Searchable abstracts of presentations at key conferences in endocrinology
Endocrine Abstracts (2015) 37 EP1102 | DOI: 10.1530/endoabs.37.EP1102

1Internal Medicine Service – Endocrinology’s Division – CHAlgarve, Faro, Portugal; 2Internal Medicine Service – CHAlgarve, Faro, Portugal; 3Clinical Pathology Service – CHAlgarve, Faro, Portugal; 4Day Hospital Nurse – CHAlgarve, Faro, Portugal; 5Radiology Service – CHAlgarve, Faro, Portugal; 6Gastroenterology Service – CHAlgarve, Faro, Portugal; 7Hepato-pancreato-biliary Surgery Division – Hospital Curry Cabral, Faro, Portugal.


Introduction: Functional islet β-cell tumours represent 1–2% of all pancreatic neoplasms. Diagnosing this type of tumour is often challenging because they present with unspecific clinical features overlapping more common syndromes. Diagnosis involves expensive testing, so, establishing whipple’s triad and excluding causes of exogenous hyperinsulinaemia is crucial before initiating investigation.

Objective: To report a rare case of a proinsulinoma.

Case report: A 47-year-old woman was sent to the endocrinology department for evaluation of suspected spontaneous hypoglycaemia. There were no relevant antecedents. For 2 years she had had adrenergic/neuroglicopenic symptoms that relieved after ingestion of carbohydrate. She had gained 20 kg/2 years. Fractionated-diet, excluding simple carbohydrates, failed to improve symptoms. The patient was taught how to use a glucose meter to measure capillary blood glucose (BMT) and instructed to do a diary, that include meals content and BMT during symptoms. Study revealed hypoglycaemias (BMT (50 mg/dl) without a predictable pattern. Laboratorial investigation confirmed endogenous hyperinsulinism secondary to autonomous proinsulin secretion. A study with CTscan-with-contrast, ultrasound and ecoendoscopy, showed a single oval nodule with 17×13 mm. Given the nodule to be unique and with very suggestive features of proinsulinoma, it was decided not to perform aspiration cytology. The patient started treatment with diazoxide while waiting for surgery. In September of 2014, she underwent a tumour enucleation, without complications. The histopathological study confirmed a low-grade neuroendocrine tumour. In the postoperative period symptoms/hypoglycaemia resolved and there was no hyperglycaemia or diabetes mellitus.

Conclusion: The work-up of fasting hypoglycaemia is crucial because a wrong diagnosis can lead to unnecessary pancreatectomy or a missed pancreatic tumour. Localisation is challenging so imaging studies should only take place once the diagnosis has been established. Highly specific serum insulin assay can difficult the diagnosis. An enucleative approach minimises the risk of developing post-operative diabetes, leading to a favourable prognosis.

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