Most breast lumps are not cancer. Of all breast lumps that undergo biopsy, about 80% turn out to be benign. That statistic doesn’t mean you should ignore what you’re feeling, but it does mean the odds are strongly in your favor. The cause is usually a cyst, a fibroadenoma, hormonal breast tissue changes, or another non-cancerous condition.
The Most Common Benign Causes
Several types of harmless lumps can develop in breast tissue, and each one feels slightly different.
Cysts are fluid-filled sacs that form inside the breast. They’re most common in premenopausal women and in those taking hormone therapy during menopause. Cysts can be painful, especially right before your period starts, and their size may fluctuate throughout your cycle. Some are too small to feel at all, while others are large enough to notice easily.
Fibroadenomas are the most common benign breast tumors in women under 30. They typically feel like hard, round lumps that move easily when you press on them. They don’t usually hurt. Fibroadenomas can grow larger during pregnancy or while taking hormone therapy (when estrogen levels rise) and may shrink after menopause.
Fat necrosis causes round, firm, usually painless lumps. It develops after an injury to the breast, surgery, or radiation therapy. The skin around the lump may look red, bruised, or dimpled, which can be alarming, but the condition itself is not cancerous.
Hormonal Changes and Lumpy Breast Tissue
Fluctuating hormones during your menstrual cycle can make your breasts feel lumpy, tender, and swollen. This is sometimes called fibrocystic breast changes, and it’s considered normal. The lumpiness often has a ropelike texture and tends to worsen from mid-cycle (around ovulation) through the days just before your period, then improves once bleeding starts. Breast nodules tied to your cycle typically change in size month to month.
The best time to check whether a lump is truly persistent or just cyclical is about one week after your period begins, when breast tissue is least engorged. If a lump appears at the same time every month and resolves after your period, hormonal changes are the likely explanation.
Infections Can Feel Like Lumps Too
Mastitis, a breast infection most common during breastfeeding, can create a firm, swollen area that feels like a mass. It’s usually accompanied by warmth, redness, tenderness, and sometimes fever or flu-like symptoms. A breast abscess, which is a pocket of pus that can develop from untreated mastitis, may also feel like a distinct lump. These infections need treatment, typically antibiotics, but they aren’t cancerous.
Signs That Need Prompt Attention
Certain features make a breast lump more concerning. The Mayo Clinic recommends having a lump evaluated if it’s new and feels firm or fixed in place, if it doesn’t go away after four to six weeks, or if it changes in size or texture over time.
Beyond the lump itself, watch for these additional warning signs:
- Skin changes on the breast: dimpling, puckering, crusting, or redness
- A nipple that has recently turned inward
- Nipple discharge (especially bloody discharge) that isn’t breast milk
- Thickening or swelling of part of the breast
- A new lump in the armpit, or an armpit lump that’s growing
- A change in the size or shape of one breast
None of these signs guarantee cancer. Fat necrosis, for instance, can cause skin dimpling. But any of them warrants a professional evaluation rather than a wait-and-see approach.
What Happens at the Doctor’s Office
The evaluation process depends largely on your age and whether you’re pregnant. For women under 30 or those who are pregnant, the first step is usually an ultrasound. Its primary job is to determine whether the lump is filled with fluid (a cyst) or solid. That single distinction narrows the possibilities significantly.
For women 30 and older who aren’t pregnant, a diagnostic mammogram is typically ordered first. This is different from a routine screening mammogram because it focuses specifically on the area of concern. Importantly, 10 to 20 percent of breast cancers that you can feel by hand don’t show up on a mammogram, so an ultrasound is often ordered alongside it even if the mammogram looks normal.
After imaging, your radiologist assigns a score using a standardized system called BI-RADS, which ranges from 0 to 6. A low score means the finding is almost certainly benign. A higher score (4 or 5) means there’s enough concern to recommend a biopsy, where a small sample of tissue is removed with a needle and examined under a microscope. A BI-RADS score is not a diagnosis on its own. It’s a way for the radiologist to communicate their level of concern and recommend next steps.
What Each Result Typically Means for You
If imaging shows a simple cyst, it’s benign. It only needs to be drained if it’s causing you pain or pressure, and the follow-up is usually just a routine exam in a year. A complicated cyst (slightly unusual features but no solid components) has less than a 1% chance of being malignant. Your doctor may recommend monitoring it with repeat imaging every 6 to 12 months, or they may suggest sampling it with a needle right away.
If imaging identifies a solid mass that looks likely benign, such as a fibroadenoma, the typical plan is repeat imaging every 6 to 12 months for one to two years to confirm it stays stable. A solid mass that looks suspicious goes straight to biopsy.
Breast Lumps in Men
Men can feel breast lumps too, and the most common cause is gynecomastia, an enlargement of breast tissue driven by a hormone imbalance between testosterone and estrogen. It typically feels like a button-sized growth directly beneath the nipple that may be tender to the touch and moves easily. Gynecomastia can be triggered by certain medications (including some heartburn drugs, blood pressure medications, and hair loss treatments), liver or kidney disease, thyroid problems, or simply by weight gain, which increases fatty tissue in the chest.
Male breast cancer is far rarer than gynecomastia but does occur. A lump that feels fixed, is located away from the nipple, or is accompanied by skin changes or nipple discharge should be evaluated to distinguish between the two.