An Overview of Breast Hematomas

Rest assured, these breast "bruises" don't cause cancer

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Radiologist reviewing results of patients mammogram
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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 imaging as well. Treatment usually consists of waiting for the hematoma to go away over time, but surgery may sometimes be needed as well.


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.

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

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.

Causes of Breast Hematomas

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 which results in a hematoma. If a hematoma occurs without an injury, surgery, or some form of procedure, the diagnosis should be suspect as some other conditions may mimic a hematoma. 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
  • Core needle breast biopsy (rare): The risk of a hematoma is roughly twice as high when a vacuum-assisted procedure is used.
  • Breast implant surgery (postoperative bleeding)
  • Therapeutic (not cosmetic) breast surgery, such as a lumpectomy or mastectomy

Aspirin and Hematomas

If you're using aspirin for pain relief or as a blood thinner or to prevent heart problems, you will bleed more easily. If you're injured while on aspirin, a hematoma is more likely to occur. Sometimes, a breast hematoma will occur spontaneously (without any injury) among people on aspirin and blood thinners such as Coumadin (warfarin) and heparin.

Diagnosing Breast Hematomas

A small hematoma probably won’t be seen on a mammogram. However, if the hematoma is large enough to be picked up on a mammogram, 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 if it was large enough to cause scar tissue or to cause breast tissue to become re-arranged (architectural distortion), it might look like a tumor with a spiky outline.

Hematomas often leave behind calcifications (calcium deposits) as well, but these are macrocalcifications (large calcifications) 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 Versus 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 the blood reabsorb. 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 are essentially a "bruise" on your breast, and most of the time the cause is fairly obvious, such as an injury to the breast or recent breast surgery. Breast hematomas can be uncomfortable, but they usually heal on their own in time. If the hematoma is large, or if you continue to have bleeding (more common if you have been on blood thinners), it may need to be surgically removed.

The problem often is that these hematomas, especially if they are large, can leave behind scarring. Scarring, in turn, may show up on a mammogram (often with an irregular, spiky outline) raising the concern about breast cancer. Since it's sometimes impossible to differentiate scarring from a mass, or since both conditions may occur nearby each other, breast ultrasound and possibly a biopsy may need to be done to be certain. Rest assured, though, that developing a hematoma doesn't increase the chance of developing breast cancer in the future.

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