Normal and Abnormal Mammogram Images

What shading may (or may not) indicate

A mammogram image has a black background and shows the breast in variations of gray and white. Generally speaking, the denser the tissue, the whiter it appears. This may include normal tissue and glands, as well as areas of benign breast changes (e.g., fibroadenomas) and disease (breast cancer). Fat and other less-dense tissue renders gray on a mammogram image.

A radiologist will consider all of this when reviewing your mammogram images, but it's important to note that what's normal for one woman may not be for the next. For example, women with naturally dense breasts will have more white on their mammogram images, even if there is no disease present.

The following are just a few examples of the variety of mammogram images a radiologist may encounter and how they are interpreted. Your mammogram report will detail the radiologist's opinion about what they reviewed (possibly including notes about things like breast density, calcifications, or a mass), as well as BI-RADS number, which gives a sense of the extent to which the mammogram is considered normal or of concern.

Normal Breast Tissue

Normal Fatty Breast Tissue
National Cancer Institute

This image is a mammogram of a normal fatty breast, typical of older women, that does not have a lot of dense tissue. A mammogram searching for abnormal lesions, benign lumps, or breast cancer is more accurate when performed on women with non-dense breasts such as these.

The gray areas correspond to normal fatty tissue, while the white areas are normal breast tissue with ducts and lobes. While breast masses also appear white on a mammogram, the color is typically more concentrated because they are denser than other features of a normal breast, like those seen here.

Most women will have their first mammogram around the age of 40, and this can serve as a good baseline from which to compare your images in the future. Women with breast cancer risk factors may start screening earlier.

Having a baseline mammogram regardless of the frequency of your mammograms is very helpful in establishing what normal is for you. Over time, a woman's breasts can change, especially after childbirth, following a breast biopsy, or with breast implants. It is not uncommon to get benign lumps, cysts, masses, calcifications, or denser tissue.

Normal Dense Breast Tissue

Normal Dense Breast Tissue
National Cancer Institute

This image shows two mammograms of normal, dense breasts. As with the first image, the dark areas are fatty tissue, and the light areas are denser tissue that contains ducts, lobes, and other features. Compare these images and you can see the differences in density in what are both normal breasts.

Young women, especially those who have not had children, usually have dense and rather firm breast tissue. Mammogram images such as these can be difficult for a radiologist to read because there is less differentiation between normal and possibly abnormal tissue, essentially hiding areas that warrant closer study.

Mammography equipment can be adjusted to image dense breasts, but that may not be enough to solve the problem. If a particular area needs a better image, a breast ultrasound is usually the next step. A breast MRI may be recommended for young women with a strong family history of breast cancer or those known to have genetic mutations that increase risk (see below).

Dense breasts are identified as such based on their appearance on a mammogram—not what they feel like. Having dense breasts is not abnormal. It just means you have less fat in your breasts than is typical. However, women with dense breasts do have a slightly higher risk of developing breast cancer.

Breast Calcifications

Breast Calcifications on a Mammogram
National Cancer Institute

Here, the lighter white areas show denser tissues, but the more concentrated white spots are calcifications.

Microcalcifications are tiny bits of calcium that may show up in clusters or in patterns (like circles) along the milk ducts and are associated with extra cell activity in breast tissue. Usually, the extra cell growth is not cancerous. Sometimes, however, tight clusters of microcalcifications can be an early warning sign of precancerous cells. Scattered microcalcifications are usually a sign of benign breast tissue.

The pattern and shape of microcalcifications can also give radiologists clues about whether cancer may be present. Linear, rod-like calcifications raise suspicion of underlying breast cancer, whereas popcorn, eggshell, and rim-like calcifications are usually benign.

In this mammogram image, the breast calcifications are in ductal patterns. This is considered an abnormal mammogram, but not necessarily one that's indicative of cancer. In this case, the woman was advised to have a follow-up mammogram in three months for comparison. If the woman had a lump associated with these calcifications, however, immediate further testing would have been needed.

Macrocalcifications (large calcifications) are larger bits of calcium due to the normal process of aging in the breasts. They are found in roughly half of women over the age of 50, and unlike microcalcifications, are not usually a sign of cancer.

Fibrocystic Breast Tissue

Fibrocystic Breast Tissue
National Cancer Institute

Fibroadenomas and cysts are benign breast masses that can appear in fibrocystic breast tissue. These can appear alone or in groups and appear on mammograms as a dense (white) mass.

This mammogram highlights thickened areas that are typical of fibrocystic changes. You can also identify some ducts by the patterns they form.

Normal fibrocystic changes in the breast can be affected by monthly hormonal fluctuations that may taper off in menopause. About half of all women experience fibrocystic changes in their breasts, especially during their fertile years.

Fibrocystic changes in the breast are usually not a sign of disease and do not require treatment. These changes can sometimes cause breast pain and lumpiness, so if this becomes concerning, see your doctor.

If an abnormality is thought to be a cyst, a breast ultrasound is usually done to confirm that it is a cyst rather than a solid nodule. With ultrasound guidance, a radiologist can place a needle in the cyst to drain it and the cyst will disappear.

Breast Tumor

Breast Cancer Tumor on Mammogram
National Cancer Institute

As with the others, this mammogram shows both normal fatty tissue (dark) and lighter areas of denser breast tissue. What's concerning here is the whitest area on the bottom right, which shows a cancerous tumor.

A cancerous tumor in the breast is composed of a mass of cancer cells that are growing in an abnormal, uncontrolled way. The tumor may invade surrounding tissue, or it may shed cells into the bloodstream or lymph system. If the tumor cells migrate beyond the original site and spread to other parts of the body, it is considered metastatic breast cancer.

It's important to note that even if a change looks very much like cancer on mammogram, there are some benign breast changes that mimic breast cancer. When this occurs, further imaging—and most often, a biopsy—are necessary to know whether it is truly cancer or not.

Likewise, a mammogram may appear normal even if a cancer is present. Roughly 20% of breast cancers are not seen on a screening mammogram, and this number may be higher for women who have very dense breasts. In addition, some types of breast cancer, such as inflammatory breast cancer and Paget's disease of the breast, do not usually result in a mass and can easily be overlooked on a mammogram.

A confirmed breast tumor usually requires treatment by surgery and may require chemotherapy, radiation, targeted biological therapy, and/or hormonal therapy. When a breast tumor is found in an early stage of cancer, it is more likely to be successfully treated to prevent its spread or recurrence.

Breast Implant

Mammogram With Implants

Pam Stephan

This mammogram shows two views of a breast following a mastectomy and reconstruction with a silicone breast implant. (Mammograms can be performed on breast implants if less compression is used than what is required with natural breast tissue.) This woman had been successfully treated for a type of breast cancer called invasive ductal carcinoma.

In both views of this breast reconstruction, the implant appears as a light, smooth-sided area. This implant is inserted into a pocket of the chest wall. The chest wall muscle appears as the medium-dark area just outside the implant.

Mammograms taken after a diagnosis of breast cancer are important screening tests. There is no evidence of breast cancer in these images.

Note that the overhead view, called the cranial-caudal view, shows a smaller area than the diagonal view, called the mediolateral view. Having these two views is very helpful for doctors to determine breast health.

Your Mammogram Report

Your mammogram report will describe findings such as those noted above. If you are unsure of what any findings mean, talk to your doctor.

In addition to noting any findings, you will see a BI-RADS number. BI-RADS stands for Breast Imaging Reporting and Data System, and the number is a classification of the likelihood your mammogram is normal or shows cancer.

If you have not had a biopsy, you will be assigned a number between 0 and 5, with 0 indicating that the mammogram didn't provide enough information to make a clear call and 6 indicating a proven malignancy.

Mammogram and MRI Image Comparisons

Mammogram and MRI Breast Images Comparison
National Cancer Institute

Mammograms are the primary screening tool used for breast health. Breast magnetic resonance imaging (MRI) is much more expensive than mammograms, and the equipment is not as widely available. For this reason, MRI technology is not used for routine breast screening.

However, breast MRI has its place. Because it can capture an image that is higher contrast and more detailed than a mammogram, it may be used for women who are at high risk for breast cancer or have dense breasts, or when a mammogram reveals an area that needs further examination. It is also often used, especially in younger women, to monitor the other breast for the development of breast cancer if a woman has had a mastectomy on one side.

These two side-by-side comparisons show mammography on the left and an MRI on the right. The MRI image illustrates the deeper level of detail, which is extremely helpful to confirm a diagnosis.

A Word From Verywell

Mammogram images can be helpful alongside other tests results in the early diagnosis of breast cancer and may find cancers which are not yet palpable. At the same time, a concern of overdiagnosis has been raised in recent years. For example, the presence of microcalcifications, while sometimes alerting your physician to underlying cancer, has many benign causes as well. Keep the limitations of mammograms in mind and talk with your doctor about additional testing if you are concerned about their accuracy or your risk.

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