Pulmonary manifestations of anti-ARS antibody positive interstitial pneumonia – With or without PM/DM

Summary Background Autoantibodies against aminoacyl-tRNA synthetases (ARS) have been found to be highly specific for polymyositis and dermatomyositis (PM/DM) and to correlate strongly with complicating interstitial pneumonia (IP). The aim of the present study was to compare the clinical presentations of anti-ARS antibody-positive IP patients with or without manifestations of PM/DM. Methods We retrospectively examined 36 IP patients with anti-ARS antibodies. Sixteen patients presented with and 20 without the features of PM/DM. They were divided into PM/DM-IP and idiopathic-IP (IIP) groups. Clinical symptoms, findings on physical examination, laboratory data, pulmonary function, computed tomography (CT), and bronchoalveolar lavage fluid (BALF) cell counts were compared. Results Skin findings, myalgia, and elevation of serum creatinine kinase were found in the PM/DM-IP group. Features common to both groups included: volume loss in lower bilateral lobes; ground-glass opacities, reticular shadows and traction bronchiectasis on chest CT; high percentage of lymphocytes (IIP: 44.0% ± 21.0% (mean ± SD), PM/DM-IP: 50.5% ± 23.5%) and low CD4/8 ratios (IIP: 0.36 ± 0.34, PM/DM-IP: 0.44 ± 0.42) in BALF; decreased pulmonary function, including percentage of predicted vital capacity (VC) (IIP: 80.1% ± 15.4%, PM/DM-IP: 73.6% ± 16.4%), residual volume (RV) (IIP: 70.7% ± 21.7%, PM/DM-IP: 71.5% ± 17.1%), total lung capacity (TLC) (IIP: 73.4% ± 13.6%, PM/DM-IP: 71.6% ± 13.0%), and diffusing capacity DLco (IIP: 57.5% ± 26.7%, PM/DM-IP: 46.4% ± 10.3%). Both groups achieved good responses to initial corticosteroid or immunosuppressant therapy. Conclusion Patients with anti-ARS antibody-positive IP have common pulmonary manifestations regardless of the presence of PM/DM.