Superficial urothelial (umbrella) cells - A potential cause of abnormal DNA ploidy results in urine specimens

OBJECTIVE: To determine the DNA ploidy distribution in urothelial superfici al (umbrella) cells and to assess the value of the image analysis operator' s experience. STUDY DESIGN: DNA ploidy teas assessed in 12 cytologically negative bladder washes stained with Feulgen stain. All 12 cases were evaluated independent ly by three operators with different levels of cytopathology experience and different goals. Operator I (experienced) selected only nuclei of urotheli al cells, avoiding nuclei of superficial cells; operator 2 (experienced) se lected only nuclei of superficial cells; operator 3 (inexperienced) selecte d the largest and most-atypical-looking nuclei. Each operator measured a to tal of 100 nuclei per case. RESULTS: Operator I found all cases to be diploid (97% of nuclei on average ). Operators 2 and 3 showed it wide range of results. Almost half the nucle i (47%) analyzed by operator 2 were in the diploid region, a third (35%) we re in the temploid region, and the remaining (18%) ones had it DNA index (D I) in the range of 1.2-1.8 or >2.5. Operator 3 obtained the most abnormal r esults. Only 9% of the nuclei were diploid, while 37% were in the tetraploi d region, 18% were in the hyperploid region, and 35% had a DI in the range of 1.2-1.8. Differences among results obtained by each operator were statis tically significant. CONCLUSION: The nuclei of superficial (umbrella) cells often have abnormal DNA content, which may cause abnormal DNA ploidy results in cytomorphologic ally normal bladder washes. Consequently, the nuclei of superficial cells s hould be avoided in the evaluation of urine samples. DNA analysis of urine specimens requires selection of nuclei only of deep urothelial cells by an experienced operator.