AB0684 DO WE DIAGNOSE ALL THE ANTISYNTHETASE SYNDROME?

Abstract

Background: Antisynthetase syndrome (AS) is an autoimmune disease characterized by the presence of antiaminoacyl tRNA-synthetase antibodies (anti-ARS) and clinical manifestations that may include interstitial lung disease (ILD), myositis, non erosive arthritis, Raynaud’s phenomenon (RP), fever and mechanic’s hands. Until the Connors diagnostic criteria appeared in 2010, these patients with anti-ARS antibody were classified as an idiopathic inflammatory myopathy, or if they did not present myositis, they remained undiagnosed. Objectives: To identify patients with anti-ARS antibodies from our hospital since June 2015, when the immunology laboratory was inaugurated, and to verify if they fulfilled the aS criteria. Methods: Retrospective observational study carried out in a regional hospital in Barcelona with a reference population of 260,000 inhabitants. All patients with any anti-ARS antibody (Jo1, PL7, PL12, EJ) positive were selected, determined by the Dot Blot Polymyositis/Scleroderma IgD D-Teck. We applied Connors diagnostic criteria and collected demographic, clinical and instrumental data, and types of antibodies. Results: We identified 18 patients with anti-ARS antibody, 9 anti-Jo1 (53%), 4 anti-PL7, 3 anti PL-12 and 1 anti-EJ. Of these, 13 had values of aNA > 1/80, 3 values of 1/80 and 1 negative. Other antibodies identified were anti-Ro52 in 4, anti-DNA in 4 and anti-Scl70 in 1. All pacients except one met aS criteria. None of anti-DNA positive subjects met criteria for erythematosus systemic lupus or systemic sclerosis. The majority were women (88%) with a mean age at diagnosis of 62 years (27-83 years), 16 Caucasians and 1 asian. The clinical manifestations reported were: 5 myositis (29%), 11 ILD (6 BOOP and 5 NSIP) (65%), 6 arthritis (2 polyarthritis, 2 oligoarthritis, 1 palindromic, 1 shoulder girdle syndrome) (35%), 3 Raynaud’s phenomenon (17.5%), 2 mechanic’s hands (11%) and 6 fever (35%). Only one patient had the classic triad (myositis, arthritis, ILD, Jo1), 2 had myositis with ILD (Jo1), 1 myositis with arthritis (PL12), 1 ILD with arthritis (PL7), 7 ILD (Jo1, PL7, PL12), 3 arthritis (Jo1), 1 RP (Jo1) and 1 fever (EJ). Ten had a nailfold capillaroscopy performed, 7 of them had any alteration: 1 active systemic sclerosis pattern and 6 nonspecific (6 ramified capillaries and 3 microhemorrhages). Conclusion: Our immunologically defined cohort has fewer clinical manifestations than described in clinically defined cohorts (AENAS group and EuroMyositis). Only 30% of patients had myositis and 70% had a single non-myositis clinical manifestation associated with anti-ARS antibody. Actually, it involved de-novo diagnosis of aS in half of them. In patients with suspected aS with low or negative aNA, antibody blot determination is definitive. Nailfold capillaroscopy in undefined cases is a fundamental tool for diagnosing aS. Disclosure of interests: None declared