TT #118 · Parshas Tazria · Aliyah 2 · Passuk 10
English: It is chronic leprosy on the skin of his flesh, and the priest shall pronounce him impure; he shall not isolate him, for he is impure.
Chabad.org — Chumash, English translation + Rashi for Vayikra 13:11
Torah Temimah cites Sifra (Toras Kohanim) for the status of chronic tzaraas even when the lesion’s appearance has changed.
Sifra — Vayikra 13, Midrash Sefer
English: “It is long-standing”: the lesion can render a person impure whether its appearance has changed to the opposite shade or remains unchanged.
Textual derivation
A long-standing lesion retains its impurity status whether its appearance has shifted to the opposite shade or remains unchanged.