The triad of DM, gall stones and steatorrhoea is associated with which one ofthe following tumours.

Somatostatinoma is a tumor of the delta cells of the endocrine pancreas that produces somatostatin. Increased levels of somatostatin inhibit pancreatic hormones and gastrointestinal hormones. Thus somatostatinomas are associated with mild diabetes mellitus (due to inhibition of insulin release), steatorrhoea and gallstones (due to inhibition of cholecystokinin release), and achlorhydria (due to inhibition of gastrin release). Somatostatinomas are commonly found in head of pancreas. Only ten percent of somatostatinomas are functional tumours , and 60-70% of tumours are malignant. Nearly two thirds of patients with malignant somatostatinomas will present with metastatic disease. Ref Davidson edition23rd pg840