Impact of histological variants on the outcomes of nonmuscle invasive bladder cancer after transurethral resection

Purpose of review The scoring system used after transurethral resection of the bladder (TURB) to guide clinical decision-making regarding nonmuscle invasive bladder cancer (NMIBC) largely assumes that NMIBCs are pure urothelial carcinomas and does not take into account the role of variant histology. This review outlines pathological and clinical characteristics of major histological variants to determine their potential impact in therapeutic strategies for the management of NMIBC. Recent findings Assessing the presence of histological variants in NMIBCs after TURB currently remains challenging because of limited tissue sample sizes. However, the presence of these variants often indicates poor prognosis with increased risk for recurrence and progression. Among them, only the following histological variants are indications for Bacillus Calmette-Guerin intravesical instillations: squamous or glandular differentiations and deceptively benign or lymphoepithelioma-like carcinomas. However, patients diagnosed with any other variants should be promptly considered for early radical cystectomy, and only those with small cell carcinoma might benefit from neoadjuvant chemotherapy with a neuroendocrine-specific regimen. Summary Based on the available literature (e.g., small case studies and retrospective studies), the existence of histological variants after TURB appears to massively impact NMIBC outcomes.