Cardiac tamponade during pembrolizumab treatment in a patient with ovarian cancer: a case report.

We present the case of a 39-year-old woman with platinum-resistant ovarian cancer who was treated with pembrolizumab. After five cycles of pembrolizumab treatment, she suddenly developed cardiac tamponade with a pleural effusion. The malignant pericardial and pleural effusion had increased, while the other malignant lesions had diminished in size.