An uncommon surface epithelial tumor of the ovary (very rarely, testicular Brenner tumors have been reported). Previously known as transitional tumors due to histologic similarity to the urothelium. May have solid and cystic components. They are usually small. The majority are benign, but they can be malignant or borderline. Brenner tumors are usually asymptomatic and found incidentally during pelvic examination or laparotomy procedure. They are often discovered in association with other epithelial neoplasms. Patients are usually women aged 40-60 years. Treatment involves surgery to remove the tumor. If the tumor has not spread to surrounding body tissues, prognosis is usually good.