A lump under the nipple is usually benign, especially if it feels like a small, rubbery disc right behind the areola. The most common explanations depend on your age and sex, but hormonal shifts are behind the majority of cases. That said, certain features of a lump do warrant prompt evaluation, and knowing what to look for can help you figure out your next step.
The Most Common Cause in Males: Gynecomastia
If you’re male and feel a firm, button-sized growth directly beneath the nipple, you’re most likely dealing with gynecomastia. This is actual breast gland tissue that develops when estrogen levels rise relative to testosterone. It can affect one side or both, and it often feels tender when pressed. About half of all adolescent boys develop some degree of gynecomastia, typically between ages 11 and 15, and it almost always resolves on its own by the end of puberty.
Gynecomastia has a second peak later in life. Roughly 65 percent of men between 50 and 80 experience it to some degree, driven by the gradual decline in free testosterone that comes with aging. So if you’re a teen or an older adult, a small lump under the nipple is an expected variation rather than something unusual.
There’s also a lookalike called pseudogynecomastia, which is simply excess fat tissue in the chest area. The key difference: pseudogynecomastia creates a general increase in breast size without a distinct lump, while true gynecomastia produces a defined, palpable disc behind the nipple.
Medications That Can Trigger Breast Tissue Growth
Dozens of medications have been linked to gynecomastia. Spironolactone, a blood pressure and heart failure drug, is one of the best-documented culprits. In studies, the effect is clearly dose-dependent: at 25 mg per day about 9 percent of men develop breast swelling, while at doses above 150 mg per day the rate climbs to 52 percent. The enlargement is typically bilateral, painless, and resolves after the medication is stopped.
Other common medications associated with subareolar lumps include finasteride (used for hair loss and prostate enlargement), certain antidepressants like fluoxetine, paroxetine, and venlafaxine, the heartburn drug cimetidine, the heart medication digoxin, and HIV antiretroviral therapy. If a lump appeared within weeks or months of starting a new medication, the timing alone is a strong clue.
Common Causes in Women
In women, the list of possibilities is broader because breast tissue is more complex, but most lumps are still noncancerous.
- Fibrocystic changes cause lumpiness, thickening, and swelling that often worsens just before your period and improves afterward. These changes are so common they’re considered a normal variation rather than a disease.
- Cysts are fluid-filled sacs that can appear suddenly and feel smooth and round. They may be tender to the touch and can fluctuate in size with your menstrual cycle.
- Fibroadenomas are solid, rubbery lumps that move easily when you push on them. They occur most often in younger women and are completely benign.
- Intraductal papillomas are small, wart-like growths inside the milk ducts. They can sometimes cause clear or bloody nipple discharge.
Breast Buds During Puberty
If your child (or you, as a young teen) has a small, sometimes tender lump under one or both nipples, it’s very likely a breast bud. In girls, breast budding is typically the first visible sign of puberty and can start anywhere between ages 8 and 13. The area under the nipple firms up, the areola widens slightly, and one side often develops before the other. This unevenness is completely normal.
In boys, as mentioned, about half will notice a similar lump during puberty. It can feel alarming, especially if it’s only on one side or is sore when bumped. These lumps typically resolve within one to two years without any treatment.
Signs of Infection or Abscess
A lump that comes on suddenly, feels warm, and is accompanied by redness or fever may be a subareolar abscess or a form of mastitis. The skin over the lump often looks swollen and inflamed, and in some cases pus drains from the area near the nipple. You might also feel generally unwell or fatigued.
Nipple piercings are a notable risk factor. Infections from piercings can appear anywhere from two weeks to over a year after the piercing was placed. Abscesses generally need drainage and antibiotics, and you should expect a follow-up within about a week to make sure the infection is resolving. If symptoms get worse before that follow-up, or if there’s no improvement after one to two weeks of antibiotics, further evaluation is important to rule out other causes.
Red Flags Worth Knowing
While most lumps under the nipple are harmless, certain features raise concern for breast cancer. In women, watch for a lump that feels hard and irregular, doesn’t move easily, or is accompanied by skin dimpling, puckering, or irritation. Redness or flaky skin on the nipple, nipple retraction (the nipple pulling inward), bloody discharge, or a change in breast shape or size are all signals that need evaluation.
In men, breast cancer is rare. The lifetime risk is about 1 in 755, and roughly 2,670 men are diagnosed each year in the United States. But it does happen, and the warning signs are the same: a hard, fixed lump, skin changes, nipple retraction, or discharge. Men over 50 and those with a family history of breast cancer carry a somewhat higher risk.
What Happens During Evaluation
If you go in to have a lump checked, the standard first step is a diagnostic mammogram combined with an ultrasound. The mammogram captures detailed images of the breast tissue, while the ultrasound helps determine whether a lump is solid or fluid-filled. If the lump turns out to be a simple cyst, the fluid can sometimes be drained with a needle during the same ultrasound appointment, which serves as both treatment and diagnosis.
If imaging reveals something suspicious, a biopsy is the next step. This involves taking a small tissue sample from the lump, guided by whichever imaging method shows the finding most clearly. The entire process, from your first appointment through biopsy results, typically takes one to two weeks.
For lumps that are clearly consistent with gynecomastia or fibrocystic changes based on history and physical exam, imaging may not even be necessary. A doctor can often diagnose these conditions by feel alone, especially in the right clinical context (a 14-year-old boy with bilateral tenderness, for example, or a woman with cyclical breast lumpiness).