Significance of tissue fragments in voided urine specimens

OBJECTIVE: To determine the diagnostic significance of tissue fragments in voided urine specimens. STUDY DESIGN: We reviewed all the voided urine specimens collected and processed by the Millipore filter technique (Bedford, Massachusetts, U.S.A.) at our institution between January 1, 1997, and December 31, 1998, and the corresponding biopsies obtained within 120 days after urine examination. The type and number of tissue fragments were correlated with the histologic diagnosis and clinical features; the results were compared to those from a recently published study. RESULTS: Of the 2,553 voided urine specimens examined, 174 (7%) had corresponding biopsies. Cell groups (tissue fragments) consisting of either flat sheets or three-dimensional structures were significantly more common (57%) (chi 2 P < .005) in urine specimens with biopsies revealing urothelial malignancies than in negative biopsies (6%). Three-dimensional groups were also statistically more common in cases with invasive transitional cell carcinoma. Proper identification of tissue fragments was highly significant and correlated with urothelial neoplastic changes. CONCLUSION: The results of the present investigation using the Millipore filter technique for voided urine cytology processing, differed from those of a recently published study that employed cytocentrifugation. Tissue fragments, to be differentiated from groups, clumps or clusters that often result from centrifugation and other concentration artifacts, were strongly associated with urothelial neoplasia, uncommonly with nonneoplastic disease processes affecting the urinary tract but always with urothelial disease.