Background: Undifferentiated round-cell sarcomas (URCSs) of soft tissue and bone are a group of clinically heterogeneous tumors. Diagnosis of these malignancies is based mainly on recurrent genetic alterations. The most common and the best known representative of this group is Ewing sarcoma (ES) which is characterized by gene fusions including EWSR1 or FUS and ETS transcription factors family. Other newly described entities are CIC-rearranged sarcoma, sarcoma with BCOR genetic alterations, and round-cell sarcoma with EWSR1-non-ETS fusions. All these novel tumors are known as Ewing-like sarcomas. Summary: It is believed that morphologic features of ES and Ewing-like sarcomas vary only slightly or even that cytomorphology is not relevant. But differences are usually obvious, and some cytologic findings, such as spindle cells, connective tissue fragments, or myxoid stroma, are typical for Ewing-like sarcomas but not for ES. Each of these entities is also characterized by different immunoprofiles. The aim of this review was to summarize cytomorphologic and immunohistochemical features of URCS and compare them with other small round-cell tumors. Key Messages: Cytology can be successfully used in URCS diagnosis as a complementary tool for core-needle biopsy or even alone in selected cases, especially in recurrent and metastatic tumors. Knowing the morphologic and immunohistochemical differences between URCS is essential to provide appropriate ancillary studies and make a definitive diagnosis.
Acta Cytologica

中文翻译：

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骨和软组织未分化圆细胞肉瘤的细胞学：尤文肉瘤还是非尤文肉瘤，这是个问题

背景：软组织和骨的未分化圆细胞肉瘤（URCSs）是一组临床异质性肿瘤。这些恶性肿瘤的诊断主要基于复发性遗传改变。该组最常见和最著名的代表是尤文肉瘤 (ES)，其特征在于基因融合，包括 EWSR1 或 FUS 和 ETS 转录因子家族。其他新描述的实体是 CIC 重排肉瘤、具有 BCOR 基因改变的肉瘤和具有 EWSR1-非 ETS 融合的圆细胞肉瘤。所有这些新的肿瘤都被称为尤文样肉瘤。概括：人们认为 ES 和 Ewing 样肉瘤的形态学特征仅略有不同，甚至与细胞形态学无关。但差异通常很明显，一些细胞学表现，如梭形细胞、结缔组织碎片或粘液样间质，是尤文样肉瘤的典型表现，而不是 ES 的典型表现。这些实体中的每一个也具有不同的免疫特征。本综述的目的是总结 URCS 的细胞形态学和免疫组织化学特征，并将其与其他小圆细胞肿瘤进行比较。关键信息：细胞学可以成功地用于 URCS 诊断，作为芯针活检的补充工具，甚至可以单独用于特定病例，特别是在复发性和转移性肿瘤中。了解 URCS 之间的形态学和免疫组化差异对于提供适当的辅助研究和做出明确诊断至关重要。
细胞学学报