Why are the Simanim on the area of a boil or a burn different than those on healthy skin?
Seforno: Because the skin that was removed via the boil or the burn cannot re-grow, in which what grew there is not real skin but a sort of substitute. 1
As the Gemara states in Nidah, 54a.
Why does it say "Levanah Adamdames"?
Rashi: This includes white and red mixed together.