It is only recently that the term "intraductal papillary mucinous neoplasm (IPMN)," which is accepted as a distinct disease entity of the pancreas, has begun to be used as "intraductal papillary neoplasm of the bile duct (IPN-B)" for mucin-secreting bile duct tumor. This evidence concerns the gene MUC5AC and pancreatic intraductal papillary-mucinous neoplasm.