Pigmented skin treatment with lasers

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 cell tumors.
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 nevus.

Laser treatments

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 skin lesions.

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: YAG.

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.