Bladder Cancer Variant Histologies: Epidemiology, Diagnosis, Treatment and Prognosis

Bladder cancer (BC) is an increasingly frequent cancer worldwide, being currently the sixth most frequent tumor and the thirteenth leading cause of cancer death. Among all BC cases, pathologists have identified several histomorphologies different from the conventional urothelial carcinoma. Although rare, these histologic variants have a distinct growth pattern, an altered cell differentiation and an unusual clinical behavior, especially concerning clinical presentation at diagnosis, response to the standard treatment and prognosis. Therefore, an updated review of this topic should be useful to aid clinicians in a better evidence-based decision-making. This chapter aims to summarize the current literature on the most common histologic variants regarding their epidemiology, clinical presentation at diagnosis, treatment options and prognosis. This includes both non-muscle invasive BC and muscle invasive BC as well as metastatic disease. A special focus will be placed on the role of neoadjuvant chemotherapy and early cystectomy and its prognostic implications.