It bothers her. She can see it in the mirror and she's memorized where is it on her back, so she can trace it, and feel the disgusting, disfiguring tissue along her skin. She hates it, and no amount of makeup will make it go away.
She doesn't want to accept it, because it's ugly, and no one will accept her if she accepts it. She wants to hide it, so no one will have to see it, and hate it, and hate her. At the same time, it's a part of who she is.
So she can't accept herself.