Primary pulmonary monophasic synovial sarcoma initially presenting with bloody pleural effusion: A case report and literature review.

Key Clinical Message: Primary pulmonary synovial sarcoma (PPSS) can originate from blood vessels of the bronchial wall, lung interstitium, and interstitial components, and accounts for 0.1%-0.5% of all primary lung malignancies, the most common symptoms are chest pain, cough, dyspnea, and hemoptysis. Abstract: Synovial sarcoma (SS) is a rare malignant tumor of stromal origin, which accounts for approximately 8%-10% of all soft tissue sarcomas. Primary pulmonary synovial sarcoma (PPSS) can originate from blood vessels of the bronchial wall, lung interstitium, and interstitial components, and accounts for 0.1%-0.5% of all primary lung malignancies. Patient concerns: We report the first case of a 57-year-old man with bloody pleural effusion as an initial manifestation of PPSS in the middle lobe of the right lung diagnosed after surgery. Diagnosis: Chest computed tomography (CT) revealed a mass in the middle lobe of the right lung, which was pathologically diagnosed as a monophasic SS after surgical resection. Interventions: Ten days after preoperative closed chest drainage, a right thoracotomy was performed to remove the right middle lobe of the lung. Outcomes: The patient recovered smoothly and was discharged from the hospital without any other postoperative treatment. A follow-up chest CT scan 7 months postoperatively revealed intrapulmonary recurrence with multiple metastases. Lessons: Monophasic PPSS of the lung may present with bloody pleural effusion as its first manifestation.