Mastocytosis

Definition

Mastocytosis is a disease characterized by the presence of too many mast cells in various organs and tissues.

Description

The body has a variety of free-roaming cell populations that function as immunogenic agents. Most immunogenic cells fall into the category of white blood cells, but some remain in tissues and are not found in the blood. Mast cells are such a group.

Mast cells are found primarily in the skin and digestive system, including the liver and spleen, and produce histamine, a chemical most famous for its ability to cause itching. Histamine also causes acid indigestion, diarrhea, flushing, heart pounding, headaches, and can even cause the blood pressure to drop suddenly.

Mastocytosis comes in three forms. Most cases produce symptoms but do not shorten life expectancy. The three forms are:

• Mastocytoma, a benign skin tumor.
• Urticaria pigmentosa, small collections of mast cells in the skin that manifest as salmon or brown-colored patches.
• Systemic mastocytosis, the collection of mast cells in the skin, lymph nodes, liver, spleen, gastrointestinal tract, and bones.

Causes and symptoms

The cause of mastocytosis is unknown. People with systemic mastocytosis have bone and joint pain. Peptic ulcers are frequent because of the increased stomach acid stimulated by histamine. Many patients with systemic mastocytosis also develop urticaria pigmentosa. These skin lesions itch when stroked and may become fluid-filled.

Diagnosis

A biopsy of the skin patches aids diagnosis. An elevated level of histamine in the urine or blood is also indicative of mastocytosis.

Treatment

Mastocytoma usually occurs in childhood and clears-up on its own. Urticaria pigmentosa (present alone without systemic disease) also dramatically clears or improves as adolescence approaches.

Several medications are helpful in relieving symptoms of systemic mastocytosis. Antihistamines and drugs that reduce stomach acid are frequently needed. Headaches respond to migraine treatment. A medicine called cromolyn helps with the bowel symptoms. Several other standard and experimental medications have been used.

Prognosis

Mastocytoma and urticaria pigmentosa rarely if ever, develop into systemic mastocytosis, and both spontaneously improve over time. Systemic mastocytosis is only symptomatically treated. There is no known treatment that decreases the number of mast cells within tissue.

Resources

BOOKS

Austen, K. Frank. "Diseases of Immediate Type Hypersensitivity." In Harrison's Principles of Internal Medicine, edited by Anthony S. Fauci, et al. New York: McGraw-Hill, 1997.

KEY TERMS

Non-steroidal anti-inflammatory drugs (NSAIDs)— Aspirin, ibuprofen, naproxen, and many others.

Peptic ulcer— Ulcers in the stomach and upper duodenum (first portion of the small intestine) caused by stomach acid and a bacterium called Helicobacter pylori.