Nonspecific interstitial pneumonia (NSIP) associated with anti-KS antibody: differentiation from idiopathic NSIP.

We report two cases of biopsy-proven nonspecific interstitial pneumonia (NSIP) with anti-KS (asparaginyl-tRNA) antibody. Anti-KS antibody is the sixth anti-aminoacyl-tRNA synthetase (ARS) antibody. They showed interstitial pneumonia without clinical symptoms, and high resolution computed tomography (HRCT) of the chest demonstrated consolidation along bronchovascular bundles and volume loss in the bilateral lower lobes, which were suggestive of connective tissue diseases (CTD). One case of cellular NSIP responded to corticosteroid, but the other case of fibrotic NSIP required corticosteroid and cyclosporin. In patients with these HRCT findings, the measurement of anti-ARS antibodies could be helpful even in the absence of clinical symptoms suggestive of CTD.