Ultrastructure of fibrolamellar oncocytic hepatoma

The fibrolamellar variant of hepatocellular carcinoma is described and the ultrastructural findings in three cases are reported. The findings confirm the oncoytic nature of the tumor and the presence of distinctive bands of collagen. This tumor may represent a neoplasm of hepatic oncocytes. It appears to have distinct epidemiologic differences from other hepatocellular carcinomas, which typically arise in cirrhotic livers, and it may have a better prognosis. As such, it should be recognized as a distinct clinicopathologic subset in the broad group of hepatocellular carcinomas.