Ultrastructure of endometrial stromal sarcoma.

An endometrial stromal sarcoma from a 48-year-old woman was studied by light and electron microscopy. Ultrastructurally most of the tumor cells resembled the stromal cells of midproliferative endometrium. There was no evidence of a pericytic differentiation of the tumor cells. These findings lend further support to the concept of an endometrial histogenesis of stromal sarcoma.