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Breast Cancer

Hyperplasia of the Breast

Hyperplasia is an overgrowth of the cells that line the lobules (milk-producing glands) or ducts (small tubes) inside the breast. It is not cancer, but some types of hyperplasia are linked with a higher risk of developing breast cancer (see below). 

Hyperplasia can be described as either usual or atypical, based on how the cells look under a microscope.

  • In usual ductal hyperplasia, there is an overgrowth of cells lining the ducts in the breast, but the cells look very close to normal.
  • In atypical hyperplasia (or hyperplasia with atypia), the cells look more distorted and abnormal. This can be either atypical ductal hyperplasia (ADH) or atypical lobular hyperplasia (ALH).

Diagnosis of hyperplasia

Hyperplasia doesn’t usually cause a lump that can be felt, but it can sometimes cause changes that can be seen on a mammogram. It’s diagnosed by doing a biopsy, during which a hollow needle or surgery is used to take out some of the abnormal breast tissue for testing.

How does hyperplasia affect your risk for breast cancer?

Hyperplasia can affect your risk for breast cancer, but how much depends on what type it is:

  • Usual ductal hyperplasia (also known as moderate or florid hyperplasia of the usual type, without atypia): The risk of breast cancer is about 1½ to 2 times higher than that of a woman with no breast abnormalities.
  • Atypical hyperplasia (either ADH or ALH): The risk of breast cancer is about 4 to 5 times higher than that of a woman with no breast abnormalities. More details about pathology reports showing atypical hyperplasia can be found in Understanding Your Pathology Report: Atypical Hyperplasia.

Treatment of hyperplasia

Usual ductal hyperplasia is considered a normal finding in the breast and does not need to be treated. 

If either ADH or ALH is found in a needle biopsy sample, surgery may be recommended to remove more breast tissue around it. This is to be sure that there is nothing more serious, such as cancer, nearby. If ADH or ALH is found after a surgical biopsy, typically no other treatment is needed.

Reducing breast cancer risk or finding it early

Both ADH and ALH are linked to a higher risk of breast cancer. Even though most women with ADH or ALH will not develop breast cancer, it's still important to talk with a health care provider about your risk and what you can do about it.

Options for women at higher risk of breast cancer from ADH or ALH may include:

The American Cancer Society medical and editorial content team

Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as editors and translators with extensive experience in medical writing.

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Last Revised: January 25, 2022

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