目的探讨发生于子宫外的子宫内膜间质肉瘤(ESS)的病理组织学特征。方法通过光镜及免疫组化染色分析1例阴道原发的ESS,同时复习相关文献。结果原发于阴道的ESS与发生于子宫内的ESS形态十分相似,并找到了子宫内膜异位病灶,进一步证明了肿瘤的来源。结论 ESS是一种少见的肿瘤,发生在子宫以外部位就更为罕见,若肿瘤细胞分化差就极易误诊。免疫组化有助于诊断,但亦有片面性,须结合形态学。 Objective To investigate the histopathological features of endometrial stromal sarcoma (ESS) occurring outside the uterus. Methods One case of vaginal ESS was analyzed by light microscope and immunohistochemistry, and the related literatures were reviewed. Results The ESS originating in the vagina was similar to the morphology of ESS in the uterus and found the endometriotic lesion, which further proved the origin of the tumor. Conclusion ESS is a rare tumor that occurs even more frequently outside the uterus. Misdiagnosis can be easily performed if the tumor cells differentiate poorly. Immunohistochemistry helps diagnosis, but also one-sidedness, combined with morphological.