Inflammatory Muscle Disorders - State of the Art of Diagnosis and Treatment of Myositis

Idiopathic inflammatory myopathies include polymyositis (PM), dermatomyositis (DM), necrotizing myopathy (NM), inclusion body myositis (IBM), and myositis in overlap syndromes. This is a heterogeneous group of acquired muscle diseases characterised by progressive muscle weakness and muscular atrophy. It is crucial to differentiate between the individual subtypes, especially with a view to prognosis and choice of treatment. Although the identification of muscle-specific antibodies has significantly advanced the diagnostic process in the past few years, muscle biopsy remains an indispensable element in the differentialdiagnostic workup of myositis syndromes. Due to the lack of highquality studies, most treatment recommendations continue to be based on empirical data and expert opinions, and the first interdisciplinary guidelines have been developed jointly by dermatologists, rheumatologists and neurologists. While patients with PM, DM and NM are eligible for immunosuppressive treatment, IBM seems to be largely refractory to this approach. This illustrates that it is also essential to distinguish between myositis and other, non-inflammatory muscle -diseases. The following review article presents the current state-of-theart approach to the diagnostic workup and treatment of myositis.