endometrial stromal nodule endometrial stromal nodule an endometrial stromal nodule is a noninfiltrative, circumscribed proliferation of endometrial stromal cells and is a benign subtype of endometrial stromal tumor. the appearance of the cells is identical to normal endometrial stromal cells. this can only be differentiated from low-grade endometrial stromal sarcoma by confirming lack of infiltration. endometrial stromal nodule the differential includes cellular leiomyoma. diagnosis may be aided by immunostaining; endometrial stromal nodules are positive for cd10; leiomyomas are positive for caldesmon and desmin (and sometimes cd10).