[Clinical evaluation of multiple exostoses (17 cases) on bone scintigraphy].

17 patients with multiple exostoses were examined on bone scintigraphy. Inheritance was recognized on seven patients (41%). Onset age of 15 patients was under 20 years old and 10 patients were under 10. The number of lesions was 211 and they were usually recognized at metaphyses of long bones. The degree of accumulation was classified into four grades; 0 (not increased), 1 (slightly-mild), 2 (moderate) and 3 (strong). 153 lesions (73%) did not show definite increased activity (Grade 0, 1). Grade 3 included 14 lesions and they tended to be strongly calcified on X-P. This disease was said to transform into chondrosarcoma in 10 to 20%. Transformation was said to occur preferably in adults at heavily calcified lesion or one which showed irregularly thick hyaline cartilage. Such lesions showed more increased accumulation than normal bones. In our cases three cases were resected for this reason but turned out to be benign histologically. One case showed malignant transformation. On this case a large malignant tumor replaced the parent bone and bone scan showed the cold lesion. Bone scintigraphy was considered to be useful to evaluate the biological activity of multiple exostoses.