ABSTRACT

We summarize the results and clinical usefulness of cytogenetic analysis that is routinely performed for musculoskeletal tumors. We performed cytogenetic analysis and traditional histologic evaluation on 101 (51 malignant/ 50 benign) consecutive tumors that were surgically excised. The successful culture rate for cytogenetic analysis was 86% (87/101). Fifty-four percent (25/46) of clearly malignant tumors that were successfully cultured demonstrated significant clonal abnormalities. Fifty-one percent (21/41) of benign tumors that were cultured had significant cytogenetic clonal aberrations. Increased cellular ploidy (> 50 chromosomes/cell) was demonstrated in 14/46 malignant and 1/41 benign tumors that were successfully cultured. Hyperploidy was highly correlated with malignancy (p < 0.001); the only "benign" tumor was a multiply recurrent and giant cell, demonstrating histologic changes consistent with early sarcomatous transformation. As expected, cytogenetic abnormalities frequently occurred in malignant tumors. Surprisingly, almost half of the benign tumors had significant clonal cytogenetic aberrations. Consistent findings of extra chromosomes 5 and 7 in samples of pigmented villonodular synovitis strongly favored a neoplastic origin for this condition. Although the presence or absence of cytogenetic aberrations cannot be used to determine malignant potential, increased cellular ploidy is highly indicative of malignancy. Modern molecular genetics have become more popular, but cytogenetic analysis can be useful for classifying the malignant potential of recurrent and difficult to diagnose tumors of the musculoskeletal system.