外周型原始神经外胚层肿瘤的影像学表现

目的：探讨发生于多部位的外周型原始神经外胚层肿瘤（pPNETs）的CT及MRI表现，以提高对该病的影像诊断及鉴别诊断水平。方法回顾性分析经病理证实的14例多部位pPNETs的临床及影像资料。其中男10例，女4例。结果发病年龄12～58岁，平均年龄34.29岁。除2例发生于皮肤下软组织病灶较小外，其余病灶都较大，最大平均直径为8 cm，表现为侵袭性软组织肿块，以替代和（或）推移邻近结构方式生长，CT表现为肿块内密度不均，其内未见钙化，骨质破坏区未见骨质硬化、瘤骨形成和骨膜反应，增强后呈不均匀轻至中度强化；MR表现为肿块T1WI与肌肉呈等信号，T2WI呈不均匀高信号，2例在DWI上呈高信号，瘤内多发囊变坏死区及纤细低信号分隔，增强后不均匀明显强化。结论 pPNETs的CT和MRI表现无明显特异性，但CT与MR能较准确描述肿瘤发生部位、内部及周边结构关系及转移情况，对临床治疗和长期随访有重要的指导价值。

Imaging Features of Peripheral Primitive Neuroectodermal Tumors

Objective To study the CT and MRI appearances of peripheral primitive neuroectodermal tumors （pPNETs）. Methods CT and MRI of 14 patients with pPNET located in different region were analyzed retrospec-tively. Ten were male, others were female. Results Age range at diagnosis was 12～58 years （mean 34.29 years） old. In CT and MR ifndings, in addition to the 2 small cases occurring in soft tissue under the skin, the maximum average diameter of the remaining lesions were larger （8 cm）. Invasive large soft tissue mass tended to displace adjacent soft tissue structures rather than invade or encase them. The CT ifndings of pPNETs were soft mass of heterogeneous density without calciifcation and with light to moderate inhomogeneous enhancement, the osteo-lytic destruction without osteosclerosis, periosteum reaction and tumor bone formation. In the MR ifndings, the tumors demonstrated homogeneous intensity as muscles on T1W images and heterogeneous hyperintensity signal on T2W images, 2 cases were hyperintensity on diffusion weighted imaging. In the intratumoral, multiple capsule necrotic areas and slender separated low signal can be shown. The lesions demonstrated heterogeneous obvious contrast enhancement. Conclusion The pPNETs show no characteristic manifestations on CT and MRI. However,CT and MRI can show the intra-tumor structures and the extent of the tumor very well, which is helpful in differ-entiating diagnosis, predicting resectability, detecting distant metastases and evaluating the response to treatment.