The Clinical Diversity of Atopic Dermatitis
Atopic dermatitis (AD) is a common chronic inflammatory skin condition associated with diverse cutaneous presentations. Differences in clinical phenotypes in skin of color (SOC) patients with AD have been previously noted in race-based analyses. We conducted a narrative review to better characterize the clinical diversity of AD and understand these differences in the context of race, ethnicity, and SOC. Notable racial and ethnic differences in clinical phenotypes have been observed; however, these analyses often are limited by deeper understanding of the true causative factors driving observed differences. Dermatologists should be familiar with the heterogeneity of AD lesional morphology and inflammation severity across all skin types.
Practice Points
- Social determinants of health play a central role in observed racial and ethnic differences in studies of atopic dermatitis (AD) in patients with skin of color.
- Prurigo nodules, lichenoid papules, perifollicular papules, nummular lesions, and psoriasiform lesions are among the diverse lesion morphologies seen with AD.
- Key signs of cutaneous inflammation and lesional severity, including erythema, may present differently in darker skin tones and contribute to underestimation of severity.
- Postinflammatory dyspigmentation is common among patients with skin of color, and treatment can substantially improve quality of life.
Disease Severity
Several factors contribute to AD disease severity,34 including objective assessments of inflammation, such as erythema and lichenification (Table), as well as subjective measures of symptoms, such as itch. The severity of AD is exacerbated by the social determinants of health, and a lower socioeconomic status, lower household income, lower parental education level and health, dilapidated housing, and presence of garbage on the street are among factors linked to worse AD disease severity.13,17 Although non-White individuals with AD often are reported to have more severe disease than their White counterparts,35 these types of health determinants may be the most relevant causes of observed differences.
Erythema—Erythema is a feature of inflammation used in the AD severity assessment. Erythema may appear in shades beyond red, including maroon, violaceous, or brown, in patients with darker pigmented skin, which may contribute to diagnosis of AD at a later disease stage.26 Multiple AD severity scoring tools, such as the SCORing Atopic Dermatitis and Eczema Area and Severity Index, include erythema as a measure, which can lead to underestimation of AD severity in SOC populations. After adjusting for erythema score, one study found that Black children with AD had a risk for severe disease that was 6-times higher than White children.36 Dermatological training must adequately teach physicians to recognize erythema across all skin tones.37
Erythroderma (also known as exfoliative dermatitis) is rapidly spreading erythema on at least 90% of the total body surface area, often sparing the palms and soles.32 Erythroderma is a potentially life-threatening manifestation of severe AD. Although erythroderma may have many underlying causes, AD has been reported to be the cause in 5% to 24% of cases,38 and compared to studies in Europe, the prevalence of erythroderma was higher in East Asian studies of AD.28
Excoriation and Pruritus—Pruritus is a defining characteristic of AD, and the resulting excoriations often are predominant on physical examination, which is a key part of severity scores. Itch is the most prevalent symptom among patients with AD, and a greater itch severity has been linked to decreased health-related quality of life, increased mental health symptoms, impaired sleep, and decreased daily function.39,40 The burden of itch may be greater in SOC populations. The impact of itch on quality of life among US military veterans was significantly higher in those who identified as non-White (P=.05).41 In another study of US military veterans, African American individuals reported a significantly higher emotional impact from itch (P<.05).42
Lichenification—Lichenification is thickening of the skin due to chronic rubbing and scratching that causes a leathery elevated appearance with exaggerated skin lines.27 Lichenification is included as a factor in common clinical scoring tools, with greater lichenification indicating greater disease severity. Studies from SEA and Africa suggested a higher prevalence of lichenification in AD patients.28 A greater itch burden and thus increased rubbing/scratching in these populations may contribute to some of these findings.42,43
Xerosis—Xerosis (or dry skin) is a common finding in AD that results from increased transepidermal water loss due to a dysfunctional epidermal barrier.44 In a systematic review of AD characteristics by region, xerosis was among the top 5 most reported AD features globally in all regions except SEA.28 Xerosis may be more stigmatizing in SOC populations because of the greater visibility of scaling and dryness on darker skin tones.1
Postinflammatory Dyspigmentation—Postinflammatory pigment alteration may be a consequence of AD lesions, resulting in hyperpigmented and hypopigmented macules and patches. Patients with AD with darker skin tones are more likely to develop postinflammatory dyspigmentation.26 A study of AD patients in Nigeria found that 63% displayed postinflammatory dyspigmentation.45 Dyschromia, including postinflammatory hyperpigmentation, is one of the most common reasons for SOC patients to seek dermatologic care.46 Postinflammatory pigment alteration can cause severe distress in patients, even more so than the cutaneous findings of AD. Although altered skin pigmentation usually returns to normal over weeks to months, skin depigmentation from chronic excoriation may be permanent.26 Appropriately treating hyperpigmentation and hypopigmentation in SOC populations can greatly improve quality of life.47
Conclusion
Atopic dermatitis is a cutaneous inflammatory disease that presents with many clinical phenotypes. Dermatologists should be trained to recognize the heterogeneous signs of AD present across the diverse skin types in SOC patients. Future research should move away from race-based analyses and focus on the complex interplay of environmental factors, social determinants of health, and skin pigmentation, as well as how these factors drive variations in AD lesional morphology and inflammation.
