Rare pediatric insulinoma case diagnosed by endoscopic ultrasonography: insights into endogenous hyperinsulinemic...

In childhood, endogenous hyperinsulinemic hypoglycemia is most commonly associated with congenital hyperinsulinism due to genetic mutations. Pancreatic neuroendocrine tumors, which have an incidence of approximately four cases per million per year, are rare in children. Detecting small lesions is challenging, and clinical suspicion is crucial for early diagnosis. This report aims to emphasize the importance of endoscopic ultrasonography (EUS) in the clinical approach to endogenous hyperinsulinism. Additionally, a focused literature review was conducted to support the diagnostic and therapeutic aspects discussed in the case.

A 16-year-9-month-old male with no prior medical history was admitted to the emergency department with excessive sweating, speech difficulties, and an inability to wake up, occurring 8 h after a post-training meal. His blood glucose was 35 mg/dL. He had experienced similar episodes previously, resolving with food intake. An extended fasting test revealed hyperinsulinemic hypoglycemia (glucose: 45 mg/dL, insulin: 15.9 µU/mL, ketone: 0.1). Imaging studies (USG, MRI, CT) failed to detect a lesion. EUS identified a 12  ×  9 mm pancreatic body lesion, confirmed as a well-differentiated grade 2 neuroendocrine tumor via fine-needle aspiration biopsy. Laparoscopic enucleation verified the insulinoma diagnosis, with no metastasis or MEN-1 findings. Following surgery, the patient remained asymptomatic with no recurrence of hypoglycemia during a 2-year follow-up.

Insulinoma should be considered in cases of hypoglycemia triggered by fasting or exercise due to its intermittent insulin secretion. Given the small size of the pancreas and the anatomical differences in children, EUS is a highly sensitive diagnostic tool for detecting small pancreatic tumors, such as insulinoma.