Atopic Dermatitis (Pediatric)

Definition

Atopic dermatitis (AD) is a chronic, relapsing inflammatory skin disorder in children, characterized by pruritus, eczematous lesions, and a personal or family history of atopy.

Epidemiology

• Most common chronic skin disease in children, affecting 10–20% worldwide
• Typically presents in infancy or early childhood; up to 60% develop symptoms in the first year
• Higher prevalence in developed countries and urban areas
• Family history of atopy (asthma, allergic rhinitis) is a strong risk factor
• Often associated with the 'atopic march' leading to asthma or allergic rhinitis later

Etiology

• Genetic predisposition: filaggrin gene mutations impair skin barrier function
• Immune dysregulation: Th2-skewed inflammatory response
• Environmental triggers: allergens (dust mites, pollen), irritants (soaps, detergents), climate changes
• Microbial colonization: Staphylococcus aureus colonization exacerbates flares
• Food allergies can trigger or worsen symptoms in infants and young children
• Emotional stress may aggravate disease

Pathophysiology

• Defective skin barrier leads to increased transepidermal water loss and allergen penetration
• Immune dysregulation causes chronic inflammation, dominated by Th2 cytokines
• Pruritus results in scratching, further damaging the skin and perpetuating inflammation (itch-scratch cycle)
• Microbial colonization, especially S. aureus, exacerbates inflammation
• Chronic lesions show lichenification and epidermal hyperplasia
• Progression may lead to atopic march: asthma and allergic rhinitis