Immunology and AllergyTier 1Disease (DEADMAN)

Allergic disorders - atopic dermatitis (eczema)

Description

Chronic relapsing-remitting inflammatory skin disease with impaired epidermal barrier function
Part of the atopic march - often precedes food allergy, allergic rhinitis, and asthma in childhood

Filaggrin gene mutations - impaired skin barrier -> transepidermal water loss + allergen/microbial penetration
Th2-skewed immune response - IL-4, IL-13, IL-31 drive inflammation and pruritus (targets of current biologics)
Barrier disruption -> colonisation/infection with Staphylococcus aureus -> further inflammation ("itch-scratch cycle")
Trigger factors: irritants (soap, wool), heat/sweat, aeroallergens, food allergens (esp. infants with moderate-severe disease), stress, dry climate

Clinical

Pruritus (always present) + typical morphology/distribution by age:
- Infants - face, scalp, extensor surfaces
- Children/adults - flexural (antecubital/popliteal fossae), neck, hands
Chronic/relapsing course, personal/family history of atopy
Severity scoring (e.g. SCORAD, EASI) for treatment escalation decisions

Investigations - rarely needed for diagnosis

Consider allergy testing (skin prick/specific IgE) if food allergy suspected as a trigger in infants with moderate-severe disease, or for concurrent aeroallergen-driven disease
Skin swab if secondary bacterial infection suspected

By severity - stepwise

### All severities - foundational

Regular emollient use (liberal, frequent) - reduces flares and topical steroid requirement
Avoid known triggers/irritants, lukewarm short showers, soap substitutes

### Mild-moderate

Topical corticosteroids - potency matched to site/severity (low potency for face/flexures, higher for thickened plaques), used for flares, stepped down once controlled
Topical calcineurin inhibitors (tacrolimus, pimecrolimus) - steroid-sparing, useful for face/flexures and maintenance ("proactive" twice-weekly use to prevent relapse)

### Moderate-severe, refractory to topical therapy

Dupilumab (anti-IL-4Ra) - first-line biologic, strong evidence base, approved from age 6 months in many jurisdictions
Tralokinumab (anti-IL-13) - alternative biologic, fewer ocular side effects than dupilumab
JAK inhibitors (upadacitinib, abrocitinib) - oral option for refractory disease or when biologics inadvisable/failed; faster onset than biologics but carry a boxed warning (VTE, MACE, malignancy, infection) - reserve for refractory cases after risk discussion
Phototherapy (narrowband UVB) - alternative for widespread disease without access to systemic agents
Short courses of oral corticosteroids - avoid as a long-term strategy (rebound flare on cessation)

### Secondary infection

Treat overt bacterial infection (topical/oral antibiotics targeting S. aureus); routine antibiotic/antiseptic use for colonisation alone is not recommended
Eczema herpeticum (rapidly spreading vesicles, punched-out erosions, systemic illness) - same-day dermatology/ID referral, IV aciclovir

Atopic march - food allergy, allergic rhinitis, asthma
Secondary bacterial (S. aureus) and viral (eczema herpeticum, molluscum) skin infection
Sleep disturbance, psychological impact (anxiety, depression), impaired quality of life
Ocular complications with dupilumab specifically (conjunctivitis, keratitis) - counsel and monitor

Many children improve/resolve by adolescence; a significant minority have persistent or adult-onset disease
Severity fluctuates with environmental triggers, infection, and stress
Early effective control may reduce (though does not eliminate) progression along the atopic march
Biologics/JAK inhibitors have substantially improved outcomes for the moderate-severe refractory population previously limited to immunosuppressants (ciclosporin, methotrexate) or phototherapy alone

6 more sections, plus exam facts

Premium unlocks every note across every specialty, and the full exam fact library behind it.