Vasoactive Intestinal Polypeptide Secreting Tumor - VIPoma

Vasoactive intestinal polypeptide secreting tumors (VIPomas) are very rare pancreatic neuroendocrine tumors (PNETs) associated with profuse diarrhea. They are usually single tumors and metastatic at diagnosis. Generally, laboratory testing includes an electrolyte panel and vasoactive intestinal peptide test.

Diagnosis

Indications for Testing

Chronic, profuse, secretory diarrhea

Criteria for Diagnosis

  • Documented elevated (>200 pg/mL) vasoactive intestinal polypeptide (VIP) concentration (National Cancer Institute [NCI], 2018) in patient with large-volume secretory diarrhea (Vinik, North American Neuroendocrine Tumor Society [NANETS], 2010)
    • VIP level >75 pg/mL highly suggestive
  • Large-volume diarrhea (Kulke, NANETS, 2010)
    • 70-80% of patients with VIPoma have more than 3L/day
    • Virtually all patients with VIPoma have >700mL/day
  • Hypokalemia
  • Achlorhydria

Laboratory Testing

  • Electrolytes
  • VIP level

Histology

  • Definitive diagnosis requires biopsy and pathologist examination
    • Useful immunohistochemical stains may include chromogranin A, synaptophysin, and cytokeratin​
    • For detailed descriptions, including recommended tests, refer to ARUP’s Immunohistochemistry Stain Offerings

Imaging Studies

  • Computed tomography (CT)/magnetic resonance imaging (MRI) or endoscopic ultrasound
  • Somatostatin-receptor scintigraphy

 Differential Diagnosis

Monitoring

Plasma chromogranin – often used to monitor functional and nonfunctional PNETs after resection (Vinik, NANETS, 2010)

Background

Epidemiology

Risk Factors

Genetic – ~5% associated with MEN1 (Jensen, 2012)

Pathophysiology

  • Most tumors occur in the body and tail of the pancreas and are unifocal (other locations include adrenal, paraganglia)
  • Symptoms result from the secretion of the peptide hormone VIP, an amino acid polypeptide that is a potent stimulator of intestinal secretion and inhibitor of gastric acid secretion
  • Other tumors can produce VIP – ganglioneuroblastoma, bronchogenic carcinoma, pheochromocytoma, and medullary thyroid carcinoma

Clinical Presentation

  • Verner-Morrison syndrome (pancreatic cholera)

ARUP Laboratory Tests

Initial testing in evaluation of diarrhea

Aid in the diagnosis of VIPoma

Aid in monitoring; not recommended for diagnosis of carcinoid tumors

May be useful in monitoring nonsecretory sympathetic and parasympathetic neuroendocrine tumors

Aid in histologic identification of neuroendocrine tissue

Stained and returned to client pathologist; consultation available if needed

Aid in histologic diagnosis of VIPoma

Stained and returned to client pathologist; consultation available if needed

Aid in grading of neuroendocrine tumors

Determine mitotic rate of tissue

Stained and resulted by ARUP

Aid in histologic identification of neural and neuroendocrine tissue

Stained and returned to client pathologist; consultation available if needed

Related Tests

Aid in the diagnosis and monitoring of PNETs

Medical Experts

Contributor

References

Additional Resources