INTRODUCTION
Atopic dermatitis (AD) is a chronic and burdensome inflammatory skin disease. Classically, AD is characterized as a relapsing, itchy, red, rash with a predilection for skin flexures, presenting mainly in childhood before “burning out†by adulthood. This narrow and overly simplified description overlooks the heterogeneity of AD. AD lesions have differing morphologies (eg, prurigo nodules, lichenoid papules, follicular eczema) and distributions (eg, extensor, head/neck, hand/foot).1 While itch is the most prevalent and burdensome symptom of AD,2,3 skin-pain is one of several other symptoms that contribute to disease-burden.4,5 The course of AD is not homogenous – incidence, chronicity, and persistence vary widely over time.6 This complex constellation of features poses physical, emotional, and psychosocial burden that contributes to reduced quality-of-life (QOL).7,8 Herein, we review clinical domains contributing to AD heterogeneity and discuss how balanced consideration of these aspects can improve AD management.
Skin Manifestations
The notion of a pathognomonic morphology and distribution of skin signs in AD, ie eczematous patches/plaques favoring flexural skin, has long been taught in dermatology. This view of AD is outdated, derived from older literature and anecdotal clinical experience of disease presentation in individuals of white race and Northern European ancestry, and ignores major differences in lesional morphology, distribution, and extent. Clinical presentation of AD varies widely across geographic regions, age,9-11 ethnicity,12 and underlying immunopathogenesis,13 suggesting genetics14 and environment15 contribute to disease heterogeneity.
A systematic review and meta-analysis of 101 observational studies published from 1984–2017 underscored many regional and age-related differences in skin manifestations of AD.1 Overall, lesions were distributed most commonly on flexural sites (58%), followed by extensor surface of upper extremities (51%), head, face, and neck (42%), hands and feet (36%), scalp (34%), and extensor surface of lower limbs (25%). Flexural involvement was more common in Australia, followed by Africa, Southeast Asia (SEA), East Asia (EA), and Europe, and less common in the Americas and Iran. Extensor lesions were most common in India, Iran, and EA. Head, face, and neck involvement was more common in Iran, Africa, and the Americas, and least common in SEA. Compared to European studies, truncal, extensor, scalp, and auricular involvement was more common in EA; head, face, and neck involvement was more common in Iran. Moreover, commonly reported morphological characteristics included perifollicular accentuation (follicular eczema; 34%), papular lichenoid (22%), nummular (13%), and prurigo lesions (7%). Papular lichenoid lesions, palmar hyperlinearity, orbital darkening, and ichthyosis were more prevalent in Africa. Dermatitis of eyelids, auricle, and ventral wrist, exudative eczema, and seborrheic dermatitis-like
Skin Manifestations
The notion of a pathognomonic morphology and distribution of skin signs in AD, ie eczematous patches/plaques favoring flexural skin, has long been taught in dermatology. This view of AD is outdated, derived from older literature and anecdotal clinical experience of disease presentation in individuals of white race and Northern European ancestry, and ignores major differences in lesional morphology, distribution, and extent. Clinical presentation of AD varies widely across geographic regions, age,9-11 ethnicity,12 and underlying immunopathogenesis,13 suggesting genetics14 and environment15 contribute to disease heterogeneity.
A systematic review and meta-analysis of 101 observational studies published from 1984–2017 underscored many regional and age-related differences in skin manifestations of AD.1 Overall, lesions were distributed most commonly on flexural sites (58%), followed by extensor surface of upper extremities (51%), head, face, and neck (42%), hands and feet (36%), scalp (34%), and extensor surface of lower limbs (25%). Flexural involvement was more common in Australia, followed by Africa, Southeast Asia (SEA), East Asia (EA), and Europe, and less common in the Americas and Iran. Extensor lesions were most common in India, Iran, and EA. Head, face, and neck involvement was more common in Iran, Africa, and the Americas, and least common in SEA. Compared to European studies, truncal, extensor, scalp, and auricular involvement was more common in EA; head, face, and neck involvement was more common in Iran. Moreover, commonly reported morphological characteristics included perifollicular accentuation (follicular eczema; 34%), papular lichenoid (22%), nummular (13%), and prurigo lesions (7%). Papular lichenoid lesions, palmar hyperlinearity, orbital darkening, and ichthyosis were more prevalent in Africa. Dermatitis of eyelids, auricle, and ventral wrist, exudative eczema, and seborrheic dermatitis-like
