Fifi is going to be fine.

It was a benign tumour and the vet just removed it. He wasn't really sure what caused it. She had a few days rest and Fifi is just back to her old self, although showing a bit more affection lately. I think the vet just always freaks out pets. Have you ever noticed even when a kitten hasn't been before it gets all nervous in the waiting room. It must be true they can smell the fear of the other animals.