A:
This could be vitiligo. This is a condition in which there is loss of color in the skin and/or hair. There are other more rare conditions that can do this. And sometimes people have a white patch of hair for no particular reason.
I recommend that you take your child to see a doctor. Vitiligo and some of the other conditions that can cause this may be associated with other health problems, so it's a good idea to get your son checked out. That's the best way to figure out what's going on, and if any further tests are needed.