that might be the best explanation so far

Which one?

1. Alien Reptilians?

2. Humans molesting lizards underground?

3. Mutating naturally?

4. Vault/Lab experiment?

http://images.wikia.com/fallout/images/a/af/Spore_carrier.png
http://images.wikia.com/fallout/images/4/4c/Tunneler.png
http://images.wikia.com/fallout/images/5/5e/Trog.png
http://images.wikia.com/fallout/images/f/f7/Glowing_one.png

All are humans affected in some way by radiation and [-] sources, the example for a tunneler is a long life living under ground, in fully irradiated lands and in complete darkness. Then you just add Science! and you pretty much have them sorted, like the rest of the mutants.

Now that you show that picture, it doesn't look like its skin is scales just bumpy, scales really look like that. It looks more like an elbow that has really rough skin, it turns brown and is sort of like a few blobs.

This is something like it http://www.gcarlson.com/DisplayImage.php?ImageID=12 so the dry skin expands all over the body, and comes in a scale shape.