Note the linear parallel excoriations on the thigh of this boy with a history of atopic dermatitis. These lesions occurred on an erythematous base. The parallel lesions are about a finger thickness apart. We cannot determine whether the erythema is primary and caused the itching, or whether the erythema is secondary, the result of the scratching. We can conclude only that this patient itches rather badly. No primary lesions are present in this image to focus a diagnostic effort. Excoriations may penetrate through the basement membrane zone and heal with scarring.