Why do I have a lump under one of my nipples?

Last updated on September 2, 2020


My left nipple got a lump. The lump has gotten bigger and now it looks like my left breast sticks out a bit more. Why is this?


Lumps in the breasts are not unusual for teenage boys, especially during stages 2 and 3. Nor is it unusual for one breast to stand out more than another at times — growth doesn’t always occur evenly between the left and right sides of the body.

The National Institute of Health, a U.S. government agency, notes: “Teenage boys may develop breast enlargement and lumps because of hormonal changes in mid-puberty. Although this may distress the teen, the lumps or enlargement generally go away on their own over a period of months.” [“Breast Lump“].

What is happening is that your body is storing extra fat to fuel your growth when you hit your growth spurt. A prime area for fat storage is just under the nipples, but in developing the storage sometimes lumps appear and then gradually fade away. It does mean that you probably will go through a spell where your breasts will stick out for a while until the excess fat is used up. The condition is called “gynecomastia.” It is usually temporary and fairly common among teenage boys.