ORIGINAL ARTICLE The clinical phenotype of patients positive for antibodies to myositis and myositis-related disorders S. G. Gofrit 1 & H. Yonath 1,2,3 & M. Lidar 3,4 & Y. Shoenfeld 3,4,5 & S. Kivity 1,3,4,6 Received: 14 December 2017 /Revised: 2 February 2018 /Accepted: 7 February 2018 # International League of Associations for Rheumatology (ILAR) 2018 Abstract Inflammatory myopathies are a clinically diverse group of diseases, in which the detection of particular autoantibodies may facilitate diagnosis, treatment, and prognosis. The aim of this report is to summarize our experience with specific autoantibody testing in patients with inflammatory myopathies. Data were collected over the last decade in the Autoimmune Center of the Sheba Medical Center, a tertiary referral hospital. Data regarding patients’ positive for autoantibodies against Jo-1, PL-7, PL-12, SRP, Mi-2, Ku, and PM-Scl antigens were retrospectively collected. Patient demographics, clinical characteristics, and mortality were recorded. Descriptive statistics (mean, standard deviation, frequency, and percentage) were calculated. A total of 507 patients were surveyed for sclero-poly-synthetase antibodies, as part of the diagnostic workup of myositis/myalgia or interstitial lung disease. Forty-three patients were found positive for one or more of the abovementioned antibodies, and 23 of them (53.49%) had interstitial lung disease (ILD). Four patients were positive for anti-PL-7, three of them had ILD and Raynaud’ s phenomenon. Five patients were positive for anti-Ku, and four of them had both arthritis and Raynaud’ s phenomenon. Nine patients were positive for anti-Mi-2, and six of them were given diagnosed with dermatomyositis. Ten patients were positive for anti-SRP, and six of them had cancers of various types. Our results reiterate the previously recognized associations between anti-Mi-2 and dermato- myositis, anti-Ku and Raynaud’s phenomenon, and between anti-PL-7 and ILD. In addition, our data support an association between anti-SRP autoantibody positivity and malignancy, which calls for further investigation. Keywords Anti-synthetase . Dermatomyositis . Interstitial lung disease . Myositis . Polymyositis Introduction The inflammatory myopathies (IMs) are a group of auto- immune diseases with various, partially overlapping clin- ical presentations that share a common feature of immune-mediated muscle injury. Due to difficulties in definition and diagnostic abilities, inflammatory myopa- thies epidemiology differs among studies. In a review by Meyer et al., the incidence of inflammatory myopathies varied from 1.16 to 19 cases per million per year with a prevalence of 2.4 to 33.8 cases per 100,000 [1]. In a study by Dobloug et al. conducted in Norway, the point preva- lence of polymyositis (PM) and dermatomyositis (DM) was 8.7 cases per 100,000, and the annual incidence ranged from 6 to 10 cases per 1,000,000 [2]. Point prev- alence of inclusion body myositis (IBM) in Norway was 33 cases per 1,000,000 [3]. S. G. Gofrit and H. Yonath contributed equally to this work. * S. Kivity kivitys@gmail.com 1 Department of Medicine A, Sheba Medical Center, 5262000 Tel Hashomer, Israel 2 Danek Gertner Institute of Human Genetics, Tel Hashomer, Israel 3 Sackler School of Medicine, Ramat Aviv, Israel 4 The Zabludowicz Center for Autoimmune Diseases, Tel-Hashomer, Israel 5 Incumbent of the Laura Schwarz-Kip Chair for Research of Autoimmune Diseases, Sackler Faculty of Medicine, Tel-Aviv University, Tel Aviv-Yafo, Israel 6 The Dr. Pinchas Borenstein Talpiot Medical Leadership Program 2013 and Sheba Medical Center, Tel-Hashomer, Israel Clinical Rheumatology https://doi.org/10.1007/s10067-018-4032-3