A potential case of intraductal tubulopapillary neoplasms of the bile duct.

Intraductal tubulopapillary neoplasm (ITPN) has been recently reported in pancreas. We experienced an unusual intraductal growing bile duct tumor, which showed the same histopathologic and immunostaining profiles as ITPN of pancreas. A 72-year-old female patient visited hospital due to intrahepatic stone. The hilar bile duct tumor was detected and incidental lung mass was found in systemic evaluation. The histopathologic finding of the two biopsy lesions was different. The lung tumor was an adenocarcinoma, and the bile duct tumor showed poorly differentiated carcinoma with eosinophilic cytoplasm. Lung lobectomy and hemihepatectomy were performed under the impression of double primary neoplasms of the lung adenocarcinoma and oncocytic variant of the biliary papillary tumor. However the histopathologic findings and immunostaining profiles of the two resected tumors were the same. Both the lung and bile duct tumors showed a tubulopapillary pattern with high-grade nuclear atypia. Pathologic findings were the same as a recently reported ITPN of the pancreas. Eosinophilic cytoplasm of the bile duct tumor was not oncocytic cytoplasm but pyknotic change due to necrosis. Here, we report the first case of ITPN of the bile duct with lung metastasis. The tumor in this case does not fit with any categories in the current biliary tumor classification. We speculate that this may be the first case of biliary ITPN.