Bile duct adenomas in heterozygous (MZ) deficiency of alpha 1-protease inhibitor.

A case of bile duct adenomas in association with heterozygous (MZ) deficiency of alpha 1-proteinase inhibitor (API) is presented. The salient features were the presence of large API-containing globules in the adenomatous tissue and only minimally, in granular form, in hepatocytes. alpha 1-Proteinase inhibitor was not demonstrated in portal bile ducts entrapped in the adenomatous tissue or in bile ducts present in the liver parenchyma. Bile duct markers such as cytokeratin and carcinoembryonic antigens were present in the adenomatous tissue and also in the normal bile ducts, but not in the hepatocytes, suggesting that the adenomatous structures are ductular in origin, and probably not from ductular metaplasia of liver cells. Accumulation of API is postulated to be a triggering factor in neoplastic transformation.