Cytologic evaluation of low grade transitional cell carcinoma and instrument artifact in bladder washings

OBJECTIVE: To identify key cytologic features for the separation of low grade transitional cell carcinomas (TCCs) from nonneoplastic lesions in bladder washings. STUDY DESIGN: The cytomorphologic features of 95 bladder washing specimens showing papillary fragments, which included 50 low grade TCCs and 45 nonneoplastic lesions, were reviewed retrospectively. RESULTS: Bladder washings from low grade TCCs showed papillary and irregular groups of cells with ragged borders, cytoplasmic homogeneity and subtle nuclear changes, such as increased nuclear/cytoplasmic ratio and irregular nuclear border. Bladder washings after instrumentation from nonneoplastic lesions of the bladder showed cellular specimens with cohesive, ball-shaped and papillary clusters with smooth borders lined with a denser-staining cytoplasmic collar. Reactive urothelial cells often displayed loose aggregates with irregular borders but no cytoplasmic collar. CONCLUSION: In bladder washing cytology, nuclear changes and cytoplasmic homogeneity play a major role in the diagnosis of carcinoma.