OverviewUrticaria pigmentosa is characterized by several to many brownish spots that itch and, when scratched, produce welts and reddened skin. The brown spots, seen here on the chest, contain mast cells with high levels of histamine. People sometimes develop generalized flushing and headaches from the massive histamine release from these spots.
Update Date 11/20/2014
Updated by: Richard J. Moskowitz, MD, dermatologist in private practice, Mineola, NY. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.