC, EBO, and hepatolithiasis, the number of inner and intermediate layer vessels are markedly and variably reduced, respectively. In liver cirrhosis or chronic advanced liver diseases, the vessels in all three layers, particularly those in the outer layer, are increased in number and dilated, probably reflecting intrahepatic microcirculatory disturbance. The PVP showed several types of numerical and luminal changes, each of which may be related to disease processes in the intrahepatic biliary tree as well as to intrahepatic microcirculatory disturbance.