I'm a 16 year old male and I've had a hard lump in my left breast since I was 12 or 13. It's about 1 inch in diameter. My right breast doesn't have one and looks completely normal, but my left one is much bigger and the nipple is puffy. I'm wondering if it's cancerous and how I can get rid of it because it makes me look weird to have one big breast and one normal one.
If you've had it for 4 years, it's not cancer. Cancer in teens progresses a lot faster than that, unfortunately.
Many males do have a little puffiness under their nipples. If the asymmetry bothers you, surgery might be able to change it. There aren't many other options.