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Dermatographia

Last reviewed dd mmm yyyy. Last edited dd mmm yyyy

Authoring team

Dermographism:

  • this is one of the physical urticarias. Seen in about 5% of the population, it is usually asymptomatic. It may however become symptomatic with features of discomfort or itching
  • the reaction represents an exaggeration of the wheal response following scratching of the skin e.g. when towelling dry after a bath. The doctor can reproduce this condition by drawing a line on the skin of the back which results in linear wheals at the site of the 'line drawing'
  • the patient who has dermographism may also have ordinary urticaria as well

White dermographism:

  • seen in individuals with atopic dermatitis - in white dermographism firm stroking of the skin with a pointed instrument does not lead to the usual response characterized by a red line, flare, and wheal reaction - instead the initial red line is replaced, generally within a period of 10 seconds, by a white line without an associated wheal

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