Introduction: The most common histologic type of bladder cancers is urothelial carcinoma, accounting for 90% and 95% of bladder cancers. Urinary bladder carcinomas may sometimes have diverse histologic features, which differ from the conventional urothelial carcinoma of the bladder. These divergent tumors are divided into four major categories as: variant forms of urothelial carcinoma, squamous cell carcinoma, adenocarcinoma, and undifferentiated carcinoma. In the first category, the most common divergent tumor group is the carcinomas with squamous and/or glandular differentiation. Squamous differentiation occurs in up to 10-20% of urothelial carcinomas of the bladder and glandular differentiation is less common than squamous differentiation. The clinical significance of squamous and glandular differentiation remains uncertain. In this study, we evaluated the effects of focal and widespread squamous and/or glandular differentiation on stage, grade and survival of bladder tumor patients at presentation. Materials and Methods: Between February 1998 and December 2005, 236 patients with urothelial carcinoma, who had been treated with transurethral resection were evaluated retrospectively. Patients were divided into two groups as; Group1: tumor patients with focal squamous and/or glandular differentiation, Group 2: patients with widespread squamous and/or glandular differentiation. All patients were evaluated with physical examination, routine hematologic and biochemical analysis, urinary ultrasonography (USG) or intravenous urography (IVU), cystoscopy, and also with computerized tomography (CT) if indicated. Clinical and histological staging were done according to TNM classification (2002). The data about stage and grade distribution and the effect of squamous and glandular differentiation on survival rates were evaluated. Results: The mean age and the mean follow-up of the patients were 65.46 +/- 10.4 (range 36-81) years and 45.17 +/- 13.8 (6-71) months, respectively. Within the total 236 transurethrally resected bladder tumors 37 (15.7%) of them were tumors with squamous and/or glandular differentiation. Among these patients 25 (group 1) had focal squamous differentiation and 12 (group 2) had widespread squamous differentiation. Superficial and invasive tumor rates were found as 72% (n=18) and 28% (n=7) in Group 1 and 8.3% (n=1) and 91.7% (n=11) in Group 2 (p<0.05). Among all patients a total of 34 (91.9%) patients had high grade urothelial bladder tumors. The mean survival rates were found as 76% (n=19) in Group 1 and 33.3% (n=4) in Group 2. Tumor size and tumor grade were not statistically different between group 1 and group 2 (p>0.05). In multivariate analysis squamous and/or glandular differentiation was not a independent prognostic factor on survival (p>0.05). Moreover, multivariate analyses have shown that mortality rate of tumors with widespread squamous differentiation is seven times greater than that of tumors with focal squamous differentiation. Conclusion: There was a significant difference between bladder tumors with focal and widespread squamous and/or glandular differentiation with regard to clinical stage and tumor grade. Although squamous and glandular differentiation are not accepted as independent prognostic variables based on the results of multivariate analyses, mortality rate of tumors with widespread squamous differentiation is seven times greater than that of tumors with focal squamous differentiation
