Non-cancerous tumours and conditions of the ovary

A non-cancerous (benign) tumour of the ovary is a growth that does not spread (metastasize) to other parts of the body. Non-cancerous tumours are not usually life-threatening. Benign conditions of the ovary, such as cysts and polycystic ovaries, are also non-cancerous.

Benign tumours and cysts usually do not cause symptoms. Symptoms that sometimes occur are:

• unusual bleeding from the vagina
• pain in the abdomen as the tumour or cyst increases in size

Benign tumours are usually treated by surgery to remove the part of the ovary that contains the tumour or the entire ovary.

Benign epithelial tumours are the most common type of benign ovarian tumour. They start from the cells that cover the outer surface of the ovary.

Their makeup can be mainly cystic (called cystadenoma), mainly solid (called adenofibroma) or mixed (called cystadenofibroma). Types of benign epithelial tumours are:

• serous (e.g. serous cystadenoma, if mainly cystic)
• mucinous (e.g. mucinous adenofibroma, if mainly solid)
• cystadenofibroma
• Brenner tumours

Benign stromal tumours start from the connective tissue cells that hold the ovary together. The tumours may make the female hormones estrogen and progesterone. Types of benign stromal tumours include:

• thecoma
• fibroma
• fibrothecoma – a mixed tumour with both thecoma and fibroma cells
• Leydig cell tumour
• stromal luteoma

Benign germ cell tumours start from the cells that produce the eggs (ova). They are also called mature cystic teratomas or dermoid cysts. Most benign germ cell tumours develop during a woman’s reproductive years (teens through 40s).

Ovarian cysts are a common benign condition. A cyst is a fluid-filled sac that forms on the surface of or inside an ovary. Most ovarian cysts are functional cysts, which means the ovary continues to work as normal with the cyst. Functional cysts form during normal ovulation (release of the egg from the ovary). Follicular cysts and corpus luteum cysts are functional cysts.

Cysts usually go away, without treatment, within a few months. They may also be removed with surgery.

With polycystic ovaries, changes to the hormone cycle and ovulation process mean that the eggs don’t mature and are not released from the ovaries (called ovulation). Instead, the eggs form very small cysts within the ovaries. The ovaries may get bigger and develop a thick outer layer.

Many women with polycystic ovaries have few periods, or none at all, and usually have difficulty getting pregnant.

Treatment of polycystic ovaries includes:

• hormone therapy with progestins
• oral contraceptives
• infertility treatments for women who want to get pregnant