That explains it. If they are going to try to take a piece of the tissue, they probably prefer anesthesia. The specialist is going to do the procedure, right? His bloodwork was fine, which is great and the vet will know how to monitor your cat while he is under. I know that this is scary, but I agree that I also don't see many other options aside from proceeding and determining exactly what is going on. Get all the details about post op, especially if they do biopsy. Let us know what happens.