Vipomas are a type of pancreatic endocrine tumor. About 50 to 75% of these tumors are cancerous (malignant). In about 6% of people, vipoma occurs as part of a disorder called multiple endocrine neoplasia.
The major symptom of vipoma is prolonged massive watery diarrhea. People produce 1 to 3 quarts (1,000 to 3,000 milliliters) of stool per day, causing dehydration. In 50% of people, diarrhea is constant, and in the rest, the severity of the diarrhea varies over time.
A doctor bases the diagnosis of vipoma on the person’s diarrhea symptoms and finding elevated levels of vasoactive intestinal peptide (VIP) in the blood.
Initially fluids and electrolytes (minerals in the blood such as potassium and sodium) must be replaced by vein (intravenously). Bicarbonate must be given to replace that lost in the stool and to prevent acidosis. Because water and electrolytes continue to be lost in the stool as rehydration is achieved, doctors may find it difficult to continually replace water and electrolytes.
The drug octreotide usually controls diarrhea, but large doses may be needed.
Surgical removal of the vipoma cures about 50% of people whose tumor has not spread. Surgery may temporarily relieve symptoms in people whose tumor has spread. Chemotherapy drugs may reduce diarrhea and the size of the tumor but do not cure the disease.