Concurrence of nivolumab‐induced interstitial lung disease and cancer invasion

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.