PDL a mainstay in management of hypertrophic scars, keloids

Washington - Irradiation with the 585-nm flashlamp pulsed dye laser (PDL) has emerged as a treatment of choice for hypertrophic scars and keloids, but it is important to distinguish between those two types of lesions since the approach to their management differs, Elizabeth L. Tanzi, M.D. says.

"Used by itself, the pulsed dye laser can be highly effective in improving hypertrophic scars, whereas a combination technique using the laser and intralesional injections is often necessary to achieve a desirable response for keloids," notes Dr. Tanzi, co-director of laser surgery, Washington Institute of Dermatologic Laser Surgery, Washington, D.C.

Based on various studies using a variety of outcome measures, the PDL is now considered a first-line option for treating hypertrophic scars.

The results of those investigations show that benefits, including improvements in pliability, erythema, fibrosis and pruritus, can be achieved with treatment that is well-tolerated and associated with minimal risks. However, the key to a successful outcome is to use low-to-moderate fluences administered in multiple sessions, Dr. Tanzi says.

"Previous PDL treatment with higher energies is a common underlying theme for patients who have been referred to our center after having failed laser treatment elsewhere. These scars need to be treated with respect, and that means being conservative with multiple treatments and lower energies," she explains.

Initiation

Preferably, PDL treatment should be initiated within the first two to four weeks after scar development. The entire surface of the scar is treated with non-overlapping, adjacent pulses using a 10 mm spot size, 5 J/cm² fluence, and a 1.5 msec pulse duration. The fluence may be reduced even lower if treating scars located in anatomic areas where the skin is especially sensitive, such as under the eyes, on the neck, and on the chest, or in patients with darker skin phototypes who are particularly prone to develop hyperpigmentation.

Following PDL treatment, edema may be present for up to 48 hours and purpura may persist for several days, but both are self-limiting. Importantly, patients should be instructed about strict sun avoidance in order to prevent stimulation of excessive pigment production.

"Epidermal melanin may interfere with absorption of laser energy by the intended target, and if hyperpigmentation develops, its resolution can be enhanced with the use of topical bleaching agents. However, retreatment with the PDL should be delayed until excess pigment has disappeared," Dr. Tanzi says.

Treatment administration

Up to three or four PDL treatments administered at six-week intervals are usually performed to achieve optimal improvement of hypertrophic scars.

It is the exceptional case, usually one that is highly symptomatic, that may be treated adjunctively with intralesional injection of triamcinolone or 5-fluorouracil. In fact, results of a split scar study undertaken by Tina S. Alster, M.D., director, Washington Institute of Dermatologic Laser Surgery, showed the addition of intralesional steroid treatment to irradiation with the PDL had no benefit for enhancing improvements achieved in hypertrophic inframammary scars, Dr. Tanzi tells Dermatology Times.

In contrast, a combination laser-medical regimen is used routinely for treating keloids.

"Keloids are much thicker, more fibrotic, and more active than hypertrophic scars, and better results are achieved with a dual regimen," Dr. Tanzi says.

In treating keloids, the two interventions are usually administered at the same visit, with the laser treatment performed first followed immediately by the intralesional injection. The laser settings are the same as those used in treating hypertrophic scars, and repeat treatments are also performed at six-week intervals.