Different faces of anti-melanoma differentiation-associated gene 5 antibody-positive myositis

Dermatomyositis with anti-melanoma differentiation-associated gene 5 (anti-MDA5) antibodies is a rare, poorly recognised and potentially life-threatening subtype of idiopathic inflammatory myopathies. Frequent amyopathic course, unique cutaneous lesions, symptoms interfering with other connective tissue diseases, and low awareness of the disease lead to a delay in establishing the proper diagnosis. Clinical presentations may differ among individuals, and three main patterns have been identified depending on the predominant symptoms and prognosis. Interstitial lung disease and vasculopathy contribute mostly to an unfavourable outcome. The study aimed to present different courses of anti-MDA5 myopathy and highlight the heterogenicity of the disease, based on real-life cases from one centre. This is also the first study to document renal involvement in the form of focal segmental glomerulosclerosis in patient with anti-MDA5 dermatomyositis. The review section broadly describes up-to-date knowledge on the subtypes of anti-MDA5 myopathy, thoroughly exploring its pathogenesis, clinical presentations and currently recommended standards of care.