2001 CTOS Annual Meeting Posters— Biology

IS CYTOGENETIC ANALYSIS CLINICALLY USEFUL? AN ANALYSIS OF 101 CONSECUTIVE CASES OF BENIGN AND MALIGNANT BONE AND SOFT TISSUE TUMORS OF THE EXTREMITIES
Robert M Henshaw¹,  Barry M Shmookler²,  Martin M Malawer^1
1Department of Orthopedic Oncology Washington Cancer Institute Washington Hospital Center,  ²Department of Pathology Suburban Hospital

METHODS: 101 (51 malignant/50 benign) consecutive musculoskeletal tumors surgically excised at our institution underwent both cytogenetic analysis and traditional histologic evaluation. The successful culture rate for the cytogenetic analysis was 86%. 57% (26/46) of clearly malignant tumors successfully cultured demonstrated significant clonal abnormalities. 46% (19/41) of benign tumors cultured had significant cytogenetic clonal aberrations, including 8 lipomas, 4 PVNS, 3 GCT, 2 fibromatosis, 1 chondroblastoma and 1 schwannoma.

RESULTS: Specific cytogenetic aberrations seen in various benign tumors included chromosomal deletions, trisomies, translocations, inversions, ring and marker formations, as well as dicentric and telomeric associations. Increased cellular ploidy (more than 50 chromosomes per cell) was demonstrated in 16/46 malignant and 1/41 benign tumors. Hyperploidy was highly correlated with malignancy (p<0.0004, chi squared analysis): the only “benign” tumor was a multiply recurrent GCT demonstrating histologic changes consistent with early sarcomatous transformation. As expected, cytogenetic abnormalities frequently occurred in malignant tumors. Surprisingly, almost half of the benign tumors tested had significant clonal cytogenetic aberrations. Consistent findings of extra chromosomes 5 and 7 in samples of PVNS strongly favor a neoplastic origin for this condition.

CONCLUSION: Although the presence or absence of cytogenetic aberrations cannot be used as a determinant of malignant potential, increased cellular ploidy is highly indicative of malignancy. Cytogenetic analysis can be useful in classifying the malignant potential of recurrent and difficult to diagnose tumors of the musculoskeletal system.