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Pulsed dye laser (PDL) treatment is based on the principle of selective photothermolysis and is widely considered to be the treatment of choice for a variety of cutaneous vascular lesions.
Objective
To review the indications and outcome of PDL treatment and summarise new developments.
Method
A literature-based study has been conducted entailing the review of publications over the period January 1993–December 2003 using the databases Medline and Cochrane CENTRAL.
Results
The PDL was found to be effective in port wine stain, facial telangiectasia, leg telangiectasia <0.5 mm, scars, hypertrophic scars and ulcerated haemangioma.
Discussion
Essential characteristics of lesions suitable for PDL treatment are discussed and guidelines are presented for future research.
SPT is a process of selective damage to chromophores by monochrome light. Three basic conditions are necessary to achieve SPT: (1) a wavelength that is preferentially absorbed by the targeted structure, (2) an exposure duration less than or equal to the thermal relaxation time of the target, (3) sufficient radiant exposure (fluence; delivered energy per unit area) to reach damaging temperatures in the targeted structure.
The parameters of the PDL are chosen so, that the light is well absorbed by oxyhaemoglobin and the pulse duration is suitable for small vessels in the skin. Initially, the wavelength of the PDL was 577 nm and the pulse duration 0.3 ms. To achieve a greater depth of penetration with a similar vascular selectivity, this was modified to a pulse duration of 0.45 ms and a wavelength of 585 nm, in the late eighties.
Most commonly used fluences range between 5 and 8 J/cm2.
Side-effects and complications
Purpura is the most apparent side-effect of PDL treatment, arising during treatment and remaining clinically apparent for 2–14 days. Complications can occur. Even after a successful test-treatment Woltzke et al.
observed crusting in 25% and bleeding in 12% of the cases. His most common long-term complication was hyperpigmentation (27%), followed by atrophic scarring (3%), hypopigmentation (1%) and hypertrophic scarring (1%). However, most of these changes were only focal and predominantly transient.
A darker skin increases the risk of complications and decreases the depth of penetration, because the energy of the PDL is absorbed by melanin. Patients with a darker skin (Fitzpatrick V) should, however, not be excluded from treatment, provided that treatment expectations and risks are fully appreciated (Table 1).
A literature-based study has been conducted entailing the review of publications over the period January 1993–December 2003 using the databases Medline and Cochrane CENTRAL. The following search terms have been used: ‘dye near laser’ in combination with ‘port wine stain*’ or vascular ‘malfomation’, ‘telangiectasi*’, ‘scar*’ and ‘haemangiom*’ or ‘haemangiom*’, combined with these inclusion criteria: only publications in the English language, trials with a population of at least 10. Furthermore, for haemangioma and vascular malformations, trials had to satisfy the classification of Mulliken. Case reports and reviews were excluded.
Results
The search resulted in 71 hits on port wine stain (PWS), 24 on telangiectasia, 19 on scars and nine on haemagioma. Of the 123 trials reviewed, 63% were prospective, 34% were based on objective measurements and 24% were controlled. Per lesion the percentages of trials done prospectively, objectively or controlled quite differ, as shown in Table 2.
PWS or capillary malformations, are by definition present at birth. The skin discolouration is usually, but not always evident at birth. These malformations are characterised by a normal endothelial micro-architecture. They are structural abnormalities caused by a developmental disorder of the capillary vessels during the post-zygotic stage. Involution does not occur.
Photothermally induced vessel-wall necrosis after pulsed dye laser treatment: lack of response in port-wine stains with small sized or deeply located vessels.
Unfortunately, there are no methods to investigate both the depth and vessel diameter of the PWS. Using ultrasound it is only possible to investigate the depth of the lesion.
Changes in skin redness, pigmentation, echostructure, thickness, and surface contour after 1 pulsed dye laser treatment of port-wine stains in children.
Photothermally induced vessel-wall necrosis after pulsed dye laser treatment: lack of response in port-wine stains with small sized or deeply located vessels.
However, this is an invasive procedure and may not be predictive for the entire lesion. Otherwise, it is possible to predict the clearing by measuring the colour of the PWS in an objective way before every treatment, for example with a colorimeter. Because an equal percentage of clearing per treatment can be expected, it is possible to predict the result after a number of treatments.
(Fig. 1). The location of the PWS is of predictive value for treatment outcome. Lesions on the forehead, lateral face, neck and trunk respond more favourably than lesions located on the central face, lip, chin, dermatome V2 of the face and extremities.
Although complete clearance is hardly ever achieved, most patients are satisfied with the treatment outcome. They report improvements in terms of self-esteem, contact with the opposite sex and making new acquaintances. In addition, they are more assertive, cover their PWS less, experience less negative reactions from peers.
Telangiectasia consists of dilated capillaries that appear clinically as tiny erythematous to violaceous cutaneous vessels. These may blanche, but do not tend to fade with time.
A spider nevus is a localised network of dilated capillaries radiating from a central ‘feeding’ arteriole. They can fade spontaneously, but more commonly they persist.
Spider nevi with an elevated central point require a higher fleunce, more treatments and can return after a while (10% recurrence within a period of 6 months).
Leg telangiectasia differ from facial telangiectasia. Generally their diameter is larger, their haemoglobin is not fully saturated and the blood content of the surrounding dermis is different.
This is why the long pulsed dye laser (LPDL) is used on leg telangiectasia. The LPDL has a greater penetration depth and causes more selective thermal damage to larger vessels. Clinically, the LPDL is most effective in the treatment of leg telangiectasia with a diameter up to 0.5 mm.
Sclerotherapy remains the treatment of choice for leg telangiectasia in which the LPDL can have an additional role in treating small, superficial vessels.
PDL treatment on the suture removal day results in an improvement in vascularity and pliability after 4 months. In addition, biopsies reveal more superficial dermis elastin production and less unidirectional collagen in clusters, which is consistent with clinical and histologic fibrosis.
Hypertrophic scars are defined as raised, erythematous, and often pruritic scars. They remain within the boundaries of the original wound. Scar formation usually begins within 6–8 weeks from injury and can worsen for up to 6 months. The maturation phase may last 1–2 years and the scars may regress without intervention. The extent of scarring is related to the depth and area of the original injury.
Prospective, single-blind, randomized, controlled study to assess the efficacy of the 585-nm flashlamp-pumped pulsed-dye laser and silicone gel sheeting in hypertrophic scar treatment.
Treatment response of keloidal and hypertrophic sternotomy scars: comparison among intralesional corticosteroid, 5-fluorouracil, and 585-nm flashlamp-pumped pulsed-dye laser treatments.
only demonstrated significant improvement in terms of pruritus.
Haemangioma
Haemangiomas are benign endothelial tumours; in 30% of the cases they are visible at birth as small macula. At the end of the 1st year life stabilisation in growth will occur in most cases. This is followed by involution. All haemangiomata eventually involute. However, residual impairments such as atrophic scarring, pigmentation imperfection or fibrofatty tissue surplus are possible.
(involving 121 infants aged 1–14 weeks with early haemangiomas) showed that the percentage of completely cleared haemangiomas was significantly higher in the group treated with PDL after an 1 year follow-up. However, when looked at in terms of complete clearance or minimal residual signs, there was no significant difference between the treated and untreated group. Along with the time and costs and chance of complications the authors advise against treating uncomplicated haemangiomas with the PDL.
This is different in the case of ulcerated haemangiomas. Trials involving ulcerated haemangiomas
Although PDL is effective in the treatment of ulcerated haemangiomas, there are other treatment options such as topical antibiotics and steroids. It is best to determine the way of treatment by the characteristics of the specific lesion and its reaction to the chosen therapy.
Deeply located haemangiomas do not benefit from PDL treatment. An explanation for this is the minimal depth of penetration (1–2 mm) of the PDL.
Before treating vascular malformations it is import to consider if there is any underlying pathology. Vascular malformations, like PWS and telangiectasia, may be sporadically associated with several syndromes such as Klippel–Trenaunay syndrome and Sturge–Weber syndrome.
Histologic evaluation of skin damage after overlapping and nonoverlapping flashlamp pumped pulsed dye laser pulses: a study on normal human skin as a model for port wine stains.
In case of telangiectasia it is advisable to use an elliptic spot.
During treatment, it is customary to cool the dermis. Initially this was done with ice. Currently cryogen spray and cold air are the preferred cooling methods. Cooling has two advantages.
Firstly, there is an analgesic effect. Secondly, by cooling, the surrounding dermis is protected from thermal damage, which allows higher fluences to be used without increasing the chance of complications.
For recommendations for use per type of lesion, based on a literature summary, see Table 3. When using different brands of PDL with supposedly equivalent fluences, one cannot guarantee that clinical results will be equivalent.
Treatment response of keloidal and hypertrophic sternotomy scars: comparison among intralesional corticosteroid, 5-fluorouracil, and 585-nm flashlamp-pumped pulsed-dye laser treatments.
Prospective, single-blind, randomized, controlled study to assess the efficacy of the 585-nm flashlamp-pumped pulsed-dye laser and silicone gel sheeting in hypertrophic scar treatment.
Treatment response of keloidal and hypertrophic sternotomy scars: comparison among intralesional corticosteroid, 5-fluorouracil, and 585-nm flashlamp-pumped pulsed-dye laser treatments.
Of the 123 trials found 44 were used in the review. The trials were selected per subject. Controlled, prospective, larger trials that were based on objective measurements were preferred over those that were not. Trials like those of Batta et al.,
Treatment response of keloidal and hypertrophic sternotomy scars: comparison among intralesional corticosteroid, 5-fluorouracil, and 585-nm flashlamp-pumped pulsed-dye laser treatments.
are leading trials on these points. These trials have set new and rational standards for PDL treatment and research for haemangiomas, vascular malformations and hypertrophic scars. The trial of van-der-Horst et al.
were able to prove the inefficacy of PDL treatment in uncomplicated haemangiomas, contradicting other trials that were done less meticulously.
Manipulation of the characteristics of vascular lesions to make them more susceptible to PDL treatment, is a promising research field. An example is the trial of Svaasand et al.,
in which the lumen of PWS vessels was increased by applying pressure proximal of the PWS. In doing so, a significant reduction in ‘small-vessel-limitation’ was achieved. Other possible adjustments are reducing the diameter of leg telangiectasia and adjusting the vessel diameter of PWS vessels in other ways, for example with local vasodilators. Methods that have a prognostic value in PDL treatment should also be further explored. At present, main methods are the echo-Doppler, biopsy and colorimeter. These techniques are either incomplete, invasive or depend on extrapolation of treatment results. They cannot accurately predict the reaction of the lesion prior to treatment. The introduction of a method that can predict the outcome of the PDL treatment prior to treatment will be valuable for both patients and doctors. Technical developments might, however, be a limiting factor to create such a method at the moment.
When comparing trials on hypertrophic scars, results show that treatment interval may influence the outcome.
Prospective, single-blind, randomized, controlled study to assess the efficacy of the 585-nm flashlamp-pumped pulsed-dye laser and silicone gel sheeting in hypertrophic scar treatment.
Treatment response of keloidal and hypertrophic sternotomy scars: comparison among intralesional corticosteroid, 5-fluorouracil, and 585-nm flashlamp-pumped pulsed-dye laser treatments.
Treatment response of keloidal and hypertrophic sternotomy scars: comparison among intralesional corticosteroid, 5-fluorouracil, and 585-nm flashlamp-pumped pulsed-dye laser treatments.
Future research will need to address these issues.
Apart from research on hypertrophic scars the long-term results of PDL treatment on ‘fresh’ scars needs to be investigated. Although short-term results are positive,
Because of its success in treating superficial lesions with small caliber vessels, the PDL is also being used for other red lesions. Although these lesions are red, they do not always match the PDL-characteristics of 1.5 mm penetration depth
Histologic evaluation of skin damage after overlapping and nonoverlapping flashlamp pumped pulsed dye laser pulses: a study on normal human skin as a model for port wine stains.
In these cases, PDL treatment might not be the best therapeutic option and the patient might be better of with an other kind of treatment or even no treatment at all. To prevent useless treatment it is important always to consider the characteristics of the lesion before treatment. If the lesion characteristics and the PDL parameters match it will be a good therapeutic option.
Acknowledgements
The authors thank Dr P. Koster for the critical reading of the manuscript.
References
Alster T.
Laser scar revision: comparison study of 585-nm pulsed dye laser with and without intralesional corticosteroids.
Photothermally induced vessel-wall necrosis after pulsed dye laser treatment: lack of response in port-wine stains with small sized or deeply located vessels.
Changes in skin redness, pigmentation, echostructure, thickness, and surface contour after 1 pulsed dye laser treatment of port-wine stains in children.
Prospective, single-blind, randomized, controlled study to assess the efficacy of the 585-nm flashlamp-pumped pulsed-dye laser and silicone gel sheeting in hypertrophic scar treatment.
Treatment response of keloidal and hypertrophic sternotomy scars: comparison among intralesional corticosteroid, 5-fluorouracil, and 585-nm flashlamp-pumped pulsed-dye laser treatments.
Histologic evaluation of skin damage after overlapping and nonoverlapping flashlamp pumped pulsed dye laser pulses: a study on normal human skin as a model for port wine stains.
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