When you say that the area feels like it is under pressure, that is a good indicator of infection and abscess. Also the lack of high suv values on the PET in the area is encouraging. If this is what it turns out to be, I would highly recommend a root canal and draining combined with appropriate antibiotic treatment as a first course of action. Keep the idea of an extraction in reserve until it has to be done. That will mean 02 dives prior to extraction and the danger of a non-healing wound after the extraction is done. On a common radiograph/panorex the dark area of an abscess at the tip of a root is pretty easy to distinguish. Bone tumors will be more diffused in size and sometimes have what they commonly refer to as soap bubble radiolucency, which looks very different from a very circumscribed dark area at a root tip for an abscess.