SPONTANEOUS MALIGNANT TRANSFORMATION OF FIBROUS DYSPLASIA

Objective. To evaluate the clinical and radiological findings in diagn osing spontaneous malignant transformation of fibrous dysplasia. Metho ds. Fifteen cases of sarcomatous transformation proved by operation an d pathological examinations were found in a group of 356 patients with fibrous dysplasia, and their radiological manifestations were retrosp ectively studied. The 15 cases included 8 osteosarcomas, 5 fibrosarcom as and 2 chondrosarcomas. All the 15 patients were known to have long- standing fibrous dysplasia, but no radiation therapy was ever received . Eleven patients had polyostotic fibrous dysplasia and 4 had monostot ic type. Results. Malignant transformation most frequently occurs in t he cystic expansive lesion of the long tubular bone. Pains, swelling a nd late appearance of a bony mass are the main clinical manifestations . The early radiological features of sarcomatous transformation in fib rous dysplasia are moth-eaten or cystic areas of osteolysis located in the involved bone. The cortical destruction and gradual formation of a soft tissue mass that contains tumor-bone are highly suspicious of o steosarcomatous transformation, while ring-like and spotty calcificati on in the tumor matrix is indicative of chondrosarcoma. Fibrosarcoma u sually shows simple osteolytic destruction. Conclusions. According to the clinical radiological findings, patients of sarcomatous transforma tion can be detected in the early stage. These radiological findings m ay be used as a due for differentiating various kinds of sarcomatous t ransformation.