Case of resected small-cell neuroendocrine carcinoma of the extrahepatic bile duct.

Neuroendocrine carcinomas (NECs) arising from the extrahepatic bile duct (EHBD) are extremely rare, and their preoperative diagnosis is difficult. A small number of resected cases of EHBD NECs has been reported, and their prognosis is usually poor. A 62-year-old man presented with obstructive jaundice and liver disease. Radiological imaging revealed wall thickness and stricture of the distal common bile duct (CBD); however, lymph node or distant metastasis was not detected. Adenocarcinoma was detected on biopsy, and surgery was performed with a preoperative diagnosis of cholangiocarcinoma of the distal CBD. Pathological examination revealed adenocarcinoma of the CBD mucosa (20%) and NEC of the CBD wall (80%). The final pathological diagnosis was small-cell NEC of the EHBD. His post-operative course was good, and there was no recurrence for 4 months after surgery. Herein, we report a case of resected EHBD NEC and a literature review.