Laser scanning cytometry for the detection of neoplasia in urologic cytology specimens

BACKGROUND: The objective of the current pilot project was to assess the efficacy of laser scanning cytometry (LSC) for DNA ploidy analysis of atypical urologic cytology specimens to enhance the distinction between benign and malignant changes. METHODS: Forty selected urologic cytology specimens that previously had been categorized as normal, atypical, or malignant were studied. Nuclear propidium iodide and fluorescence intensity measurements were converted to pixel values, which were used to create scattergrams that excluded debris and cell clusters from ploidy analysis, creating a gated (isolated) region of predominantly single cells for LSC ploidy analysis. Integral histograms then were created to show the number of cells present in diploid, tetraploid, and aneuploid peaks; these histograms also were used to assess DNA ploidy. RESULTS: Ten normal specimens, 10 malignant specimens, and 20 atypical specimens were examined to assess the efficacy of LSC ploidy analysis. Normal and malignant specimens generated reference histograms for comparison with the atypical specimens and exhibited 90% specificity and 100% sensitivity. Ten atypical aneuploid specimens had histogram and scattergram patterns similar to those produced by malignant specimens and, using the cytometer's relocation feature, the presence of atypical cells was confirmed in the aneuploid regions. CONCLUSIONS: The authors determined that DNA ploidy analysis of atypical urologic cytology specimens using LSC is a useful adjunct tool for identifying malignant specimens that lack sufficient cytologic criteria for diagnosis by light microscopy alone. However, LSC is time consuming and requires expensive equipment.