[Inflammatory myopathies].

Primary myositis (or inflammatory myopathies) comprises three main groups of diseases, based on clinical and immunohistochemical characteristics: polymyositis (PM), dermatomyositis (DM) and inclusion body myositis. Their clinical presentation and course are disparate, but a common characteristic is immune dysfunction-related inflammation of the striated muscles. Their etiologies are still not fully elucidated but associate environmental and, to a lesser degree, genetic factors. Nevertheless, considerable progress has recently been made in the understanding and management of these diseases.