摘要目的:观察肺动脉内膜肉瘤的临床病理特征，了解其基因改变情况。方法:分析中日友好医院2017年1月至2020年1月间行肺动脉内膜剥除术病例60例，收集其中5例肺动脉内膜肉瘤患者临床资料，采用HE染色、免疫组织化学染色及荧光原位杂交进行病理形态学观察，通过RNA测序方法分析肿瘤融合基因改变。结果:肺动脉内膜肉瘤检出率为8.3%（5/60），中位年龄49岁，女性多于男性，临床表现不特异。肿瘤由异型梭形细胞或上皮样细胞组成，可出现骨肉瘤及平滑肌肉瘤分化。肿瘤细胞可表达血小板源性生长因子受体α、细胞周期蛋白依赖性激酶4（CDK4）及MDM2，并伴有MDM2、CDK4及表皮生长因子受体基因共扩增。RNA测序检出多种框内融合基因改变。结论:肺动脉内膜肉瘤是一类罕见、高度异质性并伴有多基因复杂改变的低~未分化肉瘤，治疗效果不佳，预后差。

abstractsObjective:To describe the clinicopathological features of pulmonary artery intimal sarcoma (PAIS), and to understand its molecular alterations.Methods:Sixty cases of pulmonary artery endarterectomy performed at the China-Japan Friendship Hospital, Beijing, China from January 2017 to January 2020 were reviewed. Clinical data of 5 patients with pulmonary artery intimal sarcoma were collected. Hematoxylin-eosin staining, immunohistochemistry staining and fluorescence in situ hybridization (FISH) were performed to evaluate the pathological features. RNA sequencing was conducted to assess the fusion gene changes in PAIS.Results:The detection rate of PAIS was 8.3% (5/60), with the median age of 49 years and a female predominance. Their clinical manifestations were non-specific. Histopathological examination showed that the tumors were composed of malignant spindle or epithelioid cells, with various degrees of atypia. Focal heterologous osteosarcomatous or leiomyosarcomatous differentiation was noted. The tumor cells could express PDGFRA, CDK4 and MDM2 with co-amplification of MDM2, CDK4 and EGFR genes. RNA sequencing detected multiple in-frame fusions in the tumors.Conclusions:PAIS is a rare, highly heterogeneous, and poorly-or un-differentiated sarcoma accompanied by complex changes of multiple genes.It has no known effective treatments, and thus has a poor prognosis.