Purpose of the study: Several studies have demonstrated better prognosis of chondrosarcomas arising in hereditary multiple exostosis or Ollier's disease. The aim of this study was to evaluate their clinical, radiological and histological features and compare their prognosis with other chondrosarcomas.
Material and methods: We reviewed twenty nine secondary chondrosarcomas among seventeen patients with osteochondroma (group A), and eight with Ollier's disease (group B). These tumors represented 12 p. 100 of all chondrosarcomas treated between 1950 and 1994 in Cochin Hospital. Two group B patients successively developed three multicentric chondrosarcomas. Twenty six resections (eight intra and eighteen extra-lesional), two disarticulations and one amputation were performed as primary treatment. The average follow-up of the study was 10.5 years. The results were evaluated by means of survival curves. The significance of the difference between the curves was determined by the log-rank test.
Results: The mean age of malignant change was 36 years old. The most frequent tumoral site was the innominate bone for group A and the femur for group B. In three cases, radiographs showed no malignant features. All chondrosarcomas were classified as grade 1 or 2. The ten-year survival rate was 82 p. 100 with no significant difference between the two groups. The survival rates were significantly different after carcinologic surgery (extra-lesional resection or amputation) and contaminated surgery (intralesional resection), with 5 and 88 p. 100 of local recurrences respectively.
Discussion and conclusion: These secondary chondrosarcomas represent about 10 p. 100 of all chondrosarcomas. They appear 15 years earlier. According to O'Neal and Ackerman classification, most of the tumors are well-differentiated (60 p. 100 grade I, 39 p. 100 grade II and 1 p. 100 grade III). Carcinologic surgery is generally curative. Ten-year survival rate is 94 p. 100. With equivalent grade and surgery, their prognosis is better as compared to primary chondrosarcomas.