Idiopathic inflammatory myopathies.

Dermatomyositis, polymyositis, and inclusion body myositis are the major categories of idiopathic inflammatory myopathy. These inflammatory myopathies are distinct clinically, histologically, and pathogenically. Features of dermatomyositis and polymyositis can overlap with those of other autoimmune connective tissue diseases. In this article, the authors review the characteristic features of these myopathies, update the recent developments in this area, and provide a framework for treatment.