TT #73 · Parshas Tazria · Aliyah 1 · Passuk 2
English: When a person has on the skin of the body a swelling, a rash, or a discoloration, and it develops into a scaly affection on the skin of the body, it shall be reported to Aaron the priest or to one of his sons, the priests.
Chabad.org — Chumash, English translation + Rashi for Vayikra 13:2
Torah Temimah cites Sifra (Toras Kohanim) for the added requirement that the person’s distress is apparent to others.
Sifra — Vayikra 13, Midrash Sefer
English: “For a lesion”—others can also see that the person is distressed by it.
Textual inference
This unit adds an outward dimension to the previous one: the distress is not only privately felt but is also apparent to others.