Aggressive primary mediastinal synovial sarcoma resulting in catastrophic airway compromise and fatal hemoptysis.

Primary mediastinal synovial sarcoma is a rare and aggressive malignancy that may present with nonspecific cardiopulmonary symptoms and be occult on chest radiography. A 45-year-old woman presented with progressive cough, fatigue, and chest discomfort despite an initially unremarkable chest radiograph. Six weeks later, worsening dyspnea, orthopnea, and dysphagia prompted repeat imaging. Chest radiography demonstrated tracheal deviation, and computed tomography angiography revealed an 11.3 cm infiltrative mediastinal mass compressing the central airways, pulmonary vasculature, and left atrium, with an associated pericardial effusion. Endobronchial ultrasound-guided biopsy confirmed biphasic synovial sarcoma with an SS18 rearrangement. The patient subsequently developed cardiac tamponade requiring a pericardial window. The tumor was unresectable because of extensive cardiopulmonary involvement. Despite silicone Y-stent placement and planned chemotherapy, she developed airway obstruction, massive hemoptysis, and fatal respiratory failure. This case demonstrates the rapid progression and life-threatening mechanical complications of primary mediastinal synovial sarcoma. Persistent or progressive cardiopulmonary symptoms should prompt cross-sectional imaging when initial chest radiography is unrevealing.