Flow cytometric and quantitative image cell analysis of DNA ploidy in renal chromophobe cell carcinoma

Flow cytometry and quantitative image cell analyses were performed on a series of 31 chromophobe cell carcinoma and the findings were compared with those from 14 clear cell carcinomas. Thirty of 31 chromophobe cell carcinomas had significant hypodiploid cell clones with both techniques. By contrast, none of the 14 clear cell carcinomas was hypodiploid. Using quantitative image cell analyses, four groups of nuclei with hypodiploid, diploid, hyperdiploid, and tetraploid/hypertetraploid DNA patterns were identified, and their relative proportions were compared. In most of the chromophobe cell carcinomas, the predominant nuclear pattern was hypodiploid, and in clear cell carcinoma, diploid nuclei were most frequent. The number of binucleated cells in chromophobe cell carcinomas varied from 1.40% to 23% (mean, 10.8%) whereas, in clear cell carcinoma, these varied from 0.4% to 9.2% (mean, 2.5%). Evaluation of DNA content of double hypodiploid nuclei in chromophobe cell carcinomas showed that their combined DNA content was essentially similar to that of single hyperdiploid nuclei, thus suggesting polyploidy resulting from the fusion of these nuclei. Polyploidy may indeed be the basis for nuclear heterogeneity in chromophobe cell carcinoma. Scatterplots generated by plotting nuclear DNA mass against nuclear area produced patterns that were distinctive for the two types of carcinoma. We believe that the comparative findings in this study provide a comprehensive understanding of the ploidy status of chromophobe carcinoma and that these findings may be used as supportive evidence for establishing the diagnosis of chromophobe cell carcinoma.