Been a while since I've seen this, but (someone correct me if I'm wrong) I seem to remember it's a torture burn.

From the QOS wikia page:

"When she was a young girl, the opposition in Bolivia sent General Medrano to her house; there, Medrano shoots Camille's father, rapes her mother and sister before strangling them to death, and then smiles at Camille before leaving and setting the house on fire, which is the cause for the burn scars on Camille's back."

I was waiting for someone to say it was an allergic reaction to Craig's touch .... haha... but I guess we're not at that level of delusional Craig Bond hate in this forum... yet. ;)

Well not from me, I love Craig's Bond!

Thanks for the answers to my question.

It also speaks to why she cowered in the burning building after killing Medrano — she was flashing back to being a child in the fire that destroyed her home. Bond comforted her with the same posture he comforted Vesper.

But, note - whereas, in Casino Royale, Bond comforted Vesper in water (the shower) but could not save her from drowning in water, here in Quantum of Solace, he comforts Camille in the fire, and then saves her from the fire.

Vesper represents loss for Bond; Camilla is a kind of redemption for Bond.

@DRDMovieMusings: Very good post! I completely agree with you.