Understanding breast lumps and learning exactly what to look for during a breast self-exam can help women to determine when a lump is benign and when it’s time for a biopsy.

Breast lumps are admittedly alarming but most are not a sign of breast cancer and they can occur for many reasons, including hormonal imbalances, pregnancy, and trauma.

In this article, we outline the differences between breast lumps and what to do if you discover one.  

What Is A Breast Lump?

A breast lump is described as a bulge, swelling, mass, or bump on the breast that feels more solid than the surrounding breast tissue.  Although synonymous with breast cancer, eight out of ten breast lumps are found to be noncancerous with the majority originating from hormonal imbalances, breast cysts, infection, or trauma. 

Typically categorized into three groups, breast lumps are considered either benign (noncancerous), precancerous, or breast cancer. Performing monthly breast self-exams is the best way to monitor any changes to your breast tissue and scheduling an appointment with your doctor to check any new lumps discovered will ensure that anything ominous is treated early. 

Recognizing Benign (Noncancerous) Breast Lumps

Benign breast lumps are generally caused by hormonal fluctuations and changes to the female body as women grow and age. Although the majority of breast lumps resulting from the aging process, pregnancy, or hormonal changes are noncancerous, they can be uncomfortable and sometimes lead to infections. We’ve listed the most common types below.  

Breast Cysts

Caused by an increase in estrogen and a drop in progesterone, breast cysts are fluid-filled sacs that grow on the breast tissue. Characterized as feeling like a small grape or a firm lump under the skin, breast cysts are common in women over the age of 30 and usually subside after menopause. 

In most cases, these benign breast lumps require no treatment, however, aspiration (fluid removal) is recommended if they become too enlarged or painful.   

Breast Fibroadenomas

Known to typically occur in women during their 20s and 30s, breast fibroadenomas are benign tumors made up of a mixture of glandular tissue and connective tissue. Usually found close to the surface of the breast skin, fibroadenomas feel round and small, however, many can be too small to feel as lumps during a breast examination and are only detected during mammograms. 

While the cause of fibroadenomas is still unknown, they are thought to be connected to reproductive hormones, sometimes increasing in size during pregnancy and shrinking after menopause. Even though the risk of breast fibroadenomas becoming cancerous is extremely rare, your doctor may recommend removing and carrying out a biopsy if a lump becomes large.  


Adenosis is a condition identified by the growth of one or more of the breast lobules, which are the mammary glands responsible for producing breast milk. Lumps associated with adenosis feel similar to breast cysts in that they are small and usually firm.

Adenosis can also cause a feeling of heaviness in the breast, as well as pain or discomfort that can resonate as far as the armpit. Because adenosis is a noncancerous condition, treatment is rarely necessary unless the lump becomes large enough to cause discomfort or pain. 


Mastitis, a condition usually limited to women who are breastfeeding, is caused when a milk duct becomes inflamed, turns into a hard lump, and leads to an infection. Symptoms include a red, hot, and swollen breast, as well as flu-like symptoms such as fever, chills, and body aches.

Several women also experience discharge from the nipple with mastitis. Lumps caused by mastitis are non-cancerous and disappear after being treated with antibiotics.

Mammary Duct Ectasia

Mammary duct ectasia is another benign (non-cancerous) condition that is associated with inflamed milk ducts, however, it is more common in women of menopausal age, as opposed to those of reproductive age.

For some women, milk ducts can widen as they age, causing the walls of the milk ducts to thicken, resulting in the duct becoming clogged with a build-up of fluid that cannot flow as usual. As well as feeling a lump under the nipple, women with duct ectasia can also experience the nipple turning inward as well as a grey-colored discharge. 

Most of the time, mammary duct ectasia will go away by itself, but if the inflammation becomes too much, doctors will prescribe antibiotics to treat it. 

Fat Necrosis

Necrosis is a medical term that refers to dead or damaged tissue. Fat necrosis occurs when the breast tissue becomes damaged due to a lack of blood and oxygen supply after an injury or trauma, such as breast surgery, seatbelt injuries, radiotherapy, or a biopsy for a previous breast lump. The damaged or dead tissue then results in hard, round lumps, skin reactions on the breast, and oil cysts. 

Although some women have reported lingering symptoms for up to 10 years, fat necrosis will normally resolve itself over time. Doctors generally prescribe over-the-counter anti-inflammatory medication to treat the pain and massaging the breast is also known to ease discomfort.  

Identifying Pre-Cancerous Breast Lumps

Pre-cancerous breast lumps are generally benign lumps that carry the risk of developing into cancerous cells at a later stage. If your doctor determines a risk, they will advise for these types of breast lumps to be surgically removed.  Below, we’ve outlined the most common type of precancerous breast lumps. 

Ductal Carcinoma in Situ & Lobular Carcinoma In Situ

Ductal carcinoma in situ is considered a non-invasive type of breast cancer mass, which means the cells lining one or more milk ducts have become cancerous, but they have not yet spread to any breast tissue. Experts estimate that approximately one out of five diagnoses of breast cancer are ductal carcinoma in situ (DCIS) and that almost all women diagnosed with these pre-cancerous cells are completely cured.    

Lobular carcinoma in situ (LCIS) is diagnosed when the cells of the breast lobule (the milk-producing glands in the breast) have become cancerous, but again, have not yet spread to any breast tissue. While this type of mass is not diagnosed as breast cancer, it is considered precancerous and will be monitored closely by your doctor.  

Intraductal Papillomas

Intraductal papillomas are small, wart-sized lumps that develop on one or more of the mammary milk ducts, typically in women aged 35-55. While the exact cause is unknown, experts believe that these lumps are a result of cells growing in the milk duct at a faster rate than usual. Although the growths are normally benign and painless, they are also known to result in discomfort and nipple discharge. 

Most cases of single intraductal papilloma are considered benign, however, when additional changes to the breast occur at the same time, such as atypical cells, an increased risk of cancer is recognized and the lump could be deemed precancerous. Intraductal papillomas that are considered precancerous are usually surgically removed along with the affected milk duct. 

Radial Scars

Radial scars are lesions or growths that look like scars when examined under a microscope. These uncommon breast growths can affect both breasts but don’t usually cause any symptoms and are sometimes only identified during a mammogram.

Although generally benign, the presence of radial scars can indicate a higher risk of cancer developing in some women. Therefore, doctors will often consider radial scars as precancerous and regularly observe them for any changes or recommend that they are surgically removed.  

Atypical Ductal or Lobular Hyperplasia 

Atypical means abnormal and hyperplasia refers to an overproduction of cells. When these words are associated with breast conditions, it generally indicates that abnormal cells are growing at a rate that may develop into breast cancer.

Both atypical ductal hyperplasia and atypical lobular hyperplasia are regarded as precancerous conditions and surgical removal is normally required to remove the growths.   

Phyllodes Tumors 

Phyllode tumors, which grow on the connective tissue of the breast are rare, accounting for less than 1% of breast tumors, and are most common in women over 40. Although most phyllode tumors are benign, doctors usually recommend for them to be surgically removed to prevent precancerous cells from developing.  

How to Know if a Lump is Breast Cancer

The physical development of breast cancer lumps can vary from woman to woman. For example, some women notice that the breast is bigger or swollen before feeling a lump, the skin on the breast can become red and warm to touch for others, but not for all. The skin of the breast can also appear dimpled or puckered, nipples can turn inward and discharge may leak from the nipple. That said, there are specific indicators to look for.

What Does a Cancerous Breast Lump Feel like?

A cancerous mass or lump in the breast is usually located in the upper outer quadrant of the breast. It usually feels hard to touch, like a stone or small pebble with uneven edges, and will not easily move around under the skin.

Sometimes the mass can be closer to the underarm than the outer quadrant of the chest, and you may recognize that it grows if left untreated. Should you notice any of the above symptoms, have your breasts examined by a doctor. 

The Most Common Types of Cancerous Breast Lumps

The most common types of cancerous (malignant) breast lumps include metaplastic breast cancer, tubular carcinoma, Paget’s disease of the nipple, inflammatory breast cancer, invasive ductal carcinoma, invasive lobular carcinoma, and medullary carcinoma.  

Diagnosing & Treating Breast Lumps

Although mammograms can provide imagery and clues about breast lumps, the only proven way to diagnose whether a breast lump is cancerous or noncancerous is by performing a biopsy. A pathologist will then examine the biopsy to determine what type of cancer it is, and what treatment is needed. 


It’s been said many times before and we’ll say it again because it’s true. Don’t let fear or worry prevent you from having a breast lump examined. It may turn out to be a noncancerous lump like a cyst, or a change in the breasts due to hormonal changes, but if it is cancerous the earlier you begin treatment the better chance you have of a full recovery.

To catch breast lumps early, conduct a monthly breast self-exam and schedule an appointment with your doctor immediately if you discover any new breast lump.  


The American Cancer Society – Recommendations For The Early Detection of Breast Cancer - https://www.cancer.org/cancer/breast-cancer/screening-tests-and-early-detection/american-cancer-society-recommendations-for-the-early-detection-of-breast-cancer.html

BreastCancer.org – Breast Self-Exam - https://www.breastcancer.org/screening-testing/breast-self-exam-bse

American Cancer Society – Radial Scars and Other Noncancerous Breast Conditions -  https://www.cancer.org/cancer/breast-cancer/non-cancerous-breast-conditions/other-non-cancerous-breast-conditions.html

American Cancer Society – Hyperplasia of The Breast - https://www.cancer.org/cancer/breast-cancer/non-cancerous-breast-conditions/hyperplasia-of-the-breast-ductal-or-lobular.html

Centers for Disease Control and Prevention – What Are The Symptoms of Breast Cancer - https://www.cdc.gov/cancer/breast/basic_info/symptoms.htm

American Journal of Obstetrics Gynecology – Inflammatory Breast Cancer – Early Diagnosis is Critical - https://www.ajog.org/article/S0002-9378%2821%2900444-0/fulltext

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