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► Urticaria pigmentosa on the chest

Urticaria pigmentosa on the chest

Urticaria 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.