Weird patch of skin?

I have a weird path on my arm that’s been there for the past few months and I’m not sure what it is. It doesn’t itch, here’s a photo. It’s a lighter, white patch with redder skin on the edges. It’s hard to see in the photo, but The redder skin is kinda flakey, like it’s dry. I tried putting moisturizer on it and it doesn’t help. There’s no irritation at all and I don’t remember anything happening to me on my arm. Does anyone have any idea what it is?