Benign Breast Changes That Mimic Breast Cancer

Breast Cancer Look-Alikes on Exam and Mammogram

Most of us have known someone who had breast cancer despite a normal mammogram. On the flip side, there are benign (not cancerous) breast changes which can mimic breast cancer as well. These breast cancer look-alikes can cause great anxiety and stress, as some benign breast changes not only look like breast cancer on exam, but can do so on mammogram, ultrasound, or even MRI as well. What are some conditions that might be mistaken for breast cancer but are otherwise benign?

A woman holding her breasts while nervous / Stock Photo©Anetlanda 

Let's begin by looking briefly at the symptoms and signs of breast cancer on an exam and on imaging studies.

Breast Cancer Symptoms

Certainly benign and malignant breast lumps can sometimes feel the same, but there are some characteristics that are more common with cancer. These include:

  • A breast lump that feels firm (lumps that feel squishy, like a soft rubber ball, are more likely to be benign)
  • A breast mass that is fixed and can't be moved around under the skin
  • Redness and swelling (symptoms of inflammatory breast cancer)
  • Enlarged lymph nodes under the arm (keep in mind that lymph nodes under the arm (axillary nodes) may become enlarged for many reasons including some viral infections, and scratches or cuts on the hand or arm)

Mammogram Findings With Breast Cancer

As with your clinical exam, it can sometimes be difficult to distinguish between a benign process in the breast and breast cancer. In fact, sometimes these can completely overlap (the purpose of this article). Mammograms are thought to be 60% to 90% sensitive, which means that 60% to 90% of the time if a cancer is present, the mammogram will find it. Mammograms have a specificity of 93%. This means that 93% of the time, something that looks strongly like a cancer on a mammogram will be cancer. This means that 7% of the time when a mammogram strongly suggests cancer, it is something else.

Mammogram findings that suggest cancer include breast calcifications, masses with an irregular shape, and a spiculated mass (the mass has the appearance of tentacles extending outwards from the main mass). Radiologists give a mammogram a number known as the Breast Imaging Reporting and Data System or BI-RADS classification. In this system, a mammogram report is given a number between 1 and 6 describing the likelihood of cancer. A number of 1 means there are no signs of cancer and a number of 5 means the mammogram is highly suggestive of cancer (a number of 6 means cancer and is only given after a biopsy is done).

The average recall rate from a screening mammogram is 9.8%, meaning that almost 10% of women who have a mammogram (and who do not have any symptoms) will be called back to do other studies. Of these women, 12% will need a biopsy done. Of these biopsies, 60% will be benign. In other words, even if you have an abnormal mammogram, and even if follow-up studies recommend you have a biopsy done, you are still more likely to have a benign breast process than cancer.

Breast Ultrasound Findings With Breast Cancer

Breast ultrasound exams are an important supplement when used along with mammograms. They can sometimes distinguish a cyst from a solid mass, and when a cyst is present it can be drained under ultrasound guidance to resolve the problem. Ultrasounds may be used along with mammogram as a screening tool for women with dense breasts as well, but they do have a relatively high false positive rate. This means that they have a relatively high rate of suggesting a cancer even though a cancer is not present.

On an ultrasound, signs that suggest a cancer include an irregular solid mass, irregular margins, and a "non-parallel orientation."

Breast MRI Findings With Breast Cancer

Breast MRIs are usually reserved for women with an elevated risk of developing breast cancer, have already had breast cancer, or as a follow-up study to inconclusive findings on a mammogram, ultrasound, and exam. On an MRI, findings that suggest breast cancer include a mass with spiculated margins, rim enhancement around the mass, or what is known as "washout kinetics." While a spiculated mass on MRI has a relatively high chance of being a cancer, there are benign changes that can mimic even MRI findings.

Breast Biopsy and Cancer

breast biopsy is a definitive test if a cancer is suspected. This can be done as a fine needle aspiration biopsy (usually reserved for breast cysts), core needle biopsy, stereotactic breast biopsy, or open surgical biopsy. If the results of a core biopsy and imaging studies are discordant, a surgical (open) breast biopsy usually follows.

A biopsy can also determine the type of cancer if one is present and the presence of estrogen, progesterone, and HER2 (human epidermal growth factor receptor 2) receptors. As noted above, even for women who have mammogram and ultrasound findings suggestive of cancer, it is still more likely that a biopsy will be benign.

Even with a biopsy, there is still a small chance of both false-positives (appearance under the microscope that looks like cancer but is not) and false-negatives (a benign appearing sample taken on biopsy but with a cancer being present).

So what are the breast conditions that mimic breast cancer on an exam or imaging reports that necessitate a biopsy? There are several we will look at here. Some of these are more common than others, and the conditions below are not listed in order of prevalence.

Breast Cancer Look-Alikes

It might seem like there should be obvious differences between cancerous and noncancerous changes in your breast, but sometimes this can be quite challenging. Even though we worry more about missing a diagnosis of breast cancer, worrying that a benign change is cancer causes considerable anxiety and grief.

In other words, if you have an abnormality that feels like it could be cancer on an exam, or looks like cancer on a mammogram, keep in mind that it may still be benign. It's not until a biopsy is done and the cells looked at under a microscope that doctors can tell you for sure. Conditions that resemble cancer on exam or imaging are listed below. Let's look at each of these a bit closer.

Fat Necrosis

Fat necrosis of the breast literally means "dead fat." Fat necrosis is a fairly common cause of a benign breast lump and can both feel like a cancer on exam and look very much like cancer on a mammogram. It is usually preceded by an injury to the breast from a car accident or sports injury. Areas of fat necrosis also commonly follow surgical procedures such as breast reductions, breast reconstructions, or biopsies or surgeries for breast cancer. Radiation for breast cancer can also cause fat necrosis, raising concern over a possible recurrence.

These lumps usually feel hard and are sometimes tender. There may be discharge from a nipple. Perhaps most frightening of all they often cause skin tethering which results in nipple retraction or inversion; a commonly known sign of breast cancer. On a mammogram, they can have an irregular shape with a spikey border and microcalcifications. Breast fat necrosis can also appear much like cancer on a PET scan. A biopsy may need to be done to confirm the diagnosis.

Radial Scar

Radial scars are a star-shaped breast masses that are often benign but may be precancerous. Radial scars do not cause breast lumps but may cause breast pain. On mammogram, large radial scars can appear star-like with spikey borders. They are fairly uncommon and occur most often in women between the ages of 40 and 60. They can be caused by inflammation, breast surgery, or hormonal changes.

A biopsy is almost always needed, but even under the microscope radial scars can mimic breast cancer, particularly tubular carcinoma of the breast. To confuse matters even more, there are sometimes cancerous cells hiding within a radial scar.


Mastitis is a condition in which there is inflammation and swelling of the breast with or without the presence of an infection. It is a common condition affecting, on average, 20% of nursing mothers but may occur in women who aren't breastfeeding as well. The breast is often red and tender and may be associated with flu-like symptoms such as a fever, chills, and body aches. Treatment often includes antibiotics, rest, and management of breastfeeding.

The problem is that inflammatory breast cancer can look very much like mastitis early on, and is often diagnosed only after a woman has been treated first for mastitis (often with no improvement in symptoms). Inflammatory breast cancer accounts for between 1% and 5% of breast cancers and women do not usually have a lump and it doesn't usually show up on a mammogram. In comparing inflammatory breast cancer with mastitis there are many similarities, though with inflammatory breast cancer there may be nipple inversion and an orange peel appearance to the skin as well. With mastitis, it is the build-up of white blood cells and increased blood flow that results in the symptoms, whereas with inflammatory breast cancer, symptoms are related to the presence of cancer cells blocking lymphatic channels in the breast.

Granulomatous mastitis is a variant of mastitis often caused by rheumatoid conditions, sarcoidosis, or tuberculosis. It can also be idiopathic. Granulomatous mastitis results in long periods of inflammation in the breast and can initially be difficult to distinguish from inflammatory breast cancer on a mammogram, ultrasound, or MRI.

Cooper's Ligament Fibrosis and Scars

Cooper's ligaments are the supporting structures of the breast, and most people are familiar with these as the ligaments you wish to keep in shape as you age. Stretching of these ligaments over time are behind to slang "Coop's droop" referring to the "descent" of breasts with age.

Fibrosis of Cooper's ligaments can occur due to both benign and malignant breast changes.This is one way in which underlying tumors result in nipple retraction and changes in the surface of the appearance of the skin. But benign breast conditions, such as inflammation, fat necrosis, and biopsy scars can also damage these ligaments causing the surface appearance of breast cancer.


Sarcoidosis is a benign condition marked by the formation of granulomas throughout the body. When present in the lungs, it commonly causes a cough and shortness of breath, though 50% of people are asymptomatic at the time of diagnosis.

The problem of sarcoidosis is of greater concern for women who have already been diagnosed with early-stage breast cancer. Sarcoidosis granulomas can appear very much like metastatic cancer on a PET (positron-emission tomography) scan, and even biopsy samples can be difficult to analyze. For example, granulomas and breast cancer metastases can look virtually identical on a sentinel node or lymph node biopsy. This could lead to the false diagnosis of lymph node positive or metastatic breast cancer in a person who really has early-stage lymph node-negative disease.

Diabetic Mastopathy

Diabetic mastopathy is a benign tumor that may be found in women (and men) with type 1 and type 2 insulin-dependent diabetes. On exam, diabetic mastopathy appears as a large, painless breast mass that can imitate breast cancer. It is caused by a combination of inflammation and dense fibrosis in the breasts.

Imaging findings can be indistinguishable from breast cancer on mammogram, ultrasound (where it can look particularly ominous) and MRI. On these studies, the condition appears as ill-defined masses. A core needle biopsy is usually needed to make the diagnosis.


Breast fibromatosis, also called a desmoid tumor, accounts for around 0.2% of breast masses. It is not certain what causes this condition but it appears to run in families. On mammogram and ultrasound, fibromatosis can mimic breast cancer findings. The diagnosis is usually made with a core needle biopsy.

Granular Cell Tumor

Granular cell tumors, also called breast granular cell myoblastomas, can appear very much like breast cancer. While usually benign, they arise from Schwann cells, cells found in the nervous system.

These tumors are often fibrotic causing skin retraction and fixation to the fascia underlying the breast. This results in a lump which appears fixed, similar to a breast cancer. They are also usually very hard, similar to cancer as well. On imaging studies such as mammogram they also resemble cancer. They tend to have well-defined borders but with spiculation suggestive of cancer.

Granular cell breast tumors are more common in people between the ages of 40 and 60 and they occur in both women and men.

Spindle Cell Lesions

Breast lesions containing spindle cells are a challenge on many levels. Spindle cell lesions can feel and look indistinguishable from breast cancer, but these lesions can appear very much like cancer under the microscope after a biopsy as well. In addition, both benign and cancerous breast lumps can have spindle cells. Fortunately, spindle cell lesions are uncommon, but still must be considered in the differential diagnosis of breast biopsy samples.

Myofibroblastoma is an unusual benign breast tumor that falls under the category of spindle cell lesions. They may occur in both women and men and can be challenging to diagnose.

Pseudoangiomatous Stromal Hyperplasia (PASH)

Pseudoangiomatous stromal hyperplasia or PASH is a condition found most commonly in women around the time of menopause and older. It appears to be more common in those who have taken hormones (such as birth control pills or hormone replacement therapy), those who use alcohol, and those who are overweight. These benign tumors tend to grow quite large, and an open biopsy (rather than simply a core biopsy) is usually needed to make the diagnosis.

A Word From Verywell

As noted above, there are many benign breast conditions that can mimic breast cancer on exam, imaging studies, and in some cases even under the microscope. While missing a breast cancer is what many people fear, mistakenly thinking that a lump or change is cancer when it's not can be emotionally upsetting as well. Conditions that look like breast cancer can lead to additional imaging studies, core biopsies, and even open biopsies, all of which take an emotional toll.

The most important thing you can do if you find any form of abnormality, or hear of one on your mammogram, is to ask a lot of questions. Stay in the driver's seat and expect answers as well. Being your own advocate can go a long way in getting both the care you deserve and limiting the amount of emotional trauma these common abnormalities bring to our lives.

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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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Additional Reading

By Lynne Eldridge, MD
 Lynne Eldrige, MD, is a lung cancer physician, patient advocate, and award-winning author of "Avoiding Cancer One Day at a Time."