Endocrine Abstracts

Introduction: Multiple endocrine neoplasia type 1(MEN1) is an autosomal dominant disorder resulting from pathogenic variant in tumour suppressor gene MEN1 and is characterized by parathyroid, pancreatic islet and anterior pituitary tumours. We describe an unusual case of MEN1 patient who presented with pancreatic neuroendocrine neoplasms (pNEN) prior to onset of puberty.

Case report: A Caucasian boy with a diagnosis of maternally inherited MEN 1 heterozygous missense (c.547T>C) pathogenic variant entered the surveillance programme from the age of 7. At 10y, he presented with abdominal pain and diarrhoea (later diagnosed as overflow diarrhoea). During his annual fasting (6 hr) blood tests, he was found to have hyperinsulinaemic hypoglycaemia (insulin 132 pmol/L, glucose 2.2 mmol/L). MRI showed 19 mm pancreatic lesion within the tail. Controlled fast confirmed suspicion of asymptomatic hypoglycaemia due to hyperinsulinism (HI) which was treated with bedtime 15 g corn-starch. Gallium Dotatate scan showed 2 Dotatate avid pancreatic lesions in head and body as potential sources of insulin production. Tail and body of pancreas were surgically removed, however, the 2nd smaller insulinoma in the head was not excised to preserve pancreatic function. Histopathology confirmed MEN associated pNEN with diffuse microadenomatosis. Repeat MR 1-year post operatively revealed an interval increase (from 7 mm×9 mm to 11 mm×10 mm) in size of the known partially enhancing pancreatic head lesion. Consensus was reached during Neuroendocrine Tumour (NET) multidisciplinary meeting to start long acting somatostatin analogue, Lanreotide 60 mg subcutaneously 4 weekly. Treatment was well tolerated. MR pancreas was repeated 6 months after starting treatment and lesion remained unchanged in size. In view of this positive response it was decided to continue treatment.

Discussion: Primary hyperparathyroidism is usually the first manifestation of MEN1 in childhood. Insulinomas often present later in adult life and are a rare occurrence in paediatric population. There is no published data on the use and dosage of Lanreotide in paediatric patients with pNEN and guidance for its use is extrapolated from other conditions causing hyperinsulinism. The long-term prognosis of using this treatment for pNEN presenting in childhood is so far unknown. Ongoing systematic data collection for such rare diseases is important to increase knowledge base of these conditions.