The doctor called my Fibrous Dysplasia a tumor. Do I have cancer, and can it become malignant?

FD is not cancer. “Tumor” simply means abnormal growth. Tumors can be malignant (cancerous) or benign (non-cancerous). Many people prefer to use the term “lesion,” generally meaning any defect, and avoid confusion with malignant bone tumors. An FD bone lesion can become cancerous, but this is rare, occurring in less than 1% of FD cases.