Objective:To analyse the MSCT features and enhance the knowledge of retroperitoneal peripheral primitive neu-roectodermal tumors(pPNETs). Methods:7 patients' MSCT data of retroperitoneal pPNETs were reviewed which were proved by surgery and pathology. Results:All 7 cases were single tumor and located in the perirenal space. The tumors' diameters were 6.3~15.7 cm,the mean 9.7 cm. 4 tumors were irregular,3 oval and with unclear boundary. On rountine CT,most tumors showed asymmetrical low density;all tumors showed necrosis,cyst degeneration and no calcification,5 solid-cystic change and 4 haemorrhage. On enhanced CT,7 tumors showed slight to moderate asymmetrical continuous enhancement,the solid part of tu-mors showed enhancement as speckle,nodule or strip. 3 tumors showed tumor angiogenesis. The margin of 6 tumors showed half-baked envelope with small burrs in outsides. 7 tumors showed the invasion to organs,vessels or soft tissue. 3 cases were seen with renal hypofunction,3 with metastasis of lymph nodes in renal hilus,2 with metastasis of pelvic. There were no obvi-ous ascites in all 7 cases. Conclusions:The MSCT manifestations of retroperitoneal pPNETs have no characteristics. MSCT can show the intra-tumor structures and the extent of the tumor very well,which is helpful in differentiating diagnosis.%目的:探讨腹膜后外周型原始神经外胚层肿瘤(pPNETs)的MSCT特征,提高对该病的认识.方法:回顾性分析7例经手术病理证实的腹膜后pPNETs的MSCT资料.结果:7例均为单发,且均位于肾脏周围间隙;直径6.3~15.7cm,平均9.7cm;4例形态不规则,3例呈类圆形,境界多不清楚.CT平扫多为略低密度,病灶内部密度不均匀;均出现不同程度的坏死、囊变,5例肾旁病灶坏死、囊变显著,呈囊实性肿块;4例伴出血;均未见钙化.增强扫描多表现为轻中度进行性不均匀持续强化,病灶强化方式多样,实质部分呈片状、结节状及网条状强化,3例内见肿瘤血管;6例肿块边缘见类包膜样改变,但包膜多不完整,外缘可见小毛刺样改变.7例肿瘤均不同程度推挤或侵犯邻近脏器、大血管,并向邻近脂肪间隙浸润,形成强化条索影;3例患侧肾脏实质灌注下降,3例伴肾门淋巴结转移,2例伴骨盆转移;7例均未见明显腹腔积液.结论:腹膜后pPNETs的MSCT表现虽缺乏特征性,但能较好地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.
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