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Dermatographism

These lesions developed shortly after the patient scratched her back and faded soon thereafter.

Koebner Phenomenon in Psoriasis

A linear stripe of psoriasis in a patient with a diffuse psoriasis flare after stopping methotrexate. The patient reports that this lesion formed after she was scratched on her leg by her cat.

Contact Dermatitis

A stripe of contact dermatitis caused by exposure to poison ivy. Note the linear shape left by brushing against the plant.