A rare cause of diarrhea: pancreatic VIPoma

Pancreatic Vasoactive Intestinal Peptide-Producing Tumor as a Rare Cause of Acute Diarrhea and Severe Hypokalemia

Pancreatic vasoactive intestinal peptide-producing tumor (VIPoma) is a rare functional neuroendocrine tumor most commonly presenting with watery diarrhea and electrolyte abnormalities that include hypokalemia, hypercalcemia and metabolic acidosis. This type of tumor has usually insidious clinical behavior that is characterized by chronic secretory diarrhea, lasting usually from months to years before diagnosis, not responsive to usual medical or dietary treatment approaches. Given the resemblance of VIPoma with other more common causes of chronic watery diarrhea, the final diagnosis is often delayed and the tumors are usually large and metastatic at the time of detection. Our case of pancreatic VIPoma demonstrates an unusual clinical course for this type of tumor with acute refractory diarrhea and rapid deterioration of patient's clinical and biochemical status that required emergent in-hospital diagnosis and treatment. Our patient is a 45-year-old woman who presented with abrupt, watery diarrhea during the past 24 h before admission accompanied with severe hypokalemia as well as hyponatremia, hyperglycemia and hypercalcemia. Despite aggressive management with fluid administration and electrolyte replenishment, no significant improvement in patient's symptoms and electrolyte imbalance was observed. After exclusion of other causes of acute diarrhea from the medical history and the laboratory tests, the clinical suspicion of a functional neuroendocrine tumor was raised. After the establishment of final diagnosis of pancreatic VIPoma with biochemical tests and magnetic resonance imaging (MRI), somatostatin analogues were prescribed and the patient underwent distal pancreatectomy and splenectomy with no signs of lymph node and splenic metastases. Few days after the surgical resection of the tumor, the patient readmitted to our hospital with tarry stools and severe anemia. The abdominal computed tomography (CT) revealed a retroperitoneal cystic lesion. The gastrointestinal bleeding gradually recessed after endoscopic hemostasis of duodenal ulcer lesions whereas the cystic lesion (postoperative lymphocele) was successfully drained under CT-guidance before discharge. After almost 10 years postoperatively, the patient is still asymptomatic with no signs of relapse or metastasis of the disease in the periodic laboratory and imaging follow-up. In conclusion, pancreatic VIPoma can sometimes manifest symptoms of abrupt onset and rapid progression that require high clinical suspicion, appropriate diagnostic workup and aggressive management.

Diagnostic and Management Challenges in Vasoactive Intestinal Peptide Secreting Tumors: A Series of 15 Patients

OBJECTIVES

Vasoactive intestinal peptide-secreting tumors (VIPomas) are rare functioning neuroendocrine tumors often characterized by a difficult-to-control secretory syndrome and high potential to develop metastases. We hereby present the characteristics of 15 cases of VIPomas and provide a recent literature review.

METHODS

This was a retrospective data analysis of 15 patients with VIPoma from 3 different centers and literature research through PubMed database during the last 10 years.

RESULTS

Fifteen patients with VIPomas (9 with hepatic metastases at diagnosis) with watery diarrhea and raised VIP levels were studied. Ten patients (67%) had grade 2 tumors, 6 of 15 had localized disease and underwent potentially curative surgery, whereas the remaining 9 received multiple systemic therapies; 3 patients died during follow-up. The median overall survival was 71 months (range, 41-154 months). Patients who were treated with curative surgery (n = 7) had longer median overall survival compared with patients who were treated with other therapeutic modalities (44 vs 33 months).

CONCLUSIONS

The management of VIPomas is challenging requiring the application of multiple treatment modalities. Patients who underwent surgical treatment with curative intent appear to have higher survival rate. Central registration and larger prospective studies are required to evaluate the effect of currently employed therapies in these patients.