Introduction

Hyperpigmentation may be defined as the darkening of the skin due to a melanin deposit in the epidermis or dermis. Benign pigmented lesions, while not physically harmful, may be distressing to patients. Such lesions are thought to be the most common reason for patients seeking dermatological care [1]. They may be congenital, acquired or age-related (e.g., through ultraviolet light exposure), superficial or in deeper dermal layers of the skin, and vary in their difficulty of removal. Benign lesions include dermal melanocytes such as nevus of Ota, melasma, lentigines, and Caféau-lait macules (CALMs), among many others. Removal of such lesions for cosmetic reasons is a procedure that is becoming more and more common in dermatologic practices. Lasers traditionally used to treat exophytic lesions, such as CO2 lasers, have been initially proposed, especially in fractional mode, exploiting their ability to convey energy in the superficial layers of the skin. These devices are associated with a more considerable risk of scarring and pigmentation changes. For this reason, lasers selectively acting on chromophores have been proposed and have obtained better results. Among these devices, different studies indicate that Q-switched lasers deliver high energies in the order of Nano or picoseconds and act selectively on the melanin chromophore sparing surrounding tissues, and therefore may be considered as the most effective and safe treatment for benign pigmented lesions. Lasers, with their ease of use and favourable side effect profile, are commonly used tools for removal of such lesions. Q-switched (QS) lasers have been used to treat benign epidermal and dermal pigmented lesions for the past 20 years. Since their discovery as effective treatment for pigmented lesions, QS modalities including the potassium titanyl phosphate (KTP) 532nm neodymiumyttrium-aluminium garnet (Nd:YAG), alexandrite, and ruby lasers have been shown to be effective in treating benign pigmented lesions [2]. Modern lasers used in dermatology operate under the general principles of selective thermolysis, in which tissue is selectively destroyed by laser energy at specific wavelengths that spare surrounding tissue [3]. Melanin, the primary chromophore in pigmented lesions, has a spectrum of absorption between 351–1,064 nm, making it a suitable target for the 532 nm QS Nd:YAG laser [4,5]. Common side effects of laser treatment in general include purpura, minor bleeding, edema, and erythema, dyspigmentation, blistering, crusting, and scarring [2]. Patients with darker skin types are especially at risk of post‐inflammatory hyperpigmentation (PIH), with a reported incidence of 10–47% [6]. In the current retrospective cohort study, we aimed to examine the effects and safety profile of 532 nm KTP laser on pigmented lesions on the face and neck. The main purpose of this data collection was to evaluate the safety and efficacy of a non-invasive approach for managing pigmented lesions, focusing on the interaction between two outcome measures: physician-assessed improvement and patient satisfaction.

Methods

Clinical Data

In this retrospective cohort study, we collected clinical data from fifteen patients with benign hyperpigmentation who received QS Laser treatment at the Klinika Mjekësore San Luca, Tirana, Albania. The study was approved by the Ethic Committee of the Albanian Ministry of Health (ethics number: 2020-020). All patients were in good physical health with no major underlying diseases, and none had skin disease or took medications that impact skin condition. Study exclusion criteria were previous treatment of the same area(s) at least six months prior to screening, skin type VI, pregnant, intending to become pregnant during study, less than 3 months postpartum or less than 6 weeks after completion of breastfeeding, exposure to the sun or artificial tanning during 3-4 weeks prior to treatment, any remaining suntan, sunburn, or artificial tanning products, active infections in the treatment area, chronic or cutaneous viral, fungal or bacterial diseases, and tattoos in the areas to be treated.

Treatment procedure

The ClearLift applicator, used with the Harmony XL platform (Alma Lasers Ltd., Caesarea, Israel), is a fractional, nonablative, high-power, Q-switched Nd:YAG 1064/532 laser hand piece. Each patient received one session per treated area (face and neck) consisting of one pass of KTP 532 nm with a spot size of 3 mm, a 5X5 pixel tip, and an output energy of 400 mJ/pulse at a discharge frequency of 1 Hz and a fixed pulse time of 20 n sec.

Patients were followed up three months after treatment.

Clinical evaluation

Primary efficacy was assessed at the follow-up visit by comparing the results to photographs taken at baseline. Using the Global Aesthetic Improvement Scale (GAIS), the physician rated the improvement on a scale of 1 to 5 as: worse, no change, improved, much improved, or very much improved. In addition, at the three-month follow-up visit, patients were asked to rate their satisfaction with the treatment on the Likert scale of 1 to 5, from “not at all satisfied” to “extremely satisfied”. The primary safety endpoint was the occurrence of adverse events or complications during treatment and follow-up. In addition, patients were asked to rate their pain during treatment on a scale of 1 to 10, from “no pain” to “severe pain”.

Statistical analysis

Patient demographic characteristics were summarized using descriptive statistics with appropriate measures such as means, standard deviations, and percentages. In addition, a box-whisker plot was used to visually illustrate the distribution and spread of physician and patient ratings, and the Pearson correlation coefficient was calculated to quantify the association between the two ratings. A two-sample t-test was used to analyse significant differences in mean scores between physician-assessed GAIS and patient satisfaction scores, providing insight into the level of agreement in treatment outcomes. Data analysis was performed using Microsoft Excel.

Results

Fifteen patients met the criteria and underwent treatment and follow-up between December 2020 and January 2022. Patients ranged in age from 28 to 53 years, with a mean age of 41.7 ± 7.1 years. There were eleven female patients. Four patients had Fitzpatrick skin type II, eleven patients had type III, and one patient had type IV. Eleven patients were treated on the face and one patient was treated on both the face and neck. Demographic data are presented in Table 1.

Table 1: Patients Demographic.

Efficacy evaluation

The average physician-assessed GAIS score at the 3-month follow-up was 4.2 ± 0.5, whereas the average Likert scale patient satisfaction score was 4.3 ± 0.4. The distribution of patients across different grading scales is shown in Figure 1.

Figure 1: breakdown of patient percentages on GAIS (physician) and Likert (patients) 1-5 rating scales.

The Pearson correlation coefficient between the physician rating of the GAIS scores and the patient rating of the Likert scores was 0.91. Physician (GAIS) and patient (Likert scale) ratings are visually compared in a box-and-whisker plot in Figure 2.