Immunoexpression of p53 & CK 20 in Infiltrating Urothelial Carcinoma of Urinary Bladder and their Association with Histopathological Grading and Muscle Invasiveness

Abstract

Background: Urothelial carcinoma is the most frequent malignancy of the urinary bladder, and histological grading of resected specimens remains subject to poor interobserver reproducibility. Objective: This study examined p53 and cytokeratin 20 (CK20) immunoexpression in urothelial carcinoma and their correlation with histopathological grade and muscle invasion. Methods: This cross-sectional observational study analyzed 50 histologically confirmed urothelial carcinoma specimens (38 transurethral resection of bladder tumor [TURBT] samples and 12 archival blocks) collected at the Department of Pathology, Rajshahi Medical College, from March 2022 to February 2024; p53 and CK20 expression were assessed immunohistochemically and graded as negative, weak, or strong positive, with statistical analysis performed in SPSS v26.0. Results: The mean age of the 50 participants (40 male, 10 female) was 56.84 ± 10.93 years. High-grade tumors comprised 31 (62.0%) cases and muscle-invasive tumors 17 (34.0%). p53 was strongly positive in 30 (60.0%) and weakly positive in 6 (12.0%) cases, with strong positivity concentrated in high-grade (83.3%) and muscle-invasive (94.1%) tumors (p = 0.0003 and p = 0.002, respectively). CK20 was diffusely positive in 23 (46.0%) and focally positive in 7 (14.0%) cases, again predominating in high-grade (87.0%) and invasive (76.5%) tumors (p = 0.002 and p = 0.005). Combined p53/CK20 positivity occurred in 25 (50.0%) cases and was concentrated in high-grade tumors (84.0%; p = 0.0001), though its association with muscle invasion did not reach significance (p = 0.063). Conclusion: p53 and CK20 immunoexpression correlate strongly with histopathological grade and, individually, with muscle invasiveness, supporting their adjunctive use in risk stratification.