ABSTRACT
This chapter summarizes the knowledge on in situ transitional cell carcinoma of the bladder. Most patients with carcinoma in situ studied so far have not come from screening programs, but rather have been patients with complaints referable to the lower urinary tract, mainly frequency and urgency of urination, dysuria, and hematuria. Mapping studies performed by systematic biopsy of the bladder and by step-sectioning of cystectomy specimens have provided much useful information on the distribution and extent of the mucosal abnormalities in the group of patients with bladder symptoms. No bladder had gross evidence of a neoplasm. Bladder mucosal atypia was evident about the borders of in situ carcinoma, usually with transition zones that featured a continuous gradation of change. This morphologic appearance is suggestive of a gradual extension of the borders of the neoplasm in the mucosa by a progressive process of evolution of premalignant atypia.
