摘要目的:观察非典型畸胎样/横纹肌样肿瘤(AT/RT)的临床病理学特点，分析病理误诊原因，总结诊断策略。方法:病例系列研究。回顾性分析西安市儿童医院病理科2010年1月至2018年12月误诊的5例(误诊组)和同期确诊的8例AT/RT病例(确诊组)，行苏木精-伊红、免疫组织化学染色，观察临床特点、组织学形态及免疫表型。2组率的比较采用Fisher′s精确检验，均数比较采用独立样本 t检验，中位数比较采用Mann－Whitney U检验。 结果:(1)误诊组男4例，女1例；中位年龄24个月；4/5例肿瘤位于幕下，1/5例位于脊髓。组织形态学：3/5例可见横纹肌样细胞，2/5例由胚胎样小细胞构成；免疫组织化学染色：4/5例INI1表达缺失，1/5例BRG1表达缺失，均显示多免疫表型。确诊组男7例，女1例，中位年龄22个月，4/8例位于幕上，4/8例位于幕下；组织学8例均可见横纹肌样细胞，免疫组织化学染色均为INI1表达缺失的病例，均显示多免疫表型。(2)误诊组中横纹肌样细胞占肿瘤的百分比[0.45(0，0.46)]低于确诊组[0.55(0.40，0.85)]，差异有统计学意义( Z＝－2.064， P＝0.039)。 结论:发生部位不定、组织形态多样、免疫组织化学显示多表型且存在罕见的BRG1缺失性病例是AT/RT误诊的原因。对形态学有横纹肌样、上皮样和/或胚胎样小细胞的高级别肿瘤，应将AT/RT列为鉴别诊断，免疫组织化学方案应包含INI1和BRG1。

abstractsObjective:To analyze the clinicopathological characteristics of atypical teratoid/rhabdoid tumors (AT/RT) and the causes of pathological misdiagnosis, and summarize diagnostic strategies.Methods:A case series study was conducted.Specifically, the data of 5 misdiagnosed(misdiagnosed group) and 8 confirmed AT/RT cases(confirmed group) in the Department of Pathology of Xi′an Children′s Hospital from January 2010 to December 2018 were retrospectively analyzed.Hematoxylin-eosin and immunohistochemical staining were performed to analyze clinical features, morphology, and immune phenotypes.Rates were compared between the misdiagnosed and confirmed groups by a Fisher′s exact test.Means were compared using an independent sample t-test.Medians were compared by a Mann-Whitney U test. Results:(1)There were 4 males and 1 female in the misdiagnosed group, with a median age of 24 months.In this group, 4/5 tumors were located in the posterior cranial fossa, and 1/5 tumors were located in the spinal cord.Morphologically, rhabdoid cells were detected in 3/5 cases, and the other 2/5 cases consisted of small embryonal cells.Immunohistochemically, INI1 and BRG1 expressions were absent in 4/5 and 1/5 cases, respectively.All of them showed multiple immunephenotypes.There were 7 males and 1 female in the confirmed group, with a median age of 22 months.In the confirmed group, 4/8 tumors were located in the supratentorial region and 4/8 tumors were located in the infratentorial region.Rhabdoid cells, deficient INI1 expression and multiple immunephenotypes were observed in all 8 cases.(2)The percentage of rhabdoid cells in the misdiagnosed group was significantly lower[0.45(0, 0.46)] than that in the confirmed group[0.55(0.40, 0.85)]( Z=-2.064, P=0.039). Conclusions:The causes of misdiagnosis of AT/RT are variable sites of occurrence, diverse histomorphology, multiple phenotypes in immunohistochemistry and rare BRG1 deficiency.For high-grade rhabdoid, epithelioid, and/or embryonic small cell tumors, AT/RT should be differentiated and immunohistochemistry protocols should include INI1 and BRG1.