Primary mucinous sarcoma of the lung (PPMS) is a very rare low-grade malignancy that has histological and molecular features similar to extranodal myxoid chondrosarcoma. In the case reported, the diagnosis was established by bronchoscopic biopsy, with the tissue examined by pathology, immunohistochemistry, and molecular pathology, including fluorescence in situ hybridization (FISH) to detect the EWSR1 gene translocation. The tumor caused obstruction of the left common branch of the pulmonary tree, which was confirmed by bronchoscopy. The patient underwent sleeve resection of the lower lobe of the left lung and lymph node dissection using video-assisted thoracic surgery (VATS) under general anesthesia. After the operation, the patient recovered well, and a follow-up CT scan of the chest after two months showed no signs of recurrence. EWSR1 translocation is known to be a genetic alteration associated with some sarcomas, including this tumor type[1][2].