摘要目的:探讨白血病病毒整合基因1 (FLI1)、NKX2.2在儿童骨外尤文肉瘤病理诊断及与其他小圆细胞肿瘤鉴别诊断中的价值。方法:回顾性分析西安市儿童医院和空军军医大学西京医院病理科2014年1月至2020年12月诊断的儿童骨外尤文肉瘤及其他小圆细胞肿瘤病例资料，采用免疫组织化学染色法观察FLI1、NKX2.2的表达情况。结果:1．骨外尤文肉瘤27例；其他小圆细胞肿瘤145例，包括分化差型及未分化型神经母细胞瘤40例，横纹肌肉瘤34例，胚芽为主型肾母细胞瘤30例，淋巴瘤25例，恶性横纹肌样瘤10例，髓系肉瘤2例，促纤维增生性小圆细胞肿瘤1例，BCOR重排肉瘤1例，CIC重排肉瘤1例，婴儿黑色素性神经外胚瘤1例。2.FLI1在骨外尤文肉瘤中的敏感性为88.9%(24/27例)，特异性为5.5%(8/145例)，阳性预测值为14.9%(24/161例)，阴性预测值为72.8%(8/11例)；NKX2.2在骨外尤文肉瘤中的敏感性为92.6%(25/27例)，特异性为97.9%(142/145例)，阳性预测值为89.3%(25/28例)，阴性预测值为98.6%(142/144例)；FLI1和NKX2.2联合检测的敏感性为85.2%，特异性为97.9%，阳性预测值为88.5%，阴性预测值为97.3%。结论:NKX2.2在儿童骨外尤文肉瘤中有较高的敏感性和特异性，可作为一线抗体用于其诊断和鉴别诊断；FLI1敏感性高，但特异性差，可作为一线抗体用于诊断，但在鉴别诊断时应联合其他抗体以及分子检测，以免误诊。

abstractsObjective:To investigate the value of friend leukemia integration-1 (FLI1) and NKX2.2 in the diagnosis of pediatric extraskeletal Ewing′s sarcoma (E-EWS), and the differential diagnosis of other pediatric small round cell tumors.Methods:Clinical data of children with E-EWS and other small round cell tumors diagnosed in the Department of Pathology of Xi′an Children′s Hospital and Xijing Hospital, Air Forth Medical University from January 2014 to December 2020 were retrospectively analyzed.Expression levels of FLI1 and NKX2.2 were examined by immunohistochemical staining.Results:(1)A total of 27 cases of E-EWS and 145 cases of other small round cell tumors were included, including 40 cases of poorly differentiated and undifferentiated neuroblastoma, 34 cases of rhabdomyosarcoma, 30 cases of metanephric Wilms tumor, 25 cases of lymphoma, 10 cases of malignant rhabdomyosarcoma, 2 cases of myeloid sarcoma, 1 case of desmoplastic small round cell tumor, 1 case of BCOR-rearranged sarcoma, 1 case of CIC-rearranged sarcoma and 1 case of melanotic neuroectodermal tumor of infancy.(2)The sensitivity, specificity, positive and negative predictive value of FLI1 in E-EWS were 88.9%(24/27 cases), 5.5%(8/145 cases), 14.9%(24/161 cases) and 72.8% (8/11 cases), respectively, and those of NKX2.2 in E-EWS were 92.6%(25/27 cases), 97.9%(142/145 cases), 89.3% (25/28 cases) and 98.6%(142/144 cases), respectively.The sensitivity, specificity, positive and negative predictive value of combined FLI1 and NKX2.2 were 85.2%, 97.9%, 88.5%, and 97.3%, respectively.Conclusions:NKX2.2 is sensitive and specific for the differential diagnosis of E-EWS from other pediatric small round cell tumors, showing a high diagnostic utility.FLI1 has high sensitivity but poor specificity for diagnosing E-EWS.The combination of detecting FLI1, NKX2.2 and other antibodies and genetic analysis is recommended to prevent misdiagnosis.