To my knowledge, there are no data on the frequency of HPV on the buttocks; I doubt it has ever been studied. As discussed above, even if such infection were present, the transmission risk probably was extremely low.
What I mean by the above is assuming that she did have an infection in that region.
Thanks!
To the point of where the infection is - I know you may not be able to answer this, but how likely would it be for an infection to be on the buttocks (outside of the anus)?
Welcome to the STD forum.
Thanks for reading up on HPV before asking your question. You are correct about the frequency of HPV and its inevitability. Probably you ask this question because you also know that HPV is one of those STDs that can be transmitted by skin-skin contact, and therefore the risk from sex without penetration may be higher than for some STDs, like gonorrhea, chlamydia, or HIV. All that is true.
However, that doesn't mean the risk is high from this sort of exposure. The large majority of genital HPV infections are transmitted through vaginal or anal intercourse, usually unprotected by condoms. Further, it is safe to say that if your massage partner had genital HPV, it probably doesn't involve her buttocks. However, there are simply no data on which to estimate the numerical odds you were infected. I would guess it is well under 1 chance in 1,000 -- but that's about all I can say.
I hope this helps. HHH, MD