Gastrinoma of Cystic Duct: A Rare Association With Multiple Endocrine Neoplasia Type 1

Neuroendocrine tumors (NETs) of cystic duct are extremely rare, accounting for less than 2% of NET cases. The association of biliary tree NET and multiple endocrine neoplasm type 1 (MEN1) are even more rare. In this report, we described a case of a 65-year-old woman who was referred to our neuroendocrine outpatient clinic to investigate MEN1 after an incidental diagnosis of gastrinoma. Her medical history initiated 7 years earlier with severe peptic disease not responsive to proton pump inhibitor therapy. Endoscopic study revealed erosive antral gastritis, erosive duodenitis, bulbar ulcer and pyloric deformity. During follow-up she presented with abdominal pain, chronic diarrhea and weight loss; an ultrasonography was performed and showed only a cholelithiasis. She underwent a video laparoscopic cholecystectomy and all her symptoms were solved. Histopathological study found a 1.0 cm well differentiated NET (Ki-67 labeling index < 2%) located in cystic duct infiltrating the entire wall and subserosa. The MEN1 investigation revealed a primary hyperparathyroidism with a brown tumor in right iliac bone; the patient was referred to a total parathyroidectomy with autotransplantation. No evidence of pituitary tumor was found. The patient remains asymptomatic 24 months after surgery. To conclude, this case highlights an unusual presentation of a cystic duct primary NET gastrinoma in a MEN1 context.