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Systemic autoimmune myopathies (SAMs) are rare diseases that lead to muscle inflammation and may be associated with a variety of systemic manifestations. Although there is great heterogeneity in the spectrum of extra-muscular involvement in SAMs, interstitial lung disease (ILD) is the most frequent lung manifestation. SAM-related ILD (SAM-ILD) presents significant variations according to geographic location and temporal trends and is associated with increased morbidity and mortality. Several myositis autoantibodies have been discovered over the last decades, including antibodies targeting aminoacyl-tRNA synthetase enzymes, which are associated with a variable risk of developing ILD and a myriad of other clinical features. In this review, the most relevant topics regarding clinical manifestations, risk factors, diagnostic tests, autoantibodies, treatment, and prognosis of SAM-ILD are highlighted. We searched PubMed for relevant articles published in English, Portuguese, or Spanish from January 2002 to September 2022. The most common SAM-ILD patterns are nonspecific interstitial pneumonia and organizing pneumonia. The combination of clinical, functional, laboratory, and tomographic features is usually sufficient for diagnostic confirmation, without the need for additional invasive methods. Glucocorticoids remain the first-line treatment for SAM-ILD, although other traditional immunosuppressants, such as azathioprine, mycophenolate, and cyclophosphamide have demonstrated some efficacy and, therefore, have an important role as steroid-sparing agents.

Background: Currently, only a few retrospective cohort or cross-sectional studies have described the general characteristics of Brazilian patients with classical dermatomyositis (DM). In contrast, we aimed to longitudinally assess a large sample of these patients, and several myositis autoantibodies., Methods: This single-center longitudinal study included 91 Brazilian adults with defined DM (EULAR/ACR 2017) who underwent follow-up appointments in our tertiary center from 2012 to 2021. Myositis autoantibody analysis was performed using a commercial kit., Results: The mean age of the patients was 47.3 ± 15.4 years, with a predominance of female (67.0%) and White (81.3%) patients. As an initial treatment, 76.9% of the patients received methylprednisolone pulse therapy, 59.3% received intravenous immunoglobulin, and 54.9% received both drugs. The median follow-up duration was 44 months (interquartile 17-67) months. There were 92 severe episodes of infection, and neoplasms were identified in 20 patients (22.0%). Hypertension was identified in 46.2% of patients, whereas diabetes mellitus and myocardial infarction occurred in 19.8% and 4.4%, respectively. Nine patients died during the follow-up. At the last visit, one-third of the patients had disease activity, half had a complete clinical response, and one-fifth were in disease remission. In a univariate logistic regression, anti-aminoacyl-tRNA synthetase antibodies (n = 13) were associated with interstitial lung disease, "mechanic's hands", and anti-Ro-52, and had an inverse association with "V"-neck and "shawl" signs. Anti-MDA-5 (n = 10) were associated with male gender, digital ulcers, vasculitis, arthritis, anti-Ro-52, and active disease. Anti-Ro-52 (n = 26) were associated with "mechanics' hands", arthritis, interstitial lung disease, anti-tRNA synthetases, and anti-MDA-5. No association was found for anti-Mi-2 (n = 10)., Conclusions: This study shows the general profile of a significant sample of Brazilian patients with DM as well as the association of some antibodies with clinical and laboratory manifestations of this myositis., (© 2022. The Author(s).)