Parsha Mitzvot: Tazria: Mitzvah 172 – Concept 448
“Then he shall shave himself, but he shall not shave the nesek; and the Kohen shall quarantine the nesek for a second seven-day period (Vayikra 13:33).”The Metzorah must not shave signs of impurity in his hair (Rambam, Hilchot Tumat Tzara’at – The Laws of Impurity Through Tzara’at).
The Gimel of “v’hitgalach,” is written very large in the Torah to hint to the three people who are obligated to shave: a Nazir, Metzorah, and the leviim. (Ba’al ha-Turim)
Shaving can be an expression of achieving a new and more elevated status. The Metzorah is not permitted to shave his Nesek because one cannot achieve an elevated status by hiding his faults.