VIPoma overview
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VIPoma overview On the Web |
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Madhu Sigdel M.B.B.S.[2]Parminder Dhingra, M.D. [3]
Overview
VIPoma was first described in 1958 by Verner and Morrison. A VIPoma is a rare tumor of the non-beta cells of the pancreas that results in the overproduction of the hormone vasoactive intestinal peptide (VIP). On microscopic histopathological analysis, findings of VIPoma are composition of uniform, small to intermediate-sized cells in clusters, nests, and trabecular growth patterns with hyperchromatic nuclei and scant cytoplasm. There are no established causes for VIPoma. VIPoma must be differentiated from ganglioneuroblastoma, ganglioneuroma, factitious diarrhea, bile salt enteropathy, rectal vilous adenomas, and laxative abuse. The incidence VIPoma is approximately 0.01 per 100,000 individuals worldwide. Females are more commonly affected with VIPoma than male. The incidence of VIPoma increases with age, the median age at diagnosis is 50 years. The most common risk factor in the development of VIPoma is positive family history of multiple endocrine neoplasia type 1. If left untreated, patients with VIPoma may progress to develop watery diarrhea, abdominal pain, bloating, nausea, vomiting, skin rash, backache, flushing, and lethargy. Common complications of VIPoma include metastasis, cardiac arrest from low blood potassium level, and dehydration. The presence of metastasis is associated with a particularly poor prognosis among patients with VIPoma, with a 5 year survival rate of 20% and 3 year survival rate of 40%. The hallmark of VIPoma is watery diarrhea. A positive history of abdominal pain, weight loss, numbness, and weakness is suggestive of VIPoma. Common physical examination findings of VIPoma include tachycardia, rash, facial flushing, abdominal tenderness, and abdominal distention. Laboratory tests used in the diagnosis of VIPoma include serum vasoactive intestinal polypeptide (VIP) levels, basal gastric acid output, and basic metabolic pannel for potassium, bicarbonate, magnesium, and calcium levels. On CT scan VIPoma is characterized by hypervascularity with diffuse multiple metastatic nodulation. Abdominal MRI is helpful in the diagnosis of VIPoma. On abdominal MRI, VIPoma is characterized by a mass which is hypointense on T1-weighted MRI and hyperintense on T2-weighted MRI. Abdominal ultrasound scan may be helpful in the diagnosis of VIPoma. Finding on ultrasound scan suggestive of VIPoma is hypoechoic tumor in the distal pancreas. Other imaging studies for VIPoma include somatostatin receptor scintigraphy and PET scan. Initial treatment in patient with VIPoma is prompt replacement of fluid and electrolyte losses. Steroids may be used to provide symptomatic relief. Surgery is the mainstay of treatment for VIPoma. Secondary prevention measures of VIPoma include a detailed history, physical examination, and imaging every 3 to 12 months up to one year post resection and every 6 to 12 months thereafter.
Historical Perspective
VIPoma was first described in 1958 by Verner and Morrison.
Pathophysiology
A VIPoma is a rare tumor of the non-beta cells of the pancreas that results in the overproduction of the hormone vasoactive intestinal peptide (VIP). On microscopic histopathological analysis, findings of VIPoma are composition of uniform, small to intermediate-sized cells in clusters, nests, and trabecular growth patterns with hyperchromatic nuclei and scant cytoplasm.
Causes
There are no established causes for VIPoma.
Differentiating VIPoma From Other Diseases
VIPoma must be differentiated from ganglioneuroblastoma, ganglioneuroma, factitious diarrhea, bile salt enteropathy, rectal vilous adenomas, and laxative abuse.
Epidemiology and Demographics
The incidence VIPoma is approximately 0.01 per 100,000 individuals worldwide. Females are more commonly affected with VIPoma than male. The incidence of VIPoma increases with age, the median age at diagnosis is 50 years.
Risk Factors
The most common risk factor in the development of VIPoma is positive family history of multiple endocrine neoplasia type 1.
Screening
According to the U.S. Preventive Service Task Force (USPSTF), there is insufficient evidence to recommend routine screening for VIPoma.
Natural History, Complications and Prognosis
If left untreated, patients with VIPoma may progress to develop watery diarrhea, abdominal pain, bloating, nausea, vomiting, skin rash, backache, flushing, and lethargy. Common complications of VIPoma include metastasis, cardiac arrest from low blood potassium level, and dehydration. The presence of metastasis is associated with a particularly poor prognosis among patients with VIPoma, with a 5 year survival rate of 20% and 3 year survival rate of 40%.
History and Symptoms
The hallmark of VIPoma is watery diarrhea. A positive history of abdominal pain, weight loss, numbness, and weakness is suggestive of VIPoma.
Physical Examination
Common physical examination findings of VIPoma include tachycardia, rash, facial flushing, abdominal tenderness, and abdominal distention.
Laboratory Findings
Laboratory tests used in the diagnosis of VIPoma include serum vasoactive intestinal polypeptide (VIP) levels, basal gastric acid output, potassium, bicarbonate, magnesium, and calcium levels.
CT
On CT scan VIPoma is characterized by hypervascularity with diffuse multiple metastatic nodulation.
MRI
Abdominal MRI is helpful in the diagnosis of VIPoma. On abdominal MRI, VIPoma is characterized by a mass which is hypointense on T1-weighted MRI and hyperintense on T2-weighted MRI.
Echocardiography or Ultrasound
Abdominal ultrasound scan may be helpful in the diagnosis of VIPoma. Finding on ultrasound scan suggestive of VIPoma is hypoechoic tumor in the distal pancreas.
Other Imaging Findings
Other imaging studies for VIPoma include somatostatin receptor scintigraphy and PET scan.
Medical Therapy
Initial treatment in patient with VIPoma is prompt replacement of fluid and correction of electrolyte imbalance and acid-base disturbance. Somatostatin analogues like short acting octreotide is useful for controlling diarrhea by blocking the release of VIP. Octreotide is later replaced by longer acting depot preparation of somatostatin analogues like sandostatin or lanreotide.
Surgery
Surgery is the mainstay of treatment for VIPoma. Surgery should be considered after initial symptomatic management of VIPoma in operable cases. Complete surgical resection of tumor is the only curative treatment for VIPoma. If the tumor cannot be removed completely, surgical debulking may have palliative effect for control of hormonal symptoms.
Primary Prevention
There is no established measures for the primary prevention of VIPoma.
Secondary Prevention
Secondary prevention measures of VIPoma include a detailed history, physical examination, and imaging every 3 to 12 months up to one year post resection and every 6 to 12 months thereafter.