Specialty Oncology ICD-O M8155/3 MedlinePlus 000228 | ICD-10 C25.4 or E16.8 DiseasesDB 13877 | |
eMedicine med/2379 med/2399 ped/2428 | ||
A VIPoma (also known as Verner–Morrison syndrome, after the physicians who first described it) is a rare (1 per 10,000,000 per year) endocrine tumor, usually (about 90%) originating from non-β islet cell of the pancreas, that produce vasoactive intestinal peptide (VIP). It may be associated with multiple endocrine neoplasia type 1.
Contents
The massive amounts of VIP in turn cause profound and chronic watery diarrhea and resultant dehydration, hypokalemia, achlorhydria (hence WDHA-syndrome, or pancreatic cholera syndrome), acidosis, vasodilation (flushing and hypotension), hypercalcemia and hyperglycemia.
Symptoms and signs
The major clinical features are prolonged watery diarrhea (fasting stool volume > 750 to 1000 mL/day) and symptoms of hypokalemia and dehydration. Half of the patients have relatively constant diarrhea while the rest have alternating periods of severe and moderate diarrhea. One third have diarrhea < 1yr before diagnosis, but in 25%, diarrhea is present for 5 yr or more before diagnosis. Lethargy, muscle weakness, nausea, vomiting and crampy abdominal pain are frequent symptoms. Hypokalemia and impaired glucose tolerance occur in < 50% of patients. Achlorhydria is also a feature. During attacks of diarrhea, flushing similar to the carcinoid syndrome occur rarely.
Diagnosis
Besides the clinical picture, fasting VIP plasma level may confirm the diagnosis, and CT scan and somatostatin receptor scintigraphy are used to localise the tumor, which is usually metastatic at presentation.
Tests include:
Treatment
The first goal of treatment is to correct dehydration. Fluids are often given through a vein (intravenous fluids) to replace fluids lost in diarrhea.
The next goal is to slow the diarrhea. Some medications can help control diarrhea. Octreotide, which is a human-made form of the natural hormone somatostatin, blocks the action of VIP.
The best chance for a cure is surgery to remove the tumor. If the tumor has not spread to other organs, surgery can often cure the condition.
For metastatic disease, peptide receptor radionuclide therapy (PRRT) can be highly effective. This treatment involves attaching a radionuclide (Lutetium-177 or Yttrium-90) to a somatostatin analogue (octreotate or octreotide). This is a novel way to deliver high doses of beta radiation to kill tumours.
Some people seem to respond to a combination chemo called capecitabine and temozolomide but there is no report that it totally cured people from vipoma.
Prognosis
Surgery can usually cure VIPomas. However, in one-third to one-half of patients, the tumor has spread by the time of diagnosis and cannot be cured.