The most recurrent fusion of central nervous system high-grade neuroepithelial tumor with MN1 alteration (HGNET-MN1) is MN1 rearrangement. Here, we report the case of a 36-year-old man with spinal cord astroblastoma showing Ewing Sarcoma breakpoint region 1/EWS RNA-binding protein 1 (EWSR1)-BEN domain-containing 2 (BEND2) fusion. The patient presented with back pain, gait disturbance and dysesthesia in the lower extremities and trunk. Magnetic resonance imaging showed an intramedullary tumor at the T3–5 level, displaying homogeneous gadolinium enhancement. Partial tumor removal was performed with laminectomy. Histological examinations demonstrated solid growth of epithelioid tumor cells showing high cellularity, a pseudopapillary structure, intervening hyalinized fibrous stroma, and some mitoses. Astroblastoma was diagnosed, classified as HGNET-MN1 by the German Cancer Research Center methylation classifier. MN1 alteration was not detected by fluorescence in situ hybridization (FISH), but EWSR1-BEND2 fusion was detected by FISH and RNA sequencing. Previously, a child with EWSR1-BEND2 fusion-positive spinal astroblastoma classified as HGNET-MN1 was reported. In conjunction with that, the present case provides evidence that EWSR1-BEND2 fusion is identified in the entity of HGNET-MN1. Taken together, the BEND2 alteration rather than MN1 may determine the biology of a subset of the central nervous system HGNET-MN1 subclass.

中枢神经系统高级别神经上皮肿瘤与MN1改变（HGNET- MN1）最常见的融合是MN1重排。在这里，我们报告了一名患有脊髓星形母细胞瘤的 36 岁男性病例，该病例显示Ewing 肉瘤断点区域 1/EWS RNA 结合蛋白 1 (EWSR1) - BEN 结构域 2 ( BEND2) 融合。患者出现下肢和躯干背痛、步态障碍和感觉迟钝。磁共振成像显示 T3-5 水平的髓内肿瘤，显示均匀的钆增强。用椎板切除术进行部分肿瘤切除。组织学检查显示上皮样肿瘤细胞的实体生长，显示出高细胞性、假乳头状结构、介入的透明纤维基质和一些有丝分裂。星形母细胞瘤被德国癌症研究中心甲基化分类器诊断为 HGNET- MN1 。通过荧光原位杂交 (FISH) 未检测到MN1改变，但EWSR1 - BEND2通过 FISH 和 RNA 测序检测融合。此前，曾报道一名患有EWSR1 - BEND2融合阳性脊柱星形母细胞瘤的儿童被归类为 HGNET- MN1。与此相结合，本案例提供了证据表明EWSR1 - BEND2融合在 HGNET- MN1的实体中被识别。总之，BEND2改变而不是MN1可能决定中枢神经系统 HGNET- MN1亚类的一个子集的生物学。