Urticaria pigmentosa is the name given to a type of mastocytosis. Urticaria pigmentosa is a disease that produces skin lesions and deeply itching. It is caused by excessive numbers of inflammatory cells (mast cells) in the skin. Other forms include solitary mastocytoma (a single lesion) and systemic mastocytosis (involvement in organs other than the skin). Urticaria pigmentosa is the childhood...