Carcinoma in situ of the bladder is a type of cancer. Carcinoma in situ in other parts of the body, such as the prostate, cervix, or testicle, is thought to be a premalignant condition, but in the bladder it is always malignant. If untreated, 50% of cases will progress to muscle-invasive cancer within 5 years, and thus carcinoma in situ needs to be taken very seriously. The rate of pro-gression to invasive cancer is even worse for those patients who also have a papillary bladder tumor.
Carcinoma in situ itself is a flat (not papillary) lesion, and thus it can be more difficult to identify during a cystoscopy. It may appear as a red, irritated patch or may be indistinguishable from normal, adjacent bladder. If a patient is at high risk for carcinoma in situ, most urologists will take random biopsies of the bladder to screen for this disease even though the bladder may appear normal at the time of the cystoscopy. Carcinoma in situ tends to shed cells into the urine, which can usually be detected on a urine sample by a test called urine cytology .