Anti-SAE autoantibody in dermatomyositis: original comparative study and review of the literature
Juliette Demortier, Mathieu Vautier, O. Chosidow, Laure Gallay, D. Bessis, A. Bérezné, N. Cordel, J. Schmidt, Amar Smaïl, P. Duffau, M. Jachiet, É. Bégon, Jérémy Gottlieb, François Chasset, J. Graveleau, M. Marque, E. Cesbron, Amandine Forestier, S. Josse, Nicolas Kluger, Caroline Beauchêne, Y. Le Corre, Valentine Pagis, Aude Rigolet, Perrine Guillaume-Jugnot, François‐Jérôme Authier, Nelly Guilain, Nathalie Streichenberger, Sarah Léonard-Louis, Samia Boussouar, Océane Landon‐Cardinal, Olivier Benvéniste, Yves Allenbach
Abstract
OBJECTIVE: Among specific autoantibodies in DM, the anti-small ubiquitin-like modifier activating enzyme (SAE) antibody is rare. We aim to describe the clinical characteristics, cancer prevalence, and muscle pathology of anti-SAE-positive DM. METHODS: Patients with a diagnosis of DM and sera positive for the anti-SAE antibody were recruited from 19 centres in this retrospective observational study. The available muscular biopsies were reviewed. We conducted a comparison with anti-SAE-negative DM and a review of the literature. RESULTS: Of the patients in the study (n = 49), 84% were women. Skin involvement was typical in 96% of patients, with 10% having calcinosis, 18% ulceration and 12% necrosis; 35% presented with a widespread skin rash. Muscular disease affected 84% of patients, with mild weakness [Medical Research Council (MRC) scale 4 (3, 5)], although 39% of patients had dysphagia. Muscular biopsies showed typical DM lesions. Interstitial lung disease was found in 21% of patients, mainly with organizing pneumonia pattern, and 26% of patients showed dyspnoea. Cancer-associated myositis was diagnosed in 16% of patients and was responsible for the majority of deaths, its prevalence being five times that of the general population. IVIG therapy was administered to 51% of the patients during the course of the disease. Comparison with anti-SAE-negative DM (n = 85) showed less and milder muscle weakness (P = 0.02 and P = 0.006, respectively), lower creatinine kinase levels (P < 0.0001) and less dyspnoea (P = 0.003). CONCLUSION: Anti-SAE positive DM is a rare subgroup associated with typical skin features but a potentially diffuse rash, a mild myopathy. Interstitial lung disease defines an organizing pneumonia pattern. Cancer associated DM prevalence is five times that of the general population. TRIAL REGISTRATION: ClinicalTrials.gov, http://clinicaltrials.gov, NCT04637672.