目的:了解纵隔巨大恶性滑膜肉瘤的临床特点及CT表现，提高临床医师对该病的诊疗水平。方法:报道2例原发性纵隔巨大恶性滑膜肉瘤的临床资料，并针对本病的CT表现和鉴别诊断进行文献复习。结果:原发性纵隔巨大恶性滑膜肉瘤临床罕见，CT表现为形态不规则的囊实性肿块，伴有壁结节，邻近骨质溶骨性破坏，与邻近组织分界不清，增强表现为肿瘤实性成分和壁结节强化而囊变坏死区无强化的不均匀强化。本文2例分别向锁骨上方“穿孔样”生长和向左胸腔内生长，存在肺转移、淋巴转移。结论:纵隔恶性滑膜肉瘤为少见病，恶性程度高，强调“早发现、早诊断、早治疗”。在纵隔肿瘤的鉴别诊断中应将其考虑在内，但确诊需结合病理和免疫组化结果。临床医师需利用影像学检查评估的优势，对滑膜肉瘤的诊断、转移评估以及手术治疗方案的选择提供辅助指导。“,”Objective:To understand the clinical features and computed tomography (CT) imaging performance of mediastinal giant malignant synovial sarcoma (SS) and to improve the clinicians′ diagnosis and treatment of this disease.Methods:We report the clinical data of 2 cases of primary mediastinal giant malignant SS, and reviews the literature for CT presentation and differential diagnosis.Results:Primary giant malignant SS of mediastinum is rare in clinic. CT showed irregular cystic and solid mass with mural nodules, adjacent osteolytic destruction, unclear boundary with adjacent tissues. The enhancement showed that the solid components of the tumor and mural nodules were enhanced, while the cystic necrosis area had no enhanced uneven enhancement. The two cases in this paper showed “ borehole-like” growth above the clavicle and growth into the left thoracic cavity, with pulmonary metastasis and lymphatic metastasis respectively.Conclusions:Mediastinal malignant SS is a rare disease with high malignancy and easy to metastasize, which emphasizes “ early detection, early diagnosis and early treatment” . It should be taken into account in the differential diagnosis of mediastinal tumors, but the confirmation of diagnosis needs to be combined with pathological and immunohistochemical findings. Clinicians need to take advantage of imaging examinations to provide auxiliary guidance on the diagnosis, metastasis assessment and surgical treatment options of SS.