Carcinoma in situ and dysplasia of the bladder urothelium

Summary

Urothelial carcinoma in situ (CIS) is a high grade noninvasive malignant tumor which involves most commonly but not exclusively the transitional epithelium of the urinary bladder. Despite its relatively innocuous cystoscopic appearance, CIS is rarely an incidental finding and most patients present with symptoms of urinary tract disease. The majority have previous or concurrent bladder cancer; primary CIS does occur but is uncommon. Detection of CIS is best accomplished by urinary cytologic examination. Experimental studies have shed light on the development of CIS, but its biological potential in the spectrum of neoplastic transformation remains unclear. The prognosis of patients with CIS is variable: many develop invasive carcinoma while others continue for years without disease progression. Urothelial dysplasia represents a distinctive pattern of morphologic alteration characterized histologically and cytologically as atypia which deviates from normal to a mild or a moderate degree. Like CIS, most information concerning urothelial dysplasia has been obtained from experimental studies in laboratory animals or from patients with bladder cancer. Preliminary evidence indicates that dysplasia may be a precursor lesion in the spectrum of developing carcinoma. While both experimental studies and clinical observations suggest that urothelial carcinoma arises through a series of progressively severe cytologic and histologic changes, these events are not necessarily an inevitable continuum in human patients and further definition of the relationship of dysplasia and CIS to invasive urothelial cancer is required.