Levítico 13:3

3 The priest is to examine the sore on the skin, and if the hair in the sore has turned white and the sore appears to be more than skin deep, it is a defiling skin disease. When the priest examines that person, he shall pronounce them ceremonially unclean.

3 and the priest shall look on the plague in the skin of the flesh: and if the hair in the plague be turned white, and the appearance of the plague be deeper than the skin of his flesh, it is the plague of leprosy; and the priest shall look on him, and pronounce him unclean.