Long‐term follow‐up outcomes of laser‐treated port wine stain patients: A double‐blinded retrospective study

Port wine stains (PWS) can be effectively treated with lasers. However, complete clearance is rarely observed, and data from long‐term studies are limited. The study aimed to evaluate the efficacy and complications of long‐term laser treatment in patients with PWS.

treatment modalities, including various lasers, have been used to improve therapeutic outcomes. However, few studies have reported excellent results. 5 Due to a lack of long-term follow-up studies, here we performed a 25-year double-blinded retrospective chart review to study the long-term outcomes of patients with PWS.

| Patients
This study included patients diagnosed with PWS who underwent laser treatment at Ramathibodi Hospital between June 1995 and June 2021. Photographic records before and after treatment were also collected. Patients for whom data, photographic records, or other dermatological conditions of the lesions were missing were excluded.

| Data extraction and collection
Demographic data, including sex, age, Fitzpatrick skin type, diagnostic date, treatment start date, treatment end date, treatment duration, number of treatments, follow-up interval, characteristics of PWS (site, number of lesions, hypertrophy, and mucosal involvement), associated conditions, laser treatment type, and posttreatment complications were recorded. Facial PWS distribution was documented based on the embryonic facial vasculature. 2 Each laser treatment session was recorded for each patient, as some received more than one type of laser treatment.

F I G U R E 2
The improvement in PWS lesions after multiple laser treatment sessions compared to pretreatment. The pretreatment lesion was identified as NRS 0 (no improvement) (A) and posttreatment lesion was identified as NRS 4 (76%-99% improvement) (B).

| Statistical analysis
Categorical data are presented as frequency (percentage). Normally

| RE SULTS
A total of 306 patients met the inclusion criteria. After the exclusion of 177 patients for whom data were missing, 129 were included in this study. A total of 4141 laser treatment sessions were conducted.
Some patients underwent more than one type of laser treatment.
All 1070 of their photographic records were evaluated in this study.
The demographic data of all patients and laser treatments are shown in Table 1. The majority of patients were male (70.54%).     Complications are shown in Table 3. The most common complication was purpura (25.54%), followed by hyperpigmentation (17.50%), and blebbing (13.77%). Abbreviations: IQR, interquartile range; PWS, port wine stain.

TA B L E 2
Factors associated with good versus poor improvement.

F I G U R E 3
A significant correlation between the number of treatment sessions and improvement score (50%) was first seen after six treatment sessions.
10-year follow-up after PDL therapy. 10 According to the hypoth- such as long-pulse alexandrite or long-pulse Nd:YAG, which provide greater penetration depth, may have a role in treating these lesions. However, these lasers carry a higher risk of causing scars and pigmentation, which can lead to unfavorable outcomes. 12,13 In terms of distribution, many studies have reported that the centrofacial area and S2 are associated with poor outcomes. 14 Here we observed that lesions on the upper eyelid and nasal tip were associated with poor outcomes. We hypothesized that the upper eyelid is a vulnerable area where patients tend to avoid surgery. Regarding poor nasal tip outcomes, laser probe placement can be challenging owing to its curvature. As mentioned previously, better outcomes can be observed with a greater number of treatments. The treatment follow-up duration should be within 6 months, and we found that a treatment follow-up longer than 6 months was associated with poor outcomes.
Laser treatments are more effective in children than in adults.
Aggressive treatment in young children can improve PWS clearance because of their thinner skin and smaller lesion size. 15,16 Furthermore, treatment delays can result in resistant PWS, which eventually progresses to nodularity, leading to difficult-to-treat lesions in adulthood. 17 However, we did not observe a correlation between early treatment and outcomes due to the small number of children in our study.
One systematic review reported that color and score improvements are equivalent instruments for measuring outcomes in lasertreated PWS. 18 In our study, we also investigated the correlation between color and score improvement. Darker lesions are assumed to have greater vascular density and a deeper vascular structure, which would result in poor outcomes. However, we did not find any Laser-associated purpura is a common complication. 12 This was also observed in our study. It is the most favorable endpoint for PDL, which was used in the majority of our patients. Purpura usually lasts for days or weeks, causing cosmetic concerns. Therefore, pretreatment counseling is mandatory. Proper camouflage is beneficial during the post-procedural period. Hyperpigmentation and blebs can be avoided with use of the appropriate laser settings and avoidance of sun exposure.
Our study had a few limitations. First, as it was retrospective study, we observed incomplete data during the chart review.
Second, it was a single-center study. A multicenter study will enhance our knowledge in this particular field. Finally, the use of nonuniform treatments resulted in an inability to compare the efficacy of different lasers. We included patients who underwent more than one laser treatment. We initially used PDL to treat PWS. However, in the later sessions of some difficult cases, such as hypertrophic PWS, we switched to the 1064 long-pulse Nd:YAG, which targeted water as a chromophore and could penetrate lesions more deeply. Laser treatment should be individually tailored. Choosing the laser type depends on patient clinical findings and physician experience. Some patients may require a combination of several laser types to achieve excellent results. Thus, the outcomes of this study faithfully reflect real-life practices.
In conclusion, laser irradiation is a promising treatment for PWS.
Multiple treatment sessions are required to achieve 50% improvement. Long-term follow-up is recommended to achieve optimal therapeutic outcomes.

ACK N OWLED G M ENTS
I am extremely grateful to Asst. Professor Kunlawat Thadanipon for the valuable suggestions regarding the statistical analysis.

CO N FLI C T O F I NTE R E S T S TATE M E NT
The authors declare no conflicts of interest.

DATA AVA I L A B I L I T Y S TAT E M E N T
The data that support the findings of this study are available from the corresponding author upon reasonable request.