From Lung to Heart: Unusual Case of Pulmonary Myxoid Sarcoma

A 77-year-old man with multiple comorbidities presented with cough, dyspnea and nonspecific malaise. Chest computed tomography revealed a mass in the right lower lobe of the lung, along with an associated hypodense lesion in the left atrium. Echocardiography showed a mobile mass in the left atrium, initially suspected to be a thrombus. Transesophageal echocardiography and contrast-enhanced computed tomography demonstrated a 7.5 × 4 × 5-cm tumor originating from the right inferior pulmonary vein, extending into the left atrium and ventricle, causing severe mitral stenosis. Lung biopsy confirmed primary pulmonary myxoid sarcoma. This rare case highlights the importance of comprehensive cardiac imaging in differentiating intracardiac masses and the challenges in diagnosing uncommon malignancies with atypical presentations.