Skin disease laser treatments are differentiated from laser treatments of other diseases by their increasing use of the advanced laser treatment known as photodynamic therapy, or PDT, and the advanced laser system, called, the excimer laser.

Photodynamic therapy (PDT) using excimer lasers

The therapy consists of a laser light, a photosensitizing agent and oxygen. PDT is able to remove tumors with reasonable patient tolerance and short healing time, compared to traditional surgeries. Initially, photosensitizers often induced phototoxicity. The latest photosensitizer, 5-aminolevulonic acid, shows substantially reduced phototoxicity. However, they have limited penetration. Photosensitizers with greater penetrations are under development.

The 308nm excimer laser is the latest laser system. It emits wavelength from the ultra violet-blue spectrum and selectively targets lesions. Advantages offered by the excimer lasers have been exploited to treat psoriasis, vitiligo, and several other skin diseases. Earlier, high fluences gave excellent results but with a high level of side effects. Lower fluences are now being used to avoid side effects. Numerous studies have confirmed the efficacy and tolerance of excimer lasers. However, since prospective studies are lacking, it still needs to be used with some caution.

Actinic keratoses (AK) treatment

Evaluation of the effectiveness of laser therapy in AK is incomplete. Anecdotal studies contradict each other. However, PDT in AK has been successful and is rapidly becoming a recognized treatment for non-hyperkeratotic AKs. Trials with various lasers showed that the 585nm long pulsed dyed laser gave the best results. In a study comparing cryotherapy with PDT, cryotherapy gave a better response rate but the cosmetic outcomes and patient satisfaction was better in PDT. It is believed that multiple PDT treatments may improve response rates.

Basal cell carcinoma (BCC) treatment

A review of several studies shows that PDT in BCC is comparable to radiation therapy. But PDT, with higher recurrence rates, remains inferior to traditional surgery where recurrence rates are around 10%. Pain was a common side effect in all studies. On current performance, laser therapy and PDT have limited use in BCC. However, multiple treatments and more penetrating photosensitizers, may give better results in superficial BCC. Even so, at present, PDT in BCC is currently reserved for only those who cannot undergo surgeries.

Squamous cell carcinoma (SCC) treatment

Studies of laser therapy and PDT in SCC give unclear results. A study of CO2 laser treatment of SCC showed residual tumors in most cases, indicating that CO2 laser treatment alone was not sufficient. A small trial of PDT treatment of SCC showed a response rate of 85%. The results were particularly encouraging in lesions of older patients with poorly vascularized skins. Some have suggested that PDT be considered the first line of treatment for SCC. Few comparative studies have shown laser therapy or PDT as distinctly superior to other treatments. In SCC, the risk of metastatic disease probably limits the use of lasers and PDT.

Psoriasis treatment

Taking advantage of the selectivity of the excimer laser, higher fluences were experimented. While the results were excellent, side effects, such as, severe pains due to burns and blisters were produced. Lower fluences limited side effects to hyperpigmentaion, erythema and rarely blisters. Another advantage of the excimer laser is that the dosage can be adjusted to specific lesions, unlike in conventional laser therapy. However, excimer laser is effective only in localized psoriasis. Therefore, the current view is that the excimer laser therapy should be seen as a complement, rather than as a competitor, to conventional therapy.

Vitiligo treatment

Vitiligo treatments can be mono or combined therapies.

The excimer laser, at low fluences, gives very good results with good patience tolerance in localized vitiligo. The immediate side effects were erythema and rare blister lesions. In some cases depigmentation occurred, three years after treatment.

Studies have shown the combined therapy of excimer laser and topical 0.1% tacrrolimus as superior to monotherapy in terms of efficacy and short response time. However, sample sizes were small in these studies. Further action needs confirmation from studies on larger populations. Another reason for holding back the use of this combined therapy is the uncertainty about the risk of cancer posed by the use of tacrrolimus.

Acne laser treatment

Laser treatment of acne is now an established therapy. With its direct action on the sebaceous glands, it gives superior results. It has to a great extent overcome the drawbacks of traditional therapies. Many kinds of lasers giving variable results are now in use.

The 1450nm diode laser and PDT give the best results. Better results are obtained when laser treatment is combined with other therapies. The latest PDT has also been used successfully.

Lasers may be the preferred option in cases where the patient cannot or does not want to use topical or systemic treatments. However, laser treatment is an expensive option. Multiple sessions are often needed. Side effects include pain and skin discoloration.

Laser treatments for other skin lesions

Other skin lesions, such as, warts, nevi, rhinophyma, seborrheic keratoses and ulcers are some of the vast number of skin lesions, where laser treatment is a viable option. In the majority of cases, the new high-powered short-pulsed CO2 lasers are used.

In refractory warts, the newer PDL has replaced CO2 laser as the treatmen of choice. For rhinophyma, CO2 laser with anesthesia gives precise tissue removal. For severe rhiniphyma, prior excision may be necessary before laser treatment.

Epidermal nevi therapy was difficult tom treat before the advent of CO2 lasers. Surgery was difficult due to the size and configuration of the lesions and left ugly scars. The ultra-pulsed CO2 laser gives, arguably, the best results.

CO2 lasers have been very effective in clearing thick and large seborrheic keratoses though there is some scarring. Scarring is much less with ultra-pulsed lasers.

Studies have shown that ulcers can be successfully treated by CO2 and Nd:YAG lasers. These treatments improve the healing process.

Conclusions

Laser treatments of various skin lesions have given variable results. However, on an average, lasers have brought about significant imrovements in treatment outcomes. The future holds promise of even better laser therapies.