TT #214 · Parshas Tazria · Aliyah 5 · Passuk 37
English: If the netek remains unchanged and black hair has grown in it, the netek is healed; he is clean, and the priest shall pronounce him clean.
Chabad.org — Chumash, English translation + Rashi for Vayikra 13:37
Torah Temimah cites Sifra (Toras Kohanim) for the inclusion of black hair that is not fully embedded within the netek.
Sifra — Vayikra 13, Midrash Sefer
English: 'Grew in it': even if the black hair is not completely embedded within the lesion.
Textual derivation
The protective effect of the black hair does not depend on its being completely embedded within the netek.