Juvenile dermatomyositis.

Juvenile dermatomyositis (JDM) is a rare, often chronic autoimmune disease with onset during childhood. It is characterized by weakness in proximal muscles and pathognomonic skin rashes. Although the etiology remains unclear, it has been proposed that JDM is caused by a vasculopathy within the muscle tissue and multiple other organ systems of genetically susceptible individuals, possibly in response to environmental triggers. The goals of treatment include control of the underlying inflammatory myositis and prevention and/or treatment of complications (eg, contractures and calcinosis). Delayed treatment may lead to poorer outcome in terms of disease course and calcinosis. The course in JDM is variable. Monocyclic disease occurs in about one third of patients. These patients have a good response to standard therapy. Early recognition and aggressive immunosuppressive treatment result in improved prognosis.