Its hard to see the area you're talking about because of the flash hitting that exact spot.

From what I can see it is either a natural patch or maybe a slight burn. If it has a texture to it I would say its a safe bet its a slight burn. If not, then it is probably just its coloring.

If it is textured or dry compared to the rest of the skin you need to check you setup as it would appear you have a heat lamp or che that is creating a hotspot that is way to hot.