My son has blonde hair with white spots on the back of his head is he losing pigment?

Vitiligo is a fairly common pigment discontinuity in people usually present since birth. It is usually only present in a few spots and the decreased, or lack of melanin can cause the skin to turn white. When present in hair it causes the hair to become platinum blonde despite the rest of the hair's color. Vitiligo is usually present from birth though can in some cases be acquired.