Enucleation of pancreatic proinsulinoma: case report

Ana Pires Goncalves; Rui Almeida; Hercilia Martins; Madalena Lourenco; Jorge Pereira; Bruno Peixe; Ana Rita Clara; Conceicao Viegas; Ana Marta Nobre; Silvia Silva; Jorge Paulino Pereira; Mario Lazaro

doi:10.1530/endoabs.37.EP1102

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Endocrine Abstracts (2015) 37 EP1102 | DOI: 10.1530/endoabs.37.EP1102

ECE2015 Eposter Presentations Endocrine tumours (69 abstracts)

Enucleation of pancreatic proinsulinoma: case report

Ana Pires Gonçalves ¹ , Rui Almeida ² , Hercilia Martins ³ , Madalena Lourenço ⁴ , Jorge Pereira ⁵ , Bruno Peixe ⁶ , Ana Rita Clara ² , Conceição Viegas ² , Ana Marta Nobre ⁷ , Sílvia Silva ⁷ , Jorge Paulino Pereira ⁷ & Mário Lazaro ²

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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.