Breast Cancer Information/Diagnosis and Testing

Fibroglandular Density: What It Means for Mammograms

Medically reviewed by Maybell Nieves, M.D.

Written by Anastasia Climan, RDN, CDN

Posted on September 1, 2026

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Key Takeaways

Mammogram reports can include confusing terms like 'fibroglandular density,' which describes whether breasts are made up of more dense tissue or fatty tissue, and it is not a sign of cancer.

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Mammogram results can be unsettling, even if they don’t show any tumors in your breasts. If you don’t recognize the words on your report, you may wonder if something’s wrong.

“There are ‘scattered areas of fibroglandular density,’” shared a MyBCTeam member. “I’m not sure what some of this means, but it says there’s no malignancy (cancer) found. I can’t help but be a little worried.”

Let’s dive into what “fibroglandular” means and how fibroglandular density can affect your mammogram results.

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What Is Fibroglandular Density?

Fibroglandular density describes whether your breasts are dense (thick) or not. Fibroglandular tissue is the way radiologists describe the normal type of breast tissue. Your genetics and other factors play a role in your breast density. It’s not cancer.

Having more fibroglandular density may mean you need follow-up testing to screen for breast cancer, but not always. Your healthcare provider will consider breast density with other risk factors before making screening recommendations.

Knowing what tissue types breasts are made of makes it easier to understand the term “fibroglandular.”

Types of Breast Tissue

There are three general types of breast tissue: fatty, glandular, and fibrous connective tissue.

Fatty tissue is the opposite of dense. On a mammogram, fatty tissue appears see-through or dark, fading into the background of the image, making it easier to spot white areas that indicate cancer or suspicious lumps.

Fibrous connective tissue and glandular tissue are both dense. They appear as white areas on a mammogram, just like cancerous tumors.

“Fibroglandular” includes both these types of dense tissue. Glandular tissue is the milk ducts and glands in the breast. Collagen (a protein) and cells called fibroblasts make up most of the breasts’ fibrous connective tissue.

Fibrous tissue provides structure and support to the breasts. You can also find similar connective tissues in other areas like the ligaments, tendons, skin, and parts of the eye.

How To Know Your Breast Density

Your mammogram report will say if you have dense breasts or not. The U.S. Food and Drug Administration (FDA) requires doctors to include this information. You can find it in your Breast Imaging Reporting and Data System, the standard mammogram results report.

Dense breasts are more common in those who haven’t gone through menopause. After menopause, hormone replacement therapy is linked to an increased chance of dense breasts. Being lean and having a low body fat level also increases the chance of dense breasts.

“I was thinking about the dense breast tissue agenda, and I find it maddening that we have to have a law in place to tell us if we have dense breasts. What the heck is this?”

— A MyBCTeam member

The size of your breasts or how firm they feel has nothing to do with breast density. A mammogram is the only way to know how much fibroglandular tissue you have.

Fibroglandular Density Grades on a Mammogram

Your doctor will give a “grade” based on your breast density. The four grades for breast density include:

A — Breasts have low density and are mostly fatty tissue.
B — Breasts are mostly fatty with scattered areas of fibroglandular density.
C — There’s more dense tissue than fatty tissue, spread evenly throughout (heterogeneously dense).
D — Breast tissue is extremely dense with little fatty tissue.

Most people fall somewhere in the middle. About 80 percent of breasts are grade B or C. The remaining 20 percent are split evenly (10 percent each) between grades A and D.

Should You Have Extra Screening?

Most people would rather avoid unnecessary medical testing. However, a follow-up or supplemental screening can give you peace of mind if high fibroglandular density leaves you with any questions about your mammogram results.

You’ll need to weigh the pros and cons of extra screening with your healthcare provider. Even if you have high fibroglandular density, screening too much can lead to false positives, added worry, and unnecessary biopsies.

A false positive is a mistake in your test results. It mistakenly shows that you have a suspicious mass when you don’t.

False positives are more likely to happen with breast ultrasounds and magnetic resonance imaging (MRI) tests. Although they can help find small cancers in dense breasts, these tests can also be expensive and aren’t always covered by insurance. For this reason, the screening decisions must be individualized for each case.

Discuss Mammogram Results With Your Provider

Making healthy lifestyle choices and keeping an open dialogue with your healthcare team is the best way to manage your risks.

Always discuss your mammogram results with your healthcare provider. If there’s anything that you don’t understand, don’t hesitate to ask questions and learn more about what your report means.

Is Fibroglandular Density Dangerous?

Fibroglandular tissue itself isn’t harmful, but it can prevent cancerous cells from being found during routine breast cancer screening. This puts you at risk of delaying the early detection of breast cancer.

“I had a mammo and ultrasound. Both were OK, but I have dense breasts. It’s impossible not to think daily about breast cancer maybe returning.”

— A MyBCTeam member

There’s some evidence that high breast density is associated with a higher breast cancer risk. If you have dense breasts, don’t skip your regular mammograms. Mammograms are still helpful at spotting breast cancer, even in dense breasts.

In addition, pay attention to the look and feel of your breasts. Report any changes to your healthcare provider. They can decide if you need more testing.

Screening Options for Dense Breasts

It’s essential to know your medical history and risk factors. If you switch providers, you can explain that you have high fibroglandular density. This information can help them choose the best screening method for you.

3D Mammogram

Three-dimensional mammograms are a better option for breasts with high fibroglandular density. Unlike 2D mammograms, 3D mammogram images let the radiologist look beyond the dense areas to check for cancer.

Unfortunately, 3D mammography (also known as digital breast tomosynthesis) isn’t available everywhere. It also requires more radiation, which may pose an extra risk of cancer in some cases.

Upcoming Technologies

Newer techniques are on the horizon to improve screening for dense breasts. For instance, an abbreviated breast MRI is a quicker alternative to traditional MRI scans.

Another method, known as contrast-enhanced mammography (CEM), is like a regular mammogram. However, CEM uses a special dye to help highlight cancer cells. Although not yet widely available, research suggests CEM could detect cancer better in dense breasts.