Ploidy analysis in paraffin-embedded malignant fibrous histiocytoma by DNA cytofluorometry and fluorescence in situ hybridization

To prove the relationship between chromosomal aberration and DNA ploidy in human malignant fibrous histiocytoma (MFH), fluorescence in situ hybridization (FISH) and DNA cytofluorometry were performed in this study. For FISH study, the nucleus of each tumor cell was isolated from paraffin-embedded tissue of nine MFHs. Five chromosome-specific DNA probes (1p36, 1q12, 8q21.3, 11 centromere, and 17 centromere) were hybridized on cell nuclei. Cells with more than three probe signals were regarded as chromosome polysomy. All of the tumors analyzed by FISH had extra copies The average percentage of polysomy in all tumors was high, ranging from 10.2% to 49.2%. The DNA ploidy patterns, and the percentage of hyperdiploid cells showing a greater DNA content than diploid cells, were obtained from DNA cytofluorometry. Three of nine were diploid patterns and six were non-diploid patterns, and the percentage of hyperdiploid cells in all tumors was high, ranging from 9.1% to 61.9%. The percentage of polysomy could be correlated with the percentage of hyperdiploid cells in each cell. In this study, we found that the DNA ploidy change was closely correlated with aberrations of chromosome copy number in MFH. In addition, the alterations of specific chromosome copy number could be detected in MFH showing diploid cells. Thus, these data indicate that FISH and DNA cytofluorometry are available as a cytogenetic tool for the analysis of interphase nuclei of bone and soft tissue tumors including MFH.