Adenosis of the Breast
Adenosis is a benign (non-cancerous) breast condition in which the lobules (milk-producing glands) are enlarged, and there are more glands than usual. Adenosis is often found in biopsy samples of women who have fibrocystic changes in their breasts.
There are many other names for this condition, including aggregate adenosis, tumoral adenosis, or adenosis tumor. Even though some of these terms contain the term tumor, adenosis is not breast cancer.
Sclerosing adenosis is a special type of adenosis in which the enlarged lobules are distorted by scar-like tissue. This type may cause breast pain.
Diagnosis of breast adenosis
If many enlarged lobules are close to one another, they may be large enough to be felt as a breast lump. In cases like this, a breast exam may not be enough to tell if the lump is adenosis or something else (such as breast cancer).
Calcifications (mineral deposits) can form in adenosis (including sclerosing adenosis), as well as in breast cancers. These can show up on mammograms, which can make it hard to tell these conditions apart.
Because of these uncertainties, a breast biopsy is usually needed to know if the breast change is caused by adenosis or cancer. (In a biopsy, small pieces of breast tissue are removed and checked under a microscope.)
Treatment of adenosis
Adenosis doesn't usually need to be treated, unless it's causing bothersome symptoms.
How does adenosis affect your risk for breast cancer?
Most types of adenosis are not thought to increase breast cancer risk, although some studies have found that women with sclerosing adenosis have a slightly higher risk of breast cancer.
- Written by
- References
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.
Collins LC, Schnitt SJ. Chapter 9: Pathology of benign breast disorders. In: Harris JR, Lippman ME, Morrow M, Osborne CK, eds. Diseases of the Breast. 5th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2014.
Guray M, Sahin AA. Benign breast diseases: Classification, diagnosis, and management. Oncologist. 2006;11;435-449.
Orr B, Kelley JL. Benign breast diseases: Evaluation and management. Clin Obstet Gynecol. 2016;59(4):710-726.
Sabel MS. Overview of benign breast disease. UpToDate. 2021. Accessed at https://www.uptodate.com/contents/overview-of-benign-breast-disease on October 28, 2021.
Santen RJ, Mansel R. Benign breast disorders. N Engl J Med. 2005;353:275-285.
Visscher DW, Nassar A, Degnim AC, et al. Sclerosing adenosis and risk of breast cancer. Breast Cancer Res Treat. 2014;144:205-212.
Last Revised: January 25, 2022
American Cancer Society medical information is copyrighted material. For reprint requests, please see our Content Usage Policy.
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.