Breast cancer

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Other non-cancerous breast conditions

The following are less common non-cancerous conditions of the breast. Most of these conditions do not increase the risk of developing breast cancer.


Adenosis is when the glands that make milk (called lobules) become enlarged and there are more glands than normal.

Adenosis is usually found during mammography. In some cases, a healthcare professional may be able to feel the enlarged lobules during a clinical breast exam. Adenosis usually doesn’t need to be treated.

If the enlarged lobules are surrounded by scar-like tissue, it is called sclerosing adenosis. This condition may slightly increase a woman’s risk of developing breast cancer. Women with sclerosing adenosis should speak to their doctor about their risk and a personal plan for screening for breast cancer. Doctors may do a core biopsy on an area of sclerosing adenosis to check for cancer cells.

Breast infection

A breast infection (called mastitis) is an infection of the fatty breast tissue. It is caused by bacteria that are found on the skin. Most breast infections develop in breastfeeding women.

Symptoms of a breast infection include swelling, pain or tenderness, redness or warmth, nipple discharge, itching and fever. A breast infection can also cause a pocket or collection of pus (called an abscess) in the breast tissue.

If you have symptoms of a breast infection, your doctor will do a clinical breast exam. You may also have an ultrasound to look for an abscess.

Breast infections can be treated with antibiotics and by putting a warm moist cloth on the breast several times a day. If there is an abscess, you may need to have surgery to drain it.

If these treatments do not clear a breast infection, your doctor may order other tests, such as mammography.

Fat necrosis

Fat necrosis is scar tissue that forms when fatty breast tissue is damaged or injured. Sometimes a cyst filled with oily fluid may develop in the area of fat necrosis. It does not increase a woman’s risk for breast cancer.

The most common causes of injury to breast tissue are biopsies, surgery and radiation therapy. Seat belt injuries or blows to the chest may also cause fat necrosis.

Fat necrosis doesn’t usually cause any signs or symptoms. It will sometimes cause a small round painless lump. It is usually found during a routine mammography or ultrasound. Doctors may do a core biopsy or fine needle aspiration (FNA) on the area of fat necrosis to confirm the diagnosis.

Most areas of fat necrosis go away on their own and don’t need to be treated. Doctors may use surgery to remove the area if the biopsy did not confirm the diagnosis of fat necrosis. It may also be offered if the area starts to get larger or becomes painful.


Gynecomastia is the enlargement of breast tissue in men. It is a common non-cancerous condition caused by a change or imbalance in the hormones testosterone and estrogen. It occurs mostly when hormone levels change during puberty and as a man ages.

Risk factors that may increase a man’s chance of developing gynecomastia include:

  • liver, kidney or thyroid disease
  • injury or inflammation of the testicles
  • certain medicines, such as those used to treat ulcers, high blood pressure and heart failure
  • anabolic steroids (used by some athletes and weightlifters)
  • testicular, lung, stomach or kidney cancer, which can increase hormone levels
  • endocrine disorders
  • a rare genetic condition called Klinefelter syndrome

Depending on what causes gynecomastia, it may go away on its own or when the underlying problem is treated. In rare cases, doctors may offer hormonal therapy or breast reduction surgery to treat it.

Mammary duct ectasia

Mammary duct ectasia is when the walls of a milk duct are thicker than normal. The duct gets blocked and fluid builds up behind the blockage. It is more common in women between the ages of 40 and 50.

Mammary duct ectasia can cause:

  • thick green or black nipple discharge
  • pain in the nipple or the breast
  • redness or swelling in the nipple

Mammary duct ectasia usually doesn’t need to be treated and goes away on its own. Your doctor may suggest the following to help relieve pain and discomfort:

  • placing warm cloths on the nipple area
  • taking over-the-counter pain medicines
  • wearing bra pads to absorb the nipple discharge
  • wearing a supportive bra

If mammary duct ectasia does not improve on its own, your doctor may prescribe antibiotics to treat infection or surgery to remove the affected milk duct.

Radial scars

Radial scars are star-shaped abnormal areas made up of gland and supportive tissues in the breast. They are not really scars, but they look like scars when looked at under a microscope. Radial scars are made up of cells that multiply faster than normal cells (called proliferative cells) and so may slightly increase the risk of breast cancer.

Most radial scars are less than 1 cm and cannot be felt in the breast. Radial scars that are larger than 1 cm may be called complex sclerosing lesions.

Radial scars are often found during mammography. But it can be difficult to tell the difference between a radial scar and an invasive breast cancer on mammography. For this reason, most radial scars are removed with surgery. The breast tissue removed is examined under a microscope. Some radial scars can have areas of ductal carcinoma in situ (DCIS) in them.


A male sex hormone that causes male sex characteristics to develop (such as deep voice and facial hair) and stimulates the development of the male reproductive system and sexual activity.

Testosterone is made mainly by the testicles. Small amounts of testosterone are also made in the adrenal glands. It may also be produced in the lab to treat certain conditions.


A female sex hormone that causes the female sex characteristics to develop (such as breasts) and is necessary for reproduction.

Estrogen is made mainly by the ovaries. Small amounts of estrogen are also made in the adrenal glands. It may also be produced in the lab to treat certain conditions or as a type of birth control.

Klinefelter syndrome

An inherited sex chromosome disorder in which men have at least one extra X chromosome. Signs include small testicles, enlarged breasts and lack of facial and body hair.

Klinefelter syndrome is associated with an increased risk of testicular cancer.

Also called XXY syndrome.