MEIS1::NCOA1/2 fusion sarcomas are a recently described novel entity arising in a variety of locations with a predilection for the genitourinary tract and gynecologic organs. Despite multiple locoregional recurrences, these tumors are thought to behave in a low-grade malignant manner. Here we report a uterine MEIS1::NCOA2 fusion sarcoma with lung metastasis. The patient was a 47-yr-old woman with a history of abnormal uterine bleeding who was found to have a myometrial mass confirmed by pathology to be uterine sarcoma. The tumor was predominantly composed of monotonous spindle cells with scant cytoplasm, crowded nuclei, and brisk mitotic activity, growing in a fascicular and streaming pattern. The morphologic and immunophenotypic features were nonspecific and a diagnosis of high-grade uterine sarcoma with a differential of leiomyosarcoma versus high-grade endometrial stromal sarcoma was rendered. At the 27-mo follow-up, the patient was found to have a lung metastasis consisting of a monotonous round cell sarcoma. A retrospective RNA-based and DNA-based next-generation sequencing of the primary uterine sarcoma revealed a MEIS1::NCOA2 gene fusion, a c.94G>C/p.D32H mutation in exon 3 of CTNNB1 gene, HMGA2, and CDK4 gene amplification, and an intermediate/marginal level of MDM2 gene amplification. Polymerase chain reaction–based molecular analysis further demonstrated that the MEIS1::NCOA2 gene fusion and CTNNB1 somatic mutation were also present in the lung metastasis. This case represents the first case of such gynecologic sarcoma with distant (lung) metastasis, and the second metastatic case among all reported MEIS1::NCOA1/2 fusion sarcomas, highlighting the malignant metastatic potential of this emerging entity. Our case also indicates that HMGA2/CDK4/MDM2 region amplification and CTNNB1 somatic mutation might be recurrent genetic events in this rare sarcoma subtype.

MEIS1::NCOA1/2融合肉瘤是最近描述的一种新实体，发生于多个部位，好发于泌尿生殖道和妇科器官。尽管有多个局部区域复发，但这些肿瘤被认为以低度恶性方式表现。在这里，我们报告了子宫MEIS1::NCOA2融合肉瘤伴肺 转移。患者女，47岁，有异常子宫出血史，查出子宫肌层肿块，经病理证实为子宫肉瘤. 肿瘤主要由单调的梭形细胞组成，细胞质稀少，细胞核拥挤，有丝分裂活跃，呈束状和流状生长。形态学和免疫表型特征是非特异性的，诊断为高级子宫肉瘤，与平滑肌肉瘤和高级子宫内膜间质肉瘤不同。在 27 个月的随访中，发现患者有肺 转移，包括单调的圆形细胞肉瘤。原发性子宫肉瘤的基于 RNA 和 DNA 的回顾性下一代测序揭示了MEIS1::NCOA2基因融合， CTNNB1基因外显子 3 的 c.94G>C/p.D32H 突变，HMGA2和CDK4基因扩增，以及MDM2基因扩增的中间/边缘水平。基于聚合酶链反应的分子分析进一步证明，MEIS1::NCOA2基因融合和CTNNB1体细胞突变也存在于肺 转移中。本病例是此类妇科肉瘤远处（肺）转移的首例，也是所有报道的MEIS1::NCOA1/2中的第二例转移病例。融合肉瘤，突出了这种新兴实体的恶性转移潜能。我们的病例还表明，HMGA2/CDK4/MDM2区域扩增和CTNNB1体细胞突变可能是这种罕见肉瘤亚型的复发性遗传事件。