A case of mixed neuroendocrine non-neuroendocrine neoplasm of the distal bile duct with biliary intraepithelial neoplasia.

A 72-year-old man with obstructive jaundice, diagnosed with distal biliary carcinoma, underwent pylorus-preserving pancreaticoduodenectomy. The patient was histopathologically and immunohistochemically diagnosed with mixed neuroendocrine non-neuroendocrine neoplasm. Pathological examination revealed that the well-differentiated adenocarcinoma components occupied the superficial portion of the bile duct and the neuroendocrine carcinoma components were located in the deeper portion of the bile duct. Pathological examination showed that a portion of the biliary intraepithelial neoplasia arose from the proximal bile duct and then extended to the gallbladder. The patient was administered tegafur/gimeracil/oteracil as adjuvant chemotherapy, and the lesion did not recur for 6 months postoperatively.