Sporadic insulinoma in a 10-year-old boy: a case report and literature review

Insulinoma is an exceedingly uncommon pancreatic islet cell neuroendocrine tumor. Its estimated incidence is approximately four cases per million individuals per year. We report the case of sporadic insulinoma in an exceptionally very young 10-year-old boy who presented with a 1-month history of episodic tremulousness, diaphoresis, increased hunger, confusion and fainting. Initial laboratory investigations showed low blood glucose (64 mg/dL) and high blood insulin (6 μU/mL) levels. Patient was admitted in view of frequent hypoglycemic symptoms and possible pancreatic insulinoma. A 48-hour mentored fasting test was done and ceased within 3 hours due to occurrence of hypoglycemic symptoms. During the episode, blood was drawn and results showed low blood glucose level and high insulin, pro-insulin and C-peptide levels. The hypoglycemic symptoms were relieved greatly by glucose administration and Whipple's triad for insulinoma was met. An abdominal contrast-enhanced computed tomography scan showed a 10 x 12 x 17 mm, small, well-demarcated, heterogeneously enhancing lesion within the body of pancreas without dilatation of pancreatic duct. No evidence of lymphadenopathy or distant metastasis was identified. Patient underwent enucleation of pancreatic tumor. Histopathological and immunohistochemical examination of the pancreatic mass confirmed neuroendocrine tumor (insulinoma). Patient had an uneventful recovery. A post-operative 6-month follow-up showed resolution of hypoglycemic symptoms, normalized blood glucose, insulin, pro-insulin and C-peptide levels, and no evidence of recurrence. Although rare, sporadic insulinoma should be considered in the differential diagnosis of any young individual presenting with frequent hypoglycemic symptoms (neuroglycopenic and/or autonomic nervous system symptoms). Furthermore, a literature review on insulinoma is presented.