D-penicillamine-induced myositis in rheumatoid arthritis.

D-penicillamine, an agent still used in the treatment of rheumatoid arthritis (RA) may produce inflammatory myopathy or myositis. Some reported cases are documented with muscle biopsy. We report a 34-year old female, receiving the drug for more than 4 years, who consulted us with recently developed proximal muscle pain and weakness. EMG-findings were typical for inflammatory muscle disease; muscle enzymes remained normal. D-penicillamine was stopped and she was started on prednisolone with rapid improvement. The EMG-findings, with follow-up within three months, proved to be a good diagnostic tool, in the absence of laboratory muscle enzymes abnormalities.