Vasoactive Intestinal Polypeptide Secreting Tumor - VIPoma

Vasoactive Intestinal Polypeptide Secreting Tumor - VIPoma

 

Vasoactive intestinal polypeptide secreting tumor (VIPoma) is a rare endocrine tumor associated with profuse diarrhea.

Epidemiology

  • Incidence – 1/10 million
  • Age – median age of onset is 40-50 years
  • Sex – equal gender distribution
  • Occurrence – sporadic, although some occur in association with multiple endocrine neoplasia 1 (MEN 1)

Risk Factors

  • Genetic – around 5% associated with MEN 1 syndrome

Pathophysiology

  • Epithelial endocrine tumor of endodermal origin of which 50% are malignant
  • Most tumors have been found in the body and tail of the pancreas and are unifocal
  • Hormonal secretion is vasoactive intestinal polypeptide (VIP) which is the etiology of the symptoms
    • VIP is an amino acid polypeptide that binds to intestinal epithelial cells and activates cellular adenylate cyclase and cyclic adenosine monophosphate (cAMP )
  • Other tumors that can produce VIP include ganglioneuroblastoma, bronchogenic carcinoma, pheochromocytoma, medullary thyroid carcinoma and retroperitoneal histiocytoma

Clinical Presentation

  • Verner-Morrison syndrome
    • Watery diarrhea, hypokalemia and achlorhydria (WDHA triad)
    • Dehydration and renal failure
      • May occur as a result of profuse diarrhea

Diagnosis

  • Laboratory testing
    • VIP level
      • Elevated >75 pg/mL
  • Imaging studies
    • CT/MRI
  • Histological
    • Final confirmation of tumor type – special stains may be required  

 Differential Diagnosis

  • Gastroenteritis
  • Other peptide producing tumors – most commonly Zollinger-Ellison (gastrinoma)
  • Laxative abuse
  • Carcinoid tumor
  • Pancreatic cancer
  • Villous adenoma

See Also