Efficacy of probenecid for a patient with juvenile dermatomyositis complicated with calcinosis.

Calcinosis of juvenile dermatomyositis (JDM) is a crucial problem because it is refractory to various therapies. An 11-year-old boy who had been treated for JDM with interstitial pneumonia developed calcinosis of both legs despite treatment with corticosteroid and cyclosporin A. Images of his knees showed massive calcinosis with restricted range of motion. Probenecid was used to reduce calcinosis, resulting in remarkable improvement of calcinosis accompanied by normalization of serum phosphorus level and disability after 17 months of administration. We suggest that probenecid is useful for the treatment of calcinosis of JDM.