וְאִם־תֵּרָאֶ֨ה ע֜וֹד בַּ֠בֶּגֶד אֽוֹ־בַשְּׁתִ֤י אֽוֹ־בָעֵ֙רֶב֙ א֣וֹ בְכָל־כְּלִי־ע֔וֹר פֹּרַ֖חַת הִ֑וא בָּאֵ֣שׁ תִּשְׂרְפֶ֔נּוּ אֵ֥ת אֲשֶׁר־בּ֖וֹ הַנָּֽגַע׃
And if it appear still in the garment, or in the warp, or in the woof, or in any thing of skin, it is breaking out, thou shalt burn that wherein the plague is with fire.
Rashi on Leviticus
פרחת היא IT IS A SPREADING PLAGUE — it is a thing which breaks out again and again.
Rashi on Leviticus
באש תשרפנו THOU SHALT BURN IT IN FIRE — “it” — the entire garment (in contradistinction to v. 56).