Leviticus 13:12-14

"'And if leprosy breaks out all over the skin, and the leprosy covers all the skin of the one who has the sore, from his head to his foot, wherever the priest looks.'"

"'Then the priest shall consider; and indeed if the leprosy has covered all his body, he shall pronounce him clean who has the sore. It has all turned white. He is clean.'"

"'But when raw flesh appears on him, he shall be unclean.'"

(All of chapter 13 details the Law Concerning Leprosy.)