外周性原始神经外胚层肿瘤的CT、MRI表现与病理对照分析

CT,MRI and pathological analysis of peripheral primitive neuroectodermal tumors

目的分析外周性原始神经外胚层肿瘤(pPNETs)的CT与MRI表现,以提高对本病的认识。方法回顾性分析经病理证实的19例pPNETs的CT和MRI表现。患者发病年龄7～57岁,中位年龄22岁;男11例、女8例。19例全部行CT检查,其中13例同时行MR检查。结果3例病灶位于颅内,7例位于四肢,2例位于胸部,4例位于腹部,3例位于脊柱。软组织pPNETs的CT表现为大的、边界不清的软组织肿块,密度不均匀伴坏死囊变,不伴钙化,增强后呈不均匀强化。骨pPNETs主要表现为较大的溶骨性骨质破坏伴软组织肿块,有1例可见瘤骨形成,增强后呈不均匀强化。在MRSET1WI上表现为等肌肉信号,T2WI上表现为不均匀高信号,部分病例可见假包膜改变。免疫组织化学结果,肿瘤均表达CD99,并不同程度地表达上皮细胞膜抗原(EMA)、突触素(Syn)、胶质纤维酸性蛋白(GFAP)等,但不表达白细胞共同抗原(LCA)等。结论pPNETs的CT与MRI缺乏特征性表现,但能较好的显示肿瘤的内部结构、明确肿瘤的范围,有助于该病的鉴别诊断、指导制定治疗方案、检出远处转移和评价治疗效果。

Objective To analyze the CT and MRI appearances and to improve the knowledge of peripheral primitive neuroectodermal tumors （pPNETs）. Methods CT or MRI were performed in 19 patients of pPNETs, which were confirmed by pathology. Results All the tumors were with unclear margin. Three cases occurred in intracalvarium, 7 in the extremities, 2 in the chest, 4 in the abdomen, and 3 inside the spine. CT appearance of the tumors arising from soft tissue showed large, ill-defined, noncalcified mass and heterogeneous appearance with hypodense cystic areas. The tumors demonstrated heterogeneous contrast enhancement. The pPNETs arising from bone demonstrated extensive lytic lesion with large soft tissue mass, one case with newly-born bone and demonstrated heterogeneous contrast enhancement. The tumors demonstrated homogeneous intensity as muscle on SE T1WI and heterogeneous hyperintense signal on T2WI. Irmnunohistochemically, tumor cells showed positive for CD99, Syn, GFAP and negative for LCA. 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 differentiating diagnosis, predicting resectability, detecting distant metastases and evaluating the response to treatment.