Dog Just had Grade 4 Mass Removed

My dog had surgery to remove a mass on his elbow. I have noticed a lump a few months ago, and it continued to grow. We have finally come out of surgery yesterday to have the mass removed and looked at. It is so hard to see your best friend go through the downs of coming off of anesthesia and being on medication. The vet said that she was overall concerned with the mass, most noticeably how fast it grew within the span of a few months. She shared that she thinks, (or is?) a nerve sheath tumor. Has anyone had any experience with that? I am looking to hear about your experiences with that and how your pup was.