Leviticus 13:36-46

36 the priest will make another examination. If the scab has spread on the skin, the priest does not have to look for yellow hair. The person is unclean.
37 But if he sees that the scab hasn't spread and black hair grows on it, the scab is healed. The person is clean, so the priest must declare him clean.
38 "If a man or a woman has white irritated areas of skin,
39 the priest will make an examination. If the irritated areas on the skin are pale white, a rash has developed on the skin. The person is clean.
40 "If a man loses his hair, he is clean, even though he is bald.
41 If he loses the hair on the front of his head, he is clean, even though he is bald on the forehead.
42 But if there is a pink patch on the bald places in back or in front, a skin disease is developing in those places.
43 The priest will examine him. If the sore from the disease in the bald places in back or in front is pink like a skin disease somewhere else on the body,
44 the man has come down with an infectious skin disease. He is unclean. The priest must declare him unclean because of the skin disease on his head.
45 "People who come down with a skin disease must wear torn clothes and leave their hair uncombed. They must cover their upper lips and call out, 'Unclean, unclean!'
46 As long as they have the skin disease, they are unclean. They must live outside the camp.