Histological Subtypes of Bladder Cancer: Epidemiology, Molecular Biology, and Clinical Implications.

Histological subtypes of bladder cancer are generally associated with more aggressive disease, higher stage at presentation, and worse prognosis compared to conventional urothelial carcinoma. Recent updates in classification systems have further refined the distinction between true histologic subtypes and divergent differentiation, underscoring the complexity of these tumors. Emerging molecular profiling studies have identified subtype-specific genomic alterations, including ERBB2 amplification in micropapillary subtype carcinoma, CDH1 loss in plasmacytoid subtype carcinoma, and TP53 and RB1 co-alterations in neuroendocrine bladder cancer, which may contribute to differences in tumor biology and therapeutic response. Despite these advances, the histological subtypes of bladder cancer remain underrepresented in prospective clinical trials, leading to significant gaps in evidence-based management. Treatment responses vary widely across subtypes, with some demonstrating sensitivity to platinum-based chemotherapy or immunotherapy, while others appear less responsive to conventional approaches. This review summarizes the current understanding of the epidemiology, molecular landscape, and clinical behavior of major bladder cancer subtypes and highlights emerging opportunities for personalized treatment strategies, biomarker-driven therapies, and more inclusive clinical trial design to improve outcomes in this high-risk population.