Causes of a Breast Lump, Mass or Growth

Identifying the cause of a single breast lump or multiple growths depends on a number of factors. A thorough assessment of a person’s medical history, including family history and use of prescription medication, and evaluation of the type of breast lump will assist with identifying likely causes. The presence of additional features like nipple discharge, breast pain, breast swelling and deformed nipples will further help with narrowing down the most likely causes.

Causes of Breast Lumps


  • Mastitis is inflammation of the breast most frequently caused by an infection. It is fairly common in women who are breastfeeding (postpartum mastitis). A cracked nipple may be the entry point for bacteria, which together with stagnation of milk due to a blocked milk duct, can either cause a breast abscess if the infection extends deep into the breast tissue or it may spread more superficially in the skin to develop into cellulitis. Nipple piercing is another cause of mastitis.
  • Mammary duct ectasia is a condition most commonly seen in women nearing menopause. There may be inflammation and blockage of the ducts beneath the nipples causing pain, swelling and discharge.


  • Breast injury can produce a local hematoma, which is swelling due to collection of blood within the breast tissue, that may form a lump in the breast.
  • Fat necrosis is damage to the fat cells in the breast as a result of trauma. It will be felt in the breast as a single, firm, non-tender lump.

Benign or Non-cancerous Conditions

  • Fibroadenoma is a painless, round, smooth, mobile lump felt within the breast tissue. It is the most common non-cancerous breast lump seen in women and usually occurs in young women.
  • Fibrocystic breast disease (fibroadenosis of the breast) is commonly seen in women of child-bearing age and in women nearing menopause. It is often related to the action of fluctuating hormones. The lumps may be unilateral or bilateral and may be felt as irregular firm lumps.
  • Breast cysts are usually bilateral and often there may be more than one cyst present in a breast.
  • Galactocele or a milk cyst is commonly associated with lactation and may develop when a milk duct gets clogged. This leads to a collection of milk in small pockets in the breast. If infected, it may develop into a breast abscess.
  • Breast hamartoma is a well-circumscribed breast lesion with varying amounts of fat, epithelial and fibrous tissues. It may present as a painless, soft breast lump, similar to a fibroadenoma.
  • Pseudocyst is a cerebrospinal fluid (CSF) pseudocyst in the breast. It is an extremely rare condition which has been known to produce a breast lump. It usually arises due to damage to a venticuloperitoneal (VP) shunt during a mammogram or breast augmentation procedure.
  • Pseudolumps of the breast is a complication of breast augmentation surgery where  toughened silicone implants or scar tissue  may be felt as a breast lump.
  • Sclerozing adenosis is a benign breast condition which occurs in the lobes involving fibrocystic changes in the breast. When an enlarged lobule is distorted by scar-like fibrous tissue, it is known as sclerozing adenosis. It is associated with an increased risk of developing breast cancer.
  • Lipoma is a lump formed by a collection of fatty tissue beneath the skin of the breast. Lipomas occur quite frequently in the breast and it sometimes becomes difficult to distinguish it from other soft tissue tumors.
  • Breast lumps in newborn babies may occur due to the action of maternal hormones. Once the estrogen level falls, these lumps disappear without any additional treatment necessary.
  • Intraductal papillomas are small growths in the lining of the milk ducts near the nipple. It may be felt as small lumps behind or near the areola.
  • Phyllodes tumor, also known as cystosarcoma phyllodes, it is a painless growth in the connective tissue of the breast. It is a relatively large tumor (average size of 5 cm), firm, mobile and well circumscribed. It is usually benign but may become malignant in some cases.

Breast Cancer

A lump due to breast cancer is usually painless, often hard, with irregular edges, and fixed to the underlying tissue. It may be accompanied by skin changes such as redness, warmth and pitting of the skin, nipple retraction or nipple discharge.  A breast examination, mammography and biopsy is necessary to confirm/exclude breast cancer. Early detection of breast cancer increases the chances of successful treatment and survival.

Related Articles

  1. Breast Lumps
  2. Breast Secretion
  3. Breast Pains
  4. Breast Swelling

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