DermatologyTier 1Disease (DEADMAN)

Dermatitis - atopic (eczema)

Description

Chronic relapsing-remitting inflammatory dermatosis - itch is the defining symptom ("the itch that rashes")
Distribution changes with age: infants - face/extensor surfaces; children/adults - flexural (antecubital, popliteal fossae)

~15-20% of children, often improving/resolving by adolescence; ~2-5% of adults (persistent or adult-onset)
Part of the atopic triad with asthma and allergic rhinitis - often familial

Filaggrin gene mutations -> impaired skin barrier function -> increased transepidermal water loss and allergen penetration
Th2-skewed immune response - IL-4, IL-13, IL-31 drive inflammation and itch
Barrier dysfunction + dysbiosis (S. aureus colonisation common) + environmental triggers (irritants, allergens, climate) perpetuate the itch-scratch cycle

Clinical - itch plus typical morphology/distribution, chronic/relapsing course, personal/family atopy history
UK Working Party diagnostic criteria commonly used - itchy skin plus 3+ of: flexural involvement, history of asthma/hay fever, dry skin in the past year, onset before age 2, visible flexural dermatitis
Patch testing if allergic contact dermatitis is suspected as a co-existing/complicating factor

By severity - stepped approach

Basics for all severities: regular emollients (liberal, frequent), soap substitutes, trigger avoidance, bathing/moisturising routine
Mild-moderate: topical corticosteroids matched to site/severity (lower potency for face/flexures), topical calcineurin inhibitors (tacrolimus, pimecrolimus) - steroid-sparing, useful for face/eyelids
Moderate-severe, refractory to topical therapy: dupilumab (anti-IL-4/13) - established targeted biologic, PBS-listed for eligible patients; other biologics (tralokinumab) and JAK inhibitors (upadacitinib, abrocitinib) increasingly used
Infected eczema: treat clinically infected areas with antiseptic/topical or oral antibiotics targeting S. aureus
Eczema herpeticum (widespread punched-out vesicles, systemic upset) - dermatological/medical emergency, needs oral/IV aciclovir

Most childhood atopic dermatitis improves substantially by adolescence; a minority persists into/relapses in adulthood
Chronic scratching leads to lichenification over time
Biologic therapy has substantially improved outcomes for the moderate-severe refractory subgroup previously limited to systemic immunosuppressants

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