Insulinoma initially misdiagnosed as migraine.

Abstract

Insulinoma is a rare functional neuroendocrine tumor of pancreatic islet cells that produces excessive insulin leading to neuroglycopenic and autonomic symptoms relieved by glucose. We report a case of a 39-year-old woman with recurrent neuroglycopenic symptoms for nearly five years, initially misdiagnosed as migraine, until she presented to ED with a collapse secondary to hypoglycemia. Biochemical confirmation was obtained during a supervised 72-hour fast, with symptomatic hypoglycemia which showed lowest glucose levels of 1.7mmol/L, elevated C-peptide levels of 2,271pmol/L, high insulin levels of 83.5 mU/L and a negative sulfonylurea screen. Imaging demonstrated a large hyper enhancing pancreatic mass, confirmed by ⁶⁸Ga-DOTATATE PET as a solitary lesion without metastasis. Histopathology revealed a well-differentiated Grade 1 neuroendocrine tumor measuring 90×65×40 mm. Following surgical intervention, she demonstrated a successful recovery. This case emphasizes the need to consider insulinoma early in the differential diagnosis of recurrent neuroglycopenic episodes to prevent serious complications and avoid inappropriate treatments.