Urticaria pigmentosa in the armpit

Urticaria pigmentosa is characterized by few to many brownish spots which itch and, when scratched, produce welts and reddened skin. The brown spots contain cells with high levels of histamine. Individuals sometimes develop flushing and headache resulting from the massive release of histamine from these spots. This is the typical appearance of one of these spots (often referred to as a mastocytoma).

Review Date: 11/30/2022
Reviewed By: Ramin Fathi, MD, FAAD, Director, Phoenix Surgical Dermatology Group, Phoenix, AZ. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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