Non-Cancerous Breast Conditions

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Hyperplasia (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). Based on how the cells look under a microscope, the hyperplasia is called either ductal hyperplasia (also called duct epithelial hyperplasia) or lobular hyperplasia. Hyperplasia may be described as usual or atypical based on the pattern of the cells.

  • In usual hyperplasia, the pattern of cells is very close to normal.
  • The cells are more distorted in atypical hyperplasia (or hyperplasia with atypia).


Hyperplasia doesn’t usually cause a lump that can be felt, but can cause changes that can be seen on a mammogram. Diagnosis is made by a biopsy (where tissue is removed and checked under a microscope).


Women with hyperplasia, especially atypical hyperplasia, need to see the doctor more often. They may need frequent breast exams and yearly mammograms, because some types of hyperplasia are linked to a higher risk of breast cancer.

Some women with atypical hyperplasia choose to take medicine to lower their risk of breast cancer. More on this can be found in Medicines to Reduce Breast Cancer Risk.

How does hyperplasia affect your risk for breast cancer?

Different types of hyperplasia can affect breast cancer risk:

  • 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 atypical ductal hyperplasia [ADH] or atypical lobular hyperplasia [ALH]): The risk of breast cancer is about 3½ 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.

Last Medical Review: 03/16/2015
Last Revised: 04/21/2016