TT #232 · 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 excluding white hair as an impurity sign in bald areas.
English: The word “it” excludes white hair as a sign of impurity in a bald area. The Sifra rejects the inference that, because living flesh applies there, white hair should apply as well.
White hair is not the diagnostic impurity sign in this special case.
White hair does not establish impurity for a lesion in the bald area.