It would be highly unusual for an HPV positive oral cancer to produce a new second primary like this, at least from the people that talk with at treatment institutions, and what they tell me about their patient populations anecdotally. I vote for a cyst, which is a highly common occurrence in the general population, but in your case they are just be vigilant and careful.

Also a single spot, vs the long lesions that are more common in actual liver cancer presentations, seems like a good thing to me. Last, if it were a cancer, and it is localized to one spot, that could be excised quit readily through a laparoscopic procedure. The liver is the only essential organ that can actually regenerate parts of itself after a small section is excised.