5589 Background: To determine the incidence of adnexal and lymph node (LN) metastases in endometrial stromal sarcoma (ESS). Methods: We identified all cases evaluated at our institution with a diagnosis of ESS from January 1, 1980 to December 31, 2007. All uterine pathology was reviewed at our center. High-grade or undifferentiated tumors and ESS arising in extrauterine sites were excluded. Pertinent clinical data were abstracted from electronic medical records. Appropriate statistical tests were performed using SPSS 15.0. Results: We identified 91 cases with ESS. All except two underwent hysterectomy. Eighty-four cases (92%) underwent salpingo-oophorectomy (bilateral in 81 [96%]). Adnexal metastases were identified in 8 (9.5%) of 84 cases. All adnexal metastases were manifested by gross adnexal tumor and occurred in patients with other gross pelvic extrauterine disease. Seven of these 8 patients also had lymph-vascular space invasion (LVSI). LVSI status was not reported in the other patient. In patients with gross pelvic extrauterine disease, adnexal metastasis did not affect survival. LN metastases were identified in 8 (24%) of the 34 patients who underwent LN evaluation. Thirty-three evaluations were performed intraoperatively and one was via postoperative CT-guided biopsy of an enlarged LN. Five of the 8 cases with LN metastases had LVSI. LVSI status was not reported in the other 3 cases. Of 20 patients with disease grossly limited to the uterus and grossly normal LN, 2 (10%) had LN metastases. Both of these cases had LVSI and extensive myoinvasion approaching the serosa. Four of the remaining 6 patients with LN metastases had grossly positive LN and other gross extrauterine disease. The final 2 patients had grossly positive LN without other extrauterine disease. Conclusions: The incidence of LN metastases in ESS is most commonly associated with gross extrauterine disease, extensive myoinvasion and LVSI. However, since myoinvasion and LVSI status often are not assessable at the time of initial hysterectomy, LN dissection remains a reasonable option at primary surgery. The rate of adnexal metastasis appears to be negligible in the absence of gross adnexal and extrauterine tumor, but there may be a role for oophorectomy in the hormonal management of ESS. No significant financial relationships to disclose.