OBJECTIVE: To evaluate the clinical and radiological findings in diagnosing spontaneous malignant transformation of fibrous dysplasia. METHODS: Fifteen cases of sarcomatous transformation proved by operation and pathological examinations were found in a group of 356 patients with fibrous dysplasia, and their radiological manifestations were retrospectively studied. The 15 cases included 8 osteosarcomas, 5 fibrosarcomas 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 monostotic type. RESULTS: Malignant transformation most frequently occurs in the cystic expansive lesion of the long tubular bone. Pains, swelling and late appearance of a bony mass are the main clinical manifestations. The early radiological features of sarcomatous transformation in fibrous 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 osteosarcomatous transformation, while ring-like and spotty calcification in the tumor matrix is indicative of chondrosarcoma. Fibrosarcoma usually shows simple osteolytic destruction. CONCLUSIONS: According to the clinical radiological findings, patients of sarcomatous transformation can be detected in the early stage. These radiological findings may be used as a clue for differentiating various kinds of sarcomatous transformation.
OBJECTIVE: To evaluate the clinical and radiological findings in diagnosing spontaneous malignant transformation of fibrous dysplasia. METHODS: Fifteen cases of sarcomatous transformation proved by operation and pathological examinations were found in a group of 356 patients with fibrous dysplasia, and their radiological manifestations were retrospectively studied. The 15 cases included 8 osteosarcomas, 5 fibrosarcomas 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 monostotic type. RESULTS: Malignant transformation most frequently occurs in the cystic expansive lesion of the long tubular bone. Pains, swelling and late appearance of a bony mass are the main clinical manifestations. The early radiological features of sarcomatous transformation in fibrous 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 osteosarcomatous transformation, while ring-like and spottycalcification in the tumor matrix is indicative of chondrosarcoma. Fibrosarcoma usually shows simple osteolytic destruction. CONCLUSIONS: According to the clinical radiological findings, patients of sarcomatous transformation can be detected in the early stage. These radiological findings may be used as a clue for differentiating various kinds of sarcomatous transformation.