The pathogenesis of dermatomyositis

Summary This review looks at the many different factors thought to play a role in idiopathic inflammatory myopathies ( IIM ), concentrating mainly on the dermatomyositis ( DM ) subtype. Subject areas addressed include looking at the different clinical features of IIM , paying particular attention to the skin manifestations. There is a discussion around investigations needed with their perceived value, followed by a description of the immunohistochemical findings of DM . This review goes on to address other attributing factors such as genetic associations with the different subtypes of IIM , and environmental factors including infections, ultraviolet radiation and vitamin D deficiency and drugs. Finally, the potential immunopathogenesis of DM is summarized, looking at T cells, B cells, autoantibodies, dendritic cells, cytokines and nonimmune‐mediated endoplasmic reticulum stress.