What is a breast cyst?

This page was reviewed under our medical and editorial policy by

Daniel Liu, MD, Plastic and Reconstructive Surgeon

This page was reviewed on February 8, 2022.

Breast cysts are fluid-filled sacs that are among the most common breast lumps a woman may have. They may also be a cause of other breast symptoms—from pain to, potentially, nipple discharge.

Many women develop noncancerous changes in their breast tissue. It’s one of the conditions known as fibrocystic breast disease, which includes fluid-filled cysts. A cyst may show up in one or both breasts at the same time and in different parts of the breast. Some cysts are so small that patients don’t feel a lump.

For many patients, breast cysts don’t have symptoms: Only about 7 percent of women have a breast cyst that may be felt with the hand.

Simple fluid-filled cysts form from fluid buildup in the breast glands. Microcysts are tiny and may only be spotted under a microscope. Macrocysts, on the other hand, may span from 1 to 2 inches.

Then there are complex cysts, which are either solid or filled with fluid and solids. A complex breast cyst may require a biopsy and drainage to check the cells, a procedure designed to determine whether the cyst is cancerous. On rare occasions, complex cysts are cancerous or increase the risk of breast cancer later.


Women with cysts may notice their breasts feel more painful before menstruation. In addition to tenderness and, possibly, one or more lumps, they may also experience nipple discharge that is clear or slightly cloudy.

Oftentimes, a cyst is detected on a mammogram, and it’s usually not a cause for concern.

Risk factors

Breast cysts are most common for women who are premenopausal, which typically describes those who are about age 30 to 50. Although less common, menopausal and postmenopausal women may still develop one. This may be especially true if they’re taking menopausal hormone replacement therapy, which is meant to reduce the symptoms of menopause and long-term biological changes, including bone loss. Hormone therapy uses estrogen and sometimes progestin, a synthetic hormone similar to progesterone.

Possible causes

It’s unclear why cysts develop. Some link them to caffeinated foods and drinks—coffee, tea, soda and chocolate. Some women report that their cysts become less bothersome after avoiding caffeine, according to the American Cancer Society. But studies have not found a clear link to support that conclusion.


Diagnosis is typically done through:

During a doctor’s visit, patients should be prepared to share:

  • Detailed information about what they’re experiencing, including a description of the pain and whether it’s affected by the menstrual cycle
  • Recent injuries to that area
  • Skin or nipple changes, such as nipple discharge
  • Full history of past medical and surgical issues
  • Age that menstruation and menopause, if applicable, started
  • Family history or personal history of breast cancer

The doctor will perform a physical exam to evaluate the health of the patient’s breasts, neck and chest, as well as the area under the arms.

Imaging exams may include:

  • Ultrasound: The ultrasound uses sound waves to reveal whether a mass is solid or filled with fluid. This procedure is used in younger women who may have more dense breast tissue.
  • Mammogram: This imaging test is a type of X-ray that takes images while the breast is pressed between plastic plates. In some cases, women with dense breasts may undergo a mammogram and an ultrasound.
  • Magnetic resonance imaging (MRI): This exam uses magnet radio waves to create an image. It may be used as an adjunct to other imaging tests in patients at higher risk for breast cancer when results are unclear.

Imaging may be followed by a FNA or CNB. These procedures may help to confirm the diagnosis by collecting fluid and/or tissue.

  • FNA uses a needle to drain fluid from the cyst.
  • CNB removes small pieces of breast tissue. Known as cores, these pieces are about the size of a grain of rice.

These procedures are not always needed for diagnosis. They’re usually outpatient procedures performed in a doctor’s office or clinic.

Questions your doctor may ask about breast cysts

Be prepared for your doctor to ask questions about your breast cysts at your visit, including:

  • How long ago did you notice the breast lump or cyst?
  • Are you experiencing breast pain? How severe would you describe the pain?
  • Has the size of your breast cyst changed over time?
  • Does the cyst change at all during your menstrual cycle?
  • Have you experienced nipple changes or nipple discharge?
  • Do you have a family history of breast cancer?
  • Have you ever had a mammogram? If so, when was your last one?
  • Have you ever experienced a breast injury?
  • Have you ever had surgery around your breasts, underarms or collar bone?

Treatment options

Once confirmed, a simple breast cyst doesn’t usually require treatment. Doctors may recommend monitoring the cyst over time.

If the patient is experiencing pressure and breast pain, doctors may drain the cyst, removing fluid and cells through the FNA process. A cyst also may be drained if its size is likely to interfere with a clinical breast exam. It’s possible the cyst will fill back up with fluid later or go away over time.

A breast cyst may be surgically removed if it keeps returning and causing symptoms.

To ease symptoms, doctors may recommend an over-the-counter pain reliever, such as acetaminophen or ibuprofen. For more serious symptoms, some doctors may prescribe hormones, including oral contraceptives, tamoxifen and androgens. However, these may have serious side effects, so they’re typically reserved for more severe cases.

Follow-up care may include:

  • For a simple cyst, imaging is typically performed again after four to six weeks—but this may not be recommended unless symptoms have developed.
  • Doctors would likely monitor a complex cyst (also referred to as a complicated cyst) more closely, conducting follow-up imaging every six to 12 months if a breast biopsy came back benign (noncancerous). This surveillance would usually continue for about two years if there were no changes. If there were changes, a repeat biopsy or cyst removal may be the next step.

Most breast cysts are benign. In the rare instances when a cyst is malignant, doctors would use the same therapeutic approaches as for breast cancer.

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