What Is The Diagnosis?
Answer: Dermographism
The exact cause of dermographic urticaria is unknown. Histamine is the main chemical released by mast cells when the skin is stroked, but other chemical mediators may also be involved.
Some patients with severe dermographism may carry an autoantibody to some unknown cutaneous protein.
Occasionally dermographism is triggered by an allergy to some external agent such as penicillin, scabies or a worm infestation. Most people with dermographism do not have an allergy.
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