The patient is 25 year old, female. From childfood she had hereditary multiple exostosis. 3 years ago the right thigh started to enlarge gradually and recently she has pain in the same region. From the clinical and X-ray points of view, the diagnosis was made as secondary chondrosarcoma in the upper part of the femur arising in cartilagenous exostosis. The mass was completly removed en-bloc and metal prosthesis was inserted. The tumor weighed 1250g. The histological diagnosis was osteochondroma. 8 months after the operation, there is no evidence of reccurence or metastasis.
