A pulmonary mass extending into the left atrium through the pulmonary vein: a rare diagnosis with an unusual origin.

INTRODUCTION: Myxofibrosarcoma usually occurs in the extremities of middle-aged to older adults. Metastatic myxofibrosarcomas generally emerge in the lung. In this case report, we aim to present a case of primary pulmonary myxofibrosarcoma with tumor thrombus extending into the left atrium without pulmonary vein or atrial invasion. CASE PRESENTATION: A 55-year-old male who was being followed up due to a pulmonary nodule presented with a mass extending from the left lower lobe to the left atrium. No extrathoracic malignancy was detected in the pre-operative examination. The mass extending into the left atrium without invasion was excised with the lower lobe of the left lung. A post-operative histopathological examination revealed myxofibrosarcoma. CONCLUSION: Very few cases of cervical, thoracic wall, mediastinum and cardiac primary myxofibrosarcoma have been documented, and to the best of our knowledge, only one primary pulmonary myxofibrosarcoma case has previously been reported in the English literature. Here, we present a case of primary pulmonary myxofibrosarcoma that extended to the left atrium through the pulmonary vein. In such rare clinical presentations, intracardiac tumor resection should precede pulmonary resection due to the possibility of catastrophic tumor embolisms.