Childhood dermatomyositis: factors predicting functional outcome and development of dystrophic calcification.

The medical records of 47 children with dermatomyositis who were seen in the pediatric rheumatology clinic at the University of Michigan between 1964 and 1982 were reviewed. Although most children with dermatomyositis have a good prognosis, the best predictor of both good functional recovery and minimal calcinosis is early treatment after the onset of symptoms, using high doses of prednisone for an adequate length of time. Of the children given such treatment, 78% had good functional outcomes, and disabling calcinosis was seen in 20% or less. Children given treatment late in the course of disease and with low doses of steroids are more likely to be functionally limited and have a greater amount of dystrophic calcium salt deposition. In our study, only 33% of patients given such treatment had a mild disease course with good functional outcome. We have identified a subgroup of children with dermatomyositis who appear to do poorly despite optimal therapeutic regimens. These patients are distinguished by a severe disease course responding minimally to corticosteroid therapy and manifested by persistent muscle weakness, elevations of muscle enzyme activity, and severe generalized cutaneous vasculitis. These children are at high risk for the development of exoskeleton-like calcification; consideration should be given to combined immunosuppressive therapy early in the course of disease.