There is a always a small chance (very small
in your case because you are
male and relatively young) that a
lump can be related to breast cancer. Malignant lumps are more common in an older age group, and usually aren't tender. The more likely senarios for your case are a cyst, or gynecomastia, which is an enlargment of the breast tissue. Gynecomastia is usually more central around the nipple though- but if that is the diagnosis, it is important to find out what is causing it.