I know exactly what you are going through with Cookie right now. Two years ago, we found a lump on the neck of our then 10-year-old kitty. It was right over his vocal cords and was really hard plus he had been meowing oddly for a couple of weeks. We rushed him to the vet and they told us it could be either a tumor, a cyst on his vocal cords or just an occluded area of drainage. When they tried to do a sample to see if it had liquid, it was too hard so they had to do the procudure to remove a piece and test it. We were lucky that it turned out not to be cancerous, and our baby kitty is doing very well with years of love left to us.
That week while we were waiting for results was sheer h*ll, but I tried my best to positive the whole time. Arkhe (read R-K) was very cuddly the whole time because I think he could sense how worried we were. I'm sure your puppy-girl senses the same thing from you and is seeking to both comfort you and get comfort from you.
My thoughts are with you as you take her in for her procedure tomorrow and I'm praying that everything goes as well as it possibly can. Hang in there!