P53 MUTATIONS IN CHONDROSARCOMA

Chondrosarcoma is a primary bone tumor that has several different grad es and variants. We evaluated 48 chondrosarcomas for p53 overexpressio n and p53 mutations. p53 expression was evaluated with immunohistochem istry using monoclonal antibodies PAb421, PAb1801, and PAb240. p53 mut ations were identified with single-strand conformational polymorphism (SSCP) and DNA sequencing in selected cases. Immunohistochemistry reve aled nuclear staining with PAb421 and PAb 1801 in the spindle cell por tion of one dedifferentiated chondrosarcoma. SSCP analysis was abnorma l only in the case with positive immunostaining and localized the muta tion to exons 7 and 8. DNA sequence analysis identified a point mutati on of G to C in codon 276, resulting in an amino acid substitution of proline for alanine. This point mutation has been reported previously in other tumors but not in chondrosarcoma. Assimilation of our results with previous studies suggests that p53 mutations are present in a mi nority of chondrosarcomas but when present, are in higher grade chondr osarcomas and their variants.