its the same as my daisy had you have discribed it the same way as i did down the phone to the vets so it seems to me like its a tumor, they can operater on it although its (as all operations on small animals) not 100% they will pull thu, and also the tumor might come bk, but dont just take my word plz talk to you vet and ask about options, i hope it all works out for you! keep me updated