Common Breast Lumps That Aren’t Cancer

MSK technician Jennifer Moreta helping give a mammogram.

A breast lump should always be checked out by a doctor, who may recommend diagnostic imaging such as mammogram and breast ultrasound. (Pictured: Jennifer Moreta, mammography technologist at the MSK Ralph Lauren Center.)

What should you do if you notice a lump in your breast? Don’t panic. See your doctor.

“Many lumps turn out to be benign,” says Memorial Sloan Kettering Cancer Center breast radiologist Kimberly N. Feigin, MD, Acting Chief of Breast Radiology at MSK. “But the most important thing is to not ignore it. Get it checked out.”

The earlier breast cancer is caught, the easier it is to treat.

What Can a Benign Breast Lump Feel Like?

Lumps that are benign (not cancer) may be tender and feel smooth and mobile. A cancerous lump is more likely to feel hard, but some non-cancerous lumps can feel hard, too.

MSK breast expert Kimberly Feigin

Dr. Kimberly Feigin

Dr. Feigin recommends seeing a doctor about any new breast lump — no matter how big or small it is. That’s true even in someone who recently had a negative mammogram. But, she adds, keep in mind that the lump could very well be one of the following:

A Cyst

Cysts are fluid-filled sacs that usually don’t require treatment but can be drained if they are large and cause discomfort. Sometimes they are sensitive to the touch; other times they are barely noticeable. They tend to wax and wane with a woman’s menstrual period and may go away on their own.

“A cancerous lump will not change with your menstrual cycle,” Dr. Feigin says.

Cysts are quite common in young women but can occur in women of all ages. In women under 30, doctors often use ultrasound to evaluate lumps — a mammogram usually isn’t warranted.

A Fibroadenoma

Fibroadenomas are clumps of benign breast tissue that come together and form a mass. These breast masses may feel firm but are usually moveable. They are common and usually found in women younger than 50. Some present as lumps, while many are found incidentally on breast imaging such as mammography or ultrasound. As with cysts, fibroadenomas usually don’t require any treatment.

Because it looks solid (as opposed to filled with fluid) on an ultrasound, a woman may sometimes need a biopsy to confirm the lump is a fibroadenoma. But this may not always be necessary because a fibroadenoma has certain benign characteristics that can be well seen on an ultrasound.

“You can draw a smooth line around the edges of a fibroadenoma, which is typically oval-shaped and oriented parallel to the chest wall,” Dr. Feigin says. “With cancer, the margins tend to be more irregular, and cancers typically have increased blood supply.”

Pseudoangiomatous Stromal Hyperplasia (PASH)

PASH is a benign mass caused by an overgrowth of benign cells found in connective tissue and smooth muscle. It is influenced by hormones and in rare cases may cause breast enlargement. It can feel like a lump, but most of the time a person doesn’t even feel it; it just shows up on routine imaging or is found incidentally on a breast biopsy. It is most often found in younger women between the ages of 30 and 50. However, cases in girls as young as 14 have been documented. Even though it has a long, scary name, PASH is harmless and usually does not require treatment unless it is large and causing discomfort.

Lumpy Breast Tissue

Sometimes what feels like a lump is just dense breast tissue or a ridge of breast tissue. Regular breast self-exams can help women familiarize themselves with their breasts, Dr. Feigin says. Menstruating patients should examine themselves about seven days after starting their period every month.

Fat Necrosis (Scar Tissue)

Fat necrosis develops when an area of fatty breast tissue gets injured, whether through breast surgery or trauma, like a car accident or bad fall. It can feel like a firm lump. “We commonly see it after surgery in patients who have had lumpectomies, breast reduction surgery, or mastectomies,” Dr. Feigin says.

A Reaction to the COVID-19 Vaccine or Other Vaccines

Dr. Feigin says she sees people who have thickened lymph nodes in the armpit of the arm where they have received a vaccine. It happens most often when a person’s breast screening is close to when they were vaccinated. “We will do an ultrasound to check it,” Dr. Feigin says, “and we can usually tell that it’s a benign lymph node.” Sometimes a follow up ultrasound of the lymph node is performed a few months after the initial scan. A benign reactive lymph node will typically return to normal size over time.

However, Dr. Feigin notes, people should not assume a lump under the armpit is from a vaccine, so it’s still important to get it checked out. It is also extremely important to not skip your routine screening or delay it too long on account of any vaccine. Simply inform the technologist performing your mammogram when you received the vaccine and which arm.

Are moveable breast lumps cancer?

Moveable breast lumps are usually not cancer. More often, they are fibroadenomas or cysts. While moveable breast lumps are often benign, they still should be checked by a doctor. Most breast cancers start out as moveable lumps in their early stages, so it is important to consult with an expert to rule out cancer.

Are painful breast lumps cancer?

Usually not. Most painful breast lumps are caused by benign conditions such as cysts, fibroadenomas, or hormonal changes. However, as with movable lumps, you should have any breast lump evaluated by an expert to determine the cause.

Does the size of a breast lump determine whether it is breast cancer?

The size of a breast lump alone does not determine if it is breast cancer. Breast cancer can appear as small or large lumps. The size of the lump also does not indicate the cancer stage or severity, although larger lumps may sometimes be more advanced tumors. Regardless of size, any new breast lump should be examined by an expert.

Breast Cancer Imaging at MSK

A physical exam alone cannot reliably distinguish a benign lump in the breast from a suspicious one, so a diagnostic imaging evaluation is warranted.  This usually entails a mammogram and breast ultrasound. Sometimes additional testing may also be needed.

Breast Cancer Screening at MSK

For women without lumps or other symptoms, we offer breast cancer screening services and programs for people at all levels of risk, with or without a history of cancer. MSK’s breast cancer screening guidelines recommend that most women get a mammogram every year beginning at age 40, with annual mammography beginning earlier for women at a high risk for breast cancer. Some imaging tests that we use for screening, depending on a patient’s breast density and level of risk, include:

  • A tomosynthesis (“3-D”) mammogram offers a detailed look at the breast in “slices” — almost like a photo flipbook.
  • An ultrasound (also known as a sonogram) uses sound waves to see masses. It can distinguish between solid and cystic masses and is often used for screening women with dense breast tissue on a mammogram.
  • A contrast mammogram and an MRI both show if the mass has blood flow. Cancers typically have increased blood supply.



Key Takeaways
  • Most breast lumps are not cancer.
  • The only way to tell if a breast lump is benign is by getting it checked out.
  • MSK offers various screening services for all people, with or without a history of cancer.