Clinical and radiographic progression of fibrous dysplasia: cystic change or sarcoma? Description of a clinical case and review of the literature.

The clinical and radiographic progression of fibrous dysplasia may be due to a cystic-hemorrhagic change, or to a sarcomatous transformation. The distinction between these two possibilities, which is essential to treatment, depend on the biopsy. A case of fibrous dysplasia in a female aged 18 years is described in which, 3 years after pathologic fracture consolidated with non-surgical treatment, clinical and radiographic progression occurred, enough to suspect malignant transformation. Histological diagnosis showed fibrous dysplasia with a cartilaginous component and cystic-hemorrhagic changes, and curettage-bone allografting resulted in healing of the lesion.