外周性原始神经外胚层肿瘤的CT表现与病理对照

摘要

目的 研究外周型原始神经外胚层肿瘤(peripheral primitive neuroectodermal tumors,pPNET)的CT影像学表现,并结合病理、免疫组化特征,以期提高对该病的认识及鉴别诊断能力.方法 回顾性分析经病理及免疫组化标记证实的15例pPNET的CT表现.4例行CT平扫检查,其余11例均行CT平扫及增强检查.结果 15例pPNET分别位于胸壁(4例)、腹腔(2例)、腹膜后(2例)、颈部(1例)、肩部(1例)、腹股沟(1例),胫骨近端(1例)、骶髂骨(1例)、脊柱旁(2例),11例软组织pPNET的CT表现为边界不清或清楚的软组织肿块,伴或不伴邻近骨质的溶骨性破坏,形态规则或不规则,密度不均匀,多伴坏死、囊变,1例伴有点状钙化,1例伴有瘤骨,增强后呈中度或明显不均匀强化,(双期扫描中)2例病灶门脉期持续强化；4例骨或椎旁pPNET主要表现为较大的溶骨性骨质破坏伴周围软组织肿块,2例病变由椎间孔延伸至椎管内压迫脊髓,1例可见瘤骨,1例可见骨膜反应,增强后中度以上不均质强化,15例病变中2例伴肝脏转移,2例伴肺转移,1例伴纵隔、腹膜后淋巴结转移.免疫组化标记物中阳性表达前三位的由高到低依次为:Vimentin、CD99、Syn.结论 pPNET的CT影像表现缺乏特异性,CT检查能较好地显示肿瘤的内部结构、血供情况,明确肿瘤的范围、毗邻结构的侵犯情况,判定手术切除的可能性、检出远处转移和评价疗效,最终确诊须结合病理及免疫组化检查.%Objective To study CT findings of peripheral primitive neuroectodermal tumors (peripheral primitive neuro-ectodermal tumors, pPNET) in order to raise awareness and to improve the diagnostic ability of radiologists. Methods The imaging findings on plain (4 cases) and dual phase contrast enhanced (11 cases) CT of 15 cases with pPNET confirmed pathohistologically were reviewed retrospectively. Results Lesions of 15 cases were located in the chest wall (4 cases), abdominal cavity (2 cases), retroperitoneal space (n = 2), neck (n = 1), shoulder (n = 1), inguinal region (1 case), proximal tibia (1 case), sacral iliac bone (1 case ) and paraspinal area (2 cases ). 11 cases of soft tissue pPNET manifested as ill /well defined, regular or irregular, inhomogeneous soft tissue mass, with or without adjacent bone destruction on plain CT and showed moderate to marked inhomogeneous enhancement following contrast administration with continuous enhancement in 2 cases on portal phase. Cystic or necrotic low density area were seen in most cases. Tumor bone were detected in 1 case and punctiform calcification in another one. 4 cases of bone or paraspinal pPNET revealed large osteolytic bone destruction with soft tissue mass, accompanied by spinal cord compression in 2 cases and tumor bone and periosteal reaction in one. In 15 patients, hepatic metastases, lung metastasis, mediastinal and retroperitoneal lymph node metastases were found in 2, 2, 1 cases respectively. The positive rate of immunohistochemical markers, from high to low, were Vimentin, CD99, Syn. Conclusion pPNET has no specific findings on CT, but CT examination can help us to determine the size, internal structure, blood supply and infiltration to adjacent structures of the mass and to assess the possibility of resection, distant metastases and the efficacy of treatment. The final diagnosis should be combined with pathologic and immunohistochemical examinations.