Urticaria Pigmentosa/Maculopapular Cutaneous Mastocytosis

**Semantic type:** Neoplastic Process

**Definition:** The most frequent form of cutaneous mastocytosis. In children, the lesions tend to be papular, and are characterized by aggregates of elongated or spindle-shaped mast cells which fill the papillary dermis and extend into the reticular dermis. In adults, the lesions tend to have fewer mast cells compared to those in children. The lesions are located most commonly on the trunk, but they can be seen on the extremities, head and neck. (WHO, 2001)

**Synonyms:** - UP/MPCM - Urticaria Pigmentosa - Urticaria pigmentosa