恶性胸腺瘤的CT与MRI诊断

CT and MRI diagnosis of malignant thymoma

目的 :分析侵袭性胸腺瘤及胸腺癌的CT及MRI表现 ,探讨其鉴别诊断要点。方法 :复习经病理组织学证实的 18例侵袭性胸腺瘤及 9例胸腺癌的CT、MRI所见 ,重点观察肿瘤的大小、密度、边缘改变 ,对周围纵隔结构的侵犯。结果 :18例侵袭性胸腺瘤、9例胸腺癌CT、MRI均表现为前纵隔不规则软组织肿块。前者肿瘤直径大于 8cm者 15例(83 % ) ,病灶内密度及信号不均匀 12例。心血管受侵 16例 ,后者肿块直径在 8cm以上者 7例 (77.8% ) ,肿块内密度及信号不均 6例 ,心血管受累 8例 ,纵隔肺门淋巴结转移 1例 ,肺内转移 3例 ,双侧肾上腺及肝脏转移 1例。结论 :虽然侵袭性胸腺瘤和胸腺癌的影像学表现相似 ,但胸腺癌更具有侵袭性 ,胸外转移常见 。

Objective:To study the CT and MRI findings of invasive thymoma and thymic carcinoma,and to investigate their features to make a differential diagnosis.Methods:CT and MR findings of 18 patients with invasive thymoma and 9 patients with thymic carcinoma confirmed by pathology were reviewed.The size,density and margin of the tumor as well as the invasion of surrounding mediastinum were mainly observed.Results:Of 18 invasive thymoma and 9 thymic carcinomas,CT scans and MRI demonstrated irregular soft tissue mass in anterior mediastinum.The former with greater than 8 cm in diameter was observed in 15 patients(83%),heterogeneous density in 12,cardiovascular invasion in 16.The latter with more than 8 cm in diameter was seen in 7 patients(77.8%), heterogeneous density in 6,cardiovascular invasion in 8.Metastases of thymic carcinoma were found as follows:to the lymph nodes of the mediastinum and hilum(n=1),to the lungs (n=3),to both adrenal glands and liver(n=1).Conclusion:CT and MRI findings of invasive thynoma are similar to those of thymic carcinoma,however,thymic carcinoma is more invasive and more frequent to cause extrathoracic metastases than invasive thymoma.Histologic findings may help to differentiate invasive thymoma from thymic carcinoma.