Ectopic insulinoma diagnosed by (68)Ga-Exendin-4 PET/CT: A case report and review of literature

RATIONALE: Ectopic insulinomas are extremely rare and challenging to diagnose for clinicians. Precise preoperative localization is essential to successful treatment. PATIENT CONCERNS: A 23-year-old man presented with a 1-year history of recurrent hypoglycemia. DIAGNOSIS: Examinations in the local hospital did not reveal any pancreatic lesion. After admission, a fasting test and a 5-hour oral glucose tolerance test (OGTT) suggested a diagnosis of endogenous hyperinsulinemic hypoglycemia. Enhanced volume perfusion computed tomography (VPCT) revealed 2 nodules in the tail of the pancreas, a nodule in the gastric antrum, and a nodule in the hilum of the spleen. To differentiate which nodule was responsible for hypoglycemia, we performed (68)Ga-Exendin-4 PET/CT and (68)Ga-DOTATATE PET/CT which helped to make a conclusive diagnosis that the lesion in the gastric antrum was an ectopic insulinoma. INTERVENTIONS: The patient was cured with minimally invasive laparoscopic resection of the tumor. OUTCOMES: The symptoms were relieved and the blood glucose level remained normal after surgery. CONCLUSIONS: This case shows that (68)Gallium-exendin-4 PET/CT is useful for precise localization and thereby successful treatment of insulinoma, especially for occult insulinomas and those derived from an ectopic pancreas.