Severe Hemodynamic Instability in a Young Pregnant Woman with Massive Pericardial Effusion and Pulmonary Embolism Secondary to Primary Mediastinal Non-Hodgkin’s Lymphoma

<b>Background:</b> Lymphomas account for approximately 10% of cancers diagnosed during pregnancy, with Hodgkin's lymphoma being the most common. However, non-Hodgkin lymphomas, including primary mediastinal large B-cell lymphoma (PMBCL), also represent a significant proportion. Both mediastinal lymphomas and pregnancy develop a hypercoagulable state, increasing the risk of venous thromboembolism and massive pulmonary embolism (PE), requiring extracorporeal membrane oxygenation (ECMO). <b>Methods:</b> Clinical data, blood test and imagings have been collected by the medical records of the patient. <b>Results:</b> We present a 25-year-old woman, at 32 weeks of gestation, who presented to the emergency department with progressive dyspnea and asthenia. Echocardiography revealed a hemodynamically significant pericardial effusion and severe right ventricular dysfunction. Given the severity of her condition, she underwent an emergency caesarean section and subsequently a pericardial drainage. A chest computed tomography scan revealed an incidental mediastinal mass along with a massive PE. Despite pericardial drainage, she remained hemodynamically unstable. Since thrombolysis was contraindicated for the recent cesarean section, venoarterial ECMO was initiated. Systemic anticoagulation was guaranteed by heparin, which shifted to argatroban for heparin resistance. The mediastinal mass was also biopsied, and the diagnosis of PMBCL carried out. Cytoreductive chemotherapy was initiated with the COMP-R regimen (i.e., cyclophosphamide, vincristine, methotrexate, prednisone, and rituximab), and the patient progressively improved up to ICU and hospital discharge. <b>Conclusions:</b> This case highlights the challenges in managing a complicated patient requiring early multidisciplinary intervention, which was crucial for stabilizing the patient and optimizing fetal and maternal prognosis.