Mastocytosi, most common in children

Mastocytosis is the term for a group of disorders caused by too many "mast cells". It is most common in children, but the more important forms are seen in both children and adults. Mast cell are found throughout the body, but are especially plentiful in the skin and digestive tract. Mast cells are part of the immune defense system. They are also found around wounds, and seem to play a role in healing of injuries. Mast cells work by releasing chemicals that attract white blood cells to areas of the body where they are needed. 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, which 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 the accumulation of mast cells in the tissues and can affect organs such as the liver, spleen, bone marrow, and small intestine. Urticaria pigmentosa was first described in 1869, while systemic mastocytosis was first reported in the scientific literature in 1933. The true incidence 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.)

Symptoms

Chemicals released by mast cells cause physiological changes that lead to typical allergic read more