[A Case of Pericardial Effusion Due to Pericardial Metastasis of Breast Cancer Treated with Thoracoscopic Pericardial Window Surgery].

The patient is a woman in her 70s. Seven years after surgery for right breast cancer, she developed a recurrence in the mediastinal lymph nodes and started chemotherapy. However, the treatment was discontinued due to trastuzumab-induced cardiac dysfunction. During follow-up, cardiac function improved, but pericardial effusion was observed. Pericardiocentesis diagnosed pericardial metastasis of breast cancer. Approximately 1 month after the initial pericardiocentesis, reaccumulation of pericardial effusion was observed, necessitating a second procedure. However, the effusion recurred again within a short period. Due to the short time reaccumulation of pericardial effusion, surgical intervention or adhesion therapy was deemed necessary for the prevention of recurrence. Given the risk of further cardiac dysfunction from constrictive pericarditis associated with adhesion therapy, a thoracoscopic pericardial window procedure was selected. Postoperatively, no recurrence of pericardial or pleural effusion has been observed. We report a case of pericardial metastasis from breast cancer successfully managed with thoracoscopic pericardial window creation, achieving good control for over 1 year.