Neuroendocrine tumor of the extrahepatic bile duct: A case report

•Neuroendocrine tumors of the extrahepatic bile ducts are extremely rare neoplasms.•They most commonly occur in young females and usually present with painless jaundice.•Preoperative diagnosis is difficult because the findings are similar to other biliary malignancies.•Surgical resection is considered to be the only curative treatment. Neuroendocrine tumors (NETs) of the extrahepatic bile ducts are extremely rare neoplasms arising from endocrine cells and have variable malignant potential. They most commonly occur in young females and usually present with painless jaundice. Here we present the case of an asymptomatic 57-year-old woman with NET of the common bile duct that was incidentally discovered on abdominal ultrasound during a medical examination. She was admitted to our hospital with a diagnosis of hepatic hilar tumor. Computed tomography revealed the tumor surrounding the hepatic hilum and duodenum. Magnetic resonance cholangiopancreatography revealed a filling defect of the common bile duct with morphology suggestive of external compression. Endoscopic ultrasound confirmed a submucosal tumor of the duodenal bulb measuring 30×20mm in size. The patient qualified for surgery with a preoperative diagnosis of submucosal tumor of the duodenal bulb. Intraoperative examination revealed that the tumor location involved the common bile duct and/or cystic duct with no signs of invasion to other organs or metastatic lymph nodes. Excision of the biliary ducts and tumor was followed by Roux-en-Y anastomosis. Histological results showed NET grade 1. Preoperative diagnosis of NETs is difficult because of their rarity. A definitive diagnosis is usually established intraoperatively or after histopathological evaluation. For these tumors, surgical resection is currently the only treatment modality for achieving a potentially curative effect and prolonged disease-free survival.