Endometrial stromal sarcoma involving the placenta

This report presents two cases of endometrial sarcoma tumor detected in decidua submitted with placentas for pathologic evaluation. The first patient had low-grade endometrial stromal sarcoma discovered in the omentum and decidua at the time of a cesarean section for placenta previa. The second patient underwent a cesarean section for breech presentation and was noted to have a mass beneath the placenta that was histologically compatible with low-grade endometrial stromal sarcoma. We believe these to be the first reported cases of endometrial stromal sarcoma involving the decidua. These findings should elevate awareness that endometrial stromal tumors may be detected during placental examination.