Methotrexate-induced epidermal necrosis.

A patient with erythrodermic psoriasis is described who developed epidermal necrosis due to methotrexate. Concurrent salicylate administration and borderline renal failure interfered with methotrexate elimination, leading to an elevated plasma methotrexate concentration 36 h after the methotrexate administration. Although the epidermal necrosis is sometimes thought to be idiosyncratic, the present case suggests that it may be a dose-related problem.