Fat Necrosis and Oil Cysts in the Breast
Fat necrosis happens when an area of the fatty breast tissue is damaged, usually as a result of injury to the breast. It can also happen after breast surgery or radiation treatment. Fat necrosis is more common in older women with very large breasts.
As the body repairs the damaged breast tissue, it’s usually replaced by firm scar tissue. But some fat cells may respond differently to injury. Instead of forming scar tissue, the fat cells die and release their contents. This forms a sac-like collection of greasy fluid called an oil cyst.
Oil cysts and areas of fat necrosis can form a lump that can be felt, but usually doesn’t hurt. Sometimes the skin around the lump looks thicker, red, or bruised. These changes can be hard to tell apart from cancers on a breast exam or even a mammogram. A biopsy (removing all or part of the lump to look at the tissue under the microscope) may be needed to find out if the lump contains cancer cells.
Oil cysts (like other cysts) can often be seen on ultrasound and then diagnosed by needle aspiration. This is where a thin needle is put into the cyst to take out the fluid.
Fat necrosis and oil cysts usually don’t need to be treated. Sometimes fat necrosis goes away on its own.
The needle aspiration done to remove the fluid in an oil cyst can also serve as treatment.
In some cases, surgery may be used to take out the lump or lumpy area if it gets bigger or becomes bothersome.
How do fat necrosis and oil cysts affect your risk for breast cancer?
These breast changes do not increase a woman’s risk of breast cancer.
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Last Medical Review: March 16, 2015 Last Revised: April 21, 2016
- Fibrosis and Simple Cysts in the Breast
- Hyperplasia of the Breast (Ductal or Lobular)
- Lobular Carcinoma in Situ (LCIS)
- Adenosis of the Breast
- Fibroadenomas of the Breast
- Phyllodes Tumors of the Breast
- Intraductal Papillomas
- Granular Cell Tumors of the Breast
- Fat Necrosis and Oil Cysts in the Breast
- Duct Ectasia
- Other Non-cancerous Breast Conditions