My 17 year old son was diagnosed with fibrous dysplasia two years ago when he broke his arm (humerus). He had a rod inserted down his arm from his shoulder. Without this, the doctors say his arm would break again due to the cyst. The doctors monitor the cyst yearly for change. I'm interested to know what the chances of there being any change in a humerus cyst are? Will there ever be a time in his life that this will not have to be monitored?