Breast lumps can occur for a number of reasons. Sometimes a lump is cancerous, but most breast lumps are benign, or noncancerous.

The breast consists of fatty tissue, which connects to muscles on the chest. It contains glands and ducts that produce and deliver milk to infants. Milk leaves the breast through the nipple.

The breast changes over time. Depending on need, there may be more or fewer milk glands and ducts.

A breast lump can be connected to any of these tissues.

[Causes of breast lumps]Share on Pinterest
Breast lumps can form from either fatty or glandular breast tissue.

The breasts change throughout the monthly cycle and the life cycle. When the breasts feel lumpy or fibrous, this is known as a fibrocystic changes.

Pain and lumpiness may occur in general or at some times of the month. Some women with fibrocystic breast changes experience no symptoms.

Factors that can lead to breast lumps include fibroadenosis, fibroadenomas, breast cysts, abscesses, and mastitis.

Fibroadenosis

Fibroadenosis, or fibrocystic breasts, refers to a group of conditions that can affect the breast. They can affect one or both breasts. Discomfort may range from slight to severe pain. They may be more troublesome around menstruation.

Symptoms can include:

  • uneven texture or lumps in the breast
  • breast pain
  • swollen breast

The exact cause is unknown, but it may happen when the breast tissue reacts to hormonal changes in the breast due to menstruation.

Fibroadenomas are a common type of breast lump. A fibroadenoma is a smooth, solid lump. It may feel rubbery. This type of lump develops outside the milk ducts in the breast. The cause is unknown but may be linked to reproductive hormones.

These types of lump are sometimes called "breast mice" because they can move around.

They are more likely to affect women under 40 years, and especially those in their 20s.

Fibroadenomas do not disappear after menstruation. During pregnancy, they may become larger. They sometimes go away on their own, and they often disappear after menopause.

[Checking breast lumps]Share on Pinterest
Manually self-checking for breast lumps can be the first step to ruling out a more serious complication.

Breast abscesses

These are painful lumps that form in the breast. They contain pus. An abscess is a sign of infection.

Other symptoms may include:

  • a fever
  • redness and swelling in the affected area

A breast abscess normally happens because of a bacterial infection. The bacteria can enter through cracks in the skin of the nipple, for example, during breastfeeding.

Breast cysts

Breast cysts are sacs in the breast tissue that fill with fluid. They form smooth, firm, round or oval-shaped lumps.

They are more likely to affect women between the ages of 30 and 60 years, and especially those who are approaching menopause.

Cysts can range in size from very small to over one inch across. There may be only one, there may be several, and they can affect one or both breasts.

As with other breast lumps, it is not clear exactly what causes cysts, but they are hormone-related.

A cyst does not always need treatment, but sometimes a needle aspiration may be done to remove the fluid. However, the cyst can fill up again.

It is not linked to cancer.

Mastitis

This usually occurs when a woman is breastfeeding, but it can happen at other times. It is an infection.

It happens when bacteria enter the milk ducts through cracks in the nipple. The duct can become blocked, and pus builds up in the breast. The breast tissue becomes inflamed and swollen.

Treatment includes warm compresses, pain-killers, and possibly antibiotics.

Other causes

Trauma, such as a blow to the breast, can cause a hard, irregularly shaped lump to form. It usually goes away without intervention.

A lipoma is a fatty growth. It occurs in the fatty breast tissue. Treatment is not usually necessary, but a doctor can remove a lipoma that is large or causes discomfort.

Diabetic mastopathy is a rare, noncancerous condition of the breast that is usually diagnosed in premenopausal women with type I diabetes. They are painless, fibrous lumps that are benign but can be misdiagnosed as breast cancer. They can be removed but tend to recur.

Intraductal papilloma is a growth in the milk duct, rather like a wart.

[Breast lump mammogram]Share on Pinterest
Mammography scans provide imaging that highlights the nature and development of a breast lump.

Sometimes, a lump is cancerous. Most cancerous breast lumps are not painful, but between 2 and 7 percent of painful lumps receive a malignant diagnosis.

A malignant breast lump is more likely to:

  • feel firm
  • be clearly defined
  • be fixed in one place
  • be the same at any point during the menstrual cycle
  • develop after menopause

There may also be:

  • nipple discharge
  • dimpling of skin on the breast
  • change in how the nipple looks, for example, a sunken look

Exposure to estrogen during a woman's lifetime may increase the risk of some types of breast cancer.

Factors that reduce this exposure, such as the onset of menstruation and menopause may affect the risk.

Women who develop breast cancer are more likely to have the following characteristics:

  • being over 50 years of age
  • having a family history of breast cancer
  • having previous diagnosis of breast cancer
  • never having children, or having children after the age of 30 years
  • never having breast-fed a baby
  • menstruation starting at an early age
  • menopause starting after the age of 55 years
  • radiation exposure to the chest
  • use of combined hormone replacement therapy for several years after the age of 50 years
  • high consumption of alcohol
  • having an inherited genetic mutation, like BRCA1 or BRCA2

Studies suggest that the longer a woman has breast-fed, the lower her chance of breast cancer.

This may be because a woman does not ovulate while she is breast-feeding, so her exposure to estrogen is lower.

Breast cancer may be invasive, affecting nearby tissues, or it may be in one location only. It may be fast-growing or slow-growing.

If the cancer is diagnosed when the cells have not spread beyond the duct or lobule where it started, treatment is easier.

Although most breast lumps are not cancerous, any woman who is concerned about a breast lump should seek medical advice.