少见纵隔恶性生殖细胞来源肿瘤的CT诊断

CT Diagnosis of Rare Malignant Mediastinal Germ Cell Tumors

目的探讨少见纵隔恶性生殖细胞来源肿瘤的CT影像学特征。方法回顾性分析经病理证实的7例少见纵隔恶性生殖细胞来源肿瘤的CT表现。结果 7例肿块均位于前上纵隔,其中精原细胞瘤3例,卵黄囊瘤2例,胚胎性癌1例,混合性生殖细胞肿瘤(90%卵黄囊瘤,10%胚胎性癌)1例。CT表现为圆形或类圆形肿块,肿块内见不同程度囊变或坏死液化区,未见钙化及脂肪成分,边缘不规则与周围脂肪间隙消失并侵犯邻近组织器官等恶性肿瘤征象。3例精原细胞瘤以实性成分为主,强化较均匀,其中1例β-HCG轻度升高;2例卵黄囊瘤以囊性成分为主,实性成分相对少并呈明显不均匀强化,有延迟渐进性强化的特征,AFP显著升高。1例胚胎性癌实性成分呈轻度强化,囊性坏死区无强化。1例混合性生殖细胞肿瘤实性成分呈中度强化,其影像学表现取决于肿块内所含成分及所占比例有关。结论少见纵隔恶性生殖细胞来源肿瘤CT表现具有一定特征性,结合血清AFP及β-HCG有助于提高对该类疾病诊断的准确性。

Objective To investigate the CT features of the rare malignant mediastinal germ cell tumors. Methods CT features of 7 cases confirmed pathologically as rare malignant germ cell tumors were retrospectively analyzed. Results All 7 cases were located in the anterior superior mediastinum,including 3 cases of seminoma,2 cases of yolk sac tumors,1 case of embryonic cell carcinomas,1 case of mixed germ cell tumors（ 90% yolk sac tumor,10% embryo cell carcinomas）. All of the 7 cases were found as a solitary,oval or rounded mass with different cystic degeneration or liquefaction necrosis areas,without calcification or fat composition. All the tumor borders presented as irregular or lobular with adjacent tissues invaded. 3 cases of seminoma consisted of primarily solid components and presented as homogeneous enhancement,and β-HCG was slightly increased in only 1 case; 2 cases of yolk sac tumors consisted of cystic components primarily and the solid parts presented as heterogeneous and persistent delayed enhancement with sharply high AFP; 1 case of embryonic cell carcinomas showed light enhancement,with non-enhancement in the necrosis area; 1 case of mixed germ cell tumors showed moderate enhancement in the solid parts,The imaging findings depend on the mass composition and proportion. Conclusion Rare malignant mediastinal germ cell tumors were found to be with particular CT characteristics,and combining these features with serum alpha fetoprotein and β-HCG may be beneficial for diagnosis and differential diagnosis.