Abstract
A 33-year-old woman at 37 weeks of gestation presented with progressive dyspnea and cough, initially misdiagnosed as pneumonia. Imaging revealed a large (>15 cm) anterior mediastinal mass compressing the pulmonary arteries and bronchi, along with a significant pericardial effusion. Echocardiography confirmed tamponade physiology. Given the high risk of cardiovascular collapse during labor, a multidisciplinary team, including obstetrics, cardiology, anesthesia, and cardiothoracic surgery, proceeded with emergent cesarean delivery under general anesthesia, followed by subxiphoid pericardial window and excisional biopsy. Postoperative recovery occurred in the intensive care unit, and both the mother and infant remained stable. Pathology confirmed primary mediastinal high-grade B-cell lymphoma, and the patient was promptly started on systemic chemotherapy with DA-REPOCH (dose-adjusted etoposide, prednisone, vincristine (Oncovin), cyclophosphamide, doxorubicin (hydroxydaunorubicin), and rituximab). This case underscores the importance of early recognition, rapid multidisciplinary coordination, and integrated oncologic planning in the management of life-threatening cardiothoracic pathology during pregnancy.