TT #233 · 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 distinguishing naturally occurring baldness from baldness caused by illness.
English: The Sifra asks whether baldness caused by illness is included, and derives that the relevant baldness must be of the kind that occurs naturally.
The baldness categories concern naturally occurring hair loss.
The rule distinguishes naturally occurring baldness from hair loss caused by illness.