Pathology of transitional cell carcinoma of the bladder and its clinical implications

Transitional cell carcinomas are divided into superficial and muscle-invasive tumors. Most of them are superficial tumors, and approximately 15-20% are muscle-invasive carcinomas. Pathologists play a significant role in diagnosing bladder tumors and in reporting features important for determining prognosis. We will review the cytologic and histopathologic features that help determine prognosis, including depth of invasion, tumor grade, multicentricity, tumor size, and the presence of vascular/lymphatic invasion, blood group antigen expression, proliferative indices, and molecular markers. Brief mention will be made of specimen handling, interpretation, reporting, and histologic variants of transitional cell carcinoma.