X ray of broken bone showed hole in bone biopsy done and was neg for bone cancer. recent blood test showed low white blood count. reason for concern?

Need more info: "hole in bone" could be many things. Because of low white blood cells, I am worried about the bone marrow and , if not done, should be biopsied. (not sure if that's what was biopsied from your note) other blood tests should also be done.

Evaluation warranted: Depending on how low the white count, it would be wise to continue to be followed by a primary health care provider and/or hematologist. It will likely return to normal, but it should be followed.