Brenner tumor of the ovary is a solid, abnormal growth (tumor) on the ovary. Most Brenner tumors are not cancerous (benign). About 5% of Brenner tumors are cancerous (malignant) or have a small chance of spreading beyond its original location (borderline). These tumors most often occur in women after menopause. They usually do not cause symptoms unless they are very large. When symptoms are present, they may include abdominal pain or vaginal bleeding. The cause of Brenner tumors is unknown. They are usually found by accident during surgery for another reason or during a routine doctor's examination. The diagnosis is made by microscopic examination of a piece of tumor obtained by a surgical biopsy. Treatment usually consists of surgery to remove the tumor. If a Brenner tumor has not spread into surrounding tissues or to more distant parts of the body, there is a good-to-excellent long-term outcome.

Most Brenner tumors do not cause any symptoms. If the tumor is quite large, it may cause pain or discomfort in one side of the abdomen. Women who are post-menopausal may experience vaginal bleeding as a symptom. If the Brenner tumor is malignant (cancerous), it may cause symptoms similar to other types of ovarian cancer, including abdominal swelling and difficulty with bladder control.

The cause of benign and malignant Brenner tumors is not known. About 30% of the time, benign Brenner tumors are found along with ovarian cancer. Women who have any type of ovarian cancer, including a malignant Brenner tumor, may want to ask their health care professional about genetic counseling because ovarian cancer is sometimes associated with a genemutation that can be inherited in families.

Approximately 90% of Brenner tumors of the ovary are first discovered by chance during surgery, a routine pelvic exam or an ultrasound. Brenner tumors are ultimately diagnosed by a surgical biopsy. Brenner tumors have specific microscopic findings that help guide diagnosis. Blood test for specific tumor markers may also be helpful.

The long-term outlook for individuals with cancerous or borderline Brenner tumors depends on the stage of the cancer when it is diagnosed and if the cancer has spread beyond the ovary. In general, the earlier the tumor is diagnosed and the less it has spread, the better the outcome.