immune disorders
Mastocytosis
Introduction
Mastocytosis is an uncommon abnormal accumulation of mast cells in the skin and sometimes in various other parts of the body. People may have itchy spots and bumps, flushing, digestive upset, and sometimes bone pain or anaphylactic and anaphylactoid reactions. Symptoms suggest the diagnosis, and a biopsy of the skin and/or bone marrow can confirm it. If mastocytosis affects only the skin, it may resolve without treatment, but if it affects other parts of the body, it cannot be cured. Antihistamines help relieve itching, and histamine-2 (H2) blockers help relieve digestive upset. People with mastocytosis should always carry self-injecting syringe ofepinephrinefor prompt emergency treatment of anaphylactic or anaphylactoid reactions. (See also Overview of Allergic Reactions .) Mastocytosis develops when mast cells increase in number and accumulate in tissues over a period of years. Mast cells are part of the Overview of the Immune System and are normally present in many body tissues, particularly the skin, lungs, and lining of the intestine. Mast cells produce histamine, a substance involved in inflammatory and allergic reactions and in the production of stomach acid. Because the number of mast cells increases, levels of histamine increase. Histamine can cause many symptoms, including digestive problems. Mastocytosis is rare. It differs from typical allergic reactions because it is chronic rather than episodic. Some people have a genetic mutation that causes mastocytosis. What causes the disorder in others is sometimes unclear. 