DNA tetraploidy in Feulgen-stained bladder washings assessed by image cytometry

The prognostic utility of DNA cytometry has been demonstrated for irrigation specimens from bladder neoplasms. While the traditional method of measuring the DNA content of cells recovered by bladder irrigation is flow cytometry, image analysis has been applied increasingly, with successful results. In some cases, image analysis has been shown to detect DNA aneuploid populations missed by flow cytometry. The DNA aneuploid population most frequently missed by flow cytometry is in the DNA tetraploid range. The purpose of the present study was to review image cytometry data on bladder washings analyzed at the University of Florida Diagnostic Referral Laboratories during a one-year period, with special emphasis on the subset with DNA tetraploid histograms. Of the 205 cases reviewed, 127 (62%) were DNA diploid, 36 (18%) DNA aneuploid and 42 (20%) DNA tetraploid. Corresponding cytology was negative in 113/127 (89%) of DNA diploid, 3/36 (8%) of DNA aneuploid and 29/42 (69%) of DNA tetraploid cases. Within the DNA tetraploid group, 45% of cases had no clinical (cystoscopic) or pathologic (cytologic and histologic) evidence of neoplasia. None of these patients developed tumors during follow-up. The presence of DNA tetraploidy in cytologically negative cases should be interpreted cautiously.