Hi @buffalowy. Welcome to our group. HPV16+ or P16+ is usually a better diagnosis than "unknown" in that in the last twenty years we are finding the treatment can be a little less severe than the standard treatment for squamous cell carcinoma. That being said you are in for a bit of a challenge for the next few months and healing will go on for some time after that is usually the case.
I find it unusual that a PET scan is being run before you have surgery and treatment. Perhaps they are looking for other areas to examine as well because it was in your lymphatic system. At least you are getting to this early rather than most who get the diagnosis after months or years of suffering other issues caused by SCC.
If you have questions as you get started on your treatment please don't hesitate to ask. Were you told why they wanted to do a PET scan already?