Understanding Breast Cysts

Cross section of breast with cyst and chest wall.

A breast cyst is a fluid-filled sac that forms in the breast tissue. You can have one or more cysts at a time. They can occur in one or both breasts. Breast cysts can be soft or firm and vary in size. In most cases, they are not cancer (benign). Having breast cysts does not increase your risk for breast cancer.

What causes a breast cyst?

Experts don’t know the exact cause of breast cysts. They think that cysts form because of hormone changes that happen during a woman’s menstrual cycle. They are most common in women ages 35 to 50.

Symptoms of a breast cyst

Often, a breast cyst has no symptoms. The cyst may have been found during a breast exam or imaging test. If symptoms do occur, they can include:

  • A round or oval lump in the breast that can be seen or felt

  • Pain, discomfort, or soreness around the lump

  • A lump that grows larger or that feels more painful and tender just before your period

Treatment for a breast cyst

Most breast cysts do not need treatment. They may even go away on their own. Breast cysts that are very painful or large may need to be treated. Options include:

  • Drainage (aspiration) of the cyst. The healthcare provider uses a needle and syringe to remove the fluid from the cyst.

  • Surgical removal of the cyst. The provider cuts the cyst out. It may need to be drained first.

Possible complications of a breast cyst

A breast cyst may go away but then form again. This can happen even after treatment.

When to call your healthcare provider

Call your healthcare provider right away if you have any of these:

  • Fever of 100.4°F (38°C) or higher, or as directed

  • Pain or soreness in the breast that doesn’t go away or that gets worse

  • An abnormal lump in the breast

  • A change in skin color over the breast

  • Dimpling or puckering of the skin over the breast

  • A nipple that becomes pulled in (retracted)

  • Unusual, dark, or bloody discharge from a nipple