Idiopathic Interstitial Lung Disease with Positive Anti-Zo and Anti-Ro52/SSA1 Antibodies.

A 70-year-old male presented with infiltration, ground-glass opacities, and bronchiectasis on chest radiography, which indicated interstitial pneumonia. Clinical findings (thickening of the skin on the fingers, slight nail fold petechiae, and skin lesions resembling mechanic's hands) suggested early systemic sclerosis and/or polymyositis/dermatomyositis. However, anti-Scl-70, anti-centromere, and anti-aminoacyl tRNA synthetase (anti-ARS) antibodies were negative. Exertion-related oxygenation gradually worsened. Since the multiplex protein array confirmed anti-Zo and anti-Ro52/SSA1 antibody positivity, anti-ARS antibody syndrome was diagnosed and treated with steroids and immunosuppressive drugs. The patient was concurrently diagnosed with advanced colorectal cancer. Treating interstitial pneumonia first allowed for the subsequent treatment of colorectal cancer without worsening the condition.