Malignant lymphoma in rheumatoid arthritis treated by low doses of methotrexate

: The authors report a case of non-Hodgkin's malignant lymphoma which developed in a patient under low-dose methotrexate for rheumatoid arthritis. Although rheumatoid arthritis without immunosuppressive therapy may be associated with an increased incidence of malignant lymphoma, the immunosuppressive effects of methotrexate may further promote the development of malignant lymphoma.