Histopathology of a benign bile duct lesion in the liver: Morphologic mimicker or precursor of intrahepatic cholangiocarcinoma

A bile duct lesion originating from intrahepatic bile ducts is generally regarded as an incidental pathologic finding in liver specimens. However, a recent study on the molecular classification of intrahepatic cholangiocarcinoma has focused on the heterogeneity of this carcinoma and has suggested that the cells of different origins present in the biliary tree may have a major role in the mechanism of oncogenesis. In this review, benign intrahepatic bile duct lesions—regarded in the past as reactive changes or remnant developmental anomalies and now noted to have potential for developing precursor lesions of intrahepatic cholangiocarcinoma—are discussed by focusing on the histopathologic features and its implications in clinical practice.