Neuroendocrine carcinoma of the extrahepatic bile duct: Case report and literature review

Neuroendocrine carcinoma (NEC) of the extrahepatic bile duct is rare, and only 22 cases have been reported. Only two of these were large-cell NEC (LCNEC); the vast majority were small-cell NEC. Here, we report a third case of LCNEC of the extrahepatic bile duct. A 76-year-old male presented to a local hospital with painless jaundice. Imaging studies revealed a tumor at the hepatic hilum. The patient underwent right hepatic lobectomy, bile duct resection, and cholecystectomy. The resection specimen showed a 5.0-cm invasive neoplasm involving the hilar bile ducts and surrounding soft tissue. Histologically, the tumor consisted of nests of medium to large cells with little intervening stroma. The tumor invaded a large portal vein branch. All four excised lymph nodes were positive for metastasis, and metastatic deposits were also present in the gallbladder wall. The tumor was diffusely positive for synaptophysin and focally positive for chromogranin A. Approximately 70%-80% of the tumor cells were positive for Ki-67, indicating strong proliferative activity. A diagnosis of LCNEC was made. A few bile ducts within and adjacent to the invasive tumor showed dysplasia of the intestinal phenotype and were focally positive for synaptophysin and chromogranin A, suggesting that the dysplastic intestinal-type epithelium played a precursor role in this case. A postoperative computer tomography scan revealed rapid enlargement of the abdominal and retroperitoneal lymph nodes. The patient died 21 d after the operation. NEC of the bile duct is an aggressive neoplasm, and its biological characteristics remain to be better defined.