A case of pediatric insulinoma misdiagnosed as atypical epilepsy for 4 years

Hypoglycemia can cause various neurological symptoms, including seizures and impaired consciousness; however, they are often non-specific and can easily be overlooked. In pediatric patients, recurrent hypoglycemia-related seizures are rare, and can frequently lead to a misdiagnosis of epilepsy. An 8-year-old boy initially presented with clonic convulsions or myoclonic jerks, primarily affecting the right upper limb without impairment of awareness. He later developed generalized tonic-clonic convulsions or non-convulsive seizures with altered consciousness and urinary incontinence. He was diagnosed with symptomatic focal epilepsy, and levetiracetam and valproic acid were initiated. At the age of 13 years, blood test results revealed hyperinsulinemia and severe hypoglycemia. Abdominal CT and a selective arterial secretagogue injection test identified a functional pancreatic neuroendocrine tumor. Subsequent surgical procedures and histopathological analyses confirmed the diagnosis of an insulinoma. These findings clarified the cause of the patient's recurrent seizures, which were secondary to severe hypoglycemia. Genetic analysis identified a pathogenic variant of MEN1 gene (NM_001370259.2(MEN1): c.784-9G>A), leading to the diagnosis of insulinoma associated with multiple endocrine neoplasia type 1. This patient underscores the diagnostic challenge of hypoglycemia-related neurological symptoms and highlights the importance of screening for hypoglycemia in pediatric patients presenting with atypical seizure features.