Leviticus 13:18-20

18“If the body develops a boil in the skin, and it is healed,

19and in the place of the boil there comes a white swelling or a bright spot, reddish-white, then it shall be shown to the priest;

20and if, when the priest sees it, it indeed appears deeper than the skin, and its hair has turned white, the priest shall pronounce him unclean. It is a leprous sore which has broken out of the boil.