Ectopic insulinoma: case report

Abstract Background Ectopic insulinoma is a rare entity that is difficult to diagnose before surgery. This article reports two cases of ectopic insulinoma. Case presentation Two patients manifested recurrent hypoglycemia with a typical Whipple triad. In terms of the qualitative diagnosis, the oral glucose tolerance test (OGTT) suggested a diagnosis of hyperinsulinemic hypoglycemia. However, preoperative imaging did not show a significant mass in the pancreas. In one patient, preoperative abdominal enhanced volume perfusion computed tomography (CT), somatostatin receptor imaging and 99mTc-HYNIC-TOC SPECT/CT revealed a mass with a rich blood supply anterior to the duodenum. In the other patient, preoperative enhanced CT, magnetic resonance imaging (MRI) and 68Ga-Exendin-4 PET/CT showed a mass above the spleen. After surgical removal of the tumor, both patients received a confirmed diagnosis of neuroendocrine tumors by postoperative pathology. The symptoms of hypoglycemia were relieved after surgery, and the blood glucose level was significantly increased. Conclusion Ectopic insulinoma is difficult to locate before surgery. 68Ga-Exendin-4 PET/CT has a high diagnostic value. Surgical removal of the lesion is main treatment.