Idiopathic inflammatory myopathies (IIMs) are a group of autoimmune rheumatic diseases affecting the skeletal muscles, skin, and other organs. There is substantial variety in the presentation of IIMs, and myositis-specific autoantibodies (MSAs) have been linked with specific phenotypes. The anti-melanoma differentiation-associated gene 5 antibody (anti-MDA-5) has been associated with a lower incidence of myositis and an increased risk of rapidly progressive interstitial lung disease (RP-ILD) with a potentially fatal course [1]. Anti-MDA-5 dermatomyositis was first described in eight Japanese patients in 2005 who presented with clinically amyopathic dermatomyositis (CADM) and RP-ILD [2]. Thus far, most of the literature has described primarily non-Hispanic populations [3,4].

Given that it is not uncommon for rheumatic diseases to have unique presentations based on race or ethnicity, it is important to characterize this phenotype in diverse populations. This case series will highlight the clinical characteristics of anti-MDA-5 dermatomyositis in a primarily Hispanic population of urban Los Angeles, California, which has heretofore not been described in the setting of this specific IIM phenotype.