A case of rheumatoid arthritis exhibiting accelerating rheumatoid pleurisy during low-dose weekly methotrexate therapy.

A 75-year-old Japanese man suffering from rheumatoid arthritis (RA) had received methotrexate (MTX) treatment for 9 years and developed bilateral pleural thickening with exudative pleural effusions despite remission of the polyarthritis. A diagnosis of rheumatoid pleurisy, made by exclusion, was supported by the elevated rheumatoid factor level of the pleural fluid. The pleurisy developed concomitantly with MTX-induced leukocytopenia, and discontinuation of the MTX treatment partially improved the CRP level. These findings indicate a causal relation between the rheumatoid pleurisy and MTX and suggest that MTX therapy may be ineffective in the treatment of rheumatoid pleurisy. Treatment with 10 mg of prednisolone and 100 mg of cyclosporine A daily resulted in rapid resolution of the pleurisy. Although MTX-induced rheumatoid pleurisy is a rare condition, MTX therapy should be considered carefully in RA patients with concomitant rheumatoid pleurisy.