Benign Breast Conditions: Breast Cysts

June 2019
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This fact sheet describes the benign breast condition of simple breast cysts, or a collection of fluid in a sac. If breast cysts are detected during a mammogram, the woman will be recalled for assessment. For BreastScreen Aotearoa professionals to use in the programme.

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June 2019
November 2016
Leaflet A4
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The full resource:

Your mammogram (breast X-ray) from BreastScreen Aotearoa showed an area of change and you were asked to come back for assessment. The change that showed up on your mammogram was not breast cancer. It was a simple breast cyst.

What is a simple breast cyst?

A simple breast cyst is a collection of fluid in a sac in the breast. It may occur as a single cyst or several cysts.

What is known about them?

  • You may not even be aware that you have them.
  • They may present as new lumps.
  • They may appear overnight or rapidly.
  • They may be painful or painless.
  • They can occur in either one breast or both breasts.
  • They can change in size or shape and may contain thin or thick fluid.
  • They can feel soft, firm or hard; smooth or mobile.
  • They can come and go or change size during the menstrual cycle.

What causes them?

Simple breast cysts occur because a few milk- producing breast glands and ducts overreact to normal hormonal changes.

How common are they?

Simple breast cysts are very common and can occur in women of any age. They are most common in the 30- to 50-year age group.

They usually disappear after menopause, but in some women they can last throughout life. After menopause breast cysts are more likely to occur if women are taking hormone replacement therapy.

Can they be prevented?

Because cysts occur in response to normal female hormones, there is no known way to prevent them. You will stop developing new cysts when you stop producing hormones sometime after menopause. Hormone replacement therapy can cause new cysts to develop.

How are simple breast cysts confirmed?

Sometimes simple breast cysts may show up on a routine mammogram. An ultrasound scan will help us decide that these are simple breast cysts.

In the past, surgery was used to diagnose simple breast cysts, but with the use of ultrasound this is no longer required.

What is done about them?

Simple breast cysts are usually left alone.

Sometimes the ultrasound will not show the typical appearance of simple breast cysts and a needle biopsy may be necessary to make sure they are simple breast cysts.

If simple breast cysts are very uncomfortable, they may be drained for pain relief.

Occasionally, they can refill or return.

Do they turn into cancer?

No, and simple cysts do not increase your risk of getting breast cancer.

If you notice new or growing breast lumps, do not assume they are simple breast cysts, even if you have had simple breast cysts in the past. See a doctor.

What happens now?

You should continue to have mammograms at the normal two-yearly interval.

BreastScreen Aotearoa will invite you for your next mammogram when it is due.

For more information

If you have questions not answered by this sheet, ask the breastcare nurse you saw at BreastScreen Aotearoa.