Multiple endocrine neoplasia type 1 (MEN 1) is a rare autosomal dominant disease characterized by pancreatic, parathyroid, and anterior pituitary tumours. Hypercalcaemia due to parathyroid tumours is usually the first manifestation. Pancreatic islet tumours occur less frequently, among them gastrinomas and insulinomas are the most prevalent. Insulinomas can be difficult to diagnose. It was not uncommon for patients to have been misdiagnosed with psychiatric illnesses or seizure disorders before insulinoma was recognized. We presented a patient who was diagnosed to have temporal epilepsy, which later turned out to be an insulinoma in MEN-1. A 23-yr-old male presented with an auditory hallucination of a voice asking him to kill his mother. He has had seizure for a year, and was being treated as temporal lobe epilepsy (TLE) with two antiepileptics. Asymptomatic hypoglycaemia was noted during his follow up for TLE; but did not trigger further investigation. He has been having recurrent hypoglycaemia during admission and remains asymptomatic even though his blood glucose went down as low as 1.8 mmol/l. Fasting C-peptide level taken during hypoglycaemia was inappropriately normal i.e. 947 pmol/l (2981324 pmol/l). MRI pancreas revealed a mass at the head and uncinate of pancreas; measuring 2.86×3.2×2.9 cm. H e was also diagnosed to have hypercalcaemia secondary to primary hyperparathyroidism. Neck US showed the presence of a probable right inferior parathyroid adenoma. He has bilateral renal calculi; with left proximal ureteric calculus causing moderate hydronephrosis and hydroureter requiring stenting. A final diagnosis of MEN-1 with Insulinoma and primary hyperparathyroidism was made. He underwent Whipples procedure instead of enucleation of the insulinoma as the tumor is adjacent to the pancreatic duct and major vessels. A total parathyroidectomy and implantatation of the left parathyroid was also performed, together with prophylactic thymectomy. He remains euglycaemic following the surgery. Insulinoma can pose a diagnostic challenge even to an experience clinician. Misdiagnosis of insulinoma as psychiatric illness and seizure is common; and might lead to disastrous consequences. This is unfortunate as insulinoma is curable after surgery. This case highlights the importance of considering insulinoma in patients presenting with seizures or psychosis.
20 May 2017 - 23 May 2017