The polymorphous spectrum of dermatomyositis: classic features, newly described skin lesions, and rare variants.

Dermatomyositis belongs to a group of rare autoimmune diseases characterized by a variable degree of skin symptoms and myopathy. The clinically diagnostic hallmarks of dermatomyositis are heliotrope rash, Gottron's papules and weakness of the proximal muscles. Along with pathognomonic, characteristic, and compatible cutaneous features, several uncommon and rare skin manifestations have been reported. In addition, new skin lesions have been described in dermatomyositis patients. Furthermore, rare clinical subtypes of dermatomyositis have been reported in the literature, including Wong-type dermatomyositis, characterised by the coexistence of dermatomyositis and pityriasis rubra pilaris with hyperkeratotic, erythematous, follicular confluent papules on the back of the hands along the bony prominences. In addition, plenty of autoantibody subsets have been recently described that are related to distinct clinical features and systemic involvement, such as anti-MDA5 autoantibodies. We reviewed the English- and German-language scientific literature using the key words "dermatomyositis", "autoantibodies", and "clinical features", alone or in combination, focusing on particular cutaneous symptoms and their association with defined autoantibody profiles. Furthermore, we focused on rare subtypes of dermatomyositis, unusual clinical features, and recently described skin lesions.