An Overview of Atypical Lobular Hyperplasia of the Breast

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Atypical lobular hyperplasia (ALH) occurs in the epithelial cells lining the lobes of the breast. Instead of one even layer of uniformly shaped cells, overgrowth yields several layers, with some cells being irregular in shape and size. Atypical lobular hyperplasia is not breast cancer, but it is considered a precancerous condition. Because your risk of breast cancer is higher than average if you have ALH, you will need close monitoring.

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ALH is similar to atypical ductal hyperplasia (ADH), which causes more cells to develop in the lining of the breast ducts (milk producing glands).

Also Known As

ALH is also known as lobular hyperplasia with atypia, mammary atypical lobular hyperplasia, epithelial atypical hyperplasia, and proliferative breast disease.


Atypical lobular hyperplasia typically doesn't cause any notable symptoms, though it may cause breast pain in some cases. Most women are unaware of the condition until they get the results of routine breast imaging.

That said, since atypical lobular hyperplasia can lead to breast cancer, make sure you bring any abnormalities you notice during a breast self-exam to the attention of your doctor. These may include: 

  • Breast swelling or chest pain
  • Pain in the armpit or traveling from the breast to the armpit
  • A breast lump or mass
  • Nipple discharge that is white, yellow, or bloody
  • Misshapen or uneven breasts


An exact cause of atypical lobular hyperplasia is unknown. Doctors believe it is a natural part of breast changes for some women as they get older. It often affects women over 35, but it can affect women regardless of age. It may also affect men but is very rare.

Risk factors of ALH are similar to those for other benign breast conditions, including:

  • Postmenopausal hormone use
  • Family history of breast cancer and benign breast conditions
  • Certain lifestyle factors, including over-consumption of alcohol, smoking, being overweight, and having an unhealthy diet


Imaging and a tissue biopsy are needed to confirm an atypical lobular hyperplasia diagnosis.

  • Mammogram: ALH appears as a cluster of microcalcifications on a mammogram.
  • Ultrasound: A breast ultrasound uses sound waves to reveal groups of microcalcifications.
  • Breast biopsy: A breast biopsy is the most definitive method for diagnosis of ALH. It allows a pathologist to determine the location and nature of your cells. The pattern of growth seen in atypical lobular hyperplasia is abnormal and may contain cells that are characteristic of lobular carcinoma in situ (LCIS)—an overgrowth of cells in the lobules.

In some cases—for example, when someone has a family history of breast or ovarian cancer, or is positive for a BRCA gene mutation—an excisional biopsy may be done to remove the suspicious tissue.


Some women with atypical lobular hyperplasia may benefit from undergoing surgery to remove abnormal cells and make sure no in-situ and invasive cancer cells are also present in the area. However, most cases of ALH do not require treatment.

It is difficult to predict which cases of atypical lobular hyperplasia will remain benign and which may become malignant, so surveillance is essential.

This will include extra screening mammograms and/or breast magnetic resonance imaging (MRIs) to identify any breast changes as early as possible. A commitment to risk-reduction strategies is also recommended.

While having atypical lobular hyperplasia increases one's lifetime risk of breast cancer by up to 2%, prevention methods have been found to reduce that risk by up to 70% in women with ALH or other high-risk breast conditions.

Your doctor will advise you to avoid oral contraceptives and hormone replacement therapy (HRT), as both further increase your risk of developing breast cancer. Adopting certain lifestyle strategies, such as getting regular exercise and eating a low-fat diet, can also help prevent the disease. For some, medication to reduce breast cancer risk may be recommended as well.

A Word From Verywell

Learning of any abnormality in your breast is concerning, but remember that atypical lobular hyperplasia is not cancer. It does, however, mean that prevention strategies are perhaps more important to you now than ever. Take control of your condition by doing all that you can to affect modifiable risk factors. Be sure you are clear about your recommended screening schedule, get regular checkups, and consider seeking the advice of health professionals, such as a nutritionist, to help you in your efforts.

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  1. Lobular Neoplasia (Atypical Lobular Hyperplasia and Lobular Carcinoma in Situ). Updated October 17, 2018.

  2. American Cancer Society. Hyperplasia of the Breast (Ductal or Lobular). Updated September 10, 2019.

  3. Mazzola E, Coopey SB, Griffin M, et al. Reassessing risk models for atypical hyperplasia: age may not matterBreast Cancer Res Treat. 2017;165(2):285–291. doi:10.1007/s10549-017-4320-7

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