Endocrine Abstracts

JOINT3356

Introduction: A functioning Neuroendocrine Tumour (NET) syndrome is defined by the presence of a clinical syndrome combined with biochemical evidence of inappropriately elevated hormonal levels, with positive hormonal expression in NET cells on immunohistochemical staining. [1, 2] Insulinomas are the most frequent type of functioning NETs – they are the most common cause of hypoglycaemia related to endogenous hyperinsulinism. [3].

Objectives and Methods: This paper presents, from a clinical and therapeutic point of view, a case series of 3 insulinoma patients, treated in a tertiary centre.

Results: We analysed data from 3 patients, 1 woman and 2 men (median age at diagnosis - 51.6 years old) which were referred due to clinical suspicion of insulinoma – Whipple’s triad with no history of diabetes mellitus or glucose-lowering treatment. We performed the fasting test for the female – hypoglycaemia (<45 mg/dl) with inadequate normal insulin and C peptide levels. The other 2 patients came with spontaneous glycemia of 30-40 mg/dl with a long history of frequent crises (1 every 3-4 hours) – therefore, the clinical and biochemical diagnoses were positive. The CT exam revealed a pancreatic lesion in the tail of the pancreas in all 3 patients and also adrenal adenomas with a high lipid content – probably incidentalomas. The youngest patient, aged 40, was also diagnosed with a renal tumour of 7 cm and a pituitary microadenoma. The woman has a first-degree cousin with acromegaly, but no other positive familial or personal history suggestive of MEN1 syndrome for all 3 patients – the hormonal screening for MEN1 or other functional NETs also came back negative. The 2 older patients were referred to a general surgery clinic – one had a partial pancreatectomy (the pathology report was positive for insulinoma), with no residual disease post-surgery, but he developed secondary diabetes mellitus and is currently treated with insulin. The woman recently underwent partial pancreatectomy with no complications and complete remission, while the youngest patient was referred for a nephrectomy first, an octreotide scan to confirm the localisation and is currently treated with Diazoxid until the pancreatectomy can be performed. All 3 will be followed-up yearly and genetic testing and counselling are in progress.

Conclusions: Insulinomas are rare functioning NETs, with life-threatening symptoms, isolated or part of a syndromic disease, requiring multidisciplinary teams and expert tumour boards for correct diagnosis and management, the surgical curative excision being the only treatment to ensure a successful outcome and improve quality of life.