Analysis of pathological character of 4 200 bladder tumor cases

Objective To investigate the histopathologic characteristics of bladder tumor and provide theoretical basis for the reasonable selection of treatment modality. Methods This retrospective study collected the pathological data of 4 200 bladder tumor from May 2001 to October 2014. There were 3 443 male and 757 female, and the average diameter of these tumors was (1.8±0.6) cm (ranged 0.2 to 6.5 cm). Among all cases, 3 214 (76.5%) cases were solitary tumor while 986 (23.5%) were multiple tumors. The histologic subtype, pathological grade and stage, the existence of vascular and lymphovascular invasion, tumor in situ, abnormal variants and rare subtypes were recorded and analyzed. Results 162 cases(3.9%)were benign tumors and 4 038 cases(96.1%)were malignant tumors including 4 008 cases of urothelial cancer (UC), 18 cases of primary adenocarcinoma and 12 cases of primary bladder squamous carcinoma. Furthermore, 2 460 (61.4%)cases were high grade UC while 1 548(38.6%)cases were low grade. 320 cases were found intravascular tumor embolus or lymphovascular tumor thrombus and 391(9.3%)cases were found metaplasia of squamous epithelium. Moreover, there were 230 cases of squamous differentiation, 120 cases of glandular differentiation, 110 cases of both squamous and glandular differentiation, and 39 cases(0.9%)of other rare subtypes or variations. On pathological stage, 112(2.8%)cases were carcinoma in situ, 548(13.7%)cases were Ta,2 599(65.1%)cases were T1,480(12%)cases were T2,92 cases(2.3%)were T3 and 23 cases(0.6%)were T4 stage, with the rest cases being unable to be accurate staging. Multiple Logistic regression analysis revealed that lymphovascular invasion was related to tumor grade , pathological stage and abnormal differentiation (P<0.02). Moreover, UC with squamous and glandular differentiation were related with tumor recurrence and progression (P=0.02). Conclusions Most bladder tumors were high grade and low stage urothelial cancer with various forms of differentiation. Squamous and glandular differentiation were most common variation which should be avoided to diagnosed as hybrid carcinoma. Lymphovascular tumor thrombus and abnormal differentiation were correlated with tumor stage and grade. Key words: Bladder; Neoplasm; Pathology; Urothelial neoplasms