[A Case of Lung Cancer Discovered Due to Unresponsive Course of Corticosteroids for Rheumatoid-Associated Interstitial Lung Disease].

A 76-year-old female was followed up for rheumatoid arthritis-associated interstitial lung disease(RA-ILD). Consolidation and ground-glass opacities were observed in the right lung. When the corticosteroid was restarted due to a relapse of RA-ILD, most of the shadows disappeared. However, ground-glass nodules remained in the apex of the right lung. Thoracoscopic segmentectomy was performed, and lung cancer was diagnosed. Patients with rheumatoid arthritis suffer from complications such as RA-ILD, drug-induced pneumonia, pulmonary infections, and malignancies. A careful assessment of treatment response should be made in case of a differential diagnosis.