Pathology Most bladder cancers are carcinomas of the transitional epithelium of the bladder's mucosal lining. Tumors are graded according to the degree of cellular abnormality, with the most atypical cells designated as high-grade tumors. Staging of this cancer is based on the depth of invasion into the bladder muscle and surround structures. One of the management problems is the carcinoma of the bladder frequently multifocal. The entire bladder epithelium and the lining of the entire urothelial cell tract can undergo malignant change.
Most bladder tumors are papillary transitional cell carcinomas.
Grade 1 represents well-differentiated papillary tumors with limited atypia and mitoses. At the other end, Grade 3 lesions show a marked increase in the cell layers and cell size, and noticeable pleomorphism and mitoses are prominent. In some classifications, the tumors are graded on a scale of I to IV, although the behaviors of grade II and IV tumors are so similar that the WHO has combined these two grades into Grade 2. Tumor grade appears to correlate significantly with the natural history of transitional cell carcinoma. The higher the grade of the diagnosis, the higher the incidence of death from the disease within two years.