目的 探讨外周型原始神经外胚 层肿瘤的CT表现。方法 回顾性分析经病 理证实的12例外周型原始神经外胚层肿 瘤的影像及临床资料。结果 肿瘤位于盆 腔5例(含前列腺2例，卵巢1例)，胸部4例 (胸壁3例，肺部1例)，腹腔、左大腿及骶 髂骨各1例，其中单发10例，多发2例。肿 瘤大小约6.2-22cm，平均值为12cm(肿瘤 最大直径)。CT显示肿瘤多为等低混杂密 度，边界不清。增强扫描病灶呈不均匀性 强化，囊变及坏死区无强化。结论 外周 型原始神经外胚层肿瘤具有恶性肿瘤的一 般特征，儿童或青少年发生于胸部侵袭性 软组织肿块应高度可疑。CT能明确肿瘤大 小、内部结构及周围侵犯、远处转移。外 周型原始神经外胚层肿瘤的确诊主要依据 病理学检查。

Objective To investigate the CT features of peripheral primitive neuroectodermal tumors. Methods The clinical and CT data of 12cases with pPNET confirmed by pathology were retrospectively analyzed. Results The tumors were located in 5 cases of pelvic cavity (including prostate in 2 cases, ovary in 1 cases), chest 4 cases(chest wall in 3 cases, lung in 3 case), abdominal cavity, left thigh and sacral-iliac bone in 1 cases, there were single lesion in 10 cases and multiple lesions in 2 cases. The tumor size was 6.2-22cm,with the average value of 12cm. CT showed that most of the lesions were mixed with hypodense and iso or hypodense, and the boundary of lesions was not clear. Inhomogeneous enhancement from slight to moderate was showed in the lesions on contrast CT scan, and there was no enhancement of cystic degeneration and necrosis. Conclusion CT features of PNET have the general characteristics of malignant tumors, the pPNET should be highly suspicious on chest wall aggressive soft tissue tumor especially in children and adolescents. The CT imege can be used to show the size, internal structure of tumor, help to define their scope and distant metastasis. The pPNET final diagnosis depends on histopathological examination.