MON-911 Debilitating Neuropsychiatry Symptoms in Pancreatic Insulinoma Co-Secreting Serotonin and IGF-1

Abstract

Background: Insulinoma is the most common type of functioning pancreatic neuroendocrine tumor (NET). Polyhormonal secretions from the NET, giving rise to distinct clinical symptoms such as carcinoid symptoms are rare. Clinical Case: We report a 68-year-old woman who presented with four months history of recurrent diaphoresis, palpitations, tremors and chest tightness. These were associated with episodic paroxysms of flushing and diarrhoea. The physical examination was unremarkable. She was a well-nourished woman with BMI of 28 kg/m2. Initial laboratory tests ruled out any renal, liver abnormalities with normal cortisol and thyroid function test. Further evaluation confirms insulin mediated hypoglycaemia with low random blood sugar 2.5 mmol/l (4.4-7.8) and failure to suppress C-peptide, 1092 pmol/L (298-2350) and insulin levels, 12.7 mU/L (3-25). Urine 5-HIAA was markedly elevated 2430.37 µmol/day (3.66-42.89) with borderline elevation of serum chromogranin A level 122 ng/mL (27-94). IGF-1 was also raised at 416 ug/L (91-282). Two months later she presented with new onset of delirium, incoherence, agitation and restlessness independent of her hypoglycaemic events. These symptoms deteriorated and fluctuates throughout the day with period of normalcy in between. This has led to requirement of a full time caregiver for her. Cranial CT excluded any brain pathology. We are faced with a diagnostic challenge to localize the primary lesion as radiological imaging so far were normal. GALLIUM-68 PET CT showed physiological uptake in the uncinate process of the pancreas (SUVmax 14.4). Endoscopic ultrasound of the pancreas was normal. An intra-arterial calcium stimulation test with hepatic venous sampling (ASVS) confirms a lesion at the head of pancreas with two times increment of insulin from baseline at the gastroduodenal artery distribution. Despite elimination of hypoglycaemic events with Diazoxide 100mg twice daily, her neuropsychiatric symptoms persisted. We postulate that this might be from excessive peripheral production of serotonin by the pancreatic carcinoid tumour or a niacin deficiency state because of metabolic diversion of its precursor, tryptophan. Conclusion: This case highlights the occurrence of debilitating neuropsychiatry manifestations in a likely neuroendocrine tumour arising from the head of pancreas secreting insulin, serotonin and IGF-1.