Which of the following cystoscopic descriptions of bladder tumors is false?

A. nodular or sessile lesions usually invade muscle

B. papillary bladder tumors are typical of low stage and grade

C. carcinoma in situ appears as a flat, velvety patch

D. sarcomas commonly invade bladder base and ureteral orifices causing obstructions

Please do not use chat terms. Example: avoid using "grt" instead of "great".