Cytologic Assessment of the Supernatants of Formalin Solution Following Histologic Examination of Transurethral Biopsy/Resection Specimens.

Context.—: Urothelial denudation seen in transurethral biopsy specimens may occasionally indicate the presence of discohesive high-grade urothelial carcinoma (HGUC).

Objective.—: To determine if denuded urothelial cells can be detected in the supernatants of formalin solution collected from the containers of transurethral biopsy/resection specimens after the entire tissue was submitted for histologic examination.

Design.—: We assessed the formalin supernatants by processing for cell block (n = 43) or ThinPrep smear (n = 57).

Results.—: In the cell block cohort, only 2 of 43 cases (5%) (1 pTa HGUC, 1 pT1 HGUC) showed rare urothelial cells. By contrast, in the ThinPrep method, the smear was satisfactory for evaluation in 52 of 57 cases (91%). The cytologic diagnosis of HGUC was made in the smears from 7 of 12 (58%) pTa/pT1 cases and 6 of 9 (67%) pTis cases. Remarkably, HGUC cells were detected in 2 of 5 cases (40%) with histologic diagnosis of urothelial atypia suspicious for but not diagnostic of urothelial carcinoma in situ. Additionally, in 31 cases exhibiting urothelial denudation without definitive cancer on hematoxylin-eosin-stained slides, HGUC cells (2 of 31; 6%), atypical urothelial cells (5 of 31; 16%), or benign-appearing urothelial cells (20 of 31; 65%) were present, and only 4 of 31 (13%) were unsatisfactory.

Conclusions.—: Cytologic examination of ThinPrep smears from the formalin supernatants even following submission of the entire transurethral biopsy/resection specimens for histologic examination is useful for assessing denuded urothelial cells. This technique can particularly be applied to nonneoplastic cases showing extensive urothelial denudation to detect possible malignant cells and/or indeterminate cases to assist to make a more definitive diagnosis.