Endocrine Abstracts

Objective: To highlight an unusual cause of hyperinsulinaemic hypoglycemia

Methods: Case Report: Results or Case Presentation

A previously healthy and fit 52 year old gentleman of Asian descent presented with recurrent severe neuroglycopenic hyperinsulinemic hypoglycemic symptoms, suggestive of insulinoma. On several occasions he was confirmed to have severe hypoglcaemia with venous blood glucose values ranging between 1.5 and 2.7 mmol/l with inappropriate high level of insulin and C-peptide of 32 mc/unit per ml (N. 2–23) & 4.5 ng/ml (N. 0.78–5.19) respectively. Other hormonal assessment including pituitary hormones, chromogranin A, urinary 5-HIAA, and cortisol were all normal. CT imaging picked up a 4×4 cm well circumscribed lesion in the tail of the pancreas, with no lesion elsewhere. Endoscopic ultrasonography confirmed the mass to be avascular and within the pancreas. He underwent laparoscopic distal pancreatectomy uneventfully in February 2016. Histology of the tumour showed a well differentiated neuroendocrine tumour of a carcinoid variety, grade 2, with positive staining for chromogranin A, and Synaptophysin CK. Following surgery, the patient had no further hypoglycemia and remained symptom free up to 9 month of follow up. Postoperative PET scan and CT scanning of chest, abdomen and pelvis showed no recurrence of the tumour, and no lesion elsewhere.

Discussion: Non-islet cell tumours induced hypoglycemia is generally caused by big IGF-II molecules secretion. Rarely carcinoid tumours were reported to secrete insulin but this is usually in the context of carcinoid syndrome and has been reported to arise from tumours in the lungs, appendix and the liver. For a silent pancreatic carcinoid tumour to cause hyperinsulinaemic hypoglycemia is rather unusual. Plausible mechanisms include processing and secretion of insulin from tumour cells. Alternatively secretion of insulin from adjacent islet cells may have been caused by paracrine effects. The exact mechanism in our case, however, only remains speculative.

Conclusion: Tumours of the pancreas causing hypoglcemia may not necessarily be insulinoma. Silent neuroendocrine tumour of the carcinoid (Argantafinoma) variety may be the culprit.