Introduction/Background*To present the clinicopathological features of cases with Endometrial Stromal Nodule (ESN) and Endometrial Stromal Sarcoma (ESS) in our center.

Methodology The cases diagnosed between 2008-2020 were re-examined microscopically. The information for clinical follow-up were retrieved from the hospital archives, retrospectively.

Result(s)*ESN cases consisted of 11 patients between the ages of 41-68 (mean 51,8), Low Grade Endometrial Stromal Sarcoma (LGESS) cases consisted of 13 patients between the ages of 24-53 (mean 44), High Grade Endometrial Stromal Sarcoma (HGESS) cases consisted of 9 patients between the ages of 60-84 (mean 71,2).

Mean tumor size was 3,3 cm (1,7-8 cm) in ESN cases; 6,4 cm (1-13 cm) in LGESS cases; 6,5 cm (4,5-9 cm) in HGESS cases.

In LGESS cases, the number of mitosis in 10 high power fields was 0-7 (average 2,8); In HGESS cases it was counted as 10-45 (average 22). Ki-67 proliferation index was evaluated as 2-5% (mean 3.8%) in LGESS cases; as 30-100% (mean 68%) in HGESS cases.

At the median follow-up of 56,5 months (range, 21-147 months), all of 11 ESN cases are alive. At the median follow-up of 60 months (range, 47-144 months), 1 of 13 case of LGESS have died (%8). At the median follow-up of 8 months (range, 1-53 months), 5 of 9 cases of HGESS have died (%56). Distant metastasis was seen only in 1 case of 9 HGESS, the location of metastasis is lung.

85% of cases with LGESS were presented in stage I and,%15 were in stage II. 37.5% of cases with HGESS were presented in stage I, 50% were in stage III and 12.5% were in stage IV.

Conclusion*Endometrial stromal neoplasms are rare lesions of the uterus, usually presenting in the postmenopausal period. The histological type and stage of these lesions are directly related to the clinical course. Average mitotic activity and Ki-67 levels can also provide information in the direction of the clinical course.