Happened to my husband  on 2 occasions He had biopsies both times and each time it was inflamation Seems it is impossible to tell if a red patch is carcinoma in situ or inflammation 

There are quite a few posts on the Macmillan bladder cancer forum  about the "infamous red patches" Seems a bit uncommon problem after bcg

Best wishes 

Wilbert 

Thank you so much

Hope your husband is well

He has been bladder cancer free for 6 years thanks to bcg

Unfortunately repeated urine infections have led to discovery of cancer cells in his ureter 

Currently having mitomycin into the bladder to see if it helps Only good thing it is slow growing and a urinary stent has cleared the infection problem

best wishes

Wilbert