Primary lung cancer with pulmonary alveolar proteinosis treated with immune checkpoint inhibitor: A case report

Primary lung cancer with pulmonary alveolar proteinosis (PAP) is a rare condition. We present a case of a patient with primary lung cancer with PAP treated with an immune checkpoint inhibitor (ICI). A 62-year-old man was diagnosed with autoimmune PAP 8 years prior to current admission. Lung adenocarcinoma was found in his right lung, and platinum-based chemotherapy was administered, followed by atezolizumab. He experienced disease progression after atezolizumab treatment, whereas ICI-induced pneumonia or exacerbation of PAP did not occur. This indicates that ICI may be safely used in patients with primary lung cancer with PAP.