The Who, What, Where, When and Sometimes, Why.

Findings on a Mammogram

Mammography uses X-rays to create images of the breast. These images are called mammograms.

Learn more about mammograms.

Learn about getting a mammogram.

Mammography images

Like other X-ray images, mammograms appear in shades of black, gray and white, depending on the density of the tissue (see images below).

Very dense tissue, like bone, shows up as white on an X-ray. Fat looks dark gray on an X-ray.

Breast cancer and some benign breast conditions are denser than fat and appear a lighter shade of gray or white on a mammogram.   

Dense breast tissue

Dense breast tissue can look light gray or white on a mammogram. This can make abnormal findings hard to see on a mammogram.

Younger women tend to have dense breast tissue, so their mammograms can be harder to read than the mammograms of older women.

After menopause, breast density decreases, making mammograms easier to read.

The mammograms below show a range of breast density. Some breasts are mostly fat (fatty breasts) and some breasts are mostly breast tissue (dense breasts).

Fatty breast

Fatty breast

Some breast density

Some breast density

More breast density

More breast density

Dense breast

Dense breast

Breast density after menopause

Breast density decreases after menopause. This is true for women who go through natural menopause and younger women who are in menopause after surgery to remove the ovaries (oophorectomy).

For women who use menopausal hormone therapy (MHT), breast density may not decrease until they stop using MHT.

Breast density and breast cancer risk

Women with dense breasts (as seen on a mammogram) have a higher risk of breast cancer than women with fatty breasts [22-23].

Learn more about breast density and breast cancer risk.


Komen Perspectives

Read our perspective on breast density and breast cancer risk.*

Screening tools under study for women with dense breasts

Dense breast tissue can make abnormal findings hard to see on a mammogram.

There are no special recommendations or breast cancer screening guidelines for women with dense breasts.

Some tools are under study for breast cancer screening in women with dense breasts.

Some data suggest 3D mammography (breast tomosynthesis) may find more breast cancers in women with dense breasts compared to 2D mammography [24].

Breast ultrasound and breast MRI (each combined with mammography) are being studied to learn whether they improve detection in women with dense breasts compared to mammography alone.

Breast density legislation

Many states in the U.S. have laws requiring health care providers to notify (send a letter to) women found to have dense breasts on a mammogram. In 2019, the U.S. Congress passed national breast density legislation. The Food and Drug Administration (FDA), which regulates mammography centers, is developing regulations for notification.

Although this may seem helpful, there are no special recommendations or screening guidelines for women with dense breasts. However, your provider may suggest other types of breast imaging.

If you have any concerns about your breast density or your risk of breast cancer, talk with your provider.

Findings on a mammogram

Benign breast conditions (not cancer)

Some common benign breast conditions (such as cysts and fibroadenomas) may show up on mammograms as round or oval patches with distinct borders. 

Learn more about benign breast conditions.

Calcifications and microcalcifications

Calcifications are bits of calcium that can show up on mammograms as small, bright white spots.

Most calcifications are benign (not cancer). However, certain patterns of calcifications are suspicious and need more testing. Tight clusters or lines of tiny calcifications (microcalcifications) can be a sign of breast cancer.

Calcifications are common, especially after age 50 [25]. They may be related to past injury to the breast or mastitis (an infection in the breast) [25].

In women treated for breast cancer in the past, calcifications may be related to past breast surgery or radiation therapy [25].

Ductal carcinoma in situ (DCIS)

Ductal carcinoma in situ (DCIS) is a non-invasive breast cancer.

On a mammogram, DCIS usually looks like a cluster of microcalcifications. It can be hard to know from a mammogram image whether the cluster is DCIS or invasive breast cancer. (A cluster of microcalcifications can also be a benign finding on a mammogram. This means it’s not cancer.)

Learn about follow-up after an abnormal mammogram.

Learn more about DCIS.

Invasive breast cancer

Invasive breast cancer can appear as a white patch or mass on a mammogram.

The tumor cells don’t stay within the clear borders of the mass, but instead invade the nearby breast tissue. The outer edges of these cells look fuzzy or spiky (called spiculated).

Learn about follow-up after an abnormal mammogram.

Mammography results

When to expect mammography results

Some centers give you the results of your mammogram at the time of your screening. With others, it may take up to 2 weeks to get your results.

If you don’t get your results within 2 weeks, contact your health care provider or the mammography center.

Don’t assume the results were normal because you didn’t get a report. Follow-up to get your results.

Breast Imaging Reporting and Data System

Most mammography centers report the results of mammograms using the Breast Imaging Reporting and Data System (BI-RADS®).

BI-RADS® was developed by the American College of Radiology to provide a standard way to describe the findings on mammograms (with categories numbered 0 to 6).

Assessment is complete

BI-RADS® category

What this means

1: Negative

No evidence of cancer on the mammogram.

Nothing suspicious or worrisome was seen on the mammogram.

2: Benign finding(s)

No evidence of cancer on the mammogram.

This also a negative result, but to be complete it’s noted there are findings that appear benign (not suspicious), such as a cyst.

3: Probably benign finding – initial short-interval follow-up suggested

More than 98 percent of these will NOT be cancer, but to be sure, follow-up exams are needed (usually at 6 months and then afterwards as needed).

4: Suspicious abnormality – biopsy should be considered

The findings do not definitely look like cancer, but could be cancer.

Some, but not all, radiologists may divide this category further into 4A, 4B and 4C based on how suspicious the findings are for cancer (4A look the least like cancer).

5: Highly suggestive of malignancy – appropriate action should be taken

The finding has a high chance (95 percent or more) of being cancer.

6: Known biopsy-proven malignancy – appropriate action should be taken

This category is only for findings already confirmed as cancer with a biopsy.

Assessment is incomplete

BI-RADS® category

What this means

0: Need additional imaging evaluation and/or prior mammograms

More information is needed to know whether a finding is abnormal.

Adapted from American College of Radiology’s BI-RADS® – Mammography, Fifth Edition, 2013 and American Cancer Society materials [26-27] with permission of the American College of Radiology.

*Please note, the information provided within Komen Perspectives articles is only current as of the date of posting. Therefore, some information may be out of date.

Updated 03/08/21