White spot on neck and chest?

I noticed that I have white spots on my neck and chest. I’m pretty tan, but in certain spots, I have skin that is much much lighter than the rest. It looks really weird, and it started from only being on my chest to being on my neck as well. Does anyone know what this is? Could it be from the tanning bed? It’s very noticable. I look like I have white spots all over me.