Learn about fat necrosis - a benign (not cancer) breast condition - including what it is, what causes it and how it is diagnosed.

1. What is fat necrosis?

Fat necrosis is a benign (not cancer) condition that most commonly develops after an injury or trauma to the breast tissue. 

A lump can form if an area of fatty breast tissue is damaged, for example during a or surgery. 

Necrosis is a medical term that describes damaged or dead tissue.

It can occur anywhere in the breast and can affect women of any age. 

Men can also get fat necrosis, but this is very rare. 

Having fat necrosis does not increase your risk of developing breast cancer.

2. Symptoms of fat necrosis

Fat necrosis feels like a firm, round lump or lumps.

It’s usually painless, but in some people it may feel tender or even painful. 

The skin around the lump may look thickened, red, bruised or occasionally dimpled. 

Sometimes fat necrosis can cause the nipple to be pulled in.

It’s important to get breast lumps checked by your doctor. Even though most breast lumps are not cancer, a change to the way your breast feels or looks could be a sign of breast cancer.  

3. What causes fat necrosis?

Fat necrosis can be caused by any type of trauma to the breast including:

  • Breast biopsy
  • Breast surgery including , breast reduction, reconstruction or enlargement 
  • to the breast 
  • Lipomodelling - when fat taken from another part of the body is injected into the breast, for example to improve the appearance of dents following surgery 
  • Damage or injury caused by an accident such as a seat belt injury or fall 

Fat necrosis can be found at any time after breast surgery or an injury.

Sometimes it develops without any trauma and many women with fat necrosis do not remember a specific injury.

4. Diagnosing fat necrosis

If you see your GP because of a breast lump, they’ll examine your breasts and will likely refer you to a breast clinic where you’ll be seen by specialist doctors or nurses.

At the breast clinic most people have a breast examination followed by one or more of the following tests: 

  • A mammogram (breast x-ray)
  • An ultrasound scan (using sound waves to produce an image)
  • A core biopsy (using a hollow needle to take a small sample of tissue to be looked at under a microscope – several tissue samples may be taken at the same time) 
  • A fine needle aspiration (using a fine needle and syringe to take a sample of cells to be looked at under a microscope)  

During a breast examination fat necrosis can be confused with breast cancer. It may also look like breast cancer on x-rays and scans, which can cause a lot of anxiety. 

If the mammogram or ultrasound scan clearly shows fat necrosis, you may not need more tests. 

If there’s any doubt about what the mammogram or ultrasound scan shows, you’ll have a biopsy. 

Sometimes fat necrosis is found by chance after a mammogram during breast screening.

5. Treatment for fat necrosis

Most people do not need treatment

Fat necrosis is harmless so you will not usually need any treatment or follow-up. 

In most cases the body will break it down over time. This could take a few months.

It’s important to go back to your GP if the lump gets bigger or you notice any other changes to your breasts.

Surgery 

Surgery is usually avoided if possible because it can sometimes cause further fat necrosis. 

However, an operation to remove it may be recommended if: 

  • The biopsy has not given enough information to confirm a diagnosis of fat necrosis 
  • The fat necrosis is uncomfortable or tender 
  • The lump or lumpy area does not go away by itself or gets bigger

Excision biopsy 

If you need surgery, you’ll usually have an excision biopsy. 

This is an operation to remove the dead or damaged tissue, and may be done using either a local or a general anaesthetic. 

The operation will leave a small scar but this usually fades over time. 

Vacuum assisted excision biopsy

Some people are offered a vacuum assisted excision biopsy. 

After an injection of local anaesthetic, a small cut is made in the skin. A hollow probe connected to a vacuum device is placed through the cut. 

Using ultrasound or mammography as a guide, breast tissue is sucked through the probe by the vacuum into a collecting chamber until the fat necrosis has been removed. 

This may mean an operation under a general anaesthetic can be avoided. 

Pain relief 

If fat necrosis causes discomfort but you’re not having an operation to remove it, your doctor may suggest treating it with pain relief such as paracetamol or an anti-inflammatory drug like ibuprofen. 

Breast cysts

Sometimes, within an area of fat necrosis the damaged tissue can form a cyst containing an oily fluid (oil cyst). 

Breast cysts don’t usually need any treatment or follow-up.

6. Can fat necrosis increase the risk of breast cancer?

Having fat necrosis does not increase your risk of developing breast cancer. 

Some people worry the fat necrosis might ‘turn into’ breast cancer, but there’s no evidence that this can happen. 

However, it’s still important to be breast aware and go back to your GP if you notice any changes in your breasts, regardless of how soon these occur after your diagnosis of fat necrosis. 

If you have any questions about fat necrosis or would just like to talk it through with a nurse, you can call our free helpline - see below.

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Last reviewed in February 2022. The next planned review begins in February 2024.

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