Rheumatoid nodulosis during methotrexate therapy in a patient with rheumatoid arthritis.

We report a 62-year-old man with rheumatoid arthritis (RA) who developed nodulosis after methotrexate (MTX) treatment. The epithelioid cells of nodules were positive for matrix metalloproteinases (MMP)-2, MMP-3, MMP-9, and Ki67. The synovial tissues obtained from the same patient were negative for MMP-3, MMP-9, and Ki67. This study demonstrated that MTX-induced nodules are different from synovial tissues in terms of MMP expression, suggesting the presence of different pathologic mechanisms and differential MTX susceptibility.