TT #239 · Parshas Tazria · Aliyah 7 · Passuk 45
English: As for the person afflicted with tzaraas, his garments shall be torn, his head shall be unkempt, he shall cover his upper lip, and he shall call out, “Impure! Impure!”
Torah Temimah cites Megillah 8b for the limited difference between a metzora under quarantine and one definitively declared impure.
English: There is no difference between a metzora under quarantine and one definitively declared impure except for the requirements of letting the hair grow and tearing the garments.
Textual derivation
In the rule discussed here, the only difference is that a confirmed metzora must let the hair grow and tear the garments; these requirements do not apply in the same way to a metzora still under quarantine.