An Overview of Breast Hematomas

These "breast bruises" don't cause cancer

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A breast hematoma is a collection of blood that forms under the skin's surface. It's not unlike having a large bruise in your breast. The mass it forms is not cancerous, but it can sometimes lead to inflammation, fever, skin discoloration, and may leave behind scar tissue that mimics the shape of a breast tumor.

A breast hematoma can happen to anyone regardless of age or menopausal status. It may be caused by trauma, or procedures like a breast biopsy or breast surgery. Breast hematomas are usually visible on a mammogram, and can sometimes look like breast cancer on other imaging as well. Treatment usually consists of waiting for the hematoma to go away over time, but surgery may sometimes be needed.


You can usually see and feel a hematoma because it's often just below the skin, where blood has collected and clotted. The pooled blood may absorb bacteria and the surrounding tissue becomes inflamed, resulting in swelling. The skin above a hematoma will appear to be bruised and, in the case of surgery, broken.

When feeling a hematoma, it may feel like a firm lump beneath the skin. That can be frightening if you're familiar with the common symptoms of breast cancer.

Most hematomas are small (about the size of a grain of rice), but some can be as big as plums or even a grapefruit.


A breast hematoma may be caused in several ways. The commonality is that, most of the time, you will be aware of either the injury or procedure that precedes it.

Possible causes of a hematoma include:

  • Injury to the breast (sports injury, car accident)
  • Weak blood vessel breaking in response to a bump or jolt
  • Breast implant surgery (postoperative bleeding)
  • Therapeutic (not cosmetic) breast surgery, such as a lumpectomy or mastectomy
  • Core needle breast biopsy (rare): The risk of a hematoma is roughly twice as high when a vacuum-assisted procedure is used.

Those on aspirin or blood thinners, such as Coumadin (warfarin) and heparin, are at particular risk for a hematoma regardless of the above.

If symptoms occur without an injury, surgery, or some other procedure, the diagnosis of hematoma should be suspect, as some other conditions are mimics.


A small hematoma probably won’t be seen on a mammogram. However, if the hematoma is large enough to be picked up this way, it will usually appear as a well-defined oval mass. If it resolves on its own, it won’t show up on your next mammogram, but it might look like a tumor with a spiky outline if it was large enough to cause scar tissue or to cause breast tissue to become re-arranged (architectural distortion).

Hematomas often leave behind calcifications (calcium deposits) as well, but these are large in contrast to the microcalcifications on a mammogram that raise suspicion about possible cancer.

Hematomas are not uncommonly found along with seromas, pockets of fluid in the breast that frequently occur after breast surgery. A breast ultrasound is often the best test for evaluating a possible seroma.

While breast hematomas can leave behind scarring that sometimes mimics breast cancer, they do not increase the chance that a person will develop breast cancer in the future.

Hematoma vs. Tumors

In the case of a questionable breast mass, such as a hematoma that caused scar tissue and resembles a tumor, it's usually sufficient to do an ultrasound after an abnormal mammogram to see if there's a hematoma. In some cases, a biopsy may be done. The pathology report can tell you whether the mass is benign (not cancerous) or malignant (cancerous).


Smaller breast hematomas will go away on their own, given enough time. The body usually simply reabsorbs the blood and breaks it down, as it does with any bruise. Using a heated compress or heating pad a few time a day can help this along.

Larger breast hematomas may need to be surgically removed. In some cases, a breast hematoma will spontaneously recur.

It's important to see your doctor if you have a large hematoma, and especially if you develop a hematoma unrelated to an injury to your breast. Both a mammogram and a breast ultrasound will likely be recommended, followed by a breast biopsy if the diagnosis is at all uncertain.

A Word From Verywell

Breast hematomas can be uncomfortable, but they usually heal on their own in time. Still, if the hematoma is large or you continue to have bleeding, it may need to be surgically removed. Let your doctor know if a breast hematoma lingers and if you've had one that has resolved, as this will need to be taken into account when future mammograms are reviewed.

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Additional Reading
  • Love, Susan. Dr. Susan Love's Breast Book. Sixth edition. Hachette Book Group; 2015.