Progressive pleural effusion as an immune-related adverse event in non-small cell lung cancer: A case report

Abstract Immune checkpoint inhibitors (ICIs) have improved the clinical outcome of non-small cell lung cancer (NSCLC). However, immune-related adverse events (irAEs) such as pneumonitis, thyroiditis, and colitis have been reported with the increasing use of ICIs. The diagnosis of irAEs relies on exclusion. With proper management, most patients may still benefit from ICI treatment. Pleural effusion is a rare presentation of an irAE. Here, we report a patient who experienced progressive bilateral pleural effusions during first-line treatment of cisplatin, pemetrexed and pembrolizumab. Serial study and surgical pleural biopsy showed the possible etiology of irAE. His pleural effusion subsided after discontinuing therapy. irAE may present as pleural effusion and physicians should be alert to unknown causes of pleural effusion in patients under ICIs treatment.