[Some aspects of idiopathic myopathies of childhood].

Juvenile idiopathic myopathies are rare chronic autoimmune diseases with proximal muscle weakness and typical skin lesions. Juvenile dermatomyositis is the most common childhood myopathy. Juvenile idiopathic myopathies differ from adult-onset forms as regards prevalence, course, clinical picture, and very rare coincidence with a malignancy. Early diagnosis and combined long-term immunosuppressive therapy may significantly improve the prognosis.