These tumors arise from cells in the pancreas that produce vasoactive intestinal peptide.
The main symptom is watery diarrhea.
Diagnosis includes blood and imaging tests.
Treatment is replacement of fluids and electrolytes and surgery.
Vipomas are a type of pancreatic endocrine tumor Overview of Pancreatic Endocrine Tumors The pancreas is an organ located in the upper part of the abdomen. It produces digestive juices that are secreted into the digestive tract. The pancreas also produces insulin, which helps control... read more . 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 Multiple Endocrine Neoplasia Syndromes (MEN) Multiple endocrine neoplasia syndromes are rare, inherited disorders in which several endocrine glands develop noncancerous (benign) or cancerous (malignant) tumors or grow excessively without... read more .
Symptoms of Vipoma
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.
Because the diarrhea removes many of the body’s normal salts, people often develop low blood levels of potassium (hypokalemia Hypokalemia (Low Level of Potassium in the Blood) In hypokalemia, the level of potassium in blood is too low. A low potassium level has many causes but usually results from vomiting, diarrhea, adrenal gland disorders, or use of diuretics. A... read more ) and excessively acidic blood (acidosis Acidosis Acidosis is caused by an overproduction of acid that builds up in the blood or an excessive loss of bicarbonate from the blood (metabolic acidosis) or by a buildup of carbon dioxide in the blood... read more ). These changes can cause lethargy, muscular weakness, nausea, vomiting, and crampy abdominal pain. Some people have flushing.
Diagnosis of Vipoma
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.
People with elevated levels of VIP should also have the imaging tests endoscopic ultrasonography Ultrasound Scanning (Ultrasonography) of the Abdomen Ultrasound scanning uses sound waves to produce pictures of internal organs ( see also Ultrasonography). An ultrasound scan can show the size and shape of many organs, such as the liver and... read more , positron emission tomography Positron Emission Tomography (PET) Positron emission tomography (PET) is a type of radionuclide scanning. A radionuclide is a radioactive form of an element, which means it is an unstable atom that becomes more stable by releasing... read more (PET), and octreotide scintigraphy or arteriography (an x-ray taken after a radiopaque dye is injected into an artery) to detect the location of the vipoma.
Treatment of Vipoma
Replacement of fluids and electrolytes
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.