Immunohistochemical Study of the Role of CK20, p53 and Ki-67 in Differentiation of Some Urothelial Lesions and Urothelial Carcinoma of the Urinary Bladder

Abstract
Background: Bladder cancer is the most common malig-nancy affecting the urinary tract. Distinguishing between urothelial dysplasia and carcinoma in situ based on histopatho-logical features alone is often difficult.
Aim of Work: The aim of the current work is to distinguish between urothelial hyperplasia, urothelial dysplasia from urothelial carcinoma by using CK20, p53 and Ki-67 immu-nomarkers, determine the pattern and extent of their immuno-reactivity and correlate immuno-histochemical results with the clinicopathological parameters.
Material and Methods: Fifty cases of urothelial carcinoma (38 cases) and some flat urothelial lesions (12 cases) were collected retrospectively. Tissue specimens were in the form of radical cystectomy (nine specimens) and transurethral resection of the tumor (TURT) (forty one specimens). They were stained by H&E, CK20, p53 and Ki-67 for immunohis-tochemical study. The relationship between their expression and the available clinicopathological features were evaluated.
Results: CK20, p53 and Ki-67 expressions can signifi-cantly differentiate urothelial hyperplasia from urothelial dysplasia as the whole panel is negative in urothelial hyper-plasia and positive with scattered expression in urothelial dysplasia. Also pattern of expression of CK20, p53 and Ki-67 expression are suggesting for the diagnosis of either urothelial dysplasia or urothelial carcinoma in situ as their expressions show diffuse positivity throughout the urothelium in urothelial carcinoma in situ. These markers were statistically significant in grading of urothelial carcinoma as higher tumor grade associated with decreased CK20 expression and in-creased p53 and Ki-67 expression. CK20 expression was statistically significant in tumor stage as higher tumor stage was associated with decreased CK20 expression.
Conclusions: Abnormal CK20 expression in urothelial cells plus overexpression of p53 and Ki-67 are indicators of dysplastic change in urothelial mucosa. A panel of CK20, p53 and Ki-67 can be a useful tool to confirm the diagnosis of CIS and can be helpful to distinguish it from dysplastic changes. Combined use of these markers may be helpful in assigning grade of urothelial carcinoma especially when histologic features are borderline.