Benign Brenner Tumor in an Ectopic Ovary: A Case Report and Review of Literature.

Supernumerary ectopic ovaries are very rare, with fewer than 40 cases of isolated supernumerary ovaries reported in the literature since their discovery in 1864. Tumors arising in ectopic ovaries are also extremely rare, with only a handful of reports in the literature. Given the rarity of this combination of findings, we report a case of a 68-yr-old woman incidentally found to have a 4.7 cm solid retroperitoneal mass adjacent to the liver, diagnosed as a benign Brenner tumor arising in a supernumerary ectopic ovary. To our knowledge, there has been only one previously reported case of Brenner tumor arising in this unusual setting.