Uterus-like mass of the ovary associated with endometrioid carcinoma.

We describe a solid and cystic right ovarian mass removed from a 38-year-old woman. The solid component, which had a central cavity lined by endometriotic tissue and surrounded by a thick muscle wall, strongly resembled a miniature uterus. The contiguous cystic mass was an endometrioid carcinoma. We review the literature and discuss the theories of histogenesis of uterus-like ovarian masses.