Upper common bile duct neuroendocrine tumor presenting with obstructive jaundice: a case report and literature review.

Background: The common bile duct (CBD) neuroendocrine tumor (NET) is a rare biliary tumor accounting for less than 2% of gastrointestinal neuroendocrine neoplasms (NEN). It is usually non-functional and grows submucosally, making the diagnosis of the condition during surgery difficult, and may be confused with cholangiocarcinoma. Case presentation: We report a case of a 61-year-old woman who presented with 1-month obstructive jaundice and 6-kg weight loss. Laboratory test results showed increased levels of bilirubin whereas levels of AFP, CEA, CA19-9, and CA125 showed normal results. The CT and MRI findings showed upstream dilation of the bile ducts with a hypervascular mass in the superior CBD measuring 1.7-1.8 cm. Hyperenhancement in the arterial phase and normal serum CA19-9 levels were suggestive of NET as one of the possible differentials. The patient underwent resection of the CBD, cholecystectomy, regional lymph node dissection, and Roux-en-Y hepaticojejunostomy with R0 margins confirmed via frozen section. The patient did not get any disease for the 24-month follow-up. Literature review: A systematic PubMed search using strict anatomical and pathological criteria identified 25 previously published primary CBD NET cases since 2010; combined with the index case, 26 cases were analyzed. The mean age was 47.3 ± 22.9 years, and the mean tumor diameter was 2.19 ± 0.87 cm, with a near-even male-to-female ratio (54%:46%). Jaundice (65%), abdominal pain (46%), and pruritus (35%) were the most common symptoms. Well-differentiated NET was the predominant subtype (62%), most often G2 (56% of NET cases), followed by neuroendocrine carcinoma (27%) and mixed neuroendocrine-non-neuroendocrine neoplasm (11%). CBD resection with lymphadenectomy and Roux-en-Y hepaticojejunostomy was the most common procedure (46%), followed by pancreaticoduodenectomy (31%), mainly for lower-segment lesions. No recurrence was reported in 69% of cases at last follow-up. Conclusions: CBD NET should be considered in those with obstructive jaundice, with hypervascular biliary lesions, and without raised tumor markers. Surgical treatment should include R0 resection and regional lymphadenectomy. Pathological grade, Ki-67 index, lymph node status, and resection margins are the most important factors in prognosis. An important principle is to keep watching for long periods after complete resection of low and intermediate grade tumors.