Looking For Advice on Dissolving Bone in Hand

Hi. I will try to make this as brief as possible. A week ago my dr. discovered the bone in my left hand is dissolving. On the x-ray, there is no obvious tumor. However, there does appear to be some type of lump around the knuckle area that you can feel, possibly just in the soft tissue. Yesterday I had an MRI. I am still awaiting the results. Bone cancer does run in my family. They have ruled out any type of arthritis or osteoporosis. They are now looking into the possiblity of bone cancer. Does anyone have any clue about this? Is there ALWAYS an obvious tumor present that would show in the x-ray if it was cancer? Can you have bone cancer, any type, without an obvious tumor but with bone dissapearing instead? THANKS for any advice you can give me. I am nervous and just looking for all possibilities while I await the MRI result. Thanks so much.