Polymyositis (PM) and dermatomyositis (DM) are autoimmune inflammatory diseases that primarily target muscle. Although similar, PM and DM have different pathophysiologic mechanisms. Current therapy for PM and DM does not take into account these pathophysiologic differences. Recent work has started to define outcome measures to apply to future therapeutic trials, which will allow better comparison of treatment outcomes. For patients who are unresponsive to standard therapy with high dose prednisone supplemented by methotrexate and/or azathioprine it is not clear what represents the next best choice for therapy. Although there are few controlled studies in the area, there is reason to be optimistic for use of intravenous methylprednisolone pulses, intravenous gammaglobulin, cyclosporine A, tacrolimus, mycophenolate mofetil, and rituximab for nonresponding patients. Better understanding of the underlying pathophysiology of PM and DM, as well as carefully performed multicenter clinical trials is going to be necessary to make better recommendations in the future.
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