well.... my dad said something about it today... and it got me wondering, does anyone know?

You obviously first have to visualize the lesion or mole but these are the basic things we look for when screening for skin CA

A- asymmetrical shape of the lesion
B- borders that are irregular
C- change in color from previously or not same color throughout.
As you can see for example a mole is rounded,sharp borders and generally one color.

http://www.carpal-tunnel-symptoms.com

Black scary looking spots on your skin. a skin grapht will determine.

The only way is to have a doctor test for it.