A gorch located on Worf's nose.
A gorch is a large and unsightly skin inflammation to which Klingon teenagers are prone, similar to the human skin condition acne.
In 2375, due to his exposure to the metaphasic radiation on the planet of the Ba'ku, Lt. Cmdr. Worf acquired a gorch on his nose, even though he was 35 years old. (Star Trek: Insurrection)
The use of the term "gorch", could possibly be a tongue-in-cheek reference to a short-lived series of Jim Henson-produced Saturday Night Live skits, which starred the warty, Muppet-like inhabitants of the planet Gorch.