Differential diagnosis, prognostic factors, and clinical treatment of proliferative Brenner tumor of the ovary.

Brenner tumors are rare ovarian tumors displaying benign, borderline or proliferative, and malignant variants. The case of a 63-year-old woman with a proliferative Brenner tumor is presented and the histomorphological differential diagnosis of this tumor entity is compared to that of its benign and malignant counterparts. Light microscopy, immunohistochemistry, and electron microscopy were performed to allow discrimination from the other subtypes. Despite a considerable overlap of pathological features the differential diagnosis of proliferative Brenner tumor could be established. Electron microscopy allowed assessment of characteristic infoldings of the nuclear membrane that proved to be a valuable ultrastructural criterion. Considering that the vast majority of Brenner tumors are benign, precise identification of the small proportion of malignant tumors allows the extent of surgical therapy to be adapted.