VIPoma is a rare form of endocrine tumor that generally originates from the non-β islet cells of the pancreas which produce the vasoactive intestinal peptide or VIP. Massive amounts of vasoactive intestinal peptide hormone may lead to increased intestinal secretions that result in profoundly chronic watery diarrhea thereby causing dehydration, achlorhydria, hypokalemia, vasodilation, acidosis, hyperglycemia and hypercalcemia. VIPoma may also be associated with another disorder called multiple endocrine neoplasia type 1.
The condition is also alternately known as the Verner Morrison syndrome, pancreatic cholera syndrome or WDHA-syndrome.
This is a very rare condition that affects approximately 1 in per 10000000 individuals in a year.
The exact factors that lead to the development of VIPoma are not known. However, a genetic link is suspected to be responsible for its causation. The families having a history of multiple endocrine neoplasia type 1 or other similar conditions are vulnerable to the disease.
The major clinical symptoms associated with VIPoma are prolonged periods of extreme watery diarrhea. The fasting stool volume may be in excess of 750 to 1000 mL in a day. Nearly 50% of the patients suffer from relatively constant diarrhea and the rest experience alternating episodes of moderate and severe diarrhea. A third of the total number of patients may have diarrhea for less than one year prior to the diagnosis but in almost 25% of the cases, symptoms of diarrhea may persist for more than 5 years prior to the diagnosis. Other signs and symptoms that are frequently noticed include:
- Muscle weakness
- Reduced appetite
- Unexplained weight loss
- Flushing or facial redness
- Impaired glucose tolerance
- Abdominal cramps and pains
Apart from the general clinical picture, the diagnostician may decide to obtain fasting VIP plasma dosage to confirm the diagnosis. Imaging tests are employed to find the location of the tumor that generally presents as metastatic during observation.
The tests generally conducted to evaluate VIPoma may include the following:
- Blood chemistry tests (these may comprise basic tests or even a more comprehensive metabolic panel)
- MRI scans of the abdomen
- CT scans of the abdomen
- Examination of stool samples
- Endoscopic ultrasound scan
- Levels of vasoactive intestinal peptide in the blood
- Radioactive scan or somatostatin receptor scintigraphy
Doctors may also recommend tests to see if a patient is having MEN-1. These will include blood work to evaluate the levels of calcium, parathyroid hormone as well as the hormone prolactin.
VIPoma Differential Diagnosis
A number of conditions show signs and symptoms similar to that of VIPoma. Hence, it is important to differentiate VIPoma from these other disorders while attempting to determine its conclusive diagnosis. The differential diagnoses of VIPoma include taking into account health conditions such as:
- Tropical Sprue
- Villous Adenoma
- Pancreatic Cancer
- Bacterial Gastroenteritis
- Intestinal Carcinoid Tumor
- Zollinger-Ellison Syndrome
- Medullary Thyroid Carcinoma
- Wermer Syndrome (MEN Type 1)
The first line of treatment is to manage the symptoms that are associated with dehydration. The patient may have low levels of potassium or other minerals which are compensated by administering intravenous fluids. The next step is to manage the rate of diarrhea. Medications like octreotide and lanreotide, which are known as somatostatin analogues, can help to control diarrhea in almost 90% of cases. Along with diarrhea, hypokalemia or other metabolic abnormalities are also treated by these medicines. Once the fluid and electrolyte balance of the patient has been restored, surgery is used to remove the tumors that have developed. In cases where there are no signs of hepatic or nodal metastasis, complete resection can ensure total cure for the tumors. For patients having preoperative or intraoperative metastasis, surgical debulking will help with postoperative management of the residual disease.
If the tumor has metastasized to other locations, the doctor may decide to try out alternate ways of dealing with them instead of opting for a major operation. These alternate methods include:
- Radiofrequency ablation
- Transarterial chemoembolisation (TACE)
Radiofrequency ablation makes the use of heat generated by the radio waves to destroy the cancer cells. A cold probe is used in cryotherapy to kill the affected cells and tissues by freezing. Chemotherapeutic drugs like Capecitabine, Temozolomide, Streptozocin, Doxorubicin and Fluorouracil are used to control VIPoma symptoms that cannot be managed with surgery. When chemotherapeutic drugs are injected directly into the areas of the liver affected by the tumors, the process is known as TACE or transarterial chemoembolisation. Another substance, such as a gel or some tiny plastic beads, might be injected as well which helps to block supply of blood to the tumor and makes sure that the chemotherapeutic drugs stay around the region of the tumor.
A new form of therapy, known as peptide receptor radioligand therapy (PRRT) is currently under development which aims at targeting radiotherapy directly into the individual tumor cells.
VIPoma patients can suffer from the following complications:
- Chronic renal failure
- Spreading or metastasizing of cancer
- Cardiac arrest, due to low levels of blood potassium
Surgeries are generally able to cure VIPoma if it has not metastasized. However, in almost 50% of all cases, the tumor is already found to spread to the neighboring areas by the time it is diagnosed. This makes treatment difficult for the medical team. In such cases, life expectancy of the patients might vary anywhere between a few days to several months, depending on how much the tumor has spread. Nearly half of all patients are cured completely with treatment. For patients having pancreatic VIPoma, VIPoma without metastasis and with metastasis, the 5-year survival rate is 68.5%, 95% and 60% respectively.
As there are no known causes for this disorder, the best way to prevent the development of VIPoma is by performing regular screening tests and maintaining a good overall health. Individuals having one or more than one risk factors or people who have been previously treated for endocrine abnormalities should go for periodic evaluations at regular intervals.
Check out the following images of the tumors that are caused by VIPoma.
Picture 1 – VIPoma
Picture 2 – VIPoma Image
VIPoma is a rare endocrine condition that leads to severe diarrhea, dehydration and development of tumors within the liver. Although its diagnosis can be difficult, the condition needs regular monitoring by the medical team. The disease is curable with proper treatment as long as the tumor formations do not metastasize significantly.