Susan, I'm no doctor, and please understand that we cannot make diagnoses on this site.  Only your doctor can do that. But, as I understand it, a tumor shows up white on an X-ray, not clear. You might consider discussing with your doctor whether you have a cyst, which if it were large enough, would make your breast appear larger, and certainly you'd feel it as a lump. Even without the X-ray results, since you feel a lump, you should schedule an appointment to have it checked out. You need to set your mind at rest. So, don't panic - just make an appointment with your GP, or whichever doctor you'd go to for getting a breast lump checked. OK? Good luck - PJH