20 The priest is to examine it, and if it appears to be more than skin deep and the hair in it has turned white, the priest shall pronounce that person unclean. It is a defiling skin disease that has broken out where the boil was.

Read Leviticus 13:20 Using Other Translations

And if, when the priest seeth it, behold, it be in sight lower than the skin, and the hair thereof be turned white; the priest shall pronounce him unclean: it is a plague of leprosy broken out of the boil.
And the priest shall look, and if it appears deeper than the skin and its hair has turned white, then the priest shall pronounce him unclean. It is a case of leprous disease that has broken out in the boil.
If the priest examines it and finds it to be more than skin-deep, and if the hair in the affected area has turned white, the priest must pronounce the person ceremonially unclean. The boil has become a serious skin disease.