Patient-Reported Outcomes of Medical Tattooing for Capillary Malformations

A capillary malformation (CM) is a congenital vascular malformation, generally referred to as a port-wine stain, which can be cosmetically burdensome for some patients. Their typical presentation as a pink to dark red macula is caused by a hyperdilation of capillaries and postcapillary venules in the dermis and subcutaneous tissue [1, 2]. Besides physical and functional sequelae, patients often experience emotional and social burden, particularly when located in visible skin areas [3‒8].

The pulsed dye laser is the current gold standard for treatment, but its effectiveness is often not optimal, and CMs may recur [9‒11]. Some patients therefore seek alternative treatments, for example, medical tattooing (MT), also known as dermatography. With MT, exogenous colorfast pigments are permanently deposited below the dermal-epidermal junction of the skin [12]. This indelibly changes the skin color and conceals the CM as a form of permanent camouflage. This therapy was first introduced in the literature in the 1940s [13]. But, since then, only few studies have reported on the effectiveness of MT in CMs [10, 13‒17], possibly due to fluctuating results, experienced complications, or the indirectness to which MT targets CMs. Moreover, those results are based on low-quality studies and often lack patient-reported outcomes (PROs) [10].

PROs refer to the patient’s own perception of well-being, functional status, or QoL regarding healthcare or treatment [18]. Thus, it is possible to directly assess the subjective impact of a certain treatment option on the patient (e.g., satisfaction with treatment outcomes), instead of objectively measuring a disease-related endpoint (e.g., color improvement). The importance of measuring PROs in CMs has previously been recognized, particularly because CMs can greatly affect well-being and QoL [19, 20].

Using a digital survey, we aimed to evaluate if MT deserves a more permanent place in the CM treatment palette. Main study objectives were to assess (1) treatment effectiveness, (2) patient satisfaction with treatment outcomes, and (3) perceived complications in this patient group. Furthermore, we aimed to identify independent factors influencing the effects of tattooing.

This semiquantitative cross-sectional online survey study was conducted by the Amsterdam UMC location AMC, The Netherlands, between September 2021 and April 2022. The Medical Ethics Committee of the AMC waived the need for full ethical review (W21_176#21.191). The Checklist for Reporting of Survey Studies (CROSS) was followed [21].

Study participants comprised patients treated with MT for their CM in the Netherlands between January 2010 and September 2021. Full eligibility criteria are shown in Table 1. A single-stage purposive sampling strategy was applied. First, Dutch MT practices and tattooists were identified from July 2021 to September 2021 via Google and the Dutch Association of Skin Therapists (NVH). If the identified tattooists treated CM patients, they were asked to participate in this study and to complete a survey on the tattooing techniques and products utilized. The participating tattooists searched their patient databases for eligible CM patients and invited them all via telephone or e-mail for participation. At this stage, participants were informed and gave consent to participate in this study. No formal sample size calculation was performed due to the explorative character of this study.

MT involves a tattooing machine that contains a moving needle bar with an adjustable pace (500–3,500 punctures-per-minute) [12, 16]. Numerous needle types can be used, with variances in number, length, diameter, and distance between the needles. The needle characteristics and pace are chosen depending on CM size, skin thickness, and the desired color intensity. Tattooing inks mostly contain carbon black, tartrazine, titanium dioxide, and ferric oxides. The color pigments can be mixed to obtain various subtle color shades to match the normal skin color. An experienced medical tattooist determines the angle (range 10–90°) between the skin surface and the needles to insert the color pigments into the skin below the dermal-epidermal junction, regardless of CM thickness [12, 16]. A test treatment is often performed to see how well the ink settles in the skin. Blebs in CMs are generally not tattooed to prevent complications. Local (topical) anesthesia can be applied. Even though various tattooing machines and ink manufacturers are available, the principles of inserting color pigments in the skin generally remain the same. See supplementary file 1 for used materials per participating tattooing practice. Figures 1-3 show examples of tattooing results.

As there are currently no PRO measures validated for CMs, all study outcomes were measured using an online custom-made survey (secured database Castor EDC) for patients. The survey was in Dutch and included five sections with a maximum of 59 open-, multiple-choice-, and checkbox questions on PROs and patient, disease, and treatment characteristics (supplementary file 2). The majority of the questions and scales addressing the various outcomes were based on a systematic review [19] and the views and experiences of the authors. Noticeability of the CM was derived from the vitiligo noticeability scale [22]. The dermatology-specific DLQI questionnaire was used to assess QoL [19, 23, 24] (supplementary file 3). Total DLQI scores were calculated by adding the score of each question (maximum score 30). A score above 10 denotes the skin condition that severely affects the patients’ life.

Before the start, one Dutch CM patient scrutinized the survey for readability and usability. Between December 2021 and January 2022, the survey was sent to all participants with 2 reminders, each after 2–3 weeks, to minimize nonresponse. Patients aged <18 years were asked to complete the questionnaire with the help of their parents/caregivers. Only fully completed questionnaires were considered for analysis.

Data are presented as numbers (N) and proportions (%) of respondents, means and standard deviations, or medians and interquartile ranges (IQRs), according to the data distribution. Percentage differences were expressed as risk differences with their 95% confidence intervals (CIs). Treatment effectiveness, patient satisfaction with treatment outcomes, the number of MT sessions per patient, and disease characteristics (gender, age, skin type, color, localization, and hypertrophy) were analyzed using a χ² test for ordinal variables and the Mann-Whitney U test for numerical variables. Differences between the type and frequency of camouflage usage before and after MT were investigated with a χ² test.

Ordinal logistic regression analysis was performed to identify independent factors (gender, age, skin type, color, localization, and hypertrophy) associated with treatment effectiveness and patient satisfaction with treatment outcomes. The backward selection method was used to exclude nonsignificant variables from the model.

To perform these analyses, patient and disease characteristics were dichotomized to increase statistical power. Age was converted into age-groups (≤35 years vs. >35 years), skin type was categorized in lighter versus darker skin types (Fitzpatrick skin type 1 and 2 vs. 3, 4, 5, and 6), color was transformed into lighter and darker colors (pink and red vs. dark red and purple), localizations were categorized as visible CMs (at least a CM in the face, neck, or both, including patients with an additional CM in another location), and non-visible CMs (CM in other locations than the face or neck), and hypertrophy was converted into yes/no categories. Also, treatment effectiveness (0–50%, 51–75%, and >75%) and patient satisfaction (very unsatisfied, unsatisfied, neutral, satisfied, and very satisfied) were recategorized.

For all statistical tests, the level of significance was defined by the 95% CIs and p values <0.05. Data were analyzed using the Statistical Package for Social Sciences (IBM SPSS Statistics, version 28, IBM Corporation, Armonk, NY, USA).

A total of 65 MT practices were identified. Of these, 17 practices had experience treating CM patients. Eleven practices did not consent to participate, of which one stated that their only client rejected participation. Another practice responded that they treated too few CM patients and yet another had quit their practice. The remaining eight practices did not report reasons for not participating. Eventually, 6 MT practices consented to contribute and invited their CM patients (n = 127) to participate. Finally, 89 CM patients returned their fully completed surveys (response rate 70%) (shown in Fig. 4), while nine questionnaires were partially completed and therefore excluded. Table 2 displays all baseline participant characteristics.

Seventy-eight percent of the participants had started MT more than 2 years ago. The time between tattooing sessions ranged from one to 4 months in 72% of the patients, and 65% underwent their last tattooing treatment more than a year ago. Overall, patients received a median number of 5 MT sessions (IQR 4.0–8.0), with a range of 1–15 sessions. It was not evaluated if these sessions were required for the same area of the CM or different areas each time. Higher age (>35 y, p = 0.025) resulted in a higher number of treatment sessions. Other patient and CM characteristics had no statistically significant effect on the number of treatment sessions.

In almost all patients, a type of aftercare was applied, mostly consisting of cooling packs (49%) or some anti-inflammatory ointment (26%). Duration and frequency of aftercare use were not recorded. See Table 3 for all participant characteristics and outcomes regarding MT.

Color reductions after MT of >75% were reached in 37% of the patients. Treatment effectiveness significantly differed between both age-groups (p = 0.044) (Table 4); patients in the ≤35 years group had a decreased probability of obtaining >75% color reduction (OR 0.44, 95% CI: 0.20–0.98, p = 0.044) (Table 5).

Seventy percent of the patients stated that the tattoo made the CM “a lot less noticeable,” and 65% strongly agreed that MT had improved their CM. Besides, MT significantly lightened the CM compared to the CM color prior to MT (p = 0.007).

Treatment end results, as reported by the patients, were reached in 60% of the participants. Of the 53 patients from whom end results were obtained, 47% stated that their tattoo had partially faded but needed no further treatment (yet) (follow-up of >1 year in 19/25 patients). Twenty-five percent, however, thought that additional tattooing treatment sessions were necessary.

Eighty-three percent of the patients were (very) satisfied with the MT results. Among the six unsatisfied patients, 1 patient (17%) stated that the MT was not as effective as they had hoped, 1 patient (17%) indicated that their skin was not as clear as before, and 1 patient (17%) stated that the tattoo had completely faded after 2 years. The remaining 3 patients did not elaborate on their reasons for their dissatisfaction.

Patient and disease characteristics had no significant effect on patient satisfaction with treatment outcomes in the bivariate analysis (Table 6). Yet, ordinal logistic regression analysis showed that skin type, color, location, and hypertrophy were independently associated with patient satisfaction with treatment outcomes after correcting for other factors (Table 5): patients with lighter (OR 0.30, 95% CI: 0.13–0.72, p = 0.007), non-facial (OR 0.15, 95% CI: [0.03–0.89], p = 0.036), and hypertrophic CMs (OR 0.30, 95% CI: [0.11–0.82], p = 0.019) had a lower probability of being more satisfied with treatment outcomes (Table 5). Contrarily, patients with lighter skin types were more likely to be more satisfied with treatment outcomes (OR 2.89, 95% CI: [1.23–6.80], p = 0.015).

The perceived complications included bleeding (3.4%), hypertrophic scarring (1.1%), hypopigmentation (1.1%), and 1 patient reported a light halo around the CM. Transient pain occurred in 23% of the patients, with a mean pain level of 4.8 ± 2.2 (VAS scale 0–10). Pain duration was not further specified.

Table 3 demonstrates the type and frequency of camouflage usage before and after MT. Bivariate analysis showed that both type (p < 0.001) and usage frequency (p < 0.001) of camouflage cream significantly lowered after MT.

Forty-two percent of the participants were willing to pay more than €1,000 for the full treatment process, and the majority (71%) were willing to travel one to 3 h per treatment session. The median DLQI score after MT was 0.0 (IQR 0.0–2.0), indicating that the CM, after being treated and at time of the survey, did not affect the study respondents’ lives. See Table 3 for all PROs regarding MT.

The purpose of this study was to assess the patient-reported effects of MT for CMs. MT resulted in a less noticeable CM in the majority of patients. Also, most patients were (very) satisfied with the treatment outcomes, and MT required relatively few sessions to achieve a satisfactory effect. Complications following MT were minor and occurred infrequently. When compared to pulsed dye laser alone, MT appears less effective but leads to fewer and less frequent side effects [10]. MT also reduces daily personal care by significantly decreasing camouflage usage. Overall, these results indicate that, according to the opinions of adult CM patients, MT is a worthy alternative therapeutic option for CMs.

One of the practical challenges CM patients currently face is the limited number of available tattooing practices that treat CMs. Nevertheless, most patients are willing to travel relatively far (up to 3 h) to undergo treatment. Unfortunately, treatment costs are not routinely reimbursed by Dutch health insurances, while the majority of the patients are not willing to pay more than €1,000 for the full treatment. However, the total cost often exceeds this limit.

So far, MT has received little attention in the medical literature. A recent systematic review [10] found only three studies, totaling 56 CM patients that reported on quantitative improvement of the CM following MT [14‒16]. One of these studies, including 19 young CM patients, found that only 11% of the patients reached >75% improvement of the CM, as observed by patients and/or parents [15]. The authors concluded that MT is not recommended for young patients. This may be explained by the still young and developing skin that stretches as the child grows, causing the tattoo pigments to spread throughout the skin. In our study, we found that younger adults also reported less treatment effectiveness. As the skin is already developed in our young adult population, we hypothesize that the perceived lower treatment effectiveness is because younger adults might be more critical about their CM appearance than older adults [25‒27]. Nevertheless, our study generally found better improvement scores compared to the studies from up to 70 years ago [13‒17], which seems plausible as conceivably tattooing techniques and pigments have improved.

Patient satisfaction is not often reported in the available literature on therapeutic strategies for CMs [10]. Although overall satisfaction is high, we found patients were less satisfied with MT when having lighter, non-facial, and hypertrophic CMs. Conceivably, the perceived color difference with the normal skin color after MT is smaller in patients with lighter CMs, causing less satisfaction with treatment outcomes. Furthermore, patients with CMs in visible areas such as the face might be easily satisfied as every small and directly visible effect is experienced as very significant, compared to CMs in non-visible areas. Also, the irregular hypertrophic structure of CMs might become more visible with skin-toned tattooing ink compared to its previously darker color, leading to lower satisfaction scores. Yet, no evidence is available to support these assumptions.

Infections, inflammatory tattoo reactions, scars, ink blow-outs, and neoplasms may occur after MT [28‒31] but have been hardly reported [10, 17]. Our findings show that, apart from transient pain during MT, patient-perceived complications are not severe and uncommon. Some patients reported unsatisfying coverage or fading of the tattoo. This is likely to occur in superficial CMs as the ink is absorbed by the capillaries and post-capillary venules, causing the tattoo to fade faster [17]. Sun exposure (ultraviolet radiation) also increases fading rates due to breakdown of the ink pigments [32]. Streaking of tattoo ink may also result from faulty tattooing techniques [17], and the application of correct tattooing techniques and materials is therefore pivotal [16]. MT thus needs proper training and should be performed by trained tattooists, for example, dermatologists and skin therapists, who should embrace this technique. Furthermore, the light-reflecting properties of the color pigments titanium dioxide and zinc oxide above 400 nm might cause laser therapy to be less effective after previous MT [33]. Also, despite tattooing, CMs can still become more hypertrophic over time [34], possibly requiring subsequent laser treatment. Subsequent laser treatment could, in turn, eradicate the tattoo [35].

Overall, the patients in our sample did not report any impaired QoL. This is in contrast with the existing evidence that CMs often impose a psychological burden on patients, resulting in a decreased QoL [3, 8, 36]. Wang et al. (2017) found that CMs had mild to moderate effects on the QoL in most patients seeking treatment as DLQI scores ranged from 2 to 5 in 52% of the patients and 6 to 10 in 42% of the patients. MT might have led to a better perceived QoL in our population, but this cannot be confirmed as baseline measurements were not performed.

A strength of this study is that it is the first to describe and quantify the results of MT in CMs in a fairly large sample and, more importantly, from the patients’ perspective. Unfortunately, no baseline characteristics of the nonresponders are available, so response bias could not be assessed. Second, as patients were selected from Dutch tattooing practices, the study population might not fully represent the target population, and selection bias cannot be ruled out. Third, long-term results were difficult to assess as most patients completed the survey less than 2 years after their treatment. Fourth, even though the principles of MT have not changed, the application of different tattooing products and techniques might have influenced the reported outcomes. Fifth, due to a lack of validated questionnaires for CMs, a custom-made survey was used. Frequently used scales in similar skin conditions and the DLQI questionnaire were applied to diminish a potential risk of information bias [19, 22, 24]. A sixth limitation is the retrospective study design, which made it more difficult for patients to answer some of the questions, possibly causing recall bias. Seventh, any absences in correlations between variables might have been the result of small subgroups in certain categories, yet variables were dichotomized to diminish this effect. Lastly, we are aware that the study outcomes represent a subjective assessment (e.g., % color reduction), rather than an objective evaluation. Nevertheless, without subjective PROs, the individual impact of treatment cannot be assessed adequately.

Overall, the PROs of MT are encouraging. MT seems to be a valid alternative treatment for adult CM patients in addition to laser therapy, with mild adverse effects. Most patients are (very) satisfied with treatment results, even though color reduction is not maximal. Due to the limited availability of evidence on MT, the current evidence-based treatment of choice for CMs remains laser therapy. Future prospective comparative studies, including patients with similar treatment characteristics and long-term follow-up, are needed to further evaluate the effects of this treatment. Based on this evidence and the individual preferences of patients, we advocate that patients and healthcare providers should decide together whether this therapy is to be applied as a secondary treatment post-laser therapy or as a primary treatment for CMs.

Medical tattooing seems a valid alternative treatment for capillary malformations, with mild adverse effects.

We would like to thank the Dutch Association of Skin Therapists (NVH) for their assistance in identifying and recruiting medical tattooists. Also, we would like to thank the Dutch CM patient for checking the online survey for readability and usability.

This study was reviewed and approved by the Medical Ethics Committee of the AMC, approval number W21_176#21.191. The committee concluded that the Medical Research Involving Human Subjects Act (WMO) does not apply to this study and that an official approval of this study by the committee was not required. The committee waived the need for a written informed consent. Written informed consent was obtained from the patients for publication of the clinical images.

Rinus Souisa is director of Medical Tattoo Innovations (MTI), and Loes Souisa Kooger is voluntary employee at Medical Tattoo Innovations. The other authors have no conflicts of interest to declare.

No funding was received.

Ginger Beau Langbroek: conception, design, acquisition, analysis and interpretation of data, drafting, and revising the work. Julia Felsbourg: conception, design, acquisition, analysis of data, and revising the work. Albert Wolkerstorfer, Sophie ER Horbach, Olivier J van Not, Hans Pieter van Not, Rinus Souisa, Dirk T Ubbink, and Chantal MAM van der Horst: conception, design, and revising the work. Loes Souisa Kooger: conception, design, acquisition, and revising the work. Susan van Dieren: analysis and interpretation of data and revising the work. All authors gave final approval of the version to be published and agreed to be accountable for all aspects of the work.

Dirk T. Ubbink and Chantal M.A.M. van der Horst should be considered joint senior/last authors.

All data generated or analyzed during this study are included in this article and its supplementary material files. Further inquiries can be directed to the corresponding author.