Atopic Dermatitis Management and Pathophysiology
Definition and Epidemiology
- Atopic dermatitis (AD) is a chronic inflammatory skin disease that follows a relapsing course, occurring most frequently in children but also affecting adults 1
- Approximately 80% of patients develop symptoms within the first 5 years of life 2
- The prevalence has increased dramatically in recent decades, affecting 10-20% of children and 2-3% of adults globally 1
- AD accounts for 10-20% of all referrals to dermatologists and about 30% of dermatological consultations in general practice 3
Pathophysiology
- AD results from complex interactions between genetic factors, environmental exposures, skin barrier dysfunction, and immunological derangement 1
- The mechanisms involve both "outside-in" (skin barrier dysfunction) and "inside-out" (immunologic aberration triggering barrier disruption) pathways 2
- Cross-talk between skin barrier abnormalities and aberrant immune responses is evidenced by epidermal abnormalities enhancing the release of keratinocyte-derived thymic stromal lymphopoietin, which may enhance Th2 cell differentiation 2
Clinical Presentation
- Key clinical features include intense pruritus (itching) 4
- Eczematous lesions that follow a symmetrical and age-specific distribution pattern 2
- Dry skin (xerosis) 3
- Chronic or relapsing disease course 4
- Personal or family history of atopy (asthma, allergic rhinitis) 4
Diagnosis
- AD is diagnosed clinically based on the patient's history, family history, and appearance of the eruption 3, 1
- Diagnostic criteria include an itchy skin condition plus three or more of the following History of itchiness in skin creases (folds of elbows, neck) or cheeks in children under 4 years5
- A skin biopsy is generally not helpful for diagnosis 3
Comorbidities
- AD is associated with other atopic conditions 4
- Asthma: Adults with AD are 3 times more likely to have asthma compared to the general population 4
- Food allergies: 11% of adults with AD have food allergies 4
- More severe AD appears to have a stronger association with asthma than mild or moderate AD 4
Management
- Emollients/moisturizers are essential for all patients with AD regardless of disease severity 1, 6
- Apply emollients immediately after a 10-15 minute lukewarm bath or shower for maximum benefit 6
- Avoid soaps and detergents as they remove natural lipids from the skin; use dispersible creams as soap substitutes 3
- Keep nails short and wear cotton clothing rather than irritating fabrics like wool to minimize damage from scratching 3, 6
- Avoid extremes of temperature 5
- Topical corticosteroids (TCS) are the first-line therapy for acute flares 1, 6
- Topical calcineurin inhibitors (TCIs) such as pimecrolimus 1% cream and tacrolimus ointment are steroid-sparing alternatives 6
- Proactive therapy approach: Twice-weekly application of low to medium potency TCS (e.g., fluticasone or mometasone) to previously affected skin areas for up to 16 weeks may help prevent relapses 2
- TCIs can also be used proactively to maintain remission 1
- Wet-wrap therapy with TCS is an effective short-term second-line treatment for moderate to very severe AD 6
- Phototherapy (narrowband UVB, broadband UVB, and UVA1) is recommended after failure of topical therapies 1
- Oral antihistamines may be used as adjuvant therapy for reducing pruritus 6
- Topical phosphodiesterase-4 inhibitors have been approved for mild to moderate AD 6
Treatment Cautions
- Long-term application of topical antibiotics is not recommended due to increased risk of resistance and skin sensitization 6
- Topical antihistamines are not recommended due to limited evidence and potential risk of contact dermatitis 6
Complications and Special Considerations
- Skin infections are common in AD patients 3, 5
- Bacterial infections, particularly with Staphylococcus aureus, are suggested by crusting or weeping 3
- Deterioration in previously stable eczema may be due to secondary bacterial infection, development of contact dermatitis, or viral infections (e.g., herpes simplex) 3, 5