Endocrine Abstracts

Background: Insulinoma is a rare neuroendocrine tumor that causes inappropriate secretion of insulin resulting in hypoglycemia. The diagnosis of insulinoma may be difficult. Recurrence after surgery is rare and it usually concerns tumors with high histological grade.

Case presentation: We report a case of a 52-year-old woman with recurrent episodes of symptomatic hypoglycemia. The laboratory investigations showed high insulin (20 IU/ml) and C-peptide levels (5.02 ng/ml) concomitant with low blood sugar levels (38 mg/dl) and absence of plasma sulfonylurea. Preoperative pancreatic imaging was negative. Exploratory surgery was performed and the peroperative ultrasound showed a pancreatic tumor of 1 centimeter. Enucleation of the tumor was performed and histopathology confirmed the diagnosis of a grade 1 insulinoma (Ki 67 <1%). Ten years later, she started experiencing symptomatic episodes of hypoglycemia with inappropriately elevated insulin (16 IU/ml) and C-peptide levels (3.03 ng/ml). Pancreatic MRI showed an 11×16 mm tumor. Splenectomy was performed and histology confirmed the diagnosis of insulinoma. Workup for multiple endocrine neoplasia turned out to be negative.

Conclusion: Insulinoma is a rare tumor that may be life-threatening by causing severe hypoglycemia. Although recurrence of sporadic insulinoma is rare, a clinical follow-up is necessary after surgery.