Endocrine Abstracts

Introduction: Tuberous sclerosis complex (TSC) is a multisystem inherited disease associated with neurocutaneous manifestations and multiple hamartomas but rarely associated with neuroendocrine tumours (NETs). The current TSC guidelines do not recommend routine screening for NETs in TSC.

Case report: 21 year old male with genetically confirmed tuberous sclerosis (TSC-2 mutation) with intellectual disability, epilepsy with previous episodes of status epilepticus and stable subependymal giant cell astrocytoma. Medications included Sodium valproate, Clobazam, Lamotrigine, Perampanel, Cenobamate and buccal midazolam as needed. His usual seizure frequency was several absence seizures throughout the day but only 1-2 generalised tonic-clonic seizures per month. He was admitted with increased frequency of generalised tonic-clonic seizures over the preceding few weeks and was found to have spontaneous hypoglycaemia (1.9 mmol/l). Subsequent investigations confirmed endogenous hyperinsulinism (fasting laboratory blood glucose 1.9 mmol/l, C-peptide 0.56 (0.34-1.8 nmol/l) insulin 43.7 (12-150 pmol/l)). Short synacthen test, thyroid function tests and antiepileptic drug levels were satisfactory. CT of the chest, abdomen and pelvis did not reveal any concerning abnormalities; neuro-imaging showed a stable astrocytoma. A Tektrotyd scan did not reveal any Tektrotyd avid pancreatic lesion. Given high suspicion of underlying insulinoma clinically, he underwent endoscopic ultrasound which revealed an 18 mm hypoechoic lesion close to the tail of pancreas and splenic hilum. A biopsy confirmed well differentiated pancreatic NET with expression of insulin (Ki-67 <2%)

Management: His blood sugars were managed with a combination of diazoxide, subcutaneous octreotide and intravenous dextrose infusions. After the biopsy confirmed pancreatic insulinoma, he underwent laparoscopic spleen preserving distal pancreatectomy with complete excision of underlying insulinoma. After surgery, his diazoxide, octreotide and dextrose infusions were stopped and he did not have any further hypoglycaemic episodes.

Conclusion/learning points: Insulinoma is an uncommon pancreatic NET. It is rarely associated with TSC but should be considered in people with TSC who have spontaneous hypoglycacemia or increased seizure frequency, as early diagnosis and surgical management results in better treatment outcomes.