An Overview of Breast Fat Necrosis

This harmless condition results when fatty breast tissue is damaged

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Breasts are mostly made up of fatty tissue, and if that tissue is damaged by injury, surgery, or radiation therapy, a lump can form. This is called fat necrosis. The condition can be frightening because the lump can both feel like breast cancer and look like breast cancer on a mammogram. But fat necrosis is a benign (non-cancerous) condition and, while sometimes people think it can "turn into" cancer, there's no evidence that it leads to the development of breast cancer. These so-called "pseudolumps" can occur at any age and appear anywhere in the breast, but they're more common in women who are obese or have very large breasts.

Necrosis is a medical term used to describe damaged or dead tissue.


Fat necrosis develops when the body replaces damaged cells with firm scar tissue. It may feel like a hard, round lump, or like a section of thick skin. It's usually painless, but your breast may feel tender or painful in the area surrounding the necrosis. The skin around the lump may look red and bruised. You may see some drainage from the nipple that's nearest the bruised region. Sometimes, your nipple may pull inward a little bit, or your breast skin may dimple above the lump of fat necrosis.

Sometimes, the fat cells don't turn into scar tissue but instead, they die and release their contents. This forms a sac-like collection of oily fluid called an oil cyst. If you have an oil cyst, it may feel like a smooth and squishy lump, similar to the feeling of a small grape under your skin.

One study on fat necrosis found that 97 percent of lumps could be felt and two-thirds were painless. Other characteristics of fat necrosis included:

  • The lumps are often periareolar (around the nipple) and superficial (are felt just under the skin)
  • Bruising or tenderness was noted 24 percent of the time.
  • Skin tethering or dimpling was noted in 14 percent of cases.
  • Nipple retraction was present in nine percent of cases.

After the area of breast fat necrosis appears it may increase in size, decrease in size, or stay the same. It may persist for years or may resolve, leaving behind fibrosis and calcifications that may be seen on a mammogram.


There are a few causes of fat necrosis. They include:

Injury. Fatty breast tissue can incur damage after any type of traumatic breast injury, for instance being hit by a ball or restrained by a seatbelt or airbag during a car accident. Sometimes, though, fat necrosis develops without any trauma and many women with it don’t remember any specific injury.

Radiation treatment. The use of ionizing radiation to treat cancer cells may sometimes cause an area of fat necrosis that can be mistaken for a breast cancer recurrence. This appears to be more common in women who have accelerated partial radiation, a type of radiation given only to the part of the breast that has cancer in it, and radiologists are looking for better ways to evaluate this, including the use of a grading system.

Breast surgery. Any type of breast surgery can result in damage to the fatty tissue, including biopsies (both needle biopsy or a surgical biopsy can cause it), reconstruction, reduction, and lipomodelling (aka fat transfer), which is when fat is taken from another part of the body and injected into the breast. Fat necrosis is more common in those who have breast cancer surgery and also receive adjuvant chemotherapy, which is given to prevent recurrence of the original tumor. The condition is becoming more of a concern with fat grafting during reconstruction since it can be difficult to differentiate fat necrosis from a breast cancer recurrence.


Fat necrosis can be difficult to diagnose because it often looks and feels like many other types of breast lumps. Both during a clinical breast exam and a mammogram or other imaging study, the mass may look like a malignant breast tumor—dense, with an irregular shape, a spiky border, and a collection of microcalcifications. Fat necrosis in the breast may appear to be atypical lipoma or liposarcoma, types of tumors that are very rarely found in breast tissue. If the fat has turned into liquid, it can look like a cyst on an ultrasound. Fat necrosis can take on different appearances over time so follow-up mammograms will show a change in the mass.

The upshot: To diagnose fat necrosis, a biopsy (removing all or part of the lump to look at the tissue under the microscope for signs of cancer) is often needed. Oil cysts are usually diagnosed with needle aspiration, a type of biopsy procedure in which a sample of the fluid is removed from the mass via a thin, hollow needle and then microscopically examined.


According to the American Cancer Society, fat necrosis and oil cysts usually don’t need to be treated. Sometimes fat necrosis goes away on its own, as the body breaks it down over time. In cases where the mass is large and causing discomfort or distress, it may be removed with a vacuum-assisted core needle or a lumpectomy. If a needle aspiration is done to remove the fluid in an oil cyst, it can also serve as treatment. Oil cysts can also be surgically removed.

If fat necrosis causes pain, you can take Advil (ibuprofen) and aspirin. For severe pain, ask your doctor for prescription pain medicine. If you've recently had a breast injury or surgery and you suspect fat necrosis, try warm compresses and gentle massage—with care, sometimes the tissue will heal and the necrosis will resolve on its own. But even if your symptoms go away, be sure to mention them—and any other changes in your breast—to your doctor.


Benign breast conditions like fat necrosis often crop up without an explanation, such as an injury, so they can't really be prevented or avoided. However, since being overweight can raise your risk of the condition, losing weight may reduce your risk of developing it.

A Word From Verywell

Fat necrosis can be frightening for women and a challenge for physicians. That said, through a combination of imaging studies, and a biopsy if needed, you and your doctor can be sure the changes you're experiencing are remnants of past damage to your breast tissue and nothing worse.

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