Predictive factors for anti-MDA5 antibody in patients with dermatomyositis: a retrospective multicenter study.

BACKGROUND AND OBJECTIVES: Melanoma differentiation-associated gene 5 antibody (anti-MDA5) in dermatomyositis (DM) is associated with rapidly progressive interstitial lung disease and poor prognosis. Early diagnosis is key to improving the prognosis of these patients. The aim was to confirm cutaneous characteristics in patients with anti-MDA5 dermatomyositis and to explore new diagnostic markers for the presence of anti-MDA5 (anti-MDA5+ ). PATIENTS AND METHODS: A multicenter cross-sectional retrospective cohort study of 124 patients diagnosed with DM, of which 37 were anti-MDA5+ . Demographic data, laboratory data, and clinical manifestations were collected. RESULTS: Anti-MDA5+ DM is characterized by a distinct mucocutaneous phenotype that includes oral lesions, alopecia, mechanic's hands, palmar and dorsal papules, palmar erythema, vasculopathy, and skin ulceration. We found vasculopathy and digit tip involvement very frequently in anti-MDA5+ patients (p <0.001), being a diagnostic marker of anti-MDA5+ (OR, 12.355; 95% CI 2.850-79.263; p  =  0.012 and OR, 7.447; 95% CI 2.103-46.718; p  =  0.004, respectively). The presence of ulcers deserves special mention, especially in anti-MDA5+ patients, because in our cohort, up to 97% of the anti-MDA5+ patients had ulcers. CONCLUSIONS: In patients with suspected DM with digit tip involvement or vasculopathy, the presence of anti-MDA5 antibodies must be ruled out, as it may be a clinical predictor.