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  • • A non-beta islet cell tumor of the pancreas that secretes VIP

    • VIPomas cause the WDHH syndrome (watery diarrhea, hypokalemia, hypochlorhydria)

    • Chronic profuse watery diarrhea

    • Massive fecal loss of potassium

    • Low serum potassium

    • Extreme weakness

    • Elevated serum vasoactive intestinal polypeptide (VIP) level

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Epidemiology

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  • • Approximately 80% of the tumors are solitary, located in the body or tail of the pancreas

    • About 50% of the lesions are malignant, and 75% of those have metastasized by the time of exploration.

    • Mean age of presentation is 47 years; women are affected 3 times as often as men

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Symptoms and Signs

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  • • Profuse watery diarrhea

    • Extreme weakness

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Laboratory Findings

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  • • Elevated fasting VIP levels (> 190 pg/mL)

    • Low serum potassium

    • Severe metabolic acidosis results from loss of HCO3 in the stool

    • Elevated serum calcium, possibly from secretion by the tumor of a parathyroid hormone-like substance

    • Mild hyperglycemia

    • Hypochlorhydria

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Imaging Findings

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  • • CT scan or MRI is the best initial imaging test for localization and metastases

    • Somatostatin receptor scintigraphy is also useful for localization

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  • • Severe chronic watery diarrhea along with metabolic acidosis and hypokalemia may prompt investigation for VIPoma

    • Severe secretory diarrhea, elevated serum VIP level and pancreatic mass suggests diagnosis

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Rule Out

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  • • Patients who complain of severe diarrhea must be evaluated carefully for other causes before seriously considering the diagnosis of VIPoma

    • Gastrinoma

    • Carcinoid

    • Medullary thyroid tumor

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  • • Documentation of severe, watery diarrhea (stool volume averages about 5 L/d during acute episodes)

    • Serum VIP level

    • CT scan or MRI

    • Somatostatin receptor scintigraphy if not detected by CT scan or MRI

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When to Admit

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  • • Severe metabolic acidosis

    • Severe hypokalemia

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  • • Octreotide for palliation of symptoms.

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Surgery

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  • • Resection of entire tumor

    • -Pancreaticoduodenectomy for tumor in head of pancreas

      -Distal pancreatectomy for tumor in body and tail

    • Palliative debulking of metastases

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Indications

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  • • All cases in which resection is technically feasible

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Medications

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  • • Long-acting somatostatin analogs decrease VIP levels, controls diarrhea, and may even reduce tumor size

    • Streptozocin if not completely resected

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Prognosis

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  • • 1-year survival is 40% in patients whose tumors cannot be completely resected

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References

Jensen RT. Overview of chronic diarrhea caused by functional neuroendocrine neoplasms. Semin Gastrointest Dis. 1999;10:156.  [PubMed: 10548409]
Soga J, Yakuwa Y. Vipoma/diarrheogenic syndrome: a statistical evaluation of 241 reported cases. J Exp Clin Cancer Res. 1998;17:389.  [PubMed: 10089056]
Jensen RT: Carcinoid and pancreatic endocrine tumors: recent advances in ...

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