Hello,
If the white patches are dry and itchy then there is a possibility that these patches are due to lichen simplex chronicus. But if they are white depigmentation then vitiligo needs to be ruled out. It is a pigmentation disorder in which melanocytes (the cells that make pigment) in the skin are destroyed. The exact cause is not known but a genetic or hereditary predisposition has been seen.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.