Cutaneous features of classic dermatomyositis and amyopathic dermatomyositis.

This review will focus on the work that has been reported over the past year attempting to better characterize the overall clinical significance of the cutaneous manifestations of dermatomyositis (DM). It will be organized under two headings--amyopathic dermatomyositis (ADM) and classic dermatomyositis (CDM). The distinction between these two clinical phenotypes of DM is the absence of clinically-evident muscle disease in ADM; to date it has not been possible to distinguish the cutaneous manifestations of ADM and CDM. The term hypomyopathic DM is introduced to distinguish those patients with the hallmark skin changes of DM and no clinical evidence of muscle disease who are found to have subclinical evidence of myositis upon electrophysiologic, histopathologic, and/or radiologic evaluation. Recent issues that have been raised concerning the definition, classification, epidemiology, etiopathogenesis, clinical features, treatment, differential diagnosis, and prognosis of ADM and CDM are discussed. In view of the irrefutable evidence documenting the existence of ADM for 20 years or more, the term idiopathic inflammatory dermato-myopathies may be more appropriate for this group of clinical disorders than the currently used designation, idiopathic inflammatory myopathies.