When you think of skin cancer, you probably think of checking head to toe for moles. But did you know ... a dark black or brown line across a finger or toenail, according to the AAD.

Kelly Heather, 38, ended up needing brain surgery for a tumor — and it started as a discolored line on her fingernail Kelly Heather / SWNS (2) Kelly Heather, 38, first noticed a dark line on her ...