What are the characteristics and treatment options for atopic dermatitis rash?

Atopic Dermatitis Rash Description

Atopic dermatitis presents as intensely pruritic eczematous lesions with age-specific distribution patterns: in infants, erythematous papules with exudation typically start on the cheeks and extend to the neck, trunk, and extensor surfaces (sparing the diaper area); in older children and adults, chronic lichenified plaques predominantly affect flexural areas including the antecubital and popliteal fossae. 1

Clinical Morphology by Disease Stage

The rash appearance varies significantly based on acuity and chronicity:

Acute Lesions

• Erythematous papules and vesiculopapules with serous exudation 1, 2
• Weeping and crusting when bacterial superinfection is present 1
• Secondary excoriations and crusted erosions from scratching 2

Subacute Lesions

• Erythematous scaling papules and plaques 2
• Less exudation than acute phase 2

Chronic Lesions

• Lichenification with accentuated skin markings 1
• Prurigo nodules 1
• Scales and crusts 1
• Hyperpigmentation from chronic inflammation 2

Age-Specific Distribution Patterns

Infancy (Under 4 Years)

• Cheeks and forehead are primary sites 1
• Extension to neck, trunk, and extensor surfaces of extremities over time 1
• Notable sparing of the diaper area (rash in this location is rarely atopic dermatitis) 1, 2

Childhood and Adolescence

• More localized and chronic presentation 1
• Flexural surfaces are predominantly affected: antecubital fossae, popliteal fossae 1, 2
• Head and neck involvement common 2

Adults

• Similar flexural distribution as older children 2
• Often more lichenified and chronic in appearance 2

Essential Diagnostic Features

All three criteria must be present for diagnosis: 1

1. Pruritus with symmetrical distribution (or report of scratching/rubbing in children) 1
2. Eczematous lesions with age-appropriate distribution 1
3. Chronic or relapsing course: >2 months in infancy, >6 months in childhood/adolescence 1

Associated Skin Findings

General Characteristics

• Generalized dry skin (xerosis) in the past year 1, 3
• Intense pruritus that triggers the itch-scratch cycle 1, 3
• Often coexisting new and old lesions simultaneously 1

Signs of Complications

Bacterial infection (most commonly Staphylococcus aureus):

• Crusting and weeping beyond typical presentation 1
• Golden-yellow crusts 1
• Bacteriological swabs indicated if no response to treatment 1

Herpes simplex infection (eczema herpeticum):

• Grouped, punched-out erosions 1
• Multiple discrete vesicles 1
• Less commonly, vesiculation 1
• Requires immediate virological screening and electron microscopy 1
• Can be life-threatening 2

Severity Grading

Mild: Only mild erythema, dry skin, or desquamation regardless of body surface area 1

Moderate: Severe eruptions (erythema, papules, erosion, infiltration, or lichenification) in <10% of body surface area 1

Severe: Severe eruptions in 10-29% of body surface area 1

Very Severe: Severe eruptions in ≥30% of body surface area 1

Key Clinical Pitfalls

Do not diagnose atopic dermatitis if:

• Rash is present in the diaper area in infants (this location is rarely atopic dermatitis) 1, 2
• Pruritus is absent (scratching or rubbing must be reported) 1
• Distribution is asymmetric 1

Consider alternative diagnoses including other skin disorders, infectious diseases, primary immunodeficiencies, nutritional deficiencies, or skin malignancies that may mimic atopic dermatitis 1

Deterioration in previously stable disease suggests secondary bacterial or viral infection, or development of contact dermatitis 1