A 19-year-old man develops new lesions at the sites of skin trauma. The lesions appear as sharply marginated erythematous papules with silvery-white scales.For the above patient with a skin lesion, select the most likely diagnosis.

Koebner phenomenon is typically seen in psoriasis. The kind of injury eliciting the phenomenon is usually mechanical, but ultraviolet light or allergic damage to the skin may be provocative. Koebner phenomenon can also occur in lichen planus, lichen nitidus, keratosis follicularis, and pemphigoid. The Koebner phenomenon has been used to study early skin changes in these diseases.