Inflammatory Myopathies with Cutaneous Involvement: from Diagnosis to Therapy.

The group of idiopathic inflammatory myopathies (IIM) include various disorders of skeletal muscles with or without skin involvement. The most common types are dermatomyositis (DM), polymyositis (PM), inclusion body myositis (IBM) and necrotizing autoimmune myopathy (NAM). Dermatomyositis subdivides into various clinical forms such as juvenile, amyopathic or paraneoplastic dermatomyositis, scleromyositis, overlap or anti-synthetase syndromes, etc. Recently, numerous new antibodies defining the characteristic clinical phenotype have been described as anti-MDA5 antibodies associated with interstitial lung disease and amyopathic dermatomyositis or anti-TIF1γ antibodies as markers for paraneoplastic dermatomyositis. Moreover, new clinical entities as drug-induced dermatomyositis are presumed, since some medications may induce, or trigger inflammatory myopathies. Knowledge of the complex methods and techniques required to diagnose the disease is of great importance in clinical practice. The variety of clinical variants needs diagnosis because of the differing prognosis and therapeutic modalities.