Chromosome 9 alterations and trisomy 22 in central chondrosarcoma: A cytogenetic and DNA flow cytometric analysis of chondrosarcoma subtypes

Chondrosarcomas are malignant cartilaginous tumors. Most are located in the medullar cavity (central chondrosarcoma), and a minority develop in a pree xisting osteochondroma (peripheral chondrosarcoma). The authors present kar yotypes for 37 central, peripheral, juxtacortical, and dedifferentiated cho ndrosarcomas. Using loss of heterozygosity (LOH) analysis and DNA flow cyto metry, the authors previously showed that central and peripheral chondrosar comas probably evolve by different genetic mechanisms. Peripheral chondrosa rcoma is characterized by genetic instability, as was previously shown by a high percentage of LOH and a broad range in DNA ploidy. The authors now sh ow that all peripheral chondrosarcomas tested are aneuploid. combined with many nonspecific chromosomal aberrations. Two juxtacortical chondrosarcomas showed normal chromosome numbers combined with limited structural alterati ons. substantiating that juxtacortical and peripheral chondrosarcomas are t wo clinicopathologically different entities with a different genetic backgr ound. Central chondrosarcomas were previously found to be peridiploid with limited LOH, most frequent at 9p21. In the current study, chromosome 9 was involved in five of seven central chondrosarcomas compared with only one of four peripheral chondrosarcomas. Three central tumors showed involvement o f the 9pl2-22 region, suggesting an important role for chromosome 9 in the oncogenesis of central chondrosarcoma. Moreover, trisomy 22 was found in fo ur central chondrosarcomas only.