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Atopic Dermatitis

John Montgomery7 min read

Atopic Dermatitis

Definition. The American Academy of Dermatology defines atopic dermatitis (AD) as “a chronic, pruritic inflammatory skin disease that occurs most frequently in children, but can also affect adults”, following a relapsing course and often linked to raised IgE and a personal or family history of Asthma, Allergic Rhinitis and other type I allergies; “atopic eczema” is a synonym (AAD 2014). Itch is the hallmark and drives most of the burden on children and families. DermNet describes it as the most common inflammatory skin disease worldwide (~230 million people), arising from an interplay of genetic factors, such as loss-of-function variants in Filaggrin, and environmental factors that together produce a leaky skin barrier and immune dysregulation. Infection is the main acute complication: crusted, weeping flares often involve Staphylococcus aureus, and Eczema Herpeticum (widespread herpes simplex) needs same-day specialist referral under NICE CG57.

Filaggrin [relates] Atopic Dermatitis Staphylococcus aureus [worsens] Atopic Dermatitis Eczema Herpeticum [part-of] Atopic Dermatitis Atopic Dermatitis [relates] Asthma

Presentation by age: infant vs toddler. Per AAD, onset is most common at 3–6 months: ~60% start in the first year and ~90% by age 5. In infants, AD often starts on the scalp and cheeks/face and can be extensive on the trunk. The nappy area is usually spared because it stays moist, and babies rub rather than scratch (DermNet). Once a child crawls, it moves to the extensor surfaces of elbows, wrists, knees and ankles. With walking (the 1–4 toddler window), it shifts to the flexures: elbow creases (antecubital), behind the knees (popliteal), plus wrists and ankles. Dribble and food cause perioral/chin dermatitis, and chronic scratching starts to produce lichenification (thickened, leathery skin) (DermNet). NICE warns that in Asian, Black Caribbean and Black African children, extensor, discoid or follicular patterns may predominate over flexural ones. Adults differ again: flexural or diffuse disease, hand dermatitis, nodular prurigo, and some adult-onset cases.

Atopic Dermatitis [precedes] Lichenification NICE CG57 [defines] Atopic Dermatitis

Diagnosis. AD is a clinical diagnosis, with no lab test required (AAD 2014; DermNet). The Hanifin-Rajka Criteria (1980) need 3 of 4 major plus 3 of 23 minor features. They are thorough but unwieldy, so they are mainly used in trials. The UK Working Party Criteria distil these into 1 mandatory and 5 major criteria that non-dermatologists can use, and both sets are validated (AAD 2014). NICE CG57 uses the UK Working Party form: an itchy skin condition plus ≥3 of the following:

  • visible flexural dermatitis (or cheeks/extensors if ≤18 months)
  • a history of flexural dermatitis
  • dry skin in the last 12 months
  • asthma or allergic rhinitis (or atopic disease in a first-degree relative if <4 years)
  • onset before age 2 (not used in children under 4)

For toddlers this means a 1–4-year-old is diagnosed mainly on itch, flexural rash, dry skin and family history.

UK Working Party Criteria [defines] Atopic Dermatitis Hanifin-Rajka Criteria [defines] Atopic Dermatitis UK Working Party Criteria [part-of] Hanifin-Rajka Criteria NICE CG57 [supports] UK Working Party Criteria

Severity scoring. NICE grades physical severity as clear, mild, moderate or severe, and grades quality-of-life impact separately. It stresses that the two may not match, and suggests POEM plus 0–10 visual analogue scales for itch and sleep loss. SCORAD = A/5 + 7B/2 + C. A is the extent (% of body), B is 6 intensity signs each scored 0–3, and C is itch plus sleeplessness on visual analogue scales (VAS), rated by the parent for toddlers. EASI (range 0–72) scores area and 4 signs in 4 regions, with child-specific multipliers for ages 0–7 (head/neck ×0.2, legs ×0.3). It ignores dryness. POEM is parent-reported: 7 questions on the past week, total 0–28. Its bands are 0–2 clear, 3–7 mild, 8–16 moderate, 17–24 severe and 25–28 very severe (Nottingham CEBD). For parents tracking a toddler at home, POEM is the practical tool, while SCORAD and EASI are clinician tools. Severity sets the treatment step in NICE CG57: Emollient Therapy always, then Topical Corticosteroids of increasing potency.

SCORAD [defines] Atopic Dermatitis EASI [defines] Atopic Dermatitis POEM [defines] Atopic Dermatitis Emollient Therapy [treats] Atopic Dermatitis Topical Corticosteroids [treats] Atopic Dermatitis

Prevalence, prognosis and the atopic march. AD affects up to 25% of children and 2–3% of adults (AAD 2014). DermNet gives 15–20% of children, and ISAAC phase III gives 7.9% at age 6–7 (Medicina 2024). On outgrowing it, the Kim 2016 meta-analysis (45 studies, 110,651 subjects) found that 80% of childhood AD no longer persisted 8 years after diagnosis and fewer than 5% persisted at 20 years. Onset by age 2 predicted less persistent disease, while later onset, longer duration and greater severity predicted persistence. AAD estimates that 10–30% do not clear by adulthood. Other studies disagree (see conflict below). The Atopic March is the classic sequence of AD and Food Allergy in infancy, followed by Asthma and Allergic Rhinitis. Early-onset, severe and persistent AD, Filaggrin mutations and family atopy all raise this risk: asthma affects ~20% of children with mild AD versus >60% with severe AD. However, latent-class cohort analyses (Belgrave, PLoS Med 2014) show that only 3.1% of all children (~7% of those with any allergic symptoms) follow a true march trajectory, so reviewers now prefer the term “atopic multimorbidity” (Medicina 2024).

Conflict: [Kim et al., JAAD 2016] says 80% of childhood AD has remitted by 8 years after diagnosis and <5% persists at 20 years. [Margolis et al., JAMA Dermatol 2014, PEER registry] says >80% of children aged 2–26 still had symptoms or used treatment, and only half had a 6-month clear spell by age 20. [Abuabara et al., Allergy 2018] found AD prevalence barely falls after age 12 (−1%, not significant). Differences likely reflect outcome definitions (remission vs any symptom-free period) and cohort selection (registry of treated children vs population). Unresolved — add to open_questions.

Conflict: [Classic atopic-march model, e.g. CHILD/PASTURE cohorts cited in Medicina 2024] says early AD leads to later asthma and rhinitis. [Belgrave 2014 latent-class analysis, cited in Medicina 2024] says only ~3.1–7% of children follow that trajectory, and co-occurrence ≠ causation. Unresolved — add to open_questions.

Atopic Dermatitis [precedes] Atopic March Atopic Dermatitis [precedes] Food Allergy Atopic March [precedes] Asthma Atopic March [precedes] Allergic Rhinitis Filaggrin [worsens] Atopic March

Connections

  • NICE CG57 — defines diagnostic criteria and stepped care for under-12s, source: NICE CG57
  • UK Working Party Criteria — defines, source: AAD 2014; NICE CG57
  • Hanifin-Rajka Criteria — defines, source: AAD 2014
  • SCORAD — severity measure, source: DermNet SCORAD
  • EASI — severity measure with child multipliers, source: DermNet EASI
  • POEM — parent-reported severity measure, source: Nottingham CEBD; NICE CG57
  • Filaggrin — genetic risk factor (primary-cause role contested, see Filaggrin note), raises persistence and march risk, source: Medicina 2024; DermNet
  • Staphylococcus aureus — infective complication, source: DermNet; NICE CG57
  • Eczema Herpeticum — emergency complication, source: NICE CG57
  • Food Allergy — co-occurs in infancy, first step of atopic march, source: Medicina 2024
  • Atopic March — precedes; contested model, source: Medicina 2024
  • Asthma — later comorbidity, source: Medicina 2024; AAD 2014
  • Allergic Rhinitis — later comorbidity, source: Medicina 2024
  • Lichenification — chronic scratching sign, source: DermNet
  • Emollient Therapy — first-line treatment, source: NICE CG57
  • Topical Corticosteroids — stepped treatment by severity, source: NICE CG57
  • Aqueous Cream — may worsen AD (irritant), source: MHRA 2013 via Aqueous Cream note
  • Herbal and Home Remedies for Eczema — Track A remedies; 46–63% of children in clinic samples use CAM, source: Johnston 2003; Koo 2020
  • Adulterated Herbal Creams — ‘natural’ eczema creams hiding potent steroids, source: Ramsay ADC 2003; MHRA 2018
  • Allergic Contact Dermatitis — 36.9% of patch-tested AD children have contact allergy vs 26.4% without AD, source: Bonamonte 2022
  • Eczema Prognosis — natural course: 43% of early AD remits by age 3 (MAS); six trajectory classes, source: Illi 2004; Paternoster 2018
  • Eczema in Skin of Colour — violaceous/grey, papular, extensor presentation; severity under-scored, source: Ben-Gashir 2002; NICE CG57
  • Differential Diagnosis of Toddler Eczema — mimics and red flags for immunodeficiency, source: Türe Avcı 2026

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