Background: Although melanoma differentiation associated (MDA)-5 autoantibodies have been widely explored in dermatomyositis (DM), most studies have relied on MDA-5 autoantibody testing performed in research settings, rather than the now-available commercial laboratory tests. Aim: To characterize the clinical and histopathological data in patients with DM and circulating MDA-5 autoantibodies, as defined by commercially available testing. Methods: This was a retrospective review of patients with DM who underwent MDA-5 antibody testing. All available skin biopsy slides were reviewed. Results: Cutaneous features more prevalent in MDA-5-positive DM included Raynaud phenomenon (RP) (P < 0.001), cutaneous ulcerations (P = 0.01), mechanic hands (P < 0.02), palmar papules (P < 0.01), oral ulcers (P = 0.024) and alopecia (P = 0.03). Joint and pulmonary involvement were more common in patients with MDA-5-positive DM (both P < 0.001) as was dysphagia (P < 0.01). Myopathy (P = 0.4) and malignancy (P = 0.34) were not statistically different between the cohorts. Vasculopathy was more common in MDA-5-positive DM (P < 0.01), while spongiosis was less common (P < 0.02). Conclusion: This study not only confirms some known associations between disease manifestations and MDA-5 autoantibody status, as determined by commercially available tests, but also identifies new associations, including RP and dysphagia.
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