Brain metastases from adenoendocrine carcinoma of the common bile duct: a case report.

A 68-year-old man with metastatic brain tumors from adenoendocrine carcinoma of the common bile duct is reported. A common bile duct tumor and a metastatic liver tumor had been resected 6 years and 3 years prior to admission, respectively. Microscopically they showed two components; moderately differentiated tubular adenocarcinoma and neuroendocrine carcinoma. He presented with headache and vomiting and MRI revealed two metastatic brain tumors. They were successfully resected and radiotherapy was carried out. Histological diagnosis of the metastatic brain tumors was neuroendocrine carcinoma, but carbohydrate antigen (CA)-19-9 and carcinoembryonic antigen (CEA)-immunoreactive cells were observed without glandular pattern. Immunohistochemically serotonin and pancreatic polypeptide were detected, but somatostatin was not. As the endocrine cells demonstrated in the normal extrahepatic bile ducts are only somatostatin-containing D cells, these cells are considered to originate as part of a metaplastic process. To our knowledge, this represents the second case of adenoendocrine carcinoma of the common bile duct.