Hum, Ryan MalcolmRyan MalcolmHumLilleker, James BJames BLillekerLamb, Janine AJanine ALambOldroyd, Alexander G SAlexander G SOldroydWang, GuochunGuochunWangWedderburn, Lucy RLucy RWedderburnDiederichsen, Louise PLouise PDiederichsenSchmidt, JensJensSchmidtDanieli, Maria GiovannaMaria GiovannaDanieliOakley, PaulaPaulaOakleyGriger, ZoltanZoltanGrigerPhuong, Thuy Nguyen ThiThuy Nguyen ThiPhuongKodishala, ChanakyaChanakyaKodishalaMercado, Monica Vazquez-DelMonica Vazquez-DelMercadoAndersson, HelenaHelenaAnderssonDe Paepe, BoelBoelDe PaepeDe Bleecker, Jan LJan LDe BleeckerMaurer, BrittaBrittaMaurerMcCann, LizaLizaMcCannPipitone, NicoloNicoloPipitoneMcHugh, NeilNeilMcHughNew, Robert PaulRobert PaulNewOllier, William EWilliam EOllierKrogh, Niels SteenNiels SteenKroghVencovsky, JiriJiriVencovskyLundberg, Ingrid EIngrid ELundbergChinoy, HectorHectorChinoy2024-10-252024-10-252024-08-01https://boris-portal.unibe.ch/handle/20.500.12422/169944OBJECTIVES To compare clinical characteristics, including the frequency of cutaneous, extramuscular manifestations, and malignancy, between adults with anti-synthetase syndrome (ASyS) and dermatomyositis (DM). METHODS Using data regarding adults from the MYONET registry, a cohort of DM patients with anti-Mi2/-TIF1ɣ/-NXP2/-SAE/-MDA5 autoantibodies, and a cohort of ASyS patients with anti-tRNA synthetase autoantibodies (anti-Jo1/-PL7/-PL12/-OJ/-EJ/-Zo/-KS) were identified. Patients with DM sine dermatitis or with discordant dual autoantibody specificities were excluded. Sub-cohorts of patients with ASyS with or without skin involvement were defined based on presence of DM-type rashes (heliotrope rash, Gottron's papules/sign, violaceous rash, shawl sign, V sign, erythroderma, and/or periorbital rash). RESULTS In total 1,054 patients were included (DM, n = 405; ASyS, n = 649). In ASyS cohort, 31% (n = 203) had DM-type skin involvement (ASyS-DMskin). A higher frequency of extramuscular manifestations, including Mechanic's hands, Raynaud's phenomenon, arthritis, interstitial lung disease, and cardiac involvement differentiated ASyS-DMskin from DM (all p< 0.001), whereas higher frequency of any of four DM-type rashes: heliotrope rash (n = 248, 61% vs n = 90, 44%), violaceous rash (n = 166, 41% vs n = 57, 9%), V sign (n = 124, 31% vs n = 28, 4%), and shawl sign (n = 133, 33% vs n = 18, 3%) differentiated DM from ASyS-DMskin (all p< 0.005). Cancer-associated myositis (CAM) was more frequent in DM (n = 67, 17%) compared with ASyS (n = 21, 3%) and ASyS-DMskin (n = 7, 3%) cohorts (both p< 0.001). CONCLUSION DM-type rashes are frequent in patients with ASyS; however, distinct clinical manifestations differentiate these patients from classical DM. Skin involvement in ASyS does not necessitate increased malignancy surveillance. These findings will inform future ASyS classification criteria and patient management.enAntisynthetase syndrome MYONET Raynaud’s phenomenon cutaneous dermatomyositis epidemiology extramuscular malignancy rashes skin600 - Technology::610 - Medicine & healtharticle10.48350/1862713769898710.1093/rheumatology/kead481