can dermatologists remove tan lines?

i have a tan line under my arm like near my underarms and it's weird cause i never tan there at all i dont even go tanning. so the tan line is distinct (its basically like someone drew a line there and coloured the rest) i plan to visit the dermatologist and was wondering about how the dermatologist would go about removing the "tan line"? i wanna do some research before hand, thanks!