Atypical Hyperplasia of the Breast

What is Atypical Hyperplasia of the Breast?

Affecting breast cells, atypical hyperplasia is precancerous condition characterized by abnormal cell growth. The condition itself is not cancer. However, it can increase the odds a patient with the condition will develop breast cancer later in life since it results in an increased amount of abnormal cells through the cell division process.


It is not known what causes atypical hyperplasia to develop. It may lead to breast cancer since the condition affects the size and shape of cells and makes those misshapen cells more susceptible to damage and attack.


Being diagnosed with atypical hyperplasia does not automatically mean breast cancer will develop. Although the appearance of abnormal cells is considered the first stage in the eventual development and progression of breast cancer, which is why there is reason for concern when atypical hyperplasia is detected. Patients are encouraged to get regular breast cancer screenings (mammograms). If breast cancer is detected early, it is considered highly curable.

What are the Symptoms of Atypical Hyperplasia of the Breast?

Women diagnosed with atypical hyperplasia, according to one study, have a nearly 30 percent chance of developing breast cancer within 20-25 years from when the cell abnormalities are first detected. There are no specific symptoms associated with the condition.

When to see a doctor

  • There is a history of breast cancer in your family
  • You notice any unusual tenderness or swelling
  • There are unusual findings discovered during a routine mammogram

Atypical Hyperplasia of the Breast Causes

The cause of atypical hyperplasia is not completely clear, but it is suspected to be caused by the development of cancer. Atypical hyperplasia is a condition when breast cells change shape, number, shape, appearance, size, and/or pattern.

The way the cells appear defines the kind of atypical hyperplasia:

  • Atypical lobular hyperplasia produces irregular cells similar in nature to the breast lobules cells
  • Atypical ductal hyperplasia produces irregular cells similar in nature to the breast duct cells

This condition is perceived to be part of the conversion of healthy cells into potentially cancerous cells. The development of breast cancer includes hyperplasia, then atypical hyperplasia, noninvasive (in situ) cancer, and finally invasive cancer.

How is Atypical Hyperplasia of the Breast Treated?

A biopsy is necessary to positively identify and diagnose atypical hyperplasia. It is sometimes detected if a biopsy has been performed for another condition in the same area. The usual treatment for atypical hyperplasia is careful monitoring and follow-up examinations, including physical exams and image testing, to determine how the abnormal cells are developing.

Atypical Hyperplasia of the Breast Prevention

Atypical hyperplasia of the breast is not currently possible to prevent, but action can be taken that might help prevent its progression into breast cancer. The best course of action to take after atypical hyperplasia is diagnosed is to conduct a biopsy in which the tissue is extracted, to ensure there is not more potentially cancerous tissue underneath. If atypical hyperplasia was identified as part of a biopsy, additional information about the severity and size should be sought out. A cancer specialist should be seen if an individual is diagnosed with atypical hyperplasia.

Close follow-up is the typical approach to prevent further implications of atypical hyperplasia. If there is a record of breast cancer in the family, it would be wise to monitor for this frequently. A physician can recommend a suitable program for women who have a high risk. Programs for high-risk women conduct frequent follow-up sessions including yearly mammograms and clinical breast exams once every six months.

Tamoxifen may be diagnosed for either lobular or ductal atypical hyperplasia. Raloxifene (Evista) is another option for women who are postmenopausal. Each of these medications are taken once per day for five years and are distributed in pill form. In a study by the Breast Cancer Prevention Trial, Tamoxifen reduced the occurrence of breast cancer in women with atypical hyperplasia by 86%.

Last Reviewed:
September 13, 2016
Last Updated:
November 13, 2017
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