Endometrial stromal sarcoma (ESS) is a rare malignant neoplasm of the uterus. We report the first case of undifferentiated ESS (UES) coexistent with grade 1 endometrioid adenocarcinoma in a 73-year-old female who presented with irregular vaginal bleeding for 4 days after menopause 20 years. Imaging examination including Magnetic Resonance Imaging (MRI) demonstrated multi-node reflection in uterine cavity without metastatic lesions, and the endometrium essentially normal. Grossly, a grey-red breakable polypoid tumor of 4.5×3.0×2.0 cm was recognized in the posterior uterine wall with surrounding slight rough endometrium. Microscopically, the tumor was composed of a larger component of undifferentiated stromal sarcoma that was distinct from a smaller endometrioid adenocarcinoma. The separate components of the tumor could be supported in immunohistochemical studies. There was no sign of recurrence for postoperative 6 months.
Keywords: Uterus; immunohistochemistry; stromal tumor.