Clinical characteristics of dermatomyosits/polymyositis associated interstitial lung disease according to the autoantibody

Background : Dermatomyositis (DM) and polymyositis (PM) often have association with interstitial lung disease (ILD) which have disease specific autoantibody. Methodology :We reviewed medical records of DM/PM associated ILD from January 2000 to December 2017 according to the autoantibody. Result : We identified 52 patients, of whom30 were antibody negative, 18 had anti aminoacyl-tRNA synthetases (ARS) antibodies and 4 had anti melanoma differentiation-associated gene (MDA)-5 antibody. In high resolution computed tomography (HRCT) of the chest, area of ground glass opacity (GGO), consolidation, and lung tip consolidation were more extensive in anti MDA-5 antibody positive patients (p=0.051, p=0.026, and p=0.027, respectively). Among laboratory findings, GOT had strong correlations with CPK (r=0.889, p<0.001), and LDH (r=0.910, p<0.001). Among roentgenographic findings, there were moderate correlations between GGO and consolidation (r=0.668, p<0.001), and between reticular shadow and traction bronchiectasis (p=0.633, p<0.001). ILD patients with anti MDA-5 antibodies had decreased survival (1.00 vs 84.3, 22.9 months, p<0.001). Conclusion : ILD patients with anti ARS antibody had intense inflammation, but reversible fibrosis and good prognosis. On the other hand, anti MDA-5 antibody positive ILD patients had shorter survival. Extent of parenchymal shadow and serum GOT were useful indicator of disease activity of PM/DM associated ILD patients in our cohort.