Condition: Urticaria Pigmentosa

Urticaria pigmentosa is a rare skin disorder that is a localized (cutaneous) form of mastocytosis. Some clinicians suggest that urticaria pigmentosa is the childhood form of mastocytosis. Mast cells are specialized cells of connective tissue that release substances such as histamine (a chemical important in the inflammatory process) and heparin (an anti-clotting agent) when the body’s alarm mechanism is set off. When mast cells cluster and multiply excessively (proliferate), histamine and heparin are released into the skin (mastocytosis). The characteristic skin lesions of urticaria pigmentosa appear in these areas. Urticaria pigmentosa is generally benign and is usually self-limited. The exact cause of the disease is not known, although some cases may be inherited.