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
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
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.