Breast development in boys (gynecomastia) is very common. In fact, it happens in about one-third of all males as they go through puberty, that time when a child's body begins to turn into an adult one. It is believed to be due to changing amounts of hormones in the body during puberty. Sometimes just a small bit of tissue is felt behind the nipple, while other times it feels or looks like more.
Gynecomastia can occur on one or both sides and often is more noticeable in boys who are overweight. It generally causes no physical pain, although sometimes there is some soreness in the breast, more from a teenager touching it a lot because it's new to him and he is concerned that something may be wrong.
Most cases of gynecomastia go away on their own over a few years without any treatment; patience and understanding are all that are usually needed. However, until it goes away, gynecomastia can be stressful and embarrassing for male teens. Your son may want to visit his physician, in order to be reassured that this condition is normal and nothing to worry about. If your son is overweight, his doctor also may recommend that he try to lose some weight with a healthy diet and regular exercise.
If the breast enlargement is particularly noticeable, painful, lasting longer than might be expected, causing serious emotional problems, or there is a family history of breast cancer, you should discuss this immediately with his doctor. There are some rare diseases that cause gynecomastia, but your son's physician would be able to identify other symptoms or findings of them on his physical exam.
