Mixed mesodermal tumor and clear cell carcinoma arising in ovarian endometriosis.

A case is reported of clear cell carcinoma, arising as several papillary masses from the lining of an endometrial cyst within the ovary, associated with a mixed mesodermal tumor arising in the stalk of the largest papillary nodule. The origin of this tumor from within a focus of endometriosis lends support to the theory that both the epithelial and mesodermal components are of Müllerian (Paramesonephric) origin.