Itching and varying degrees of erythema may precede or accompany the development of the characteristic depigmented ring of the halo nevus (HN). The halo is several millimeters to centimeters wide and surrounds a preexisting pigmented nevus (Fig. 38-1). The halo usually reaches its maximum size in 1 or 2 months, after which the central nevus slowly diminishes in size and over a period of months or years tends to disappear. The depigmented area eventually resumes its normal color. The condition is common and usually occurs in children and young adults. The incidence of HN is high—nearly 25%—in patients with vitiligo, and HN may be a forerunner of that disease.