Polypoid Brenner tumor of the uterus.

Extraovarian Brenner tumors (BT) are very rare. We report such a tumor that was an intracavitary polyp in the uterus of a 63-year-old woman. The differential diagnosis included a pure transitional cell tumor, a mixed mullerian tumor, and a uterine tumor resembling an ovarian sex cord tumor. The histogenesis of BT remains controversial; in this particular case the location of the BT suggests a mullerian origin.