TT #230 · Parshas Tazria · Aliyah 7 · Passuk 42
English: But if a white-reddish lesion appears on the bald area or the front bald area, it is an eruptive tzaraas on his bald area or front bald area.
Torah Temimah cites Sifra (Toras Kohanim) for the inclusion of healthy flesh as an impurity sign in bald areas.
English: The word “tzaraas” teaches that a lesion in a bald area can render a person impure through the sign of living flesh, even though the lesion is not subject to the white-hair sign.
Living flesh is a qualifying impurity sign in this category.
A sign of living flesh can establish impurity in a lesion on a bald area.