Thanks for posting your query.
1.Your patch may be due to early psoriasis- If Silvery scales will be present.
2. May be due to chronic irritation - if you quite often kneel down during prayers or due to any other reason.
3. Pityriasis rubra pilaris
- Some sort deficiency or problem in absorbing Vitamin A
Consult your dermatologist
and have the treatment you will be alright.