What is atopic dermatitis?

Atopic Dermatitis: Comprehensive Overview

Atopic dermatitis is a chronic, pruritic inflammatory skin disease characterized by relapsing eczematous lesions, skin barrier dysfunction, and immune dysregulation that significantly impacts quality of life through persistent itching and inflammation. 1

Definition and Epidemiology

• Atopic dermatitis (AD), also known as atopic eczema, is a chronic inflammatory skin condition that follows a relapsing course, occurring most frequently in children but also affecting adults 1
• AD onset typically occurs between 3-6 months of age, with approximately 60% developing symptoms in the first year of life and 90% by 5 years of age 1
• Prevalence has increased dramatically in recent decades, affecting 10-20% of children and 2-3% of adults worldwide 1
• While most affected individuals experience resolution by adulthood, 10-30% continue to have persistent disease, and some develop symptoms for the first time as adults 1

Pathophysiology

• AD results from complex interactions between genetic factors, environmental exposures, skin barrier dysfunction, and immunological derangement 1, 2
• Two primary mechanisms contribute to disease development:
  • "Outside-in" theory: Epidermal barrier defects allow allergens and irritants to penetrate the skin 1, 2
  • "Inside-out" theory: Immune dysregulation triggers inflammation that compromises skin barrier function 1, 2
• Skin barrier abnormalities include:
  • Filaggrin mutations leading to impaired epidermal differentiation 2, 3
  • Defects in stratum corneum constituents and tight junctions 2
  • Increased transepidermal water loss 1
• Immunological features include:
  • T-helper 2 (Th2) cell predominance with elevated IgE levels 1, 3
  • Increased inflammatory cytokines (IL-2, IL-31) that drive pruritus 1
  • Skin microbiome dysbiosis contributing to inflammation 3

Clinical Presentation and Diagnosis

• The diagnosis of AD is made clinically based on historical features, morphology and distribution of skin lesions, and associated clinical signs 1
• Key clinical features include:
  • Intense pruritus (a hallmark symptom) 1
  • Eczematous lesions with age-specific distribution patterns 1
  • Chronic or relapsing disease course 1
  • Personal or family history of atopy (allergic rhinitis, asthma, food allergies) 1
• Clinical findings vary by age and chronicity:
  • Erythema, edema, xerosis (dry skin), erosions/excoriations, oozing, crusting, and lichenification 1
  • Infantile AD (0-2 years): Typically affects the face, scalp, and extensor surfaces 1
  • Childhood AD (2-12 years): Flexural areas (antecubital and popliteal fossae) 1
  • Adult AD: Flexural areas, hands, and face with more lichenification 1, 4
• Diagnostic criteria include the Hanifin and Rajka criteria (requiring 3 of 4 major criteria and 3 of 23 minor criteria) and the UK Working Party criteria (more streamlined for clinical use) 1

Disease Associations and Complications

• AD is associated with several comorbidities:
  • Allergic conditions: Asthma, allergic rhinitis, and food allergies (part of the "atopic march") 1, 5
  • Sleep disturbances: 60% of children with AD experience sleep disruption, with 83% reporting sleep disturbance during exacerbations 1
  • Psychological impacts: Increased risk of anxiety, depression, and attention deficit hyperactivity disorder 5
• Complications include:
  • Skin infections: Increased susceptibility to bacterial (especially Staphylococcus aureus), viral, and fungal infections 4
  • Growth impairment: Short stature has been described in children with AD when associated with insufficient sleep 1
  • Quality of life impairment: Significant impact on social functioning, school/work performance, and interpersonal relationships 1, 5

Management Approaches

Non-pharmacological Interventions

• Skin hydration and barrier repair:
  • Regular use of emollients/moisturizers is essential for all patients regardless of disease severity 1
  • Apply moisturizers immediately after bathing (within 3 minutes of a 10-15 minute lukewarm bath) 1
  • Emollients can lengthen time to disease flares compared to no treatment 1
• Trigger avoidance:
  • Identify and avoid individual triggers (certain fabrics, detergents, foods, environmental allergens) 1
  • Use fragrance-free products and wear smooth, non-irritating clothing 1

Topical Therapies

• Topical corticosteroids (TCS):
  • First-line therapy for acute flares, applied once or twice daily until significant improvement 1
  • Potency selection based on patient age, body location, and disease severity 1
  • Lower potency for face, neck, and intertriginous areas; higher potency for trunk and extremities 1
  • Proactive therapy with twice-weekly application of low to medium potency TCS to previously affected areas can prevent relapses 1
• Topical calcineurin inhibitors (TCIs):
  • Steroid-sparing agents (tacrolimus ointment, pimecrolimus cream) 1, 6
  • Particularly useful for sensitive areas (face, neck, intertriginous areas) 1
  • Pimecrolimus cream 1% has shown efficacy in mild to moderate AD in children 2 years and older 6
• Wet-wrap therapy:
  • Effective short-term second-line treatment for moderate to severe AD 1
  • Promotes transepidermal penetration of topical medications and prevents scratching 1
  • Recommended for 3-7 days, with possible extension to 14 days in severe cases 1

Phototherapy and Systemic Treatments

• Phototherapy:
  • Recommended for both acute and chronic AD after failure of topical therapies 1
  • Various modalities include narrowband UVB, broadband UVB, and UVA1 1
• Systemic immunomodulatory agents:
  • Indicated for patients in whom optimized topical regimens and/or phototherapy do not adequately control disease 1
  • Options include cyclosporine, methotrexate, azathioprine, and mycophenolate mofetil 1
  • Newer targeted therapies include dupilumab (IL-4/IL-13 inhibitor) and JAK inhibitors 3

Prevention and Long-term Management

• Proactive therapy approach:
  • Maintenance treatment with intermittent anti-inflammatory therapy (TCS or TCI) to prevent flares 1
  • Regular use of moisturizers even during disease-free periods 1
• Early intervention:
  • Early and aggressive treatment of flares to prevent chronicity 1
  • Addressing skin barrier dysfunction may prevent subsequent development of other atopic conditions 1
• Emerging preventive strategies:
  • Skin barrier enhancement from birth in high-risk infants 7
  • Probiotics, prebiotics, and synbiotics (evidence still evolving) 7
  • Vitamin D supplementation (mixed evidence) 7

Common Pitfalls in Management

• Inadequate moisturizer use: Moisturizers should be applied liberally and frequently (at least twice daily) 1
• Corticosteroid phobia: Fear of side effects leading to undertreatment; proper education about appropriate use is essential 1
• Overlooking infections: Secondary bacterial and viral infections require prompt recognition and treatment 4
• Focusing only on skin symptoms: Addressing sleep disturbances, psychological impacts, and quality of life is crucial 1, 5
• Discontinuing treatment too early: Maintenance therapy is often needed to prevent rapid relapse 1