Rare Case of Neuroendocrine Tumor of Common Bile Duct Identified With Somatostatin Receptor But Not With Glucose Transporter Imaging

Neuroendocrine tumors (NETs) are heterogeneous group of tumors arising from enterochromaffin cells. Neuroendocrine tumors are most commonly found in bowel and pancreatic tissue. Because of paucity of enterochromaffin cells in biliary tract, NETs of bile duct are very rare. Most of the neoplasms in the extrahepatic bile duct are adenocarcinomas; only 0.2% to 0.3% of NETs arise from the bile duct. Cases reported in the literature of biliary carcinoid are diagnosed postoperatively on histopathologic evaluation. We hereby demonstrate a rare presentation of CBD NET identified preoperatively on somatostatin receptor but not on glucose transporter imaging, confirmed by histopathology and immunohistochemistry to be grade 2 NET (Ki-67, 20%).