POS0840 MELANOMA DIFFERENTIATION-ASSOCIATED GENE 5 ANTIBODY (ANTI-MDA5) DERMATOMYOSITIS: CLINICAL FEATURES AND OUTCOME IN A RACIALLY DIVERSE PATIENT COHORT

BackgroundMelanoma differentiation associated gene 5 antibody (anti-MDA5) dermatomyositis, is an idiopathic inflammatory musculoskeletal disorder with specific phenotypic manifestations of rapidly progressing interstitial lung disease (RP-ILD) and ulcerative skin lesions, with or without muscle involvement. [1] There is currently a lack of consensus and guidelines on early diagnosis and timely escalation of therapy to avoid untoward outcomes.ObjectivesTo identify distinguishing clinical and laboratory features to assess disease progression amongst individuals with anti- MDA5 dermatomyositis based on the serologic, histopathologic, and radiographic status. We identified and compared the disease phenotype in a racially diverse juvenile and adult population with anti-MDA5 dermatomyositis.MethodsAfter Institutional review board approval, we queried the electronic health record at the Montefiore Medical Center, NY, and identified a total of 194 dermatomyositis patients. We included 21 dermatomyositis patients with MDA5 antibody. We performed a retrospective chart review to extract clinical data and analyzed data using Fischer’s exact test.ResultsOf the 21 dermatomyositis patients with anti-MDA5, 12 adult patients represented 8% of all adult dermatomyositis cases (12/148) and 9 patients represented 19 % of the pediatric dermatomyositis cases (9/46). There was a 2:1 female to male predominance in both groups.In adults, the mean age of disease onset was 45.2 years (SD 14.4 years). Nine ILD cases were noted, of which 2 were RP-ILD. The presence of the Ro52 antibody was associated with rapid disease progression. In children, the mean age of onset was 6.6 years (SD 4.9 years). All children had muscle weakness, with only 5 having ILD. Myositis was noted to be more prevalent in the pediatric population, compared to adults (9/9 Vs 4/12 cases; P=0.005).In this patient cohort, ILD was statistically significant between the African American population (9/10 cases) and non-African American population (5/11 cases), p=0.03, of these 3 African American cases had RP-ILD with mortality. The combined mortality rate of 14.2% was superior to 40-60% reported in the literature. [2]ConclusionAnti MDA5 dermatomyositis is relatively rare and difficult to diagnose. In this study, the general disease characteristics of our cohort were similar in both adult and pediatric patients except for myositis, which was more common in the pediatric population. The incidence of ILD by contrast was higher in the adults, especially in the African American population who had worse outcomes. The rapid escalation of therapy and use of rituximab may have improved our outcomes over historic controls. Controlled studies are needed to evaluate patients with anti-MDA5 dermatomyositis for appropriate treatment interventions and to avoid untoward outcomes.References[1]Fiorentino D, et al. The mucocutaneous and systemic phenotype of dermatomyositis patients with antibodies to MDA5; J Am Acad Dermatol. 2011;65(1):25-34. doi:10.101[2]Koga T, et al. The diagnostic utility of anti-melanoma differentiation-associated gene 5 antibody testing for predicting the prognosis of Japanese patients with DM. Rheumatology. 2012;51(7):1278-1284. doi:10.1093Figure 1.Disclosure of InterestsNone declared