[Question] Is there a way to restore my elbows, knees, and ankles when they turn black?

Areas that are often neglected, such as elbows, knees, and ankles, become rough.

There are times when it turns dark and black, and I hear there are various reasons for this.

It is said that pigmentation caused by environmental factors can be the cause.

Now that summer is here, wearing short clothes that expose elbows and knees can make it worse.

It probably doesn't look good. How should I maintain it? ? Should I get a consultation for a dermatology procedure? ?