Overview

A VIPoma is an uncommon neuroendocrine tumor, most often arising in the pancreas, that secretes large amounts of vasoactive intestinal peptide (VIP). The resulting hormonal excess produces a characteristic clinical picture sometimes called Verner–Morrison syndrome or WDHA (watery diarrhea, hypokalemia, achlorhydria). These tumors are rare and typically present in adults; incidence estimates describe them as occurring only a few times per 10 million people each year, underscoring their uncommon nature.

How VIPomas affect the body

VIP is a peptide hormone with multiple actions in the gastrointestinal tract and elsewhere. When produced in excess by a tumor, VIP stimulates intestinal secretion of water and electrolytes, inhibits gastric acid production, and can relax smooth muscle and blood vessels. These effects produce the dominant clinical features of profuse secretory diarrhea, low potassium levels, and reduced stomach acid. Excess VIP can also influence cardiovascular and central nervous system function.

Typical signs and symptoms

Symptoms often reflect fluid and electrolyte loss and may progress gradually or appear after a variable interval. Common clinical features include:

  • Watery, persistent diarrhea that does not improve with fasting.
  • Hypokalemia (low blood potassium), which can cause muscle weakness and cramps.
  • Achlorhydria or low gastric acid, contributing to digestive symptoms.
  • Dehydration, weight loss, and fatigue from ongoing fluid losses.
  • Less commonly, cardiac or neurological symptoms related to electrolyte disturbance and vasoactive effects of VIP.

Diagnosis and investigation

Diagnosing a VIPoma requires combining clinical suspicion with laboratory and imaging studies. Typical steps include:

  • Measurement of blood VIP levels when clinical features suggest the syndrome, together with tests documenting hypokalemia and acid suppression.
  • Stool studies to confirm a secretory pattern of diarrhea (high stool volume with low osmotic gap).
  • Cross-sectional and functional imaging of the pancreas and abdomen to localize a tumor, often followed by biopsy for histologic confirmation.
  • Assessment for metastatic disease, since many neuroendocrine tumors are discovered after spread beyond the pancreas.

For background on pancreatic origins see pancreas and for the hormone itself see vasoactive intestinal peptide (VIP). Cardiac and neurologic implications are further discussed at cardiac complications and neurological effects.

Treatment and prognosis

Initial management focuses on correcting dehydration and electrolyte imbalances, notably potassium replacement. Tumor-directed therapy depends on stage and may include surgical resection for localized disease, which can be curative. For advanced or metastatic tumors, medical therapies may reduce VIP secretion and control symptoms: somatostatin analogues, targeted agents, liver-directed procedures, and peptide receptor radionuclide therapy are among options used in specialized centers. Long-term outlook varies by tumor size, spread at diagnosis, and response to therapy; many patients benefit from symptom control even when the tumor cannot be cured.

History, epidemiology and notable points

VIPoma was first described in the mid-20th century by Verner and Morrison, and the eponym Verner–Morrison syndrome persists in medical literature. Because the syndrome produces a striking triad of diarrhea, hypokalemia and low gastric acidity, it is often taught as a classic endocrine cause of secretory diarrhea. Given its rarity, care is typically coordinated by teams with expertise in neuroendocrine tumors and gastroenterology.