Application of laser scanning cytometry for evaluation of DNA ploidy in routine cytologic specimens

The laser scanning cytometer (LSC) is a relatively new instrument that combines the features of both flow and static image cytometry. The purpose of this study was to examine the application of the LSC for evaluation of DNA ploidy in routine cytologic specimens. The material for this study consisted of 60 routine cytologic specimens obtained from 33 males and 27 females ranging in age from 23-87 yr (mean, 58 yr). The specimens were simultaneously stained with propidium iodide and FITC-cytokeratin, either on Thin-Prep slide (35 cases) or in a concentrated cell suspension (25 cases). In each case a minimum of 500 cells was evaluated (range, 527-17,963; mean, 3,889). All abnormal cell populations were relocated for the presence of malignant cells. The results were defined as diploid and aneuploid/tetraploid. In 10 bladder washes, the results of LSC were compared to results of flow cytometry. Out of 60 specimens, 7 (11%: 6 bladder washes and 1 renal wash) were excluded due to low cellularity. Of the remaining 53 cases, 11 (20%) were aneuploid/tetraploid, and 42 (80%) were diploid. All but one cytologically diagnosed malignancy had abnormal DNA content. Additionally, two bladder washes diagnosed as suspicious and atypical were aneuploid. All abnormal LSC results were confirmed by relocation of the cells. The concordance between flow cytometry and LSC in the 10 control bladder washes was 100%. In conclusion, LSC proved to be a suitable instrument for the evaluation of DNA ploidy in routine cytologic specimens.