Late-onset Pleural and Pericardial Effusion as Immune-related Adverse Events after 94 Cycles of Nivolumab

A 67-year-old man with primary lung adenocarcinoma was hospitalized due to massive bilateral pleural effusion and pericardial effusion after 94 cycles of nivolumab therapy. We were unable to identify the cause of these effusions using blood tests, cytology tests, or bacterial culture of pleural effusion and thoracoscopy. Finally, we administrated corticosteroids, which immediately improved the fluid accumulation. This case may support the introduction of corticosteroids for late-onset pleural and pericardial effusion during immune checkpoint inhibitor (ICI) treatment. However, the safety of rechallenge of ICIs after the improvement of fluid accumulation is controversial.