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.