Abstract
Nivolumab improves overall survival rates of patients with advanced or recurrent non-small-cell lung cancer (NSCLC). Among immune-related adverse events caused by nivolumab, interstitial lung disease (ILD) is a clinically serious and potentially life-threatening toxicity, for which appropriate treatment is needed immediately. However, ILD is sometimes difficult to distinguish from invasive lung adenocarcinoma using only computed tomography (CT) findings. A 71-year-old man was diagnosed with advanced lung adenocarcinoma. The patient developed dyspnoea after eight cycles of nivolumab, when chest CT indicated ILD classified with a cryptogenic organizing pneumonia (COP) pattern. Although immunosuppressive therapies improved the CT findings temporarily, dyspnoea was re-exacerbated 2 months later. The CT findings helped in making the diagnosis of a combination of ILD and invasive lung cancer, confirmed by a transbronchial lung biopsy. In conclusion, nivolumab-related ILD and cancer invasion may concur and aggressive biopsy should be considered if nivolumab-related ILD is refractory to immunosuppressive therapy.