ConditionWomen's & pregnancy health
Sclerosing Adenosis
Sclerosing adenosis is a benign (noncancerous) breast condition in which the milk-producing lobules grow larger and contain more glands than usual, surrounded by scar-like fibrous tissue. It is often found on a biopsy done for calcifications or a lump on a mammogram, because it can look like cancer on imaging. It is not cancer and does not turn into cancer, but it slightly raises future breast cancer risk, so regular screening continues.
Also called: Sclerosing adenosis of the breast, adenosis of the breast, adenosis tumor (when it forms a lump)
At a glance
- What it is
- Benign overgrowth of breast lobules with fibrous tissue, a type of proliferative breast disease without atypia.
- How it is found
- Usually on a mammogram (calcifications or distortion) followed by a needle biopsy; sometimes as a lump.
- Symptoms
- Often none; sometimes a firm lump or breast pain.
- Cancer risk
- Not cancer; slightly raises long-term breast cancer risk (about 1.5 to 2 times average).
- Treatment
- None needed if the biopsy is clearly benign and matches the imaging; continue routine screening.
When to get help
See a doctor within a day or two
- A new hard or fixed breast lump, skin dimpling, a pulled-in nipple, or bloody nipple discharge
- Red, swollen, warm breast skin that looks like orange peel
Book a routine appointment
- A biopsy report that says sclerosing adenosis: review whether the result matches the imaging and what follow-up is planned
- A lump in the area of known sclerosing adenosis that grows or changes
- Ongoing breast pain in one spot that does not follow your cycle
What is sclerosing adenosis?
The breast is made up of 15 to 20 lobes, each containing many small lobules where milk is made, connected by ducts. Adenosis means enlarged lobules containing more glands than normal. Sclerosing means the glands are squeezed and distorted by fibrous, scar-like tissue.
Under the microscope, the crowded, compressed glands with surrounding fibrosis can look similar to invasive cancer. Pathologists use special stains to confirm the normal two-layer structure of the glands (with an outer myoepithelial layer), which cancer lacks.
Sclerosing adenosis is common, especially in women aged 30 to 50, and is often found alongside other benign changes such as fibrocystic breast changes, papillomas and radial scars.
Symptoms
Most people have no symptoms. When present:
- A firm or hard, sometimes slightly tender lump, called an adenosis tumor
- Breast pain or tenderness, sometimes linked to the menstrual cycle
- Lumpiness in one area
It does not cause nipple discharge, skin changes or nipple retraction. Those need prompt evaluation. Learn more about the causes of a breast lump.
How sclerosing adenosis is diagnosed
Imaging
On a mammogram, sclerosing adenosis can show up as:
- Clusters of tiny calcium deposits (microcalcifications)
- A mass with an irregular or indistinct edge
- Architectural distortion, where the normal tissue pattern looks pulled
These features overlap with cancer, so the radiologist usually gives a BI-RADS 4 (suspicious) result and recommends a biopsy. Ultrasound and MRI may also show a mass or enhancing area.
Biopsy
A core needle biopsy, guided by mammogram (stereotactic), ultrasound or MRI, removes small tissue samples through a hollow needle under local anesthetic. The pathologist confirms sclerosing adenosis and looks for any atypical cells or cancer.
The key step is radiology-pathology concordance: the radiologist and pathologist agree that the benign result fully explains what was seen on imaging. If it does not, for example a highly suspicious mass with a benign biopsy, a repeat biopsy or surgical excision is done.
Is sclerosing adenosis cancer?
No. Sclerosing adenosis is benign and is not considered a precancerous lesion that turns into cancer. However, it belongs to a group called proliferative breast disease without atypia, which is associated with a modest increase in future breast cancer risk in either breast.
| Benign category | Examples | Approximate relative risk of breast cancer |
|---|---|---|
| Nonproliferative | Simple cysts, mild hyperplasia, most fibrocystic changes | No meaningful increase |
| Proliferative without atypia | Sclerosing adenosis, usual ductal hyperplasia, papillomas, radial scar | About 1.5 to 2 times |
| Atypical hyperplasia | Atypical ductal or lobular hyperplasia | About 4 times |
A relative risk of 1.5 to 2 means the absolute risk rises only modestly. For most people, it does not change screening recommendations, but it is factored into risk calculators along with age and family history.
Occasionally, cancer or atypia is found within or next to an area of sclerosing adenosis. That is a separate diagnosis and is treated on its own terms.
Sclerosing adenosis vs other benign breast lumps
| Condition | Typical features |
|---|---|
| Sclerosing adenosis | Calcifications or irregular mass on mammogram; firm lump in some |
| Fibroadenoma | Smooth, rubbery, mobile lump in younger women; well-defined on ultrasound |
| Breast cyst | Fluid-filled, often tender, fluctuates with cycle; clear on ultrasound |
| Fat necrosis | Firm lump after injury or surgery |
Treatment and follow-up
- No treatment is needed for sclerosing adenosis confirmed on a concordant core biopsy.
- Surgical excision is considered if the biopsy does not match the imaging, if atypia is found, or if a lump is large, growing or painful.
- Follow-up imaging: some centers repeat imaging at 6 to 12 months after a benign biopsy; others return you to routine screening.
- Routine screening mammograms continue as recommended for your age and risk.
- Breast pain can be eased with a well-fitting supportive bra and NSAIDs at the label dose.
Lowering overall breast cancer risk
Factors you can influence include limiting alcohol, staying physically active, keeping a healthy weight after menopause and discussing the risks of combined hormone therapy. If you also have a strong family history, ask about a formal risk assessment, as additional screening such as MRI may be recommended.
Frequently asked questions
Is sclerosing adenosis cancer?
No. Sclerosing adenosis is a benign breast condition. It can look like cancer on a mammogram and under the microscope, which is why it is often biopsied, but it does not spread and does not become cancer itself.
Does sclerosing adenosis increase breast cancer risk?
Slightly. It is a proliferative breast change without atypia, which raises lifetime breast cancer risk to about 1.5 to 2 times that of someone without it. The increase is modest, and most people continue regular screening rather than needing extra tests.
Does sclerosing adenosis need to be removed?
Usually not. If a core needle biopsy shows sclerosing adenosis and this fully explains the mammogram or ultrasound findings, no surgery is needed. Excision is recommended if the results do not match, if atypical cells are found, or if a lump is growing or bothersome.
Can sclerosing adenosis cause breast pain?
Yes, some people have breast tenderness or pain, sometimes varying with the menstrual cycle. Many have no symptoms at all. Persistent pain in one spot should still be checked, and a supportive bra and over-the-counter pain relievers usually help.
Sources
This guide was written from current patient and clinical guidance, including:
- American Cancer Society: Adenosis of the Breast
- National Comprehensive Cancer Network (NCCN): Breast Cancer Screening and Diagnosis Guidelines
- American College of Radiology: BI-RADS Atlas
- Johns Hopkins Medicine: Benign breast diseases
- National Cancer Institute: Understanding Breast Changes and Conditions