Pulmonary lymphoma developed during long-term methotrexate therapy for psoriasis.

Low dose weekly administration of methotrexate has been thought to be effective for both rheumatoid arthritis (RA) and psoriasis. However, there is a possibility that methotrexate therapy may be oncogenic. This report presents a case of pulmonary lymphoma developed during long-term methotrexate therapy for psoriasis. Physicians should be aware that Epstein-Barr virus-associated lymphoproliferative disorders that occur during treatment with methotrexate are not specific to patients with RA.