Atypical Hyperplasia

Hyperplasia is an abnormal but non-cancerous pattern of cell growth within the ducts or lobes of the breast. A hyperplastic breast shows a higher number of cells and layers in the ducts and lobules than the normal 2 layers of cells on microscopic examination.

If the arrangement of the cells in the proliferative region appears more or less similar to the normal cell pattern, it is called usual hyperplasia. If the growth pattern is abnormally disorganized, it is called atypical hyperplasia.

Wire-guided (needle) localization: specimen radiograph of breast biopsy (lumpectomy) for atypical ductal hyperplasia (ADH). A metallic clip marks prior biopsy site, needles bracket abnormality. Image Copyright: David Litman / Shutterstock
Wire-guided (needle) localization: specimen radiograph of breast biopsy (lumpectomy) for atypical ductal hyperplasia (ADH). A metallic clip marks prior biopsy site, needles bracket abnormality. Image Copyright: David Litman / Shutterstock

Atypical hyperplasia is thus described as an accumulation of abnormally proliferating cells in the breast. It is not cancer, but can be a pre-cancerous condition, where the abnormal cells causing atypical hyperplasia keep dividing. This may result in non-invasive or invasive breast cancer in the long term.

Women with Atypical Hyperplasia are at Higher Risk of Breast Cancer - Mayo Clinic

Women with a diagnosis of atypical hyperplasia have a higher risk of developing breast cancer in future, than those who do not have the condition. For this reason, intensive breast cancer screening and preventive medications to lower the risk of breast cancer is recommended in these cases. However, it is worth noting that the majority of women with atypical hyperplasia never develop breast cancer in their lifetime.

Signs and Symptoms

Atypical hyperplasia does not cause any signs or symptoms in most cases, though breast changes may be detected on a mammogram.

Types of Atypical Hyperplasia

There are 2 types of atypical hyperplasia – ductal and lobular. This indicates the site of origin of the abnormal cells. ‘Ductal’ means the abnormal cells are present in the duct through which the breast milk travels to reach the nipple. ‘Lobular’ means that the abnormal cell growth is in the lobules, which are the areas in the breast that make milk. While atypical ductal hyperplasia increases the breast cancer risk in the area where it was found, atypical lobular hyperplasia increases the risk that cancer may develop in either breast.

Atypical Ductal Hyperplasia

If the abnormal pattern of cell growth is found to occur within the ducts, it is called atypical ductal hyperplasia. It is not a pre-cancerous condition yet, but is linked to breast cancer risk in the future. The tissue removed for biopsy needs to be thoroughly investigated under a microscope. More tissue may be removed from the surrounding area to confirm the diagnosis. If cancerous changes are not detected, no treatment is necessary. Follow-up breast imaging and examinations must be scheduled as part of screening.

Atypical Lobular Hyperplasia

Atypical lobular hyperplasia occurs within the breast lobules and is linked to an increased risk of breast cancer in the future. Similar to ductal hyperplasia, microscopic examination of tissue reveals the cell growth pattern and based on the results, doctors will decide if more tests are required. Follow up with imaging and physical exams are recommended.

Diagnosis of Atypical Hyperplasia

Atypical hyperplasia is normally detected during a biopsy to study suspicious areas revealed during routine breast examination or by a mammogram. It is usually diagnosed during a breast biopsy performed in order to investigate the abnormal pattern detected on a mammogram. Rarely, it may be discovered during a biopsy performed for an unrelated condition.

Samples of tissue are removed during biopsy and sent to a lab for analysis by a pathologist. These samples are studied under a microscope which reveals the presence or absence of atypical hyperplasia.

In case atypical hyperplasia is diagnosed, a surgical biopsy may be performed to remove the affected breast tissue. Further evaluation via surgery may be recommended by the doctor and this involves removal of a larger tissue sample from the breast and testing it for the presence of cancerous cells. The larger sample is analyzed by the pathologist for any evidence of invasive or non-invasive cancer.


Further Reading

Last Updated: Feb 26, 2019

Susha Cheriyedath

Written by

Susha Cheriyedath

Susha is a scientific communication professional holding a Master's degree in Biochemistry, with expertise in Microbiology, Physiology, Biotechnology, and Nutrition. After a two-year tenure as a lecturer from 2000 to 2002, where she mentored undergraduates studying Biochemistry, she transitioned into editorial roles within scientific publishing. She has accumulated nearly two decades of experience in medical communication, assuming diverse roles in research, writing, editing, and editorial management.


Please use one of the following formats to cite this article in your essay, paper or report:

  • APA

    Cheriyedath, Susha. (2019, February 26). Atypical Hyperplasia. News-Medical. Retrieved on July 19, 2024 from

  • MLA

    Cheriyedath, Susha. "Atypical Hyperplasia". News-Medical. 19 July 2024. <>.

  • Chicago

    Cheriyedath, Susha. "Atypical Hyperplasia". News-Medical. (accessed July 19, 2024).

  • Harvard

    Cheriyedath, Susha. 2019. Atypical Hyperplasia. News-Medical, viewed 19 July 2024,


The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of News Medical.
Post a new comment

While we only use edited and approved content for Azthena answers, it may on occasions provide incorrect responses. Please confirm any data provided with the related suppliers or authors. We do not provide medical advice, if you search for medical information you must always consult a medical professional before acting on any information provided.

Your questions, but not your email details will be shared with OpenAI and retained for 30 days in accordance with their privacy principles.

Please do not ask questions that use sensitive or confidential information.

Read the full Terms & Conditions.

You might also like...
COVID-19 tied to elevated risk of benign prostatic hyperplasia complications