Information on the following diseases can be found in the Related Disorders section of this report:

• Zollinger-Ellison Syndrome
• Hypoglycemia

Symptoms of pancreatic islet-cell tumor vary with the type of hormone- producing tumor that occurs. Generally, symptoms include periodic attacks of pain in the abdomen which increase in severity and frequency. Insulin- secreting tumors may result in abnormally low blood sugar (hypoglycemia), and may produce such symptoms as headache, visual disturbances, confusion, weakness, sweating, uncontrollable tremors or quivering, loss of muscular coordination (ataxia), personality changes, palpitations, convulsions or coma. Symptoms of severe hypoglycemia may be confused with those of many neurologic or psychiatric disorders.

Pancreatic islet-cell tumors which produce the hormone gastrin commonly result in multiple ulcers. Approximately 50% of these tumors are benign and their growth and spread are slow. Symptoms of ulcers may include gastrointestinal bleeding, stomach pain and diarrhea.

Zollinger-Ellison Syndrome is characterized by multiple ulcers which may be caused by gastrin secreting islet-cell tumors of the pancreas. These ulcers commonly bleed, cause stomach pain and diarrhea. (For more information on this disorder, choose "Zollinger-Ellison" as your search term in the Rare Disease Database).

Certain pancreatic islet-cell tumors which secret the hormone vasoactive intestinal polypeptide (VIP) are responsible for such symptoms as severe watery diarrhea, dehydration, intermittent vomiting, weight loss, weakness, decreased potassium in the blood (hypokalemia), excess calcium in the blood (hypercalcemia), reduced or absent gastric secretion and degenerative changes in the spine. This disorder is called Verner-Morrison Syndrome or Pancreatic Cholera.

The exact cause of pancreatic islet-cell tumors is not known. However scientists believe certain forms of this disorder may be inherited.

Human traits, including the classic genetic diseases, are the product of the interaction of two genes, one received from the father and one from the mother. Verner-Morrison syndrome and a particular form of Zollinger-Ellison syndrome are inherited as autosomal dominant traits.

In dominant disorders, a single copy of the disease gene (received from either the mother or father) will be expressed "dominating" the other normal gene and resulting in the appearance of the disease. The risk of transmitting the disorder from affected parent to offspring is 50 percent for each pregnancy regardless of the sex of the resulting child.

Pancreatic islet-cell tumors occur most often in males between the ages of 30 and 60.

Symptoms of the following disorder can be similar to those of Pancreatic Islet-Cell Tumors. Comparisons may be useful for a differential diagnosis:

Hypoglycemia is characterized by abnormally low blood sugar, and may be caused by excess insulin in the body. Symptoms of hypoglycemia may include faintness, weakness, jitteriness, profuse perspiration, excessive hunger and nervousness. Islet-cell tumors of the pancreas may be one source of the excess insulin, although hypoglycemia often occurs for unknown reasons. (For more information on this disorder, choose "Hypoglycemia" as your search term in the Rare Disease Database.)

Small benign tumors at or near the surface of the pancreas can usually be surgically removed. If the tumor is large or deep into the body or tail of the pancreas, a portion of the pancreas may be removed. Total removal of the pancreas (pancreatectomy) is reserved only for large malignant tumors of the pancreas. Surgical cure rates are very high for small benign tumors. The drugs Diazoxide and Streptozocin (for insulinoma) are frequently administered to control symptoms or reduce the size of the tumor.

Gastrin secreting pancreatic islet-cell tumors (Zollinger-Ellison Syndrome) may be treated with the drug Cimetidine which greatly reduces gastric acid output and promotes healing and alleviates symptoms. Surgical removal of the tumor is possible in approximately 20% of all patients. Streptozocin is also used to reduce diarrhea and tumor mass. The drug Sandostatin has been found to be effective in controlling diarrhea and suppressing secretion of the hormones gastrin, insulin, glucagon and VIP by islet-cell tumors.

Pancreatic cholera (Verner-Morrison Syndrome) must be treated by replacing fluids and electrolytes lost in numerous watery stools. The tumor may be surgically removed in approximately 50% of the cases. Streptozocin may also be administered to reduce diarrhea and tumor mass. Some individuals may respond to a corticosteroid drug such as Prednisone. Sandostatin may be administered for severe diarrhea and to reduce elevated VIP levels produced by islet-cell tumors.

TEXTBOOKS
Raghavan D., ed. Textbook of Uncommon Cancer, 2nd ed. New York, NY: John Wiley & Sons, Ltd; 1999:411-12.

Berkow R., ed. The Merck Manual-Home Edition. Whitehouse Station, NJ: Merck Research Laboratories; 1997:725-26.

Beers MH, Berkow R., eds. The Merck Manual, 17th ed. Whitehouse Station, NJ: Merck Research Laboratories; 1999:332-33.

REVIEW ARTICLES
Menack MJ, et al. Laparoscopic sonography of the biliary tree and pancreas. Surg Clin North Am. 2000;80:1151-70.

Dolan JP, et al. Occult insulinoma. Br J Surg. 2000;87:385-87.

Lamberts SW. Endocrine tumors. Cancer Chemother Biol Response Modif. 1999;18:388-93.

JOURNAL ARTICLES
Anderson MA, et al. Endoscopic ultrasound is highly accurate and directs management in patients with neuroendocrine tumors of the pancreas. Am J Gastroenterol. 2000;95:2271-77.

Berends FJ, et al. Laparoscopic detection and resection of insulinomas. Surgery. 2000;128:386-91.

Lam KY, et al. Telomerase activity in pancreatic endocrine tumours: a potential marker for malignancy. Mol Pathol. 2000;53:133-36.

Ichikawa T, et al. Islet cell tumor of the pancreas: biphasic CT versus MR imaging in tumor detection. Radiology. 2000;216:163-71.