Vasoactive intestinal peptide-secreting tumors, or VIPomas, are neuroendocrine tumors that secrete excessive amounts of vasoactive intestinal peptide (VIP), resulting in a distinct syndrome of large-volume secretory diarrhea and subsequent electrolyte disturbances.

Patients present with diarrhea that is high-volume (>1 L/day), watery, and tea-colored in appearance. Abdominal pain is notably absent or minimal. The diarrhea is severe enough to cause hypokalemia (80%-100%), hypochlorhydria (55%-75%), and dehydration. Symptoms related to fluid and electrolyte losses, including lethargy, muscle cramps / weakness, nausea and vomiting, are often present. Flushing, hypercalcemia, hyperglycemia, and hypotension can also occur secondary to VIP hypersecretion.

In adults, VIPomas are typically pancreatic in origin (80%-90%), arising from noninsulin-secreting pancreatic islet cells. Other VIP-secreting tumors, including pheochromocytomas, intestinal carcinoids, and adrenal tumors, have also been described. Most VIPomas are solitary and located in the pancreatic tail; 60%-80% of patients will have metastases at the time of presentation, most commonly in the liver. A subset of patients with VIPomas (about 5%) can have co-occurring tumors of the parathyroid and pituitary, or other tumors of the pancreas, as part of the multiple endocrine neoplasia type 1 (MEN1) syndrome. VIPomas can also be seen in children; in these cases, tumors typically occur in the sympathetic ganglia or adrenal glands.

VIPomas are rare, occurring at a rate of 1 per 10 million per year. Average age of presentation is during the fifth decade of life, and there may be a slight female predominance. Children are typically diagnosed between the ages of 2 and 4.