Mishnayos Negaim Perek 6 Mishnah 6

אימתי – the outer [bright white spot on the skin] is pure when the inner [bright white spot on the skin] or the outer [bright white spot on the skin] has spread on the quick flesh, for we stated above that the outer [bright white spot on the skin] is pure (see the previous Mishnah), these words apply when it is exactly the size of a lentil, that the quick flesh is like an exactly defined lentil, not less and not more. But if the quick flesh is greater [in size] than that of a lentil, [the excess is a token/sign of spreading for the inner one (i.e., the bright white spot on the skin) and the outer one (i.e., the bright white spot on the skin) is unclean].

המותר סימן פסיון לפנימית והחיצונה טמאה – that is to say, if the inner [bright white spot on the skin] spread over that excess, both of them are to be declared to be definitive leprosy. The inner one because of the spreading and the outer one because of the quick flesh. But if the outer one (i.e., the bright white spot on the skin) spread over that excess, nevertheless, the outer one is to be declared definitive leprosy because of the quick flesh and the inner one is to [cause] to be shut up/isolated. But the Halakha is not according to Rabbi Shimon.

היה בוהק פחות מכעדשה (if the white scurf/tetter was less than a lentil) – near the inner [bright white spot on the skin], and the outer [bright white spot on the skin] surrounds the white scurf/tetter.

סימן פשיון לפנימית – if the inner [bright white spot on the skin] spread and covered the white scurf/tetter, the inner [bright white spot on the skin] is to be declared a definitive leprosy , for it has spread from the outside. But if the outer [bright white spot on the skin] spread and covered the white scurf/tetter, it is not a sign/token of spreading for the outer [bright white spot on the skin] for the plague does not spread within. And that it (i.e., the Mishnah) used the phrase: "היה בוהק פחות מכעדשה"/it was a white scurf/tetter less than a lentil -, for if it was like a lentil, it would defile because of the quick flesh for we hold that quick flesh defiles in all of the appearances [of plagues], but less than a lentil, there is no quick flesh, for there is no quick flesh that is less than a lentil.