Hello,
I cannot confirm anything without examination but these white spots can be due to hand eczema, contact dermatitis, flat warts, pityriasis versicolor or vitiligo( less likely). Flat warts are about the size of a pinhead and usually appear
on the face, but can also appear
on arms, knees, or hands.Other possibility is of eczema. It is a form of chronic dermatitis (rash).Allergic reaction is one of the important causes of eczema.