【摘要】 目的 分析外周性原始神经外胚层肿瘤（pPNETs）的MRI表现,以提高对本病的影像学认识。方法回顾性分析经手术病理证实5例pPNETs的MRI表现。患者发病年龄11～65岁,平均21岁,男4例,女1例。5例均行MR平扫,3例行CT平扫,4例行MRI增强扫描。结果1例病灶位于盆腔,2例位于大腿软组织,1例位于纵隔,1例位于腭扁桃体,均表现为较大软组织包块,长径7～11cm。CT平扫肿瘤密度略低于肌肉,MR T₁WI序列肿瘤与肌肉信号相近,T₂WI和STIR序列为不均匀高信号。肿瘤中心见囊变区,5例病变内均未见钙化,所有肿瘤均有不均匀强化。CT与MRI均可显示病变上方三角形的骨膜反应。免疫组化结果:肿瘤均表达CD99,并不同程度地表达上皮细胞膜抗原EMA、神经微丝蛋白NF、突触素Syn、Vimentin、S-100。结论MRI扫描对确诊pPNETs缺乏特异性,本病的确诊需病理及免疫组化结果,但MRI能明确显示肿瘤大小、部位与各相邻组织的关系,也有助于判断手术可切除性。更多还原

【Abstract】 Objective To analyze MRI appearances of primitive neuroectodermal tumors（PNETs） of soft tissue,so that to improve the understanding of this disease.Methods MRI appearances of 5 cases with PNETs confirmed pathologically were retrospectively analysed.There were 4 men and 1 women,age ranged from 11～65 years old,with an average age of 21 years old.5 cases,3 cases and 4 cases underwent plain MR imaging,plain CT and MRI enhanced scans,respectively.Results The lesions localized at the pelvis in one,in soft tissue of extremities in 2,in the mediastium in one and in the palatine tonsil in one.The lesions appeared as soft tissue masses of 7～11 cm in size.The tumors were slightly lower dense compared with that of muscles on CT images,and iso-intensity on T₁WI,hyperintensity on both T₂WI and STIR,cystic degeneration was seen in the centre of the tumors.There were no calcifications in the tumors.The triangular periosteal reaction showed by CT and MRI.All tumor cells shwoed positive results in CD99,and showed various degrees of antigen in epithelium,including EM A,NF,Syn,Vimentin and S-100.Conclusion The PNETs show no characteristic manifestations on MRI,the confirmed diagnosis is depended on the pathological and immunohistochemical results.Howeever,MRI can show the size and position of the tumors and the relationship between the tumors and adjacent organizations,which is helpful in administration of surgery.更多还原