She has a mast cell tumor, basically cancer. There's about a 50/50 chance it will come back. The only way they know they could have prevented it if they would have done a biopsy first, and they would have had to remove most of the muscle in her leg, basically crippling her. He did the best option he could have done, and he took out a good portion surrounding the tumor too, just not the muscle.
We will know in about 6-8 months wether or not it will reoccur, as that's when they start popping up.
We just lost out cat of 14 years to cancer back in August, so I'm taking it pretty hard.