The Basics on Benign and Cancerous Breast Lumps

See your doctor if you have any breast changes

Computer rendering of breast cancer
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During a breast self-exam, you may notice lumps or a change in your breast texture. While this can be terrifying, it's important to understand that not all lumps are cancerous.

Still, if you do find a lump, it's vital to see your doctor right away. This is because it can be difficult to determine whether a lump is benign or malignant, and often the only way to know for certain is through further tests like a mammogram or even a biopsy (where a sample of the lump is removed and looked at under a microscope).

While you may be anxious to take these steps to figure out what is going on in your breast, keep in mind that even in the worst case scenario of breast cancer, most tumors are very treatable, especially when found early. 

Let's take a look at a few of the more common types of benign (non-cancerous) breast lumps, as well as worrisome signs and symptoms of cancerous breast lumps. 

Basics on Breast Cysts

A breast cyst is a benign (harmless) fluid-filled sac which can grow right within the breast tissue. Breast cysts are very common and rarely linked to breast cancer. They are most common in women in their 40s who are in perimenopause (the period of time before menopause when a woman stops having periods), but they can occur really at any age.

Composition of a Breast Cyst

A breast cyst often feels smooth and squishy. In other words, if you are pressing on a cyst, it will have some give to it, like a water balloon.

Furthermore, a breast cyst may move around and can change in size during your menstrual cycle.

Breast cysts can also be painful if they are large and are pressing on a tender area. That said, you may only feel them or feel pain from them just before your menstrual period begins.

Location of Breast Cysts 

Breast cysts can be located near the surface, or deeper inside, close to your chest wall. If the cyst is closer to the surface, it is easy to find and easy to distinguish from other lumps. However, if it is deeper inside, it's more difficult to distinguish it from other kinds of breast lumps, because when you press on it, you're actually trying to work through layers of breast tissue, which may be dense and firm.

Diagnosing a Cyst

Cysts cannot be diagnosed by a clinical breast exam or mammogram alone. Instead, a doctor will probably order a breast ultrasound, since the sound waves pass right through fluid-filled cysts, as opposed to bouncing back in solid lumps. In the case of solid cysts, more tests, such as a biopsy may be needed. 

In the case of a fluid-filled cyst, a doctor may also take a sample of the cyst fluid by performing a fine needle aspiration with a syringe. This procedure removes the fluid from inside the cyst. If the cyst deflates with aspiration and the fluid is non-bloody, this is a benign breast cyst. 

Basics on Breast Fibroadenomas

Breast fibroadenomas are benign tumors consisting of glandular and connective tissue and are most commonly found in women in their 20s and 30s, but they can occur at any age.

While fibroadenomas themselves are benign, they do increase a women's risk of developing breast cancer in the future, about one and a half times (or more) than a woman with no changes in her breast. 

Fibroadenoma Composition and Location

A fibroadenoma will feel like a round breast lump and is often quite firm. It can usually be moved around beneath the skin during a breast self-exam. 

Fibroadenomas are often located near the surface of the breast and are then easily felt, although some may be too small to be felt. In this instance, a fibroadenoma may be incidentally found on a mammogram. 

Fibroadenoma Diagnosis and Treatment

A biopsy is needed to diagnose a fibroadenoma; however, even with a biopsy, your doctor may recommend removal of the fibroadenoma to be absolutely certain there is no breast cancer (and if there is, to treat it, of course). In addition to a lumpectomy, radiofrequency ablation is sometimes used to treat a fibroadenoma. 

Basics on Other Breast Lumps

There are many other conditions which may cause a benign, precancerous, or cancerous breast lumps. Some of these include:

Ductal or Lobular Hyperplasia

Atypical lobular hyperplasia and atypical ductal hyperplasia are conditions which are considered precancerous. In other words, these lumps are not cancer, but significantly increase the risk that you could develop breast cancer. 

Lobular Carcinoma In Situ (LCIS) and Ductal Carcinoma In Situ (DCIS)

Both LCIS and DCIS are cancer, but since the tumors have not yet broken through something known as the "basement membrane," they are not considered invasive. (Stage I to IV of breast cancer are all considered invasive). Carcinoma in situ is considered stage 0 cancer.

Adenosis

Adenosis is a benign condition in which there is enlargement in the lobules of the breast. Adenosis can cause a lump that feels like a cyst or a tumor and is sometimes hard to distinguish from cancer since it usually causes calcifications on a mammogram.

Phyllodes Tumors 

A phyllodes breast tumor is an uncommon tumor that can be either benign or malignant. Since benign phyllodes tumors have a tendency for becoming malignant, these tumors are treated in much the same way. Most breast cancers begin in cells called epithelial cells which form carcinomas. In contrast, phyllodes tumors occur in mesenchymal cells (connective tissue cells) and the tumors are actually sarcomas.

Intraductal Papillomas

Intraductal papillomas are tumors which begin the in the milk ducts of the nipple and are most often noted by the presence of nipple discharge. While these tumors are most often benign, if they have regions of atypical hyperplasia, they may be associated with an increased risk of cancer.

Fat Necrosis and Oil Cysts 

When the breasts are damaged by surgery or trauma, scar tissue may develop. Fat necrosis may occur which feels like a hard lump, or instead, benign oil cysts may occur.

Mastitis 

An infection of the breast, mastitis is often accompanied by redness, swelling, and pain. Sometimes it may be difficult to distinguish between mastitis and inflammatory breast cancer, which usually begins with redness, tenderness, and a rash, rather than a lump.

Duct Ectasia

Mammary duct ectasia is a benign condition in which the milk ducts become clogged and swollen, often causing a grayish discharge. It may cause a small lump just under your nipple, and sometimes cause the nipple to be retracted inwards. It is most common in women who are around the age of menopause.

Radial Scars

Radial scars are an uncommon condition which can be benign, precancerous, or cancerous. They do not usually cause a lump that you can feel but may appear as a lump on a mammogram.

Other Benign Breast Changes

Lipomas or other benign tumors or lumps include hamartomas, breast hematomas, hemangiomas, adenomyoeptheliomas, and neurofibromas.

Metastatic Cancer

On rare occasions, metastases from cancers in other regions of the body, such as colon cancer or lung cancer, may give rise to a new breast lump.

Basics on Breast Cancer

Breast cancer is a malignant lump that is made of abnormal breast tissue cells, growing in an uncontrolled way that may spread to the adjacent tissues or other organs.

Composition and Location of Breast Cancer

A malignant breast lump will have an irregular shape (though at times it can be round) with a pebbly surface, somewhat like a golf ball. It is often very hard, like a slice of raw carrot. It may not be movable during a breast self-exam, but since tissue around it may move, it's sometimes hard to know if the lump is moving or if healthy tissue around it is moving. Most often breast cancer is painless, though breast cancer can sometimes cause breast pain, so whether or not a breast lump is tender cannot confirm a diagnosis.

Breast cancer can be located near the surface or deeper inside the breast, close to the chest wall. It can also occur in the armpit area, where there is more breast tissue (the "tail" of the breast).

Breast Cancer Diagnosis and Treatment

A clinical breast exam and a mammogram may help with the diagnosis, though sometimes an ultrasound or MRI are needed. Even with all of these imaging studies, it may be difficult to know whether a lump is benign or malignant. A biopsy is most often needed to provide more information about the lump and is the only way to distinguish between cancer and a non-cancerous condition.

The treatment for breast cancer depends on the stage at diagnosis. In addition to surgery, treatments may include chemotherapy, hormonal therapy, radiation therapy, targeted therapies, or newer medications, which are being studied in clinical trials.

A Word From Verywell

In the end, only a breast biopsy can distinguish between a cancerous lump or tumor versus a benign breast lump or tumor. Also, it's important to note that certain benign breast conditions—like papillomas or atypical hyperplasia—may increase a woman's risk of developing breast cancer in the future. 

Sources:

American Cancer Society. Fibroadenomas of the Breast. 

Larribe, M., Thomassin-Piana, J., and A. Jalaguier-Coudray. Breast Cancers with Round Lumps: Correlations Between Imaging and Anatomopathology. Diagnostic and Interventional Imaging. 2014. 95(1):37-46.

Lehman, C., Lee, A., and C. Lee. https://www.ncbi.nlm.nih.gov/pubmed/25341156. AJR American Journal of Roentgenology. 2014. 203(5):1142-53.

Valeur, N., Rahbar, H., and T. Chapman. Ultrasound of Pediatric Breast Masses: What to do with Lumps and Bumps. Pediatric Radiology. 2015. 45(11):1584-99.

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