[Proliferative lesions in thorotrast-deposited livers pertaining to the development of primary cancers]

We obtained human cadavers livers with thorotrast deposits and examined them light microscopically. The bile ducts of the large portal tract exhibited many foci of intraductal papillary hyperplasia including some severe atypical foci. The proliferation of bile ductules at the periportal zone was more marked in cases with cholangiocarcinoma than in those with other diseases. Micro-peliosis, in which the number of lining endothelial cells was significantly increased, was prominent in angiosarcoma cases. We suggest that advanced micro-peliosis represents a specific proliferative lesion pertaining to the development of angiosarcoma. There were many hyperplastic lesions of hepatocytes with structural deformity that often proceeded to vague nodular growth.