Fat necrosis is a benign condition in which damaged and disintegrating fatty tissues form round, firm lumps in the breast tissue. The lumps are usually painless but in some women may be tender. The skin around the lump may look red, bruised or dimpled.

Fat necrosis often occurs in women with very large breasts or in response to a bruise or blow to the breast (although many women may not be able to recall a specific injury). For example, this condition sometimes occurs following an automobile accident in which the seat belt has squeezed the breast. Fat necrosis may also result from breast surgery (including breast-reduction surgery) or radiation to the breast.

These lumps are not malignant and there is no reason to believe that they increase a woman's risk of cancer. Fat necrosis is usually detected as a result of examination or imaging for other conditions.

Care: In some cases, physicians will keep a watch on the lump through several menstrual cycles, and may perform a mammogram or ultrasound before deciding whether to perform a biopsy to remove it surgically. Usually, though, an area of fat necrosis will not require any treatment and will clear up on its own within a few weeks. In some patients, the lump can leave behind an oily cyst that can be drained with a needle.