What are breast cysts?

Breast cysts are bubbles of fluid in the breast. They are like blisters. Breast cysts are benign (not cancer). They are common in females aged 35 to 50 years. They are also common in females taking hormone replacement therapy.

Types of breast cyst

In the breast, fluid is always being made. After being made, the fluid is reabsorbed. This means the fluid goes back into the breast tissue.

Breast cysts can happen if more fluid is produced than reabsorbed. During a female’s menstrual cycle, breast cysts may form or get larger. Sometimes breast cysts happen when a milk duct becomes blocked.

Most cysts are tiny. They are only a few millimetres in diameter. They usually develop quickly. Then, they stay the same size. Females often have more than one cyst. Larger cysts can be felt when examining your breasts. They can be either soft or firm. They should move easily in your breast.

It is not known why some females have more breast cysts than others.

What are the symptoms of breast cysts?

Breast cysts are benign (not cancer). They do not change to become cancer. Cysts are not dangerous. Breast cancer could happen in the same part of the breast as a cyst. But the cyst will not cause breast cancer.

Breast cysts can feel tender if you press on them. The breast area around a cyst may also feel tender or painful. This can happen even if you can’t feel a cyst. Breast cysts can be more painful before your period.

When should I see my doctor?

It is important to know how your breasts normally feel. This can help you notice any changes quickly. Some breast lumps may not be cysts.

You need to see your doctor if:

• you find a new lump in your breast or armpit
• part of your breast feels thick or swollen
• the skin on your breast is dimpled or red and itchy
• your nipple is painful, pulled in or has fluid coming out of it
• there is redness or flaky skin on your breast or nipple
• the size and shape of your breast has changed
• your breast is painful all the time

How are breast cysts diagnosed?

Larger breast cysts can usually be felt by you or your doctor. However, your doctor will need to order imaging tests to know what is causing your lump(s). Smaller cysts are often only found by an ultrasound or a mammogram.

An ultrasound helps your doctor see if your lump is solid or filled with fluid. Fluid filled lumps are usually cysts.

Sometimes your lump may be solid. Or it may have solid parts and fluid parts (a complex cyst). If this is the case your doctor may suggest another test called a biopsy. It is important to make sure that your lump is harmless.

How are breast cysts treated?

Breast cysts are harmless. They do not usually need to be treated. Sometimes breast cysts can be drained to take out the fluid. This may be needed if your cysts are painful. Your doctor may also recommend draining a cyst if it’s very large. This is so you won’t have to worry about it.

To drain a cyst, the doctor will use a very fine needle. This may feel a bit uncomfortable. Any pain will not last for very long. Draining a cyst usually only takes a couple of minutes for each cyst. The fluid inside the cyst may look clear or coloured. This is normal. It is nothing to worry about.

Draining your cyst will shrink it. Sometimes cysts come back. They are treated in the same way as the first cyst.

Resources and support

For more information about breast cysts and breast changes:

• Download the Breast Cysts brochure from the Westmead Breast Cancer Institute.
• Download the Breast Changes brochure from the National Breast Cancer Centre.
• Phone Breast Cancer Network Australia on 1800 500 258.