Weird line of skin on hand

[AmyGurumi3]

Hi, I have this weird line of skin on the side of my hand that is dry and slightly darker than the surrounding skin.

I went to the doctors with it when it first appeared (a few years ago) but he literally just glanced at it and prescribed me some moisturiser which did nothing, so I just ignored it after that.

It gets itchy sometimes, and it bugs me that I don't know what it is. Does anyone have any idea? I've put some links to a couple of photos of it.

Thanks

s27.postimg.org/f2g80oxqb/DSCN1279.jpg
s27.postimg.org/dool5dygz/DSCN1281.jpg

I've got the exact same on my foot in two places. It's a line of thick skin on an otherwise non dry foot. I've been picking at it but it comes back and moisturisers aren't helping at all. I haven't been to docs as it's the least of my worries just now but I'll keep an eye on this thread for any suggestions!