An Unusual Presentation of Multiple Endocrine Neoplasia Type 1 (MEN1) in an adolescent - Insulinoma

Abstract Multiple endocrine neoplasia type 1 ( MEN1 ) is an autosomal dominant inherited endocrine tumor predisposition syndrome. The syndrome predisposes mutation carriers to develop several endocrine tumors with a high lifetime incidence of primary hyperparathyroidism, pituitary adenomas, and neuroendocrine tumors (NETs) of the pancreas NET and duodenum NET. These tumors are considered the cardinal manifestations of the syndrome. We report the case of a 14-year-old boy who presented with symptomatic endogenous hyperinsulinemic hypoglycemia and hypercalcemia. He was diagnosed with MEN1 , given the presence of parathyroid adenoma and pancreatic insulinoma, along with a family history of his father having prolactinoma, collagenoma, parathyroid adenoma, and gastrinoma. Although hyperparathyroidism is the most frequently encountered condition found in MEN1 , it is not always the first biological or clinical abnormality to appear in MEN1 .