Nevus  is typically a bluish or gray-brown lesion .This serious cosmetic problem occurs in 0.6 percent of Japanese,' but is also seen in Chinese, East Indians, blacks, and white. Treatments have included surgical removal, skin grafting, dermabrasion, and cryotherapy.
Surgical treatment causes scarring, and cryotherapy, although it may be somewhat effective depending on the site of the lesion, is not reliable and may cause atrophy or scarring if over applied.
Selective photothermolysis produces specific, heat-mediated injury to pigmented skin cells and other structures by means of brief and selectively absorbed laser pulses.1,5 Melanin, the pigment in melanosomes, is a potential target for selective photothermolysis, because it is the primary light-absorbing compound of cells exposed to laser energy of a certain wavelength. The Q-switched Nd: YAG laser can produce very short high-energy pulses and can selectively target cells that contain pigment, such as dermal melanocytes

 Technique

The patients are treated either without anesthesia or with topical anesthesia (5 percent lidocaine
hydrochloride ointment). During all treatment sessions, the eyes of the patients and the clinical
staff are protected. The treatment intervals ranged from 6-8weeks  

 Results

Clinical Course
A white square appear immediately after pigmented skin was exposed to the Q-switched Nd;YAG
laser.. A wheel-and-flare response is seen around the irradiated sites about five minutes later. This response is pronounced when periorbital areas are treated. The whitening.was more intense in pigmented skin than in the surrounding skin. This white color fade within about 20 minutes.

Superficial punctate erosions limited to the pigmented area was seen in some patients immediately after laser treatment.

The wheel-and-flare response last for several hours, and erythema is seen for upto 24 hours.
Periorbital edema sometimes persist for two or three days. Vesicles are occasionally seen during the first three days after laser treatment followed by formation of a brown crust over the treated pigmented area during the first two weeks. Gradual lightening of the lesions is usually evident after two or three laser treatments. Dermal tissue in nevi of Ota contains large amounts of melanin, which provides an excellent target for the laser.
The Q-switched Nd:YAG laser appears to cause selective destruction of pigmented cells, with negligible damage to surrounding tissues. The Q-switched Nd: YAG laser is also useful in removing tattoos, in particular those with blue-black pigment . Multiple treatments increase the response rate.