Date: Monday, October 22, 2018
Session Type: ACR Poster Session B
Session Time: 9:00AM-11:00AM
Background/Purpose: Dermatomyositis (DM) is a heterogenous group of diseases ranging from skin limited disorders to non-specific auto-immune diseases with patients suffering from additional extra-cutaneous manifestations. The myositis specific antibody (Ab) anti-melanoma differentiation-associated gene 5 antibody (MDA5+) delineates a group of patients with a DM skin rash, arthralgia and an interstitial lung disease (ILD), sometimes severe because rapidly progressive (RP-ILD), whereas clinical signs of myositis are absent.
The variety and the predominance of the extra-muscle manifestations question the term of ‘myositis specific Ab’ and the homogeneity of the related disease. Precising the clinical phenotype, as well as the prognosis of MDA5+ patients is necessary to improve the management of this severe disease.
Methods: MDA5+ patients were defined as patients with a DM skin rash and/or arthralgia and/or ILD without other aetiology in presence of anti-MDA5 Ab. Clinical, laboratory and imaging data were collected (multicentric study). As control, a cohort of anti-MDA5- myositis patients was used. Unsupervised analyses were performed either on both groups (anti-MDA5+ and control) or on anti-MDA5+ patients only.
Results: Anti-MDA5+ patients’ (n=121) characteristics were in line with the previous reports. Patients were mainly female, 49 years old [34-58], with a DM skin rash (87.5%) and signs of vasculopathy (Raynaud phenomenon, skin ulcers, calcinosis and/or digital necrosis), with ILD (77%; RP-ILD, 32.7%) and with arthralgia (69%). Death occurred in 25.4% of cases.
MDA5+ patients’ phenotype was clearly distinct from controls (n=323). Unsupervised analysis (without including data of the serological status) showed clearly two clusters. One was characterized by more frequent DM skin rash, skin ulcers, calcinosis, mechanics hands, ILD, arthralgia/arthritis and patients with a higher mortality rate. In this cluster 87% of patients were MDA5+.
Within MDA5+ group, analysis showed three clusters. As previously reported, one corresponds to patients with RP-ILD (ILD 100% and RP-ILD 95%; p<0.0001), but mechanics’ hands were frequent (65%; p<0.0001). Two new subgroups were identified. One is an ‘athro-cutaneo-form’ (arthralgia/arthritis, 85%; p<0.0001; RP-ILD, 9.5%; p<0.0001) and another is a ‘vasculo-cutaneo-muscular-form’ corresponding to male patients (71.4%; p<0.0001) with a severe skin vasculopathy (frequent Raynaud phenomenon, skin ulcers, digital necrosis and calcinosis) and with frequent sign of myositis (weakness 71.3%; p<0.0001).
The outcome depends on the form of the disease. A very high mortality rate is observed in the ‘RP-ILD form’ (65%), in contrast to the good outcome in the ‘athrocutaneo-form’ (0% of mortality) and intermediate one in the ‘vasculo-dermatomyo-form’ (19% of mortality).
Conclusion: MDA5+ patients are a distinct group from myositis patients, characterised by a systemic syndrome composed by three different entities with different outcomes.
To cite this abstract in AMA style:Allenbach Y, Uzunhan Y, Toquet S, Leroux G, Gallay L, Rigolet A, Hervier B, Champtiaux N, Vautier M, Guillaume P, Limal N, Meyer A, Deligny C, Bonnotte B, Devilliers H, Audia S, Samson M, Servettaz A, Costedoat N, Saadoun D, diot E, Berezne A, Mékinian A, Mariampillai K, Nunes H, Benveniste O. Moving from Dermatomyositis Associated with Anti-Melanoma Differentiation-Associated Gene 5 Antibody to Anti-Melanoma Differentiation-Associated Gene 5 Syndrome [abstract]. Arthritis Rheumatol. 2018; 70 (suppl 10). https://acrabstracts.org/abstract/moving-from-dermatomyositis-associated-with-anti-melanoma-differentiation-associated-gene-5-antibody-to-anti-melanoma-differentiation-associated-gene-5-syndrome/. Accessed January 23, 2020.
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