Tubulopapillary adenoma of the gallbladder accompanied by bile duct tumor thrombus

Intraductal papillary mucinous neoplasm of the bile duct(IPNB)is recognized as a precancerous lesion;however,both its pathogenesis and progression remain unclear.We present here a case of IPNB arising from the gallbladder accompanied by bile duct tumor thrombus in a 79-year-old female.The resected specimen revealed a tubulopapillary adenoma with no malignant cells.This case suggests that even in the absence of malignant cells,these tumors can behave as malignant tumors requiring aggressive treatment.Even if no malignant cells are present,intraepithelial neoplasms occurring in the ampullopancreatobiliary tract can behave as malignant tumors.