Skin involvement in dermatomyositis

Dermatomyositis (DM) is a rare multisystem autoimmune disorder of adults and children that primarily affects skin and skeletal muscle. Classification systems of dermatomyositis, polymyositis, and the other idiopathic inflammatory myopathies focus primarily on features of muscle involvement. However, cutaneous disease does not always parallel muscle disease in its onset, activity, or response to therapy. This review will describe the distinct cutaneous clinical and histopathologic presentation of DM and the relation between these cutaneous findings, pathogenesis of DM, and serological subsets of DM.

This review discusses recent findings that have begun to elucidate the pathogenesis of DM, including polymorphism of tumor necrosis factor-alpha 308A allele and maternal fetal microchimerism. The recent description of other systemic diseases and drugs causing DM-like eruptions and the recognition that DM can resemble other common dermatoses highlights the need for a cutaneous biopsy to diagnose and distinguish the cutaneous features of DM. Once diagnosed, a number of noninvasive imaging modalities and new cutaneous assessment instruments can be used to follow and evaluate patients with DM.

Recognition of cutaneous and histopathologic findings in DM is essential for prompt and accurate diagnosis and treatment of DM.