Developments in the classification and treatment of the juvenile idiopathic inflammatory myopathies.

This review updates recent trends in the classification of the juvenile idiopathic inflammatory myopathies (JIIM) and the emerging standard of treatment of the most common form of JIIM, juvenile dermatomyositis. The JIIM are rare, heterogeneous autoimmune diseases that share chronic muscle inflammation and weakness. A growing spectrum of clinicopathologic groups and serologic phenotypes defined by the presence of myositis autoantibodies are now recognized, each with differing demographics, clinical manifestations, laboratory findings, and prognoses. Although daily oral corticosteroids remain the backbone of treatment, disease-modifying anti-rheumatic drugs are almost always used adjunctively and biologic therapies may benefit patients with recalcitrant disease.