In short
- Gynecomastia on one side only is common, especially at first, and usually benign.
- Tenderness or pain generally signals recent, active gynecomastia: the best time for medical treatment.
- Male breast cancer exists but is rare (around 1% of breast cancers). It mainly affects men over 60.
- Warning signs: a hard, irregular, off-centre or fixed lump, bloody discharge, an inverted nipple, skin changes, a lump in the armpit.
- The examination is simple: feeling the area, then if needed an ultrasound and a mammogram, rarely a biopsy.
Finding a lump under your nipple, especially on one side only, often triggers instant worry. It needs putting in perspective. In the vast majority of cases, it is gynecomastia, a benign enlargement of the gland. But a few signs should not wait. Here is how to tell the difference, and what happens at the examination.
One-sided gynecomastia is common
The two breast glands respond to hormones independently. So it is common for gynecomastia to:
- start on one side and only appear on the other months later;
- stay asymmetric, with one side larger;
- be strictly one-sided, which happens both in teenagers and adults.
In a teenager with a normal examination, one-sided gynecomastia is monitored just like gynecomastia on both sides. In adults, and especially after 40, a medical examination is recommended, simply to make sure it is gland and not something else.
Why it hurts
Pain or tenderness is typical of the active phase, the first few months. The gland is growing, the tissue is inflamed and reacts to the slightest friction. After about a year, the tissue becomes fibrous: less sensitive, but also much less likely to shrink.
Painful gynecomastia is therefore often recent. That is precisely when medical treatment is most likely to work. All the more reason to see a doctor now rather than in a year. See treatment without surgery.
Meanwhile, for relief:
- a fitted garment or a light compression vest limits friction;
- a plaster or nipple cover protects the nipple during sport;
- avoid feeling the area every day to “check”: handling it keeps it sensitive.
Other kinds of pain have other causes: sudden pain with redness, warmth or fever suggests an infection (mastitis or abscess), rare in men but possible. It needs prompt medical attention.
Signs that mean you should see a doctor promptly
These signs do not mean “cancer”. They mean “get it examined without waiting”. The vast majority of male breast lumps, even in this context, turn out to be benign.
Gynecomastia or cancer: the differences
| Gynecomastia | Male breast cancer | |
|---|---|---|
| How common | Very common | Rare |
| Age | Any age, peaks at puberty and after 50 | Mostly after 60 |
| Side | One or both | Almost always one |
| Position | Centred under the areola | Often off-centre |
| Feel | Firm, rubbery, mobile | Hard, irregular, sometimes fixed |
| Pain | Common when recent | Usually painless |
| Nipple, skin | Normal | Sometimes inversion, discharge, ulceration |
Male breast cancer accounts for about 1% of breast cancers. It mostly occurs around the age of 65–70. Known risk factors are a BRCA2 gene mutation, a family history of breast or ovarian cancer, Klinefelter syndrome, radiation to the chest, obesity and liver disease. As in women, the earlier it is found, the better it is treated.
How the examination works
- Questions: since when, how it has changed, pain, discharge, medicines, family history.
- Feeling both breasts, the armpits and the testicles. The doctor notes the size, consistency, position and mobility of the lump.
- A breast ultrasound, if doubt remains: it distinguishes gland, fat and any nodule.
- A mammogram, as a complement, if there is a suspicious sign or in older men.
- A biopsy, only if imaging shows a lesion that does not look like gynecomastia: a needle sample under local anaesthetic, for analysis.
Depending on the context, blood tests look for the cause of the gynecomastia (see the causes).
Other causes of a breast lump in men
More rarely, a lump in the breast area can be:
- a lipoma (a benign fatty lump, soft and mobile);
- a sebaceous or epidermal cyst, often attached to the skin;
- a haematoma after a knock;
- a lymph node;
- an infection (abscess);
- exceptionally, another tumour.
An ultrasound usually tells them apart in a few minutes.
The bottom line
A lump under the nipple in a man is almost always gynecomastia, and gynecomastia is not cancer. A simple appointment with your GP is enough to confirm it, and to free you from needless worry. It is nothing to be embarrassed about. Doctors see this every day.
