VIPoma

VIPoma
Synonyms	Verner–Morrison syndrome, Pancreatic cholera, WDHA syndrome (Watery Diarrhea, Hypokalemia, and Achlorhydria)
Pronounce
Specialty	N/A
Symptoms	Profuse watery diarrhea, dehydration, flushing, cramping, weakness
Complications	Hypokalemia, achlorhydria, metabolic acidosis, renal failure, malnutrition
Onset	Typically adults aged 30–50
Duration	Chronic unless treated
Types	Pancreatic or extrapancreatic neuroendocrine tumor
Causes	Neoplasm of VIP-secreting cells
Risks	Multiple endocrine neoplasia type 1
Diagnosis	Plasma VIP level, imaging (CT scan, MRI, somatostatin receptor scintigraphy)
Differential diagnosis	Cholera, Carcinoid syndrome, laxative abuse, Zollinger–Ellison syndrome
Prevention	None known
Treatment	Surgical resection, somatostatin analogs, supportive care
Medication	Octreotide, Lanreotide, electrolyte replacement
Prognosis	Variable; often poor in metastatic cases
Frequency	~1 per 10 million annually
Deaths	Associated with complications of metastatic disease or severe dehydration

VIPoma is a rare type of neuroendocrine tumor that secretes excessive amounts of vasoactive intestinal peptide (VIP), a hormone involved in regulating intestinal water and electrolyte secretion. The excessive VIP leads to a distinct clinical syndrome characterized by profound watery diarrhea, hypokalemia (low potassium), and achlorhydria (lack of stomach acid), collectively known as WDHA syndrome or Verner–Morrison syndrome. It is also colloquially referred to as pancreatic cholera due to the similarity of symptoms to cholera infection.

Pathophysiology

VIPomas most commonly originate from the pancreas, particularly the non-β islet cells, although rare cases have been found in extrapancreatic sites such as the bronchus, adrenal gland, or colon. Approximately 50–75% of VIPomas are malignant at the time of diagnosis, frequently with metastasis to the liver or lymph nodes.

The excessive VIP causes increased intestinal secretion of water and electrolytes, reduced gastric acid secretion, and smooth muscle relaxation, resulting in:

• Chronic watery diarrhea (often exceeding 3 liters/day)
• Electrolyte disturbances including hypokalemia, hypochlorhydria, and metabolic acidosis
• Systemic vasodilation leading to flushing and hypotension
• Possible hypercalcemia and hyperglycemia

Clinical Presentation

Patients with VIPoma typically present with:

• Severe, persistent watery diarrhea (even during fasting)
• Dehydration
• Muscle weakness, cramping
• Weight loss
• Facial flushing
• Hypotension
• Nausea or vomiting (less common)

Diagnosis

Diagnosis involves a combination of clinical suspicion and confirmatory tests:

• Laboratory tests:
• Elevated serum VIP levels (>75 pg/mL)
• Electrolyte imbalances: low potassium, low bicarbonate
• Metabolic acidosis on arterial blood gas
• Imaging:
• CT scan or MRI to localize tumor
• Somatostatin receptor scintigraphy (Octreoscan) or 68Ga-DOTATATE PET/CT to detect somatostatin receptor-positive lesions
• Endoscopic ultrasound in select cases

Treatment

Treatment strategies include:

Medical Management

• Octreotide or Lanreotide – long-acting somatostatin analogs that inhibit VIP secretion and reduce diarrhea
• IV fluid and electrolyte replacement – to manage dehydration and correct imbalances
• Antidiarrheal agents – adjunctive, but generally not effective alone

Surgical Management

• Surgical resection – curative if the tumor is localized
• Debulking surgery – may help in metastatic cases to control hormone secretion

Advanced/Metastatic Disease

• Targeted therapy – e.g., everolimus, sunitinib
• Peptide receptor radionuclide therapy (PRRT) for somatostatin receptor-positive tumors
• Hepatic artery embolization or ablation for liver metastases

Prognosis

The prognosis of VIPoma depends on tumor size, location, and metastatic spread. Localized VIPomas have a good prognosis with surgical resection, while metastatic VIPomas have a poorer outcome. However, symptom control with somatostatin analogs can significantly improve quality of life.

Epidemiology

VIPomas are extremely rare, with an estimated incidence of approximately 1 per 10 million people per year. They typically occur in adults aged 30–50, with equal incidence in males and females. They may be associated with multiple endocrine neoplasia type 1 (MEN1).

See Also

• Neuroendocrine tumor
• Somatostatin
• Multiple endocrine neoplasia
• Carcinoid syndrome
• Pancreatic cancer