DNA ploidy in seminal vesicle cells - A potential diagnostic pitfall in urine cytology

OBJECTIVE: To verify that abnormal DNA ploidy in urine cytology can occasio nally be attributed to contamination by seminal vesicle cells. STUDY DESIGN: In the first part of this study, we analyzed the DNA content of six urine cytology specimens containing seminal vesicle cells. In the se cond part, we evaluated 21 Feulgen-stained prostate core biopsies containin g seminal vesicle-type epithelium using a CAS-200 system. DNA index, prolif erative activity (S+G(2)M) and degree of hyperploidy (>5C) were determined in each case. RESULTS: All six urine cytology specimens were diploid, with all but one co ntaining hyperploid cells (range, 0-16%; mean, 6.3%). Seminal vesicle cells from prostate biopsies showed a broad range of ploidy abnormalities. Ten c ases (48%) showed an aneuploid peak, two cases (9%) showed a tetraploid pea k, and nine cases (43%) showed only a diploid peak. All but one case showed both an elevation in proliferative activity (mean S+G(2)M, 24.2%) and some hyperploid cells (mean, >5C; 4.5%). CONCLUSION: Seminal vesicle cells, although rarely seen in urine cytology, can cause abnormal DNA ploidy measurements. Morphologic criteria remain vit al to an accurate cytologic diagnosis.