不典型胸腺瘤和胸腺癌的临床与CT表现比较

目的 探讨不典型胸腺瘤(B3型胸腺瘤)和胸腺癌(C型胸腺瘤)在临床和CT表现上的异同.方法 搜集经手术切除、按2004年WHO胸腺上皮肿瘤分类标准分类,并有完整CT资料的B3型(30例)和C型(17例)胸腺上皮肿瘤,对其包括预后在内的临床资料和CT图像做回顾性分析.2组患者年龄和肿瘤横断面最长径的比较采用独立样本t检验；对于性别、有无重症肌无力、手术方法及2组间肿瘤边缘、形态、有无坏死和钙化、肿瘤的强化形式和程度以及对周围纵隔脂肪、胸壁、大血管、纵隔胸膜、心包和胸壁的侵犯情况,是否存在纵隔淋巴结肿大、胸膜种植转移、胸水和远处转移等采用Fisher精确概率法检验.对于2组患者预后情况则采用Kaplan-Meier法进行生存分析.结果 (1)临床:B3型患者[平均年龄(43±15)岁]较C型[(56±11)岁]年轻(t=-2.905,P=0.006)；90.0％ (27/30) B3型合并有重症肌无力症状,而C型仅5.9％( 1/17),差异有统计学意义(P=0.000)；B3型肿瘤的完整切除率(80.0％,24/30)高于C型(11.8％,2/17,P=0.001)；70.6％( 12/17)C型患者于术后2年内死亡,B3型中仅20.0％ (5/30)在术后2～9年内死亡；5年生存率C型为14.7％,B3型为94.7％,差异有统计学意义(P =0.000).(2)CT表现:C型肿块的长径为(6.4±2.1) cm,大于B3型的(4.6±2.3)cm(t=-2.778,P=0.008)；C型边缘多为不规则形状( 13/17,76.5％),而B3型则多为分叶状(18/30,60.0％,P=0.019)；C型(15/17例,88.2％)较B3型(17/30,56.7％)更容易发生肿瘤坏死(P =0.049)；在增强扫描中与B3型比较,92.8％ (13/14)C型表现为不均匀强化(P=0.042)；同时C型更易发生大血管侵犯(15/17,P=0.001)和远处转移(8/17,P=0.028).结论 B3型和C型胸腺瘤在临床、预后及CT表现有一定差异,有助于作出区别.

Comparison of clinical features and CT findings between atypical thymoma and thymic carcinoma

Objective To investigate the differences and the similarities of clinical presentations and CT features between type B3 thymoma ( atypical thymoma) and type C thymoma ( thymic carcinoma) in the WHO classification of thymic epithelial tumors.Methods Complete CT findings of thirty cases of type B3 and seventeen cases of type C thymic epithelial tumors confirmed by histopathology according to WHO 2004 Classification System and clinical features including the prognosis of each case were reviewed retrospectively.Statistical analyses of the data for the age and the long diameter were performed with Independent-Samples t test between the two groups.Statistical analysis for gender,association with myasthenia gravis,method of the operation,contours,shapes,calcification,necrosis,enhancement pattern of the tumors on CT,presence of mediastinal lymphadenopathy,invasion of mediastinal fat,chest wall,pericardium,great vessel,pleural mediastinum,metastasis to the plural,pleural effusion,distant metastasis were performed with Fisher exact test.Kaplan-Meier method was employed for survival analysis.Results Clinical data:the average age of type B3 group was significantly younger ( t = - 2.905,P = 0.006).90.0％(27/30) of patients in type B3 group were complicated by myasthenia gravis,while only 5.9％ (1/17) of patients in type C group were complicated by myasthenia gravis.The difference between the two groups was statistically significant ( P = 0.000 ).The ratio of complete resection of type B3 group ( 80.0％ ) was significantly higher than that in type C group ( P = 0.001 ),70.6％ (12/17) of patients in type C group died within 2 years after surgical resection,while only 20.0％ (6/30) of patients in type B3 group died within one to nine years after surgical resection.Three years'survival ratio of C group was 29.4％,and five years'survival ratio of C group was lower than 14.7％,which was significantly lower than B3 group( five years'survival ratio was 94.7％ ),which was statistically significant (P =0.000).CT features:the average long diameter of tumor in type C group was ( 6.4 ± 2.1 ) cm,significantly longer than that in type B3 group,which was (4.6 ± 2.3) cm (t = - 2.778,P = 0.008 ),and the contour of tumor in type C group usually showed irregularity ( 13/17,76.5％ ),while it usually showed lobulated ( 18/30,60.0％ ) in type B3 group (P = 0.019 ),more necrosis found in C group ( 15/17,88.2％ ) than B3 group ( 17/30,56.7％ ),compared with type B3 group on enhanced CT,more tumor in type C group showed heterogeneous enhancement (P =0.042),and more great vessel invasion ( 15/17,88.2％,P =0.001 ) and more distant metastasis (8/17,47.0％,P = 0.028) occurred in type C group.Conclusion Most of type B3 and type C thymoma have a certain significant difference in clinical factor,prognosis and CT findings,which are helpful for differentiation.