I Have Small White Lines On My Right Arm. They're

I have small white lines on my right arm. They're not welded, and don't hurt, and they've been there for a while from what I can tell. They look almost like scars from self-harm, but I've never cut myself or anything, so I don't think that could be it. There's several of them, and they're very thin and crisscross each other in several places, only appearing on my right arm, not my left. What are these?