中枢神经系统（CNS）胚胎瘤是一组异质性、高度侵袭性的肿瘤，常见于儿童，但也可见于青少年和成年人。2021年，CNS世界卫生组织（WHO）分类对其他CNS胚胎瘤的诊断进行了重大改变，包括新的组织-分子肿瘤类型。本文报告了一例儿童病例，属于CNS胚胎瘤的另一种新肿瘤类型“带有BRD4-LEUTX融合的CNS胚胎瘤”。患者为一名4岁女孩，无病史。几周来，她头痛、呕吐、发热，并伴有乏力、体重减轻等全身状况恶化。MRI头部检查显示左顶叶有一个直径很大、部分有包膜的肿块，对侧脑室积水和中线移位。镜下检查显示高细胞密度的肿瘤，由少量胞浆和高染色质核组成的神经外胚层特点的小细胞组成，伴有小的“髓母细胞瘤样”细胞，特征为合胞体排列和局部流动模式。肿瘤细胞普遍阳性表达Synaptophysin, CD56, INI1和SMARCA4，并阴性表达GFAP, OLIG-2, EMA, BCOR, LIN28A和MIC-2。额外的IHC特征包括p53蛋白在超过10％的肿瘤细胞中表达，非常有趣的是，H3K27me3表达丧失。海德堡DNA甲基化分类器将本例分类为“带有BRD4：LEUTX融合的CNS胚胎瘤”。RNA测序分析证实了BRD4（外显子13）-LEUTX（外显子2）融合，DNA测序未找到其他分子变化。我们的病例报告证实了一组新的CNS胚胎瘤亚组，具有高侵袭性潜力，H3K27me3蛋白丧失，BRDA4-LEUTX融合，并名为“带有BRD4-LEUTX融合的胚胎性CNS肿瘤”，应该被纳入新的CNS WHO分类。©2023年作者（S）。

Central Nervous System (CNS) embryonal tumors represent a heterogeneous group of highly aggressive tumors occurring preferentially in children but also described in adolescents and adults. In 2021, the CNS World Health Organization (WHO) classification drastically changed the diagnosis of the other CNS embryonal tumors including new histo-molecular tumor types. Here, we report a pediatric case of a novel tumor type among the other CNS embryonal tumors classified within the methylation class "CNS Embryonal Tumor with BRD4-LEUTX Fusion". The patient was a 4-year girl with no previous history of disease. For a few weeks, she suffered from headaches, vomiting and mild fever associated with increasing asthenia and loss of weight leading to a global deterioration of health. MRI brain examination revealed a large, grossly well-circumscribed tumoral mass lesion located in the left parietal lobe, contralateral hydrocephalus and midline shift. Microscopic examination showed a highly cellular tumor with a polymorphic aspect. The majority of the tumor harbored neuroectodermal features composed of small cells with scant cytoplasm and hyperchromatic nuclei associated with small "medulloblastoma-like" cells characterized by syncytial arrangement and focally a streaming pattern. Tumor cells were diffusely positive for Synaptophysin, CD56, INI1 and SMARCA4 associated with negativity for GFAP, OLIG-2, EMA, BCOR, LIN28A and MIC-2. Additional IHC features included p53 protein expression in more than 10% of the tumor's cells and very interestingly, loss of H3K27me3 expression. The Heidelberg DNA-methylation classifier classified this case as "CNS Embryonal Tumor with BRD4:LEUTX Fusion". RNA-sequencing analyses confirmed the BRD4 (exon 13)-LEUTX (exon 2) fusion with no other molecular alterations found by DNA sequencing. Our case report confirmed that a new subgroup of CNS embryonal tumor with high aggressive potential, loss of H3K27me3 protein expression, BRDA4-LEUTX fusion, named "Embryonal CNS tumor with BRD4-LEUTX fusion", has to be considered into the new CNS WHO classification.© 2023. The Author(s).