Brief Update on Dermatologic Uses of Methotrexate.

Methotrexate (MTX), an agent originally intended for anti-neoplastic use, has been successfully employed in the treatment of a variety of dermatologic conditions. In addition to its multiple clinical indications, variable dosing and modes of administration make it a viable option for patients of all ages and most comorbidities. MTX is a folate analog that antagonizes dihydrofolate reductase, thus inhibiting thymidylate synthesis and, ultimately, the production of pyrimidine. Depending on dosage, MTX can function as an anti-inflammatory agent, immunomodulator, or antimetabolite. Patients suffering from psoriasis have benefited from MTX in addition to those with atopic dermatitis, chronic urticaria, pemphigus vulgaris, bullous pemphigoid, cutaneous lupus erythematosus, cutaneous sarcoidosis, and mycosis fungoides. Although patients with these conditions can benefit from MTX treatment, the drug can cause adverse sequelae, including hematologic, pulmonary, gastrointestinal, and hepatic side effects. Therefore, the drug should be administered under careful physician supervision.