Inflammatory myopathy

© 2017 Introduction Inflammatory myopathies are a heterogeneous group of acquired muscular disorders characterised by the presence of an inflammatory infiltrate in the muscle biopsy. Currently there are 4 main recognised clinical phenotypes, including dermatomyositis, polymyositis, inclusion body myositis and immune-mediated necrotising myopathy. Etiopathogenesis They are considered systemic diseases of apparent autoimmune origin, where the muscle biopsy detects infiltrating B and CD4+ T lymphocytes with endothelial deposit of C5b-9 membrane attack complex in dermatomyositis, CD8+ T cells/MHC-I complex in polymyositis and inclusion body myositis and rimmed vacuoles in inclusion body myositis. Muscle necrosis, the presence of macrophages and the MHC-I expression in muscle cells characterise immune-mediated necrotising myositis. Diagnosis and treatment Symptoms, muscle biopsy and immune profile are helpful tools to reach a correct diagnosis. Immunosuppressive therapies, intravenous immunoglobulins and biological agents, together with physical rehabilitation constitute the therapeutic arsenal to treat these conditions.