Cystic variant of endometrial stromal sarcoma: report of two cases.

Endometrial stromal sarcoma is an uncommon tumor representing 0.2% of all uterine neoplasm and 15% to 26% of uterine sarcomas. Endometrial stromal sarcoma has a gross appearance as single nodule, multiple masses, or a poorly demarcated lesion with occasional cystic degeneration; rarely, it shows a cystic multilocular feature. We report 2 cases of endometrial stromal sarcoma with a prominent cystic appearance, forming multilocular cystic mass, detected by ultrasonography. The differential diagnosis among multicystic endometrial stromal sarcoma and cystic uterine tumors might be very difficult.