Hyperplasia of the Breast (Ductal or Lobular)

Hyperplasia is also known as epithelial hyperplasia or proliferative breast disease. It’s an overgrowth of the cells that line the ducts or the milk glands (lobules) inside the breast.

Ductal hyperplasia (also called duct epithelial hyperplasia) is an overgrowth of the cells that line the small tubes (ducts) inside the breast, while lobular hyperplasia is an overgrowth of cell lining the milk glands (lobules).  Ductal and lobular hyperplasia occur at about the same rate, and have about the same effect on breast cancer risk.

Hyperplasia is often described as either usual or atypical based on how the cells look under a microscope.

  • In usual hyperplasia, the cells look very close to normal.
  • In atypical hyperplasia (or hyperplasia with atypia), the cells are more distorted. This can be either atypical ductal hyperplasia (ADH) or atypical lobular hyperplasia (ALH).


Hyperplasia doesn’t usually cause a lump that can be felt, but it can cause changes that can be seen on a mammogram. It’s diagnosed by doing a biopsy. (A hollow needle may be used to remove a small piece of tissue that’s checked in the lab. Or, surgery may be done to take out the abnormal breast tissue.)

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:

  • Mild hyperplasia of the usual type: This does not increase the risk for breast cancer.
  • Moderate or florid hyperplasia of the usual type (without atypia), also known as usual hyperplasia: The risk of breast cancer is about 1½ to 2 times 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.


Most types of usual hyperplasia do not need to be treated. But if atypical hyperplasia (ADH or ALH) is found on a needle biopsy, more breast tissue around it might be removed with surgery to be sure that there is nothing more serious nearby, such as cancer. (This is more likely to be recommended for ADH than for ALH.)

Reducing breast cancer risk or finding it early

Atypical hyperplasia (ADH or ALH) is linked to a higher risk of breast cancer. Even though most women with atypical hyperplasia will not develop breast cancer, it's still important to talk with a health care provider about your risk and what, if any, options are best for you.

Options for women at high risk of breast cancer from atypical hyperplasia 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 journalists, editors, and translators with extensive experience in medical writing.

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Last Medical Review: September 10, 2019 Last Revised: September 10, 2019

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