[Idiopathic inflammatory myopathies]

Idiopathic inflammatory myopathies form a heterogeneous group of acquired inflammatory diseases afflicting striated muscles. The disease is frequently accompanied by systemic and organ involvement. Dermatomyositis, polymyositis, cancer associated myositis, immune mediated necrotizing myopathy, myositis in overlap syndromes, juvenile myositis and inclusion body myositis are the most frequently encountered subtypes. The basic manifestation is usually painless muscle weakness brought about by inflammation and by other immune changes at the impacted muscles. Enzymes of muscle origin and myoglobin are found elevated in the circulation. There are changes in electrical properties of muscle fibers detected by EMG. A majority of patients have autoantibodies against nuclear or cytoplasmic antigens in their serum. They are often very specific for these diseases and frequently found in association with particular clinical presentations. For some patients with dermatomyositis the increased incidence of cancer is significantly associated with anti-TIF1γ and anti-NXP2 autoantibodies. Differential diagnostics of inflammatory myopathies is often difficult. Misdiagnosis for a non-inflammatory myopathy is not rare and therefore a very thorough diagnostic approach is necessary. Therapy aims to suppression of autoimmune response using glucocorticoids and immunosuppressive drugs. In large part of patients the response to standard treatment is not sufficient and less common synthetic compounds, biological drugs or intravenous immunoglobulins need to be used. Most patients with inclusion body myositis has limited or no effect of any treatment.Key words: autoantibodies - autoimmunity - inflammation - myopathy - myositis - systemic disease.