[Acquired inflammatory myopathies: interest of specific autoantibodies for their classification].

The former classification of myositis based on the clinical phenotype and muscle histology is now changing. We started from the concept of "dermatopolymyositis" to the recognition of inclusion body myositis and more recently of immune mediated necrotizing myopathies. Furthermore, during the last 10 years, the routine access to myositis associated or specific auto-antibodies permitted to fine tune homogenous subgroups of myositis patients with common phenotype, immunopathology and prognosis. Using this approach, the polymyositis group has completely disappeared, the former patients now being reclassified as having and inclusion body myositis or an overlap syndrome such as the anti-synthetase syndrome. The different subgroups of myositis associated with their specific auto-antibodies are described here.