I don't remember because I was diagnosed at 3 and thoroughly checked over again at 5 or 6. But I remember the little me went with a lot of x-rays, taken by a lot of blood, even checked for the possibility of Tuberculosis because I was so thin, even CT scans and MRI. Before, of course, I need a pediatrician because I was a kid, then from orthopedic or ortho surgeon, not sure, neurosurgeon, I think I also went in pulmonary a few times. Aww, those old days with my doctors. It's sad I forgot my nicknames to them. It actually depends on where you have FD, it just happens that it affected my skull so there is someone from neuro, though orthopedic is for sure will be there. The doctors will look thoroughly with your bones through scans results (I have a lot kept in the cabinet) then look for abnormalities to determine where is your FD. The group of doctors will discuss it because that's what happened to me years ago.