Breast cysts

Category: Women's Health

Topic: Breast Disorders

A breast cyst is a fluid-filled sac that develops within breast tissue. These sacs form when normal fluid-producing glands in the breast enlarge or become blocked.

Breast cysts may be solitary, but are often multiple, and can be tiny or several centimetres in diameter. When they become large, they can often be felt as lumps that move easily and which can be smooth, soft, firm or hard. Cysts, or the area around the cyst, may be tender to touch.

Many women have concerns that a cyst is, or will become, cancer. Simple breast cysts are not cancers and do not change into breast cancer. However, in very rare cases, cysts may have cancers growing within them or very close to them.


It is not known what causes breast cysts, but they are very common and particularly affect women aged 30 to 50 years.

Cysts are part of a benign process known as fibrocystic change. Over the age of 50, breast cysts are more common in women who take hormone replacement therapy.


Most cysts are very small, cannot be felt, and do not cause symptoms. Many women have cysts without knowing it, and usually do not require treatment. Sometimes cysts are seen on a mammogram or ultrasound that has been performed for another reason. In the case of a larger cyst, women may feel it as a lump.


Cysts that do not cause symptoms do not require treatment.

If a cyst is painful, or large enough to be felt, you may choose to have it drained. This is done by a doctor inserting a fine needle, usually guided by ultrasound, and drawing out the fluid. Although cysts are not harmful, draining them removes the lump and may relieve discomfort. The procedure is uncomfortable but not usually painful. Cysts that are not drained usually improve on their own over time.

The fluid from a cyst may vary in colour ranging from straw-coloured to dark green. This is normal. Your doctor will send the fluid to a laboratory for further testing if there are any concerns.

Surgery is rarely recommended for removing cysts. Only cysts that keep returning after repeated drainage, or that show worrying features on x-ray, ultrasound or from pathology testing need to be removed with an operation.

More information

Women of all ages should be aware of the normal look and feel of their breasts and see their GP if they notice any changes.