8 Causes of Breast Lumps That Aren't Cancer

More often than not, the culprit behind your lumps and bumps isn't cancer. So what's really going on with your breasts?

In the final season of Sex and the City, confident-as-hell Samantha Jones is at a consultation for a breast augmentation when her plastic surgeon discovers a lump. “You’re kidding...it’s not serious, right?” she asks. And though the doctor reassures her that it’s probably just a cyst, the ever-fierce Samantha is visibly worried about her health. (After all, a lump in the breast is one of most noticeable signs of breast cancer.)

Despite the exaggerated love triangles and drama that SATC is known for, Samantha’s situation isn’t too far from reality: eight in 10 women develop lumps in their breasts at some point, says Sherry A. Ross, M.D., F.A.C.O.G, author of She-ology and She-ology: The She-quel. Although Samantha’s lump turned out to be cancerous, most breast lumps are caused by other medical conditions, according to the Centers for Disease Control and Prevention.

In fact, lumps in the breast can stem from something as simple where you are in your menstrual cycle. In the days leading up to your period, estrogen and progesterone levels can fluctuate causing an increase in the nodularity (aka lumpiness) of breast tissue. This can result in temporary benign cysts, says Dr. Ross. “If you feel a breast lump just before your period, chances are it will go away once you finish your period,” she adds. And just like chest size can vary, so can your level of lumpiness. (Your breasts may even sag more than others—and that's A-OK.)

Reasons like this underscore why it’s so important to become familiar with your breast tissue and your “normal,” says Dr. Ross. She recommends performing a a breast self-exam on a monthly basis. ICYDK, a self exam should include both feeling and looking at your breasts. Do it in the four-day window right after your period ends, once the hormonal effects on breast tissue have subsided. When you’ve established a mental roadmap of the usual lumps and bumps, you’ll be able to detect any out-of-the-ordinary characteristics. “Early detection can be lifesaving when it comes to abnormal changes in breast tissue,” says Dr. Ross. “You always have to be your best advocate when it comes to your health, especially your breast health.”

If you notice a lump in your breast that isn’t going away or a bump that feels like a peanut M&M (the typical shape and size of the majority of benign muscle tumors or breast cysts), go ahead and book an appointment with your doctor for an exam. They'll determine if further testing, like a breast ultrasound, is necessary, says Dr. Ross. Even if your breasts feel lump-free, experiencing fevers and noticing changes in the size, shape, or appearance of your breasts (such as dimpling, puckering, swelling, redness, or darkening of the skin) are all be reasons to meet with your healthcare provider as well, she adds. All in all, if you’re experiencing breast changes that worry you, there’s no harm in scheduling that check-up. (

So if cancer isn’t typically the culprit, what can cause a seemingly random lump in the breast? Here, the medical conditions that could be the reason behind unwelcome bumps.

Non-Cancerous Medical Conditions That Can Cause Breast Lumps

1. Cysts

Cysts are one of the most common causes of lumps in breasts, according to the CDC. They’re often found in women beginning in their 40s and women taking menopausal hormone therapy. Cysts in the breast begin to develop when fluid builds up inside the breast glands. These can result in small, fluid-filled sacs that typically feel like round, movable lumps, though some may be too small to palpate, according to the American Cancer Society. Thanks to changes in your hormone levels, cysts can increase in size and feel more painful in the days before your period. (BTW, you can get a cyst on your ovaries too.)

Your doctor will likely perform an ultrasound to see what the cyst is made of. Cysts filled only with fluid (called a simple cyst) normally aren’t a cause for concern and don’t need to be removed unless they bother you. If you have a complex cyst, which contains solid components, a biopsy may be needed to rule out cancer, according to the American Cancer Society.

2. Fibrocystic Breast Condition (aka Fibrosis or Fibrocystic Breast Disease)

Fibrocystic breast condition is another top cause of lumps in breasts, according to the CDC. The condition is identified by benign changes in breast tissue and typically affects women younger than 45, and those undergoing hormone replacement therapy. Along with having dense tissue, “fibrocystic breasts are classically lumpy, round or oval, and tender, [with the condition] occurring in one or both breasts,” says Dr. Ross.

As many as half of all women experience fibrocystic breast changes—symptoms of the condition—at one point in their lives, which can include breast pain, lumps in the breast, and sensitive, itchy nipples right before or during your period, according to the National Cancer Institute. Fibrocystic breast changes are usually left untreated, but taking pain medication and applying heat or ice compresses can help ease symptoms. Even more good news: Fibrocystic breast condition doesn't increase your risk of developing breast cancer, per the National Cancer Institute.

3. Fibroadenomas

Fibroadenomas—benign tumors that feel like round, hard lumps in the breast—are the most common non-cancerous tumor affecting women under 30 years old, according to the National Cancer Institute. These marble-like, often-painless growths are made of breast lobules (aka the milk-producing glands) and connective tissue. A biopsy is usually done to ensure they’re not part of a more serious condition. Your doctor may recommend removing a fibroadenoma if it continues to grow or if it changes the shape of the breast, according to the American Cancer Society. However, most can be followed yearly without surgical intervention and some even shrink on their own, says Dr. Ross.

4. Adenosis

Often found in biopsies of women who have fibrocystic breast condition or cysts, adenosis occurs when breast lobules are enlarged and there are more glands than usual. When the lobules are close together, they may feel like a lump in the breast. In these cases, it might be difficult to discern adenosis from cancer, especially if mineral deposits develop, so your doctor may perform a biopsy. Luckily, this condition doesn’t need to be treated unless it's causing discomfort, according to the American Cancer Society.

5. Fat Necrosis

Following breast surgery, radiation therapy, or an injury, your body will start repairing any damaged fatty breast tissue. In some cases—usually when women have large breasts—fat necrosis occurs. This means the breast tissue is replaced with a cyst or scar tissue, causing a round, firm, and usually painless lump in the breast, according to the National Cancer Institute. While the skin around the lump may look red, bruised, or dimpled, fat necrosis usually doesn’t need to be treated unless the lump in the breast gets bigger or becomes uncomfortable, according to the American Cancer Society.

6. Intraductal Papillomas

Most commonly affecting women 35 to 55 years old, these benign, wart-like tumors grow inside the breast milk ducts, usually close to the nipple. The growths can be painful, lumps in the breast (typically behind or next to the nipple), and clear, sticky, or bloody discharge from the nipple, per the National Cancer Institute. Your doctor will likely perform a biopsy to diagnose the growth, and surgery is usually needed to remove the papilloma and the part of the duct it’s in, according to the American Cancer Society. If you have multiple intraductal papillomas, your breast cancer risk may increase slightly, according to the National Cancer Institute. Right now, there aren't any known causes or risk factors for intraductal papillomas themselves.

7. Duct Ectasia

Most commonly found in women approaching menopause, this benign breast condition develops when a milk duct in the breast thickens and becomes blocked with fluid. Experts haven't pinpointed the exact cause, but changes in breast tissue due to aging could play a role: As the breast changes from mostly glandular to mostly fatty tissue, the milk duct could become blocked. Other possible risk factors include smoking, which can widen milk ducts and lead to inflammation and inverted nipples, which in turn might obstruct the ducts, according to the Mayo Clinic.

The condition doesn't always display symptoms, but nipple discharge, tender or red nipples, and inverted nipples can occur, per the National Cancer Institute. If the blocked duct becomes infected or there's scar tissue around the duct, it may develop into a hard lump—which can be confused with cancer, according to the American Cancer Society. If a lump develops, a biopsy may be needed to rule out cancer, but duct ectasia can typically go away without treatment. In the meantime, your doctor may recommend taking pain medicine, applying a warm, wet cloth to your breast, and using breast pads for nipple discharge.

8. Mastitis

Breastfeeding women may experience mastitis, an inflammatory condition that develops when a milk duct becomes blocked and infected. The breast might look red and feel warm, tender, and lumpy, and you might experience flu-like symptoms, according to the National Cancer Institute. The condition is typically treated with antibiotics and by draining any milk from the breast, according to the American Cancer Society.

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