BALTIMORE — Laser treatment for solar lentigines in individuals with darker skin types has long been associated with a higher risk of postinflammatory hyperpigmentation (PIH), but.
The study enrolled 27 patients with solar lentigines and Fitzpatrick skin types (FSTs) III-IV, Woraphong Manuskiatti, MD, professor of dermatology at Siriraj Hospital, Mahidol University, Bangkok, reported at the annual meeting of the American Society for Laser Medicine and Surgery. They received the fractional beam treatment on one side of the face and the full-beam on the other side. At 6 months, the incidence of PIH was about 81% lower on the fractional-beam side, Dr. Manuskiatti said.
“In the past, when we used laser to treat pigmented lesions, we used the so-called full-beam technique on the pigmented area,” Dr. Manuskiatti told this news organization. “From the study, we found that you don’t need to treat it at 100%. You can fractionally treat the pigmented lesion and get a really comparable treatment outcome and, at that reduced beam, less incidence of postinflammatory hyperpigmentation.”
Study Design and Results
Of the 27 patients in the study, 12 were FST III (44%), 14 were FST IV (52%), and one was FST V (4%). On the fractional-beam side, the laser was delivered through a 9-mm spot size with an average fluence of 0.47 J/cm² at a frequency of 2 Hz for a total of two passes without pulse overlapping. On the full-beam side, the laser was operated with a 4.5-mm handpiece, with fluence ranging from 0.3 to 0.7 J/cm² (using an endpoint of slight darkening of the pigmented lesion) at 2 Hz.
The patients received a single treatment and had a clinical evaluation and color reading assessments at 2 weeks, 1 month, 3 months, and 6 months after the treatment. Twenty-five patients completed the study.
The researchers found no statistically significant differences in lesional clearance between the two techniques at any of the follow-up assessments, Dr. Manuskiatti said. “This might be one of the alternative treatments of treating solar lentigines in dark-skinned patients,” he said when presenting the study results.
He reported the rates of PIH on the full-beam and fractional-beam sides, respectively, at the following intervals were: 64% and 8% at 2 weeks, 80% and 32% at 1 month, 96% and 36% at 3 months, and 88% and 16% at 6 months.
“The incidence of PIH on the full-beam side was statistically higher than that on the fractional-beam side throughout the follow-up period,” he said. Transient and mild hypopigmentation was observed in one patient (4%) on the fractional-beam side and in five (20%) on the full-beam side. Dr. Manuskiatti added that no other adverse effects were documented during the study.
“ Normally when you use laser to treat skin type I or II, you don’t have … PIH or darkening of the skin,” Dr. Manuskiatti told this news organization, “but when you have skin type III and above, you run into a really high incidence of postinflammatory hyperpigmentation — and treating that with fractional beam can lead to a reduced incidence of darkening of the skin afterward.”