Watery diarrhea syndrome: Two unusual cases and further evidence that VIP is a humoral mediator

Two unusual cases of the watery diarrhea syndrome are presented. In one patient an adrenal medullary tumor, a pheochromocytoma that produced vasoactive intestinal polypeptide (VIP) was excised with total relief of symptoms. The second patient, a 65-year-old man with abrupt onset of massive watery diarrhea that led to acidoses and coma, was symptomatically controlled for one year on 10 mg/day of prednisone. Elevated levels of VIP returned to normal after prednisone therapy was started. A benign islet cell tumor not localized by angiography was removed by distal pancreatic resection. Tissue levels of VIP were markedly elevated. VIP is a humoral mediator of the watery diarrhea syndrome. Both benign and malignant pancreatic and extrapancreatic tumors may cause the watery diarrhea syndrome. Steroids may cause symptomatic relief of the diarrhea by lowering peptide levels to normal. The term watery diarrhea syndrome may be more accurate than the pancreatic cholera syndrome.