Cryptococcosis associated with low-dose methotrexate for arthritis.

One patient with psoriatic arthritis and a second with rheumatoid arthritis were each treated with low-dose methotrexate (10 to 15 mg per week, orally) for more than a year before pulmonary cryptococcosis developed. These are the first case reports of opportunistic fungal disease during this treatment. Low-dose methotrexate may be more immunosuppressive than has been appreciated. Patients demonstrating pneumonitis while receiving this therapy should be carefully evaluated to rule out an infectious cause.