Mucin‐producing bile duct tumors: radiological–pathological correlation and diagnostic strategy

Mucin-producing bile duct tumors are characterized by intraductal papillary tumors producing large amounts of mucin. The tumor comprises macroscopically prominent intraductal papillary neoplastic epithelia and produces a large amount of viscid mucin, resulting in dilatation of the bile ducts. The surface of the tumor is frond-like, velvety, or serrated. The tumor exhibits five intraductal growth patterns; polypoid intraductal growth, mucosal spreading growth, cast-like intraductal growth, cystic tumor, and intraductal floating tumors. Imaging features reflect the interplay between the morphology of the tumor, the amount of mucin production, and biliary dilatation. This review article describes the radiological manifestations of the tumor, based on pathological-radiological correlation and biological behavior.