I had eczema too as a young child and had the same discoloration in the same place. I can tell you that the shading fades over time and is now completely gone. It has been twenty years (or so), but it didn't take all that time. You see, I cannot tell you how long it took because, frankly, I forgot about it and let life take its course. No one ever mentioned it to me and so it was something that didn't really matter after all. It might seem like a big deal now but try not to focus on it. All the best to you.