Idiopathic inflammatory myopathies in dermatological practice (part II)

The aim of this article is to present inflammatory myopathies with skin involvement other than dermatomyositis, mainly scleromyositis and mixed connective tissue disease (MCTD). Scleromyositis, observed in adults and children, is characterized by overlapping features of scleroderma and poly- or dermatomyositis variously pronounced in the course of the disease. The immunological marker of this syndrome is the so-called PM-Scl antibody, which is of diagnostic value and allows one to differentiate scleromyositis from MCTD, systemic scleroderma and dermatomyositis. Another overlap syndrome, MCTD combines features of scleroderma, SLE and myositis and, in some cases, also rheumatoid arthritis and Sjogren’s syndrome. The disease is observed in adults and children and has a rather protracted course. Characteristic for MCTD is high titre of anti-U1RNP antibody. Skin involvement may also be observed in inflammatory myopathy coexisting with interstitial lung disease and antibodies directed to aminoacyl tRNA synthetase – called synthetase syndrome. Inflammatory myopathies with scleroderma-like or lupus-like skin changes should be distinguished from cases of systemic sclerosis and SLE, in which muscle involvement may also be present. The proper diagnosis and differentiation of inflammatory myopathies is necessary for starting appropriate therapy.