It could be a patch of eczematous skin lesion known as lichen simplex chronicus
or lichen planus
To treat the same, application of steroid salicylic acid
ointment over the lesion and use of hydrating cream containing lactic acid and urea to keep the area intensively moisturised would help.
To make a definite diagnosis of your skin lesion, a dermatologist's advise is required. You may book an appointment for the same.
Hope that answers your query. Take care.