Recently had a cystoscopy, found red spots on bladder. going in for biopsy but doctor feels may just be inflammation. what could that besides cancer?

Angiomas, cysts,....: Angiomas, hemorrhagic cysts, benign tumors ( eg an "inverted" papilloma), Hunner's ulcer (from Interstitial cystitis), irritation from the cystoscopy rubbing against the bladder (eg cystoscopy not being performed under direct observation, irritating the bladder wall before being visualized), incomplete or over distention of the bladder during cystoscopy,....

Likely benign: Inflammation of the bladder, commonly called Cystitis, is quite common especially in women. So a biopsy via the Cystoscope will be useful if you have persistent symptoms of frequent and painful urination. Cancer typically causes a growth which is easily visible through the Cystoscope and a biopsy can easily confirm it if its there, but it is unlikely if the red areas in the bladder are Flat in app