Brenner tumours (aka Transitional cell tumours) are part of the surface epithelial-stromal tumour group of ovarian neoplasms. These are almost always benign and incidental findings on pelvic examination or at laparotomy.

On gross pathological examination, they are solid, sharply circumscribed and pale yellow-tan in colour. Histologically, there are nests of transitional-type epithelial cells with longitudinal nuclear grooves (coffee bean nuclei) lying in abundant fibrous stroma.