7 year old Boxer has a boney protrusion on her face

My girl has a sizeable boney lump under her right eye. Its bigger than a quarter. I poked and prodded it, no reaction. I'm wondering if it could be dental related? The dog has not had any health problems (except a slowing thyroid). I'm silently freaking out because I fear the big "C" given her breed and age.
Any ideas? She's got her vet appt lined up for next week.

One of my cats had a tooth abscess that did the same thing. He got his teeth cleaned and a round of anti-biotics and it cleared up. I thought they'd have to pull his tooth but they didn't.

I could push on his face, too, and not get any reaction. That thing was hard as a rock!