Dermatomyositis, Antisynthetase Syndrome and Immune-Mediated Necrotising Myopathy

Today, idiopathic inflammatory myopathies are categorised more precisely based on clinical findings, histopathological aspects, and autoantibody status, e. g., into dermatomyositis, antisynthetase syndrome, and immune-mediated necrotising myopathy (IMNM). These mostly present with proximal muscle weakness, although the disease can also occur in an amyopathic form in some cases. Dermatomyositis patients may present with varying manifestations, depending on the antibody status, with interstitial lung disease (ILD) being the most common extramuscular presentation. Especially in the presence of concomitant risk factors such as anti-TIF1 gamma or anti-NXP2-positive antibodies, a tumour screening should be performed in adult patients. IMNMs are known as being associated with exposure to statins, but it should be borne in mind that statin exposure is not a precondition for the development of an IMNM. Antisynthetase syndrome usually presents with a triad of myositis, arthritis, and ILD. Here, too, the classical triad is not necessarily present. As regards therapeutic approaches, the three entities do not initially differ. An initial steroid therapy is started and complemented by steroid-sparing maintenance therapy, which depends on the severity and organ involvement of the disease. Physiotherapy and, if needed, occupational therapy and logopaedics are integral parts of the treatment and should be initiated at an early point in time.