A Rare Case of Pembrolizumab Induced Pericardial Tamponade in a 77-Year-Old.

We report a rare case of pericardial tamponade in a 77-year-old male with metastatic squamous cell carcinoma (SCC) of the head and neck receiving pembrolizumab. Despite pembrolizumab revolutionizing cancer treatment, it can engender a spectrum of immune-related adverse events. Our patient presented with acute dyspnea and chest pain two weeks post pembrolizumab infusion and was diagnosed with pericardial tamponade requiring an emergent pericardial window. Our case highlights the importance of recognizing and managing this life threatening cardiac event that occurs in up to 0.4% of patients on pembrolizumab or other immune checkpoint inhibitors (ICI).