Dark patch of skin on the inside of my foreskin

First off, I'm white, and my penis is a little darker in colour than the rest of my skin. I am uncircumsised, and over some time i have noticed a patch of skin under my glans (on the "inside" of my foreskin) getting darker than the rest of the skin on that area. I didn't eventually think anything of it so i cant really say how long it has been like this, but this week I suddenly got a little freaked out by this. Does anyone have any idea what it could be? It is not itchy or anything like that, but I have had balanitis earlier. Could this be related to that?

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any new updates? have you seen a dermatologist?