Ultrastructural analysis of the liver with portal vein agenesis: a case report.

Congenital absence of portal vein (CAPV) is a rare vascular malformation: all 16 cases up to now reported are associated with other congenital anomalies and with benign or malignant hepatic neoplasms. Our report concerns a girl with a complex malformative syndrome consisting of CAPV, nodular tumor-like hyperplasia of the liver, and multicystic kidney dysplasia. CAPV was diagnosed by angiography, showing the splenic vein and superior mesenteric vein joined to form a "common trunk" directly entering the inferior vena cava above the liver. The liver maintained the normal lobular architecture, but immunohistochemical and ultrastructural observations revealed abnormalities of the hepatocyte membranes and diffuse capillarization of the sinusoids. In this paper, we present the relationship between the tissue modification and the lobular microcirculation changes due to CAPV, with exclusive perfusion of arterial blood flow.