Benign and Malignant Breast Lumps

See your doctor if you have any breast changes

In This Article

During a breast self-exam, you may notice lumps or a change in the texture of your breast. While this can make you worry, it's important to understand that not all lumps are cancerous. A lump may be malignant (cancerous) or precancerous, but there are several types of breast lumps that are benign (non-cancerous). To complicate matters, many benign breast changes can mimic breast cancer.

Breast lumps can vary in size, rate of growth, and symptoms. It is practically impossible to distinguish the cause of a lump based on a breast exam, so you should be sure to see your doctor when you first notice one.

Often, testing—mammogram, ultrasound, magnetic resonance imaging (MRI), or biopsy (when a sample of the lump is removed and examined under a microscope)—is the only way to determine what a breast lump actually is.

The following gives you a sense of the most common reasons behind breast lumps.

Waiting for the answers you need during the testing period can be challenging. Keep in mind that even if you have breast cancer, the disease is treatable, especially when found early.

what a cancerous breast lump feels like
Illustration by Brianna Gilmartin, Verywell

Benign Breast Changes

Many breast lumps turn out to be benign and will not turn into cancer or spread. Nevertheless, they can be painful or irritating, and they can cause health complications (like infections)—even if they aren't cancer.

Breast Cysts

A breast cyst is a benign fluid-filled sac in the breast tissue. They are very common and typically affect women in their 40s who are in perimenopause (the period of time before menopause when a woman stops having periods), but they can occur at any age.

A breast cyst often feels smooth and soft. If you press on a cyst, it will have some give to it, like a water balloon. A breast cyst may move around and can change in size during your menstrual cycle. Breast cysts can also be painful or tender, especially just before your menstrual period begins.

Breast cysts can be located anywhere in the breast—near the surface or deep inside. While an ultrasound or fine needle aspiration may be needed for accurate diagnosis, simple cysts are rarely linked to breast cancer.

Breast Fibroadenomas

Breast fibroadenomas are benign tumors that consist of glandular and connective tissue. They typically affect women in their 20s and 30s, but they can occur at any age.

A fibroadenoma typically feels round and 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. Some may be too small to feel and may be detected incidentally on a mammogram. 

A biopsy is needed to diagnose a fibroadenoma, and your doctor may recommend removal. Lumpectomy, radiofrequency, and a number of other fibroadenoma treatments can be used to remove the benign tumor.

While they are benign, having one is associated with an increased risk for breast cancer.

Adenosis

Adenosis is a benign condition characterized by enlargement in the lobules of the breast. Adenosis can produce a lump that feels like a cyst or a tumor. It can be accompanied by the appearance of calcifications on a mammogram.

Mastitis 

Mastitis, an infection of the breast, 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, or may cause the nipple to be retracted inward. It most commonly occurs around the age of menopause.

Fat Necrosis

When the breasts are damaged by surgery or trauma, scar tissue may develop. Fat necrosis, which feels like a hard lump, may occur. Fat necrosis may cause breast discharge and tethering of the nipple and skin. Fat necrosis can mimic cancer on imaging tests, and a biopsy is needed to tell the difference.

Oil Cysts

Breast oil cysts are fluid-filled sacs that may feel smooth and squishy. They are usually found on a self-breast exam and may be seen on mammogram, ultrasound, or breast MRI.

Caused by the breakdown of fatty tissue, they often occur after breast surgery. They are called oil cysts because they contain a liquid form of body fat.

While breast oil cysts do not become cancerous and do not increase the risk of developing breast cancer, they may occur in association with underlying cancer. They can be left alone or aspirated to remove the cyst.

Other Benign Lumps

Other benign lumps include hamartomas, breast hematomas, hemangiomas, adenomyoeptheliomas, and neurofibromas.

Keep in mind that if you have a benign lump, your risk of breast cancer—a condition that affects one in eight women— is not decreased. While you may breathe a sigh of relief upon diagnosis of a benign breast tumor, you still need to continue your regular mammograms, medical appointments, and breast self-exams.

Benign Breast Lumps and Future Cancer Risk

Women who had a history of benign breast disease are more likely to develop breast cancer than those who have never had any breast disease. According to a 2019 study in the International Journal of Cancer, benign breast disease (BBD) increases the risk of developing breast cancer in the future, in addition to the risk that a woman may already have due to family history, personal breast cancer history, or a genetic mutation.

Pre-Cancerous Breast Lumps

Several breast lumps are not cancer, but are strongly associated with an increased risk of cancer. Others are pre-cancerous growths, and the cells can transform, becoming cancer cells in the future. While most benign breast lumps are either left alone or removed for comfort, pre-cancerous lumps must be removed.

Intraductal Papillomas

Intraductal papillomas are tumors that begin in the milk ducts of the nipple and are often noted by the presence of nipple discharge. While these tumors are typically benign, they may be associated with an increased risk of cancer, particularly if there are regions of atypical hyperplasia (typically seen on a biopsy).

Radial Scars

Radial scars are an uncommon condition which can be benign, precancerous, or cancerous. They do not usually cause a palpable (something you can feel) lump but may appear as a spiky mass on a mammogram. A biopsy is usually needed, especially because cancer cells may be mixed with the radial scar.

Ductal or Lobular Hyperplasia

Atypical lobular hyperplasia and atypical ductal hyperplasia are considered precancerous conditions. In other words, these lumps are not cancer, but they can become cancerous, so they need to be treated before their characteristics change.

In Situ Tumors (LCIS and DCIS)

Ductal carcinoma in situ (DCIS) is a cancerous tumor. By definition, they are not considered invasive since they have not yet broken through the basement membrane, a layer of encapsulation that separates the cancer cells from surrounding tissue.

CIS is considered stage 0 cancer, while invasive tumors are defined as stage I to IV breast cancer.

Lobular carcinoma in situ (LCIS) is not precancerous, but it is associated with increased cancer risk.

Phyllodes Tumors 

Phyllodes breast tumors are uncommon and can be either benign or malignant. Since benign phyllodes tumors have a tendency to become malignant, benign and malignant variations are treated in the same way.

Most breast cancers begin in epithelial cells and form carcinomas. In contrast, phyllodes tumors begin in mesenchymal cells (connective tissue cells) and the tumors are defined as sarcomas.

Breast Cancer

Breast cancer is a malignancy composed of abnormal breast tissue cells. The cancer can grow in an uncontrolled way and may spread within the breast, to the lymph nodes, or to organs in distant areas of the body.

Malignant breast tumors include:

Location and Composition

Breast cancer can occur anywhere in the breast, but the most common location is the upper, outer section of the breast. It 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 (a.k.a. the "tail" of the breast).

A breast cancer lump is not typically movable during a breast self-exam, but since tissue around it may move, it's sometimes hard to know what is moving during manual examination.

A malignant breast lump may have an irregular shape (though at times it can be round) with a pebbly surface, somewhat like a golf ball. It is often hard, like a slice of raw carrot.

Diagnosis and Treatment

A clinical breast exam and a mammogram may help with the diagnosis, though sometimes an ultrasound or MRI are needed. Each of these tumor types has unique characteristics, which may be seen on imaging studies.

Even with all of these imaging studies, it may be difficult to know whether a lump is benign or malignant, and you will likely need to have a biopsy.

Mammograms miss up to 15 percent of breast cancers, especially in women who have dense breasts (a diagnosis that can only be made on imaging tests). A biopsy is the only way to distinguish between cancer and a non-cancerous condition.

The distinct characteristics of each tumor type are more definitively seen on a biopsy. There are a number of different methods for doing a breast biopsy, including a needle biopsy, core biopsy, or open biopsy, and the best option will depend on the characteristics of the tumor.

Finally, it's important to be aware that a breast biopsy usually takes cells from a small portion of a lump, which leaves the possibility of a false negative result (a normal biopsy despite breast cancer being present).

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. A biopsy will distinguish primary breast cancer from metastasis that originated elsewhere in the body.

The treatment for breast cancer depends on the stage at diagnosis and is also often targeted to the specific tumor. In addition to surgery, treatments may include chemotherapy, hormonal therapy, radiation therapy, or targeted therapies.

A Word From Verywell

Breast lumps are very common. It is important that you regularly check your own breasts for breast lumps. If you notice a lump, there is no need to panic, but it is also important that you do not ignore or postpone getting care and treatment either. Be sure to seek medical attention if you notice a breast lump—call your doctor within a few days so that you can be given a prompt appointment for imaging or an office visit.

Even benign growths generally need to be removed, treated, or carefully observed, so you will need medical attention whether you have breast cancer or not.

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