胸部成熟囊性畸胎瘤的特征性影像表现

Imaging features of thoracic mature cystic teratoma

目的分析胸部成熟囊性畸胎瘤的常见特征性影像表现及诊断思路。方法 1例体检发现左侧胸腔肿物的34岁女性病人行胸部CT及MRI检查,经外科手术切除病变后,病理诊断为成熟囊性畸胎瘤。回顾性分析病人的临床资料、影像表现并复习相关文献。结果 CT平扫及增强检查显示,左侧胸腔巨大囊性病变、密度不均,可见钙化、脂肪密度影,囊内布满多发类圆形低密度小球样影且可移动,增强后部分囊壁轻度强化。MRI显示纵隔巨大肿物突入左侧胸腔,其内信号混杂不均,于主肺动脉分叉水平见椭圆形脂肪信号,病变内布满多发小球样影于T_1WI呈稍低信号、T_2WI呈稍高信号,于反相位T_1WI信号减低、T_1WI抑脂像上信号略减低。左下叶压迫性肺不张,左侧胸腔积液。结论胸部成熟囊性畸胎瘤绝大多数位于前纵隔,其病理来源常以外胚层成熟组织为主,因此瘤体内脂肪具有诊断特异性。"浮球征"是本病的一个少见影像征象。

Objective To analyze the common imaging features and diagnostic strategy of thoracic mature cystic teratoma. Methods A 34 years old female patient with left thoracic tumor was revealed through routine checkup, and then underwent CT and MR examinations. The case was confirmed as mature cystic teratoma by postoperative pathology. The clinical data, imaging performance, and the related literatures were reviewed retrospectively. Results The plain and enhanced CT scan showed a huge cystic occupying lesion in left thorax. The lesion showed heterogeneous density with fat and calcification, which was full of multiple low density floating globules. The cyst wall showed slightly enhancement. While MR showed that the neoplasm was from anterior mediastinum with mixed signals, such as fat signal was found at the level of the main pulmonary artery bifurcation. The floating globules were slightly hypointense on T1 WI and slightly hyperintense on T2 WI, and the signal reduced on the opposed-phase and fat suppressed T1 sequence. Left pleural effusion and left lower lobe compression atelectasis were also found. Conclusion The mature cystic teratoma mostly occurrs in the anterior mediastinum, which mainly contains ectomorphic mature tissues. Fat is a specific marker in the diagnosis for the disease. ＂Floating ball＂ sign is an uncommon feature of mature cystic teratoma.