P53 EXPRESSION AND DNA-PLOIDY OF CARTILAGE LESIONS

The aim of this study was to investigate the expression of a tumor sup pressor gene (p53) in cartilage lesions of bone and its relationship t o their histological grade and DNA ploidy. An immunohistochemical assa y for p53 and Feulgen-stained DNA preparations was subjected to comput erized image analysis. Enchondromas, vial chondromatosis, and low grad e (grade I and II) chondrosarcomas were diploid. High grade (grade III ) chondrosarcomas and high grade sarcomatous components of dedifferent iated chondrosarcomas were aneuploid. Well differentiated cartilaginou s components of dedifferentiated chondrosarcomas were diploid. Microsc opic examination showed weak focal positivity for p53 in one of 10 enc hondromas one of six examples of synovial chondromatosis, and three of four low grade (grade I and II) chondrosarcomas. All three high grade (grade III) chondrosarcomas were strongly positive for p53. The high grade sarcomatous component of all four dedifferentiated chondrosarcom as was strongly positive for p53, whereas only focal weak positivity w as noted in the well differentiated cartilaginous areas. These results were confirmed by quantitative computer-assisted image analysis, whic h showed that high grade aneuploid cartilage tumors demonstrated strik ingly higher levels of p53 than did diploid low grade malignant tumors or benign cartilage lesions. Copyright (C) 1995 by W.B. Saunders Comp any