UROTHELIAL CARCINOMA IN SITU of the bladder features obviously anaplastic cells in a flat urothelium.
There may be full-thickness, obvious anaplasia. In this case, the urothelium actually tends to be thin, and the cells tend to come apart.
Or there may only be a few anaplastic cells among healthy-looking cells ("pagetoid").
* Future pathologists: A fooler is BK polyoma virus in the immunocompromised. Another is chemotherapy effect after mitomycin C and/or thiotepa. Let us worry about this.
Usually asymptomatic, CIS may be uncomfortable if it allows backleak of electrolytes, since the salty urine stimulates pain fibers in the submucosa.
On cystoscopy, if it is visible at all, it looks smooth and red (i.e., the lamina propria is inflamed because substances from urine leak through) or is sometimes detected only by sampling of the mucosa by biopsy.
Carcinoma in situ is notoriously unpredictable, and much more ominous than an actual mass lesion without invasion (J. Urol. 172: 882, 2004). Around 20-50% of known cases of carcinoma in situ turn into invasive cancer within five years (Am. J. Clin. Onc. 21: 217, 1998), and it can sometimes metastasize without an identifiable invasive mass. We believe that many (most?) invasive cancers start here rather than in papillary lesions; the numbers are still being sorted out.
This is from a pathologist...........Pat