Overview
Mastocytosis is a disorder that may occur in both children and adults. It is caused by the presence of too many mast cells in your body. You can find mast cells in skin, lymph nodes, internal organs (such as the liver and spleen) and the linings of the lung, stomach, and intestine. Mast cells play an important role in helping your immune system defend these tissues from disease. Mast cells attract other key players of the immune defense system to areas of your body where they are needed by releasing chemical “alarms” such as histamine and cytokines.
Mast cells seem to have other roles as well. Found to gather around wounds, they may play a part in wound healing. For example, the typical itching you feel around a healing scab may be caused by histamine released by mast cells. Researchers also think mast cells may have a role in the growth of blood vessels. No one with too few or no mast cells has ever been found. This fact indicates to some scientists that having too few mast cells may be incompatible with life.
The presence of too many mast cells, or mastocytosis, can occur in two forms—cutaneous and systemic. The most common cutaneous (skin) form is also called urticaria pigmentosa, which occurs when mast cells infiltrate the skin. Systemic mastocytosis is caused by mast cells accumulating in the tissues and can affect organs such as the liver, spleen, bone marrow, and small intestine.
Researchers first described urticaria pigmentosa in 1869. Systemic mastocytosis was first reported in the scientific literature in 1949. The true number of cases of either type of mastocytosis remains unknown, but mastocytosis generally is considered to be an “orphan disease.” (Orphan diseases affect approximately 200,000 or fewer people in the United States.)
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