MedlinePlus Medical Encyclopedia: Dermatographism on the arm

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Dermatographism on the arm

Dermatographism is a condition where lightly scratching the skin raises wheals or welts. Histamine is released at the site, causing the small blood vessels (capillaries) to dilate, producing redness and localized swelling.

Update Date: 10/23/2006

Updated by: Kevin Berman, MD, PhD, Associate, Atlanta Center for Dermatologic Disease, Atlanta, GA. Review provided by VeriMed Healthcare Network.

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