Squamous cell carcinoma (SCC) of the urinary bladder is a malignant epithelial tumor exhibiting pure squamous differentiation without a conventional urothelial carcinoma component. It should be distinguished from urothelial carcinoma with squamous differentiation (UCSD), in which squamous differentiation occurs within an otherwise urothelial carcinoma. This distinction is clinically important because histologic subtype influences treatment planning and interpretation of prognosis. ^{[1] [2]}

Bladder SCC is uncommon in most Western populations but represents a substantially larger proportion of bladder malignancies in regions historically affected by urinary schistosomiasis. Its epidemiology varies geographically and reflects differences in environmental exposures and patterns of chronic bladder irritation. ^[3][4]

Compared with urothelial carcinoma, bladder SCC has a more balanced sex distribution, with reported male-to-female ratios of approximately 0.9–1.6:1, compared with approximately 3:1 for urothelial carcinoma. Registry studies also report a higher proportion of female and Black patients among those diagnosed with SCC. These demographic differences are population-level associations and should not be interpreted as individual-level determinants of disease. ^[5][6][7]

Bladder SCC is strongly associated with chronic bladder inflammation and irritation. Important clinical contexts include urogenital infection with *Schistosoma haematobium*, prolonged indwelling urinary catheterization, neurogenic bladder, recurrent urinary tract infection, and bladder calculi. Tobacco use also contributes to bladder cancer risk, although the association between tobacco and pure SCC is less consistent than that established for urothelial carcinoma. The underlying oxidative-stress and chronic-inflammation mechanisms are addressed in the Pathophysiology microchapter. ^[8][9][10]

Patients with bladder SCC frequently present with hematuria and other symptoms related to bladder involvement. Chronic urinary symptoms may also occur in patients with longstanding inflammatory or irritative conditions. Many patients have muscle-invasive disease at diagnosis, and locally advanced tumors are common. ^[11][12][13]

The characteristic clinical pattern is marked local aggressiveness and a high burden of locally advanced disease. However, the extent of regional or distant spread varies by stage and population; SCC should not be assumed to have a uniformly low metastatic potential. ^[14][15]Mercier J, Cornillon P, Barthélémy P, et al. Squamous cell carcinoma of the bladder: current evidence, therapeutic challenges, and research perspectives from the French AVENTUR Group. *Crit Rev Oncol Hematol*. 2026;225:105505. doi:10.1016/j.critrevonc.2026.105505.^[16]

Its presentation, demographic distribution, and outcomes vary between schistosomal and non-schistosomal populations.

Pure SCC demonstrates malignant squamous differentiation without a conventional urothelial carcinoma component. UCSD contains both urothelial carcinoma and a squamous component. Accurate histopathologic classification is essential because the two entities are not managed identically. ^[17][18]

Unlike urothelial carcinomas, for which the WHO/ISUP low-grade and high-grade framework is commonly used, SCC is generally described by conventional differentiation categories: well differentiated, moderately differentiated, or poorly differentiated. Histologic grade should be interpreted alongside tumor stage, nodal status, lymphovascular invasion, and surgical margin status. ^[19][20]

Prognosis is strongly influenced by tumor stage, regional lymph node involvement, resectability, surgical margins, and treatment. Registry studies have reported worse survival for SCC than for urothelial carcinoma in several populations. In a National Cancer Database analysis of muscle-invasive bladder cancer, SCC was independently associated with poorer survival (adjusted hazard ratio [HR] approximately 1.79). In a California Cancer Registry analysis, SCC was associated with worse disease-specific survival (HR approximately 2.61). These estimates arise from different cohorts and endpoints and should not be interpreted as directly interchangeable. ^[21][22]

The stage-adjusted survival disadvantage is not uniform across all clinical settings. In a SEER analysis, SCC was associated with increased mortality among patients with stage I–II disease who did not undergo upfront cystectomy and among those with stage III–IV disease. However, SCC was not associated with increased mortality among patients with organ-confined stage I–II tumors treated with upfront cystectomy. This suggests that the prognostic effect of squamous histology depends in part on disease extent and treatment context. ^[23]

The independent prognostic significance of squamous differentiation in UCSD remains unsettled. A 2026 propensity score-matched analysis reported worse overall survival for UCSD than for pure urothelial carcinoma (HR 1.52), with survival outcomes not significantly different between UCSD and pure SCC. A 2020 meta-analysis also found that squamous differentiation was associated with poorer disease-free survival. Conversely, an Ontario population-based study found no significant adjusted survival disadvantage for UCSD compared with pure urothelial carcinoma and described a more rapid early disease course for SCC, with survival converging by five years. These differences likely reflect variation in populations, endpoints, case definitions, and adjustment methods; the available evidence does not establish a single universal prognostic effect. ^[24][25]

Management depends on whether the tumor is pure SCC or UCSD, as well as clinical stage, resectability, patient fitness, and treatment goals. For localized or resectable pure SCC, definitive local treatment is central, with surgery or selected multimodal approaches considered by a multidisciplinary team. Evidence supporting perioperative systemic chemotherapy in pure SCC remains limited, and a proven role for neoadjuvant or adjuvant chemotherapy has not been established. ^[26]

For advanced or metastatic pure SCC, enrollment in a clinical trial is preferred when available. For selected patients, combination chemotherapy such as cisplatin, ifosfamide, and paclitaxel may be considered. Postoperative radiotherapy may be an option in selected circumstances, including positive surgical margins. Detailed treatment selection and regimen-specific evidence are addressed in the Medical therapy microchapter.^[27]

UCSD should not automatically be managed according to the pure-SCC pathway. Because UCSD retains a urothelial carcinoma component, NCCN advises treatment in a manner similar to pure urothelial carcinoma, while recognizing its potential for a more aggressive natural history. Management should be individualized according to stage, histology, patient factors, and multidisciplinary assessment. ^[28]

– Distinguish pure bladder SCC from urothelial carcinoma with squamous differentiation because the distinction affects treatment planning. – Consider chronic bladder irritation, urinary schistosomiasis, prolonged catheterization, neurogenic bladder, recurrent urinary infection, and bladder calculi when assessing relevant risk factors. – Expect a near-equal sex ratio and a higher proportion of female and Black patients than in urothelial carcinoma cohorts. – Recognize the frequent presentation with muscle-invasive or locally advanced disease and the importance of local control. – Interpret stage-adjusted survival estimates in the context of disease extent and treatment; the survival disadvantage is not uniform across all stages and treatment settings. – Recognize that the independent prognostic effect of squamous differentiation in UCSD remains controversial. – Refer advanced pure SCC for clinical-trial consideration when feasible, and individualize treatment through multidisciplinary review.