General :: White TPU Case Discoloring?

I have a white phone and went with a white case which might have been a mistake. The case is turning blue from putting the phone in the back pocket of my jeans. Washing the case and scrubbing it with a brush, soap and even trying a little bleach didn't make it white again.

Any tricks to make it white again?

I was prepared to have to wash dirt off every once and a while but didn't realize this would be a problem. It's the androidified case but likely common to all TPU white cases. Something else to think about and likely avoid a white TPU case.