Clinical course is variable, but general patterns include monocyclic with recovery in about 2 years, chronic polycyclic, and chronic continuous. Relapse is uncommon after a complete remission, however a few patients have been reported to develop scleroderma later in life. Calcinosis occurs months into the course, most often with the chronic forms of the disease. It is a factor in residual disability, as is development of muscle contracture. Deaths in juvenile dermatomyositis patients can be caused by acute myocarditis, severe myositis, bowel perforation from vasculitic ulcers, occasional lung involvement, and infection.
Treatment is controversial.
For mild disease, some authors recommend qod oral prednisone alone or in combination with other agents. IVIG has proven very effective in several small studies, particularly in patients who develop steroid resistance or severe toxicity. The mechanism for its effect is unknown, but may include neutralization of viruses, suppression of autoantibody production and of cell mediated autoimmunity by masking epitopes, Fc receptors, etc. Finally, cytotoxic agents such as azathioprine, methotrexate, and cyclophosphamide are occasionally used in refractory cases. How often and how long to treat must be individualized, and is particularly difficult in acute relapses in a chronic patient.