Dark patch of skin on dd1's kneck?

[Marne]

I thought it was dirt but when i tried to wipe it off it didn't wipe off. It almost looks like she's caught the sun/sun tan. What could it be?

It can't be a birth mark or i would have noticed before.

It could be a skin re-action/allergy.

If doesn't clear up or you are very worried, pop her up to the doc's.

if it has smooth edges then there is probably nothing to worry about but i was told that if it had really jagged irregular edges to get them looked at. Could just be a cafe au lait freckle