I read that there are several layers (mucosa and submucosa) before the muscle, so it maybe that the tumor did not penetrate these mucosal and submucosal layers and they see clear margins without muscle. Maybe the urologist did not want to make a big injury in the bladder wall without necessity. The main question to ask your urologist is do they see clear margins on the biopsy.
Then how can they state non invasive if they didn't have muscle included? You have provided me with so many answers the past eight months. I want to thank you, I have been online for hour's trying to get the answer.