Endocrine Abstracts

Introduction: Insulinoma is a rare tumor that causes spontaneous fasting hypoglycemia in a supposedly healthy adult. Mostly these tumors are single and benign, few are malignant and a minority is represented by multiple adenomas. The treatment of choice is surgical removal of the insulinoma, which cures the condition in the majority of cases. However, after performing the surgery, less than 10% of patients either develop diabetes mellitus or continue to have persistent hypoglycemia.

Case presentation: Patient, male, 68 years old, with history of high blood pressure and ischemic stroke, presents for a month the following: diaphoresis, dizziness, altered general state, relieved by carbohydrates intake. Five days before admission in our service, he presented acute symptoms and a fingerstick blood glucose level of 25 mg/dl. During his hospital stay, he did not tolerate the fast and repeated blood samples showed low laboratory glucose and elevated plasma insulin (up to 1000 uU/ml). Further hormonal tests excluded MEN1 syndrome. The CT scan identified one small tumor located in the body of the pancreas. The patient was referred to surgery and distal subtotal pancreatectomy was performed (intraoperative ultrasound confirmed the tumor). TNM staging fits the tumor as pT1N0 and histopathological examination confirmed the neuroendocrine tumor of the pancreas, well-diferentiated (G1). After surgery the general condition of the patient was improved, but he started to present alternating episodes of mild hyperglycemia and hypoglycemia with elevated plasma insulin. The post-operative MRI scan showed no residual tumor or other pancreatic lesions. “Whole-body” somatostatin receptor scintigraphy (99mTc-Tektrotyd) with the addition of SPECT-CT was performed and it revealed a small nodule with intense uptake, in the most caudal part of the pancreas. The patient is scheduled for the second intervention.

Conclusions: The peculiarity of the case is represented by the unstable metabolic balance: the patient developed post-pancreatectomy diabetes mellitus, but in the presence of the second (previously unsuspected) insulinoma this translated into fluctuations of glycemia around normal levels (both hypo- and hyperglycemia) in the absence of treatment.