Large-Spot, Variable-Pulsed KTP Laser Demonstrates Safety and Efficacy in Port-Wine Birthmarks

A recent study reported that large-spot, variable-sequenced, long-pulsed potassium titanyl phosphate (KTP) laser led to safe, effective, and significant lightening of lesions and surface area reduction in patients with port-wine birthmarks (PWBs).¹

The study, published in the Journal of Cosmetic Dermatology, noted that KTP lasers may serve as a complementary or alternative modality to the PWB treatment gold standard, pulsed-dye lasers (PDLs).

Port wine stain | Image Credit: © Te Whatu Ora Health New Zealand, DermNet

Background and Methods

Earlier studies by members of the current research team reported similar findings, laying the groundwork for the present investigation.

Their 2024 study, published in the Journal of the European Academy of Dermatology and Venereology, compared PDLs with KTPs in a prospective, randomized, split-side manner.² Both treatments demonstrated similar efficacy and high patient satisfaction in cases of PWBs. However, use of the KTP laser lead to fewer post-treatment reactions and had no equipment malfunctions, whereas the PDL system experienced over 6 months of downtime.

Despite the success observed in this prior study, as well as studies exploring the use of KTP lasers in other indications such as rosacea,³ researchers sought to examine the efficacy of KTPs over a longer duration of time.

The study was conducted between 2021 and 2024 at a single academic center. Efficacy was evaluated through standardized 3D imaging, colorimetric analysis, and lesion size measurements, while safety and adverse events were documented through clinical records and photo documentation.

Findings

A total of 69 patients with PWBs were included in the analysis, with a mean age of 36.5 years. Just under 60% of participants were female, and the majority had Fitzpatrick skin type II. Most PWBs (82.6%) were facial, with baseline lesion sizes averaging nearly 29 cm². Notably, over 85% of patients had received prior treatment, primarily with PDLs, averaging more than 6 sessions.

In the current study, patients underwent a mean of 5.6 KTP laser treatments using a large-spot, variable-pulse 532 nm system.

Colorimetric analysis demonstrated significant improvement in erythema. The ΔE value, representing color difference between lesional and surrounding skin, decreased from 19.9 at baseline to 14.1 post-treatment (p < 0.05), indicating measurable clearance. This reduction in erythema translated to an average improvement of 75.7%. Visual documentation supported these findings, with before-and-after images showing notable blanching of the lesions after multiple sessions, even in patients who had limited response to prior therapies.

The average surface area of treated PWBs also declined significantly, shrinking from 28.1 cm² to 22.7 cm², reflecting a 25.3% reduction (p < 0.05).

The KTP laser was well tolerated overall: all patients experienced transient erythema and mild swelling, while a small number developed crusting or more pronounced swelling that resolved without long-term effects. No cases of blistering, scarring, or postinflammatory hyperpigmentation were reported.

Conclusions

The study may have been limited by its retrospective design, the absence of a control arm, and a predominance of patients with Fitzpatrick skin type II included in the study.

"This study is the first to examine the potential of a large-spot, variable-sequenced, long-pulsed KTP for achieving lesion clearance and evaluating safety in the treatment of PWBs over a period of more than 3 years," wrote authors Nguyen et al. "Our findings revealed significant lightening of PWBs based on objective colorimetric analysis, alongside a notable decrease in size."

Moving forward, researchers noted that additional studies are warranted, primarily in an effort to determine optimal laser settings and parameters for personalized treatment approaches.

References

1. Nguyen L, Schneider SW, Herberger K. Treatment of port-wine birthmarks using a large-spot, variable sequenced, long-pulsed KTP-laser-a retrospective analysis. J Cosmet Dermatol. 2025;24(4):e70152. doi:10.1111/jocd.70152
2. Nguyen L, Seeber N, Kautz G, Hartjen A, Schneider SW, Herberger K. 532-nm potassium titanyl-phosphate laser versus 595-nm pulsed dye laser for port-wine birthmarks: A prospective, randomized, split-side study. J Eur Acad Dermatol Venereol. 2024;38(6):1140-1146. doi:10.1111/jdv.19750
3. Nguyen L, Dierckxsens C, Kerscher M, Hartjen A, Schneider SW, Herberger K. Rosacea treatment with 532 nm KTP versus 595 nm pulsed dye laser-A prospective, controlled study. J Cosmet Dermatol. 2024;23(7):2443-2449. doi:10.1111/jocd.16300