Pancreatic somatostatinoma presenting with hypoglycaemia.

A 33-year-old woman with a 2 month history of vague ill health was admitted to hospital in hypoglycaemic coma. Preoperative investigation suggested malignant insulinoma as the probable cause of illness, but immunohistological examination of the tumour showed it to consist mainly of somatostatin-containing cells but sparse insulin-secreting cells were also present. Plasma immunoreactive somatostatin levels were from fifty to 200 times the upper limit of normal and rose in response to arginine and fell during diazoxide infusion. The hypoglycaemia was unusually sensitive to the hyperglycaemic effects of diazoxide and chlorothiazide and, with 5-fluorouracil as the only specific anti-tumour agent, there has been clinical, biochemical and radiological evidence of tumour regression.