Other Tumors of the Pancreas
Insulinoma
An insulinoma is a rare type of pancreatic tumor that secretes insulin, a hormone that lowers the levels of sugar (glucose) in the blood.
Only 10% of insulinomas are cancerous.
Symptoms
Symptoms result from low levels of sugar in the blood, which occur when the person does not eat for several hours (most often in the morning after an all-night fast). The symptoms include faintness, weakness, trembling, awareness of the heartbeat (palpitations), sweating, nervousness, and profound hunger. Other symptoms include headache, confusion, vision abnormalities, unsteadiness, and marked changes in personality. The low levels of sugar in the blood may even lead to a loss of consciousness, seizures, and coma.
Diagnosis and Treatment
Diagnosing an insulinoma can be difficult. The person fasts for at least 24 hours, sometimes up to 72 hours, and is closely monitored, often in the hospital. During that time, the symptoms usually appear, and blood tests are performed to measure the levels of sugar and insulin. Very low levels of sugar and high levels of insulin in the blood indicate the presence of an insulinoma. The location must then be pinpointed. Imaging tests--such as computed tomography (CT), ultrasound scans, and arteriography (an x-ray taken after a radiopaque dye is injected into an artery) of the intestinal arteries--can be used to locate the tumor, but sometimes exploratory surgery is needed.
The primary treatment for an insulinoma is surgical removal, which has a cure rate of about 90%. When the insulinoma cannot be completely removed and symptoms continue, several drugs (for example, streptozocin and octreotide) can be helpful.
Gastrinoma
A gastrinoma is a tumor usually in the pancreas or duodenum (the first segment of the small intestine) that produces excessive levels of the hormone gastrin, which stimulates the stomach to secrete acid and enzymes, causing peptic ulcers.
Most people with gastrinomas have several tumors clustered in or near the pancreas. About half of the tumors are cancerous. Sometimes a gastrinoma occurs as part of multiple endocrine neoplasia, a hereditary disorder in which tumors arise from the cells of various endocrine glands, such as the insulin-producing cells of the pancreas.
Symptoms and Diagnosis
The excess gastrin secreted by the gastrinoma causes Zollinger-Ellison syndrome (see Section 9, Chapter 121), in which a person suffers the symptoms of aggressive peptic ulcers in the stomach, duodenum, and elsewhere in the intestine. However, as many as 25% of people with Zollinger-Ellison syndrome may not have an ulcer when the diagnosis is made. Rupture, bleeding, and obstruction of the intestine can occur and are life threatening. For more than half of the people with a gastrinoma, symptoms are no worse than those experienced by people with ordinary peptic ulcer disease. In 25 to 40% of people, diarrhea is the first symptom.
A doctor suspects a gastrinoma when a person has frequent peptic ulcers or several peptic ulcers that do not respond to the usual ulcer treatments. Blood tests to detect abnormally high levels of gastrin are the most reliable diagnostic tests. Also, samples of gastric juice--obtained by inserting a slender tube through the nose and into the stomach--show very high levels of acid. Doctors use several imaging techniques, such as computed tomography (CT), ultrasound scans, and arteriography, to locate tumors. These tumors may be difficult to find, however, because usually they are small.
Treatment
High doses of proton pump inhibitors (see Section 9, Chapter 121 and Section 9, Chapter 121) may be effective for reducing acid levels and relieving symptoms temporarily. About 20% of people who do not have multiple endocrine neoplasia can be cured with surgical removal of the gastrinoma. If these treatments fail, an operation to remove the stomach completely (total gastrectomy) may be necessary. This operation does not remove the tumor, but the gastrin can no longer create ulcers after the acid-producing stomach is removed. If the stomach is removed, daily oral iron and calcium supplements and monthly injections of vitamin B12 are needed, because absorption of these nutrients is impaired when stomach juices that prepare these nutrients for absorption are no longer available.
If cancerous tumors have spread to other parts of the body, chemotherapy may help reduce the number of tumor cells and the levels of gastrin in the blood. However, such therapy does not cure the cancer, which is ultimately fatal.
Glucagonoma
A glucagonoma is a tumor of the pancreas that produces the hormone glucagon, which raises the level of sugar (glucose) in the blood and produces a distinctive rash.
About 80% of glucagonomas are cancerous. However, they grow slowly, and many people survive for 15 years or more after the diagnosis. The average age at which symptoms begin is 50. About 80% of people with glucagonomas are women.
Symptoms and Diagnosis
High levels of glucagon in the blood cause the symptoms of diabetes mellitus. Often, the person loses weight. In 90% of people, the most distinctive features are a chronic reddish brown skin rash (necrolytic migratory erythema) and a smooth, shiny, bright red-orange tongue. The mouth also may have cracks at the corners. The rash, which causes scaling, starts in the groin and moves to the buttocks, forearms, and legs.
The diagnosis is made by identifying high levels of glucagon in the blood and then locating the tumor by arteriography (see Section 10, Chapter 134) and abdominal surgery.
Treatment
Ideally, the tumor is surgically removed, which eliminates all symptoms. However, if removal is not possible or if the tumor has spread, chemotherapy may reduce the levels of glucagon and lessen the symptoms. However, chemotherapy does not improve survival. The drug octreotide also reduces glucagon levels, may clear up the rash, and may restore appetite, facilitating weight gain. But octreotide may elevate the levels of sugar in the blood even more. Zinc ointment may be used to treat the skin rash. Sometimes the rash is treated with intravenous amino acids or fatty acids.
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