ObjectivesThe predominance of extramuscular manifestations (e.g., skin rash, arthralgia, interstitial lung disease [ILD]) as well as the low frequency of muscle signs in anti–melanoma differentiation-associated gene 5 antibody–positive (anti-MDA5+) dermatomyositis caused us to question the term myositis-specific antibody for the anti-MDA5 antibody, as well as the homogeneity of the disease.MethodsTo characterize the anti-MDA5+ phenotype, an unsupervised analysis was performed on anti-MDA5+ patients (n = 83/121) and compared to a group of patients with myositis without anti-MDA5 antibody (anti-MDA5−; n = 190/201) based on selected variables, collected retrospectively, without any missing data.ResultsWithin anti-MDA5+ patients (n = 83), 3 subgroups were identified. One group (18.1%) corresponded to patients with a rapidly progressive ILD (93.3%; p < 0.0001 across all) and a very high mortality rate. The second subgroup (55.4%) corresponded to patients with pure dermato-rheumatologic symptoms (arthralgia; 82.6%; p < 0.01) and a good prognosis. The third corresponded to patients, mainly male (72.7%; p < 0.0001), with severe skin vasculopathy, frequent signs of myositis (proximal weakness: 68.2%; p < 0.0001), and an intermediate prognosis. Raynaud phenomenon, arthralgia/arthritis, and sex permit the cluster appurtenance (83.3% correct estimation). Nevertheless, an unsupervised analysis confirmed that anti-MDA5 antibody delineates an independent group of patients (e.g., dermatomyositis skin rash, skin ulcers, calcinosis, mechanic's hands, ILD, arthralgia/arthritis, and high mortality rate) distinct from anti-MDA5− patients with myositis.ConclusionAnti-MDA5+ patients have a systemic syndrome distinct from other patients with myositis. Three subgroups with different prognosis exist.

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IMPORTANCEEvidence for the long-term efficacy and safety of anti-tumor necrosis factor α agents (anti-TNF) in treating cutaneous sarcoidosis is lacking.OBJECTIVE To determine the efficacy and safety of anti-TNF in treating cutaneous sarcoidosis in a large observational study.DESIGN, SETTING, AND PARTICIPANTS STAT (Sarcoidosis Treated with Anti-TNF) is a French retrospective and prospective multicenter observational database that receives data from teaching hospitals and referral centers, as well as several pneumology, dermatology, and internal medicine departments. Included patients had histologically proven sarcoidosis and received anti-TNF between January 2004 and January 2016. We extracted data for patients with skin involvement at anti-TNF initiation. MAIN OUTCOMES AND MEASURESResponse to treatment was evaluated for skin and visceral involvement using the ePOST (extra-pulmonary Physician Organ Severity Tool) severity score (from 0 [not affected] to 6 [very severe involvement]). Epidemiological and cutaneous features at baseline, efficacy, steroid-sparing, safety, and relapses were recorded. The overall cutaneous response rate (OCRR) was defined as complete (final cutaneous ePOST score of 0 or 1) or partial response (ePOST drop Ն2 points from baseline but >1 at last follow-up).RESULTS Among 140 patients in the STAT database, 46 had skin involvement. The most frequent lesions were lupus pernio (n = 21 [46%]) and nodules (n = 20 [43%]). The median cutaneous severity score was 5 and/or 6 at baseline. Twenty-one patients were treated for skin involvement and 25 patients for visceral involvement. Reasons for initiating anti-TNF were failure or adverse effects of previous therapy in 42 patients (93%). Most patients received infliximab (n = 40 [87%]), with systemic steroids in 28 cases (61%) and immunosuppressants in 32 cases (69.5%). The median (range) follow-up was 45 (3-103) months. Of the 46 patients with sarcoidosis and skin involvement who were treated with anti-TNF were included, median (range) age was 50 (14-78) years, and 33 patients (72%) were women. The OCRR was 24% after 3 months, 46% after 6 months, and 79% after 12 months. Steroid sparing was significant. Treatment was discontinued because of adverse events in 11 patients (24%), and 21 infectious events occurred in 14 patients (30%). Infections were more frequent in patients treated for visceral involvement than in those treated for skin involvement (n = 12 of 25 [48%] vs n = 2 of 21 [9.5%], respectively; P = .02). The relapse rate was 44% 18 months after discontinuation of treatment. Relapses during treatment occurred in 35% of cases, mostly during anti-TNF or concomitant treatment tapering.CONCLUSIONS AND RELEVANCE Anti-TNF agents are effective but suspensive in cutaneous sarcoidosis. The risk of infectious events must be considered.