Tumor heterogeneity in DNA ploidy of renal cell carcinomas as revealed by static cytofluorometry and flow cytometry

Abstract

DNA ploidy of 49 renal cell carcinomas of 46 patients were examined with static cytofluorometry (SCM) and flow cytometry (FCM). We used several paraffin blocks for each tumor (mean, 2.4), separated each block into several samples based on histological findings, and measured the DNA content of each sample. More samples could be analyzed with SCM than with FCM. With FCM, it was sometimes difficult to detect polyploid cells, or to determine whether diploid cells were tumor cells or stromal cells. DNA heterogeneity might thus be more accurately detected with SCM than with FCM. DNA aneuploidy was demonstrated for 59% of the tumors, and was significantly less common in grade 1 tumors than in higher-grade tumors. The incidence of polyploid cells in diploid tumors tended to increase with grade of tumor. Fifty-five percent of the tumors displayed DNA heterogeneity, the incidence of which tended to increase with grade of tumor. Ninety-four percent of the tumors were found to yield a diploid cell line. The findings of this study indicate that DNA content is associated with the histological grading. Diploid tumors with polyploid cells should be dealt with clinically in a separate fashion from diploid tumors without them. These findings suggest that diploid renal cell carcinomas with polyploid cells may be an intermediate stage between diploidy and aneuploidy.