Incidence
- Rare
- Arises from D2 pancreatic islet cells
- Clinical Syndrome – WDHA
- Watery
- Diarrhoea
- Hypokalaemia
- Achlorhydria (absent HCl in gastric secretions)
- 2/3 malignant
-
70% have metastatic disease at presentation
- 90% found in Pancreas
- 10% in Colon, Bronchus, Liver, Adrenal, Sympathetic Ganglia
- Most middle age
- 10% diagnosed before 10yrs old (but generally VIPomas from neuroblastomas etc rather than PNETS)
- Generally solitary, > 3cm, easily seen on CT/MRI
- 75% in body and tail of pancreas
- 95% Sporadic, 5% MEN1
Presentation and Diagnosis
- Watery secretory diarrhoea
- Can be 3-5L per day, Unlikely VIPoma if < 700mLs
- Persists despite fasting, and despite NG aspiration (c.f. ZES)
- Weight loss, crampy abdo pain, electrolyte abnormalities
- Metabolic acidosis (fluid and bicarb loss)
- Hypokalaemia can be profound
- 75% have hypochlorhydria/achlorhydria
- Absence HCL in gastric secretions (VIP inhibits gastric secretion)
- Diagnosis - VIP levels 225-2000pg/mL
- Measured after overnight fast
- Normal levels < 200
Treatment
- Initial
- Aggressive rehydration and correction of electrolytes and acid-base disturbance
- Octreotide to decrease diarrhoea volumes
- If diarrhoea persists, steroid can help
- Surgery
- Anatomic resection with lymphadenectomy rather than enucleation
- No evidence to support debulking in metastatic disease
- After resection
- 5yr survival 68%
- Metastases = Poor prognostic factor