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Abstract：
BCL6 corepressor-cyclin B3 (BCOR-CCNB3) fusion sarcoma was classified as an emerging subgroup of undifferentiated small round cell sarcoma in 2020. The incidence of BCOR-CCNB3 fusion sarcoma is reportedly 1.5-14% among undifferentiated unclassified sarcomas, representing a rare entity among primary malignant bone tumors. The present study reports a case of BCOR-CCNB3 fusion sarcoma in the proximal tibia of a boy. A 12-year-old boy presented with a 6-month history of knee pain and a slowly growing mass in the anteromedial aspect of the left proximal tibia. Plain radiography and computed tomography of the knee demonstrated a lytic lesion with cortical destruction of the proximal tibia. Magnetic resonance imaging showed the bone tumor expanding into soft tissue with almost homogeneous hypointensity on T1-weighted imaging and slightly hyperintensity on T2-weighted imaging. On histopathological evaluation, the tumor comprised a proliferation of small, round to ovoid-shaped mesenchymal cells without osteoid formation. Histopathologically, BCOR-CCNB3 sarcoma of bone was finally diagnosed based on immunohistochemical staining and additional molecular analyses. The patient underwent bone tumor resection followed by pre- and post-operative chemotherapy according to a Ewing sarcoma protocol. The patient showed no evidence of local recurrence or distant metastasis at 12 months after completion of adjuvant chemotherapy. We present herein an additional case of BCOR-CCNB3 sarcoma of the proximal tibia, and review the relevant literature on BCOR-CCNB3 sarcoma of bone.
摘要：
BCL6协同抑制因子细胞周期蛋白B3（BCOR-CCNB3）融合肉瘤在2020年被归类为未分化小圆细胞肉瘤的新兴亚组。据报道，在未分化的未分类肉瘤中，BCOR-CCNB3融合肉瘤的发生率为1.5-14%。代表原发性恶性骨肿瘤中的罕见实体。本研究报告一例男孩胫骨近端BCOR-CCNB3融合肉瘤。一个12岁的男孩，有6个月的膝盖疼痛史，左胫骨近端前内侧肿块缓慢增长。膝关节的X线平片和计算机断层扫描显示出溶解性病变，胫骨近端皮质破坏。磁共振成像显示，骨肿瘤在T1加权成像上扩张成软组织，几乎均匀的低张力，而在T2加权成像上则略微高强度。关于组织病理学评估，肿瘤包括小的增殖，无类骨质形成的圆形至卵形间充质细胞。组织病理学,BCOR-CCNB3骨肉瘤最终根据免疫组织化学染色和其他分子分析诊断。患者接受了骨肿瘤切除术，然后根据尤文肉瘤方案进行了术前和术后化疗。患者在完成辅助化疗后12个月没有出现局部复发或远处转移的迹象。我们在此介绍另一例胫骨近端BCOR-CCNB3肉瘤，并对BCOR-CCNB3骨肉瘤的相关文献进行综述。
