Efficacy of glycolic acid peels in combination with topical therapy in common facial melanosis in skin of color: A randomized clinico-dermoscopic study

INTRODUCTION

Facial melanosis encompasses a broad group of hyperpigmentary disorders, commonly including melasma, lichen planus pigmentosus (LPP), Riehl’s melanosis, post-inflammatory hyperpigmentation (PIH), and others, which are highly prevalent in Indian population. Acquired dermal macular hyperpigmentation (ADMH) is an umbrella term, commonly being used nowadays, including LPP, Riehl’s melanosis, and erythema dyschromium perstans, sharing clinical, dermoscopic, and histopathological features with subtle distinctions. These conditions often cause significant cosmetic concern and psychological distress, particularly because of their chronic course and relapsing nature.^1,2

While melasma has been the most studied facial melanosis, the literature on other disorders such as ADMH and PIH remains sparse, particularly in skin of color.^3,4 Although topical depigmenting agents such as hydroquinone (HQ) and retinoids remain standard first-line treatments, combination regimens involving chemical peels such as glycolic acid (GA) have shown promising results by accelerating epidermal turnover and enhancing drug penetration.^5,6 However, comparative studies assessing such combination therapies with chemical peels in facial melanosis in darker skin tones are limited.

Dermoscopy is a non-invasive diagnostic tool aiding in the diagnosis and monitoring of facial pigmentary disorders. Despite its increasing use in clinical dermatology, dermoscopy is under-utilized as an objective outcome measure in interventional studies on hyperpigmentation, particularly in patients of skin of color, such as the Indian population.^7,8 Furthermore, no standardized dermoscopic scoring system currently exists for evaluating treatment response in facial melanosis.

To the best of our knowledge, there are very few studies evaluating clinico-dermoscopic changes after using topical therapy and GA peel in facial melanosis. This study aims to bridge this gap in the literature by evaluating the comparison of topical monotherapy versus its combination with 35% GA peels in patients with facial melanosis. By integrating clinical and dermoscopic evaluation in facial melanosis in skin of color, this study adds objective data to the existing knowledge and explores the potential of dermoscopy-guided management in improving therapeutic outcomes.

MATERIAL AND METHODS

This was a hospital-based randomized controlled study with a parallel design, an allocation ratio of 1:1, and a superiority framework, designed to evaluate the comparative efficacy of topical therapy versus combination of topical and GA peel treatment in patients with common facial melanosis based on clinical and dermoscopic features. It was conducted in the dermatology outpatient department of a tertiary care center in North India from July 2023 to December 2024. A total of 120 adult patients (18–60 years), clinically diagnosed with facial melanosis including melasma (67), ADMH (42), and PIH (11), were included in the study.

Pregnant/lactating women, active infection over the face, history of any prior treatment for facial melanosis in the past 3 months, and those with known hypersensitivity to any of the treatment given in our study were excluded. Institutional Ethics Committee approval was granted before starting the study.

Patients were randomly allocated using variable block size randomization (2, 4, or 6) which was done using computer generated randomization sequence by an independent person, equally into two groups consisting of 60 patients each. Group 1 included 34 melasma patients, 21 ADMH patients, and 5 patients with PIH, who received topical therapy alone besides broad-spectrum sunscreen. Melasma patients received 4% HQ cream, ADMH patients were given tacrolimus ointment (0.1%), and tretinoin cream (0.025%) was given to patients with PIH. These agents were selected because each pigmentary disorder has its own standard-of-care topical therapy, allowing appropriate management and a valid basis for comparison. Group 2 including 33 patients of melasma, 21 patients of ADMH, and 6 with PIH received combination of topical treatment (as given in group 1) and 35% glycolic peel every 3 weekly for a total of 4 sessions. A detailed history, including the site of onset, duration, rate of progression, any associated symptoms, family history, precipitating factors, and cosmetic use, was taken. All patients were examined in detail for type and morphology and were also subjected to dermoscopic examination using DermLite DL4. Pre and post-treatment photographs were also taken.

Response to treatment was assessed using clinical as well as dermoscopic scores recorded at baseline, 6 weeks, and 12 weeks, in both the groups. The scoring systems used for clinical and dermoscopic evaluation in our study for melasma, ADMH, and PIH are mentioned in Table 1.^9-11

Photographic evaluation was also done at baseline and at 12 weeks of treatment. Any side effects that occurred during the study were recorded and adequately treated. Thyroid function tests and Vitamin B 12 were also assessed in each patient as this is routinely done in our pigmentary clinic.

RESULTS

This study aimed to compare the therapeutic potential of topical therapy and combination of topical with 35% GA peels, on patients with facial melanosis, employing clinical as well as dermoscopic evaluation as key outcome measures. It included 120 patients with facial melanosis, with melasma being the most prevalent diagnosis with 67 patients (55.83%), followed by ADMH with 42 patients (35%), and post-inflammatory pigmentation with 11 patients (9.17%).

Melasma predominantly affected individuals aged 26– 35 years, comprising 24 cases (35.82%). ADMH was more common in the 36–45 years age group, comprising 14 cases (33.33%). Melasma and ADMH showed a female predominance with 55 patients (82%) and 32 patients (76.2%), respectively, while PIH was more common in males with 8 cases (72.73%). The malar area was most frequently involved site overall, particularly in melasma and PIH. In ADMH, temple and neck involvement were more prominent. Demographic details of patients are depicted in Table 2.

The use of cosmetics/dye/mehndi was reported in 45 cases (67.16%) of melasma, 28 cases (66.67%) of ADMH, and 6 cases (54.55%) of PIH, indicating a potential trigger or aggravating factor. Dark brown pigmentation was predominant in melasma and PIH, while slate gray pigmentation was seen in ADMH, reflecting different pigment depths. Thyroid abnormality was seen in 5 cases (7.46%) of melasma and 5 cases (11.9%) in ADMH, suggesting a possible association of thyroid abnormalities with melasma and ADMH, as observed in other studies as well.^12,13 Vitamin B12 deficiency was found in 12 cases (17.91%) and 6 cases (14.29%) in melasma and ADMH, respectively.

In this study, 67 melasma patients were recruited and were randomly allocated to two groups. Group 1 (n = 32) received HQ 4% while the other group received a combination of HQ 4% and 35% GA peels (n = 35). Clinically, the mean baseline modified melasma area and severity index was 7.14 ± 2.33 in group 1 and 7.65 ± 2.91 in group 2 which reduced to 4.24 ± 1.71 and 3.88 ± 1.45, respectively, after 12 weeks, showing significant improvement in both groups (p < 0.05). Overall comparison between both the groups was also found to be statistically significant at the end of 12 weeks, indicating better efficacy of combination therapy. Figures 1 and 2 depict improvement in melasma from baseline till 12^th week in group 1 (HQ 4%) and group 2 (HQ 4% + GA peel 35%), respectively. On dermoscopy, the baseline scores were 6.06 ± 1.34 in group 1 and 6.55 ± 1.2 in group 2 which reduced to 5.10 ± 1.10 and 3.50 ± 1.02, respectively. Mean reduction in scores was statistically significant in both the groups and between both the groups as well at the end of 12 weeks (p < 0.05). Figures 3 and 4 show dermoscopic findings in melasma at baseline and at 12 weeks in group 1and group 2, respectively. Table 3 depicts the comparison of the change in mean mMASI and dermoscopy scores in both the groups over time.

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Figure 1: (a) Clinical photographs of melasma patient at baseline in group 1 (4% Hydroquinone cream). (b) Clinical photographs of melasma patient at 12 weeks in group 1 (4% Hydroquinone cream).

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Figure 2: (a) Clinical photographs of melasma patient at baseline in group 2 (4% Hydroquinone cream + Glycolic acid peel 35%). (b) Clinical photographs of melasma patient at 12 weeks in group 2 (4% Hydroquinone cream + Glycolic acid peel 35%).

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Figure 3: (a) Dermoscopic findings (10x magnification, polarized) of melasma patient at baseline in group 1 (4% Hydroquinone cream) with red star depicting telangiectasia, (b) Dermoscopic findings of melasma patient at 12 weeks in group 1 (4% Hydroquinone cream) with red star depicting telangiectasia (10x magnification, polarized).

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Figure 4: (a) Dermoscopic findings of melasma patient at baseline in group 2 (4% Hydroquinone cream + Glycolic acid peel 35%) with black star depicting pseudo-reticular network, (b) Dermoscopic findings of melasma in a patient at 12 weeks in group 2 (4% Hydroquinone cream + Glycolic acid peel 35%) with black star depicting pseudo-reticular network (Polarized, 10x magnification).

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In ADMH patients, two patient groups were evaluated: Group 1 received tacrolimus ointment 0.1% alone (n = 21), and group 2 received a combination of tacrolimus ointment along with 35% GA peels (n = 21). The mean baseline dermal pigmentation area and severity index (DPASI) scores were 8.24 ± 1.86 in group 1 and 8.18 ± 1.24 in group 2 which reduced to 5.84 ± 1.12 and 4.16 ± 1.02, respectively, at the end of 12 weeks, showing a statistically significant reduction (p = 0.002 and 0.001, respectively). The mean reduction in DPASI score was 2.40 ± 0.74 in group 1 and 4.02 ± 0.22 in group 2 (p = 0.001), reinforcing the greater effectiveness of adding GA peels to topical treatment. Figures 5 and 6 depict improvement in ADMH from baseline till 12^th week in group 1 (tacrolimus ointment 0.1%) and group 2 (tacrolimus ointment 0.1% + GA peel 35%), respectively. Figures 7 and 8 show dermoscopic findings in ADMH at baseline and at 12 weeks in group 1 and group 2, respectively.

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Figure 5: (a) Clinical photographs of acquired dermal macular hyperpigmentation (ADMH) patient at baseline in group 1 (Tacrolimus 0.1% ointment). (b) Clinical photographs of ADMH patient at 12 weeks in group 1 (Tacrolimus 0.1% ointment).

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Figure 6: (a) Clinical photographs of acquired dermal macular hyperpigmentation (ADMH) patient at baseline in group 2 (Tacrolimus 0.1% ointment + Glycolic acid peel 35%). (b) Clinical photographs of ADMH patient at 12 weeks in group 2 (Tacrolimus 0.1% ointment + Glycolic acid peel 35%).

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Figure 7: (a) Dermoscopic findings of acquired dermal macular hyperpigmentation (ADMH) patient at baseline in group 1 (Tacrolimus 0.1% ointment) with black star depicting dots and globules in a reticulate pattern, (b) Dermoscopic findings of ADMH patient at 12 weeks in group 1 (Tacrolimus 0.1% ointment) with blue star depicting dots and globules in semi-arcuate pattern. (Polarized, 10x magnification).

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Figure 8: (a) Dermoscopic findings of acquired dermal macular hyperpigmentation (ADMH) patient at baseline in group 2 (Tacrolimus 0.1% ointment + Glycolic acid peel 35%) with black star depicting dots and globules in reticulate pattern, (b) Dermoscopic findings of ADMH patient at 12 weeks in group 2 (Tacrolimus 0.1% ointment + Glycolic acid peel 35%) with purple star depicting dots and globules in a Chinese-letter pattern. (Polarized, 10x magnification).

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In PIH, patients were divided into two groups: One received 0.025% tretinoin cream and group 2 received a combination of tretinoin cream and 35% GA peels. Clinically, the mean baseline hyperpigmentation area and severity index (HASI) score was 5.76 ± 1.99 in group 1 and 7.05 ± 1.59 in group 2 which reduced to 4.30 ± 1.38 and 3.62 ± 0.73, respectively, over 12 weeks, with significant improvement in both groups (p = 0.002 and p = 0.006). The mean reduction in HASI score was 1.46 ± 0.77 for the topical group and 3.42 ± 0.99 for the combination group (p = 0.018), demonstrating greater efficacy of the combination therapy. Figures 9 and 10 depict the improvement in PIH from baseline till 12^th week in group 1 and group 2, respectively.

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Figure 9: (a) Clinical photographs of post-inflammatory hyperpigmentation (PIH) patient at baseline in group 1 (tretinoin 0.025% cream). (b) Clinical photographs of PIH patient at 12 weeks in group 1 (tretinoin 0.025% cream).

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Figure 10: (a) Clinical photographs of post-inflammatory hyperpigmentation (PIH) patient at baseline in group 2 (tretinoin 0.025% cream + Glycolic acid peel 35%). (b) Clinical photographs of PIH patient at 12 weeks in group 2 (tretinoin 0.025% cream + Glycolic acid peel 35%).

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On dermoscopy, both groups had identical baseline scores of 2.00 ± 0.00, which dropped to 1.43 ± 0.53 and 1.00 ± 0.00 in groups 1 and 2, respectively, with statistically significant improvement in both groups (p = 0.03 and p < 0.001, respectively). The average reduction was 0.57 ± 0.53 for group 1 and 1.00 ± 0.00 for combination therapy. Although the reduction was greater in the combination group, the difference between groups was not statistically significant (p > 0.05). Figures 11 and 12 depict dermoscopic findings in PIH at baseline and at 12 weeks in groups 1 and 2, respectively. Table 4 depicts the comparison of the change in DPASI scores in ADMH patients, HASI, and dermoscopy scores in PIH patients in both the groups over time.

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Figure 11: (a) Dermoscopic findings of post-inflammatory hyperpigmentation (PIH) patient at baseline in group 1 (tretinoin 0.025% cream + Glycolic acid peel 35%), (b) Dermoscopic findings of PIH patient at 12 weeks in group 1 (tretinoin 0.025% cream + Glycolic acid peel 35%). (Polarized, 10x magnification).

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Figure 12: (a) Dermoscopic findings (10x magnifcation, polarized) of post-inflammatory hyperpigmentation (PIH) patient at baseline in group 2 (tretinoin 0.025% cream + Glycolic acid peel 35%) with pink star mark depicting an enhanced (dark brown) pigmentary network, (b) Dermoscopic findings of PIH patient at 12 weeks in group 2 (tretinoin 0.025% cream + Glycolic acid peel 35%) with green star mark depicting light brown pigmentary network (10x magnification, polarized).

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Out of 60 patients in GA peel group, 2 patients (3.3%) reported erythema. All the adverse effects were benign and self-limited and resolved within a week with an antihistamine and mild corticosteroid application.

DISCUSSION

Pigmentary dermatoses such as melasma, PIH, and ADMH are frequently observed in Fitzpatrick skin types III to V, especially in Indian skin. Melasma predominantly affects women aged 30–50, with sun exposure, pregnancy, and hormonal therapy being major aggravating factors. Sarkar et al. reported that 85.5% of melasma cases were female and over 60% were between 31 and 50 years, with nearly 87% citing sun exposure as a trigger.¹⁴ Achar and Rathi also found a 4:1 female-to-male ratio with similar age distribution.¹⁵ These trends align with our study, where melasma cases primarily occurred in middle-aged women with a history of sun exposure and hormonal triggers.

ADMH similarly shows female predominance and onset in the third to fifth decades. Kanwar et al. and Beso et al. documented diffuse facial pigmentation as the most common presentation, which was corroborated in our study.^16,17 Vinay et al. highlighted thyroid abnormalities in 11.3% of LPP patients, which we also observed in our cohort.¹³

Our study demonstrated that the combination of 35% GA peels with topical depigmenting agents significantly improved clinical and dermoscopic outcomes in melasma, ADMH, and PIH compared to topical therapy alone. This aligns with the study by Sarkar et al., who observed better results with combination therapy including GA peels than topicals alone in melasma patients with darker skin types.⁵ Garcia and Fulton emphasized that GA enhances epidermal turnover and allows better penetration of HQ or kojic acid, potentiating depigmentation.⁶ Similarly, Lim reported GA to be particularly effective in treating epidermal melasma in Asian women.¹⁸

In our study, dermoscopy revealed a reduction in pseudoreticular network in melasma and the resolution of grayish pigmentation in ADMH. These findings were consistent with Abdel Hay et al., who emphasized dermoscopy’s value in monitoring pigment clearance and stratifying melasma types.⁸ In PIH, vascular and pigmented dots resolved faster in the combination group, affirming the utility of glycolic peels, as earlier demonstrated by Burns et al. in darker phototypes.¹¹

The safety profile of GA peels was favorable in our cohort, with no adverse effects observed during the study period; however, this should not be interpreted as excluding the possibility of PIH or irritation in broader clinical practice. Sarkar et al. similarly reported minimal irritation and no PIH, supporting the suitability of GA in darker skin types.⁵

Although our study’s follow-up was short, early dermoscopic and clinical improvement suggest promising long-term potential. Future studies with larger cohorts and longer observation are needed to validate these results. In addition, the reliance on monotherapy in one group, although necessary for the study design, does not reflect routine clinical practice and may have contributed to the comparatively better outcomes seen with combination therapy.

CONCLUSION

This study highlights the enhanced effectiveness of combining 35% GA peel with topical therapy in the treatment of facial melanosis in skin of color. Patients receiving combination therapy showed a significantly greater reduction in pigmentation scores over 12 weeks compared to those on topical therapy alone. It also emphasizes the role of dermoscopy in aiding the diagnosis and evaluating the treatment response, therefore holding potential for more frequent use in the future.