I have a golf ball sized lump on my chest as well. I showed it to my doctor and he did x-rays to see if it was just bone. It was not. I had to go get a CT Scan done to see what it was. Well, they said there was a tissue growth on top of my sternum and that it might be a tumor. I have a PET Scan on the 10th to see a little more. I'm getting a biopsy... more