ADVANCES IN DERMATOLOGIC SURGERY - Editors: Jeffrey S. Dover, MD and Murad Alam, MD

The Use of Lasers in the Pediatric Population

K. Mariwalla, MD¹, J. S. Dover, MD, FRCPC<sup>2-4

1</sup>Department of Medicine, Massachusetts General Hospital, Boston, MA, USA
²Department of Dermatology, Yale University School of Medicine, New Haven, CT, USA
³SkinCare Physicians of Chestnut Hill, Chestnut Hill, MA, USA
⁴Department of Medicine (Dermatology), Dartmouth Medical School, Hanover, NH, USA

ABSTRACT

Over the past 2 decades, there have been numerous advances in laser therapy of birthmarks in the pediatric population. Concerns regarding efficacy, overall benefit, and side-effects linger. We present our opinion, based upon decades of clinical experience, on the role of lasers to treat port wine stains, superficial hemangiomas, and café au lait macules in children.

Key Words: hemangioma, café au lait macules, pediatrics

Port Wine Stains

Port wine stains (PWSs) are congenital vascular malformations composed of ectatic capillary-like vessels in the papillary dermis that occur in 0.3% of newborns. They can vary in size (millimeters to >50% body surface area) and color (flat pink patches to “cobblestoned” purple plaques) as the patient ages. Children with PWSs should be treated early to prevent adverse sequelae to their psychological development.

Observable reduction in PWS size and color is achieved through laser therapy by selective vascular damage. The pulsed dye laser (PDL) is the laser of choice due to its low risk of scarring or pigmentary alteration^1,2 and relatively high rates of clearing.

Which Laser Is Best for Children?

In one study, use of the 595nm PDL with 1.5msec pulse width and fluences up to 11-12J/cm2 with a dynamic cooling spray resulted in >75% clearance of PWSs in 63% of patients under the age of 12 months, after four treatments.³ Lack of controlled trials with single parameter variation make it difficult to ascertain optimal settings in this area. The addition of a dynamic cryogen cooling device (DCD) has advanced the treatment of PWSs by allowing for epidermal protection via surface cooling and resultant heat accumulation in vessels. Recently Bernstein and Brown, using the 585nm PDL with DCD at a 1.5msec pulse duration, demonstrated an average 68% subjective and 69% objective improvement in 83 previously untreated PWSs after approximately four treatments.⁴ Additional devices, including the 1064nm Nd:YAG are now also being tested for PWS combination treatment.⁵

We routinely start with the largest available spot size (10mm), a pulse duration of 1.5msec, and fluence of 7.5J/cm2 with the V-Beam laser (Candela) and then, depending on the outcome, we may reduce the spot size to 7.0mm and vary the fluence from 9-14J/cm2 or 6-8.5J/cm2 with the V-Star laser (Cynosure). Treated tissue should appear dark purple but not assume a grayish hue, which may indicate potential overtreatment. This temporary purpura may last 7-10 days.

Will It Work?

Certain favorable prognostic features are known about PWSs. We advocate early treatment; success is likely due to thinner skin in infants, as well as smaller and more superficial vessels leading to improved clearance in fewer treatment sessions.⁶ Based on current studies, >50% improvement has been reported after an average of four treatments per patient.^3,4,7

Pearls	Pitfalls
Mark treatment site because reactive erythema often clouds otherwise distinct borders. Treat edge of PWS first to prevent inadvertent treatment of unaffected adjacent skin. Aim the laser tangentially to the skin surface when treating central areas to avoid the uneven, lattice-like appearance of partially treated areas.8 For darker skin types, waiting as long as 3 months between treatment sessions is recommended to permit postinflammatory hyperpigmentation, if present, to resolve.	The risk of hypertrophic and atrophic scarring exists but is extraordinarily low. Cutaneous atrophy that may rarely appear within 1-2 months following PDL treatment usually resolves within a 3- to 18-month period. In dark-skinned individuals, epidermal sloughing can develop following treatment, requiring wound care and leading to pigmentary change. Clearance is location dependent (see next page).
Table 1: Use of the PDL to treat port wine stains

Red lesions appear to clear more with the PDL than pink or purple lesions and lesions on the head and neck respond more favorably than those on the trunk and lower extremities. Furthermore, the midline facial area responds better than the lateral face and neck.

PWSs rarely clear completely even with a series of treatments, but optimal improvement is usually achieved with repeat sessions every 4-8 weeks. PWSs may respond, (to a lesser degree) in skin types IV and V with lower fluences and multiple treatments, though the risk of pigmentary alteration is more common than that in lighter skin tones (see Table 1).

Superficial Hemangiomas

Superficial hemangiomas are benign proliferations of endothelial tissue with an incidence of almost 10% by the age of 1 year. They are frequently located on the head or neck and if not present at birth, usually appear shortly thereafter, showing a female-to-male predominance. The natural history of these hemangiomas has two phases, proliferating (marked by significant growth during the first 7 months of life) and involuting (pallor within the lesion followed by involution and residual atrophic telangiectatic skin with fibrofatty tissue in some cases). Complications such as ulceration, obstruction of vital structures, and recurrent bleeding can occur. Laser therapy can prevent such complications and provide psychological relief for pediatric patients and their parents during the first few years of life. Early treatment reduces the chance that the lesion will reach its full size and minimizes the risk of fibrofatty tissue development. Which Laser Is Best for Children? The short-pulsed (0.45-1.5msec) PDL (either 585nm or 595nm) with dynamic or air cooling is the treatment of choice for hemangiomas comprised mostly of superficial vessels.⁹ Since the depth of selective photothermolysis with the 585nm PDL is 1.2mm, deeper components of hemangiomas may progress. Better results are often achieved with larger spot sizes (7mm, 10mm).10 Newer long-pulsed Nd:YAG lasers may be more effective but further study is necessary.

Will It Work?

Although opinions differ regarding the treatment of hemangiomas in patients younger than 4 months old¹¹ (as hemangiomas may spontaneously resolve within the first year of life), long-term studies have not been carried out using objective observers nor have data regarding significant improvement vs. clearance been reported. We advocate early intervention given the minimal risks associated with laser therapy and the notion that the most effective time for treatment is during the proliferation phase. Some evidence suggests lesions less than 3mm may resolve better than thicker lesions.¹² As in treatment of PWSs, the basic principles of depth and size apply to efficacy of laser therapy. Multiple treatments may be needed to achieve maximal clearing and are recommended to begin during the rapid proliferating phase in 2-3 week intervals. During the involuting phase, treatments can be spread out to every 1-2 months.

Ulceration and subsequent pain is a frequent complication in 5%-14% of all infantile hemangiomas and though compelling data do not exist to support the use of a single therapy,¹³ faster rates of resolution may occur with the PDL^14,15 than with Nd:YAG lasers, potentially due to increasing rates of reepithelialization. In our practice, we always start with biologic dressings and add PDL if this fails.

Café au Lait Macules

Café au lait macules (CALMs) are benign hyperpigmented areas, present at birth in 2% of all newborns (up to 1/3 of black neonates).¹⁶ While they can be markers for underlying disease such as neurofibromatosis, isolated CALMs are recognized as a common finding in many infants and may increase in size over time. The exact etiology of the macules is unknown. Cosmetic improvement can be achieved by use of any of the short-pulsed lasers which selectively destroy melanosomes.

Which Laser Is Best for Children?

Laser therapy for CALMs is considered safe but there is no data to suggest that treatment of CALMs in infancy is required. The best choice is the Q-switched pigment-specific laser. Efficacy studies on the Q-switched Nd:YAG lasers (532nm or 1064nm), the Q-switched alexandrite (755nm), and the Q-switched ruby laser (694nm) show that each of these lasers works with varying degrees of efficacy;¹⁷ to date no study comparing the Q-switched lasers has been carried out. Wheeland and Schmults¹⁸ recommend the Q-switched 532nm Nd:YAG laser, though it is worth mentioning that the risk of purpura and postoperative abradement of the treated area may be unacceptable to parents of pediatric patients.

Pearls	Pitfalls
Best for non-tan skin phototypes I – III. Topical or intradermal local anesthetics are often required. All children and their parents should be given laser-specific optically coated glasses. Always determine treatment parameters with a test spot, which should be evaluated after 4-8 weeks. Begin with the lowest energy fluence that produces a visible response. Do not overlap areas.	Hyperpigmentation can occur, but usually improves with the passage of time or the application of topical bleaching creams. Risk of hypopigmentation is higher with the Q-switched ruby laser than for the Q-switched alexandrite and the Qswitched Nd:YAG at 1064.19 The area may appear abraded after treatment. Wound care should be started and continued until the area is completely reepithelialized. Treatment area should heal within 5-14 days.
Table 1: Use of Q-switched lasers to treat café au lait macules

Will It Work?

Clinical experience with repeated Q-switched laser treatments has been inconsistent, with total clearing occurring in approximately 50% of patients and recurrence and patchy pigmentation occurring in the other half.¹⁹ The risk of repigmentation exists for all CALMs though the mechanism behind this is unknown. It appears that if total clearing is achieved repigmentation is rare, though an exact percentage has not been uniformly reported. The key to successful treatment is to use relatively low fluences and perform multiple treatment sessions 6-8 weeks apart. It is generally agreed that results seen at 12 months after the last treatment are usually lasting.^20,21 Given the risk of pigmentary alteration, skin types IV-VI should generally not be treated, as CALMs are often less apparent and the risk of pigment change outweighs cosmesis. In all skin types, the risk of postinflammatory hypopigmentation exists, and if this occurs, a delay in further treatments until the pigmentation normalizes is recommended (see Table 2).

Conclusion

While additional long-term studies may be needed to assess the efficacy of laser therapy in the pediatric population, our experience suggests that laser use in children for the treatment of port wine stains, superficial hemangiomas, and café au lait macules has not only been well tolerated by patients but also successful with minimal side-effects.

References

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16. Chang MW, Levine N, Trout C. Disorders of hyperpigmentation. In: Bolognia JL, Jorizzo JL, Rapini RP, editors. Dermatology. Volume 1. Spain: Mosby p975-1004 (2003).
17. Grossman MC, Anderson RR, Farinelli W, Flotte TJ, Grevelink JM. Treatment of café au lait macules with lasers. A clinicopathologic correlation. Arch Dermatol 131(12):1416-20 (1995 Dec).
18. Wheeland R, Schmults C. Pigmented lesions and tattoos. In: Dover JS, Goldberg DJ, editors. Procedures in Cosmetic Dermatology, Laser and Lights. Volume 1. China: Elsevier Saunders p41-66 (2005).
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20. Alster RS. Complete elimination of large café au lait birthmarks by the 510 nm pulsed dye laser. Plast Reconstr Surg 96:1660-4 (1995).
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