Dermatomyositis (DM) is a multifactorial chronic autoimmune disorder with characteristic skin changes and involvement of different organ systems, including the muscles, blood vessels, joints, esophagus, and lungs. In terms of epidemiology, DM affects both children and adults. It is most often observed beyond the age of 40, but there is also a peak of incidence between 5 and 12 years of age. The current paradigm describing the pathophysiology of DM is an autoimmune attack on affected organs that is triggered by environmental factors such as UV exposure, drugs, infection, and lifestyle decisions in genetically susceptible individuals. Importantly, DM is also regarded as a paraneoplastic phenomenon, as cancer may precede, occur concurrently with, or follow the development of the clinical signs of DM. The cutaneous manifestations of DM can be categorized as pathognomonic, characteristic, compatible, less common, rare, recent, and nonspecific. The treatment of DM is a difficult task due to its rarity, its multiple phenotypes, and the fact that the disease may affect multiple organs and is commonly treatment-refractory. The lack of randomized, controlled intervention trials and, until recently, the insufficiency of validated, clinically meaningful outcome instruments in part contribute to the lack of approved treatments.
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