7 Common Causes for Breast Lumps

Updated in November 2021

​A breast lump is a small mass that, in most cases, is not a sign of breast cancer. It is normally a benign finding, like a fibroadenoma or a cyst, and usually does not require treatment.

You should only suspect breast cancer when the lump has malignant characteristics, such as changes to breast size or shape, or if there is a history of breast cancer in the family (particularly in parents).

If you find a lump during a self-examination, it's important that you see your doctor. He or she will likely order an ultrasound or mammogram to determine whether the lump is benign or malignant, and from there, decide the most appropriate treatment. 

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Main causes of benign breast lumps 

A breast lump that is not connected to cancer is also known as mastopathy. Mastopathy can happen due to hormonal changes (e.g. during your period), or it might be cystic or a sign of breast tissue fibrosis. Some of the most common causes of breast lumps include:

1. Fibrocystic breast changes 

Fibrocystic changes are the most frequent cause of breast lumps and they are related to hormonal changes in a woman's body (e.g. during a period or when undergoing hormonal treatment).

Characteristics of the lump: These lumps normally appear a week before the period starts and disappears a week after the period ends. They can be painful and hard, and may just appear in one breast or both.

2. Simple cysts

Cysts generally occur in pre-menopausal women who are over the age of forty. They are not serious and rarely develop into cancer, so they do not require specific treatment.

Characteristics of the lump: these commonly occur in both breasts and can change in size during menstruation. These lumps may also become more painful after consumption of caffeine, tea or chocolate.

3. Fibroadenoma

A fibroadenoma is a type of lump that is frequent in young women between the ages of twenty and forty. It is caused by excessive growth of the glands that produce milk and breast tissue. 

Characteristics of the lump: they are round, slightly hard and they are moveable with palpation (ie. they are not fixed to just one location). These lumps do not usually cause pain. 

4. Lipoma

Lipoma is caused by a build-up of fatty tissue in the breast and it is not serious. They can even be surgically removed if there is a cosmetic concern.

Characteristics of the lump: Lipomas are soft, (think: small pillows of fat) and are moveable with palpation. However, in some cases, lipomas can also be hard, which can be confused with breast cancer.  

5. Breast infections

Some breast infections, such as mastitis during pregnancy, can also cause an inflammation of the tissues and ducts inside the breast and cause lumps. 

Characteristics of the lump: These lumps cause breast pain, especially when pressed, and the skin will typically be red in the location of the lump.

6. Diabetic mastopathy

Diabetic mastopathy is a rare and serious type of mastitis. This inflammation in the breast  causes pain, redness and the appearance of one or more lumps in the breast that can be confused with cancer. This disease only appears in people who have diabetes and that take insulin. This condition mainly affects women.  

Characteristics of the lump: These lumps are hard masses that are painless when they first emerge. They can also be accompanied by blisters and pus.

7. Plugged milk ducts

A plugged or clogged milk duct is a condition that affects lactating women. It occurs due to inefficient removal of milk in the breast due to reasons like nipple injury, poor infant latching or overabundant milk supply. Plugged milk ducts can cause pain and discomfort, and can lead to mastitis if left untreated.

Characteristics of the lump: A plugged milk duct will often affect just one breast and can cause the appearance of a hard, fixed lump. These lumps are painful (especially when pressed or during breastfeeding) and will often be surrounded by an area of engorgement.

Tests to identify the type of breast lump 

Ultrasounds and mammograms are the most common tests used to diagnose breast lumps. The doctor will often use their own examination (inspection and palpation) combined with imaging results to reach a diagnosis.

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The result of a mammogram is standardized using a BI-RADS classification system. Mammogram test results are as follows:

  • Category 0: test did not manage to diagnose anomalies and other complementary tests will be necessary;
  • Category 1: normal result, repeat in one year;
  • Category 2: benign alterations, no risk of cancer, repeat in one year;
  • Category 3: possible benign alteration, with a 3% risk of cancer, it is recommended you repeat the test in six months time;
  • Category 4: possible malignant alterations with a 20% risk of cancer, a biopsy will be necessary as well as an anatomopathological examination of the breast tissue;
  • Category 5: possible malignant alterations with a 95% risk of cancer, and surgery will be necessary to remove the anomaly, and a pre-op biopsy may be necessary;
  • Category 6: confirmed breast cancer diagnosis.

Breast lumps that are described as hypoechogenic or hypoechoic do not confirm the severity or the malignancy of the nodule. These are just expressions used to communicate lump characteristics.

Treatment for breast lumps

Breast lumps do not usually require any treatment, as they typically do not increase in size or cause any symptoms in the patient. However, when the lump is painful or its size is very big, the doctor may recommend taking a daily contraceptive pill to help with hormonal influence on the lump.

Breast lumps in men

Breast lumps in men are usually linked to male breast cancer, but they can also be benign. Therefore, if you notice a lump, consult your doctor so that the origin of the lump can be identified.