Vipoma

(also called Verner Morrison syndrome, WDHH syndrome and pancreatic cholera). This is an endocrine tumour usually from the islet cells of the pancreas that secretes excessive amounts of vasoactive intestinal polypeptide (VIP), which causes a distinct syndrome characterized by large volume profuse watery diarrhoea without steatorrhoea (more than 5 liters a day), hypokalaemia and hypochlorhydria (WDHH). Although the exact cell of origin is not known, there is a presumption that the tumour arises from the D1 cells which should be responsible for the hypersecretion of VIP.

80% of cases are caused by a pancreatic tumour, either an adenoma or a carcinoma (in equal frequency), 10% are secondary to islet cell hyperplasia and in 10% of cases the tumours responsible for the excessive secretion of VIP are located outside the pancreas. They include ganglioneuroblastoma (mostly in childhood), phaeochromocytoma or malignant bronchial tumours.

The large volume diarrhoea is secretory in nature and persist during fasting. It causes large losses of potassium in the diarrhoea fluid resulting in plasma hypokalaemia causing weakness, lethargy, nausea and vomiting. Hypochlorohydria due to the inhibitory effect of VIP on gastric acid secretion is present in two third of patients. Episodes of flushing resembling those seen in carcinoid syndrome are seen in 20% of patients and has been attributed to the vasodilatatory effects of VIP.

Barium study of the upper gastrointestinal tract may show nonspecific features such as dilution of barium in the small bowel due to the large amount of secreted fluid. The definitive diagnosis of VIPoma requires the demonstration of elevated serum concentrations of VIP. The role of diagnostic imaging is to locate the tumour anatomically. See islet cell tumour.

ALB