Mastocytosis is a disorder of mast cell proliferation that has both cutaneo
us and systemic features. The most frequent site of organ involvement in in
dividuals with any form of mastocytosis is the skin. Cutaneous lesions incl
ude urticaria pigmentosa, mastocytoma, diffuse and erythrodermic cutaneous
mastocytosis, and telangiectasia macularis eruptiva perstans.