My teenage son 14 years has been complaining from a lump in one breast beside the nipple for more than one year now. the doctor said that it will go away and it is most probably gynecomastia but so far it is still there.what could it be ?

Gynecomastia at the time of puberty is fairly common but it is harmless. It is usually present in both breasts. It usually affects the whole breast. If your son has a lump located away from the nipple, it could be a fibroadenoma which is also benign condition. Unless this lump is growing in size, it can be observed under the care of a physician. Have him checked by your family doctor. Best wishes.