Treatment of Melasma on Darker Skin Types: A Scoping Review

: Melasma is a challenging chronic skin condition associated with hyperpigmentation and unknown aetiology. This scoping review maps evidence of available treatments and their effectiveness in darker skin types. A comprehensive, systematic online search was conducted in Scopus, PubMed, CINAHL Complete, Cochrane, ScienceDirect, and Web of Science Core Collection. All eligible titles were exported to an EndNote20 library (Clarivate analytics, US). Thematic content analysis was performed to summarise data on current melasma treatments for darker skin types. The quality of included articles was appraised using the Mixed Methods Appraisal Tool (MMAT) 2018 version. A total of 2863 articles were retrieved from the databases, and 10 met the eligibility criteria following abstract and full-text screening. Our ﬁndings demonstrate that topical treatments, chemical peels, lasers, and tranexamic acid are common treatment modalities used in darker skin types. Although these treatments may be effective in the short term, they bring about undesirable side effects and sometimes worsen or result in reoccurrences of melasma. Based on the evidence mapped, current treatment modalities are not suitable for darker skin types. There are very few studies conducted on individuals of African descent. Further research is necessary to investigate treatment interventions that may be user-friendly when dealing with darker skin types.


Introduction
Melasma is a common and acquired human melanogenesis dysfunction characterised by symmetric hyper-pigmented macules with irregular borders and patches of light to dark-brown skin on the face's forehead, cheeks, upper lip, and chin [1][2][3].While being characterised as a facial disorder, melasma also occurs in non-facial areas such as the chest, arms, and neck [4].Although melasma pathogenesis has not been linked to any specific gene, it is found to be more common in females and males of Hispanic, Asian, and African descent [5][6][7][8].A study conducted in South Africa reported that pigmentation disorders are among the top five skin conditions, with melasma accounting for many of the cases [9].
The specific cause of melasma remains unknown; however, its onset is often linked to various aetiological factors.Pregnancy, the use of oral contraceptives, improper safe sun practices, pollution, stress, genetic predisposition, hormonal changes, some cosmetic ingredients, phototoxic drugs, and hypothyroidism have been associated with the onset of melasma [10,11].Some studies suggest a genetic predisposition for melasma in those of African ancestry [12,13].Exposure to ultraviolet (UV) rays is another risk factor for melasma as it is more prevalent in equatorial countries.Melasma is difficult to treat due to its complicated pathogenesis, particularly in darker-skinned individuals [14,15].Melasma is traditionally treated using a variety of treatment strategies such as trigger avoidance, photo-protection, chemical peels, lasers, and topical medications such as Kligman's formula and hydroquinone, with variable success rates [1,10,16,17].
Being a facial-disfiguring lesion, melasma has been reported to impact negatively upon patients' overall well-being.Quality of life (QoL) studies have revealed that melasma affects interpersonal interactions, especially since melasma alters a person's appearance [18][19][20][21][22].The World Health Organization (WHO) describes QoL as a multi-dimensional concept that assesses a person's insights into holistic well-being.This includes physical, mental, and social health [3,15,[22][23][24].The feelings of shame, frustration, embarrassment, suicidal thoughts, low self-esteem, and demotivation to socialise have also been reported [19,25].Many patients afflicted with the condition may spend a fortune on medical and cosmetic treatments; sadly, most treatment results are poor and unsatisfactory.
Challenges in treating melasma have resulted in a plethora of anti-melanogenesis treatments.Hydroquinone is a first-line topical medical depigmentation therapy that is used alone or in combination with other treatments such as lasers and tranexamic acid [26][27][28].The majority of documented treatments have relied primarily on the use of chemical methods [29][30][31][32], laser therapy [33][34][35][36][37][38], and topical creams [39][40][41][42][43].However, the effectiveness of these therapeutic modalities is limited by their adverse effects, especially in darker skin types [44].For this study, darker skin types refer to the Fitzpatrick skin type scale (i.e., types IV-VI).Recent research has revealed the effectiveness of tranexamic acid (TA) against hypermelanosis; however, shortfalls in the number of controlled studies, a lack of follow-up treatment periods, and the establishment of optimum doses remain underexplored and provide scope for further investigation.Most documented studies have been performed with Indian and Asian patients, making it a challenge to generalise the results [11,[45][46][47][48].
Despite numerous treatment options available to treat melasma, it remains a medical concern, as the problem still exists.There is growing interest in the potential use of medicinal plants in managing hypermelanosis and uneven skin tone, as they are perceived as being safe [49].Historically, one of the most medicinally beneficial plants in rural areas of South Africa's Eastern Cape and KwaZulu-Natal provinces is the Cassipourea flanaganii (C.flanaganii).The ground crude bark is used to protect the skin from the sun, enhance the complexion, and even out skin tone [49][50][51][52].The use of C. flanaganii as a hypopigmentation therapy requires further study to investigate its potential use as a substitute for hydroquinone.Recently, C. flanaganii isolates were identified to have low cytotoxicity toward melaninproducing skin cells in vitro, as demonstrated by a significant decrease in melanin content in these cells [50].The purpose of this scoping review is to identify and summarise the most effective, tolerable, and safe treatment interventions for melasma in people with darker skin.Gleaned evidence will be used to promote best practices and add value to the development of products specifically for darker skin individuals.

Overview
This scoping review aims to develop a novel approach to enhance the scientific understanding of the use of medicinal plants for the treatment of hypermelanosis, which can be produced locally in South Africa, and which may help address melasma in people with darker skin.
The research was carried out following the study protocol available at https://osf.io/ru3jc/(accessed on 25 January 2023).The review was guided by the Arksey and O'Malley framework [53], further advanced by Levac et al., and the Joanna Briggs Institute 2020 recommendations [54].By this methodological framework, the review was carried out in the five stages listed: 1. determining the research question, 2. locating relevant studies, 3. study selection, 4. data charting, and 5. data collation, summarising and reporting on the articles.The sixth optional stage involving consultation (knowledge translation) with stakeholders to provide greater insight beyond those found in the literature (Arksey and O'Malley (2005) [53]) was not required, as this scoping review did not include stakeholder consultation.The findings of this study were reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) checklist, File S4 [55] available on figshare at 10.6084/m9.figshare.21730970(accessed on 27 January 2023).

Identifying the Research Question
This paper aims to systematically evaluate evidence from the literature on treatment interventions used for melasma in darker-skin-type individuals and to answer the research question: What are the most effective, tolerable, and safe treatment interventions for melasma in darker skin types?To answer this research question, the Population, Exposure, and Outcome (PEO) framework, as illustrated in Table 1 below, was used to assess the research question's eligibility for review.Both males and females with darker skin types and melasma on the face participated in the studies.For exposure, all studies on melasma treatments were included.In the outcomes, the efficacy of treatment, reported toxicity, and side effects were all considered.

Outcome
(1) Was the treatment effective?

Identifying Appropriate Studies
We carried out a broad and replicable literature search using six academic databases, namely Scopus, PubMed, Cochrane, CINAHL Complete, ScienceDirect, and the Web of Science Core Collection (Supplementary Material File S1) to retrieve published peerreviewed articles reporting on primary research based on experiments, observations, or simulations [56].All articles published from database inception to November 2021 were considered.Search strategies were developed by the principal investigator (PI) together with a librarian.A combination of free-text keywords as well as Medical Subject Headings (MeSH) was used when conducting the literature searches.Search terms used included "melanosis", "melasma", "skin pigmentation", "dyschromia", "hyperpigmentation", "chloasma","Fitzpatrick skin IV to VI", "Fitzpatrick skin IV-VI", "Fitzpatrick VI", "Fitzpatrick IV", "Black", "Indian", "mixed ancestry", "darker skin type*", "African Continental Ancestry Group", "mixed race", "quality of life", "prevalence", "therapy", "therapeutics", and "treatment".The Boolean terms OR and AND were used to combine the keywords into search strings.For example: (melasma OR pigmentation OR dyschromia OR hyperpigmentation OR chloasma) AND ("quality of life" OR prevalence OR therapy OR therapeutics OR treatment).
Peer-reviewed articles in any language were considered if they met the following criteria for inclusion:

•
Evidence of facial melasma Studies were excluded if they were review studies or grey literature or if they did not meet any of the criteria for inclusion.

Selecting Studies
An EndNote20 library (Clarivate analytics, US) was used to save all eligible articles as well as identify and eliminate all duplicates.Articles were screened in three stages according to the title, abstract, and full text.A screening tool that factored the inclusion and exclusion criteria and the PEO elements was created by the principal investigator and piloted by the reviewers using 10 articles.The tool was then adjusted accordingly.
In the second phase of selection, the PI, in parallel with the co-reviewer (TV), screened the abstracts of the included articles using the screening tool.Following this, the reviewers discussed the selected articles and any discrepancies were resolved by consensus.In the last phase, two reviewers (NM) and (TV) screened the full-text articles for all eligible abstracts.Any discrepancies were resolved by a third screener (SG).The level of agreement after the full-text screening was determined using Kappa statistics.The following is how the Kappa statistics were interpreted: 0.1 indicates no agreement, 0.10-0.20 indicates no to slight agreement, 0.21-0.40indicates fair, 0.41-0.60indicates moderate, 0.61-0.80indicates substantial, and 0.81-1.00indicates almost perfect agreement.

Charting the Data
Using an electronic data-charting form, data were collected from each of the included articles.For consistency, the two independent reviewers piloted the data-charting form with a random sample of five included articles.All recommended modifications were implemented by the feedback provided by the two independent reviewers.Extracted data from the included studies summarised the most effective, tolerable, and safe treatment interventions for melasma on darker skin types.

Quality Appraisal
The Mixed Methods Appraisal Tool (MMAT), version 2018, was used to assess the methodological quality of the included studies [57].As stipulated in the MMAT guidelines, each article's research design was evaluated.Each study's scores were calculated as a percentage, and then a specific rank was allocated.Studies were ranked low in quality if the score was below or equal to 50%, deemed average quality if the score was between 51 and 75%, and received a high-quality rating if it ranged from 76 to 100%.

Results Collection, Summarisation, and Reporting
We used thematic analysis to extract evidence to answer the research question.The emerging themes from the data were narratively summarised.

Ethical Consideration
This scoping review did not require ethical approval as the review relied on the synthesis of existing literature available in the public domain.

Screening Results
The flowchart of the PRISMA-ScR method (Figure 1) reports on the inclusion and exclusion of studies used for this review.Firstly, the literature search yielded 2853 articles (Table 2, also available at 10.6084/m9.figshare.21730970)(accessed on 27 January 2023)) from six different databases.Following the removal of 867 duplicate titles, 1986 titles were identified to be eligible.A further 1566 records were removed.The remaining 420 articles were included for abstract screening.Of the 420 articles, 341 articles did not meet the inclusion criteria, as some studies were conducted on all skin types and some were conducted on animals or investigated extra-facial melasma and were excluded.The remaining 79 articles met the inclusion criteria for full-article screening.Following the full-article screening, 69 articles were excluded, as 42 articles included all skin types, 20 articles did not meet the eligibility requirements, 1 article was based on an animal study, 4 articles were reviews (not original research), and 1 was a case report.Ultimately, data were extracted from 10 articles.There was 96.2% agreement versus 50.0%expected by chance, which, according to the Cohen Kappa value of 0.901 (SE = 0.056, t = 7.960, p < 0.001), is indicative of an "almost perfect" agreement [58].Similarly, McNemar's Chi-squared statistic, χ 2 = 0.333, suggests that there is no statistically significant difference in the proportions of yes/no responses by the reviewers with a p-value = 0.564.This confirms the agreement between the reviewers.

Characteristics of the Studies Included
Table 3 summarises the characteristics of the articles included.The studies that were considered were published between 1994 and 2020.These articles provide evidence of research carried out in the listed countries: India [6,11,[59][60][61], USA [62], Thailand [63], South Africa [15], Korea [64], and China [65].Findings from these articles were conveyed as randomised comparative [11,60], prospective randomised single-blind [6], prospective single-blind [6,59], randomised vehicle-controlled [62], prospective pilot [65], randomised controlled trial [8], and experimental studies [15,63,64].The primary healthcare settings included dermatology outpatient clinics, medical schools, tertiary care hospitals, as well as private practice rooms.Study participants were mainly Indian [6,11,[59][60][61].The total number of participants from all included studies was 420, of which 398 were female participants and 22 were male (Table 3).Drop-outs due to side effects did not make a significant difference in any of the included studies as the number was very low [6].

The Level of Evidence
The methodological quality of the included articles was evaluated using the MMAT tool, 2018 version [57].The ten studies that were evaluated for methodological quality received scores ranging from 70% to 90%, which indicated that their methodology was of high quality.Seven studies received the highest quality rating of 90%.Two studies scored 80%.The remaining article scored 70% (Files S2 and S3 available on figshare at: https://10.6084/m9.figshare.21730970accessed on 25 January 2023)).

Main Findings
The threads that emanated from the included articles were topical treatments, chemexfoliation, lasers and lights, and oral treatments.All of the included articles demonstrated at least one facet of PEO on melasma.The findings from all included studies are summarised in Table 4.

Topical Treatments Azelaic acid (AZA) Cream
One study reported the efficacy of the topical application of 20% AZA cream as a monotherapy compared to sequential therapy with a steroid when treating melasma in Indian patients [59].A study conducted to compare the efficacy of 20% azelaic acid cream monotherapy versus sequential therapy in the treatment of melasma in dark-skinned patients was conducted [59].The overall response, which included clinical evaluation and photography, revealed melasma lightening.The improvement was significantly greater for those who received sequential therapy compared to those who received 20% AZA cream only.Although the difference remained significant at 24 weeks, as many as 96.7 and 90% of patients in each group had satisfactory to excellent treatment responses, respectively.Side effects were reported, though they were regarded as local irritant effects.Six patients reported itching and burning after using the 20% AZA cream, although this subsided with continued usage.In five cases, strong topical steroids were used, but the symptoms resolved once the steroids were stopped.As the side effects were only temporary, the patients were given AZA cream after eight weeks.It was not conclusive whether continuous treatment was required to manage melasma after the end of the study period.

Retinol/Tretinoin
The effects of topical retinoic acid (RA) on melasma in African Americans were studied in a randomised, vehicle-controlled clinical trial.The study trial was started with moderate to severe face hypermelanosis that was clinically compatible with melasma [62].Follow-up evaluations were performed after 2 and 4 weeks of therapy, as well as at monthly intervals thereafter.The change in clinical appearance was compared to the baseline at each visit.The overall response showed improvement within the tretinoin treatment group compared to a 10% improvement in the vehicle group.Melasma lightened after 40 weeks of tretinoin treatment, according to colourimetric measurements.Histologic examination of the affected skin revealed that the tretinoin group had significantly less epidermal pigmentation than the vehicle group.The most common side effect was mild "retinoid dermatitis," which occurred in 67% of the tretinoin-treated patients (Table 4).

Chemical Peels
Three studies investigated the application of various chemical peels to treat melasma.A comparative study assessed the effectiveness and tolerability of glycolic acid (GA), salicylic acid (SA), and mandelic acid (MA), as well as phytic combination peels [6].In this study, participants were divided into three groups: group A used glycolic acid (35%), group B used SM acid (20% salicylic/10% mandelic acid), and group C used a phytic combination peel.It was evident from the results that both glycolic and SM acid peels were equally effective and safe treatment options for melasma in Indian skin, and they were more effective than phytic acid peels [6].Several undesirable side effects, including post-peel pigmentary changes, were reported as mild (Table 4).
The focal trichloroacetic acid (TCA) peel method presented an efficient modality for the treatment of melasma, without major complications [64].Periocular melasma was treated with 10% to 20% TCA, while the rest of the facial melasma lesions received 30-50% TCA.Moreover, the choice of concentration was determined by the caustic chemical used, the concentration, the intensity of keratocoagulation, and the effectiveness of the peel modulated by the concentration and amount of each agent used, as well as the mode and number of applications, skin type, and dermatologic condition being treated.By pressing firmly with a sharpened wooden applicator, the TCA peel was applied to a focal pigmented area.The coagulation of the epidermal and dermal proteins was characterised by a frosted appearance and used as an indicator of the peel depth, marking the endpoint.TCA was applied selectively to each pigmented lesion, resulting in evenly frosted spots.Independent physicians who were double blind evaluated photographs taken before treatment and 6 months after the completion of treatment for independent clinical assessment.Six patients rated the results as exceptional (over 70% of the lesions disappeared), five patients indicated the results as good (50% to 70% of the lesions resolved completely), five obtained fair results (30% to 50% of the lesions disappeared), and four experienced poor results (less than 30% of the lesions disappeared).Although complications were regarded as insignificant, transient post-inflammatory hyperpigmentation occurred, which necessitated the use of 5% hydroquinone treatment (Table 4).
In one study, the therapeutic response of melasma in Indian women to GA (20-35%) versus TCA (10-20%) for chemical peeling was compared [60], and both men and women with epidermal melasma were enrolled in the study.The participants were split into two groups.GA (20-35%) was used in Group 1 and TCA (10-20%) was used in Group 2. Before the commencement of the study, both groups were enrolled in a pre-peel program that involved the daily application of 1% tretinoin at night before the peel procedure.The faces were divided into two sections: the right and left foreheads, the left and right cheeks, the nose and glabella, and the perioral area.A 20% glycolic acid peel and 10% TCA were applied for two minutes; the second peel, 20% GA/10%TCA, was applied for four minutes; the third peel application comprised 35% GA/20% TCA for two minutes; the fourth peel, 35% GA/20% TCA, was applied for four minutes.Both groups were treated the same, but the difference was the peel concentration, as group 1 was treated with GA (20-35%) and Group 2 with TCA (10-20%).All peels were applied every two weeks.The results of the study showed that the application of 20% GA cream at night for 2 weeks, followed by an increase in the GA and TCA concentrations of a facial peel for 2-4 min every two weeks for three months proved to be an equally effective treatment.There was no difference in the peels after six weeks; however, improvement in the TCA Group was noted after two weeks, compared with an improvement only after six weeks in the GA group.Side effects were well-treated (Table 4).

Lasers and Lights
Four studies evaluated the use of different lasers and lights as monotherapy or used with other therapies.One study assessed the efficacy of LED [15], another investigated the application of Q-switched neodymium-doped yttrium aluminium garnet (Nd-YAG) lasers combined with Kligman's triple combination [61], and the last two evaluated the safety and effectiveness of the picosecond alexandrite laser [63,65].
In a prospective trial, the picosecond alexandrite laser (755 nm), using a diffraction lens array and a flat optic, was utilised to treat refractory melasma [63].All patients in this study had stopped all previous treatments/medications for at least one month before receiving treatment with the picosecond alexandrite laser.Participants were separated into two groups.Group 1 participants were treated with the picosecond alexandrite laser flat optic while group 2 participants were treated with the picosecond alexandrite laser with a diffractive lens array.After the study, patients showed a significant improvement with the diffractive lens array compared with the flat optic lens.Both groups were dissatisfied as they experienced macular hypopigmentation (Table 4).
A split-face randomised controlled trial examined the safety and effectiveness of Q-switched neodymium-doped yttrium aluminium garnet laser (QSNYL) and topical creams (TCs) in treating melasma compared to the efficacy of 1064 nm Q-switched Nd-YAG laser and modified Kligman's formulation [61].Both QSNYL and TC were studied as monotherapy for their efficacy.Seventeen patients (37.8%) had epidermal melasma, while the rest had dermal or mixed melasma types.Participants were randomised into two groups.Group A received QSNL treatment while group B was treated daily with TC.After the study period, four different outcome measures were used to assess treatment efficacy.The results revealed an overall improvement in both groups after 16 weeks.There were no statistically significant differences between low-fluence QSNYL and TC as monotherapy.The reappearance of melasma after stopping the therapy was one of the reported side effects experienced (Table 4).
Omnilux LED showed improvement in melasma in individuals with skin types V-VI [15].Participants in this study were purposefully divided into two groups based on their skin tone.Both groups received two LED treatments for 12 weeks twice a week.After the study period, both groups showed improvement.Participants with skin type V rated their melasma to have improved more compared with that of skin type VI participants.In this study, there were no reported side effects; however, the study time was long, i.e., nine months, and people who suffer from melasma tend to be less patient (Table 4).

Tranexamic Acid
One study evaluated the effects of oral tranexamic acid (TXA) compared to intradermal microinjections of TXA when treating melasma [11].In this comparative study, patients were randomly allocated to one of two groups (intradermal or oral), which comprised 50 participants [11].The results of the study revealed that both treatment methods were equally effective.Some patients reported adverse effects, which necessitated treatment with oral ranitidine 150 mg twice daily, and some reported relapse (Table 4).

N/A
Group A: 20% AZA cream, twice-daily application to one half of the face for 24 weeks.Group B: 0.05% clobetasol propionate cream, applied for 8 weeks only and then to be followed by 20% AZA cream only for the next 16 weeks on the other half of the face.Sarkar, 2002 [59].
Prospective, single-blind, right-left comparison pilot

IV-V 24 weeks
At 4, 8, and 16 weeks, the lightening of melasma was significantly more marked on the side receiving the sequential therapy rather than the side receiving only 20% AZA cream (p < 0.001).However, at 24 weeks, although the difference was still significant (p = 0.0052), as many as 96.7 and 90% of patients of each group (sequential therapy and AZA) had good to excellent responses to treatment 24 weeks Atrophy, telangiectasia, burning, erythema itching, acneiform eruptions.Three patients did not experience any changes.
Group A skin type V: twice-weekly LED 633 nm followed by an 830 nm treatment 2 days later.Group B skin type VI: twice-weekly LED 633 nm followed by an 830 nm treatment 2 days later.Mpofana and Abrahamse, 2018 [15].

Experimental V-VI 12 weeks
Decreased MASI mean from 40.66% at baseline to 26.85%.Improved MHGS scores as shown by a p-value of 0.000 at a <0.05 level of significance.VISIA complexion analysis as well as histology images showed improvement of melasma.
Response graded by patients as being "Excellent Response" 36 weeks N/A N/A Moderate to severe burning, erythema, post-peel cracking.N/A Group A: 0.1% tretinoin cream application of "pea-sized" amount of cream and slowly increase the amount used every night to increase tolerance.
Group B: identical-appearing, colour-matched vehicle cream, application of "pea-sized" amount of cream and slowly increase the amount used every night to increase tolerance.Kimbrough-Green [62].The pulse duration was 750 ps.An 8-mm spot size and fluence of 0.4 J/cm2 was used over the target area with 2 passes per treatment area and around 2000-2500 passes in total.The repetition rate was 10 Hz.Treatments were performed in 4-to 6-week intervals.

Prospective, pilot IV N/A
The mean MASI score of 20 patients was 9.4 ± 4.7 at baseline, which improved significantly to 6.9 ± 3.7 after 3 sessions of ps laser therapy (p< 0.001).The VISIA analysis showed improvement on the forehead, although only spots (p = 0.007) and porphyrins (p = 0.032) were markedly improved.In both malar regions, VISIA analysis showed significant improvement in UV spots (p = 0.044), brown spots (p = 0.017), and porphyrins (p = 0.02).
Melasma is a disfiguring skin condition that is more common in women with darker skin [15].In one cross-sectional, multi-centric, clinico-epidemiological study of melasma in India [66], there was a strong correlation between family history and the prevalence of melasma, suggesting genetic predisposition [67].Sun exposure is a major cause of melasma, so a broad-spectrum sunscreen with an SPF of 50 or higher was always recommended [1,5,15].Other factors that may contribute to melasma include concurrent medication, chronic disease, multiple pregnancies, and the use of oral contraceptives [66].

Topical Treatments
Melasma is managed with TC cream as a first-line treatment.Kligman's formula contains 4% hydroquinone, 0.05% tretinoin, and 0.01% fluocinolone acetonide [68].TC shows better results, as hydroquinone (HQ) prevents melanin production by inhibiting tyrosinase, whereas tretinoin has exfoliating properties that help enhance penetration.However, with this combination, it has been observed that it is easy to re-pigment due to the inflammation caused by tretinoin [69].HQ 2-4% cream is often used; it has been reported to cause uneven depigmentation, contact dermatitis, post-inflammatory hyperpigmentation, temporary erythema, burning, and ochronosis [59,70].
Another commonly used TC is tretinoin.It is either used with other topical whitening creams as a penetration enhancer or alone.It reduces pigmentation by inhibiting tyrosinase induction as it disrupts pigment transfer and accelerates epidermal turnover [62,71].The use of tretinoin has been proven to be effective; however, lightening takes more than 24 weeks, which is a lengthy period for patients, and thus inconvenient.Additionally, being a corticosteroid, it brings about undesirable side effects such as local irreversible thinning of the skin, scaling, dryness, burning, erythema, stinging, contact dermatitis, perioral dermatitis, or acne rosacea and hypertrichosis in some cases [62,70].Although the side effects are reversible, retinoid dermatitis can cause hyperpigmentation, particularly in people with dark skin [62].

Chemical Peels
Superficial and medium-depth chemical peels, particularly glycolic acid, are effective in melasma but are not ideal for the treatment of melasma, especially when used alone [6,7,60].There is a tendency for irritation, increased dryness, and photosensitivity.After chemical peels, darker skin types may experience pigmentation changes, including areas of hypopigmentation and hyperpigmentation [10,68].TCA has long been used as a peeling agent in the treatment of several pigmented lesions, including melasma and photoageing.The use of higher TCA concentrations for deeper peels is associated with increased risks, primarily in dark-skinned patients whose skin tends to develop post-inflammatory hyperpigmentation [64].

Lasers and Lights
Although both ablative and non-ablative lasers can have a significant impact on melasma, the results are not always consistent, and complications have been reported.Adverse effects such as significant epidermal damage and peripheral hyperpigmentation, rebound hyperpigmentation, mottled hypopigmentation, and petechiae have been recorded in varying degrees of frequency, more especially for those with darker skin tones [72,73].

Tranexamic Acid
TXA can be used safely and effectively to treat melasma in various forms such as oral, intradermal, or topical applications.Its safety profile has been thoroughly investigated [8,11,26,40,47].However, because no controlled trial studies have been conducted in other ethnic groups, such as Africans, additional data collection and risk assessment are required for these groups [74].

Sun Protection
Sun exposure is completely prohibited when treating melasma.Daily sun exposure, which occurs with typical daily activities in sunny climates, has a detrimental effect on therapies for melasma [8,63].In some countries, myths that darker skin types do not get sun damage still exist [15], and there is a need for education on the importance of sun protection in darker skin types.

Implication for Research and Practice
In this study, we found that there are a variety of treatment interventions to treat melasma.Despite the excessive availability of treatment, melasma remains a huge frustration both to the people suffering from it and the skin specialists managing it, as there is currently no cure.Melasma is not just a cosmetic concern, as it affects quality of life.Most research recorded on darker skin types has been predominantly conducted on Indian skin types.There is limited research for African or mixed-ancestry groups of people, so further inclusive research is necessary.We recommend primary studies and clinical trials investigating the use of medicinal plants to treat melasma.We also recommend that the psychological aspect should be considered when dealing with melasma.

Strengths and Limitations
One of the strengths of this scoping review is that there were no language limitations or time frames applied to the study, which allowed us to comprehensively cover the available peer-reviewed literature.Despite the exclusion of review articles and grey literature sources, the range of evidence was broad, as it included evidence from both qualitative and quantitative methodologies.

Conclusions
Melasma remains a huge medical burden.It is not only a cosmetic concern.Treating melasma is cumbersome since the therapy options typically include risks of pigmentary change, especially when dealing with darker skin types.Due to its high recurrence rate, many therapeutic techniques have been explored with minimal effectiveness but greater side effects.Chemical peels, tretinoin, tranexamic acid, lasers, and lights are all options for therapy.However, while providing brief minor relief, they have also been associated with a high rate of complications, including the worsening of melasma.Additionally, they are not appropriate for all people with darker skin.We have observed in this review that most studies have been conducted up to skin type V.We hope that this scoping review can bring further insight into the need for a suitable treatment for all skin types.There is a need for clinical trial inclusivity of all people with darker skin types, as the majority of research has been done on Indians.Exploring the effects of Cassipourea flanaganii, as it has demonstrated antityrosinase effects in vitro, may be beneficial and may add to the melasma treatment armamentarium.Cassipourea flanaganii could make more targeted therapy available for all skin types in the future as there is a dire need for a novel relief that will be suitable for all skin types.

Figure 1 .
Figure 1.Flow diagram demonstrating the literature search and study selection.

Figure 1 .
Figure 1.Flow diagram demonstrating the literature search and study selection.

Table 1 .
The framework for determining the research question's eligibility.
Determinants Population Darker-skin-type people (skin types IV-VI) with diagnosed epidermal, dermal, or mixed melasma.Exposure All types of treatment for melasma, e.g., self-applied topical interventions or combinations of topical interventions and oral interventions.

Table 2 .
Results from searched data bases.MeSH Terms] OR Melasma [Text Word] OR melanosis [Text Word] OR "skin pigmentation"[MeSH Terms] OR Skin Pigmentation [Text Word] OR dyschromia [Text Word] OR "hyperpigmentation"[MeSH Terms] OR hyperpigmentation [Text Word] OR Chloasma [Text Word] AND (humans[Filter])) AND (("Quality of Life"[Mesh]) OR "Prevalence"[Mesh] OR "quality of life"[TW] OR prevalence[tw] OR "therapy"[Subheading] OR "therapeutics"[MeSH Terms] OR treatment[Text Word] AND (Fitzpatrick skin IV to VI[TW] OR Fitzpatrick skin IV-VI[TW] OR Fitzpatrick VI[TW] OR Fitzpatrick IV[TW] OR Black[TW] OR Indian[TW] OR "mixed ancestry"[TW] OR "darker skin type*"[TW] OR "African Continental Ancestry Group"[Mesh] OR "mixed race"[TW] 888 15/10/21 Scopusmelanosis OR Melasma OR "skin pigmentation" OR dyschromia OR hyperpigmentation OR Chloasma AND "Fitzpatrick skin IV to VI" OR "Fitzpatrick skin IV-VI" OR "Fitzpatrick VI" OR "Fitzpatrick IV" OR Black OR Indian OR "Mixed ancestry" OR "darker skin types" OR "African Continental Ancestry Group" OR "mixed race" AND "quality of life" OR prevalence OR therapy OR therapeutics OR treatment AB (melanosis OR Melasma OR "skin pigmentation" OR dyschromia OR hyperpigmentation OR Chloasma) AND AB (Black OR Indian OR "Mixed ancestry" OR "darker skin type*" OR "African Continental Ancestry Group" OR "mixed race") AND AB ("quality of life" OR prevalence OR therapy OR therapeutics OR treatment) 87 15/10/21 ScienceDirect (Melasma OR hyperpigmentation) AND ("quality of life" OR prevalence OR treatment) AND ("Mixed ancestry" OR "darker skin type) 413 15/10/21 Web of Science Core Collection melanosis OR Melasma OR "skin pigmentation" OR dyschromia OR hyperpigmentation OR Chloasma (Topic) AND "Fitzpatrick skin IV to VI" OR "Fitzpatrick skin IV-VI" OR "Fitzpatrick VI" OR "Fitzpatrick IV" OR Black OR Indian OR "Mixed ancestry" OR "darker skin types" OR "African Continental Ancestry Group" OR "mixed race" (Topic) AND "quality of life" OR prevalence OR therapy OR therapeutics OR treatment (Topic) 361 15/10/21 Cochrane Library melanosis OR Melasma OR "skin pigmentation" OR dyschromia OR hyperpigmentation OR Chloasma [in TitleAbstract Keyword] AND "Fitzpatrick skin IV to VI" OR "Fitzpatrick skin IV-VI" OR "Fitzpatrick VI" OR "Fitzpatrick IV" OR Black OR Indian OR "Mixed ancestry" OR "darker skin types" OR "African Continental Ancestry Group" OR "mixed race" [in Title Abstract Keyword] AND "quality of life" OR prevalence OR therapy OR therapeutics OR treatment [in Title Abstract Keyword]-(Word variations have been searched)

Table 4 .
Summary of included studies.