When you sign up to be an organ donor, you don't get to pick and choose which parts of you they use. Everything is up for grabs, so to speak. I would imagine facial skin is one of the most difficult organs to transplant b/c not only do you have to worry about the normal things (blood type compatibility, rejection risk, etc) but I would think you've also got to look at bone structure and tissue markers for both people to make sure it will all work.
I remember when the attack happened. It was absolutely horrific. That poor woman...I'm so glad she was able to have the transplant.