VIPoma (Werner-Morrison syndrome): what is it, symptoms, treatment, prognosis

What is VIPoma?

VIPoma or Werner-Morrison syndrome - a rare type of tumor pancreasproducing vasoactive intestinal peptide (VIP), a substance that causes severe watery diarrhea. VIPomas arise from cells in the pancreas that produce a vasoactive peptide in the intestine. Liquid diarrhea is the main symptom.

Diagnostics include blood tests and imaging tests. Treatment includes fluid and electrolyte replacement and surgery.

Werner-Morrison syndrome is a type of pancreatic endocrine tumor. Approximately 50-75% of tumors are cancerous (malignant). In about 6% of people, VIPoma occurs during a disorder called multiple endocrine neoplasia.

Signs and symptoms

The main symptom of vipoma is prolonged acute watery diarrhea. The intestine produces 1000-3000 milliliters of feces per day, which leads to dehydration. In 50% of people, diarrhea is persistent, while in the rest, the severity of diarrhea changes over time.

Because diarrhea removes many of the normal body salts from the body, people often have low levels of potassium in their blood (hypokalemia) and excessively acidic blood (acidosis). These changes can cause lethargy, muscle weakness, nausea, vomiting, and abdominal cramping. Some people get hot flushes.

Causes

Vasoactive intestinal peptide (VIP) is a neurohormone produced in the central nervous system, as well as in the neurons of the gastrointestinal tract (GIT), respiratory and urogenital tract. It functions as a vasodilator and regulator of smooth muscle activity, stimulating the secretion of water and electrolytes from intestinal tract, inhibitor of gastric acid secretion and stimulator of blood flow, mainly in the gastrointestinal path.

Epidemiology

VIPomas are rare tumors with a frequency of 0.05% to 2.0%, which can occur in both children and adults. In adults, they most often occur between the ages of 30 and 50, and most often occur inside the pancreas (95%). A small proportion of tumors secreting vasoactive intestinal peptide (VIP) include colorectal cancer, lungs' cancer, pheochromocytoma, neurofibroma and ganglioneuroblastoma. Most VIPs arise as isolated tumors, but in about 5% of patients they are part of type 1 multiple endocrine neoplasia (MEN1) syndromes. By the time the diagnosis was made, more than 50% of VIPs had metastases.

In children, Werner-Morrison syndrome is usually diagnosed between the ages of 2 and 4 years. Most VIPomas in children are ganglioneuromas or ganglioneuroblastomas arising from the neural crest tissue of the sympathetic ganglia, in the mediastinum or retroperitoneal space. They can also arise from the medulla. adrenal glands.

Pathophysiology

Excessive secretion of VIP from a tumor has multiple effects on various organ systems, and its main effects are associated with the gastrointestinal tract system. VIP is a neurotransmitter belonging to the secretin-glucagon family and consists of 28 amino acids. It is a potent stimulator of intestinal cyclic adenosine monophosphate (cAMP) production and an inhibitor of gastric acid secretion. It promotes vasodilation, glycogenolysis, lipolysis and bone resorption. Effects secondary to these actions of VIPs include an enormous secretion of water and electrolytes by epithelial cells of the gastrointestinal tract, hypokalemia, facial redness, decreased gastric acidity, increased levels of blood glucose and hypercalcemia.

Diagnostics

The physician bases the diagnosis of Werner-Morrison syndrome on the person's symptoms of diarrhea and the finding of elevated levels of vasoactive intestinal peptide (VIP) in the blood.

People with elevated VIP levels should also undergo imaging studies of endoscopic ultrasonography, positron emission tomography (PET), and scintigraphy or arteriography with octreotide (x-ray taken after a radiopaque contrast agent is injected into an artery) to determine vipoma location.

Treatment

First, you need to make up for the lack of fluids and electrolytes (minerals in the blood such as potassium and sodium) through a vein (intravenously). Bicarbonate should be given to replace bicarbonate lost in feces and prevent acidosis. As water and electrolytes continue to be excreted in the feces after rehydration, doctors may find it difficult to continually replace water and electrolytes.

The drug octreotide usually relieves diarrhea, but large doses may be required.

Surgical removal of the vipoma cures about 50% of patients in whom the tumor has not spread. Surgery can temporarily relieve symptoms in people in whom the tumor has spread. Chemotherapy drugs can reduce diarrhea and tumor size, but they do not cure the disease.

Forecast

The average survival rate of patients with VIPoma is 96 months. It mainly depends on the degree, stage and surgical resectability of the tumor.

According to the latest recommendations from the National Comprehensive Cancer Network (NCCN), follow-up after resection includes history and physical examination, multiphase CT or MRI, and serum VIP in the first 3-12 months. After one year, it is recommended to perform the same measures every 6-12 months.