Recurrent insulinoma in a 10-year-old boy with Down's syndrome

An insulinoma is a rare tumour with an incidence of four cases per million per year in adults. The incidence in children is not established. There is limited literature available in children with insulinoma, and only one case is reported in association with Down's syndrome in adults. Insulinoma diagnosis is frequently missed in adults as well as in children. The Whipple triad is the most striking feature although it has limited application in young children. Hypoglycaemia with elevated insulin, C-peptide and absent ketones is highly suggestive of hyperinsulinism. We present a case of 10-year-old boy with Down's syndrome with recurrent insulinoma. He was initially misdiagnosed as having an adrenal insufficiency and developed cushingoid features and obesity secondary to hydrocortisone treatment and excessive sugar intake. The tumour was successfully localised in the head of the pancreas with an MRI and octreotide scan on first presentation. Medical treatment with diazoxide and octreotide could not achieve normal blood glucose levels. The insulinoma was laparoscopically enucleated and pathological examination confirmed a neuroendocrine tumour. Subsequently, he had complete resolution of symptoms. He had a recurrence after 2 years with frequent episodes of hypoglycaemia. The biochemical workup was suggestive of hyperinsulinism. MRI and PET scan confirmed the recurrence at the same site (head of the pancreas). He had an open laparotomy for insulinoma resection. The pathology was consistent with benign insulinoma, and subsequently, he had complete resolution of symptoms. LEARNING POINTS Insulinoma is a very rare tumour in children; it should be considered in the differential diagnosis of hypoglycaemia with absent ketones.Refractory neurological symptoms like seizure, migraine, mood changes and regression of learning abilities should suggest evaluation for hypoglycaemia.MRI with contrast and PET scan would localise the majority of pancreatic beta islet cell lesions.Medical treatment with diazoxide, octreotide and the addition of corn starch in feeds is not curative but can be supportive to maintain normoglycemia until the surgical resection.Surgical resection is the only curative treatment. The surgical procedure of choice (laparoscopic/open laparotomy) depends on local expertise, preoperative localisation, tumour size and number.Surgical treatment results in complete resolution of symptoms, but all cases should be closely followed up to monitor for recurrence. The recurrence rate is four times higher in MEN1 cases.