What is Fat Necrosis?

Fat Necrosis is a pseudo-mass which may develop within the breast, often presenting as a lump which a woman discovers herself. Sometimes fat necrosis only shows up on a screening mammogram.

Fat necrosis almost always occurs as an after effect of surgery of the breast.

In the minority of cases the necrotic mass comes from trauma, like a punch or knock to the breast. Fat necrosis may also develop following radiation treatments.

This condition becomes a cause for concern in breast cancer screening only because the mammographic appearance can mimic breast carcinoma. Because it often presents as a lump, this can cause a woman to worry that it might be breast cancer.

Does necrosis mean something bad?

In this case, no it is not bad.

However, the good news is that fat necrosis is completely harmless and it does not increase the risk of future breast cancer development in any way. It is not related to cancer at all, but is rather the result of a disruption of oxygen supply to fat cells.

What do you mean?

Sometimes, not often, the ‘necrosis‘ word causes too much worry.

For future reference, keep in mind that this page is a wee bit old. Yes, wee wee old! However, we have a new page on benign breast conditions, including fat necrosis.

Fat necrosis occurs when fat cells die

In the microscopic image below, the darker purple and shriveled bunches are remnants of fat cells that are dead. This is ‘fat necrosis’ and if there are large enough accumulations it can show on a mammogram or possibly grow into a small lump.

What is fat necrosis?

‘Necrosis‘ means ‘cell destruction’ or ‘cell death and decay’. For some reason, the blood supply to a fat lobule becomes disrupted. So, when the fat cells do not get enough oxygenated blood, they die.

Once a cell dies – any cell in the body and not just the breast, chemical-molecules are released that start the process of trying to get rid of the dead cells. This process includes enzyme action that break up fat into smaller molecules that the bloodstream then absorbs.

The calcium deposits that occur in fat necrosis are essentially the result of the action of these enzymes.

What are the Symptoms of Fat Necrosis in the Breast?

Women with this condition of the breast may experience:-

fluid discharge from the nipple
breast pain
Discoloration or dimpling of the skin on the surface of the breast
Nipple inversion or retraction is also not uncommon

Sometimes there are no physical symptoms at all.

Breast Cancer Screening mammograms and fat necrosis

Fat necrosis forms into a lump or pseudo-mass due to fat cells that have either died or been damaged. A mammogram will easily detect this mass.

The only concern is that sometimes the shape and features of a fat necrosis pseudo-mass can be very similar to certain kinds of breast cancer.

Fat necrosis tends to have an irregular or rounded outline. Furthermore, these lumps tend to be smaller in size than other types of masses, usually less than 2cm in diameter.

A Breast X-ray

In the X-ray image of fat necrosis below one can see a thin outer ring shape. That is the outside edge of the fat necrosis build up.

Because of the ‘fat density’ inside the ring, (basically clear, not absorbing light like cancer cells do) one can be quite sure that it is fat necrosis.

(Note, however, that most fat necrosis do not have a little round blob in the center like this example does.)

Breast fat necrosis may have a fibrotic reaction

Typically, one observes with fat necrosis quite a bit of liquefied fat and the presence of calcifications. But at other times, depending on the age of the pseudo-mass, fat necrosis may show more of a ‘fibrotic‘ reaction.

This means that fibrous tissue (sometimes called ‘scar tissue’) has developed in the areas where the fat cells have died. In these cases the borders will be thicker, less regular, and possibly speculated.

It is these kind of features, possibly described as an ‘irregular, speculated mass’ which makes screening physicians extra cautious and thorough in ruling out breast cancer.

Radiologists can usually spot fat necrosis lesions

An experienced radiologists can usually recognize subtle features that identify fat necrosis. Often medics will also take sonograph (ultrasound) images as this has proven to be a very useful method of ruling out malignancy.

With ultrasound, fat necrosis tends to present with an increased echogenicity of the subcutaneous tissues, and ‘hyperechoic’ masses are almost always benign.

Mammograms are still generally the best way to discover fat necrosis

Magnetic Resonance Imaging is sometimes neessary for additional confirmation of fat necrosis, but it’s effectiveness is debatable.

Even with the greater specificity of MRI, it does not tend to convincingly show those features which can emphatically rule out malignant carcinoma.

So, the general consensus seems to be that mammograms are probably the best way to investigate fat necrosis. However, if there is any uncertainly at all your breast cancer specialists will request a biopsy.

Treatment of Breast Fat Necrosis

Fat Necrosis requires no treatment at all. Some family physicians suggest applying a warm compress to the breast for about 30 minutes every four hours for a day or so. Generally, however, the situation will just resolve by itself.

References

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Coady AM, Mussurakis S, Owen AW, Turnbull LW. (1996) MR imaging of fat necrosis of the breast associated with lipid cyst formation following conservative treatment for breast carcinoma. Clin Radiol 1996; 51:815 –817 https://www.clinicalradiologyonline.net/article/S0009-9260(96)80014-6/pdf
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Hogge JP, Robinson RE, Magnant CM, Zuurbier RA. (1995) The mammographic spectrum of fat necrosis of the breast. RadioGraphics 1995; 15:1347 -1356 https://www.ncbi.nlm.nih.gov/pubmed/8577961
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Lövey K, Fodor J, Major T. (et al). (2007) Fat necrosis after partial-breast irradiation with brachytherapy or electron irradiation versus standard whole-breast radiotherapy–4-year results of a randomized trial. Int. J. Radiat. Oncol. Biol. Phys. 69 (3): 724–31 https://www.ncbi.nlm.nih.gov/pubmed/17524571
Purushotham AD, Britton P, Bobrow LA. (2002) Prospective study of benign breast disease and the risk of breast cancer. JAMA 2002
Taboada J, Stephens T, Krishnamurthy S, Brandt K, Whitman G. (2009) The many faces of fat necrosis of the breast. AJR 2009; 192:815-825 https://www.ncbi.nlm.nih.gov/pubmed/19234281
Villeirs G, Van Damme S, Heydanus R, Serreyn R, Kunnen M, Mortier M. (2000) Heparin-induced thrombocytopenia and fat necrosis of the breast. Eur Radiol 2000;10 : 527–530 https://www.ncbi.nlm.nih.gov/pubmed/10757010

More mammogram images showing fat necrosis