Non-Cancerous Breast Conditions

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Ductal or lobular hyperplasia

Hyperplasia is also known as epithelial hyperplasia or proliferative breast disease. It’s an overgrowth of the cells that line the ducts or the 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.

Based on the pattern of the cells, hyperplasia may be called usual or atypical. In usual hyperplasia, the pattern of cells is very close to normal. Atypical hyperplasia (or hyperplasia with atypia) is a term used when the cells are more distorted.


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

Link to cancer risk

Different types of hyperplasia affect breast cancer risk differently:

  • 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. Information about pathology reports showing atypical hyperplasia can be found in the document Understanding Your Pathology Report: Atypical Hyperplasia.

If you have hyperplasia, especially atypical hyperplasia, it usually means you will need to see your doctor more often. This may mean more frequent breast exams and a special effort to get 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 information on this topic can be found in our document Medicines to Reduce Breast Cancer Risk.

Last Medical Review: 03/16/2015
Last Revised: 06/10/2015