Patients with anti-small ubiquitin-like modifier activating enzyme-positive dermatomyositis resembling antisynthetase syndrome with poor prognosis: a bicentric international retrospective study and literature review.

Objective: This study aimed to describe adult Brazilian and Japanese patients with anti-small ubiquitin-like modifier activating enzyme (SEA)-positive dermatomyositis (DM), as there are few studies in the literature. A literature review was also conducted.

Methods: This bicentric international retrospective study, conducted between 2012 and 2023, included patients with anti-SAE-positive DM (2017 European League Against Rheumatism/American College of Rheumatology classification criteria). All demographic features and clinical, laboratory, therapeutic, and follow-up data were collected from Brazilian and Japanese centers using pre-standardized and parameterized information.

Results: We included 17 adult patients with a median age of 65 (56-76) and a predominance of females (82.4%). Constitutional symptoms at baseline were present in 58.8% of the patients. In addition to classical cutaneous DM lesions, one-third of the patients had myalgia and significant muscle weakness, whereas half presented with dysphagia, interstitial lung disease, and joint manifestations. The first-line treatment consisted of intravenous methylprednisolone and immunoglobulin pulse therapy in 41.2% and 28.6% of the patients, respectively. The median follow-up duration was 20 (13-74) months; at the last medical evaluation, half had active disease and were still using oral glucocorticoids (median dosage, 10.0 mg/day). Approximately one-fifth to one-third of the patients were diagnosed with different types of cancer, had severe infections, or died.

Conclusions: Patients with anti-SAE-positive DM not only resemble the phenotype of antisynthetase syndrome but are also associated with a poor prognosis.