Abstract：
Certain undifferentiated round cell sarcomas displaying EWSR1::NFATC2 fusion have recently been reported, mostly in the bones. This report presents clinicopathological features of 3 additional EWSR1::NFATC2 fusion sarcomas of bone and soft tissues. We present 2 soft tissue and 1 bone tumors: A 62-year-old man with pain and a slowly growing, 8-cm-sized soft tissue mass in the anterolateral compartment of his right calf, along with multiple pulmonary metastatic lesions; a 63-year-old man with a 5-cm sized axillary mass of 4 months duration and a cystic renal mass; and a 53-year-old man with a complaint of leg pain was found to have a 2-cm diameter, intramedullary, lytic mass in the diaphysis of his left femur. Microscopic examination of the tumors in all patients revealed round to epithelioid cells arranged in cords and trabeculae in a myxohyaline stroma. Immunohistochemically, the tumor cells were positive for MIC2/CD99 (3/3), EMA (3/3), NKX3.1 (3/3), NKX2.2 (2/2), CD10 (2/2), and aggrecan (1/1), while negative for S100P and GFAP. Various keratins were also negative except focal AE1/AE3 positivity in the third tumor. By fluorescence in-situ hybridization, 2 tumors (#1 and #3) revealed EWSR1 gene rearrangement and amplification. Furthermore, 2 tumors (#1 and #2) displayed EWSR1ex8::NFATC2ex3 fusion with next-generation sequencing (NGS). The first patient was offered chemotherapy. However, he died of pulmonary metastasis. This report highlights the value of combining histopathological features and immunostains such as NXK3.1, NKX2.2, CD10, and aggrecan, along with EWSR1 testing for triaging these tumors for rare gene fusions by NGS that has prognostic implications.
摘要：
最近报道了某些显示EWSR1::NFATC2融合的未分化圆形细胞肉瘤，大部分在骨头里.本报告介绍了另外3种EWSR1的临床病理特征：骨和软组织的NFATC2融合肉瘤。我们提出了2个软组织和1个骨肿瘤：一个62岁的男人，疼痛和缓慢增长，右小腿前外侧区有8厘米大小的软组织肿块，伴随着多个肺转移性病变；一名63岁的男子，腋窝肿块大小为5厘米，持续时间为4个月，囊性肾脏肿块；一名患有腿部疼痛的53岁男子被发现直径为2厘米，髓内,他左股骨骨干处的溶解肿块。对所有患者的肿瘤进行显微镜检查，发现周围的上皮样细胞排列在粘液透明基质中的索和小梁中。免疫组织化学，肿瘤细胞MIC2/CD99（3/3）阳性，EMA（3/3），NKX3.1(3/3),NKX2.2(2/2),CD10(2/2),和aggrecan(1/1)，而S100P和GFAP阴性。除了第三肿瘤中的局灶性AE1/AE3阳性外，各种角蛋白也是阴性的。通过荧光原位杂交,2个肿瘤(#1和#3)显示EWSR1基因重排和扩增。此外，2个肿瘤(#1和#2)显示EWSR1ex8::NFATC2ex3与下一代测序(NGS)融合。第一位患者接受了化疗。然而,他死于肺转移。本报告强调了结合组织病理学特征和免疫染色的价值，如NXK3.1，NKX2.2，CD10和聚集蛋白聚糖，与EWSR1测试一起，通过NGS对这些肿瘤中的罕见基因融合进行分类，这具有预后意义。
