(Or so I'm told. So far I've been able to avoid experiencing one myself.)
I was an embedded engineer at an RF company and it sort of comes with the territory. We had technicians who had lasted 4+ decades in RF (same company, actually) with scars to show for it. Same story, mostly on their fingers from accidentally hitting hot spots.
I was burned by ~300W in the specific cases I mentioned. I think it probably classifies as second-degree burns and (because I was young and dumb) I never did anything to help prevent scarring or heal the tissue besides basic first-aid. Safety first, everything else is secondary.
Actually, now that I think about it, it'd actually be most similar to how a microwave heats meat, wouldn't it? Microwaves being within the RF part of the EM spectrum and all. (Though not quite the same, given the lack of dipole interaction with water molecules outside of the particular part of the spectrum microwaves sit on.)
I was told this story by my grandmother to prevent me from watching food cook in the microwave. That and cataracts, which can also be caused by heating up things that shouldn't be heated.
The turntable in my microwave failed when I heated up a frozen pizza, and the result was part of it was burned, and part of it was still frozen.