Cardiac tamponade in a patient with stage IV lung adenocarcinoma treated with pembrolizumab.

Immunotherapy drugs are associated with a multitude of immune-related adverse events. We describe a case of cardiac tamponade in a patient with stage IV lung adenocarcinoma, with almost 100% expression of PDL-1, treated with pembrolizumab. The patient is a 62-year-old male who developed worsening shortness of breath after five cycles of pembrolizumab. He was diagnosed with large pericardial effusion on computed tomography chest. Echocardiogram confirmed tamponade physiology. He was treated with discontinuation of pembrolizumab and urgent pericardial window followed by high dose prednisone with tapering. The patient responded very well to the treatment. We have comprehensively reviewed cases of pericardial effusion secondary to either immune mediated mechanisms or pseudoprogression.