Pigmentation Disorders

Practice Gap

Longitudinal melanonychia (LM) is characterized by the presence of a dark brown, longitudinal, pigmented band on the nail unit, often caused by melanocytic activation or melanocytic hyperplasia in the nail matrix. Distinguishing between benign and early malignant LM is crucial due to their similar clinical presentations.¹ Hence, surgical excision of the pigmented nail matrix followed by histopathologic examination is a common procedure aimed at managing LM and reducing the risk for delayed diagnosis of subungual melanoma.

Tangential matrix excision combined with the nail window technique has emerged as a common and favored surgical strategy for managing LM.² This method is highly valued for its ability to minimize the risk for severe permanent nail dystrophy and effectively reduce postsurgical pigmentation recurrence.

The procedure begins with the creation of a matrix window along the lateral edge of the pigmented band followed by 1 lateral incision carefully made on each side of the nail fold. This meticulous approach allows for the complete exposure of the pigmented lesion. Subsequently, the nail fold is separated from the dorsal surface of the nail plate to facilitate access to the pigmented nail matrix. Finally, the target pigmented area is excised using a scalpel.

Despite the recognized efficacy of this procedure, challenges do arise, particularly when the width of the pigmented matrix lesion is narrow. Holding the scalpel horizontally to ensure precise excision can prove to be demanding, leading to difficulty achieving complete lesion removal and obtaining the desired cosmetic outcomes. As such, there is a clear need to explore alternative tools that can effectively address these challenges while ensuring optimal surgical outcomes for patients with LM. We propose the use of the customized dermal curette.

The Technique

An improved curette tool is a practical solution for complete removal of the pigmented nail matrix. This enhanced instrument is crafted from a sterile disposable dermal curette with its top flattened using a needle holder(Figure 1). Termed the customized dermal curette, this device is a simple yet accurate tool for the precise excision of pigmented lesions within the nail matrix. Importantly, it offers versatility by accommodating different widths of pigmented lesions through the availability of various sizes of dermal curettes (Figure 2).

Histopathologically, we have found that the scalpel technique may lead to variable tissue removal, resulting in differences in tissue thickness, fragility, and completeness (Figure 3A). Conversely, the customized dermal curette consistently provides more accurate tissue excision, resulting in uniform tissue thickness and integrity (Figure 3B).

Practice Implications

Compared to the traditional scalpel, this modified tool offers distinct advantages. Specifically, the customized dermal curette provides enhanced maneuverability and control during the procedure, thereby improving the overall efficacy of the excision process. It also offers a more accurate approach to completely remove pigmented bands, which reduces the risk for postoperative recurrence. The simplicity, affordability, and ease of operation associated with customized dermal curettes holds promise as an effective alternative for tissue shaving, especially in cases involving narrow pigmented matrix lesions, thereby addressing a notable practice gap and enhancing patient care.

Practice Gap

Longitudinal melanonychia (LM) is characterized by the presence of a dark brown, longitudinal, pigmented band on the nail unit, often caused by melanocytic activation or melanocytic hyperplasia in the nail matrix. Distinguishing between benign and early malignant LM is crucial due to their similar clinical presentations.¹ Hence, surgical excision of the pigmented nail matrix followed by histopathologic examination is a common procedure aimed at managing LM and reducing the risk for delayed diagnosis of subungual melanoma.

Tangential matrix excision combined with the nail window technique has emerged as a common and favored surgical strategy for managing LM.² This method is highly valued for its ability to minimize the risk for severe permanent nail dystrophy and effectively reduce postsurgical pigmentation recurrence.

The procedure begins with the creation of a matrix window along the lateral edge of the pigmented band followed by 1 lateral incision carefully made on each side of the nail fold. This meticulous approach allows for the complete exposure of the pigmented lesion. Subsequently, the nail fold is separated from the dorsal surface of the nail plate to facilitate access to the pigmented nail matrix. Finally, the target pigmented area is excised using a scalpel.

Despite the recognized efficacy of this procedure, challenges do arise, particularly when the width of the pigmented matrix lesion is narrow. Holding the scalpel horizontally to ensure precise excision can prove to be demanding, leading to difficulty achieving complete lesion removal and obtaining the desired cosmetic outcomes. As such, there is a clear need to explore alternative tools that can effectively address these challenges while ensuring optimal surgical outcomes for patients with LM. We propose the use of the customized dermal curette.

The Technique

An improved curette tool is a practical solution for complete removal of the pigmented nail matrix. This enhanced instrument is crafted from a sterile disposable dermal curette with its top flattened using a needle holder(Figure 1). Termed the customized dermal curette, this device is a simple yet accurate tool for the precise excision of pigmented lesions within the nail matrix. Importantly, it offers versatility by accommodating different widths of pigmented lesions through the availability of various sizes of dermal curettes (Figure 2).

Histopathologically, we have found that the scalpel technique may lead to variable tissue removal, resulting in differences in tissue thickness, fragility, and completeness (Figure 3A). Conversely, the customized dermal curette consistently provides more accurate tissue excision, resulting in uniform tissue thickness and integrity (Figure 3B).

Practice Implications

Compared to the traditional scalpel, this modified tool offers distinct advantages. Specifically, the customized dermal curette provides enhanced maneuverability and control during the procedure, thereby improving the overall efficacy of the excision process. It also offers a more accurate approach to completely remove pigmented bands, which reduces the risk for postoperative recurrence. The simplicity, affordability, and ease of operation associated with customized dermal curettes holds promise as an effective alternative for tissue shaving, especially in cases involving narrow pigmented matrix lesions, thereby addressing a notable practice gap and enhancing patient care.

Practice Gap

Longitudinal melanonychia (LM) is characterized by the presence of a dark brown, longitudinal, pigmented band on the nail unit, often caused by melanocytic activation or melanocytic hyperplasia in the nail matrix. Distinguishing between benign and early malignant LM is crucial due to their similar clinical presentations.¹ Hence, surgical excision of the pigmented nail matrix followed by histopathologic examination is a common procedure aimed at managing LM and reducing the risk for delayed diagnosis of subungual melanoma.

Tangential matrix excision combined with the nail window technique has emerged as a common and favored surgical strategy for managing LM.² This method is highly valued for its ability to minimize the risk for severe permanent nail dystrophy and effectively reduce postsurgical pigmentation recurrence.

The procedure begins with the creation of a matrix window along the lateral edge of the pigmented band followed by 1 lateral incision carefully made on each side of the nail fold. This meticulous approach allows for the complete exposure of the pigmented lesion. Subsequently, the nail fold is separated from the dorsal surface of the nail plate to facilitate access to the pigmented nail matrix. Finally, the target pigmented area is excised using a scalpel.

Despite the recognized efficacy of this procedure, challenges do arise, particularly when the width of the pigmented matrix lesion is narrow. Holding the scalpel horizontally to ensure precise excision can prove to be demanding, leading to difficulty achieving complete lesion removal and obtaining the desired cosmetic outcomes. As such, there is a clear need to explore alternative tools that can effectively address these challenges while ensuring optimal surgical outcomes for patients with LM. We propose the use of the customized dermal curette.

The Technique

An improved curette tool is a practical solution for complete removal of the pigmented nail matrix. This enhanced instrument is crafted from a sterile disposable dermal curette with its top flattened using a needle holder(Figure 1). Termed the customized dermal curette, this device is a simple yet accurate tool for the precise excision of pigmented lesions within the nail matrix. Importantly, it offers versatility by accommodating different widths of pigmented lesions through the availability of various sizes of dermal curettes (Figure 2).

Histopathologically, we have found that the scalpel technique may lead to variable tissue removal, resulting in differences in tissue thickness, fragility, and completeness (Figure 3A). Conversely, the customized dermal curette consistently provides more accurate tissue excision, resulting in uniform tissue thickness and integrity (Figure 3B).

Practice Implications

Compared to the traditional scalpel, this modified tool offers distinct advantages. Specifically, the customized dermal curette provides enhanced maneuverability and control during the procedure, thereby improving the overall efficacy of the excision process. It also offers a more accurate approach to completely remove pigmented bands, which reduces the risk for postoperative recurrence. The simplicity, affordability, and ease of operation associated with customized dermal curettes holds promise as an effective alternative for tissue shaving, especially in cases involving narrow pigmented matrix lesions, thereby addressing a notable practice gap and enhancing patient care.

TOPLINE:

A study found significant associations between melasma and several comorbidities, including hypertension and hormonal contraception use, which were the most common.

METHODOLOGY:

• Melasma predominantly affects young women of color and often worsens in hyperestrogen states; understanding the association with comorbidities can improve surveillance and treatment strategies.
• Researchers evaluated 41,283 patients with melasma (mean age, 48.8 years; 93% women) from the TriNetX database and an equal number of matched control individuals.
• The main outcome was comorbidities including allergic rhinitis, atopic dermatitis, anticonvulsants, diabetes, hormonal contraceptives, hypothyroidism, hypertension, lupus, rosacea, skin cancer, and malignancy.

TAKEAWAY:

• Among those with melasma, 25% had hypertension and 24% used hormonal contraception, the two most commonly associated risk factors identified.
• Rosacea (odds ratio [OR], 5.1), atopic dermatitis (OR, 3.3), lupus (OR, 2.5), history of skin cancer (OR, 2.5), and history of internal malignancy (OR, 2.1) were associated with the highest risk of developing melasma (P < .01 for all).
• Asian (OR, 2.0; P < .01) and “other/unknown” races (OR, 1.7; P < .01) and Hispanic ethnicity (OR, 1.3; P < .01) were also significantly associated with melasma, while the odds were slightly lower among White, Black/African American, and “not Hispanic” groups (ORs, 0.8; P < .01 for all groups).

IN PRACTICE:

“Understanding the potential associations between these risk factors and melasma will better improve the management and monitoring of the most susceptible patients,” the authors wrote.

SOURCE:

The study, led by Ajay N. Sharma, MD, MBA, of the Department of Dermatology at the University of California, Irvine, was published online in Journal of Drugs in Dermatology.

LIMITATIONS:

The study limitations included the retrospective design, potential misclassification of diagnoses, and the inability to establish causality.

DISCLOSURES:

The study did not disclose any funding sources. The authors declared no conflicts of interest.

A version of this article first appeared on Medscape.com.

TOPLINE:

A study found significant associations between melasma and several comorbidities, including hypertension and hormonal contraception use, which were the most common.

METHODOLOGY:

• Melasma predominantly affects young women of color and often worsens in hyperestrogen states; understanding the association with comorbidities can improve surveillance and treatment strategies.
• Researchers evaluated 41,283 patients with melasma (mean age, 48.8 years; 93% women) from the TriNetX database and an equal number of matched control individuals.
• The main outcome was comorbidities including allergic rhinitis, atopic dermatitis, anticonvulsants, diabetes, hormonal contraceptives, hypothyroidism, hypertension, lupus, rosacea, skin cancer, and malignancy.

TAKEAWAY:

• Among those with melasma, 25% had hypertension and 24% used hormonal contraception, the two most commonly associated risk factors identified.
• Rosacea (odds ratio [OR], 5.1), atopic dermatitis (OR, 3.3), lupus (OR, 2.5), history of skin cancer (OR, 2.5), and history of internal malignancy (OR, 2.1) were associated with the highest risk of developing melasma (P < .01 for all).
• Asian (OR, 2.0; P < .01) and “other/unknown” races (OR, 1.7; P < .01) and Hispanic ethnicity (OR, 1.3; P < .01) were also significantly associated with melasma, while the odds were slightly lower among White, Black/African American, and “not Hispanic” groups (ORs, 0.8; P < .01 for all groups).

IN PRACTICE:

“Understanding the potential associations between these risk factors and melasma will better improve the management and monitoring of the most susceptible patients,” the authors wrote.

SOURCE:

The study, led by Ajay N. Sharma, MD, MBA, of the Department of Dermatology at the University of California, Irvine, was published online in Journal of Drugs in Dermatology.

LIMITATIONS:

The study limitations included the retrospective design, potential misclassification of diagnoses, and the inability to establish causality.

DISCLOSURES:

The study did not disclose any funding sources. The authors declared no conflicts of interest.

A version of this article first appeared on Medscape.com.

TOPLINE:

A study found significant associations between melasma and several comorbidities, including hypertension and hormonal contraception use, which were the most common.

METHODOLOGY:

• Melasma predominantly affects young women of color and often worsens in hyperestrogen states; understanding the association with comorbidities can improve surveillance and treatment strategies.
• Researchers evaluated 41,283 patients with melasma (mean age, 48.8 years; 93% women) from the TriNetX database and an equal number of matched control individuals.
• The main outcome was comorbidities including allergic rhinitis, atopic dermatitis, anticonvulsants, diabetes, hormonal contraceptives, hypothyroidism, hypertension, lupus, rosacea, skin cancer, and malignancy.

TAKEAWAY:

• Among those with melasma, 25% had hypertension and 24% used hormonal contraception, the two most commonly associated risk factors identified.
• Rosacea (odds ratio [OR], 5.1), atopic dermatitis (OR, 3.3), lupus (OR, 2.5), history of skin cancer (OR, 2.5), and history of internal malignancy (OR, 2.1) were associated with the highest risk of developing melasma (P < .01 for all).
• Asian (OR, 2.0; P < .01) and “other/unknown” races (OR, 1.7; P < .01) and Hispanic ethnicity (OR, 1.3; P < .01) were also significantly associated with melasma, while the odds were slightly lower among White, Black/African American, and “not Hispanic” groups (ORs, 0.8; P < .01 for all groups).

IN PRACTICE:

“Understanding the potential associations between these risk factors and melasma will better improve the management and monitoring of the most susceptible patients,” the authors wrote.

SOURCE:

The study, led by Ajay N. Sharma, MD, MBA, of the Department of Dermatology at the University of California, Irvine, was published online in Journal of Drugs in Dermatology.

LIMITATIONS:

The study limitations included the retrospective design, potential misclassification of diagnoses, and the inability to establish causality.

DISCLOSURES:

The study did not disclose any funding sources. The authors declared no conflicts of interest.

A version of this article first appeared on Medscape.com.

The Diagnosis: Prurigo Pigmentosa

A comprehensive metabolic panel collected from our patient 1 month earlier did not reveal any abnormalities. Serum methylmalonic acid and homocysteine were both elevated at 417 nmol/L (reference range [for those aged 2–59 years], 55–335 nmol/L) and 23 μmol/L (reference range, 5–15 μmol/L), respectively. Serum folate and 25-hydroxyvitamin D were low at 3.1 ng/mL (reference range, >4.8 ng/mL) and 5 ng/mL (reference range, 30–80 ng/mL), respectively. Vitamin B₁₂ was within reference range. Two 4-mm punch biopsies collected from the upper back showed spongiotic dermatitis.

Our patient’s histopathology results along with the rash distribution and medical history of anorexia increased suspicion for prurigo pigmentosa. A trial of oral doxycycline 100 mg twice daily for 2 weeks was prescribed. At 2-week follow-up, the patient’s mother revealed a history of ketosis in her daughter, solidifying the diagnosis. The patient was counseled on maintaining a healthy diet to prevent future breakouts. The patient’s rash resolved with diet modification and doxycycline; however, it recurred upon relapse of anorexia 4 months later.

Prurigo pigmentosa, originally identified in Japan by Nagashima et al,¹ is an uncommon recurrent inflammatory disorder predominantly observed in young adults of Asian descent. Subsequently, it was reported to occur among individuals from different ethnic backgrounds, indicating potential underdiagnosis or misdiagnosis in Western countries.² Although a direct pathogenic cause for prurigo pigmentosa has not been identified, a strong association has been linked to diet, specifically when ketosis is induced, such as in ketogenic diets and anorexia nervosa.^3-5 Other possible causes include sunlight exposure, clothing friction, and sweating.^1,5 The disease course is characterized by intermittent flares and spontaneous resolution, with recurrence in most cases. During the active phase, intensely pruritic, papulovesicular or urticarial papules are predominant and most often are localized to the upper body and torso, including the back, shoulders, neck, and chest.⁵ These flares can persist for several days but eventually subside, leaving behind a characteristic reticular pigmentation that can persist for months.⁵ First-line treatment often involves the use of tetracycline antibiotics, such as minocycline or doxycycline. ^2,4,5 Dapsone often is used with successful resolution. ⁶ Dietary modifications also have been found to be effective in treating prurigo pigmentosa, particularly in patients presenting with dietary insufficiency.^6,7 Increased carbohydrate intake has been shown to promote resolution. ⁶ Topical corticosteroids demonstrate limited efficacy in controlling flares.^6,8

Histopathology has been variably described, with initial findings reported as nonspecific.¹ However, it was later described as a distinct inflammatory disease of the skin with histologically distinct stages.^2,9 Early stages reveal scattered dermal, dermal papillary, and perivascular neutrophilic infiltration.⁹ The lesions then progress and become fully developed, at which point neutrophilic infiltration becomes more prominent, accompanied by the presence of intraepidermal neutrophils and spongiosis. As the lesions resolve, the infiltration transitions to lymphocytic, and lichenoid changes can sometimes be appreciated along with epidermal hyperplasia, hyperpigmentation, and dermal melanophages.⁹ Although these findings aid in the diagnosis of prurigo pigmentosa, a clinicopathologic correlation is necessary to establish a definitive diagnosis.

Because prurigo pigmentosa is rare, it often is misdiagnosed as another condition with a similar presentation and nonspecific biopsy findings.⁶ Allergic contact dermatitis is a common type IV delayed hypersensitivity reaction that manifests similar to prurigo pigmentosa with pruritus and a well-demarcated distribution¹⁰ that is related to the pattern of allergen exposure; in the case of allergic contact dermatitis related to textiles, a well-demarcated rash will appear in the distribution area of the associated clothing (eg, shirt, pants, shorts).¹¹ Development of allergy involves exposure and sensitization to an allergen, followed by subsequent re-exposure that results in cutaneous T-cell activation and inflammation. ¹⁰ Histopathology shows nonspecific spongiotic inflammation, and the gold standard for diagnosis is patch testing to identify the causative substance(s). Definitive treatment includes avoidance of identified allergies; however, if patients are unable to avoid the allergen or the cause is unknown, then corticosteroids, antihistamines, and/or calcineurin inhibitors are beneficial in controlling symptoms and flares.¹⁰

Pityrosporum folliculitis (also known as Malassezia folliculitis) is a fungal acneform condition that arises from overgrowth of normal skin flora Malassezia yeast,¹² which may be due to occlusion of follicles or disruption of the normal flora composition. Clinically, the manifestation may resemble prurigo pigmentosa in distribution and presence of intense pruritus. However, pustular lesions and involvement of the face can aid in differentiating Pityrosporum from prurigo pigmentosa, which can be confirmed via periodic acid–Schiff staining with numerous round yeasts within affected follicles. Oral antifungal therapy typically yields rapid improvement and resolution of symptoms.¹²

Urticaria and prurigo pigmentosa share similar clinical characteristics, with symptoms of intense pruritus and urticarial lesions on the trunk.^2,13 Urticaria is an IgEmediated type I hypersensitivity reaction characterized by wheals (ie, edematous red or pink lesions of variable size and shape that typically resolve spontaneously within 24–48 hours).¹³ Notably, urticaria will improve and in some cases completely resolve with antihistamines or anti-IgE antibody treatment, which may aid in distinguishing it from prurigo pigmentosa, as the latter typically exhibits limited response to such treatment.² Histopathology also can assist in the diagnosis by ruling out other causes of similar rash; however, biopsies are not routinely done unless other inflammatory conditions are of high suspicion.¹³

Bullous pemphigoid is an autoimmune, subepidermal, blistering dermatosis that is most common among the elderly.¹⁴ It is characterized by the presence of IgG antibodies that target BP180 and BP230, which initiate inflammatory cascades that lead to tissue damage and blister formation. It typically manifests as pruritic blistering eruptions, primarily on the limbs and trunk, but may involve the head, neck, or palmoplantar regions.¹⁴ Although blistering eruptions are the prodrome of the disease, some cases may present with nonspecific urticarial or eczematous lesions^14,15 that may resemble prurigo pigmentosa. The diagnosis is confirmed through direct immunofluorescence microscopy of biopsied lesions, which reveals IgG and/or C3 deposits along the dermoepidermal junction.14 Management of bullous pemphigoid involves timely initiation of dapsone or systemic corticosteroids, which have demonstrated high efficacy in controlling the disease and its associated symptoms.¹⁵

Our patient achieved a favorable response to diet modification and doxycycline therapy consistent with the diagnosis of prurigo pigmentosa. Unfortunately, the condition recurred following a relapse of anorexia. Management of prurigo pigmentosa necessitates not only accurate diagnosis but also addressing any underlying factors that may contribute to disease exacerbation. We anticipate the eating disorder will pose a major challenge in achieving long-term control of prurigo pigmentosa.

The Diagnosis: Prurigo Pigmentosa

A comprehensive metabolic panel collected from our patient 1 month earlier did not reveal any abnormalities. Serum methylmalonic acid and homocysteine were both elevated at 417 nmol/L (reference range [for those aged 2–59 years], 55–335 nmol/L) and 23 μmol/L (reference range, 5–15 μmol/L), respectively. Serum folate and 25-hydroxyvitamin D were low at 3.1 ng/mL (reference range, >4.8 ng/mL) and 5 ng/mL (reference range, 30–80 ng/mL), respectively. Vitamin B₁₂ was within reference range. Two 4-mm punch biopsies collected from the upper back showed spongiotic dermatitis.

Our patient’s histopathology results along with the rash distribution and medical history of anorexia increased suspicion for prurigo pigmentosa. A trial of oral doxycycline 100 mg twice daily for 2 weeks was prescribed. At 2-week follow-up, the patient’s mother revealed a history of ketosis in her daughter, solidifying the diagnosis. The patient was counseled on maintaining a healthy diet to prevent future breakouts. The patient’s rash resolved with diet modification and doxycycline; however, it recurred upon relapse of anorexia 4 months later.

Prurigo pigmentosa, originally identified in Japan by Nagashima et al,¹ is an uncommon recurrent inflammatory disorder predominantly observed in young adults of Asian descent. Subsequently, it was reported to occur among individuals from different ethnic backgrounds, indicating potential underdiagnosis or misdiagnosis in Western countries.² Although a direct pathogenic cause for prurigo pigmentosa has not been identified, a strong association has been linked to diet, specifically when ketosis is induced, such as in ketogenic diets and anorexia nervosa.^3-5 Other possible causes include sunlight exposure, clothing friction, and sweating.^1,5 The disease course is characterized by intermittent flares and spontaneous resolution, with recurrence in most cases. During the active phase, intensely pruritic, papulovesicular or urticarial papules are predominant and most often are localized to the upper body and torso, including the back, shoulders, neck, and chest.⁵ These flares can persist for several days but eventually subside, leaving behind a characteristic reticular pigmentation that can persist for months.⁵ First-line treatment often involves the use of tetracycline antibiotics, such as minocycline or doxycycline. ^2,4,5 Dapsone often is used with successful resolution. ⁶ Dietary modifications also have been found to be effective in treating prurigo pigmentosa, particularly in patients presenting with dietary insufficiency.^6,7 Increased carbohydrate intake has been shown to promote resolution. ⁶ Topical corticosteroids demonstrate limited efficacy in controlling flares.^6,8

Histopathology has been variably described, with initial findings reported as nonspecific.¹ However, it was later described as a distinct inflammatory disease of the skin with histologically distinct stages.^2,9 Early stages reveal scattered dermal, dermal papillary, and perivascular neutrophilic infiltration.⁹ The lesions then progress and become fully developed, at which point neutrophilic infiltration becomes more prominent, accompanied by the presence of intraepidermal neutrophils and spongiosis. As the lesions resolve, the infiltration transitions to lymphocytic, and lichenoid changes can sometimes be appreciated along with epidermal hyperplasia, hyperpigmentation, and dermal melanophages.⁹ Although these findings aid in the diagnosis of prurigo pigmentosa, a clinicopathologic correlation is necessary to establish a definitive diagnosis.

Because prurigo pigmentosa is rare, it often is misdiagnosed as another condition with a similar presentation and nonspecific biopsy findings.⁶ Allergic contact dermatitis is a common type IV delayed hypersensitivity reaction that manifests similar to prurigo pigmentosa with pruritus and a well-demarcated distribution¹⁰ that is related to the pattern of allergen exposure; in the case of allergic contact dermatitis related to textiles, a well-demarcated rash will appear in the distribution area of the associated clothing (eg, shirt, pants, shorts).¹¹ Development of allergy involves exposure and sensitization to an allergen, followed by subsequent re-exposure that results in cutaneous T-cell activation and inflammation. ¹⁰ Histopathology shows nonspecific spongiotic inflammation, and the gold standard for diagnosis is patch testing to identify the causative substance(s). Definitive treatment includes avoidance of identified allergies; however, if patients are unable to avoid the allergen or the cause is unknown, then corticosteroids, antihistamines, and/or calcineurin inhibitors are beneficial in controlling symptoms and flares.¹⁰

Pityrosporum folliculitis (also known as Malassezia folliculitis) is a fungal acneform condition that arises from overgrowth of normal skin flora Malassezia yeast,¹² which may be due to occlusion of follicles or disruption of the normal flora composition. Clinically, the manifestation may resemble prurigo pigmentosa in distribution and presence of intense pruritus. However, pustular lesions and involvement of the face can aid in differentiating Pityrosporum from prurigo pigmentosa, which can be confirmed via periodic acid–Schiff staining with numerous round yeasts within affected follicles. Oral antifungal therapy typically yields rapid improvement and resolution of symptoms.¹²

Urticaria and prurigo pigmentosa share similar clinical characteristics, with symptoms of intense pruritus and urticarial lesions on the trunk.^2,13 Urticaria is an IgEmediated type I hypersensitivity reaction characterized by wheals (ie, edematous red or pink lesions of variable size and shape that typically resolve spontaneously within 24–48 hours).¹³ Notably, urticaria will improve and in some cases completely resolve with antihistamines or anti-IgE antibody treatment, which may aid in distinguishing it from prurigo pigmentosa, as the latter typically exhibits limited response to such treatment.² Histopathology also can assist in the diagnosis by ruling out other causes of similar rash; however, biopsies are not routinely done unless other inflammatory conditions are of high suspicion.¹³

Bullous pemphigoid is an autoimmune, subepidermal, blistering dermatosis that is most common among the elderly.¹⁴ It is characterized by the presence of IgG antibodies that target BP180 and BP230, which initiate inflammatory cascades that lead to tissue damage and blister formation. It typically manifests as pruritic blistering eruptions, primarily on the limbs and trunk, but may involve the head, neck, or palmoplantar regions.¹⁴ Although blistering eruptions are the prodrome of the disease, some cases may present with nonspecific urticarial or eczematous lesions^14,15 that may resemble prurigo pigmentosa. The diagnosis is confirmed through direct immunofluorescence microscopy of biopsied lesions, which reveals IgG and/or C3 deposits along the dermoepidermal junction.14 Management of bullous pemphigoid involves timely initiation of dapsone or systemic corticosteroids, which have demonstrated high efficacy in controlling the disease and its associated symptoms.¹⁵

Our patient achieved a favorable response to diet modification and doxycycline therapy consistent with the diagnosis of prurigo pigmentosa. Unfortunately, the condition recurred following a relapse of anorexia. Management of prurigo pigmentosa necessitates not only accurate diagnosis but also addressing any underlying factors that may contribute to disease exacerbation. We anticipate the eating disorder will pose a major challenge in achieving long-term control of prurigo pigmentosa.

The Diagnosis: Prurigo Pigmentosa

A comprehensive metabolic panel collected from our patient 1 month earlier did not reveal any abnormalities. Serum methylmalonic acid and homocysteine were both elevated at 417 nmol/L (reference range [for those aged 2–59 years], 55–335 nmol/L) and 23 μmol/L (reference range, 5–15 μmol/L), respectively. Serum folate and 25-hydroxyvitamin D were low at 3.1 ng/mL (reference range, >4.8 ng/mL) and 5 ng/mL (reference range, 30–80 ng/mL), respectively. Vitamin B₁₂ was within reference range. Two 4-mm punch biopsies collected from the upper back showed spongiotic dermatitis.

Our patient’s histopathology results along with the rash distribution and medical history of anorexia increased suspicion for prurigo pigmentosa. A trial of oral doxycycline 100 mg twice daily for 2 weeks was prescribed. At 2-week follow-up, the patient’s mother revealed a history of ketosis in her daughter, solidifying the diagnosis. The patient was counseled on maintaining a healthy diet to prevent future breakouts. The patient’s rash resolved with diet modification and doxycycline; however, it recurred upon relapse of anorexia 4 months later.

Prurigo pigmentosa, originally identified in Japan by Nagashima et al,¹ is an uncommon recurrent inflammatory disorder predominantly observed in young adults of Asian descent. Subsequently, it was reported to occur among individuals from different ethnic backgrounds, indicating potential underdiagnosis or misdiagnosis in Western countries.² Although a direct pathogenic cause for prurigo pigmentosa has not been identified, a strong association has been linked to diet, specifically when ketosis is induced, such as in ketogenic diets and anorexia nervosa.^3-5 Other possible causes include sunlight exposure, clothing friction, and sweating.^1,5 The disease course is characterized by intermittent flares and spontaneous resolution, with recurrence in most cases. During the active phase, intensely pruritic, papulovesicular or urticarial papules are predominant and most often are localized to the upper body and torso, including the back, shoulders, neck, and chest.⁵ These flares can persist for several days but eventually subside, leaving behind a characteristic reticular pigmentation that can persist for months.⁵ First-line treatment often involves the use of tetracycline antibiotics, such as minocycline or doxycycline. ^2,4,5 Dapsone often is used with successful resolution. ⁶ Dietary modifications also have been found to be effective in treating prurigo pigmentosa, particularly in patients presenting with dietary insufficiency.^6,7 Increased carbohydrate intake has been shown to promote resolution. ⁶ Topical corticosteroids demonstrate limited efficacy in controlling flares.^6,8

Histopathology has been variably described, with initial findings reported as nonspecific.¹ However, it was later described as a distinct inflammatory disease of the skin with histologically distinct stages.^2,9 Early stages reveal scattered dermal, dermal papillary, and perivascular neutrophilic infiltration.⁹ The lesions then progress and become fully developed, at which point neutrophilic infiltration becomes more prominent, accompanied by the presence of intraepidermal neutrophils and spongiosis. As the lesions resolve, the infiltration transitions to lymphocytic, and lichenoid changes can sometimes be appreciated along with epidermal hyperplasia, hyperpigmentation, and dermal melanophages.⁹ Although these findings aid in the diagnosis of prurigo pigmentosa, a clinicopathologic correlation is necessary to establish a definitive diagnosis.

Because prurigo pigmentosa is rare, it often is misdiagnosed as another condition with a similar presentation and nonspecific biopsy findings.⁶ Allergic contact dermatitis is a common type IV delayed hypersensitivity reaction that manifests similar to prurigo pigmentosa with pruritus and a well-demarcated distribution¹⁰ that is related to the pattern of allergen exposure; in the case of allergic contact dermatitis related to textiles, a well-demarcated rash will appear in the distribution area of the associated clothing (eg, shirt, pants, shorts).¹¹ Development of allergy involves exposure and sensitization to an allergen, followed by subsequent re-exposure that results in cutaneous T-cell activation and inflammation. ¹⁰ Histopathology shows nonspecific spongiotic inflammation, and the gold standard for diagnosis is patch testing to identify the causative substance(s). Definitive treatment includes avoidance of identified allergies; however, if patients are unable to avoid the allergen or the cause is unknown, then corticosteroids, antihistamines, and/or calcineurin inhibitors are beneficial in controlling symptoms and flares.¹⁰

Pityrosporum folliculitis (also known as Malassezia folliculitis) is a fungal acneform condition that arises from overgrowth of normal skin flora Malassezia yeast,¹² which may be due to occlusion of follicles or disruption of the normal flora composition. Clinically, the manifestation may resemble prurigo pigmentosa in distribution and presence of intense pruritus. However, pustular lesions and involvement of the face can aid in differentiating Pityrosporum from prurigo pigmentosa, which can be confirmed via periodic acid–Schiff staining with numerous round yeasts within affected follicles. Oral antifungal therapy typically yields rapid improvement and resolution of symptoms.¹²

Urticaria and prurigo pigmentosa share similar clinical characteristics, with symptoms of intense pruritus and urticarial lesions on the trunk.^2,13 Urticaria is an IgEmediated type I hypersensitivity reaction characterized by wheals (ie, edematous red or pink lesions of variable size and shape that typically resolve spontaneously within 24–48 hours).¹³ Notably, urticaria will improve and in some cases completely resolve with antihistamines or anti-IgE antibody treatment, which may aid in distinguishing it from prurigo pigmentosa, as the latter typically exhibits limited response to such treatment.² Histopathology also can assist in the diagnosis by ruling out other causes of similar rash; however, biopsies are not routinely done unless other inflammatory conditions are of high suspicion.¹³

Bullous pemphigoid is an autoimmune, subepidermal, blistering dermatosis that is most common among the elderly.¹⁴ It is characterized by the presence of IgG antibodies that target BP180 and BP230, which initiate inflammatory cascades that lead to tissue damage and blister formation. It typically manifests as pruritic blistering eruptions, primarily on the limbs and trunk, but may involve the head, neck, or palmoplantar regions.¹⁴ Although blistering eruptions are the prodrome of the disease, some cases may present with nonspecific urticarial or eczematous lesions^14,15 that may resemble prurigo pigmentosa. The diagnosis is confirmed through direct immunofluorescence microscopy of biopsied lesions, which reveals IgG and/or C3 deposits along the dermoepidermal junction.14 Management of bullous pemphigoid involves timely initiation of dapsone or systemic corticosteroids, which have demonstrated high efficacy in controlling the disease and its associated symptoms.¹⁵

Our patient achieved a favorable response to diet modification and doxycycline therapy consistent with the diagnosis of prurigo pigmentosa. Unfortunately, the condition recurred following a relapse of anorexia. Management of prurigo pigmentosa necessitates not only accurate diagnosis but also addressing any underlying factors that may contribute to disease exacerbation. We anticipate the eating disorder will pose a major challenge in achieving long-term control of prurigo pigmentosa.

Adolescents with nonsegmental vitiligo who applied topical ruxolitinib, 1.5% cream were more likely than adults to achieve complete repigmentation, a post hoc analysis of pivotal clinical trial data showed. 

“We consider repigmenting vitiligo a two-step process, where the overactive immune system needs to be calmed down and then the melanocytes need to repopulate to the white areas,” one of the study investigators, David Rosmarin, MD, chair of the Department of Dermatology at Indiana University School of Medicine, Indianapolis, said in an interview in advance of the annual meeting of the Society for Pediatric Dermatology, where the study results were presented during a poster session. “In younger patients, it may be that the melanocytes are more rapidly repigmenting the patches, which is why we see this effect.”

Ruxolitinib, 1.5% cream (Opzelura) is a Janus kinase inhibitor approved for the treatment of nonsegmental vitiligo in patients 12 years of age and older. Dr. Rosmarin and colleagues sought to evaluate differences in rates of complete or near-complete repigmentation and repigmentation by body region between adolescents 12-17 years of age and adults 18 years of age and older who applied ruxolitinib cream twice daily. The researchers evaluated patients who were initially randomized to ruxolitinib cream, 1.5% in the pivotal TRuE-V1 and TRuE-V2 studies and applied it for up to 104 weeks. Complete facial improvement was defined as 100% improvement on the Facial Vitiligo Area Scoring Index (F-VASI 100) from baseline, and near-total improvement was categorized as a ≥ 75% or ≥ 90% improvement from baseline on the Total body VASI (T-VASI). Responses for each of six body regions, excluding the face, were assessed by the proportion of patients who achieved at least a 50% improvement from baseline on the T-VASI.

Compared with adults, a greater proportion of adolescents achieved F-VASI 100 at week 24 (5.7% [3/53] vs 2.9% [10/341], respectively), but there were no differences between the two groups at week 52 (8.0% [4/50] vs 8.0% [24/300]). Response rates were greater among adolescents vs adults for T-VASI 75 at weeks 24 (13.2% [7/53] vs 5.6% [19/341]) and 52 (22.0% [11/50] vs 20.3% [61/300]), as well as T-VASI 90 at weeks 24 (3.8% [2/53] vs 0.3% [1/341]) and 52 (12.0% [6/50] vs 4.0% [12/300]).

The researchers observed that VASI 50 responses by body region were generally similar between adolescents and adults, but a greater proportion of adolescents achieved a VASI 50 in lower extremities (67.3% [33/49] vs 51.8% [118/228]) and feet (37.5% [12/32] vs 27.9% [51/183]) at week 52.

FG Trade/Getty Images

“Adolescents repigmented more rapidly than adults, so that at 24 weeks, more teens had complete facial repigmentation and T-VASI 75 and T-VASI 90 results,” Dr. Rosmarin said. “With continued use of ruxolitinib cream, both more adults and adolescents achieved greater repigmentation.” He acknowledged certain limitations of the study, including the fact that it was only vehicle controlled up through 24 weeks and that, after week 52, there were fewer patients who completed the long-term extension.

“The take-home message is that ruxolitinib cream can effectively and safely help many patients repigment, including adolescents,” he said.

The study was funded by topical ruxolitinib manufacturer Incyte. Dr. Rosmarin disclosed that he has consulted, spoken for, or conducted trials for AbbVie, Abcuro, Almirall, AltruBio, Amgen, Arena, Astria, Boehringer Ingelheim, Bristol Meyers Squibb, Celgene, Concert, CSL Behring, Dermavant Sciences, Dermira, Galderma, Incyte, Janssen, Kyowa Kirin, Lilly, Merck, Nektar, Novartis, Pfizer, RAPT, Regeneron, Recludix Pharma, Revolo Biotherapeutics, Sanofi, Sun Pharmaceuticals, UCB, Viela Bio, and Zura.

A version of this article first appeared on Medscape.com.

Adolescents with nonsegmental vitiligo who applied topical ruxolitinib, 1.5% cream were more likely than adults to achieve complete repigmentation, a post hoc analysis of pivotal clinical trial data showed. 

“We consider repigmenting vitiligo a two-step process, where the overactive immune system needs to be calmed down and then the melanocytes need to repopulate to the white areas,” one of the study investigators, David Rosmarin, MD, chair of the Department of Dermatology at Indiana University School of Medicine, Indianapolis, said in an interview in advance of the annual meeting of the Society for Pediatric Dermatology, where the study results were presented during a poster session. “In younger patients, it may be that the melanocytes are more rapidly repigmenting the patches, which is why we see this effect.”

Ruxolitinib, 1.5% cream (Opzelura) is a Janus kinase inhibitor approved for the treatment of nonsegmental vitiligo in patients 12 years of age and older. Dr. Rosmarin and colleagues sought to evaluate differences in rates of complete or near-complete repigmentation and repigmentation by body region between adolescents 12-17 years of age and adults 18 years of age and older who applied ruxolitinib cream twice daily. The researchers evaluated patients who were initially randomized to ruxolitinib cream, 1.5% in the pivotal TRuE-V1 and TRuE-V2 studies and applied it for up to 104 weeks. Complete facial improvement was defined as 100% improvement on the Facial Vitiligo Area Scoring Index (F-VASI 100) from baseline, and near-total improvement was categorized as a ≥ 75% or ≥ 90% improvement from baseline on the Total body VASI (T-VASI). Responses for each of six body regions, excluding the face, were assessed by the proportion of patients who achieved at least a 50% improvement from baseline on the T-VASI.

Compared with adults, a greater proportion of adolescents achieved F-VASI 100 at week 24 (5.7% [3/53] vs 2.9% [10/341], respectively), but there were no differences between the two groups at week 52 (8.0% [4/50] vs 8.0% [24/300]). Response rates were greater among adolescents vs adults for T-VASI 75 at weeks 24 (13.2% [7/53] vs 5.6% [19/341]) and 52 (22.0% [11/50] vs 20.3% [61/300]), as well as T-VASI 90 at weeks 24 (3.8% [2/53] vs 0.3% [1/341]) and 52 (12.0% [6/50] vs 4.0% [12/300]).

The researchers observed that VASI 50 responses by body region were generally similar between adolescents and adults, but a greater proportion of adolescents achieved a VASI 50 in lower extremities (67.3% [33/49] vs 51.8% [118/228]) and feet (37.5% [12/32] vs 27.9% [51/183]) at week 52.

FG Trade/Getty Images

“Adolescents repigmented more rapidly than adults, so that at 24 weeks, more teens had complete facial repigmentation and T-VASI 75 and T-VASI 90 results,” Dr. Rosmarin said. “With continued use of ruxolitinib cream, both more adults and adolescents achieved greater repigmentation.” He acknowledged certain limitations of the study, including the fact that it was only vehicle controlled up through 24 weeks and that, after week 52, there were fewer patients who completed the long-term extension.

“The take-home message is that ruxolitinib cream can effectively and safely help many patients repigment, including adolescents,” he said.

The study was funded by topical ruxolitinib manufacturer Incyte. Dr. Rosmarin disclosed that he has consulted, spoken for, or conducted trials for AbbVie, Abcuro, Almirall, AltruBio, Amgen, Arena, Astria, Boehringer Ingelheim, Bristol Meyers Squibb, Celgene, Concert, CSL Behring, Dermavant Sciences, Dermira, Galderma, Incyte, Janssen, Kyowa Kirin, Lilly, Merck, Nektar, Novartis, Pfizer, RAPT, Regeneron, Recludix Pharma, Revolo Biotherapeutics, Sanofi, Sun Pharmaceuticals, UCB, Viela Bio, and Zura.

A version of this article first appeared on Medscape.com.

Adolescents with nonsegmental vitiligo who applied topical ruxolitinib, 1.5% cream were more likely than adults to achieve complete repigmentation, a post hoc analysis of pivotal clinical trial data showed. 

“We consider repigmenting vitiligo a two-step process, where the overactive immune system needs to be calmed down and then the melanocytes need to repopulate to the white areas,” one of the study investigators, David Rosmarin, MD, chair of the Department of Dermatology at Indiana University School of Medicine, Indianapolis, said in an interview in advance of the annual meeting of the Society for Pediatric Dermatology, where the study results were presented during a poster session. “In younger patients, it may be that the melanocytes are more rapidly repigmenting the patches, which is why we see this effect.”

Ruxolitinib, 1.5% cream (Opzelura) is a Janus kinase inhibitor approved for the treatment of nonsegmental vitiligo in patients 12 years of age and older. Dr. Rosmarin and colleagues sought to evaluate differences in rates of complete or near-complete repigmentation and repigmentation by body region between adolescents 12-17 years of age and adults 18 years of age and older who applied ruxolitinib cream twice daily. The researchers evaluated patients who were initially randomized to ruxolitinib cream, 1.5% in the pivotal TRuE-V1 and TRuE-V2 studies and applied it for up to 104 weeks. Complete facial improvement was defined as 100% improvement on the Facial Vitiligo Area Scoring Index (F-VASI 100) from baseline, and near-total improvement was categorized as a ≥ 75% or ≥ 90% improvement from baseline on the Total body VASI (T-VASI). Responses for each of six body regions, excluding the face, were assessed by the proportion of patients who achieved at least a 50% improvement from baseline on the T-VASI.

Compared with adults, a greater proportion of adolescents achieved F-VASI 100 at week 24 (5.7% [3/53] vs 2.9% [10/341], respectively), but there were no differences between the two groups at week 52 (8.0% [4/50] vs 8.0% [24/300]). Response rates were greater among adolescents vs adults for T-VASI 75 at weeks 24 (13.2% [7/53] vs 5.6% [19/341]) and 52 (22.0% [11/50] vs 20.3% [61/300]), as well as T-VASI 90 at weeks 24 (3.8% [2/53] vs 0.3% [1/341]) and 52 (12.0% [6/50] vs 4.0% [12/300]).

The researchers observed that VASI 50 responses by body region were generally similar between adolescents and adults, but a greater proportion of adolescents achieved a VASI 50 in lower extremities (67.3% [33/49] vs 51.8% [118/228]) and feet (37.5% [12/32] vs 27.9% [51/183]) at week 52.

FG Trade/Getty Images

“Adolescents repigmented more rapidly than adults, so that at 24 weeks, more teens had complete facial repigmentation and T-VASI 75 and T-VASI 90 results,” Dr. Rosmarin said. “With continued use of ruxolitinib cream, both more adults and adolescents achieved greater repigmentation.” He acknowledged certain limitations of the study, including the fact that it was only vehicle controlled up through 24 weeks and that, after week 52, there were fewer patients who completed the long-term extension.

“The take-home message is that ruxolitinib cream can effectively and safely help many patients repigment, including adolescents,” he said.

The study was funded by topical ruxolitinib manufacturer Incyte. Dr. Rosmarin disclosed that he has consulted, spoken for, or conducted trials for AbbVie, Abcuro, Almirall, AltruBio, Amgen, Arena, Astria, Boehringer Ingelheim, Bristol Meyers Squibb, Celgene, Concert, CSL Behring, Dermavant Sciences, Dermira, Galderma, Incyte, Janssen, Kyowa Kirin, Lilly, Merck, Nektar, Novartis, Pfizer, RAPT, Regeneron, Recludix Pharma, Revolo Biotherapeutics, Sanofi, Sun Pharmaceuticals, UCB, Viela Bio, and Zura.

A version of this article first appeared on Medscape.com.

TOPLINE:

A meta-analysis showed that the use of oral tranexamic acid along with the standard triple combination cream (TCC) reduces melasma severity and recurrence in patients with melasma, without increasing toxicity.

METHODOLOGY:

• Current treatments for melasma focus on inducing remission and preventing relapse. Tranexamic acid, an antifibrinolytic drug, has shown promise in recent studies, but its optimal use, either alone or as an adjunct to TCC, remains unclear.
• Researchers conducted a meta-analysis of four randomized controlled trials patients that compared oral tranexamic acid plus TCC (hydroquinone, retinoic acid, and hydrocortisone) and TCC alone in 480 patients with melasma, divided almost evenly into the two treatment groups.
• The main outcome was the change in the Melasma Severity Area Index (MASI) score and recurrence rate from baseline.

TAKEAWAY:

• Patients treated with oral tranexamic acid plus TCC showed a greater reduction in MASI scores compared with those who received TCC alone (mean difference, −3.10; P = .03).
• The recurrence rate of melasma was significantly lower in the tranexamic acid plus TCC group (risk ratio [RR], 0.28; P < .001).
• There was no significant difference in the incidences of erythema (RR, 0.63; P = .147) and burning (RR, 0.59; P = .131).

IN PRACTICE:

“Evidence indicates that oral tranexamic acid confers clinical benefits, contributing to the enhancement of treatment outcomes in melasma when used in conjunction with TCC therapy,” and results are promising with regards to minimizing recurrence, the authors concluded.

SOURCE:

The study was led by Ocílio Ribeiro Gonçalves, MS, of the Federal University of Piauí, Teresina, Brazil, and was published online on June 8, 2024, in Clinical and Experimental Dermatology.

LIMITATIONS:

There was heterogeneity across studies, including different methods of administration, treatment protocols (including dosage), and timing of treatment.

DISCLOSURES:

The study reported receiving no funding. The authors declared no conflicts of interest.
 

A version of this article appeared on Medscape.com.

TOPLINE:

A meta-analysis showed that the use of oral tranexamic acid along with the standard triple combination cream (TCC) reduces melasma severity and recurrence in patients with melasma, without increasing toxicity.

METHODOLOGY:

• Current treatments for melasma focus on inducing remission and preventing relapse. Tranexamic acid, an antifibrinolytic drug, has shown promise in recent studies, but its optimal use, either alone or as an adjunct to TCC, remains unclear.
• Researchers conducted a meta-analysis of four randomized controlled trials patients that compared oral tranexamic acid plus TCC (hydroquinone, retinoic acid, and hydrocortisone) and TCC alone in 480 patients with melasma, divided almost evenly into the two treatment groups.
• The main outcome was the change in the Melasma Severity Area Index (MASI) score and recurrence rate from baseline.

TAKEAWAY:

• Patients treated with oral tranexamic acid plus TCC showed a greater reduction in MASI scores compared with those who received TCC alone (mean difference, −3.10; P = .03).
• The recurrence rate of melasma was significantly lower in the tranexamic acid plus TCC group (risk ratio [RR], 0.28; P < .001).
• There was no significant difference in the incidences of erythema (RR, 0.63; P = .147) and burning (RR, 0.59; P = .131).

IN PRACTICE:

“Evidence indicates that oral tranexamic acid confers clinical benefits, contributing to the enhancement of treatment outcomes in melasma when used in conjunction with TCC therapy,” and results are promising with regards to minimizing recurrence, the authors concluded.

SOURCE:

The study was led by Ocílio Ribeiro Gonçalves, MS, of the Federal University of Piauí, Teresina, Brazil, and was published online on June 8, 2024, in Clinical and Experimental Dermatology.

LIMITATIONS:

There was heterogeneity across studies, including different methods of administration, treatment protocols (including dosage), and timing of treatment.

DISCLOSURES:

The study reported receiving no funding. The authors declared no conflicts of interest.
 

A version of this article appeared on Medscape.com.

TOPLINE:

A meta-analysis showed that the use of oral tranexamic acid along with the standard triple combination cream (TCC) reduces melasma severity and recurrence in patients with melasma, without increasing toxicity.

METHODOLOGY:

• Current treatments for melasma focus on inducing remission and preventing relapse. Tranexamic acid, an antifibrinolytic drug, has shown promise in recent studies, but its optimal use, either alone or as an adjunct to TCC, remains unclear.
• Researchers conducted a meta-analysis of four randomized controlled trials patients that compared oral tranexamic acid plus TCC (hydroquinone, retinoic acid, and hydrocortisone) and TCC alone in 480 patients with melasma, divided almost evenly into the two treatment groups.
• The main outcome was the change in the Melasma Severity Area Index (MASI) score and recurrence rate from baseline.

TAKEAWAY:

• Patients treated with oral tranexamic acid plus TCC showed a greater reduction in MASI scores compared with those who received TCC alone (mean difference, −3.10; P = .03).
• The recurrence rate of melasma was significantly lower in the tranexamic acid plus TCC group (risk ratio [RR], 0.28; P < .001).
• There was no significant difference in the incidences of erythema (RR, 0.63; P = .147) and burning (RR, 0.59; P = .131).

IN PRACTICE:

“Evidence indicates that oral tranexamic acid confers clinical benefits, contributing to the enhancement of treatment outcomes in melasma when used in conjunction with TCC therapy,” and results are promising with regards to minimizing recurrence, the authors concluded.

SOURCE:

The study was led by Ocílio Ribeiro Gonçalves, MS, of the Federal University of Piauí, Teresina, Brazil, and was published online on June 8, 2024, in Clinical and Experimental Dermatology.

LIMITATIONS:

There was heterogeneity across studies, including different methods of administration, treatment protocols (including dosage), and timing of treatment.

DISCLOSURES:

The study reported receiving no funding. The authors declared no conflicts of interest.
 

A version of this article appeared on Medscape.com.

CHICAGO —The use of kratom, an opioid-like supplement widely available over the counter at convenience stores, smoke shops, and online, is resulting in emerging cases of hyperpigmentation, most often on the face and hands.

“This is something we will see more and more,” Heather Woolery-Lloyd, MD, director of the Skin of Color Division at the University of Miami Department of Dermatology, said at the Pigmentary Disorders Exchange Symposium. The key marker of this hyperpigmentation, she said, is that “it’s strongly photoaccentuated,” affecting areas exposed to the sun — but it also tends to spare the knuckles on patients’ hands.
 

Used Like an Opioid, But It’s Not Regulated

Kratom is a plant common in southeast Asia and is used as an analgesic. It’s marketed as a “legal opioid” or “legal high” and is sold in 2- or 3-ounce containers of extract or sold as a powder, Dr. Woolery-Lloyd said. The leaves may be boiled into a tea, smoked, chewed, or put into capsules, according to a case report published in February in the Journal of Integrative Dermatology. It is used worldwide and is not regulated in the United States.

“Many of our patients think kratom is a safe, herbal supplement” but often don’t know it can have several side effects and can be addictive, Dr. Woolery-Lloyd said. Its popularity is increasing as reflected by the number of posts related to kratom on social media platforms.

In the February case report, Shaina Patel, BA, and Nathaniel Phelan, MD, from Kansas City University, Kansas City, Missouri, wrote that side effects of kratom include drowsiness, tachycardia, vomiting, respiratory depression, and cardiac arrest, in addition to confusion and hallucinations.

Kratom also has many different effects on the psyche, Dr. Woolery-Lloyd said at the meeting. At low doses, it blocks the reuptake of norepinephrine, serotonin, and dopamine, producing a motivational effect, and at high doses, it creates an analgesic, calming effect. And people who chronically consume high doses of kratom may be susceptible to hyperpigmentation.

Kratom-associated hyperpigmentation should be considered as a diagnosis when evaluating patients for other drug-associated pigmentary disorders, “especially if pigment is photodistributed,” she said. “If you see new-onset hyperpigmentation or onset over several months and it’s very photoaccentuated, definitely ask about use of kratom.”
 

Case Reports Show Patterns of Presentation

A 2022 report from Landon R. Powell, BS, with the department of biology, Whitworth University in Spokane, Washington, and coauthors, published in JAAD Case Reports, noted that kratom use in the United States has increased dramatically. “As measured by call reports to the United States National Poison Data System, in 2011, there were 11 reported kratom exposures, and in the first 7 months of 2018, there were 357 reported exposures,” they wrote.

An estimated 1.7 million Americans aged ≥ 12 years said they had used kratom in the previous year, according to the Substance Abuse and Mental Health Services Administration 2021 National Survey on Drug Use and Health.

In the case report, Mr. Powell and coauthors described a 54-year-old White male patient who had been using kratom for the previous four to five years to reduce opioid use. During this period, he consumed kratom powder mixed with orange juice three to four times a day. He presented with “diffuse hyperpigmented patches on his arms and face in a photodistributed manner, with notable sparing of the knuckles on both hands.”
 

Dark Gray-Blue Skin

In the more recent case report, Ms. Patel and Dr. Phelan described a 30-year-old White male patient who presented with dark gray-blue skin coloring on his cheeks, back of his neck, and the backs of his hands and forearms. He had no other medical conditions and did not take any medications or supplements that cause hyperpigmentation while using kratom.

The patient had been taking kratom for years in the wake of an opioid addiction following medications for a high school injury. He developed an opioid use disorder and tried to replace his pain medications with kratom.

“The patient stopped using kratom in May 2022, but the discoloration remains. It has not regressed in the following 16 months after discontinuing kratom use,” the authors wrote, noting that “whether or not the hyperpigmentation is able to regress is unknown.”

Dr. Woolery-Lloyd is a consultant for AbbVie, Incyte, Johnson & Johnson Consumer, LivDerm, and L’Oreal; a speaker for Eli Lilly, Incyte, L’Oreal, and Ortho Dermatologics; and a researcher/investigator for AbbVie, Allergan, Eirion Therapeutics, Galderma, Pfizer, Sanofi, and Vyne Therapeutics.
 

According to an information page on kratom on the Food and Drug Administration website, health care professionals and consumers can report adverse reactions associated with kratom to the FDA’s MedWatch program.

A version of this article appeared on Medscape.com.

CHICAGO —The use of kratom, an opioid-like supplement widely available over the counter at convenience stores, smoke shops, and online, is resulting in emerging cases of hyperpigmentation, most often on the face and hands.

“This is something we will see more and more,” Heather Woolery-Lloyd, MD, director of the Skin of Color Division at the University of Miami Department of Dermatology, said at the Pigmentary Disorders Exchange Symposium. The key marker of this hyperpigmentation, she said, is that “it’s strongly photoaccentuated,” affecting areas exposed to the sun — but it also tends to spare the knuckles on patients’ hands.
 

Used Like an Opioid, But It’s Not Regulated

Kratom is a plant common in southeast Asia and is used as an analgesic. It’s marketed as a “legal opioid” or “legal high” and is sold in 2- or 3-ounce containers of extract or sold as a powder, Dr. Woolery-Lloyd said. The leaves may be boiled into a tea, smoked, chewed, or put into capsules, according to a case report published in February in the Journal of Integrative Dermatology. It is used worldwide and is not regulated in the United States.

“Many of our patients think kratom is a safe, herbal supplement” but often don’t know it can have several side effects and can be addictive, Dr. Woolery-Lloyd said. Its popularity is increasing as reflected by the number of posts related to kratom on social media platforms.

In the February case report, Shaina Patel, BA, and Nathaniel Phelan, MD, from Kansas City University, Kansas City, Missouri, wrote that side effects of kratom include drowsiness, tachycardia, vomiting, respiratory depression, and cardiac arrest, in addition to confusion and hallucinations.

Kratom also has many different effects on the psyche, Dr. Woolery-Lloyd said at the meeting. At low doses, it blocks the reuptake of norepinephrine, serotonin, and dopamine, producing a motivational effect, and at high doses, it creates an analgesic, calming effect. And people who chronically consume high doses of kratom may be susceptible to hyperpigmentation.

Kratom-associated hyperpigmentation should be considered as a diagnosis when evaluating patients for other drug-associated pigmentary disorders, “especially if pigment is photodistributed,” she said. “If you see new-onset hyperpigmentation or onset over several months and it’s very photoaccentuated, definitely ask about use of kratom.”
 

Case Reports Show Patterns of Presentation

A 2022 report from Landon R. Powell, BS, with the department of biology, Whitworth University in Spokane, Washington, and coauthors, published in JAAD Case Reports, noted that kratom use in the United States has increased dramatically. “As measured by call reports to the United States National Poison Data System, in 2011, there were 11 reported kratom exposures, and in the first 7 months of 2018, there were 357 reported exposures,” they wrote.

An estimated 1.7 million Americans aged ≥ 12 years said they had used kratom in the previous year, according to the Substance Abuse and Mental Health Services Administration 2021 National Survey on Drug Use and Health.

In the case report, Mr. Powell and coauthors described a 54-year-old White male patient who had been using kratom for the previous four to five years to reduce opioid use. During this period, he consumed kratom powder mixed with orange juice three to four times a day. He presented with “diffuse hyperpigmented patches on his arms and face in a photodistributed manner, with notable sparing of the knuckles on both hands.”
 

Dark Gray-Blue Skin

In the more recent case report, Ms. Patel and Dr. Phelan described a 30-year-old White male patient who presented with dark gray-blue skin coloring on his cheeks, back of his neck, and the backs of his hands and forearms. He had no other medical conditions and did not take any medications or supplements that cause hyperpigmentation while using kratom.

The patient had been taking kratom for years in the wake of an opioid addiction following medications for a high school injury. He developed an opioid use disorder and tried to replace his pain medications with kratom.

“The patient stopped using kratom in May 2022, but the discoloration remains. It has not regressed in the following 16 months after discontinuing kratom use,” the authors wrote, noting that “whether or not the hyperpigmentation is able to regress is unknown.”

Dr. Woolery-Lloyd is a consultant for AbbVie, Incyte, Johnson & Johnson Consumer, LivDerm, and L’Oreal; a speaker for Eli Lilly, Incyte, L’Oreal, and Ortho Dermatologics; and a researcher/investigator for AbbVie, Allergan, Eirion Therapeutics, Galderma, Pfizer, Sanofi, and Vyne Therapeutics.
 

According to an information page on kratom on the Food and Drug Administration website, health care professionals and consumers can report adverse reactions associated with kratom to the FDA’s MedWatch program.

A version of this article appeared on Medscape.com.

CHICAGO —The use of kratom, an opioid-like supplement widely available over the counter at convenience stores, smoke shops, and online, is resulting in emerging cases of hyperpigmentation, most often on the face and hands.

“This is something we will see more and more,” Heather Woolery-Lloyd, MD, director of the Skin of Color Division at the University of Miami Department of Dermatology, said at the Pigmentary Disorders Exchange Symposium. The key marker of this hyperpigmentation, she said, is that “it’s strongly photoaccentuated,” affecting areas exposed to the sun — but it also tends to spare the knuckles on patients’ hands.
 

Used Like an Opioid, But It’s Not Regulated

Kratom is a plant common in southeast Asia and is used as an analgesic. It’s marketed as a “legal opioid” or “legal high” and is sold in 2- or 3-ounce containers of extract or sold as a powder, Dr. Woolery-Lloyd said. The leaves may be boiled into a tea, smoked, chewed, or put into capsules, according to a case report published in February in the Journal of Integrative Dermatology. It is used worldwide and is not regulated in the United States.

“Many of our patients think kratom is a safe, herbal supplement” but often don’t know it can have several side effects and can be addictive, Dr. Woolery-Lloyd said. Its popularity is increasing as reflected by the number of posts related to kratom on social media platforms.

In the February case report, Shaina Patel, BA, and Nathaniel Phelan, MD, from Kansas City University, Kansas City, Missouri, wrote that side effects of kratom include drowsiness, tachycardia, vomiting, respiratory depression, and cardiac arrest, in addition to confusion and hallucinations.

Kratom also has many different effects on the psyche, Dr. Woolery-Lloyd said at the meeting. At low doses, it blocks the reuptake of norepinephrine, serotonin, and dopamine, producing a motivational effect, and at high doses, it creates an analgesic, calming effect. And people who chronically consume high doses of kratom may be susceptible to hyperpigmentation.

Kratom-associated hyperpigmentation should be considered as a diagnosis when evaluating patients for other drug-associated pigmentary disorders, “especially if pigment is photodistributed,” she said. “If you see new-onset hyperpigmentation or onset over several months and it’s very photoaccentuated, definitely ask about use of kratom.”
 

Case Reports Show Patterns of Presentation

A 2022 report from Landon R. Powell, BS, with the department of biology, Whitworth University in Spokane, Washington, and coauthors, published in JAAD Case Reports, noted that kratom use in the United States has increased dramatically. “As measured by call reports to the United States National Poison Data System, in 2011, there were 11 reported kratom exposures, and in the first 7 months of 2018, there were 357 reported exposures,” they wrote.

An estimated 1.7 million Americans aged ≥ 12 years said they had used kratom in the previous year, according to the Substance Abuse and Mental Health Services Administration 2021 National Survey on Drug Use and Health.

In the case report, Mr. Powell and coauthors described a 54-year-old White male patient who had been using kratom for the previous four to five years to reduce opioid use. During this period, he consumed kratom powder mixed with orange juice three to four times a day. He presented with “diffuse hyperpigmented patches on his arms and face in a photodistributed manner, with notable sparing of the knuckles on both hands.”
 

Dark Gray-Blue Skin

In the more recent case report, Ms. Patel and Dr. Phelan described a 30-year-old White male patient who presented with dark gray-blue skin coloring on his cheeks, back of his neck, and the backs of his hands and forearms. He had no other medical conditions and did not take any medications or supplements that cause hyperpigmentation while using kratom.

The patient had been taking kratom for years in the wake of an opioid addiction following medications for a high school injury. He developed an opioid use disorder and tried to replace his pain medications with kratom.

“The patient stopped using kratom in May 2022, but the discoloration remains. It has not regressed in the following 16 months after discontinuing kratom use,” the authors wrote, noting that “whether or not the hyperpigmentation is able to regress is unknown.”

Dr. Woolery-Lloyd is a consultant for AbbVie, Incyte, Johnson & Johnson Consumer, LivDerm, and L’Oreal; a speaker for Eli Lilly, Incyte, L’Oreal, and Ortho Dermatologics; and a researcher/investigator for AbbVie, Allergan, Eirion Therapeutics, Galderma, Pfizer, Sanofi, and Vyne Therapeutics.
 

According to an information page on kratom on the Food and Drug Administration website, health care professionals and consumers can report adverse reactions associated with kratom to the FDA’s MedWatch program.

A version of this article appeared on Medscape.com.

The Diagnosis: Erythema Ab Igne

Based on the patient's long-standing history of back pain treated with heating pads as well as the normal laboratory findings and skin examination, a diagnosis of erythema ab igne (EAI) was made.

Erythema ab igne presents as reticulated brownish erythema or hyperpigmentation on sites exposed to prolonged use of heat sources such as heating pads, laptops, and space heaters. Erythema ab igne most commonly affects the lower back, thighs, or legs^1-6; however, EAI can appear on atypical sites such as the forehead and eyebrows due to newer technology (eg, virtual reality headsets).⁷ The level of heat required for EAI to occur is below the threshold for thermal burns (<45 °C [113 °F]).1 Erythema ab igne can occur at any age, and woman are more commonly affected than men.⁸ The pathophysiology currently is unknown; however, recurrent and prolonged heat exposure may damage superficial vessels. As a result, hemosiderin accumulates in the skin, and hyperpigmentation subsequently occurs.⁹

The diagnosis of EAI is clinical, and early stages of the rash present as blanching reticulated erythema in areas associated with heat exposure. If the offending source of heat is not removed, EAI can progress to nonblanching, fixed, hyperpigmented plaques with skin atrophy, bullae, or hyperkeratosis. Patients often are asymptomatic; however, mild burning may occur.² Histopathology reveals cellular atypia, epidermal atrophy, dilation of dermal blood vessels, a minute inflammatory infiltrate, and keratinocyte apoptosis.¹⁰ Skin biopsy may be necessary in cases of suspected malignancy due to chronic heat exposure. Lesions that ulcerate or evolve should raise suspicion for malignancy.¹¹ Squamous cell carcinoma is the most common malignancy associated with EAI; other malignancies that may manifest include basal cell carcinoma, Merkel cell carcinoma, or cutaneous marginal zone lymphoma.^2,12-14

Erythema ab igne often is mistaken for livedo reticularis, which appears more erythematous without hyperpigmentation or epidermal changes and may be associated with a pathologic state.¹⁵ The differential diagnosis in our patient, who was in her 40s with a history of fatigue and joint pain, included livedo reticularis associated with lupus; however, the history of heating pad use, normal laboratory findings, and presence of epidermal changes suggested EAI. Lupus typically affects the hand and knee joints.¹⁶ Additionally, livedo reticularis more commonly appears on the legs.¹⁵

Other differentials for EAI include livedo racemosa, cutaneous T-cell lymphoma, and cutis marmorata. Livedo racemosa presents with broken rings of erythema in young to middle-aged women and primarily affects the trunk and proximal limbs. It is associated with an underlying condition such as polyarteritis nodosa and less commonly with lupus erythematosus with antiphospholipid or Sneddon syndrome.^15,17 Cutaneous T-cell lymphoma typically manifests with poikilodermatous patches larger than the palm, especially in covered areas of skin.¹⁸ Cutis marmorata is transient and temperature dependent.⁹

The key intervention for EAI is removal of the offending heat source.² Patients should be counseled that the erythema and hyperpigmentation may take months to years to resolve. Topical hydroquinone or tretinoin may be used in cases of persistent hyperpigmentation.¹⁹ Patients who continue to use heating pads for long-standing pain should be advised to limit their use to short intervals without occlusion. If malignancy is a concern, a biopsy should be performed.²⁰

The Diagnosis: Erythema Ab Igne

Based on the patient's long-standing history of back pain treated with heating pads as well as the normal laboratory findings and skin examination, a diagnosis of erythema ab igne (EAI) was made.

Erythema ab igne presents as reticulated brownish erythema or hyperpigmentation on sites exposed to prolonged use of heat sources such as heating pads, laptops, and space heaters. Erythema ab igne most commonly affects the lower back, thighs, or legs^1-6; however, EAI can appear on atypical sites such as the forehead and eyebrows due to newer technology (eg, virtual reality headsets).⁷ The level of heat required for EAI to occur is below the threshold for thermal burns (<45 °C [113 °F]).1 Erythema ab igne can occur at any age, and woman are more commonly affected than men.⁸ The pathophysiology currently is unknown; however, recurrent and prolonged heat exposure may damage superficial vessels. As a result, hemosiderin accumulates in the skin, and hyperpigmentation subsequently occurs.⁹

The diagnosis of EAI is clinical, and early stages of the rash present as blanching reticulated erythema in areas associated with heat exposure. If the offending source of heat is not removed, EAI can progress to nonblanching, fixed, hyperpigmented plaques with skin atrophy, bullae, or hyperkeratosis. Patients often are asymptomatic; however, mild burning may occur.² Histopathology reveals cellular atypia, epidermal atrophy, dilation of dermal blood vessels, a minute inflammatory infiltrate, and keratinocyte apoptosis.¹⁰ Skin biopsy may be necessary in cases of suspected malignancy due to chronic heat exposure. Lesions that ulcerate or evolve should raise suspicion for malignancy.¹¹ Squamous cell carcinoma is the most common malignancy associated with EAI; other malignancies that may manifest include basal cell carcinoma, Merkel cell carcinoma, or cutaneous marginal zone lymphoma.^2,12-14

Erythema ab igne often is mistaken for livedo reticularis, which appears more erythematous without hyperpigmentation or epidermal changes and may be associated with a pathologic state.¹⁵ The differential diagnosis in our patient, who was in her 40s with a history of fatigue and joint pain, included livedo reticularis associated with lupus; however, the history of heating pad use, normal laboratory findings, and presence of epidermal changes suggested EAI. Lupus typically affects the hand and knee joints.¹⁶ Additionally, livedo reticularis more commonly appears on the legs.¹⁵

Other differentials for EAI include livedo racemosa, cutaneous T-cell lymphoma, and cutis marmorata. Livedo racemosa presents with broken rings of erythema in young to middle-aged women and primarily affects the trunk and proximal limbs. It is associated with an underlying condition such as polyarteritis nodosa and less commonly with lupus erythematosus with antiphospholipid or Sneddon syndrome.^15,17 Cutaneous T-cell lymphoma typically manifests with poikilodermatous patches larger than the palm, especially in covered areas of skin.¹⁸ Cutis marmorata is transient and temperature dependent.⁹

The key intervention for EAI is removal of the offending heat source.² Patients should be counseled that the erythema and hyperpigmentation may take months to years to resolve. Topical hydroquinone or tretinoin may be used in cases of persistent hyperpigmentation.¹⁹ Patients who continue to use heating pads for long-standing pain should be advised to limit their use to short intervals without occlusion. If malignancy is a concern, a biopsy should be performed.²⁰

The Diagnosis: Erythema Ab Igne

Based on the patient's long-standing history of back pain treated with heating pads as well as the normal laboratory findings and skin examination, a diagnosis of erythema ab igne (EAI) was made.

Erythema ab igne presents as reticulated brownish erythema or hyperpigmentation on sites exposed to prolonged use of heat sources such as heating pads, laptops, and space heaters. Erythema ab igne most commonly affects the lower back, thighs, or legs^1-6; however, EAI can appear on atypical sites such as the forehead and eyebrows due to newer technology (eg, virtual reality headsets).⁷ The level of heat required for EAI to occur is below the threshold for thermal burns (<45 °C [113 °F]).1 Erythema ab igne can occur at any age, and woman are more commonly affected than men.⁸ The pathophysiology currently is unknown; however, recurrent and prolonged heat exposure may damage superficial vessels. As a result, hemosiderin accumulates in the skin, and hyperpigmentation subsequently occurs.⁹

The diagnosis of EAI is clinical, and early stages of the rash present as blanching reticulated erythema in areas associated with heat exposure. If the offending source of heat is not removed, EAI can progress to nonblanching, fixed, hyperpigmented plaques with skin atrophy, bullae, or hyperkeratosis. Patients often are asymptomatic; however, mild burning may occur.² Histopathology reveals cellular atypia, epidermal atrophy, dilation of dermal blood vessels, a minute inflammatory infiltrate, and keratinocyte apoptosis.¹⁰ Skin biopsy may be necessary in cases of suspected malignancy due to chronic heat exposure. Lesions that ulcerate or evolve should raise suspicion for malignancy.¹¹ Squamous cell carcinoma is the most common malignancy associated with EAI; other malignancies that may manifest include basal cell carcinoma, Merkel cell carcinoma, or cutaneous marginal zone lymphoma.^2,12-14

Erythema ab igne often is mistaken for livedo reticularis, which appears more erythematous without hyperpigmentation or epidermal changes and may be associated with a pathologic state.¹⁵ The differential diagnosis in our patient, who was in her 40s with a history of fatigue and joint pain, included livedo reticularis associated with lupus; however, the history of heating pad use, normal laboratory findings, and presence of epidermal changes suggested EAI. Lupus typically affects the hand and knee joints.¹⁶ Additionally, livedo reticularis more commonly appears on the legs.¹⁵

Other differentials for EAI include livedo racemosa, cutaneous T-cell lymphoma, and cutis marmorata. Livedo racemosa presents with broken rings of erythema in young to middle-aged women and primarily affects the trunk and proximal limbs. It is associated with an underlying condition such as polyarteritis nodosa and less commonly with lupus erythematosus with antiphospholipid or Sneddon syndrome.^15,17 Cutaneous T-cell lymphoma typically manifests with poikilodermatous patches larger than the palm, especially in covered areas of skin.¹⁸ Cutis marmorata is transient and temperature dependent.⁹

The key intervention for EAI is removal of the offending heat source.² Patients should be counseled that the erythema and hyperpigmentation may take months to years to resolve. Topical hydroquinone or tretinoin may be used in cases of persistent hyperpigmentation.¹⁹ Patients who continue to use heating pads for long-standing pain should be advised to limit their use to short intervals without occlusion. If malignancy is a concern, a biopsy should be performed.²⁰

The Comparison

A Plantar hyperpigmentation (benign ethnic melanosis) on the sole of the foot in a 62-year-old man of African descent with deeply pigmented skin. Dermoscopy showed a parallel ridge pattern even though the hyperpigmentation was benign (inset).

B Melanoma in situ with multicomponent hyperpigmentation on the sole of the foot in a 65-year-old Hispanic woman. Dermoscopy revealed a parallel ridge pattern (inset).

Plantar hyperpigmentation (also known as plantar melanosis [increased melanin], volar pigmented macules, benign racial melanosis, acral pigmentation, acral ethnic melanosis, or mottled hyperpigmentation of the plantar surface) is a benign finding in many individuals and is especially prevalent in those with darker skin tones. Acral refers to manifestation on the hands and feet, volar on the palms and soles, and plantar on the soles only. Here, we focus on plantar hyperpigmentation. We use the terms ethnic and racial interchangeably.

It is critically important to differentiate benign hyperpigmentation, which is common in patients with skin of color, from melanoma. Although rare, Black patients in the United States experience high morbidity and mortality from acral melanoma, which often is diagnosed late in the disease course.¹

There are many causes of hyperpigmentation on the plantar surfaces, including benign ethnic melanosis, nevi, melanoma, infections such as syphilis and tinea nigra, conditions such as Peutz-Jeghers syndrome and Laugier-Hunziker syndrome, and postinflammatory hyperpigmentation secondary to atopic dermatitis and psoriasis. We focus on the most common causes, ethnic melanosis and nevi, as well as melanoma, which is the deadliest cause.

Epidemiology

In a 1980 study (N=251), Black Americans had a high incidence of plantar hyperpigmentation, with 52% of affected patients having dark brown skin and 31% having light brown skin.²

The epidemiology of melanoma varies by race/ethnicity. Melanoma in Black individuals is relatively rare, with an annual incidence of approximately 1 in 100,000 individuals.³ However, when individuals with skin of color develop melanoma, they are more likely than their White counterparts to have acral melanoma (acral lentiginous melanoma), one of the deadliest types.¹ In a case series of Black patients with melanoma (N=48) from 2 tertiary care centers in Texas, 30 of 40 primary cutaneous melanomas (75%) were located on acral skin.⁴ Overall, 13 patients developed stage IV disease and 12 died due to disease progression. All patients who developed distant metastases or died of melanoma had acral melanoma.⁴ Individuals of Asian descent also have a high incidence of acral melanoma, as shown in research from Japan.^5-9

Key clinical features in individuals with darker skin tones

Dermoscopy is an evidence-based clinical examination method for earlier diagnosis of cutaneous melanoma, including on acral skin.^10,11 Benign nevi on the volar skin as well as the palms and soles tend to have one of these 3 dermoscopic patterns: parallel furrow, lattice, or irregular fibrillar. The pattern that is most predictive of volar melanoma is the parallel ridge pattern (PRP) (Figures A and B [insets]), which showed a high specificity (99.0%) and very high negative predictive value (97.7%) for malignant melanoma in a Japanese population.⁷ The PRP data from this study cannot be applied reliably to Black individuals, especially because benign ethnic melanosis and other benign conditions can demonstrate PRP.¹² Reliance on the PRP as a diagnostic clue could result in unneccessary biopsies in as many as 50% of Black patients with benign plantar hyperpigmentation.² Furthermore, biopsies of the plantar surface can be painful and cause pain while walking.

It has been suggested that PRP seen on dermoscopy in benign hyperpigmentation such as ethnic melanosis and nevi may preserve the acrosyringia (eccrine gland openings on the ridge), whereas PRP in melanoma may obliterate the acrosyringia.¹³ This observation is based on case reports only and needs further study. However, if validated, it could be a useful diagnostic clue.

Worth noting

In a retrospective cohort study of skin cancer in Black individuals (n=165) at a New York City–based cancer center from 2000 to 2020, 68% of patients were diagnosed with melanomas—80% were the acral subtype and 75% displayed a PRP. However, the surrounding uninvolved background skin, which was visible in most cases, also demonstrated a PRP.¹⁴ Because of the high morbidity and mortality rates of acral melanoma, clinicians should biopsy or immediately refer patients with concerning plantar hyperpigmentation to a dermatologist.

Health disparity highlight

The mortality rate for acral melanoma in Black patients is disproportionately high for the following reasons^15,16:

• Patients and health care providers do not expect to see melanoma in Black patients (it truly is rare!), so screening and education on sun protection are limited.
• Benign ethnic melanosis makes it more difficult to distinguish between early acral melanoma and benign skin changes.
• Black patients and other US patient populations with skin of color may be less likely to have health insurance, which contributes to inequities in access to health care. As of 2022, the uninsured rates for nonelderly American Indian and Alaska Native, Hispanic, Native Hawaiian and Other Pacific Islander, Black, and White individuals were 19.1%, 18.0%, 12.7%, 10.0%, and 6.6%, respectively.¹⁷

Multi-institutional registries could improve understanding of acral melanoma in Black patients.⁴ More studies are needed to help differentiate between the dermoscopic finding of PRP in benign ethnic melanosis vs malignant melanoma.

The Comparison

A Plantar hyperpigmentation (benign ethnic melanosis) on the sole of the foot in a 62-year-old man of African descent with deeply pigmented skin. Dermoscopy showed a parallel ridge pattern even though the hyperpigmentation was benign (inset).

B Melanoma in situ with multicomponent hyperpigmentation on the sole of the foot in a 65-year-old Hispanic woman. Dermoscopy revealed a parallel ridge pattern (inset).

Plantar hyperpigmentation (also known as plantar melanosis [increased melanin], volar pigmented macules, benign racial melanosis, acral pigmentation, acral ethnic melanosis, or mottled hyperpigmentation of the plantar surface) is a benign finding in many individuals and is especially prevalent in those with darker skin tones. Acral refers to manifestation on the hands and feet, volar on the palms and soles, and plantar on the soles only. Here, we focus on plantar hyperpigmentation. We use the terms ethnic and racial interchangeably.

It is critically important to differentiate benign hyperpigmentation, which is common in patients with skin of color, from melanoma. Although rare, Black patients in the United States experience high morbidity and mortality from acral melanoma, which often is diagnosed late in the disease course.¹

There are many causes of hyperpigmentation on the plantar surfaces, including benign ethnic melanosis, nevi, melanoma, infections such as syphilis and tinea nigra, conditions such as Peutz-Jeghers syndrome and Laugier-Hunziker syndrome, and postinflammatory hyperpigmentation secondary to atopic dermatitis and psoriasis. We focus on the most common causes, ethnic melanosis and nevi, as well as melanoma, which is the deadliest cause.

Epidemiology

In a 1980 study (N=251), Black Americans had a high incidence of plantar hyperpigmentation, with 52% of affected patients having dark brown skin and 31% having light brown skin.²

The epidemiology of melanoma varies by race/ethnicity. Melanoma in Black individuals is relatively rare, with an annual incidence of approximately 1 in 100,000 individuals.³ However, when individuals with skin of color develop melanoma, they are more likely than their White counterparts to have acral melanoma (acral lentiginous melanoma), one of the deadliest types.¹ In a case series of Black patients with melanoma (N=48) from 2 tertiary care centers in Texas, 30 of 40 primary cutaneous melanomas (75%) were located on acral skin.⁴ Overall, 13 patients developed stage IV disease and 12 died due to disease progression. All patients who developed distant metastases or died of melanoma had acral melanoma.⁴ Individuals of Asian descent also have a high incidence of acral melanoma, as shown in research from Japan.^5-9

Key clinical features in individuals with darker skin tones

Dermoscopy is an evidence-based clinical examination method for earlier diagnosis of cutaneous melanoma, including on acral skin.^10,11 Benign nevi on the volar skin as well as the palms and soles tend to have one of these 3 dermoscopic patterns: parallel furrow, lattice, or irregular fibrillar. The pattern that is most predictive of volar melanoma is the parallel ridge pattern (PRP) (Figures A and B [insets]), which showed a high specificity (99.0%) and very high negative predictive value (97.7%) for malignant melanoma in a Japanese population.⁷ The PRP data from this study cannot be applied reliably to Black individuals, especially because benign ethnic melanosis and other benign conditions can demonstrate PRP.¹² Reliance on the PRP as a diagnostic clue could result in unneccessary biopsies in as many as 50% of Black patients with benign plantar hyperpigmentation.² Furthermore, biopsies of the plantar surface can be painful and cause pain while walking.

It has been suggested that PRP seen on dermoscopy in benign hyperpigmentation such as ethnic melanosis and nevi may preserve the acrosyringia (eccrine gland openings on the ridge), whereas PRP in melanoma may obliterate the acrosyringia.¹³ This observation is based on case reports only and needs further study. However, if validated, it could be a useful diagnostic clue.

Worth noting

In a retrospective cohort study of skin cancer in Black individuals (n=165) at a New York City–based cancer center from 2000 to 2020, 68% of patients were diagnosed with melanomas—80% were the acral subtype and 75% displayed a PRP. However, the surrounding uninvolved background skin, which was visible in most cases, also demonstrated a PRP.¹⁴ Because of the high morbidity and mortality rates of acral melanoma, clinicians should biopsy or immediately refer patients with concerning plantar hyperpigmentation to a dermatologist.

Health disparity highlight

The mortality rate for acral melanoma in Black patients is disproportionately high for the following reasons^15,16:

• Patients and health care providers do not expect to see melanoma in Black patients (it truly is rare!), so screening and education on sun protection are limited.
• Benign ethnic melanosis makes it more difficult to distinguish between early acral melanoma and benign skin changes.
• Black patients and other US patient populations with skin of color may be less likely to have health insurance, which contributes to inequities in access to health care. As of 2022, the uninsured rates for nonelderly American Indian and Alaska Native, Hispanic, Native Hawaiian and Other Pacific Islander, Black, and White individuals were 19.1%, 18.0%, 12.7%, 10.0%, and 6.6%, respectively.¹⁷

Multi-institutional registries could improve understanding of acral melanoma in Black patients.⁴ More studies are needed to help differentiate between the dermoscopic finding of PRP in benign ethnic melanosis vs malignant melanoma.

The Comparison

A Plantar hyperpigmentation (benign ethnic melanosis) on the sole of the foot in a 62-year-old man of African descent with deeply pigmented skin. Dermoscopy showed a parallel ridge pattern even though the hyperpigmentation was benign (inset).

B Melanoma in situ with multicomponent hyperpigmentation on the sole of the foot in a 65-year-old Hispanic woman. Dermoscopy revealed a parallel ridge pattern (inset).

Plantar hyperpigmentation (also known as plantar melanosis [increased melanin], volar pigmented macules, benign racial melanosis, acral pigmentation, acral ethnic melanosis, or mottled hyperpigmentation of the plantar surface) is a benign finding in many individuals and is especially prevalent in those with darker skin tones. Acral refers to manifestation on the hands and feet, volar on the palms and soles, and plantar on the soles only. Here, we focus on plantar hyperpigmentation. We use the terms ethnic and racial interchangeably.

It is critically important to differentiate benign hyperpigmentation, which is common in patients with skin of color, from melanoma. Although rare, Black patients in the United States experience high morbidity and mortality from acral melanoma, which often is diagnosed late in the disease course.¹

There are many causes of hyperpigmentation on the plantar surfaces, including benign ethnic melanosis, nevi, melanoma, infections such as syphilis and tinea nigra, conditions such as Peutz-Jeghers syndrome and Laugier-Hunziker syndrome, and postinflammatory hyperpigmentation secondary to atopic dermatitis and psoriasis. We focus on the most common causes, ethnic melanosis and nevi, as well as melanoma, which is the deadliest cause.

Epidemiology

In a 1980 study (N=251), Black Americans had a high incidence of plantar hyperpigmentation, with 52% of affected patients having dark brown skin and 31% having light brown skin.²

The epidemiology of melanoma varies by race/ethnicity. Melanoma in Black individuals is relatively rare, with an annual incidence of approximately 1 in 100,000 individuals.³ However, when individuals with skin of color develop melanoma, they are more likely than their White counterparts to have acral melanoma (acral lentiginous melanoma), one of the deadliest types.¹ In a case series of Black patients with melanoma (N=48) from 2 tertiary care centers in Texas, 30 of 40 primary cutaneous melanomas (75%) were located on acral skin.⁴ Overall, 13 patients developed stage IV disease and 12 died due to disease progression. All patients who developed distant metastases or died of melanoma had acral melanoma.⁴ Individuals of Asian descent also have a high incidence of acral melanoma, as shown in research from Japan.^5-9

Key clinical features in individuals with darker skin tones

Dermoscopy is an evidence-based clinical examination method for earlier diagnosis of cutaneous melanoma, including on acral skin.^10,11 Benign nevi on the volar skin as well as the palms and soles tend to have one of these 3 dermoscopic patterns: parallel furrow, lattice, or irregular fibrillar. The pattern that is most predictive of volar melanoma is the parallel ridge pattern (PRP) (Figures A and B [insets]), which showed a high specificity (99.0%) and very high negative predictive value (97.7%) for malignant melanoma in a Japanese population.⁷ The PRP data from this study cannot be applied reliably to Black individuals, especially because benign ethnic melanosis and other benign conditions can demonstrate PRP.¹² Reliance on the PRP as a diagnostic clue could result in unneccessary biopsies in as many as 50% of Black patients with benign plantar hyperpigmentation.² Furthermore, biopsies of the plantar surface can be painful and cause pain while walking.

It has been suggested that PRP seen on dermoscopy in benign hyperpigmentation such as ethnic melanosis and nevi may preserve the acrosyringia (eccrine gland openings on the ridge), whereas PRP in melanoma may obliterate the acrosyringia.¹³ This observation is based on case reports only and needs further study. However, if validated, it could be a useful diagnostic clue.

Worth noting

In a retrospective cohort study of skin cancer in Black individuals (n=165) at a New York City–based cancer center from 2000 to 2020, 68% of patients were diagnosed with melanomas—80% were the acral subtype and 75% displayed a PRP. However, the surrounding uninvolved background skin, which was visible in most cases, also demonstrated a PRP.¹⁴ Because of the high morbidity and mortality rates of acral melanoma, clinicians should biopsy or immediately refer patients with concerning plantar hyperpigmentation to a dermatologist.

Health disparity highlight

The mortality rate for acral melanoma in Black patients is disproportionately high for the following reasons^15,16:

• Patients and health care providers do not expect to see melanoma in Black patients (it truly is rare!), so screening and education on sun protection are limited.
• Benign ethnic melanosis makes it more difficult to distinguish between early acral melanoma and benign skin changes.
• Black patients and other US patient populations with skin of color may be less likely to have health insurance, which contributes to inequities in access to health care. As of 2022, the uninsured rates for nonelderly American Indian and Alaska Native, Hispanic, Native Hawaiian and Other Pacific Islander, Black, and White individuals were 19.1%, 18.0%, 12.7%, 10.0%, and 6.6%, respectively.¹⁷

Multi-institutional registries could improve understanding of acral melanoma in Black patients.⁴ More studies are needed to help differentiate between the dermoscopic finding of PRP in benign ethnic melanosis vs malignant melanoma.

Melasma is an acquired hyperpigmentation disorder characterized by irregular brown macules and patches that usually appear on sun-exposed areas of the skin. The term melasma originates from the Greek word melas meaning black.¹ Facial melasma is divided into 2 groups according to its clinical distribution: centrofacial lesions are located in the center of the face (eg, the glabellar, frontal, nasal, zygomatic, upper lip, chin areas), and peripheral lesions manifest on the frontotemporal, preauricular, and mandibular regions.^1,2 There is debate on the categorization of zygomatic (or malar) melasma; some researchers argue it should be categorized independent of other areas, while others include malar melasma in the centrofacial group because of its frequent association with the centrofacial type, especially with glabellar lesions.² Mandibular melasma is rare and occurs mostly in postmenopausal women after intense sun exposure.^1,2 Although the etiopathogenesis of the disease is not clearly known, increased melanogenesis, extracellular matrix alterations, inflammation, and angiogenesis are assumed to play a role.³ Various risk factors such as genetic predisposition, UV radiation (UVR) exposure, pregnancy, thyroid dysfunction, and exogenous hormones (eg, oral contraceptives, hormone replacement therapy) have been identified; phototoxic drugs, anticonvulsants, and some cosmetics also have been implicated.^4,5 Exposure to UVR is thought to be the main triggering environmental factor by inducing both melanin production and oxidative stress.⁵ However, it also has been shown that visible light can induce hyperpigmentation in darker skin types.⁶

The presence of oxidative stress in melasma recently has become an intriguing topic of interest. First, the presence of oxidative stress in the etiopathogenesis of melasma was thought to be based on the effectiveness of antioxidants in treatment. A few studies also have confirmed the presence of oxidative stress in melasma.^7-10 Classically, oxidative stress can be described as a disturbance in the balance between oxidants and antioxidants. Reactive oxygen species (ROS) are highly reactive molecules due to the unpaired electrons in their structure. Although ROS are present at low levels in physiologic conditions and are involved in critical physiologic events, they damage cellular components such as fat, protein, and nucleic acid at high concentrations.⁵

Dynamic thiol/disulfide homeostasis is one of the most important markers of oxidative stress in biological systems. Thiols are organic compounds containing a sulfhydryl (-SH) group. Thiols are considered highly potent antioxidants because they reduce unstable free radicals by donating electrons. They are the first antioxidants to be depleted in an oxidative environment.^11,12 In case of oxidative stress, they transform into reversible forms called disulfide bridges between 2 thiol groups. Disulfide bridges can be reduced back to thiol groups, which is how dynamic thiol/disulfide homeostasis is maintained. Dynamic thiol/disulfide homeostasis is responsible for cellular events such as antioxidant defense, signal transduction, regulation of enzyme function, and apoptosis.^11,12

The aim of this study was to evaluate the presence of oxidative stress in melasma by comparing dynamic thiol/disulfide homeostasis in patients with melasma compared with age- and sex-matched healthy controls.

Materials and Methods

Participants and Eligibility Criteria—We conducted a prospective study in a tertiary-care hospital (Ankara Bilkent City Hospital [Ankara, Turkey]) of patients with melasma who were followed from October 2021 to October 2022 compared with age- and sex-matched healthy volunteers. Ethics committee approval was obtained from Ankara Bilkent City Hospital before the study (E2-21-881)(13.10.2021). Written informed consent was obtained from all participants, and all were older than 18 years. Patients were excluded if there was the presence of any systemic disease or dermatologic disease other than melasma; smoking or alcohol use; any use of vitamins, food supplements, or any medication in the last 3 months; or pregnancy.

Melasma Severity—The modified melasma area and severity index (mMASI) score was used to determine the severity of melasma. The score is calculated from assessments of the darkness of the pigmentation and the percentage of affected area on the face. The mMASI score is the sum of the darkness score (D); area score (A); and separate fixed coefficients for the forehead, as well as the right malar, left malar, and chin regions.¹³ The mMASI score, with a range of 0 to 24, is a reliable and objective marker in the calculation of melasma severity.⁴

Biochemical Analysis of Samples—The 6-cc peripheral fasting venous blood samples obtained from the study participants were centrifuged at 1500 g for 10 minutes, and the separated sera were stored in a freezer at −80 °C until the time of analysis. When the study was completed, the disulfide and thiol values were analyzed. Serum native and total thiol concentrations indicating thiol/disulfide homeostasis were calculated by a new fully automatic colorimetric method developed by Erel and Neselioglu.¹⁴ Using this method, short disulfide bonds are first reduced with sodium borohydride solution to form free-functional thiol groups, and then the unused sodium borohydride is removed using formaldehyde. Finally, all thiol groups are reacted with 5,5’-dithiobis-(2-nitrobenzoic) acid (Ellman reagent), and all thiol groups are detected after reaction with 5,5’-dithiobis-(2-nitrobenzoic) acid. When a disulfide bond (−S−S−) is reduced, 2 thiol groups are formed. For this reason, half of the difference between total thiol (-SH + the amount of thiol formed by the reduction of disulfides) and native thiol (-SH) corresponds to the dynamic disulfide amount (total thiol − native thiol/2).¹⁴

Statistical Analysis—Statistical analysis was performed using SPSS software (version 24.0). Descriptive statistics were presented as numbers and percentages for categorical variables, and numerical variables were presented as mean, SD, median, minimum, maximum, 25th quartile, and 75th quartile. The conformity of the variables to normal distribution was examined using visual (histograms and probability plots) and analytical methods (Kolmogorov-Smirnov/Shapiro-Wilk tests). In pairwise group comparisons for numerical variables, a Mann-Whitney U test was used when normal distribution was not met, and a t test was used when normal distribution was met. The statistical significance level was accepted as P<.05.

Results

Our study included 67 patients with melasma and 41 healthy age- and sex-matched controls. Of the participants with melasma, 60 (89.5%) were female and 7 (10.5%) were male. The control group was similar to the melasma group in terms of sex (87.8% female vs 12.2% male [P=.59]). The mean age (SD) was 33.1 (6.7) years in the melasma group and 31.9 (6.7) years in the control group. Age was similar across both groups (P=.41). All participants were of Asian race, and Fitzpatrick skin types (types II–IV) were similar across both groups.

Fifty-four (80.6%) participants had centrofacial melasma and 13 (19.4%) had mixed-type melasma. The mMASI score ranged from 3 to 20; the mean (SD) mMASI score was 11.28 (3.2). Disease duration ranged from 2 to 72 months; the mean (SD) disease duration was 12.26 (6.3) months. The demographics and clinical characteristics of the study group are shown in eTable 1.

eTable 2 provides a summary of disulfide, native thiol, and total thiol levels, as well as disulfide/native thiol, disulfide/total thiol, and native thiol/total thiol ratios in the study population. Disulfide/native thiol and disulfide/total thiol ratios were higher in melasma patients (Figure 1), whereas the native thiol/total thiol ratio was higher in the control group (P=.025, P=.025, and P=.026, respectively).

All correlations between age, disease duration, and mMASI scores and disulfide, native thiol, and total thiol levels, as well as disulfide/native thiol, disulfide/total thiol, and native thiol/total thiol ratios, are summarized in eTable 3. No significant correlation was observed between age and disease duration and disulfide, native thiol, and total thiol levels or disulfide/native thiol, disulfide/total thiol, and native thiol/total thiol ratios.

We independently assessed whether Fitzpatrick skin types II, III, and IV exhibited distinct levels of oxidative stress in clinical melasma. There were no significant correlations with Fitzpatrick skin type (disulfide/native thiol, P=.25; disulfide/total thiol, P=.19). We further evaluated if the thiol/disulfide parameters were correlated with duration of melasma by dividing the melasma patients into 3 groups (<6 months [n=12], 6–18 months [n=32], >18 months [n=23]), but there was not any significant correlation (disulfide/native thiol, P=.15; disulfide/total thiol, P=.15). We also divided our patients into 3 groups according to age (<27 years [n=14], 27–36 years [n=33], >36 years [n=20]). There was no correlation of the parameters with age (disulfide/native thiol, P=.15; disulfide/total thiol, P=.14).

There was a positive correlation between mMASI score and disulfide, native thiol, and total thiol levels and disulfide/native thiol and disulfide/total thiol ratios, as well as a negative correlation between mMASI score and native thiol/total thiol ratio. The correlations between mMASI scores and disulfide/native thiol and disulfide/total thiol ratios are shown in Figure 2 and eTable 3.

Comment

Melasma is a common condition that may cause psychosocial problems in affected patients and negatively affect quality of life.¹ It occurs in all races but is more common in individuals with darker skin types (eg, Fitzpatrick skin types III and IV). Although melasma is more common in women during reproductive years (50%–70%), it also has been observed in 10% to 30% of men.⁵

Treatment options include topical bleaching agents, chemical peels, and laser therapy, as well as discontinuation of medications that may potentially trigger melasma; use of broad-spectrum sunscreens also is recommended.⁴ Vitamins A, C, and E, as well as niacinamide, are used in the treatment of melasma, especially for their antioxidant properties. The key role of antioxidants in the treatment of melasma supports the importance of oxidative stress in the pathogenesis.⁷ Melasma often is challenging to treat, particularly the mixed or dermal types, due to their stubborn nature. This condition poses a considerable therapeutic challenge for dermatologists.⁴

Oxidative stress and oxidant-antioxidant imbalance previously have been studied in various diseases, but research investigating the presence of oxidative stress in melasma are limited.^7-10 Exposure of the skin to polluted air and intense UVR, as well as some food by-products, cosmetics, and drugs (eg, oral contraceptives), can directly or indirectly cause ROS production in the skin. Reactive oxygen species are thought to be involved in the pathophysiology of melasma by affecting apoptotic pathways and causing cell proliferation. The intermediate heme pathway has pro-oxidant effects and produces ROS and metabolites such as redox-active quinines. Exposure to UVR leads to the generation of ROS, highlighting the role of oxidative stress in the onset of melasma. ⁵

In any cutaneous disease in which oxidative stress plays a role, oxidant and antioxidant levels may be expected to vary both locally and systemically; however, measurement of oxidative stress markers in serum instead of skin is technically and economically more advantageous.⁸ Firstly, serum collection is less invasive and technically simpler than skin biopsies. Drawing blood is a routine procedure that requires minimal specialized equipment and training compared to the extraction and processing of skin samples. Secondly, analyzing serum samples generally is less expensive than processing skin tissue.⁸

In our study, we evaluated dynamic thiol/disulfide homeostasis in serum to investigate the presence of oxidative stress in the setting of melasma. Functional sulfhydryl (-SH) groups in thiols act as substrates for antioxidant enzymes and as free-radical scavengers. They constitute one of the most powerful defense systems against the unwanted effects of ROS. Thiols, which become the main target of ROS under oxidative stress, oxidize with oxidant molecules and form disulfide bridges.¹⁵

Thiol/disulfide homeostasis has been studied many times in dermatologic diseases,^16-19 and the results obtained from these studies are heterogenous depending on the extent of oxidative damage. It has been shown that thiol/disulfide homeostasis plays a role in oxidative stress in conditions such as psoriasis,¹⁷ seborrheic dermatitis,¹¹ atopic dermatitits,¹⁸ and rosacea.¹⁹ In our study, disulfide/native thiol and disulfide/total thiol levels were significantly higher (both P=.025) in the melasma group compared with the control group, which indicates that the thiol/disulfide balance in patients with melasma is shifted to disulfide formation and thiols are oxidized to disulfide bonds in the presence of oxidative stress.

Seçkin et al⁷ evaluated the role of oxidative stress in the pathogenesis of melasma and found that the serum levels of the antioxidants superoxide dismutase and glutathione peroxidase were significantly higher in the patient group compared with the control group (both P<.001). They also found that the levels of nitric oxide (another antioxidant) were increased in the patient group and the levels of protein carbonyl (an oxidative metabolite) were significantly lower (both P<.001). These findings indicated that free-radical damage may be involved in the pathogenesis of melasma.⁷

In a study of 75 patients with melasma, serum levels of the antioxidants melatonin and catalase were significantly (P<.001 and P=.001, respectively) lower in the melasma group compared with the control group, while serum levels of the oxidants protein carbonyl and nitric oxide were significantly higher (P=.002 and P=.001, respectively). No significant correlation was found between oxidative stress parameters and melasma severity.⁸

Choubey et al⁹ found that serum malondialdehyde (an end product of lipid peroxidation), superoxide dismutase, and glutathione peroxidase levels were significantly higher in the melasma group (n=50) compared with the control group (n=50)(all P<.001). In addition, a significant positive correlation (correlation coefficient, +0.307; P<.05) was found between serum malondialdehyde levels and melasma severity. The mean age (SD) of the patients was 32.22 (6.377) years, and the female (n=41) to male (n=9) ratio was 4.55:1. The most common melasma pattern was centrofacial, followed by malar.⁹

In a study with 50 melasma patients and 50 controls, Rahimi et al¹⁰ examined bilirubin and uric acid levels, which are major extracellular antioxidants. The mean age (SD) at disease onset was 32.6 (6.7) years, and the mean MASI score (SD) was 18.1 (9). Serum bilirubin levels were found to be higher in the melasma group than in the control group and were correlated with disease severity. No significant difference in uric acid levels was found between the groups, and no correlation was found between MASI score and bilirubin and uric acid levels.¹⁰

In our study, the melasma group was similar to those in other reportsin the literature regarding gender distribution, mean age, and melasma pattern.^7-10 Additionally, the correlation of mMASI score with disulfide/native thiol and disulfide/total thiol values in the melasma group suggested that oxidative stress also is correlated with melasma severity.

Thiol-based treatments such as n-acetyl cysteine, which contains a thiol compound, may be helpful in melasma.²⁰ In a double-blind, placebo-controlled study, topical n-acetyl cysteine combined with hydroquinone 2% was used in 10 female patients with melasma. Mild to strong bleaching of the skin was observed in 90% (9/10) of the patients.²¹ Systemic use of n-acetyl cysteine in melasma also may be a potential research topic.

Major limitations of our study were the small sample size and lack of measurement of oxidative stress parameters in the skin concurrently with serum.

Conclusion

In our study, the presence of oxidative stress in melasma was demonstrated by evaluating thiol/disulfide homeostasis—one of the strongest markers of oxidative stress. Oxidative stress also correlated with melasma disease severity in our analysis. The data obtained in this study may contribute to understanding the etiopathogenesis of melasma and may open new horizons in treatment; however, more comprehensive studies should be conducted to support our findings.

Melasma is an acquired hyperpigmentation disorder characterized by irregular brown macules and patches that usually appear on sun-exposed areas of the skin. The term melasma originates from the Greek word melas meaning black.¹ Facial melasma is divided into 2 groups according to its clinical distribution: centrofacial lesions are located in the center of the face (eg, the glabellar, frontal, nasal, zygomatic, upper lip, chin areas), and peripheral lesions manifest on the frontotemporal, preauricular, and mandibular regions.^1,2 There is debate on the categorization of zygomatic (or malar) melasma; some researchers argue it should be categorized independent of other areas, while others include malar melasma in the centrofacial group because of its frequent association with the centrofacial type, especially with glabellar lesions.² Mandibular melasma is rare and occurs mostly in postmenopausal women after intense sun exposure.^1,2 Although the etiopathogenesis of the disease is not clearly known, increased melanogenesis, extracellular matrix alterations, inflammation, and angiogenesis are assumed to play a role.³ Various risk factors such as genetic predisposition, UV radiation (UVR) exposure, pregnancy, thyroid dysfunction, and exogenous hormones (eg, oral contraceptives, hormone replacement therapy) have been identified; phototoxic drugs, anticonvulsants, and some cosmetics also have been implicated.^4,5 Exposure to UVR is thought to be the main triggering environmental factor by inducing both melanin production and oxidative stress.⁵ However, it also has been shown that visible light can induce hyperpigmentation in darker skin types.⁶

The presence of oxidative stress in melasma recently has become an intriguing topic of interest. First, the presence of oxidative stress in the etiopathogenesis of melasma was thought to be based on the effectiveness of antioxidants in treatment. A few studies also have confirmed the presence of oxidative stress in melasma.^7-10 Classically, oxidative stress can be described as a disturbance in the balance between oxidants and antioxidants. Reactive oxygen species (ROS) are highly reactive molecules due to the unpaired electrons in their structure. Although ROS are present at low levels in physiologic conditions and are involved in critical physiologic events, they damage cellular components such as fat, protein, and nucleic acid at high concentrations.⁵

Dynamic thiol/disulfide homeostasis is one of the most important markers of oxidative stress in biological systems. Thiols are organic compounds containing a sulfhydryl (-SH) group. Thiols are considered highly potent antioxidants because they reduce unstable free radicals by donating electrons. They are the first antioxidants to be depleted in an oxidative environment.^11,12 In case of oxidative stress, they transform into reversible forms called disulfide bridges between 2 thiol groups. Disulfide bridges can be reduced back to thiol groups, which is how dynamic thiol/disulfide homeostasis is maintained. Dynamic thiol/disulfide homeostasis is responsible for cellular events such as antioxidant defense, signal transduction, regulation of enzyme function, and apoptosis.^11,12

The aim of this study was to evaluate the presence of oxidative stress in melasma by comparing dynamic thiol/disulfide homeostasis in patients with melasma compared with age- and sex-matched healthy controls.

Materials and Methods

Participants and Eligibility Criteria—We conducted a prospective study in a tertiary-care hospital (Ankara Bilkent City Hospital [Ankara, Turkey]) of patients with melasma who were followed from October 2021 to October 2022 compared with age- and sex-matched healthy volunteers. Ethics committee approval was obtained from Ankara Bilkent City Hospital before the study (E2-21-881)(13.10.2021). Written informed consent was obtained from all participants, and all were older than 18 years. Patients were excluded if there was the presence of any systemic disease or dermatologic disease other than melasma; smoking or alcohol use; any use of vitamins, food supplements, or any medication in the last 3 months; or pregnancy.

Melasma Severity—The modified melasma area and severity index (mMASI) score was used to determine the severity of melasma. The score is calculated from assessments of the darkness of the pigmentation and the percentage of affected area on the face. The mMASI score is the sum of the darkness score (D); area score (A); and separate fixed coefficients for the forehead, as well as the right malar, left malar, and chin regions.¹³ The mMASI score, with a range of 0 to 24, is a reliable and objective marker in the calculation of melasma severity.⁴

Biochemical Analysis of Samples—The 6-cc peripheral fasting venous blood samples obtained from the study participants were centrifuged at 1500 g for 10 minutes, and the separated sera were stored in a freezer at −80 °C until the time of analysis. When the study was completed, the disulfide and thiol values were analyzed. Serum native and total thiol concentrations indicating thiol/disulfide homeostasis were calculated by a new fully automatic colorimetric method developed by Erel and Neselioglu.¹⁴ Using this method, short disulfide bonds are first reduced with sodium borohydride solution to form free-functional thiol groups, and then the unused sodium borohydride is removed using formaldehyde. Finally, all thiol groups are reacted with 5,5’-dithiobis-(2-nitrobenzoic) acid (Ellman reagent), and all thiol groups are detected after reaction with 5,5’-dithiobis-(2-nitrobenzoic) acid. When a disulfide bond (−S−S−) is reduced, 2 thiol groups are formed. For this reason, half of the difference between total thiol (-SH + the amount of thiol formed by the reduction of disulfides) and native thiol (-SH) corresponds to the dynamic disulfide amount (total thiol − native thiol/2).¹⁴

Statistical Analysis—Statistical analysis was performed using SPSS software (version 24.0). Descriptive statistics were presented as numbers and percentages for categorical variables, and numerical variables were presented as mean, SD, median, minimum, maximum, 25th quartile, and 75th quartile. The conformity of the variables to normal distribution was examined using visual (histograms and probability plots) and analytical methods (Kolmogorov-Smirnov/Shapiro-Wilk tests). In pairwise group comparisons for numerical variables, a Mann-Whitney U test was used when normal distribution was not met, and a t test was used when normal distribution was met. The statistical significance level was accepted as P<.05.

Results

Our study included 67 patients with melasma and 41 healthy age- and sex-matched controls. Of the participants with melasma, 60 (89.5%) were female and 7 (10.5%) were male. The control group was similar to the melasma group in terms of sex (87.8% female vs 12.2% male [P=.59]). The mean age (SD) was 33.1 (6.7) years in the melasma group and 31.9 (6.7) years in the control group. Age was similar across both groups (P=.41). All participants were of Asian race, and Fitzpatrick skin types (types II–IV) were similar across both groups.

Fifty-four (80.6%) participants had centrofacial melasma and 13 (19.4%) had mixed-type melasma. The mMASI score ranged from 3 to 20; the mean (SD) mMASI score was 11.28 (3.2). Disease duration ranged from 2 to 72 months; the mean (SD) disease duration was 12.26 (6.3) months. The demographics and clinical characteristics of the study group are shown in eTable 1.

eTable 2 provides a summary of disulfide, native thiol, and total thiol levels, as well as disulfide/native thiol, disulfide/total thiol, and native thiol/total thiol ratios in the study population. Disulfide/native thiol and disulfide/total thiol ratios were higher in melasma patients (Figure 1), whereas the native thiol/total thiol ratio was higher in the control group (P=.025, P=.025, and P=.026, respectively).

All correlations between age, disease duration, and mMASI scores and disulfide, native thiol, and total thiol levels, as well as disulfide/native thiol, disulfide/total thiol, and native thiol/total thiol ratios, are summarized in eTable 3. No significant correlation was observed between age and disease duration and disulfide, native thiol, and total thiol levels or disulfide/native thiol, disulfide/total thiol, and native thiol/total thiol ratios.

We independently assessed whether Fitzpatrick skin types II, III, and IV exhibited distinct levels of oxidative stress in clinical melasma. There were no significant correlations with Fitzpatrick skin type (disulfide/native thiol, P=.25; disulfide/total thiol, P=.19). We further evaluated if the thiol/disulfide parameters were correlated with duration of melasma by dividing the melasma patients into 3 groups (<6 months [n=12], 6–18 months [n=32], >18 months [n=23]), but there was not any significant correlation (disulfide/native thiol, P=.15; disulfide/total thiol, P=.15). We also divided our patients into 3 groups according to age (<27 years [n=14], 27–36 years [n=33], >36 years [n=20]). There was no correlation of the parameters with age (disulfide/native thiol, P=.15; disulfide/total thiol, P=.14).

There was a positive correlation between mMASI score and disulfide, native thiol, and total thiol levels and disulfide/native thiol and disulfide/total thiol ratios, as well as a negative correlation between mMASI score and native thiol/total thiol ratio. The correlations between mMASI scores and disulfide/native thiol and disulfide/total thiol ratios are shown in Figure 2 and eTable 3.

Comment

Melasma is a common condition that may cause psychosocial problems in affected patients and negatively affect quality of life.¹ It occurs in all races but is more common in individuals with darker skin types (eg, Fitzpatrick skin types III and IV). Although melasma is more common in women during reproductive years (50%–70%), it also has been observed in 10% to 30% of men.⁵

Treatment options include topical bleaching agents, chemical peels, and laser therapy, as well as discontinuation of medications that may potentially trigger melasma; use of broad-spectrum sunscreens also is recommended.⁴ Vitamins A, C, and E, as well as niacinamide, are used in the treatment of melasma, especially for their antioxidant properties. The key role of antioxidants in the treatment of melasma supports the importance of oxidative stress in the pathogenesis.⁷ Melasma often is challenging to treat, particularly the mixed or dermal types, due to their stubborn nature. This condition poses a considerable therapeutic challenge for dermatologists.⁴

Oxidative stress and oxidant-antioxidant imbalance previously have been studied in various diseases, but research investigating the presence of oxidative stress in melasma are limited.^7-10 Exposure of the skin to polluted air and intense UVR, as well as some food by-products, cosmetics, and drugs (eg, oral contraceptives), can directly or indirectly cause ROS production in the skin. Reactive oxygen species are thought to be involved in the pathophysiology of melasma by affecting apoptotic pathways and causing cell proliferation. The intermediate heme pathway has pro-oxidant effects and produces ROS and metabolites such as redox-active quinines. Exposure to UVR leads to the generation of ROS, highlighting the role of oxidative stress in the onset of melasma. ⁵

In any cutaneous disease in which oxidative stress plays a role, oxidant and antioxidant levels may be expected to vary both locally and systemically; however, measurement of oxidative stress markers in serum instead of skin is technically and economically more advantageous.⁸ Firstly, serum collection is less invasive and technically simpler than skin biopsies. Drawing blood is a routine procedure that requires minimal specialized equipment and training compared to the extraction and processing of skin samples. Secondly, analyzing serum samples generally is less expensive than processing skin tissue.⁸

In our study, we evaluated dynamic thiol/disulfide homeostasis in serum to investigate the presence of oxidative stress in the setting of melasma. Functional sulfhydryl (-SH) groups in thiols act as substrates for antioxidant enzymes and as free-radical scavengers. They constitute one of the most powerful defense systems against the unwanted effects of ROS. Thiols, which become the main target of ROS under oxidative stress, oxidize with oxidant molecules and form disulfide bridges.¹⁵

Thiol/disulfide homeostasis has been studied many times in dermatologic diseases,^16-19 and the results obtained from these studies are heterogenous depending on the extent of oxidative damage. It has been shown that thiol/disulfide homeostasis plays a role in oxidative stress in conditions such as psoriasis,¹⁷ seborrheic dermatitis,¹¹ atopic dermatitits,¹⁸ and rosacea.¹⁹ In our study, disulfide/native thiol and disulfide/total thiol levels were significantly higher (both P=.025) in the melasma group compared with the control group, which indicates that the thiol/disulfide balance in patients with melasma is shifted to disulfide formation and thiols are oxidized to disulfide bonds in the presence of oxidative stress.

Seçkin et al⁷ evaluated the role of oxidative stress in the pathogenesis of melasma and found that the serum levels of the antioxidants superoxide dismutase and glutathione peroxidase were significantly higher in the patient group compared with the control group (both P<.001). They also found that the levels of nitric oxide (another antioxidant) were increased in the patient group and the levels of protein carbonyl (an oxidative metabolite) were significantly lower (both P<.001). These findings indicated that free-radical damage may be involved in the pathogenesis of melasma.⁷

In a study of 75 patients with melasma, serum levels of the antioxidants melatonin and catalase were significantly (P<.001 and P=.001, respectively) lower in the melasma group compared with the control group, while serum levels of the oxidants protein carbonyl and nitric oxide were significantly higher (P=.002 and P=.001, respectively). No significant correlation was found between oxidative stress parameters and melasma severity.⁸

Choubey et al⁹ found that serum malondialdehyde (an end product of lipid peroxidation), superoxide dismutase, and glutathione peroxidase levels were significantly higher in the melasma group (n=50) compared with the control group (n=50)(all P<.001). In addition, a significant positive correlation (correlation coefficient, +0.307; P<.05) was found between serum malondialdehyde levels and melasma severity. The mean age (SD) of the patients was 32.22 (6.377) years, and the female (n=41) to male (n=9) ratio was 4.55:1. The most common melasma pattern was centrofacial, followed by malar.⁹

In a study with 50 melasma patients and 50 controls, Rahimi et al¹⁰ examined bilirubin and uric acid levels, which are major extracellular antioxidants. The mean age (SD) at disease onset was 32.6 (6.7) years, and the mean MASI score (SD) was 18.1 (9). Serum bilirubin levels were found to be higher in the melasma group than in the control group and were correlated with disease severity. No significant difference in uric acid levels was found between the groups, and no correlation was found between MASI score and bilirubin and uric acid levels.¹⁰

In our study, the melasma group was similar to those in other reportsin the literature regarding gender distribution, mean age, and melasma pattern.^7-10 Additionally, the correlation of mMASI score with disulfide/native thiol and disulfide/total thiol values in the melasma group suggested that oxidative stress also is correlated with melasma severity.

Thiol-based treatments such as n-acetyl cysteine, which contains a thiol compound, may be helpful in melasma.²⁰ In a double-blind, placebo-controlled study, topical n-acetyl cysteine combined with hydroquinone 2% was used in 10 female patients with melasma. Mild to strong bleaching of the skin was observed in 90% (9/10) of the patients.²¹ Systemic use of n-acetyl cysteine in melasma also may be a potential research topic.

Major limitations of our study were the small sample size and lack of measurement of oxidative stress parameters in the skin concurrently with serum.

Conclusion

In our study, the presence of oxidative stress in melasma was demonstrated by evaluating thiol/disulfide homeostasis—one of the strongest markers of oxidative stress. Oxidative stress also correlated with melasma disease severity in our analysis. The data obtained in this study may contribute to understanding the etiopathogenesis of melasma and may open new horizons in treatment; however, more comprehensive studies should be conducted to support our findings.

Melasma is an acquired hyperpigmentation disorder characterized by irregular brown macules and patches that usually appear on sun-exposed areas of the skin. The term melasma originates from the Greek word melas meaning black.¹ Facial melasma is divided into 2 groups according to its clinical distribution: centrofacial lesions are located in the center of the face (eg, the glabellar, frontal, nasal, zygomatic, upper lip, chin areas), and peripheral lesions manifest on the frontotemporal, preauricular, and mandibular regions.^1,2 There is debate on the categorization of zygomatic (or malar) melasma; some researchers argue it should be categorized independent of other areas, while others include malar melasma in the centrofacial group because of its frequent association with the centrofacial type, especially with glabellar lesions.² Mandibular melasma is rare and occurs mostly in postmenopausal women after intense sun exposure.^1,2 Although the etiopathogenesis of the disease is not clearly known, increased melanogenesis, extracellular matrix alterations, inflammation, and angiogenesis are assumed to play a role.³ Various risk factors such as genetic predisposition, UV radiation (UVR) exposure, pregnancy, thyroid dysfunction, and exogenous hormones (eg, oral contraceptives, hormone replacement therapy) have been identified; phototoxic drugs, anticonvulsants, and some cosmetics also have been implicated.^4,5 Exposure to UVR is thought to be the main triggering environmental factor by inducing both melanin production and oxidative stress.⁵ However, it also has been shown that visible light can induce hyperpigmentation in darker skin types.⁶

The presence of oxidative stress in melasma recently has become an intriguing topic of interest. First, the presence of oxidative stress in the etiopathogenesis of melasma was thought to be based on the effectiveness of antioxidants in treatment. A few studies also have confirmed the presence of oxidative stress in melasma.^7-10 Classically, oxidative stress can be described as a disturbance in the balance between oxidants and antioxidants. Reactive oxygen species (ROS) are highly reactive molecules due to the unpaired electrons in their structure. Although ROS are present at low levels in physiologic conditions and are involved in critical physiologic events, they damage cellular components such as fat, protein, and nucleic acid at high concentrations.⁵

Dynamic thiol/disulfide homeostasis is one of the most important markers of oxidative stress in biological systems. Thiols are organic compounds containing a sulfhydryl (-SH) group. Thiols are considered highly potent antioxidants because they reduce unstable free radicals by donating electrons. They are the first antioxidants to be depleted in an oxidative environment.^11,12 In case of oxidative stress, they transform into reversible forms called disulfide bridges between 2 thiol groups. Disulfide bridges can be reduced back to thiol groups, which is how dynamic thiol/disulfide homeostasis is maintained. Dynamic thiol/disulfide homeostasis is responsible for cellular events such as antioxidant defense, signal transduction, regulation of enzyme function, and apoptosis.^11,12

The aim of this study was to evaluate the presence of oxidative stress in melasma by comparing dynamic thiol/disulfide homeostasis in patients with melasma compared with age- and sex-matched healthy controls.

Materials and Methods

Participants and Eligibility Criteria—We conducted a prospective study in a tertiary-care hospital (Ankara Bilkent City Hospital [Ankara, Turkey]) of patients with melasma who were followed from October 2021 to October 2022 compared with age- and sex-matched healthy volunteers. Ethics committee approval was obtained from Ankara Bilkent City Hospital before the study (E2-21-881)(13.10.2021). Written informed consent was obtained from all participants, and all were older than 18 years. Patients were excluded if there was the presence of any systemic disease or dermatologic disease other than melasma; smoking or alcohol use; any use of vitamins, food supplements, or any medication in the last 3 months; or pregnancy.

Melasma Severity—The modified melasma area and severity index (mMASI) score was used to determine the severity of melasma. The score is calculated from assessments of the darkness of the pigmentation and the percentage of affected area on the face. The mMASI score is the sum of the darkness score (D); area score (A); and separate fixed coefficients for the forehead, as well as the right malar, left malar, and chin regions.¹³ The mMASI score, with a range of 0 to 24, is a reliable and objective marker in the calculation of melasma severity.⁴

Biochemical Analysis of Samples—The 6-cc peripheral fasting venous blood samples obtained from the study participants were centrifuged at 1500 g for 10 minutes, and the separated sera were stored in a freezer at −80 °C until the time of analysis. When the study was completed, the disulfide and thiol values were analyzed. Serum native and total thiol concentrations indicating thiol/disulfide homeostasis were calculated by a new fully automatic colorimetric method developed by Erel and Neselioglu.¹⁴ Using this method, short disulfide bonds are first reduced with sodium borohydride solution to form free-functional thiol groups, and then the unused sodium borohydride is removed using formaldehyde. Finally, all thiol groups are reacted with 5,5’-dithiobis-(2-nitrobenzoic) acid (Ellman reagent), and all thiol groups are detected after reaction with 5,5’-dithiobis-(2-nitrobenzoic) acid. When a disulfide bond (−S−S−) is reduced, 2 thiol groups are formed. For this reason, half of the difference between total thiol (-SH + the amount of thiol formed by the reduction of disulfides) and native thiol (-SH) corresponds to the dynamic disulfide amount (total thiol − native thiol/2).¹⁴

Statistical Analysis—Statistical analysis was performed using SPSS software (version 24.0). Descriptive statistics were presented as numbers and percentages for categorical variables, and numerical variables were presented as mean, SD, median, minimum, maximum, 25th quartile, and 75th quartile. The conformity of the variables to normal distribution was examined using visual (histograms and probability plots) and analytical methods (Kolmogorov-Smirnov/Shapiro-Wilk tests). In pairwise group comparisons for numerical variables, a Mann-Whitney U test was used when normal distribution was not met, and a t test was used when normal distribution was met. The statistical significance level was accepted as P<.05.

Results

Our study included 67 patients with melasma and 41 healthy age- and sex-matched controls. Of the participants with melasma, 60 (89.5%) were female and 7 (10.5%) were male. The control group was similar to the melasma group in terms of sex (87.8% female vs 12.2% male [P=.59]). The mean age (SD) was 33.1 (6.7) years in the melasma group and 31.9 (6.7) years in the control group. Age was similar across both groups (P=.41). All participants were of Asian race, and Fitzpatrick skin types (types II–IV) were similar across both groups.

Fifty-four (80.6%) participants had centrofacial melasma and 13 (19.4%) had mixed-type melasma. The mMASI score ranged from 3 to 20; the mean (SD) mMASI score was 11.28 (3.2). Disease duration ranged from 2 to 72 months; the mean (SD) disease duration was 12.26 (6.3) months. The demographics and clinical characteristics of the study group are shown in eTable 1.

eTable 2 provides a summary of disulfide, native thiol, and total thiol levels, as well as disulfide/native thiol, disulfide/total thiol, and native thiol/total thiol ratios in the study population. Disulfide/native thiol and disulfide/total thiol ratios were higher in melasma patients (Figure 1), whereas the native thiol/total thiol ratio was higher in the control group (P=.025, P=.025, and P=.026, respectively).

All correlations between age, disease duration, and mMASI scores and disulfide, native thiol, and total thiol levels, as well as disulfide/native thiol, disulfide/total thiol, and native thiol/total thiol ratios, are summarized in eTable 3. No significant correlation was observed between age and disease duration and disulfide, native thiol, and total thiol levels or disulfide/native thiol, disulfide/total thiol, and native thiol/total thiol ratios.

We independently assessed whether Fitzpatrick skin types II, III, and IV exhibited distinct levels of oxidative stress in clinical melasma. There were no significant correlations with Fitzpatrick skin type (disulfide/native thiol, P=.25; disulfide/total thiol, P=.19). We further evaluated if the thiol/disulfide parameters were correlated with duration of melasma by dividing the melasma patients into 3 groups (<6 months [n=12], 6–18 months [n=32], >18 months [n=23]), but there was not any significant correlation (disulfide/native thiol, P=.15; disulfide/total thiol, P=.15). We also divided our patients into 3 groups according to age (<27 years [n=14], 27–36 years [n=33], >36 years [n=20]). There was no correlation of the parameters with age (disulfide/native thiol, P=.15; disulfide/total thiol, P=.14).

There was a positive correlation between mMASI score and disulfide, native thiol, and total thiol levels and disulfide/native thiol and disulfide/total thiol ratios, as well as a negative correlation between mMASI score and native thiol/total thiol ratio. The correlations between mMASI scores and disulfide/native thiol and disulfide/total thiol ratios are shown in Figure 2 and eTable 3.

Comment

Melasma is a common condition that may cause psychosocial problems in affected patients and negatively affect quality of life.¹ It occurs in all races but is more common in individuals with darker skin types (eg, Fitzpatrick skin types III and IV). Although melasma is more common in women during reproductive years (50%–70%), it also has been observed in 10% to 30% of men.⁵

Treatment options include topical bleaching agents, chemical peels, and laser therapy, as well as discontinuation of medications that may potentially trigger melasma; use of broad-spectrum sunscreens also is recommended.⁴ Vitamins A, C, and E, as well as niacinamide, are used in the treatment of melasma, especially for their antioxidant properties. The key role of antioxidants in the treatment of melasma supports the importance of oxidative stress in the pathogenesis.⁷ Melasma often is challenging to treat, particularly the mixed or dermal types, due to their stubborn nature. This condition poses a considerable therapeutic challenge for dermatologists.⁴

Oxidative stress and oxidant-antioxidant imbalance previously have been studied in various diseases, but research investigating the presence of oxidative stress in melasma are limited.^7-10 Exposure of the skin to polluted air and intense UVR, as well as some food by-products, cosmetics, and drugs (eg, oral contraceptives), can directly or indirectly cause ROS production in the skin. Reactive oxygen species are thought to be involved in the pathophysiology of melasma by affecting apoptotic pathways and causing cell proliferation. The intermediate heme pathway has pro-oxidant effects and produces ROS and metabolites such as redox-active quinines. Exposure to UVR leads to the generation of ROS, highlighting the role of oxidative stress in the onset of melasma. ⁵

In any cutaneous disease in which oxidative stress plays a role, oxidant and antioxidant levels may be expected to vary both locally and systemically; however, measurement of oxidative stress markers in serum instead of skin is technically and economically more advantageous.⁸ Firstly, serum collection is less invasive and technically simpler than skin biopsies. Drawing blood is a routine procedure that requires minimal specialized equipment and training compared to the extraction and processing of skin samples. Secondly, analyzing serum samples generally is less expensive than processing skin tissue.⁸

In our study, we evaluated dynamic thiol/disulfide homeostasis in serum to investigate the presence of oxidative stress in the setting of melasma. Functional sulfhydryl (-SH) groups in thiols act as substrates for antioxidant enzymes and as free-radical scavengers. They constitute one of the most powerful defense systems against the unwanted effects of ROS. Thiols, which become the main target of ROS under oxidative stress, oxidize with oxidant molecules and form disulfide bridges.¹⁵

Thiol/disulfide homeostasis has been studied many times in dermatologic diseases,^16-19 and the results obtained from these studies are heterogenous depending on the extent of oxidative damage. It has been shown that thiol/disulfide homeostasis plays a role in oxidative stress in conditions such as psoriasis,¹⁷ seborrheic dermatitis,¹¹ atopic dermatitits,¹⁸ and rosacea.¹⁹ In our study, disulfide/native thiol and disulfide/total thiol levels were significantly higher (both P=.025) in the melasma group compared with the control group, which indicates that the thiol/disulfide balance in patients with melasma is shifted to disulfide formation and thiols are oxidized to disulfide bonds in the presence of oxidative stress.

Seçkin et al⁷ evaluated the role of oxidative stress in the pathogenesis of melasma and found that the serum levels of the antioxidants superoxide dismutase and glutathione peroxidase were significantly higher in the patient group compared with the control group (both P<.001). They also found that the levels of nitric oxide (another antioxidant) were increased in the patient group and the levels of protein carbonyl (an oxidative metabolite) were significantly lower (both P<.001). These findings indicated that free-radical damage may be involved in the pathogenesis of melasma.⁷

In a study of 75 patients with melasma, serum levels of the antioxidants melatonin and catalase were significantly (P<.001 and P=.001, respectively) lower in the melasma group compared with the control group, while serum levels of the oxidants protein carbonyl and nitric oxide were significantly higher (P=.002 and P=.001, respectively). No significant correlation was found between oxidative stress parameters and melasma severity.⁸

Choubey et al⁹ found that serum malondialdehyde (an end product of lipid peroxidation), superoxide dismutase, and glutathione peroxidase levels were significantly higher in the melasma group (n=50) compared with the control group (n=50)(all P<.001). In addition, a significant positive correlation (correlation coefficient, +0.307; P<.05) was found between serum malondialdehyde levels and melasma severity. The mean age (SD) of the patients was 32.22 (6.377) years, and the female (n=41) to male (n=9) ratio was 4.55:1. The most common melasma pattern was centrofacial, followed by malar.⁹

In a study with 50 melasma patients and 50 controls, Rahimi et al¹⁰ examined bilirubin and uric acid levels, which are major extracellular antioxidants. The mean age (SD) at disease onset was 32.6 (6.7) years, and the mean MASI score (SD) was 18.1 (9). Serum bilirubin levels were found to be higher in the melasma group than in the control group and were correlated with disease severity. No significant difference in uric acid levels was found between the groups, and no correlation was found between MASI score and bilirubin and uric acid levels.¹⁰

In our study, the melasma group was similar to those in other reportsin the literature regarding gender distribution, mean age, and melasma pattern.^7-10 Additionally, the correlation of mMASI score with disulfide/native thiol and disulfide/total thiol values in the melasma group suggested that oxidative stress also is correlated with melasma severity.

Thiol-based treatments such as n-acetyl cysteine, which contains a thiol compound, may be helpful in melasma.²⁰ In a double-blind, placebo-controlled study, topical n-acetyl cysteine combined with hydroquinone 2% was used in 10 female patients with melasma. Mild to strong bleaching of the skin was observed in 90% (9/10) of the patients.²¹ Systemic use of n-acetyl cysteine in melasma also may be a potential research topic.

Major limitations of our study were the small sample size and lack of measurement of oxidative stress parameters in the skin concurrently with serum.

Conclusion

In our study, the presence of oxidative stress in melasma was demonstrated by evaluating thiol/disulfide homeostasis—one of the strongest markers of oxidative stress. Oxidative stress also correlated with melasma disease severity in our analysis. The data obtained in this study may contribute to understanding the etiopathogenesis of melasma and may open new horizons in treatment; however, more comprehensive studies should be conducted to support our findings.

Practice Gap

The Wood lamp commonly is used as a diagnostic tool for pigmentary skin conditions (eg, vitiligo) or skin conditions that exhibit fluorescence (eg, erythrasma).¹ Recently, its diagnostic efficacy has extended to scabies, in which it unveils a distinctive wavy, bluish-white, linear fluorescence upon illumination.²

Functionally, the Wood lamp operates by subjecting phosphors to UV light within the wavelength range of 320 to 400 nm, inducing fluorescence in substances such as collagen and elastin. In the context of vitiligo, this process manifests as a preferential chalk white fluorescence in areas lacking melanin.¹

Despite its demonstrated effectiveness, the Wood lamp is not without limitations. It comes with a notable financial investment ranging from $70 to $500, requires periodic maintenance such as light bulb replacements, and can be unwieldy.³ Furthermore, its reliance on a power source poses a challenge in settings where immediate access to convenient power outlets is limited, such as inpatient and rural dermatology clinics. These limitations underscore the need for alternative solutions and innovations to address challenges and ensure accessibility in diverse health care environments.

The Tools

Free smartphone applications (apps), such as Ultraviolet Light-UV Lamp by AppBrain or Blacklight UV Light Simulator by That Smile, can simulate UV light and functionally serve as a Wood lamp.

The Technique

UV light apps use LED or organic LED screen pixels to emit a blue light equivalent at 467 nm.⁴ Although these apps are not designed specifically for dermatologic uses, they are mostly free, widely available for Android and iPhone users, and portable. Importantly, they can demonstrate good performance in visualizing vitiligo, as shown in Figure 1—albeit perhaps not reaching the same level as the Wood lamp (Figure 2).

Because these UV light apps are not regulated and their efficacy for medical use has not been firmly established, the Wood lamp remains the gold standard. Therefore, we propose the use of UV light apps in situations when a Wood lamp is not available or convenient, such as in rural, inpatient, or international health care settings.

Practice Implications

Exploring and adopting these free alternatives can contribute to improved accessibility and diagnostic capabilities in diverse health care environments, particularly for communities facing financial constraints. Continued research and validation of these apps in clinical settings will be essential to establish their reliability and effectiveness in enhancing diagnostic practices.

Practice Gap

The Wood lamp commonly is used as a diagnostic tool for pigmentary skin conditions (eg, vitiligo) or skin conditions that exhibit fluorescence (eg, erythrasma).¹ Recently, its diagnostic efficacy has extended to scabies, in which it unveils a distinctive wavy, bluish-white, linear fluorescence upon illumination.²

Functionally, the Wood lamp operates by subjecting phosphors to UV light within the wavelength range of 320 to 400 nm, inducing fluorescence in substances such as collagen and elastin. In the context of vitiligo, this process manifests as a preferential chalk white fluorescence in areas lacking melanin.¹

Despite its demonstrated effectiveness, the Wood lamp is not without limitations. It comes with a notable financial investment ranging from $70 to $500, requires periodic maintenance such as light bulb replacements, and can be unwieldy.³ Furthermore, its reliance on a power source poses a challenge in settings where immediate access to convenient power outlets is limited, such as inpatient and rural dermatology clinics. These limitations underscore the need for alternative solutions and innovations to address challenges and ensure accessibility in diverse health care environments.

The Tools

Free smartphone applications (apps), such as Ultraviolet Light-UV Lamp by AppBrain or Blacklight UV Light Simulator by That Smile, can simulate UV light and functionally serve as a Wood lamp.

The Technique

UV light apps use LED or organic LED screen pixels to emit a blue light equivalent at 467 nm.⁴ Although these apps are not designed specifically for dermatologic uses, they are mostly free, widely available for Android and iPhone users, and portable. Importantly, they can demonstrate good performance in visualizing vitiligo, as shown in Figure 1—albeit perhaps not reaching the same level as the Wood lamp (Figure 2).

Because these UV light apps are not regulated and their efficacy for medical use has not been firmly established, the Wood lamp remains the gold standard. Therefore, we propose the use of UV light apps in situations when a Wood lamp is not available or convenient, such as in rural, inpatient, or international health care settings.

Practice Implications

Exploring and adopting these free alternatives can contribute to improved accessibility and diagnostic capabilities in diverse health care environments, particularly for communities facing financial constraints. Continued research and validation of these apps in clinical settings will be essential to establish their reliability and effectiveness in enhancing diagnostic practices.

Practice Gap

The Wood lamp commonly is used as a diagnostic tool for pigmentary skin conditions (eg, vitiligo) or skin conditions that exhibit fluorescence (eg, erythrasma).¹ Recently, its diagnostic efficacy has extended to scabies, in which it unveils a distinctive wavy, bluish-white, linear fluorescence upon illumination.²

Functionally, the Wood lamp operates by subjecting phosphors to UV light within the wavelength range of 320 to 400 nm, inducing fluorescence in substances such as collagen and elastin. In the context of vitiligo, this process manifests as a preferential chalk white fluorescence in areas lacking melanin.¹

Despite its demonstrated effectiveness, the Wood lamp is not without limitations. It comes with a notable financial investment ranging from $70 to $500, requires periodic maintenance such as light bulb replacements, and can be unwieldy.³ Furthermore, its reliance on a power source poses a challenge in settings where immediate access to convenient power outlets is limited, such as inpatient and rural dermatology clinics. These limitations underscore the need for alternative solutions and innovations to address challenges and ensure accessibility in diverse health care environments.

The Tools

Free smartphone applications (apps), such as Ultraviolet Light-UV Lamp by AppBrain or Blacklight UV Light Simulator by That Smile, can simulate UV light and functionally serve as a Wood lamp.

The Technique

UV light apps use LED or organic LED screen pixels to emit a blue light equivalent at 467 nm.⁴ Although these apps are not designed specifically for dermatologic uses, they are mostly free, widely available for Android and iPhone users, and portable. Importantly, they can demonstrate good performance in visualizing vitiligo, as shown in Figure 1—albeit perhaps not reaching the same level as the Wood lamp (Figure 2).

Because these UV light apps are not regulated and their efficacy for medical use has not been firmly established, the Wood lamp remains the gold standard. Therefore, we propose the use of UV light apps in situations when a Wood lamp is not available or convenient, such as in rural, inpatient, or international health care settings.

Practice Implications

Exploring and adopting these free alternatives can contribute to improved accessibility and diagnostic capabilities in diverse health care environments, particularly for communities facing financial constraints. Continued research and validation of these apps in clinical settings will be essential to establish their reliability and effectiveness in enhancing diagnostic practices.