Pigmentation Disorders

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).

bufrish

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).

bufrish

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).

bufrish

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

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pimifrumafricrijeuamostoshimubarocrobiwegospogotrikesheclouoswivuvuhonucohasuthujestaspimocradifrutrekuthubrebrocrospichukalifrahalaceputhalacruswospahapheswi

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.

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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

kocradrupathedriphuhatriwebripudrudrimechametehosothahapedaslihebulalakathapuretumod

pimifrumafricrijeuamostoshimubarocrobiwegospogotrikesheclouoswivuvuhonucohasuthujestaspimocradifrutrekuthubrebrocrospichukalifrahalaceputhalacruswospahapheswi

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.

gowribriphosaslaswarucusparucrocubiseruclajowrothageclumaslabotenochukanethepronechaphijiuuclakiwruslaclusleshistospasophojephu

modrawespospuvuravachacrojogistewowospuwuviphohastos

ph

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

kocradrupathedriphuhatriwebripudrudrimechametehosothahapedaslihebulalakathapuretumod

pimifrumafricrijeuamostoshimubarocrobiwegospogotrikesheclouoswivuvuhonucohasuthujestaspimocradifrutrekuthubrebrocrospichukalifrahalaceputhalacruswospahapheswi

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.

gowribriphosaslaswarucusparucrocubiseruclajowrothageclumaslabotenochukanethepronechaphijiuuclakiwruslaclusleshistospasophojephu

modrawespospuvuravachacrojogistewowospuwuviphohastos

ph

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).

ruvujepachanunaspukustunisloseslopripraspahelothulathurisikibralutauipheswapipheuispovestitredrachoclechujefrachiwibamuwrobepenithusabrovosuwr

trapreuechikibrefrithashaslotadrouushowepafraceshilesugastedrigicloswaphewuspasperecledosteratrunidrucludamagubupricluswiswehathiswogasephobrejuspedrijahastothopresosluvurogawafribra

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).

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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).

ruvujepachanunaspukustunisloseslopripraspahelothulathurisikibralutauipheswapipheuispovestitredrachoclechujefrachiwibamuwrobepenithusabrovosuwr

trapreuechikibrefrithashaslotadrouushowepafraceshilesugastedrigicloswaphewuspasperecledosteratrunidrucludamagubupricluswiswehathiswogasephobrejuspedrijahastothopresosluvurogawafribra

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.

To the Editor:

Langerhans cell histiocytosis (LCH) is a rare inflammatory neoplasia caused by accumulation of clonal Langerhans cells in 1 or more organs. The clinical spectrum is diverse, ranging from mild, single-organ involvement that may resolve spontaneously to severe progressive multisystem disease that can be fatal. It is most prevalent in children, affecting an estimated 4 to 5 children for every 1 million annually, with male predominance.¹ The pathogenesis is driven by activating mutations in the mitogen-activated protein kinase pathway, with the BRAF V600E mutation detected in most LCH patients, resulting in proliferation of pathologic Langerhans cells and dysregulated expression of inflammatory cytokines in LCH lesions.² A biopsy of lesional tissue is required for definitive diagnosis. Histopathology reveals a mixed inflammatory infiltrate and characteristic mononuclear cells with reniform nuclei that are positive for CD1a and CD207 proteins on immunohistochemical staining.³

Langerhans cell histiocytosis is categorized by the extent of organ involvement. It commonly affects the bones, skin, pituitary gland, liver, lungs, bone marrow, and lymph nodes.⁴ Single-system LCH involves a single organ with unifocal or multifocal lesions; multisystem LCH involves 2 or more organs and has a worse prognosis if risk organs (eg, liver, spleen, bone marrow) are involved.⁴

Skin lesions are reported in more than half of LCH cases and are the most common initial manifestation in patients younger than 2 years.⁴ Cutaneous findings are highly variable, which poses a diagnostic challenge. Common morphologies include erythematous papules, pustules, papulovesicles, scaly plaques, erosions, and petechiae. Lesions can be solitary or widespread and favor the trunk, head, and face.⁴ We describe an atypical case of hypopigmented cutaneous LCH and review the literature on this morphology in patients with skin of color.

A 7-month-old Hispanic male infant who was otherwise healthy presented with numerous hypopigmented macules and pink papules on the trunk and groin that had progressed since birth. A review of systems was unremarkable. Physical examination revealed 1- to 3-mm, discrete, hypopigmented macules intermixed with 1- to 2-mm pearly pink papules scattered on the back, chest, abdomen, and inguinal folds (Figure 1). Some lesions appeared koebnerized; however, the parents denied a history of scratching or trauma.

Histopathology of a lesion in the inguinal fold showed aggregates of mononuclear cells with reniform nuclei and abundant amphophilic cytoplasm in the papillary dermis, with focal extension into the epidermis. Scattered eosinophils and multinucleated giant cells were present in the dermal inflammatory infiltrate (Figure 2). Immunohistochemical staining was positive for CD1a (Figure 3) and S-100 protein (Figure 4). Although epidermal Langerhans cell collections also can be seen in allergic contact dermatitis,⁵ predominant involvement of the papillary dermis and the presence of multinucleated giant cells are characteristic of LCH.⁴ Given these findings, which were consistent with LCH, the dermatopathology deemed BRAF V600E immunostaining unnecessary for diagnostic purposes.

spudrichacrukap

slecospathocunaprubritrilulapriwrecuwonuclukogihadrinarobuwrofrophehisteprethituniclodichadetrimipiprocludeuastethipesteswochestophucricrumasigospiphadreshovucrinu

biclarehiprosticinalifroslestostapretuda

luludalecupacrimes

thekonaphechaswamuclawiproswochospostibrufrihuwrocloworunufradrakidospefraphiuechehoprithojuslowewrucothiphatrewr

The patient was referred to the hematology and oncology department to undergo thorough evaluation for extracutaneous involvement. The workup included a complete blood cell count, liver function testing, electrolyte assessment, skeletal survey, chest radiography, and ultrasonography of the liver and spleen. All results were negative, suggesting a diagnosis of single-system cutaneous LCH.

Three months later, the patient presented to dermatology with spontaneous regression of all skin lesions. Continued follow-up—every 6 months for 5 years—was recommended to monitor for disease recurrence or progression to multisystem disease.

Cutaneous LCH is a clinically heterogeneous disease with the potential for multisystem involvement and long-term sequelae; therefore, timely diagnosis is paramount to optimize outcomes. However, delayed diagnosis is common because of the spectrum of skin findings that can mimic common pediatric dermatoses, such as seborrheic dermatitis, atopic dermatitis, and diaper dermatitis.⁴ In one study, the median time from onset of skin lesions to diagnostic biopsy was longer than 3 months (maximum, 5 years).⁶ Our patient was referred to dermatology 7 months after onset of hypopigmented macules, a rarely reported cutaneous manifestation of LCH.

A PubMed search of articles indexed for MEDLINE from 1994 to 2019 using the terms Langerhans cell histiocytotis and hypopigmented yielded 17 cases of LCH presenting as hypopigmented skin lesions (Table).^7-22 All cases occurred in patients with skin of color (ie, patients of Asian, Hispanic, or African descent). Hypopigmented macules were the only cutaneous manifestation in 10 (59%) cases. Lesions most commonly were distributed on the trunk (16/17 [94%]) and extremities (8/17 [47%]). The median age of onset was 1 month; 76% (13/17) of patients developed skin lesions before 1 year of age, indicating that this morphology may be more common in newborns. In most patients, the diagnosis was single-system cutaneous LCH; they exhibited spontaneous regression by 8 months of age on average, suggesting that this variant may be associated with a better prognosis. Mori and colleagues²¹ hypothesized that hypopigmented lesions may represent the resolving stage of active LCH based on histopathologic findings of dermal pallor and fibrosis in a hypopigmented LCH lesion. However, systemic involvement was reported in 7 cases of hypopigmented LCH, highlighting the importance of assessing for multisystem disease regardless of cutaneous morphology.²¹Langerhans cell histiocytosis should be considered in the differential diagnosis when evaluating hypopigmented skin eruptions in infants with darker skin types. Prompt diagnosis of this atypical variant requires a higher index of suspicion because of its rarity and the polymorphic nature of cutaneous LCH. This morphology may go undiagnosed in the setting of mild or spontaneously resolving disease; notwithstanding, accurate diagnosis and longitudinal surveillance are necessary given the potential for progressive systemic involvement.

To the Editor:

Langerhans cell histiocytosis (LCH) is a rare inflammatory neoplasia caused by accumulation of clonal Langerhans cells in 1 or more organs. The clinical spectrum is diverse, ranging from mild, single-organ involvement that may resolve spontaneously to severe progressive multisystem disease that can be fatal. It is most prevalent in children, affecting an estimated 4 to 5 children for every 1 million annually, with male predominance.¹ The pathogenesis is driven by activating mutations in the mitogen-activated protein kinase pathway, with the BRAF V600E mutation detected in most LCH patients, resulting in proliferation of pathologic Langerhans cells and dysregulated expression of inflammatory cytokines in LCH lesions.² A biopsy of lesional tissue is required for definitive diagnosis. Histopathology reveals a mixed inflammatory infiltrate and characteristic mononuclear cells with reniform nuclei that are positive for CD1a and CD207 proteins on immunohistochemical staining.³

Langerhans cell histiocytosis is categorized by the extent of organ involvement. It commonly affects the bones, skin, pituitary gland, liver, lungs, bone marrow, and lymph nodes.⁴ Single-system LCH involves a single organ with unifocal or multifocal lesions; multisystem LCH involves 2 or more organs and has a worse prognosis if risk organs (eg, liver, spleen, bone marrow) are involved.⁴

Skin lesions are reported in more than half of LCH cases and are the most common initial manifestation in patients younger than 2 years.⁴ Cutaneous findings are highly variable, which poses a diagnostic challenge. Common morphologies include erythematous papules, pustules, papulovesicles, scaly plaques, erosions, and petechiae. Lesions can be solitary or widespread and favor the trunk, head, and face.⁴ We describe an atypical case of hypopigmented cutaneous LCH and review the literature on this morphology in patients with skin of color.

A 7-month-old Hispanic male infant who was otherwise healthy presented with numerous hypopigmented macules and pink papules on the trunk and groin that had progressed since birth. A review of systems was unremarkable. Physical examination revealed 1- to 3-mm, discrete, hypopigmented macules intermixed with 1- to 2-mm pearly pink papules scattered on the back, chest, abdomen, and inguinal folds (Figure 1). Some lesions appeared koebnerized; however, the parents denied a history of scratching or trauma.

Histopathology of a lesion in the inguinal fold showed aggregates of mononuclear cells with reniform nuclei and abundant amphophilic cytoplasm in the papillary dermis, with focal extension into the epidermis. Scattered eosinophils and multinucleated giant cells were present in the dermal inflammatory infiltrate (Figure 2). Immunohistochemical staining was positive for CD1a (Figure 3) and S-100 protein (Figure 4). Although epidermal Langerhans cell collections also can be seen in allergic contact dermatitis,⁵ predominant involvement of the papillary dermis and the presence of multinucleated giant cells are characteristic of LCH.⁴ Given these findings, which were consistent with LCH, the dermatopathology deemed BRAF V600E immunostaining unnecessary for diagnostic purposes.

spudrichacrukap

slecospathocunaprubritrilulapriwrecuwonuclukogihadrinarobuwrofrophehisteprethituniclodichadetrimipiprocludeuastethipesteswochestophucricrumasigospiphadreshovucrinu

biclarehiprosticinalifroslestostapretuda

luludalecupacrimes

thekonaphechaswamuclawiproswochospostibrufrihuwrocloworunufradrakidospefraphiuechehoprithojuslowewrucothiphatrewr

The patient was referred to the hematology and oncology department to undergo thorough evaluation for extracutaneous involvement. The workup included a complete blood cell count, liver function testing, electrolyte assessment, skeletal survey, chest radiography, and ultrasonography of the liver and spleen. All results were negative, suggesting a diagnosis of single-system cutaneous LCH.

Three months later, the patient presented to dermatology with spontaneous regression of all skin lesions. Continued follow-up—every 6 months for 5 years—was recommended to monitor for disease recurrence or progression to multisystem disease.

Cutaneous LCH is a clinically heterogeneous disease with the potential for multisystem involvement and long-term sequelae; therefore, timely diagnosis is paramount to optimize outcomes. However, delayed diagnosis is common because of the spectrum of skin findings that can mimic common pediatric dermatoses, such as seborrheic dermatitis, atopic dermatitis, and diaper dermatitis.⁴ In one study, the median time from onset of skin lesions to diagnostic biopsy was longer than 3 months (maximum, 5 years).⁶ Our patient was referred to dermatology 7 months after onset of hypopigmented macules, a rarely reported cutaneous manifestation of LCH.

A PubMed search of articles indexed for MEDLINE from 1994 to 2019 using the terms Langerhans cell histiocytotis and hypopigmented yielded 17 cases of LCH presenting as hypopigmented skin lesions (Table).^7-22 All cases occurred in patients with skin of color (ie, patients of Asian, Hispanic, or African descent). Hypopigmented macules were the only cutaneous manifestation in 10 (59%) cases. Lesions most commonly were distributed on the trunk (16/17 [94%]) and extremities (8/17 [47%]). The median age of onset was 1 month; 76% (13/17) of patients developed skin lesions before 1 year of age, indicating that this morphology may be more common in newborns. In most patients, the diagnosis was single-system cutaneous LCH; they exhibited spontaneous regression by 8 months of age on average, suggesting that this variant may be associated with a better prognosis. Mori and colleagues²¹ hypothesized that hypopigmented lesions may represent the resolving stage of active LCH based on histopathologic findings of dermal pallor and fibrosis in a hypopigmented LCH lesion. However, systemic involvement was reported in 7 cases of hypopigmented LCH, highlighting the importance of assessing for multisystem disease regardless of cutaneous morphology.²¹Langerhans cell histiocytosis should be considered in the differential diagnosis when evaluating hypopigmented skin eruptions in infants with darker skin types. Prompt diagnosis of this atypical variant requires a higher index of suspicion because of its rarity and the polymorphic nature of cutaneous LCH. This morphology may go undiagnosed in the setting of mild or spontaneously resolving disease; notwithstanding, accurate diagnosis and longitudinal surveillance are necessary given the potential for progressive systemic involvement.

To the Editor:

Langerhans cell histiocytosis (LCH) is a rare inflammatory neoplasia caused by accumulation of clonal Langerhans cells in 1 or more organs. The clinical spectrum is diverse, ranging from mild, single-organ involvement that may resolve spontaneously to severe progressive multisystem disease that can be fatal. It is most prevalent in children, affecting an estimated 4 to 5 children for every 1 million annually, with male predominance.¹ The pathogenesis is driven by activating mutations in the mitogen-activated protein kinase pathway, with the BRAF V600E mutation detected in most LCH patients, resulting in proliferation of pathologic Langerhans cells and dysregulated expression of inflammatory cytokines in LCH lesions.² A biopsy of lesional tissue is required for definitive diagnosis. Histopathology reveals a mixed inflammatory infiltrate and characteristic mononuclear cells with reniform nuclei that are positive for CD1a and CD207 proteins on immunohistochemical staining.³

Langerhans cell histiocytosis is categorized by the extent of organ involvement. It commonly affects the bones, skin, pituitary gland, liver, lungs, bone marrow, and lymph nodes.⁴ Single-system LCH involves a single organ with unifocal or multifocal lesions; multisystem LCH involves 2 or more organs and has a worse prognosis if risk organs (eg, liver, spleen, bone marrow) are involved.⁴

Skin lesions are reported in more than half of LCH cases and are the most common initial manifestation in patients younger than 2 years.⁴ Cutaneous findings are highly variable, which poses a diagnostic challenge. Common morphologies include erythematous papules, pustules, papulovesicles, scaly plaques, erosions, and petechiae. Lesions can be solitary or widespread and favor the trunk, head, and face.⁴ We describe an atypical case of hypopigmented cutaneous LCH and review the literature on this morphology in patients with skin of color.

A 7-month-old Hispanic male infant who was otherwise healthy presented with numerous hypopigmented macules and pink papules on the trunk and groin that had progressed since birth. A review of systems was unremarkable. Physical examination revealed 1- to 3-mm, discrete, hypopigmented macules intermixed with 1- to 2-mm pearly pink papules scattered on the back, chest, abdomen, and inguinal folds (Figure 1). Some lesions appeared koebnerized; however, the parents denied a history of scratching or trauma.

Histopathology of a lesion in the inguinal fold showed aggregates of mononuclear cells with reniform nuclei and abundant amphophilic cytoplasm in the papillary dermis, with focal extension into the epidermis. Scattered eosinophils and multinucleated giant cells were present in the dermal inflammatory infiltrate (Figure 2). Immunohistochemical staining was positive for CD1a (Figure 3) and S-100 protein (Figure 4). Although epidermal Langerhans cell collections also can be seen in allergic contact dermatitis,⁵ predominant involvement of the papillary dermis and the presence of multinucleated giant cells are characteristic of LCH.⁴ Given these findings, which were consistent with LCH, the dermatopathology deemed BRAF V600E immunostaining unnecessary for diagnostic purposes.

spudrichacrukap

slecospathocunaprubritrilulapriwrecuwonuclukogihadrinarobuwrofrophehisteprethituniclodichadetrimipiprocludeuastethipesteswochestophucricrumasigospiphadreshovucrinu

biclarehiprosticinalifroslestostapretuda

luludalecupacrimes

thekonaphechaswamuclawiproswochospostibrufrihuwrocloworunufradrakidospefraphiuechehoprithojuslowewrucothiphatrewr

The patient was referred to the hematology and oncology department to undergo thorough evaluation for extracutaneous involvement. The workup included a complete blood cell count, liver function testing, electrolyte assessment, skeletal survey, chest radiography, and ultrasonography of the liver and spleen. All results were negative, suggesting a diagnosis of single-system cutaneous LCH.

Three months later, the patient presented to dermatology with spontaneous regression of all skin lesions. Continued follow-up—every 6 months for 5 years—was recommended to monitor for disease recurrence or progression to multisystem disease.

Cutaneous LCH is a clinically heterogeneous disease with the potential for multisystem involvement and long-term sequelae; therefore, timely diagnosis is paramount to optimize outcomes. However, delayed diagnosis is common because of the spectrum of skin findings that can mimic common pediatric dermatoses, such as seborrheic dermatitis, atopic dermatitis, and diaper dermatitis.⁴ In one study, the median time from onset of skin lesions to diagnostic biopsy was longer than 3 months (maximum, 5 years).⁶ Our patient was referred to dermatology 7 months after onset of hypopigmented macules, a rarely reported cutaneous manifestation of LCH.

A PubMed search of articles indexed for MEDLINE from 1994 to 2019 using the terms Langerhans cell histiocytotis and hypopigmented yielded 17 cases of LCH presenting as hypopigmented skin lesions (Table).^7-22 All cases occurred in patients with skin of color (ie, patients of Asian, Hispanic, or African descent). Hypopigmented macules were the only cutaneous manifestation in 10 (59%) cases. Lesions most commonly were distributed on the trunk (16/17 [94%]) and extremities (8/17 [47%]). The median age of onset was 1 month; 76% (13/17) of patients developed skin lesions before 1 year of age, indicating that this morphology may be more common in newborns. In most patients, the diagnosis was single-system cutaneous LCH; they exhibited spontaneous regression by 8 months of age on average, suggesting that this variant may be associated with a better prognosis. Mori and colleagues²¹ hypothesized that hypopigmented lesions may represent the resolving stage of active LCH based on histopathologic findings of dermal pallor and fibrosis in a hypopigmented LCH lesion. However, systemic involvement was reported in 7 cases of hypopigmented LCH, highlighting the importance of assessing for multisystem disease regardless of cutaneous morphology.²¹Langerhans cell histiocytosis should be considered in the differential diagnosis when evaluating hypopigmented skin eruptions in infants with darker skin types. Prompt diagnosis of this atypical variant requires a higher index of suspicion because of its rarity and the polymorphic nature of cutaneous LCH. This morphology may go undiagnosed in the setting of mild or spontaneously resolving disease; notwithstanding, accurate diagnosis and longitudinal surveillance are necessary given the potential for progressive systemic involvement.

The risk for developing skin cancer can be somewhat attributed to variations in skin pigmentation. Historically, lighter skin pigmentation has been observed in populations living in higher latitudes and darker pigmentation in populations near the equator. Although skin pigmentation is a conglomeration of genetic and environmental factors, anthropologic studies have demonstrated an association of human skin lightening with historic human migratory patterns.¹ It is postulated that migration to latitudes with less UVB light penetration has resulted in a compensatory natural selection of lighter skin types. Furthermore, the driving force behind this migration-associated skin lightening has remained unclear.¹

The need for folate metabolism, vitamin D synthesis, and barrier protection, as well as cultural practices, has been postulated as driving factors for skin pigmentation variation. Synthesis of vitamin D is a UV radiation (UVR)–dependent process and has remained a prominent theoretical driver for the basis of evolutionary skin lightening. Vitamin D can be acquired both exogenously or endogenously via dietary supplementation or sunlight; however, historically it has been obtained through UVB exposure primarily. Once UVB is absorbed by the skin, it catalyzes conversion of 7-dehydrocholesterol to previtamin D₃, which is converted to vitamin D in the kidneys.^2,3 It is suggested that lighter skin tones have an advantage over darker skin tones in synthesizing vitamin D at higher latitudes where there is less UVB, thus leading to the adaptation process.1 In this systematic review, we analyzed the evolutionary vitamin D adaptation hypothesis and assessed the validity of evidence supporting this theory in the literature.

Methods

A search of PubMed, Embase, and the Cochrane Reviews database was conducted using the terms evolution, vitamin D, and skin to generate articles published from 2010 to 2022 that evaluated the influence of UVR-dependent production of vitamin D on skin pigmentation through historical migration patterns (Figure). Studies were excluded during an initial screening of abstracts followed by full-text assessment if they only had abstracts and if articles were inaccessible for review or in the form of case reports and commentaries.

The following data were extracted from each included study: reference citation, affiliated institutions of authors, author specialties, journal name, year of publication, study period, type of article, type of study, mechanism of adaptation, data concluding or supporting vitamin D as the driver, and data concluding or suggesting against vitamin D as the driver. Data concluding or supporting vitamin D as the driver were recorded from statistically significant results, study conclusions, and direct quotations. Data concluding or suggesting against vitamin D as the driver also were recorded from significant results, study conclusions, and direct quotes. The mechanism of adaptation was based on vitamin D synthesis modulation, melanin upregulation, genetic selections, genetic drift, mating patterns, increased vitamin D sensitivity, interbreeding, and diet.

Studies included in the analysis were placed into 1 of 3 categories: supporting, neutral, and against. Strength of Recommendation Taxonomy (SORT) criteria were used to classify the level of evidence of each article.⁴ Each article’s level of evidence was then graded (Table 1). The SORT grading levels were based on quality and evidence type: level 1 signified good-quality, patient-oriented evidence; level 2 signified limited-quality, patient-oriented evidence; and level 3 signified other evidence.⁴

Results

Article Selection—A total of 229 articles were identified for screening, and 39 studies met inclusion criteria.^1-3,5-40 Systematic and retrospective reviews were the most common types of studies. Genomic analysis/sequencing/genome-wide association studies (GWAS) were the most common methods of analysis. Of these 39 articles, 26 were classified as supporting the evolutionary vitamin D adaptation hypothesis, 10 were classified as neutral, and 3 were classified as against (Table 1). 

Of the articles classified as supporting the vitamin D hypothesis, 13 articles were level 1 evidence, 9 were level 2, and 4 were level 3. Key findings supporting the vitamin D hypothesis included genetic natural selection favoring vitamin D synthesis genes at higher latitudes with lower UVR and the skin lightening that occurred to protect against vitamin D deficiency (Table 1). Specific genes supporting these findings included 7-dehydrocholesterol reductase (DHCR7), vitamin D receptor (VDR), tyrosinase (TYR), tyrosinase-related protein 1 (TYRP1), oculocutaneous albinism type 2 melanosomal transmembrane protein (OCA2), solute carrier family 45 member 2 (SLC45A2), solute carrier family 4 member 5 (SLC24A5), Kit ligand (KITLG), melanocortin 1 receptor (MC1R), and HECT and RLD domain containing E3 ubiquitin protein ligase 2 (HERC2)(Table 2).

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Comment

The importance of appropriate vitamin D levels is hypothesized as a potent driver in skin lightening because the vitamin is essential for many biochemical processes within the human body. Proper calcification of bones requires activated vitamin D to prevent rickets in childhood. Pelvic deformation in women with rickets can obstruct childbirth in primitive medical environments.¹⁵ This direct reproductive impairment suggests a strong selective pressure for skin lightening in populations that migrated northward to enhance vitamin D synthesis. 

Of the 39 articles that we reviewed, the majority (n=26 [66.7%]) supported the hypothesis that vitamin D synthesis was the main driver behind skin lightening, whereas 3 (7.7%) did not support the hypothesis and 10 (25.6%) were neutral. Other leading theories explaining skin lightening included the idea that enhanced melanogenesis protected against folate degradation; genetic selection for light-skin alleles due to genetic drift; skin lightening being the result of sexual selection; and a combination of factors, including dietary choices, clothing preferences, and skin permeability barriers. 

Articles With Supporting Evidence for the Vitamin D Theory—As Homo sapiens migrated out of Africa, migration patterns demonstrated the correlation between distance from the equator and skin pigmentation from natural selection. Individuals with darker skin pigment required higher levels of UVR to synthesize vitamin D. According to Beleza et al,1 as humans migrated to areas of higher latitudes with lower levels of UVR, natural selection favored the development of lighter skin to maximize vitamin D production. Vitamin D is linked to calcium metabolism, and its deficiency can lead to bone malformations and poor immune function.³⁵ Several genes affecting melanogenesis and skin pigment have been found to have geospatial patterns that map to different geographic locations of various populations, indicating how human migration patterns out of Africa created this natural selection for skin lightening. The gene KITLG—associated with lighter skin pigmentation—has been found in high frequencies in both European and East Asian populations and is proposed to have increased in frequency after the migration out of Africa. However, the genes TYRP1, SLC24A5, and SLC45A2 were found at high frequencies only in European populations, and this selection occurred 11,000 to 19,000 years ago during the Last Glacial Maximum (15,000–20,000 years ago), demonstrating the selection for European over East Asian characteristics. During this period, seasonal changes increased the risk for vitamin D deficiency and provided an urgency for selection to a lighter skin pigment.¹

The migration of H sapiens to northern latitudes prompted the selection of alleles that would increasevitamin D synthesis to counteract the reduced UV exposure. Genetic analysis studies have found key associations between genes encoding for the metabolism of vitamin D and pigmentation. Among this complex network are the essential downstream enzymes in the melanocortin receptor 1 pathway, including TYR and TYRP1. Forty-six of 960 single-nucleotide polymorphisms located in 29 different genes involved in skin pigmentation that were analyzed in a cohort of 2970 individuals were significantly associated with serum vitamin D levels (P<.05). The exocyst complex component 2 (EXOC2), TYR, and TYRP1 gene variants were shown to have the greatest influence on vitamin D status.⁹ These data reveal how pigment genotypes are predictive of vitamin D levels and the epistatic potential among many genes in this complex network. 

Gene variation plays an important role in vitamin D status when comparing genetic polymorphisms in populations in northern latitudes to African populations. Vitamin D₃ precursor availability is decreased by 7-DHCR catalyzing the precursors substrate to cholesterol. In a study using GWAS, it was found that “variations in DHCR7 may aid vitamin D production by conserving cutaneous 7-DHC levels. A high prevalence of DHCR7 variants were found in European and Northeast Asian populations but not in African populations, suggesting that selection occurred for these DHCR7 mutations in populations who migrated to more northern latitudes.⁵ Multilocus networks have been established between the VDR promotor and skin color genes (Table 2) that exhibit a strong in-Africa vs out-of-Africa frequency pattern. It also has been shown that genetic variation (suggesting a long-term evolutionary inclination) and epigenetic modification (indicative of short-term exposure) of VDR lends support to the vitamin D hypothesis. As latitude decreases, prevalence of VDR FokI (F allele), BsmI (B allele), ApaI (A allele), and TaqI (T allele) also decreases in a linear manner, linking latitude to VDR polymorphisms. Plasma vitamin D levels and photoperiod of conception—UV exposure during the periconceptional period—also were extrapolative of VDR methylation in a study involving 80 participants, where these 2 factors accounted for 17% of variance in methylation.⁶

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wrehoswojospiswodenabrudephedorimuhedaciuihu

Other noteworthy genes included HERC2, which has implications in the expression of OCA2 (melanocyte-specific transporter protein), and IRF4, which encodes for an important enzyme in folate-dependent melanin production. In an Australian cross-sectional study that analyzed vitamin D and pigmentation gene polymorphisms in conjunction with plasma vitamin D levels, the most notable rate of vitamin D loss occurred in individuals with the darkest pigmentation HERC2 (AA) genotype.³¹ In contrast, the lightest pigmentation HERC2 (GG) genotypes had increased vitamin D₃ photosynthesis. Interestingly, the lightest interferon regulatory factor 4 (IRF4) TT genotype and the darkest HERC2 AA genotype, rendering the greatest folate loss and largest synthesis of vitamin D₃, were not seen in combination in any of the participants.³⁰ In addition to HERC2, derived alleles from pigment-associated genes SLC24A5*A and SLC45A2*G demonstrated greater frequencies in Europeans (>90%) compared to Africans and East Asians, where the allelic frequencies were either rare or absent.1 This evidence delineates not only the complexity but also the strong relationship between skin pigmentation, latitude, and vitamin D status. The GWAS also have supported this concept. In comparing European populations to African populations, there was a 4-fold increase in the frequencies of “derived alleles of the vitamin D transport protein (GC, rs3755967), the 25(OH)D₃ synthesizing enzyme (CYP2R1, rs10741657), VDR (rs2228570 (commonly known as FokI polymorphism), rs1544410 (Bsm1), and rs731236 (Taq1) and the VDR target genes CYP24A1 (rs17216707), CD14 (rs2569190), and CARD9 (rs4077515).”³²

Articles With Evidence Against the Vitamin D Theory—This review analyzed the level of support for the theory that vitamin D was the main driver for skin lightening. Although most articles supported this theory, there were articles that listed other plausible counterarguments. Jablonski and Chaplin3 suggested that humans living in higher latitudes compensated for increased demand of vitamin D by placing cultural importance on a diet of vitamin D–rich foods and thus would not have experienced decreased vitamin D levels, which we hypothesize were the driver for skin lightening. Elias et al³⁹ argued that initial pigment dilution may have instead served to improve metabolic conservation, as the authors found no evidence of rickets—the sequelae of vitamin D deficiency—in pre–industrial age human fossils. Elias and Williams3⁸ proposed that differences in skin pigment are due to a more intact skin permeability barrier as “a requirement for life in a desiccating terrestrial environment,” which is seen in darker skin tones compared to lighter skin tones and thus can survive better in warmer climates with less risk of infections or dehydration.

Articles With Neutral Evidence for the Vitamin D Theory—Greaves⁴¹ argued against the idea that skin evolved to become lighter to protect against vitamin D deficiency. They proposed that the chimpanzee, which is the human’s most closely related species, had light skin covered by hair, and the loss of this hair led to exposed pale skin that created a need for increased melanin production for protection from UVR. Greaves⁴¹ stated that the MC1R gene (associated with darker pigmentation) was selected for in African populations, and those with pale skin retained their original pigment as they migrated to higher latitudes. Further research has demonstrated that the genetic natural selection for skin pigment is a complex process that involves multiple gene variants found throughout cultures across the globe.

sobrochugiphipro

Conclusion

Skin pigmentation has continuously evolved alongside humans. Genetic selection for lighter skin coincides with a favorable selection for genes involved in vitamin D synthesis as humans migrated to northern latitudes, which enabled humans to produce adequate levels of exogenous vitamin D in low-UVR areas and in turn promoted survival. Early humans without access to supplementation or foods rich in vitamin D acquired vitamin D primarily through sunlight. In comparison to modern society, where vitamin D supplementation is accessible and human lifespans are prolonged, lighter skin tone is now a risk factor for malignant cancers of the skin rather than being a protective adaptation. Current sun behavior recommendations conclude that the body’s need for vitamin D is satisfied by UV exposure to the arms, legs, hands, and/or face for only 5 to 30 minutes between 10 am and 4 pm daily without sunscreen.^42-44 Approximately 600 IU of vitamin D supplementation daily is recommended in a typical adult younger than 70 years to avoid deficiency. In adults 70 years and older who are not receiving adequate sunlight exposure, 800 IU of daily vitamin D supplementation is recommended.⁴⁵

The hypothesis that skin lightening primarily was driven by the need for vitamin D can only be partially supported by our review. Studies have shown that there is a corresponding complex network of genes that determines skin pigmentation as well as vitamin D synthesis and conservation. However, there is sufficient evidence that skin lightening is multifactorial in nature, and vitamin D alone may not be the sole driver. The information in this review can be used by health care providers to educate patients on sun protection, given the lesser threat of severe vitamin D deficiency in developed communities today that have access to adequate nutrition and supplementation.

Skin lightening and its coinciding evolutionary drivers are a rather neglected area of research. Due to heterogeneous cohorts and conservative data analysis, GWAS studies run the risk of type II error, yielding a limitation in our data analysis.⁹ Furthermore, the data regarding specific time frames in evolutionary skin lightening as well as the intensity of gene polymorphisms are limited.1 Further studies are needed to determine the interconnectedness of the current skin-lightening theories to identify other important factors that may play a role in the process. Determining the key event can help us better understand skin-adaptation mechanisms and create a framework for understanding the vital process involved in adaptation, survival, and disease manifestation in different patient populations.

The risk for developing skin cancer can be somewhat attributed to variations in skin pigmentation. Historically, lighter skin pigmentation has been observed in populations living in higher latitudes and darker pigmentation in populations near the equator. Although skin pigmentation is a conglomeration of genetic and environmental factors, anthropologic studies have demonstrated an association of human skin lightening with historic human migratory patterns.¹ It is postulated that migration to latitudes with less UVB light penetration has resulted in a compensatory natural selection of lighter skin types. Furthermore, the driving force behind this migration-associated skin lightening has remained unclear.¹

The need for folate metabolism, vitamin D synthesis, and barrier protection, as well as cultural practices, has been postulated as driving factors for skin pigmentation variation. Synthesis of vitamin D is a UV radiation (UVR)–dependent process and has remained a prominent theoretical driver for the basis of evolutionary skin lightening. Vitamin D can be acquired both exogenously or endogenously via dietary supplementation or sunlight; however, historically it has been obtained through UVB exposure primarily. Once UVB is absorbed by the skin, it catalyzes conversion of 7-dehydrocholesterol to previtamin D₃, which is converted to vitamin D in the kidneys.^2,3 It is suggested that lighter skin tones have an advantage over darker skin tones in synthesizing vitamin D at higher latitudes where there is less UVB, thus leading to the adaptation process.1 In this systematic review, we analyzed the evolutionary vitamin D adaptation hypothesis and assessed the validity of evidence supporting this theory in the literature.

Methods

A search of PubMed, Embase, and the Cochrane Reviews database was conducted using the terms evolution, vitamin D, and skin to generate articles published from 2010 to 2022 that evaluated the influence of UVR-dependent production of vitamin D on skin pigmentation through historical migration patterns (Figure). Studies were excluded during an initial screening of abstracts followed by full-text assessment if they only had abstracts and if articles were inaccessible for review or in the form of case reports and commentaries.

The following data were extracted from each included study: reference citation, affiliated institutions of authors, author specialties, journal name, year of publication, study period, type of article, type of study, mechanism of adaptation, data concluding or supporting vitamin D as the driver, and data concluding or suggesting against vitamin D as the driver. Data concluding or supporting vitamin D as the driver were recorded from statistically significant results, study conclusions, and direct quotations. Data concluding or suggesting against vitamin D as the driver also were recorded from significant results, study conclusions, and direct quotes. The mechanism of adaptation was based on vitamin D synthesis modulation, melanin upregulation, genetic selections, genetic drift, mating patterns, increased vitamin D sensitivity, interbreeding, and diet.

Studies included in the analysis were placed into 1 of 3 categories: supporting, neutral, and against. Strength of Recommendation Taxonomy (SORT) criteria were used to classify the level of evidence of each article.⁴ Each article’s level of evidence was then graded (Table 1). The SORT grading levels were based on quality and evidence type: level 1 signified good-quality, patient-oriented evidence; level 2 signified limited-quality, patient-oriented evidence; and level 3 signified other evidence.⁴

Results

Article Selection—A total of 229 articles were identified for screening, and 39 studies met inclusion criteria.^1-3,5-40 Systematic and retrospective reviews were the most common types of studies. Genomic analysis/sequencing/genome-wide association studies (GWAS) were the most common methods of analysis. Of these 39 articles, 26 were classified as supporting the evolutionary vitamin D adaptation hypothesis, 10 were classified as neutral, and 3 were classified as against (Table 1). 

Of the articles classified as supporting the vitamin D hypothesis, 13 articles were level 1 evidence, 9 were level 2, and 4 were level 3. Key findings supporting the vitamin D hypothesis included genetic natural selection favoring vitamin D synthesis genes at higher latitudes with lower UVR and the skin lightening that occurred to protect against vitamin D deficiency (Table 1). Specific genes supporting these findings included 7-dehydrocholesterol reductase (DHCR7), vitamin D receptor (VDR), tyrosinase (TYR), tyrosinase-related protein 1 (TYRP1), oculocutaneous albinism type 2 melanosomal transmembrane protein (OCA2), solute carrier family 45 member 2 (SLC45A2), solute carrier family 4 member 5 (SLC24A5), Kit ligand (KITLG), melanocortin 1 receptor (MC1R), and HECT and RLD domain containing E3 ubiquitin protein ligase 2 (HERC2)(Table 2).

uolaslecluveclojibratigudrojimashedespehafrefregicubrivedesofrispeswajoswavatrulostikuspabroshiboswonewrusharuwrusokustetuchauokuuepavawrowrephikakideswijugidrupijechawatorophufruvecegonibroraprubestidramusp

Comment

The importance of appropriate vitamin D levels is hypothesized as a potent driver in skin lightening because the vitamin is essential for many biochemical processes within the human body. Proper calcification of bones requires activated vitamin D to prevent rickets in childhood. Pelvic deformation in women with rickets can obstruct childbirth in primitive medical environments.¹⁵ This direct reproductive impairment suggests a strong selective pressure for skin lightening in populations that migrated northward to enhance vitamin D synthesis. 

Of the 39 articles that we reviewed, the majority (n=26 [66.7%]) supported the hypothesis that vitamin D synthesis was the main driver behind skin lightening, whereas 3 (7.7%) did not support the hypothesis and 10 (25.6%) were neutral. Other leading theories explaining skin lightening included the idea that enhanced melanogenesis protected against folate degradation; genetic selection for light-skin alleles due to genetic drift; skin lightening being the result of sexual selection; and a combination of factors, including dietary choices, clothing preferences, and skin permeability barriers. 

Articles With Supporting Evidence for the Vitamin D Theory—As Homo sapiens migrated out of Africa, migration patterns demonstrated the correlation between distance from the equator and skin pigmentation from natural selection. Individuals with darker skin pigment required higher levels of UVR to synthesize vitamin D. According to Beleza et al,1 as humans migrated to areas of higher latitudes with lower levels of UVR, natural selection favored the development of lighter skin to maximize vitamin D production. Vitamin D is linked to calcium metabolism, and its deficiency can lead to bone malformations and poor immune function.³⁵ Several genes affecting melanogenesis and skin pigment have been found to have geospatial patterns that map to different geographic locations of various populations, indicating how human migration patterns out of Africa created this natural selection for skin lightening. The gene KITLG—associated with lighter skin pigmentation—has been found in high frequencies in both European and East Asian populations and is proposed to have increased in frequency after the migration out of Africa. However, the genes TYRP1, SLC24A5, and SLC45A2 were found at high frequencies only in European populations, and this selection occurred 11,000 to 19,000 years ago during the Last Glacial Maximum (15,000–20,000 years ago), demonstrating the selection for European over East Asian characteristics. During this period, seasonal changes increased the risk for vitamin D deficiency and provided an urgency for selection to a lighter skin pigment.¹

The migration of H sapiens to northern latitudes prompted the selection of alleles that would increasevitamin D synthesis to counteract the reduced UV exposure. Genetic analysis studies have found key associations between genes encoding for the metabolism of vitamin D and pigmentation. Among this complex network are the essential downstream enzymes in the melanocortin receptor 1 pathway, including TYR and TYRP1. Forty-six of 960 single-nucleotide polymorphisms located in 29 different genes involved in skin pigmentation that were analyzed in a cohort of 2970 individuals were significantly associated with serum vitamin D levels (P<.05). The exocyst complex component 2 (EXOC2), TYR, and TYRP1 gene variants were shown to have the greatest influence on vitamin D status.⁹ These data reveal how pigment genotypes are predictive of vitamin D levels and the epistatic potential among many genes in this complex network. 

Gene variation plays an important role in vitamin D status when comparing genetic polymorphisms in populations in northern latitudes to African populations. Vitamin D₃ precursor availability is decreased by 7-DHCR catalyzing the precursors substrate to cholesterol. In a study using GWAS, it was found that “variations in DHCR7 may aid vitamin D production by conserving cutaneous 7-DHC levels. A high prevalence of DHCR7 variants were found in European and Northeast Asian populations but not in African populations, suggesting that selection occurred for these DHCR7 mutations in populations who migrated to more northern latitudes.⁵ Multilocus networks have been established between the VDR promotor and skin color genes (Table 2) that exhibit a strong in-Africa vs out-of-Africa frequency pattern. It also has been shown that genetic variation (suggesting a long-term evolutionary inclination) and epigenetic modification (indicative of short-term exposure) of VDR lends support to the vitamin D hypothesis. As latitude decreases, prevalence of VDR FokI (F allele), BsmI (B allele), ApaI (A allele), and TaqI (T allele) also decreases in a linear manner, linking latitude to VDR polymorphisms. Plasma vitamin D levels and photoperiod of conception—UV exposure during the periconceptional period—also were extrapolative of VDR methylation in a study involving 80 participants, where these 2 factors accounted for 17% of variance in methylation.⁶

vephachiprobetrelisutruspishouishophipiphucluchegobesodroswodrasluchachukoprotecishustephocherotropruhiphigechacauojobrephufraswawracheslewechiwrispuspebelidrephegabrithuphoruphathaceboliw

wrehoswojospiswodenabrudephedorimuhedaciuihu

Other noteworthy genes included HERC2, which has implications in the expression of OCA2 (melanocyte-specific transporter protein), and IRF4, which encodes for an important enzyme in folate-dependent melanin production. In an Australian cross-sectional study that analyzed vitamin D and pigmentation gene polymorphisms in conjunction with plasma vitamin D levels, the most notable rate of vitamin D loss occurred in individuals with the darkest pigmentation HERC2 (AA) genotype.³¹ In contrast, the lightest pigmentation HERC2 (GG) genotypes had increased vitamin D₃ photosynthesis. Interestingly, the lightest interferon regulatory factor 4 (IRF4) TT genotype and the darkest HERC2 AA genotype, rendering the greatest folate loss and largest synthesis of vitamin D₃, were not seen in combination in any of the participants.³⁰ In addition to HERC2, derived alleles from pigment-associated genes SLC24A5*A and SLC45A2*G demonstrated greater frequencies in Europeans (>90%) compared to Africans and East Asians, where the allelic frequencies were either rare or absent.1 This evidence delineates not only the complexity but also the strong relationship between skin pigmentation, latitude, and vitamin D status. The GWAS also have supported this concept. In comparing European populations to African populations, there was a 4-fold increase in the frequencies of “derived alleles of the vitamin D transport protein (GC, rs3755967), the 25(OH)D₃ synthesizing enzyme (CYP2R1, rs10741657), VDR (rs2228570 (commonly known as FokI polymorphism), rs1544410 (Bsm1), and rs731236 (Taq1) and the VDR target genes CYP24A1 (rs17216707), CD14 (rs2569190), and CARD9 (rs4077515).”³²

Articles With Evidence Against the Vitamin D Theory—This review analyzed the level of support for the theory that vitamin D was the main driver for skin lightening. Although most articles supported this theory, there were articles that listed other plausible counterarguments. Jablonski and Chaplin3 suggested that humans living in higher latitudes compensated for increased demand of vitamin D by placing cultural importance on a diet of vitamin D–rich foods and thus would not have experienced decreased vitamin D levels, which we hypothesize were the driver for skin lightening. Elias et al³⁹ argued that initial pigment dilution may have instead served to improve metabolic conservation, as the authors found no evidence of rickets—the sequelae of vitamin D deficiency—in pre–industrial age human fossils. Elias and Williams3⁸ proposed that differences in skin pigment are due to a more intact skin permeability barrier as “a requirement for life in a desiccating terrestrial environment,” which is seen in darker skin tones compared to lighter skin tones and thus can survive better in warmer climates with less risk of infections or dehydration.

Articles With Neutral Evidence for the Vitamin D Theory—Greaves⁴¹ argued against the idea that skin evolved to become lighter to protect against vitamin D deficiency. They proposed that the chimpanzee, which is the human’s most closely related species, had light skin covered by hair, and the loss of this hair led to exposed pale skin that created a need for increased melanin production for protection from UVR. Greaves⁴¹ stated that the MC1R gene (associated with darker pigmentation) was selected for in African populations, and those with pale skin retained their original pigment as they migrated to higher latitudes. Further research has demonstrated that the genetic natural selection for skin pigment is a complex process that involves multiple gene variants found throughout cultures across the globe.

sobrochugiphipro

Conclusion

Skin pigmentation has continuously evolved alongside humans. Genetic selection for lighter skin coincides with a favorable selection for genes involved in vitamin D synthesis as humans migrated to northern latitudes, which enabled humans to produce adequate levels of exogenous vitamin D in low-UVR areas and in turn promoted survival. Early humans without access to supplementation or foods rich in vitamin D acquired vitamin D primarily through sunlight. In comparison to modern society, where vitamin D supplementation is accessible and human lifespans are prolonged, lighter skin tone is now a risk factor for malignant cancers of the skin rather than being a protective adaptation. Current sun behavior recommendations conclude that the body’s need for vitamin D is satisfied by UV exposure to the arms, legs, hands, and/or face for only 5 to 30 minutes between 10 am and 4 pm daily without sunscreen.^42-44 Approximately 600 IU of vitamin D supplementation daily is recommended in a typical adult younger than 70 years to avoid deficiency. In adults 70 years and older who are not receiving adequate sunlight exposure, 800 IU of daily vitamin D supplementation is recommended.⁴⁵

The hypothesis that skin lightening primarily was driven by the need for vitamin D can only be partially supported by our review. Studies have shown that there is a corresponding complex network of genes that determines skin pigmentation as well as vitamin D synthesis and conservation. However, there is sufficient evidence that skin lightening is multifactorial in nature, and vitamin D alone may not be the sole driver. The information in this review can be used by health care providers to educate patients on sun protection, given the lesser threat of severe vitamin D deficiency in developed communities today that have access to adequate nutrition and supplementation.

Skin lightening and its coinciding evolutionary drivers are a rather neglected area of research. Due to heterogeneous cohorts and conservative data analysis, GWAS studies run the risk of type II error, yielding a limitation in our data analysis.⁹ Furthermore, the data regarding specific time frames in evolutionary skin lightening as well as the intensity of gene polymorphisms are limited.1 Further studies are needed to determine the interconnectedness of the current skin-lightening theories to identify other important factors that may play a role in the process. Determining the key event can help us better understand skin-adaptation mechanisms and create a framework for understanding the vital process involved in adaptation, survival, and disease manifestation in different patient populations.

The risk for developing skin cancer can be somewhat attributed to variations in skin pigmentation. Historically, lighter skin pigmentation has been observed in populations living in higher latitudes and darker pigmentation in populations near the equator. Although skin pigmentation is a conglomeration of genetic and environmental factors, anthropologic studies have demonstrated an association of human skin lightening with historic human migratory patterns.¹ It is postulated that migration to latitudes with less UVB light penetration has resulted in a compensatory natural selection of lighter skin types. Furthermore, the driving force behind this migration-associated skin lightening has remained unclear.¹

The need for folate metabolism, vitamin D synthesis, and barrier protection, as well as cultural practices, has been postulated as driving factors for skin pigmentation variation. Synthesis of vitamin D is a UV radiation (UVR)–dependent process and has remained a prominent theoretical driver for the basis of evolutionary skin lightening. Vitamin D can be acquired both exogenously or endogenously via dietary supplementation or sunlight; however, historically it has been obtained through UVB exposure primarily. Once UVB is absorbed by the skin, it catalyzes conversion of 7-dehydrocholesterol to previtamin D₃, which is converted to vitamin D in the kidneys.^2,3 It is suggested that lighter skin tones have an advantage over darker skin tones in synthesizing vitamin D at higher latitudes where there is less UVB, thus leading to the adaptation process.1 In this systematic review, we analyzed the evolutionary vitamin D adaptation hypothesis and assessed the validity of evidence supporting this theory in the literature.

Methods

A search of PubMed, Embase, and the Cochrane Reviews database was conducted using the terms evolution, vitamin D, and skin to generate articles published from 2010 to 2022 that evaluated the influence of UVR-dependent production of vitamin D on skin pigmentation through historical migration patterns (Figure). Studies were excluded during an initial screening of abstracts followed by full-text assessment if they only had abstracts and if articles were inaccessible for review or in the form of case reports and commentaries.

The following data were extracted from each included study: reference citation, affiliated institutions of authors, author specialties, journal name, year of publication, study period, type of article, type of study, mechanism of adaptation, data concluding or supporting vitamin D as the driver, and data concluding or suggesting against vitamin D as the driver. Data concluding or supporting vitamin D as the driver were recorded from statistically significant results, study conclusions, and direct quotations. Data concluding or suggesting against vitamin D as the driver also were recorded from significant results, study conclusions, and direct quotes. The mechanism of adaptation was based on vitamin D synthesis modulation, melanin upregulation, genetic selections, genetic drift, mating patterns, increased vitamin D sensitivity, interbreeding, and diet.

Studies included in the analysis were placed into 1 of 3 categories: supporting, neutral, and against. Strength of Recommendation Taxonomy (SORT) criteria were used to classify the level of evidence of each article.⁴ Each article’s level of evidence was then graded (Table 1). The SORT grading levels were based on quality and evidence type: level 1 signified good-quality, patient-oriented evidence; level 2 signified limited-quality, patient-oriented evidence; and level 3 signified other evidence.⁴

Results

Article Selection—A total of 229 articles were identified for screening, and 39 studies met inclusion criteria.^1-3,5-40 Systematic and retrospective reviews were the most common types of studies. Genomic analysis/sequencing/genome-wide association studies (GWAS) were the most common methods of analysis. Of these 39 articles, 26 were classified as supporting the evolutionary vitamin D adaptation hypothesis, 10 were classified as neutral, and 3 were classified as against (Table 1). 

Of the articles classified as supporting the vitamin D hypothesis, 13 articles were level 1 evidence, 9 were level 2, and 4 were level 3. Key findings supporting the vitamin D hypothesis included genetic natural selection favoring vitamin D synthesis genes at higher latitudes with lower UVR and the skin lightening that occurred to protect against vitamin D deficiency (Table 1). Specific genes supporting these findings included 7-dehydrocholesterol reductase (DHCR7), vitamin D receptor (VDR), tyrosinase (TYR), tyrosinase-related protein 1 (TYRP1), oculocutaneous albinism type 2 melanosomal transmembrane protein (OCA2), solute carrier family 45 member 2 (SLC45A2), solute carrier family 4 member 5 (SLC24A5), Kit ligand (KITLG), melanocortin 1 receptor (MC1R), and HECT and RLD domain containing E3 ubiquitin protein ligase 2 (HERC2)(Table 2).

uolaslecluveclojibratigudrojimashedespehafrefregicubrivedesofrispeswajoswavatrulostikuspabroshiboswonewrusharuwrusokustetuchauokuuepavawrowrephikakideswijugidrupijechawatorophufruvecegonibroraprubestidramusp

Comment

The importance of appropriate vitamin D levels is hypothesized as a potent driver in skin lightening because the vitamin is essential for many biochemical processes within the human body. Proper calcification of bones requires activated vitamin D to prevent rickets in childhood. Pelvic deformation in women with rickets can obstruct childbirth in primitive medical environments.¹⁵ This direct reproductive impairment suggests a strong selective pressure for skin lightening in populations that migrated northward to enhance vitamin D synthesis. 

Of the 39 articles that we reviewed, the majority (n=26 [66.7%]) supported the hypothesis that vitamin D synthesis was the main driver behind skin lightening, whereas 3 (7.7%) did not support the hypothesis and 10 (25.6%) were neutral. Other leading theories explaining skin lightening included the idea that enhanced melanogenesis protected against folate degradation; genetic selection for light-skin alleles due to genetic drift; skin lightening being the result of sexual selection; and a combination of factors, including dietary choices, clothing preferences, and skin permeability barriers. 

Articles With Supporting Evidence for the Vitamin D Theory—As Homo sapiens migrated out of Africa, migration patterns demonstrated the correlation between distance from the equator and skin pigmentation from natural selection. Individuals with darker skin pigment required higher levels of UVR to synthesize vitamin D. According to Beleza et al,1 as humans migrated to areas of higher latitudes with lower levels of UVR, natural selection favored the development of lighter skin to maximize vitamin D production. Vitamin D is linked to calcium metabolism, and its deficiency can lead to bone malformations and poor immune function.³⁵ Several genes affecting melanogenesis and skin pigment have been found to have geospatial patterns that map to different geographic locations of various populations, indicating how human migration patterns out of Africa created this natural selection for skin lightening. The gene KITLG—associated with lighter skin pigmentation—has been found in high frequencies in both European and East Asian populations and is proposed to have increased in frequency after the migration out of Africa. However, the genes TYRP1, SLC24A5, and SLC45A2 were found at high frequencies only in European populations, and this selection occurred 11,000 to 19,000 years ago during the Last Glacial Maximum (15,000–20,000 years ago), demonstrating the selection for European over East Asian characteristics. During this period, seasonal changes increased the risk for vitamin D deficiency and provided an urgency for selection to a lighter skin pigment.¹

The migration of H sapiens to northern latitudes prompted the selection of alleles that would increasevitamin D synthesis to counteract the reduced UV exposure. Genetic analysis studies have found key associations between genes encoding for the metabolism of vitamin D and pigmentation. Among this complex network are the essential downstream enzymes in the melanocortin receptor 1 pathway, including TYR and TYRP1. Forty-six of 960 single-nucleotide polymorphisms located in 29 different genes involved in skin pigmentation that were analyzed in a cohort of 2970 individuals were significantly associated with serum vitamin D levels (P<.05). The exocyst complex component 2 (EXOC2), TYR, and TYRP1 gene variants were shown to have the greatest influence on vitamin D status.⁹ These data reveal how pigment genotypes are predictive of vitamin D levels and the epistatic potential among many genes in this complex network. 

Gene variation plays an important role in vitamin D status when comparing genetic polymorphisms in populations in northern latitudes to African populations. Vitamin D₃ precursor availability is decreased by 7-DHCR catalyzing the precursors substrate to cholesterol. In a study using GWAS, it was found that “variations in DHCR7 may aid vitamin D production by conserving cutaneous 7-DHC levels. A high prevalence of DHCR7 variants were found in European and Northeast Asian populations but not in African populations, suggesting that selection occurred for these DHCR7 mutations in populations who migrated to more northern latitudes.⁵ Multilocus networks have been established between the VDR promotor and skin color genes (Table 2) that exhibit a strong in-Africa vs out-of-Africa frequency pattern. It also has been shown that genetic variation (suggesting a long-term evolutionary inclination) and epigenetic modification (indicative of short-term exposure) of VDR lends support to the vitamin D hypothesis. As latitude decreases, prevalence of VDR FokI (F allele), BsmI (B allele), ApaI (A allele), and TaqI (T allele) also decreases in a linear manner, linking latitude to VDR polymorphisms. Plasma vitamin D levels and photoperiod of conception—UV exposure during the periconceptional period—also were extrapolative of VDR methylation in a study involving 80 participants, where these 2 factors accounted for 17% of variance in methylation.⁶

vephachiprobetrelisutruspishouishophipiphucluchegobesodroswodrasluchachukoprotecishustephocherotropruhiphigechacauojobrephufraswawracheslewechiwrispuspebelidrephegabrithuphoruphathaceboliw

wrehoswojospiswodenabrudephedorimuhedaciuihu

Other noteworthy genes included HERC2, which has implications in the expression of OCA2 (melanocyte-specific transporter protein), and IRF4, which encodes for an important enzyme in folate-dependent melanin production. In an Australian cross-sectional study that analyzed vitamin D and pigmentation gene polymorphisms in conjunction with plasma vitamin D levels, the most notable rate of vitamin D loss occurred in individuals with the darkest pigmentation HERC2 (AA) genotype.³¹ In contrast, the lightest pigmentation HERC2 (GG) genotypes had increased vitamin D₃ photosynthesis. Interestingly, the lightest interferon regulatory factor 4 (IRF4) TT genotype and the darkest HERC2 AA genotype, rendering the greatest folate loss and largest synthesis of vitamin D₃, were not seen in combination in any of the participants.³⁰ In addition to HERC2, derived alleles from pigment-associated genes SLC24A5*A and SLC45A2*G demonstrated greater frequencies in Europeans (>90%) compared to Africans and East Asians, where the allelic frequencies were either rare or absent.1 This evidence delineates not only the complexity but also the strong relationship between skin pigmentation, latitude, and vitamin D status. The GWAS also have supported this concept. In comparing European populations to African populations, there was a 4-fold increase in the frequencies of “derived alleles of the vitamin D transport protein (GC, rs3755967), the 25(OH)D₃ synthesizing enzyme (CYP2R1, rs10741657), VDR (rs2228570 (commonly known as FokI polymorphism), rs1544410 (Bsm1), and rs731236 (Taq1) and the VDR target genes CYP24A1 (rs17216707), CD14 (rs2569190), and CARD9 (rs4077515).”³²

Articles With Evidence Against the Vitamin D Theory—This review analyzed the level of support for the theory that vitamin D was the main driver for skin lightening. Although most articles supported this theory, there were articles that listed other plausible counterarguments. Jablonski and Chaplin3 suggested that humans living in higher latitudes compensated for increased demand of vitamin D by placing cultural importance on a diet of vitamin D–rich foods and thus would not have experienced decreased vitamin D levels, which we hypothesize were the driver for skin lightening. Elias et al³⁹ argued that initial pigment dilution may have instead served to improve metabolic conservation, as the authors found no evidence of rickets—the sequelae of vitamin D deficiency—in pre–industrial age human fossils. Elias and Williams3⁸ proposed that differences in skin pigment are due to a more intact skin permeability barrier as “a requirement for life in a desiccating terrestrial environment,” which is seen in darker skin tones compared to lighter skin tones and thus can survive better in warmer climates with less risk of infections or dehydration.

Articles With Neutral Evidence for the Vitamin D Theory—Greaves⁴¹ argued against the idea that skin evolved to become lighter to protect against vitamin D deficiency. They proposed that the chimpanzee, which is the human’s most closely related species, had light skin covered by hair, and the loss of this hair led to exposed pale skin that created a need for increased melanin production for protection from UVR. Greaves⁴¹ stated that the MC1R gene (associated with darker pigmentation) was selected for in African populations, and those with pale skin retained their original pigment as they migrated to higher latitudes. Further research has demonstrated that the genetic natural selection for skin pigment is a complex process that involves multiple gene variants found throughout cultures across the globe.

sobrochugiphipro

Conclusion

Skin pigmentation has continuously evolved alongside humans. Genetic selection for lighter skin coincides with a favorable selection for genes involved in vitamin D synthesis as humans migrated to northern latitudes, which enabled humans to produce adequate levels of exogenous vitamin D in low-UVR areas and in turn promoted survival. Early humans without access to supplementation or foods rich in vitamin D acquired vitamin D primarily through sunlight. In comparison to modern society, where vitamin D supplementation is accessible and human lifespans are prolonged, lighter skin tone is now a risk factor for malignant cancers of the skin rather than being a protective adaptation. Current sun behavior recommendations conclude that the body’s need for vitamin D is satisfied by UV exposure to the arms, legs, hands, and/or face for only 5 to 30 minutes between 10 am and 4 pm daily without sunscreen.^42-44 Approximately 600 IU of vitamin D supplementation daily is recommended in a typical adult younger than 70 years to avoid deficiency. In adults 70 years and older who are not receiving adequate sunlight exposure, 800 IU of daily vitamin D supplementation is recommended.⁴⁵

The hypothesis that skin lightening primarily was driven by the need for vitamin D can only be partially supported by our review. Studies have shown that there is a corresponding complex network of genes that determines skin pigmentation as well as vitamin D synthesis and conservation. However, there is sufficient evidence that skin lightening is multifactorial in nature, and vitamin D alone may not be the sole driver. The information in this review can be used by health care providers to educate patients on sun protection, given the lesser threat of severe vitamin D deficiency in developed communities today that have access to adequate nutrition and supplementation.

Skin lightening and its coinciding evolutionary drivers are a rather neglected area of research. Due to heterogeneous cohorts and conservative data analysis, GWAS studies run the risk of type II error, yielding a limitation in our data analysis.⁹ Furthermore, the data regarding specific time frames in evolutionary skin lightening as well as the intensity of gene polymorphisms are limited.1 Further studies are needed to determine the interconnectedness of the current skin-lightening theories to identify other important factors that may play a role in the process. Determining the key event can help us better understand skin-adaptation mechanisms and create a framework for understanding the vital process involved in adaptation, survival, and disease manifestation in different patient populations.

To the Editor:

A 42-year man presented with hollowing of the upper eyelid and skin discoloration of the left periorbital area of 10 years’ duration. He was a professional mixed martial arts fighter with a history of 2 surgeries for retinal detachment of the left eye 13 years prior to the current presentation. The patient also has macular scarring in the left eye. He denied a history of facial fracture, reconstructive surgery, or other medical conditions. His visual acuity was unknown; however, he did not require corrective glasses. He used 3 prescription ophthalmic eye drops—dorzolamide hydrochloride plus timolol maleate, 10 mL; brimonidine tartrate ophthalmic solution 0.15%, 5 mL; and latanoprost ophthalmic solution 0.005%, 125 μg/2.5 mL—in the left eye to lower intraocular pressure, as therapy for glaucoma. If left untreated, glaucoma can lead to vision loss.

Physical examination revealed periorbital hyperpigmentation on the left side; hypertrichosis and eyelash trichomegaly compared to the right side; and a deep left upper orbital sulcus compared to the right side (Figure). The patient was alert and oriented to person, place, and time. Extraocular movement was intact bilaterally, and his pupillary reflex was symmetric. No tenderness was noted over the affected area on palpation; no subcutaneous masses or lesions were observed or palpated. There was no ocular discharge, the conjunctiva was pink, and the sclera was white bilaterally.

CT113004025_fig.jpg

The differential diagnosis included professional trauma-induced orbital changes, nevus of Ota (oculomucodermal melanocytosis), prostaglandin-associated periorbitopathy (PAP), and melasma. Although the patient sustained an injury that caused retinal detachment, he never experienced an orbital bone fracture; additionally, a fracture would not explain the skin discoloration or longer eyelashes. Periorbital nevus of Ota most commonly manifests as a unilateral scleral and brown-bluish skin discoloration but does not cause hollowing of the orbital sulcus or affect the length and thickness of eyelashes. Melasma—bilateral skin hyperpigmentation that most commonly affects women—can be induced by oral contraceptives, antibiotics, heat, sun exposure, and pregnancy. It does not affect the color of the iris or the depth of the scleral sulcus, and it does not increase the length and thickness of eyelashes. Based on the clinical presentation and a review of the eye drops used, he was diagnosed with PAP due to prolonged use of latanoprost ophthalmic solution. The patient was referred to an ophthalmologist for consideration of a switch to a different class of medication.

Of the 3 eye drops used by this patient, latanoprost, a prostaglandin analog, decreases intraocular pressure and is known to cause PAP. This condition comprises a constellation of changes, including upper eyelid ptosis, deepening of the upper eyelid sulcus, involution of dermatochalasis, periorbital fat atrophy, mild enophthalmos (sunken eye), inferior scleral show, increased prominence of eyelid vessels, and tight eyelids.¹ Latanoprost most often produces these findings, but all prostaglandin ophthalmic medications can, including the dual-indication bimatoprost, which was approved by the US Food and Drug Administration to reduce elevated intraocular pressure in patients with open-angle glaucoma or ocular hypertension but also is used to grow darker, thicker, and longer eyelashes. Clinicians who prescribe bimatoprost for this cosmetic indication should be mindful of the potential for PAP and discuss it with patients.

The prescribing information (PI) for bimatoprost (Latisse; Allergan) does not list PAP as an adverse reaction observed in the 4-month multicenter, double-blind, randomized, vehicle-controlled study of bimatoprost (as Latisse) in 278 adults.² The PI does list “periorbital and lid changes associated with periorbital fat atrophy and skin tightness resulting in deepening of eyelid sulcus and eyelid ptosis” as an adverse reaction in postmarketing experience. However, according to the PI, the frequency of these adverse reactions cannot be established, as the reporting of such incidents was voluntary and the size of the treated population was uncertain.²

Prostaglandins can cause periorbitopathy by several mechanisms; one speculated cause is that this group of medications might provoke smooth muscle contraction. Prostaglandin medications also have an affinity for fat cells¹; atrophy of fat cells can lead to enophthalmos and deepening upper eyelid sulcus. In an observational study of 105 participants who were using a prostaglandin in 1 eye for longer than 1 month (the other eye was used as a control), the overall frequency of prostaglandin-associated periorbitopathy was 93.3% in the bimatoprost group, 41.4% in the latanoprost group, and 70% in the travoprost group, while the frequency of deepening of the upper eyelid sulcus was 80% in the bimatoprost group, 15.7% in the latanoprost group, and 45% in the travoprost group.³ These changes may not be as striking when a patient is using a prostaglandin ophthalmic medication in both eyes and may not be noticed even by the patient. It is prudent for the clinician to take a baseline photograph of the patient when these medications are prescribed to observe for early signs of periorbitopathy. These adverse effects may not be reversible when the medication is discontinued⁴ and have been observed as early as 4 to 6 weeks after the start of treatment.⁵

Our patient was counseled that his constellation of PAP findings potentially could be partially reversed over months or even a year or longer if the offending agent was discontinued. However, he was cautioned that cessation of latanoprost first needed to be discussed with his ophthalmologist, who would determine if there was a suitable alternative to a prostaglandin analog for him. The patient’s only concern was the aesthetic appearance of the left periorbital area. A hyaluronic acid filler or fat grafting can be considered for correction of orbital sulcus hollowing; however, we could not locate any long-term studies in which such corrective treatments were applied for PAP. Our patient continues to use latanoprost with no change in the frequency of use. There have been no further changes or progression in the physical appearance of the left eye or periorbital area. The patient has not undergone any corrective treatments.

To the Editor:

A 42-year man presented with hollowing of the upper eyelid and skin discoloration of the left periorbital area of 10 years’ duration. He was a professional mixed martial arts fighter with a history of 2 surgeries for retinal detachment of the left eye 13 years prior to the current presentation. The patient also has macular scarring in the left eye. He denied a history of facial fracture, reconstructive surgery, or other medical conditions. His visual acuity was unknown; however, he did not require corrective glasses. He used 3 prescription ophthalmic eye drops—dorzolamide hydrochloride plus timolol maleate, 10 mL; brimonidine tartrate ophthalmic solution 0.15%, 5 mL; and latanoprost ophthalmic solution 0.005%, 125 μg/2.5 mL—in the left eye to lower intraocular pressure, as therapy for glaucoma. If left untreated, glaucoma can lead to vision loss.

Physical examination revealed periorbital hyperpigmentation on the left side; hypertrichosis and eyelash trichomegaly compared to the right side; and a deep left upper orbital sulcus compared to the right side (Figure). The patient was alert and oriented to person, place, and time. Extraocular movement was intact bilaterally, and his pupillary reflex was symmetric. No tenderness was noted over the affected area on palpation; no subcutaneous masses or lesions were observed or palpated. There was no ocular discharge, the conjunctiva was pink, and the sclera was white bilaterally.

CT113004025_fig.jpg

The differential diagnosis included professional trauma-induced orbital changes, nevus of Ota (oculomucodermal melanocytosis), prostaglandin-associated periorbitopathy (PAP), and melasma. Although the patient sustained an injury that caused retinal detachment, he never experienced an orbital bone fracture; additionally, a fracture would not explain the skin discoloration or longer eyelashes. Periorbital nevus of Ota most commonly manifests as a unilateral scleral and brown-bluish skin discoloration but does not cause hollowing of the orbital sulcus or affect the length and thickness of eyelashes. Melasma—bilateral skin hyperpigmentation that most commonly affects women—can be induced by oral contraceptives, antibiotics, heat, sun exposure, and pregnancy. It does not affect the color of the iris or the depth of the scleral sulcus, and it does not increase the length and thickness of eyelashes. Based on the clinical presentation and a review of the eye drops used, he was diagnosed with PAP due to prolonged use of latanoprost ophthalmic solution. The patient was referred to an ophthalmologist for consideration of a switch to a different class of medication.

Of the 3 eye drops used by this patient, latanoprost, a prostaglandin analog, decreases intraocular pressure and is known to cause PAP. This condition comprises a constellation of changes, including upper eyelid ptosis, deepening of the upper eyelid sulcus, involution of dermatochalasis, periorbital fat atrophy, mild enophthalmos (sunken eye), inferior scleral show, increased prominence of eyelid vessels, and tight eyelids.¹ Latanoprost most often produces these findings, but all prostaglandin ophthalmic medications can, including the dual-indication bimatoprost, which was approved by the US Food and Drug Administration to reduce elevated intraocular pressure in patients with open-angle glaucoma or ocular hypertension but also is used to grow darker, thicker, and longer eyelashes. Clinicians who prescribe bimatoprost for this cosmetic indication should be mindful of the potential for PAP and discuss it with patients.

The prescribing information (PI) for bimatoprost (Latisse; Allergan) does not list PAP as an adverse reaction observed in the 4-month multicenter, double-blind, randomized, vehicle-controlled study of bimatoprost (as Latisse) in 278 adults.² The PI does list “periorbital and lid changes associated with periorbital fat atrophy and skin tightness resulting in deepening of eyelid sulcus and eyelid ptosis” as an adverse reaction in postmarketing experience. However, according to the PI, the frequency of these adverse reactions cannot be established, as the reporting of such incidents was voluntary and the size of the treated population was uncertain.²

Prostaglandins can cause periorbitopathy by several mechanisms; one speculated cause is that this group of medications might provoke smooth muscle contraction. Prostaglandin medications also have an affinity for fat cells¹; atrophy of fat cells can lead to enophthalmos and deepening upper eyelid sulcus. In an observational study of 105 participants who were using a prostaglandin in 1 eye for longer than 1 month (the other eye was used as a control), the overall frequency of prostaglandin-associated periorbitopathy was 93.3% in the bimatoprost group, 41.4% in the latanoprost group, and 70% in the travoprost group, while the frequency of deepening of the upper eyelid sulcus was 80% in the bimatoprost group, 15.7% in the latanoprost group, and 45% in the travoprost group.³ These changes may not be as striking when a patient is using a prostaglandin ophthalmic medication in both eyes and may not be noticed even by the patient. It is prudent for the clinician to take a baseline photograph of the patient when these medications are prescribed to observe for early signs of periorbitopathy. These adverse effects may not be reversible when the medication is discontinued⁴ and have been observed as early as 4 to 6 weeks after the start of treatment.⁵

Our patient was counseled that his constellation of PAP findings potentially could be partially reversed over months or even a year or longer if the offending agent was discontinued. However, he was cautioned that cessation of latanoprost first needed to be discussed with his ophthalmologist, who would determine if there was a suitable alternative to a prostaglandin analog for him. The patient’s only concern was the aesthetic appearance of the left periorbital area. A hyaluronic acid filler or fat grafting can be considered for correction of orbital sulcus hollowing; however, we could not locate any long-term studies in which such corrective treatments were applied for PAP. Our patient continues to use latanoprost with no change in the frequency of use. There have been no further changes or progression in the physical appearance of the left eye or periorbital area. The patient has not undergone any corrective treatments.

To the Editor:

A 42-year man presented with hollowing of the upper eyelid and skin discoloration of the left periorbital area of 10 years’ duration. He was a professional mixed martial arts fighter with a history of 2 surgeries for retinal detachment of the left eye 13 years prior to the current presentation. The patient also has macular scarring in the left eye. He denied a history of facial fracture, reconstructive surgery, or other medical conditions. His visual acuity was unknown; however, he did not require corrective glasses. He used 3 prescription ophthalmic eye drops—dorzolamide hydrochloride plus timolol maleate, 10 mL; brimonidine tartrate ophthalmic solution 0.15%, 5 mL; and latanoprost ophthalmic solution 0.005%, 125 μg/2.5 mL—in the left eye to lower intraocular pressure, as therapy for glaucoma. If left untreated, glaucoma can lead to vision loss.

Physical examination revealed periorbital hyperpigmentation on the left side; hypertrichosis and eyelash trichomegaly compared to the right side; and a deep left upper orbital sulcus compared to the right side (Figure). The patient was alert and oriented to person, place, and time. Extraocular movement was intact bilaterally, and his pupillary reflex was symmetric. No tenderness was noted over the affected area on palpation; no subcutaneous masses or lesions were observed or palpated. There was no ocular discharge, the conjunctiva was pink, and the sclera was white bilaterally.

CT113004025_fig.jpg

The differential diagnosis included professional trauma-induced orbital changes, nevus of Ota (oculomucodermal melanocytosis), prostaglandin-associated periorbitopathy (PAP), and melasma. Although the patient sustained an injury that caused retinal detachment, he never experienced an orbital bone fracture; additionally, a fracture would not explain the skin discoloration or longer eyelashes. Periorbital nevus of Ota most commonly manifests as a unilateral scleral and brown-bluish skin discoloration but does not cause hollowing of the orbital sulcus or affect the length and thickness of eyelashes. Melasma—bilateral skin hyperpigmentation that most commonly affects women—can be induced by oral contraceptives, antibiotics, heat, sun exposure, and pregnancy. It does not affect the color of the iris or the depth of the scleral sulcus, and it does not increase the length and thickness of eyelashes. Based on the clinical presentation and a review of the eye drops used, he was diagnosed with PAP due to prolonged use of latanoprost ophthalmic solution. The patient was referred to an ophthalmologist for consideration of a switch to a different class of medication.

Of the 3 eye drops used by this patient, latanoprost, a prostaglandin analog, decreases intraocular pressure and is known to cause PAP. This condition comprises a constellation of changes, including upper eyelid ptosis, deepening of the upper eyelid sulcus, involution of dermatochalasis, periorbital fat atrophy, mild enophthalmos (sunken eye), inferior scleral show, increased prominence of eyelid vessels, and tight eyelids.¹ Latanoprost most often produces these findings, but all prostaglandin ophthalmic medications can, including the dual-indication bimatoprost, which was approved by the US Food and Drug Administration to reduce elevated intraocular pressure in patients with open-angle glaucoma or ocular hypertension but also is used to grow darker, thicker, and longer eyelashes. Clinicians who prescribe bimatoprost for this cosmetic indication should be mindful of the potential for PAP and discuss it with patients.

The prescribing information (PI) for bimatoprost (Latisse; Allergan) does not list PAP as an adverse reaction observed in the 4-month multicenter, double-blind, randomized, vehicle-controlled study of bimatoprost (as Latisse) in 278 adults.² The PI does list “periorbital and lid changes associated with periorbital fat atrophy and skin tightness resulting in deepening of eyelid sulcus and eyelid ptosis” as an adverse reaction in postmarketing experience. However, according to the PI, the frequency of these adverse reactions cannot be established, as the reporting of such incidents was voluntary and the size of the treated population was uncertain.²

Prostaglandins can cause periorbitopathy by several mechanisms; one speculated cause is that this group of medications might provoke smooth muscle contraction. Prostaglandin medications also have an affinity for fat cells¹; atrophy of fat cells can lead to enophthalmos and deepening upper eyelid sulcus. In an observational study of 105 participants who were using a prostaglandin in 1 eye for longer than 1 month (the other eye was used as a control), the overall frequency of prostaglandin-associated periorbitopathy was 93.3% in the bimatoprost group, 41.4% in the latanoprost group, and 70% in the travoprost group, while the frequency of deepening of the upper eyelid sulcus was 80% in the bimatoprost group, 15.7% in the latanoprost group, and 45% in the travoprost group.³ These changes may not be as striking when a patient is using a prostaglandin ophthalmic medication in both eyes and may not be noticed even by the patient. It is prudent for the clinician to take a baseline photograph of the patient when these medications are prescribed to observe for early signs of periorbitopathy. These adverse effects may not be reversible when the medication is discontinued⁴ and have been observed as early as 4 to 6 weeks after the start of treatment.⁵

Our patient was counseled that his constellation of PAP findings potentially could be partially reversed over months or even a year or longer if the offending agent was discontinued. However, he was cautioned that cessation of latanoprost first needed to be discussed with his ophthalmologist, who would determine if there was a suitable alternative to a prostaglandin analog for him. The patient’s only concern was the aesthetic appearance of the left periorbital area. A hyaluronic acid filler or fat grafting can be considered for correction of orbital sulcus hollowing; however, we could not locate any long-term studies in which such corrective treatments were applied for PAP. Our patient continues to use latanoprost with no change in the frequency of use. There have been no further changes or progression in the physical appearance of the left eye or periorbital area. The patient has not undergone any corrective treatments.

To the Editor:

Vitiligo is a depigmentation disorder that results from the loss of melanocytes in the epidermis.¹ The most widely accepted pathophysiology for melanocyte destruction in vitiligo is an autoimmune process involving dysregulated cytokine production and autoreactive T-cell activation.¹ Individuals with cutaneous autoinflammatory conditions currently are vital patient populations warranting research, as their susceptibility to COVID-19 infection may differ from the general population. We previously found a small increased risk for COVID-19 infection in patients with psoriasis,² which suggests that other dermatologic conditions also may impact COVID-19 risk. The risk for COVID-19 infection in patients with vitiligo remains largely unknown. In this retrospective cohort study, we investigated the risk for COVID-19 infection in patients with vitiligo compared with those without vitiligo utilizing claims data from the COVID-19 Research Database (https://covid19researchdatabase.org/).

Claims were evaluated for patients aged 3 years and older with a vitiligo diagnosis (International Classification of Diseases, Tenth Revision [ICD-10] code L80) that was made between January 1, 2016, and January 1, 2020. Individuals without a vitiligo diagnosis during the same period were placed (4:1 ratio) in the control group and were matched with study group patients for age and sex. All comorbidity variables and vitiligo diagnoses were extracted from ICD-10 codes that were given prior to a diagnosis of COVID-19. We then constructed multivariable logistic regression models adjusting for measured confounders to evaluate if vitiligo was associated with higher risk for COVID-19 infection after January 1, 2020.

The vitiligo and nonvitiligo cohorts included 40,363 and 161,452 patients, respectively (Table 1). Logistic regression analysis with adjustment for confounding variables, including high comorbid risk factors (Table 2) revealed that patients with a diagnosis of vitiligo had significantly increased odds of COVID-19 infection compared with patients without vitiligo (adjusted odds ratio [AOR], 1.47; 95% CI, 1.37-1.57; P<.001)(Table 3). Additionally, subgroup logistic analyses for sex, age, and exclusion of patients who were HIV positive revealed that females with vitiligo had higher odds of contracting COVID-19 than males with vitiligo (Table 3).

CT113004030_Table1.jpg

Our results showed that patients with vitiligo had a higher relative risk for contracting COVID-19 than individuals without vitiligo. It has been reported that the prevalence of COVID-19 is higher among patients with autoimmune diseases compared to the general population.³ Additionally, a handful of vitiligo patients are managed with immunosuppressive agents that may further weaken their immune response.¹ Moreover, survey results from dermatologists managing vitiligo patients revealed that physicians were fairly comfortable prescribing immunosuppressants and encouraging in-office phototherapy during the COVID-19 pandemic.⁴ As a result, more patients may have been attending in-office visits for their phototherapy, which may have increased their risk for COVID-19. Although these factors play a role in ­COVID-19 infection rates, the underlying immune dysregulation in vitiligo in relation to COVID-19 remains unknown and should be further explored.

CT113004030_Table2.jpg

Our findings are limited by the use of ICD-10 codes, the inability to control for all potential confounding variables, the lack of data regarding the stage of vitiligo, and the absence of data for undiagnosed COVID-19 infections. In addition, patients with vitiligo may be more likely to seek care, potentially increasing their rates of COVID-19 testing. The inability to identify the stage of vitiligo during enrollment in the database may have altered our results, as individuals with active disease have increased levels of IFN-γ. Increased secretion of IFN-γ also potentially helps in the clearance of COVID-19 infection.¹ Future studies should investigate this relationship via planned ­COVID-19 testing, identification of vitiligo stage, and controlling for other associated comorbidities.

CT113004030_Table3.jpg

To the Editor:

Vitiligo is a depigmentation disorder that results from the loss of melanocytes in the epidermis.¹ The most widely accepted pathophysiology for melanocyte destruction in vitiligo is an autoimmune process involving dysregulated cytokine production and autoreactive T-cell activation.¹ Individuals with cutaneous autoinflammatory conditions currently are vital patient populations warranting research, as their susceptibility to COVID-19 infection may differ from the general population. We previously found a small increased risk for COVID-19 infection in patients with psoriasis,² which suggests that other dermatologic conditions also may impact COVID-19 risk. The risk for COVID-19 infection in patients with vitiligo remains largely unknown. In this retrospective cohort study, we investigated the risk for COVID-19 infection in patients with vitiligo compared with those without vitiligo utilizing claims data from the COVID-19 Research Database (https://covid19researchdatabase.org/).

Claims were evaluated for patients aged 3 years and older with a vitiligo diagnosis (International Classification of Diseases, Tenth Revision [ICD-10] code L80) that was made between January 1, 2016, and January 1, 2020. Individuals without a vitiligo diagnosis during the same period were placed (4:1 ratio) in the control group and were matched with study group patients for age and sex. All comorbidity variables and vitiligo diagnoses were extracted from ICD-10 codes that were given prior to a diagnosis of COVID-19. We then constructed multivariable logistic regression models adjusting for measured confounders to evaluate if vitiligo was associated with higher risk for COVID-19 infection after January 1, 2020.

The vitiligo and nonvitiligo cohorts included 40,363 and 161,452 patients, respectively (Table 1). Logistic regression analysis with adjustment for confounding variables, including high comorbid risk factors (Table 2) revealed that patients with a diagnosis of vitiligo had significantly increased odds of COVID-19 infection compared with patients without vitiligo (adjusted odds ratio [AOR], 1.47; 95% CI, 1.37-1.57; P<.001)(Table 3). Additionally, subgroup logistic analyses for sex, age, and exclusion of patients who were HIV positive revealed that females with vitiligo had higher odds of contracting COVID-19 than males with vitiligo (Table 3).

CT113004030_Table1.jpg

Our results showed that patients with vitiligo had a higher relative risk for contracting COVID-19 than individuals without vitiligo. It has been reported that the prevalence of COVID-19 is higher among patients with autoimmune diseases compared to the general population.³ Additionally, a handful of vitiligo patients are managed with immunosuppressive agents that may further weaken their immune response.¹ Moreover, survey results from dermatologists managing vitiligo patients revealed that physicians were fairly comfortable prescribing immunosuppressants and encouraging in-office phototherapy during the COVID-19 pandemic.⁴ As a result, more patients may have been attending in-office visits for their phototherapy, which may have increased their risk for COVID-19. Although these factors play a role in ­COVID-19 infection rates, the underlying immune dysregulation in vitiligo in relation to COVID-19 remains unknown and should be further explored.

CT113004030_Table2.jpg

Our findings are limited by the use of ICD-10 codes, the inability to control for all potential confounding variables, the lack of data regarding the stage of vitiligo, and the absence of data for undiagnosed COVID-19 infections. In addition, patients with vitiligo may be more likely to seek care, potentially increasing their rates of COVID-19 testing. The inability to identify the stage of vitiligo during enrollment in the database may have altered our results, as individuals with active disease have increased levels of IFN-γ. Increased secretion of IFN-γ also potentially helps in the clearance of COVID-19 infection.¹ Future studies should investigate this relationship via planned ­COVID-19 testing, identification of vitiligo stage, and controlling for other associated comorbidities.

CT113004030_Table3.jpg

To the Editor:

Vitiligo is a depigmentation disorder that results from the loss of melanocytes in the epidermis.¹ The most widely accepted pathophysiology for melanocyte destruction in vitiligo is an autoimmune process involving dysregulated cytokine production and autoreactive T-cell activation.¹ Individuals with cutaneous autoinflammatory conditions currently are vital patient populations warranting research, as their susceptibility to COVID-19 infection may differ from the general population. We previously found a small increased risk for COVID-19 infection in patients with psoriasis,² which suggests that other dermatologic conditions also may impact COVID-19 risk. The risk for COVID-19 infection in patients with vitiligo remains largely unknown. In this retrospective cohort study, we investigated the risk for COVID-19 infection in patients with vitiligo compared with those without vitiligo utilizing claims data from the COVID-19 Research Database (https://covid19researchdatabase.org/).

Claims were evaluated for patients aged 3 years and older with a vitiligo diagnosis (International Classification of Diseases, Tenth Revision [ICD-10] code L80) that was made between January 1, 2016, and January 1, 2020. Individuals without a vitiligo diagnosis during the same period were placed (4:1 ratio) in the control group and were matched with study group patients for age and sex. All comorbidity variables and vitiligo diagnoses were extracted from ICD-10 codes that were given prior to a diagnosis of COVID-19. We then constructed multivariable logistic regression models adjusting for measured confounders to evaluate if vitiligo was associated with higher risk for COVID-19 infection after January 1, 2020.

The vitiligo and nonvitiligo cohorts included 40,363 and 161,452 patients, respectively (Table 1). Logistic regression analysis with adjustment for confounding variables, including high comorbid risk factors (Table 2) revealed that patients with a diagnosis of vitiligo had significantly increased odds of COVID-19 infection compared with patients without vitiligo (adjusted odds ratio [AOR], 1.47; 95% CI, 1.37-1.57; P<.001)(Table 3). Additionally, subgroup logistic analyses for sex, age, and exclusion of patients who were HIV positive revealed that females with vitiligo had higher odds of contracting COVID-19 than males with vitiligo (Table 3).

CT113004030_Table1.jpg

Our results showed that patients with vitiligo had a higher relative risk for contracting COVID-19 than individuals without vitiligo. It has been reported that the prevalence of COVID-19 is higher among patients with autoimmune diseases compared to the general population.³ Additionally, a handful of vitiligo patients are managed with immunosuppressive agents that may further weaken their immune response.¹ Moreover, survey results from dermatologists managing vitiligo patients revealed that physicians were fairly comfortable prescribing immunosuppressants and encouraging in-office phototherapy during the COVID-19 pandemic.⁴ As a result, more patients may have been attending in-office visits for their phototherapy, which may have increased their risk for COVID-19. Although these factors play a role in ­COVID-19 infection rates, the underlying immune dysregulation in vitiligo in relation to COVID-19 remains unknown and should be further explored.

CT113004030_Table2.jpg

Our findings are limited by the use of ICD-10 codes, the inability to control for all potential confounding variables, the lack of data regarding the stage of vitiligo, and the absence of data for undiagnosed COVID-19 infections. In addition, patients with vitiligo may be more likely to seek care, potentially increasing their rates of COVID-19 testing. The inability to identify the stage of vitiligo during enrollment in the database may have altered our results, as individuals with active disease have increased levels of IFN-γ. Increased secretion of IFN-γ also potentially helps in the clearance of COVID-19 infection.¹ Future studies should investigate this relationship via planned ­COVID-19 testing, identification of vitiligo stage, and controlling for other associated comorbidities.

CT113004030_Table3.jpg