Leviticus 13:18 (KJV)

Or if the raw flesh turn again, and be changed unto white, he shall come unto the priest;

And the priest shall see him: and, behold, if the plague be turned into white; then the priest shall pronounce him clean that hath the plague: he is clean.

The flesh also, in which, even in the skin thereof, was a boil, and is healed,

And in the place of the boil there be a white rising, or a bright spot, white, and somewhat reddish, and it be shewed to the priest;

And if, when the priest seeth it, behold, it be in sight lower than the skin, and the hair thereof be turned white; the priest shall pronounce him unclean: it is a plague of leprosy broken out of the boil.