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.

Causes of breast cysts

It is not known what causes breast cysts, but they are very common and particularly affect women aged 35 to 50 years.(1) Cysts are part of a benign process known as fibrocystic change. They are more common in women who take hormone replacement therapy.

Are breast cysts harmful?

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.

Diagnosis of cysts

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 detect it as a lump.(2)

Treatment of breast cysts

Cysts that do not cause symptoms do not require treatment. However, if a cyst is painful, or large enough to be felt, then the woman may choose to have it drained. This is done by inserting a fine needle into the lump, often guided by ultrasound, and drawing out the fluid. Although cysts are not harmful, draining them removes the lump and often relieves discomfort. The procedure only takes a couple of minutes and is done by a doctor. It may be slightly uncomfortable but is not usually painful. The fluid from a cyst may vary in colour ranging from straw-coloured to dark green. This is normal.(3) Your doctor will send the fluid to a laboratory for further testing if there are any concerns. Surgery is rarely recommended for removing cysts. Usually 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

BreastScreen Queensland encourages women to be aware of the normal appearance and feel of their breasts and to seek medical advice immediately if they have any concerns.If you have any questions or concerns, please do not hesitate to ask the staff at the BreastScreen Queensland Service or phone 13 20 50. We aim to provide you with high quality and friendly care at your visit. Early detection could save your life.


  1. National Breast Cancer Centre (2007) Causes of breast changes
  2. The NSW Breast Cancer Institute (2006) Breast cysts - An information guide for patients
  3. National Breast Cancer Centre (2006) The investigation of a new breast symptom- a guide for General Practitioners