Normal and Abnormal Mammogram Images

Many people schedule their routine mammograms, but are you familiar with the findings radiologists look for on these images? How can you tell the difference between normal breast tissue, fibrocystic tissue, and breast cancer in these pictures?

On your mammogram report, you may read about some common changes such as dense breasts, calcifications, or even a mass. In addition, you will see a number assigned to something called a BiRADS report. What do these findings mean and what do they look like on images?


Normal Breast Tissue on a Mammogram

Normal Fatty Breast Tissue
National Cancer Institute

Mammograms help with early detection of and screening for breast cancer. The black areas correspond to normal fatty tissue, and white areas are denser breast tissue with ducts and lobes. Breast masses often appear white because they are denser than other features in the breast.

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. 

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.

Breast cancer screening guidelines vary depending on the organization making the recommendations. The best choice for you is that which you and your doctor decide upon based on your specific risk factors and wishes.

Organization Frequency Age
American College of Obstetrics and Gynecology Yearly 40+
American Cancer Society Yearly 45-54
U.S. Preventive Services Task Force Every other year 50-74

Having a baseline mammogram regardless of the frequency of your mammograms is very helpful. 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 dense tissue.

Keep in mind that these recommendations are for women who are asymptomatic (have no symptoms at all that could suggest breast cancer) and have an average risk of developing the disease.


Normal Dense Breast Tissue on a Mammogram

Normal Dense Breast Tissue
National Cancer Institute

Young women, especially those who have not had children, usually have dense and rather firm breast tissue, which makes a mammographic image difficult to read. Mammography equipment can be adjusted to image dense or fatty tissue, but mammograms are considered most accurate on fatty tissue and older women.

This mammogram image shows two mammograms of normal, dense breasts. The dark areas are fatty tissue, the light areas are denser tissue that contains ducts, lobes, and other features. Lighter areas of a mammogram reveal breast tissue that may be glandular (part of the milk system) or breast masses.

Because fatty breasts are easier for a mammogram to see through, dense breast tissue can sometimes hide outlines of areas that need closer study. If a particular area needs a better image, a breast ultrasound is usually the next step.

Having dense breasts is not abnormal and just means you have less fat in your breasts. The term "dense breasts" is based on their appearance on a mammogram and not what they feel like. Breasts can feel firm but not be dense, and vice versa. Women with dense breasts do, however, have a slightly higher risk of developing breast cancer.

For young women with a strong family history of breast cancer, or those known to have genetic mutations which increase risk, a breast MRI can sometimes provide much better images of dense breast tissue.


Breast Calcifications on a Mammogram

Breast Calcifications on a Mammogram
National Cancer Institute

In this mammogram image, the dark areas are normal fatty breast tissue and the lighter areas are denser tissue. The whiter spots are calcifications, which are indicated by the red arrows. The breast calcifications are in ductal patterns, as calcification occurs along the milk ducts of the breast. This is considered an abnormal mammogram, but not necessarily cancerous.

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

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

In this case, the woman was advised to have a follow-up mammogram in three months for comparison. If a woman has a lump associated with calcifications, however, immediate further testing is needed.

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.


Fibrocystic Breast Tissue on a Mammogram

Fibrocystic Breast Tissue
National Cancer Institute

fibroadenoma or cyst 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 mass. This mammogram shows thickened areas that are typical of fibrocystic changes. You can also see 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 a problem, visit your doctor for help.

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 on ultrasound.


Breast Tumor on a Mammogram

Breast Cancer Tumor on Mammogram
National Cancer Institute

This mammogram shows dark areas of normal fatty breast tissue. Lighter areas are dense breast tissue that includes ducts and lobes. The whitest area is the densest, showing a cancerous tumor, indicated by a red arrow in the lower right corner of the image.

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.

A 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.

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.

It's also important to note that a mammogram may appear normal even if a cancer is present. Roughly 20 percent 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.


Breast Implant on a Mammogram

Mammogram With Implants

Pam Stephan

This mammogram shows two views of a breast following a mastectomy and reconstruction with a silicone breast implant. This woman had been successfully treated for a type of breast cancer called invasive ductal carcinoma. Mammograms taken after a diagnosis of breast cancer are important screening tests. There is no evidence of breast cancer in these images.

Mammograms can be performed on breast implants if less compression is used than what is required on natural breast tissue. 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.

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.


Mammogram and MRI Image Comparisons

Mammogram and MRI Breast Images Comparison
National Cancer Institute

Mammograms are the primary screening tool used for breast health, but for greater detail of a particular area, or to screen women at high risk who have dense breast tissue, an MRI (magnetic resonance imaging) can capture a higher contrast, detailed image.

Breast MRIs are 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 but primarily used to diagnose abnormal tissue or screen those who are at a very high risk of developing breast cancer. 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.

If a mammogram has shown a breast mass that seems worrisome, an MRI or ultrasound can provide more accurate information. If the MRI confirms that a mass looks cancerous, the next step is a breast biopsy.


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 number referred to as the BIRADS number. BIRADS 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 a number between 1 and 5.

  • 1 refers to a normal mammogram
  • 2 is benign or negative
  • 3 is probably benign
  • 4 is possibly malignant
  • 5 is malignant, though there are conditions that can mimic cancer on a mammogram
A Word From Verywell

Mammograms can be helpful alongside other tests 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.

Adding some confusion to this is the varying recommendations by organizations as well as differing opinions of individual doctors. In the end, you need to be your own advocate in your health care. Learn about the limitations of a mammogram. If you are concerned due to a strong family history of breast cancer, talk to your doctor about the option of having a breast MRI. If you develop a lump, a breast ultrasound is sometimes more helpful in making a diagnosis.

While all of this is important, the best "treatment" is to prevent cancer from occurring in the first place. While many cancers arise for no apparent reason, and we know that many extremely healthy women develop breast cancer, some things can lower your risk.

Eating a healthy diet rich in fruits and vegetables is a start. Engaging in regular exercise is also a must. Studies also suggest that women with low vitamin D levels may have an increased risk. At your next appointment, ask your doctor to check your vitamin D level. If it is low she can help you find ways to raise it, whether that means spending a little more time in the sun or taking a vitamin D supplement.

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