Abstract
Objective: We studied the frequency with which (1) urothelial carcinomas were concomitant with flat lesions composed of grade 1 urothelial carcinoma cells (G1 flat lesions), (2) cells derived from G1 flat lesions were recognized in urinary cytological smears and their cytological features, and (3) histological features of G1 flat lesions reacting positively to Cytokeratin 20 (CK-20).
Study Design: We observed (1) histological preparations of 47 urothelial carcinomas of the urinary bladder, and (2) urinary cytological smears from voided urine in 18 cases of G1 flat lesions and CK-20 immunohistochemical stainning preparations of G1 flat lesions and urothelial carcinomas.
Results: G1 flat lesions were recognized in 57% of urothelial carcinomas. Cells from G1 flat lesions were small in nuclear size and few in number in urinary cytological smears and appeared in 61% of those from urothelial carcinomas with G1 flat lesions. Some 56% of G1 flat lesions reacted positive by to CK-20.
Conclusions: Cells derived from G1 flat lesions may appear in cytological smears even after main papillary tumors have been resected. G1 flat lesions are thought to correspond to urothelial dysplasia in the WHO classification of tumors of the urinary system.
