Well-differentiated endocrine tumor of the distal common bile duct: a case study and literature review.

Primary carcinoid tumors of the extrahepatic biliary tree are exceedingly rare, accounting for 0.2-2% of all digestive carcinoids. The authors in this study describe a case of biliary duct primary well-differentiated endocrine tumor in a 30-year-old man with symptoms of biliary obstruction and watery diarrhoea. Abdominal ultrasound showed a 2-cm solid lesion in the head of the pancreas, compressing the distal common bile duct. A computed tomography scan confirmed these findings, revealing the hypervascular pattern of the tumor. Gastrointestinal hormonal screening demonstrated an increase in plasma serotonin. The patient underwent standard pylorus-preserving pancreatoduodenectomy. Pathological examination showed a neuroendocrine tumor of the distal common bile duct measuring 1.8 cm in greatest dimension. The tumor cells were immunopositive for neuron-specific enolase (NSE), chromogranin A, synaptophysin, serotonin, and cytokeratin. Stains for gastrin and somatostatin were negative. Seven years later, the patient is well, with no evidence of disease. Given the site of these tumors and the difficulty in differentiating them from periampullary lesions, decisions as to the appropriate surgical approach may be problematic. After an exhaustive review of the literature, the authors conclude that pancreatoduodenectomy is the treatment of choice.