Leviticus 13:9-13

9“When anyone has a defiling skin disease, they must be brought to the priest. 10The priest is to examine them, and if there is a white swelling in the skin that has turned the hair white and if there is raw flesh in the swelling,

11it is a chronic skin disease and the priest shall pronounce them unclean. He is not to isolate them, because they are already unclean. 12“If the disease breaks out all over their skin and, so far as the priest can see, it covers all the skin of the affected person from head to foot, 13the priest is to examine them, and if the disease has covered their whole body, he shall pronounce them clean. Since it has all turned white, they are clean.