Sore on Paw. Little crater; plantar wart?

Hey All,

My kitty has a sore on one of his paws. It's a dry spot that's like a little crater that goes into the pad. Almost reminds me of a human plantar wart. See in the pic below how it has raised edges around?

I gently scraped at it, thinking that he might have picked up a sliver or thorn of some type, but it doesn't seem to have anything stuck in there. When I scraped it kitty was really good. He didn't struggle, but gave me a little "ouch!" squeak, so I fear that it might be causing him discomfort.

I also washed it with soap and water, and put a little olive oil on it.

Note that the light spot closer to the center of the paw is just his natural coloring. 

High resolution here (2.2mb):

http://www.miklas.org/images/catPawSore.jpg

Any ideas? Thank you! I'm worried. 

If it's sore to the touch, you might want to have a vet look at it.  She may have something stuck in there that is causing the ulceration.  If it's just the one paw pad, it's unlikely to be "pillow foot" but if it has been around for awhile and is not healing, do get the vet to check it out.