Clinical importance of anti-Ro52 antibody in polymyositis and dermatomyositis.

Objectives: To clarify the clinical features of anti-Ro52 antibody (Ab)-positive polymyositis (PM)/dermatomyositis (DM).

Methods: We retrospectively examined the clinical features and status of anti-Ro52 Abs in patients with PM/DM admitted to the University of Tsukuba Hospital between January 2019 and February 2023. We compared the anti-Ro52 Ab-positive and anti-Ro52 Ab-negative groups.

Results: A total of 40 patients were selected and analysed. Twenty-three cases were PM, and 17 cases were DM (including six clinically amyopathic DM). Twenty-two cases were positive for anti-Ro52 Ab, 14 for anti-ARS Ab, and 6 for anti-MDA5 Ab. Interstitial lung disease was detected in 29 cases, nine of which were rapidly progressive. Glucocorticoid-resistant cardiomyopathy was detected in six cases. Of the 22 anti-Ro52 Ab-positive cases, only 3 were single-positive and the remaining 19 cases simultaneously had other autoantibodies. Comparing the anti-Ro52 Ab-positive and anti-Ro52 Ab-negative groups, the frequencies of anti-ARS Ab positivity (63.6% vs. 0%), interstitial lung disease (95.5% vs. 44.4%), glucocorticoid-resistant cardiomyopathy (27.3% vs. 0%), concomitant use of immunosuppressants (95.5% vs. 55.6%), and levels of C-reactive protein were significantly higher in the anti-Ro52 Ab-positive group (P < .05).

Conclusions: Anti-Ro52 Abs were frequently positive in PM/DM, and may be useful as a severity marker.