[quote=@KatherinWinter]
[@Framing A Moose] ok.... why...?
[/quote]

Because all of her insides are made up of fire and lava. That's why she puked lava. Getting bruised would damage her skin, which is the only thing keeping her insides from spilling out and damaging everything around her. Getting bruised would make the barrier between her insides and the outside thinner, and, in addition, would draw more boiling blood to the bruised spot, therefore her bruise would be burning hot.