AB0675 Anti-mda5 positive dermatomyositis: an emerging entity

Background Hypo or amyopathic dermatomyositis (DM) represent about 20% of the classic DM. Melanoma differentiation-associated gene 5 antibody or anti-MDA5 antibody, formerly known as anti-CADM140 antibody, has been reported in the last decade. This antibody is detected in more than 50% of patients with hypo or amyopathic DM and it has specific features such as the presence of ulcerative vascular lesions and rapid progression of the interstitial lung disease. Objectives To report anti-MDA5 positive DM cases diagnosed at a university county hospital, between 2012 and 2016. Methods Design: Retrospective descriptive study. Location: University county hospital. Reference area: ?350.000 inhabitants. Clinical manifestations, analytical results, diagnostic approach, treatment administered and follow-up have been exposed. Results We report four anti-MDA5 positive DM with a mean age at diagnosis of 54 years (35–77). Caucasian origin in 2 men and Maghreb origin in 2 women. They had no relevant medical history neither neoproliferative process was detected. ANA were negative and CK values were normal in all the cases. Nailfold capillaroscopy was characteristic of DM pattern. Case B did not present cutaneous manifestations and he was diagnosed as anti-MDA5 DM after his death. Discussion B and C cases showed abnormal heart rhythm that could be related to myocardial involvement, as suggested in a recent publication of anti-MDA5 DM (1). In case C, sinus tachycardia was resolved with the clinical response to treatment. In the literature reviewed, anti-MDA5 positive DM has been reported as a dermato-pulmonary syndrome, but probably the clinical profile of these patients remains to be defined. In our cases, one of them did not present skin lesions and another case did not develop pulmonary involvement 18 months after the diagnosis. Conclusions Keep in mind anti-MDA5 antibody in patients with cutaneous manifestations of DM with vasculopathy lesions, minimal or absent muscular disease, heart rhythm abnormalities not explained by other causes and/or rapidly progressive pulmonary involvement. Anti-MDA5 positive DM may have a poor response to treatment and fatal outcome. It remains to be seen if early diagnosis could improve the life expectancy of these patients. References J Eur Acad Dermatol Venereol 2014; 28: 1097–102. Disclosure of Interest None declared