儿童骨肌原始神经外胚层肿瘤的CT和MRI表现

CT and MRI analysis of peripheral primitive neuroetodermal tumors of bones and soft tissue in children

目的：探讨儿童骨肌来源外周性原始神经外胚层肿瘤（pPNETs）的CT和MRI影像学特点。方法：回顾性分析经我院病理证实的14例骨肌来源pPNETs患儿的CT及MRI影像学表现。其中男8例,女6例;年龄21个月～13岁,中位年龄9岁。10例行CT扫描,其中5例行CT增强扫描;6例行MRI检查,其中5例同时行MRI增强扫描。结果：本组14例中骨来源和软组织来源各7例,位于胸壁4例、肩胛骨、下肢、脊柱旁区和头部各2例、骨盆1例。骨来源pPNETs的CT表现为溶骨性为主的骨质破坏伴有周围软组织肿块,直径3～8cm,边界多模糊不清,增强后呈不均匀强化;主要MRI表现为T1WI上受累骨结构内见稍低信号,T2WI上呈高信号,骨皮质低信号不连续,周围可见囊实性肿块、呈明显不均匀强化。软组织来源的pPNETs CT表现为软组织密度肿块,内部可有低密度坏死区、钙化少见,肿块通常较大,直径5～15cm,增强扫描肿瘤内可见片絮状强化或不均匀轻度强化,邻近骨性结构可受累;主要MRI表现为T1WI上骨质破坏区多呈等信号或稍低信号,T2WI上多呈不均匀等信号及高信号,增强扫描呈不均匀明显强化,其内囊变坏死区无明显强化,周围骨性结构受累时呈略长T1、长T2信号。结论：儿童骨肌来源pPNET的影像学表现特异性不强,但在临床诊断儿童骨骼肌肉来源的恶性肿瘤时需要注意与本病进行鉴别诊断,CT和MRI不仅可以显示肿瘤的范围,同时对肿瘤可切除性的判断以及治疗效果的监测也很有帮助。

Objective：To study the CT and MRI features of peripheral primitive neuroectodermal tumors （pPNETs） of bones and soft tissue in children. Methods：CT or MRI was performed in 14 patients of pPNETs,which were confirmed by pathology. Age range at diagnosis was 21 monthes ～ 13 years （mean 9 years）. 10 cases underwent plan CT scan,inclu ding 5 cases with contrast enhanced CT scan. MRI was performed in 6 cases,including 5 cases with contrast enhanced scan. Results：The tumor occurred in bones or soft tissues in 7 cases each. The location of the tumors included chest wall （n=4）, scapula （n=2）,legs （n= 2）, paraspinal region （n= 2）, head （n= 2）, and pelvis （n= 1）. The main CT findings of the pPNETs in bones were bone destruction with surrounding soft tissue masses, tumor size of 3 ～8cm, ill defined margin,inho mogeneous enhancement on contrast enhanced scan;the main MRI findings were as follows：bone destruction in which there were areas with slightly lower signal than muscle on Tt WI and higher signal on T2 WI, and the lesions were accompanied by cystic and solid masses which showed inhomogeneous enhancement on contrast enhanced scan. The main CT findings of the pPNETs in soft tissue included soft tissue density mass with large size （5～15cm） ,low density in it and inhomogeneous en- hancement, calcification was uncommon, adjacent bones could be involved. The lesions showed iso intensity or slightly lower signal than muscle on TI WI,iso-intensity or hyper-intensity on T～ WI,inhomogeneous enhancement and the adjacent bones showed hypointensity on T～WI and hyperintesity on T2WI. Conclusion： Although the imaging features in young age group with peripheral neuroectodermal tumors are non-specific,they should be taken into account in differential diagnosis of bone and soft tissue tumors with aggressive behavior. CT and MRI are useful in delineating and evaluation of the extent and re- sectability of pPNETs and monitoring the effect of treatment.