Atopic Dermatitis

Atopic dermatitis, commonly known as eczema, is a chronic inflammatory skin condition characterized by intensely itchy, red, and inflamed skin patches that follow a relapsing-remitting course (periods of flares alternating with calm periods). The condition results from a complex interplay of genetic factors affecting skin barrier function, immune system dysfunction favoring allergic responses (type 2 inflammation), and environmental triggers.

Atopic dermatitis affects over 200 million people worldwide, with higher prevalence in children than adults and in developed nations.

• Prevalence: Affects 1 in 25 children (4%) and 1 in 50 adults (2%) globally; in resource-rich countries, up to 1 in 10 people (9.2%) experience symptoms annually
• Age demographics: Onset before age 5 in 90% of cases; 60% develop symptoms in first year of life; approximately 1 in 5 cases (20%) persist into adulthood
• Gender distribution: Slightly more common in females (2.8%) than males (2.4%); females more likely to have persistent disease into adulthood
• Risk factors: Family history of atopic conditions (eczema, asthma, hay fever); filaggrin gene mutations (present in 30% of patients); living in developed countries (hygiene hypothesis); urban environment; higher socioeconomic status

Atopic dermatitis presents differently across age groups but shares common features of itch and inflammation:

• Infantile pattern (0-2 years): Red, weeping, crusted patches on cheeks, scalp, and extensor surfaces (outer arms and legs); typically spares diaper area; may appear as cradle cap on scalp
• Childhood pattern (2-12 years): Dry, thickened (lichenified) patches in flexural areas - inner elbows (antecubital fossae), behind knees (popliteal fossae), neck, wrists, ankles; skin becomes leathery from chronic scratching
• Adult pattern: Flexural involvement continues; hand and foot eczema common; eyelid dermatitis; may develop prurigo nodularis (extremely itchy bumps)
• Associated features: Intense pruritus (itching) - hallmark symptom, often worse at night; dry skin (xerosis) even in unaffected areas; Dennie-Morgan folds (extra creases under eyes); keratosis pilaris (rough bumps on arms); increased skin infections due to impaired barrier
• Disease course: Chronic condition with unpredictable flares; triggers include stress, allergens, irritants, infections, weather changes; severity ranges from mild patches to widespread involvement affecting quality of life

Atopic dermatitis results from multiple interacting factors affecting skin barrier and immune function:

• Skin barrier dysfunction: Filaggrin gene mutations reduce natural moisturizing factors in skin; impaired barrier allows water loss (dry skin) and allergen/irritant penetration; disrupted skin microbiome with Staphylococcus aureus overgrowth in 90% of affected skin
• Immune dysregulation: Overactive type 2 immune response with elevated IgE antibodies; increased inflammatory cytokines (IL-4, IL-13, IL-31); IL-31 specifically triggers itch sensation; chronic inflammation leads to skin thickening
• Environmental triggers: Allergens (dust mites, pet dander, pollen); irritants (soaps, detergents, fragrances, wool); climate factors (low humidity, temperature extremes); psychological stress; hormonal changes
• Genetic predisposition: Strong hereditary component - 70% have family history; multiple susceptibility genes identified; earlier onset typically indicates stronger genetic component

Diagnosis is clinical, based on characteristic features and history:

• Diagnostic criteria: Major criterion - pruritus (essential for diagnosis); typical morphology and distribution for age; chronic or relapsing course; personal or family history of atopy (eczema, asthma, allergic rhinitis)
• Severity assessment tools: EASI score (Eczema Area and Severity Index) - objective measure of extent and severity; SCORAD - combines objective signs with subjective symptoms; mild (<10% body surface area), moderate (10-50%), severe (>50%)
• Laboratory tests: Usually unnecessary for diagnosis; elevated IgE in 80% but not required; specific IgE testing if food allergy suspected (especially in infants); patch testing for contact allergens in chronic hand/foot eczema
• Differential diagnosis: Must distinguish from seborrheic dermatitis (greasy scales, different distribution); contact dermatitis (clear trigger, localized); psoriasis (well-demarcated plaques with silvery scale); scabies (interdigital involvement, family affected)

Treatment follows a stepwise approach based on severity, with skin hydration as the foundation:

• Basic skin care (all severities): Liberal emollient application 2-4 times daily, especially after bathing; fragrance-free, ceramide-containing moisturizers optimal; lukewarm baths with gentle cleansers; pat dry, apply emollient within 3 minutes
• Topical anti-inflammatories (mild-moderate): Topical corticosteroids - first-line for flares, use lowest effective potency; apply thin layer once or twice daily during flares; topical calcineurin inhibitors (tacrolimus, pimecrolimus) - steroid-sparing option for face and skin folds; newer options include crisaborole (PDE4 inhibitor) and ruxolitinib (JAK inhibitor)
• Systemic treatments (moderate-severe): Dupilumab (IL-4/IL-13 blocker) - injectable biologic, first-line systemic therapy with excellent safety; 60-70% achieve significant improvement; JAK inhibitors (upadacitinib, abrocitinib) - oral medications with rapid onset but require monitoring; traditional immunosuppressants (cyclosporine, methotrexate) for short-term use
• Adjunctive therapies: Dilute bleach baths twice weekly for recurrent infections; wet wrap therapy for severe flares; phototherapy (UV light) 2-3 times weekly; antihistamines for nighttime itch relief
• Expected outcomes: Most childhood eczema improves with age - 50% clear by school age, 80% by 8 years; approximately 20% have persistent disease into adulthood; early aggressive treatment may alter disease course; flare prevention with proactive therapy (intermittent anti-inflammatories on previously affected areas)

• Atopic dermatitis is a chronic condition requiring consistent daily skin care, not just treatment during flares
• The "itch-scratch cycle" perpetuates the condition - managing itch is crucial for healing
• Many children outgrow eczema, though some develop asthma or allergies (atopic march)
• When to seek medical attention: Signs of skin infection (yellow crusting, fever, spreading redness); severe flares not responding to usual treatment; significant sleep disruption or quality of life impact; suspected eczema herpeticum (widespread painful vesicles)
• Prevention strategies: Identify and avoid personal triggers; maintain consistent moisturizing routine; manage stress through relaxation techniques; keep fingernails short to minimize scratch damage; consider psychological support for chronic disease impact