Skip to main content

ACS & ASCO are Stronger Together: Cancer.Net content is now available on


Your Breast Pathology Report: Atypical Hyperplasia (Breast)

Biopsy samples taken from your breast are studied by a doctor with special training, called a pathologist. After testing the samples, the pathologist creates a report on what was found. Your doctors will use this report to help manage your care.

The information here is meant to help you understand some of the medical terms you might see in your pathology report after a breast biopsy, which might be a needle biopsy or a surgical (open) biopsy. 

In a needle biopsy, a hollow needle is used to remove samples from an abnormal area in your breast. In some situations, a surgical biopsy might be needed. This can be either an incisional biopsy, in which only part of an abnormal area is removed, or an excisional biopsy, which removes the entire abnormal area, often with some of the surrounding normal tissue. An excisional biopsy is much like a type of breast-conserving surgery called a lumpectomy. 

What is hyperplasia?

The normal breast is made of milk ducts (tiny tubes) that end in a group of sacs called lobules (where milk is made). Hyperplasia is a term used when there is growth of cells within the ducts and/or lobules of the breast that is not cancer.

Normally, the ducts and lobules are lined by 2 layers of cells. Hyperplasia means that there are more cells than usual, and they are no longer lined up in just the 2 layers.

If growth in the ducts looks much like the normal pattern under the microscope, it may be called usual ductal hyperplasia.

If the growth looks more abnormal, it may be called atypical hyperplasia. This can be either atypical ductal hyperplasia (ADH) or atypical lobular hyperplasia (ALH)

Atypical ductal hyperplasia (ADH)

In ADH, the cells grow in an abnormal pattern and have some (but not all) of the features of ductal carcinoma in-situ (DCIS, which is a pre-cancer). This means that ADH is not yet a pre-cancer, although it is linked to an increased risk of getting breast cancer later on. 

If ADH is found on a needle biopsy, more tissue in that area usually needs to be removed to be sure that nothing more serious, such as DCIS or invasive cancer, is also present nearby. The tissue that is removed is looked at under the microscope, and if nothing more serious is found, no other treatment is needed. 

If ADH is found on an excisional biopsy, usually no more surgery is needed, unless there’s concern that it might not have been removed completely.

Because having ADH increases your risk of breast cancer later on, your doctor may recommend more frequent follow up (with breast exams and imaging tests such as mammograms), as well as taking steps to lower your breast cancer risk, such as making lifestyle changes and taking medicine to help reduce your risk.

Atypical lobular hyperplasia (ALH)

ALH is an abnormal growth of cells within lobules of the breast that is linked with an increased risk of breast cancer.

If ALH is found by a needle biopsy, it isn’t always clear what the best thing to do is. Some doctors might advise removing more of the area around the biopsy site to make sure that there isn’t anything more serious nearby. But many doctors now believe that close follow up with physical exams and imaging tests (like mammograms) is enough in most cases, unless there’s another reason to remove more nearby tissue.

If ALH is found by an excisional biopsy, typically no further treatment is needed.

Because having ALH increases your risk of breast cancer later on, your doctor may recommend more frequent follow up (with breast exams and imaging tests such as mammograms), as well as taking steps to lower your breast cancer risk, such as making lifestyle changes and taking medicine to help reduce your risk. 

Benign (non-cancerous) breast changes

  • Usual ductal hyperplasia
  • Adenosis
  • Sclerosing adenosis
  • Radial scar, complex
  • Sclerosing lesion
  • Papillomatosis
  • Papilloma
  • Apocrine metaplasia
  • Cysts
  • Columnar cell change
  • Collagenous spherulosis
  • Duct ectasia
  • Fibrocystic changes
  • Flat epithelial atypia
  • Columnar alteration with prominent apical snouts and secretions (CAPSS) 

All of these are benign (non-cancerous) changes that the pathologist might see when looking at the biopsy specimens. They aren’t likely to be important if they’re seen on a biopsy sample that also contains atypical ductal or lobular hyperplasia. 

Microcalcifications or calcifications 

Microcalcifications or calcifications are small calcium deposits that can be found in both non-cancerous and cancerous breast lesions. They can be seen both on mammograms and under the microscope.

Because certain calcifications can be found in areas containing cancer, their presence on a mammogram may lead to a biopsy of the area. Once the biopsy is done, the pathologist looks at the tissue removed to be sure that it contains calcifications. If the calcifications are there, the treating physician knows that the biopsy sampled the correct area (the abnormal area seen on the mammogram). 


E-cadherin is a test that might be used to help determine if the hyperplasia is ductal or lobular. (The cells in atypical lobular hyperplasia are usually negative for E-cadherin.) If your report does not mention E-cadherin, it means that this test wasn’t needed to figure out which type of hyperplasia you have. 

Other lab tests that might be done on breast samples

  • High molecular weight cytokeratin (HMWCK)
  • CK903
  • CK5/6
  • p63
  • Muscle specific actin
  • Smooth muscle myosin heavy chain
  • Calponin
  • Keratin 

These are special tests that are sometimes used to help diagnose different types of breast lesions. Whether your report does or does not mention these tests has no bearing on the accuracy of your diagnosis. 

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 editors and translators with extensive experience in medical writing.

Last Revised: July 7, 2023

American Cancer Society Emails

Sign up to stay up-to-date with news, valuable information, and ways to get involved with the American Cancer Society.