Cover up makeup for my mom's poor arms

My mother has some fairly dark red/purple spots on her arms that she is quite self conscience of. They have formed because of all the steroids she has had to take has made her skin very thin. Anyway, I was wondering if anyone had any suggestions on makeup that might be able to cover up these spots it well, it would be greatly appreciated. We have heard they make makeup to cover tattoos... anyone every tried that or have a brand they like? Thanks!