It could be a fungus infection. Check the skin for anything resembling ringworm or infected skin. Possibly missing patches of hair. Also look at skin folds for irritation.
Have you noticed any other changes, in his eyes for example, or on his coat? Does the hair on his coat generally look much much whiter than usual? Or does it have white patches?
How are his eyes? If they look cloudy or inflamed as well, then it would be a good idea to take him to the vet.
It's unlikely to be this, but if all those changes have taken place, as well as the lightening of his paws and claws, then it is just possible he could have an auto-immune syndrome called "VKH-like Syndrome" (also known as Uveodermatological Syndrome) and will need treatment.
It probably isn't this. I don't think VKH is that common. However I would say that if you are really concerned or notice any other changes take him to the vet. Keep a careful watch on his eyes. If you notice they look cloudy or blood-shot, take him to be examined.