Thanks for your question. During puberty it’s common for young men to develop tissue under their nipples that feels like small breasts. The medical term for this is “gynecomastia.” It can also be caused by other things, such as medicines or hormone problems.
Gynecomastia usually feels like a small, rubbery lump right underneath the nipple(s). It is usually sore or tender when you touch it. It can affect one or both breasts. If it affects both breasts, it may affect one more than the other. Gynecomastia usually goes away on its own after several months.
If you’ve had this for a while or are concerned, it’s a good idea to speak to your health care provider.