外周型原始神经外胚层肿瘤的CT和MRI影像特征

背景与目的:外周型原始神经外胚层肿瘤(primitive neuroectodermal tumor,PNET)用组织学方法检查难以与其它的小圆形细胞肿瘤(如尤文氏肉瘤)区别.本研究目的在于分析和探讨外周型PNET的CT和MRI影像特征.方法:回顾性分析7例经病理证实的外周型PNET的CT和MRI表现.结果:7例PNET发病部位分别为左鼻翼、右下颌骨、左/右胸壁、左精索、胸椎旁及腰段椎管内.发生于软组织的PNET CT表现主要为边界不清的软组织肿块,密度不均匀伴坏死、囊变,无钙化,增强后明显不均匀强化.发生于骨的PNET CT表现为溶骨性骨质破坏并伴巨大软组织肿块形成.发生于椎旁或椎管内的PNET MRI表现为与脊髓和马尾分界清的软组织肿块,在T1WI上呈稍低或等信号改变,在T2WI上呈稍高或等信号改变.结论:外周型PNET的CT和MRI表现缺乏特异性影像特征;CT和MRI检查可显示肿瘤的范围和发现远处转移,对确定手术的可切除性及评价治疗效果有重要参考价值.

CT and MRI features of peripheral primitive neuroectodermal tumor

BACKGROUND & OBJECTIVE: It's difficult to distinguish peripheral primitive neuroectodermal tumor (PNET) from other small round cell tumors such as Ewing's sarcoma by histological examination. This study was to analyze the CT and MRI features of peripheral PNET. METHODS: The CT and MRI records of 7 patients with pathologically proved peripheral PNET were reviewed. RESULTS: The tumors were located in the left ala nasi, right lower jaw bone, left chest wall, right chest wall, left spermatic cord, paraspinal, and lumbar vertebral canal. The tumors in soft tissue showed resembled non-calcified, ill-defined soft tissue masses with cystic or necrotic areas on CT images, with heterogeneous enhancement on contrast images. The tumors in the bone showed lytic lesions with large soft tissue masses on CT images. The tumors in the paraspinal and vertebral canal showed well-defined soft tissue masses without involving cord and cauda equine on MRI, and showed isointensity or hypointensity on T1WI and isointensity or hyperintensity on T2WI. CONCLUSIONS: The imaging features of peripheral PNET are non-specific. CT and MRI are useful in delineating the extent, finding distant metastasis, predicting respectability and monitoring treatment of peripheral PNET.