A smooth, solid or cystic fibroepithelial (fibroepithelial neoplasms) tumor, usually found in the ovaries but can also be found in the adnexal region and the kidneys. It consists of a fibrous stroma with nests of epithelial cells that sometimes resemble the transitional cells lining the urinary bladder. Brenner tumors generally are benign and asymptomatic. Malignant Brenner tumors have been reported. [MeSH]