[Idiopathic myositis].

The idiopathic myositis, dermatomyositis, polymyositis and inclusion body myositis are recognized by their clinical and laboratory presentation, and by morphological changes in the muscle biopsy. A rapid diagnostic process is important, in order to start early treatment, which will be more effective and to direct further investigations and management. In the presence of dermatomyositis a precise investigation of neoplasia is important because they are often associated, which is not the case with inclusion body myositis. Symptoms in dermatomyositis and polymyositis respond sometimes quite well to immunomodulatory therapy but not in inclusion myositis. Controlled muscle training may sometimes slow progression in inclusion myositis.