I have a very small light spot on my hand
Regarding a white spot on back of hand
Hello and welcome to ask a doctor service. I have viewed the image and gone through your query.
I would keep a possibility of either Idiopathic Guttate Hypomelanosis (IGH) or Vitiligo. If I was the treating doctor I would suggest that you try a moderately potent topical steroid e.g either Triamcinolone acetonide cream 0.1% or Mometasone furoate cream 0.1%, for a few weeks.
Hope I have answered your query. Let me know if you need any more assistance.