Introduction to removing unwanted
pigmented skin lesions using lasers
Pigmented skin lesions are very common. In the
U.S., out of millions of cases only a few are treated.
However, they represent large absolute numbers
and cannot be ignored because great expense of
time and effort is involved. The medical problems
and emotionally debilitating cosmetic issues are
equally important factors in deciding treatments.
Types of pigmented skin lesions
There are three types of skin lesions according
to the site involved.
- Epidermal lesions,
commonly seen and includes benign melanocytic
lesions, freckles and benign nevus
- Epidermal-dermal lesions, which includes compound
nevi, Becker’s nevus and melasma.
- Dermal lesions, which includes blue nevus
and intradermal nevus like, pigments in most
All laser treatments of these lesions attempt
to selectively destroy the responsible pigment
only, with minimum side effects. CW CO2 and Nd:
YAG lasers have been fairly successful, but due
to their less targeted application cause epidermal
damages producing side effects, such as, permanent
hypopigmentation, atrophy, scarring and skin texture
changes. Non-targeted treatment of dermal lesions
is now considered risky.
Subsequently, selective photothermolysis was used
with pulsed lasers and has shown significant improvement
over the earlier methods of treatment. The destruction
of targeted chromaphores was more selective. The
melanin in the pigmented lesions is the target
chromaphore in this process. Melanin is present
inside melanosomes. Narrow pulsed lasers at wavelengths
between 600 to 1200 nm penetrate more and cause
more selective destruction. Mostly Q-Switched lasers
with their relatively shorter duration pulses have
been found more effective in removing pigmented
Laser treatments used in pigmented
skin lesions - study results
Q-Switched Ruby laser or QSRL: QSRL operates at
narrow pulse widths and 693 nm wavelength, ideal
parameters, theoretically, for destroying skin
pigments. However, it is known to be melanin specific
and melanin dependent.
Treatment of the epidermal lesion, lentigo, gave
excellent results at certain fluences, on almost
all racial groups, though Hispanic patients proved
more difficult to treat. No permanent side effects
were seen. QSRL proved as good as PDL in treating
lentigo. Another epidermal lesion, café-au-lait
patches, also gave good but not as good results
as in lentigo treatment. However, fewer side effects
showed there were improvements over non-pulsed
laser treatments. Café-au-lait patches are
normally very difficult to treat. Melasma, an epidermal-dermal
pigmented lesion, gave widely varying response,
so that no definite conclusions were possible.
The dermal lesion, nevus of Ota, was successfully
treated by QSRL, needing lesser treatment sessions.
Despite needing multiple treatments, the results
were always excellent.
Recently, QSRL was found effective in treating
infraorbital skin darkening, judged clinically
to be due to melanin. Other lasers like, Q-Switched
Nd: YAG and alexandrite may be as effective in
treating infraorbital lesions, but QSRL causes
less scarring and permanent textural changes.
To sum it up, QSRL is very effective in treating
all kinds of benign pigmented skin lesions. While
other pulsed laser systems may be equally effective,
the QSRL is unmatched in its versatility. The fact
that, besides epidermal lesions, it can also successfully
treat epidermal-dermal and dermal lesions, speaks
about its effectiveness as also its flexibility.
Nd: YAG laser: The QS-Nd: YAG laser, with its
high powered and narrow width pulses, allowing
accurate chromaphore targeting, has been found
very effective in treating superficial epidermal
pigmented lesions and tattoos. QS-Nd: YAG laser
is especially effective in treating freckles and
lentginious lesions. The side effects are minimal.
Whitening and purpura occur, but last only 5 to
6 days. Only one treatment is enough for these
lesions. However, patients need to avoid sun re-exposure,
since these lesions do recur.
QS- Nd: YAG can also successfully treat café-du-lait
in three or fewer treatments. But the response
of café-du-lait to laser treatment varies.
The lesion may lighten, darken or clear. More treatments
may be needed to get the desired results. Appropriate
fluences are important in café-du-lait because
too low fluence may cause hyperpigmentation and
too high fluence may cause scarring.
Becker’s nevus, a hairy patch on a man’s
chest or shoulder also responds well to QS- Nd:
510-nm pulse dye laser (PDL): This laser was developed
for treating epidermal lesions. This treatment
is now recommended for café-du-lait, lentigines,
Becker’s nevus, nevus of ota, melasma and
post- inflammatory hyperpigmentation.
Alexandrite laser: The alexandrite laser, operating
at 760 nm, was designed to penetrate the dermis.
It is therefore now used to treat dermal-pigmented
lesions. It would seem that this laser, operating
at 760 nm wavelength would be less selective in
targeting chromaphores. However, it has proved
effective in clearing some kinds of dermal-pigmented
lesions, such as, post inflammatory hyperpigmentation.