Abstract
Nivolumab is an immune checkpoint inhibitor that is used to treat various advanced cancers, including metastatic non-small cell lung cancer (NSCLC). Nivolumab treatment has different side effects. For this patient with advanced NSCLC, pericardial effusion was considered to be an immune-related adverse event after immunotherapy. It was characterized by deterioration of symptoms and considered to be pseudo-progression. The pericardial effusion gradually disappeared as nivolumab treatment continued during intensive follow-up monitoring. After chemotherapy and disease progression, the patient was treated with oral targeted therapy based on genes that were detected. After the re-imaging to assess the targeted therapy progress, immunotherapy was used. During immunotherapy, the patient showed increased pericardial effusion, and he underwent one pericardial puncture, in which 200 mL of pericardial effusion was drained. The pericardial effusion after puncture was not diagnosed as malignant by pathology, and the pericardial effusion remained. Shortness of breath continually improved during immunotherapy, and immunotherapy was continued with close observation. After 11 cycles, pericardial effusion had resolved. This case suggested that NSCLC pericardial effusion that was caused by an immune-related adverse event after immunotherapy might be considered to be pseudo-progression.