Atopic Eczema Distribution: Flexural vs Extensor Surfaces
Atopic eczema (atopic dermatitis) predominantly affects flexural surfaces in older children and adults, but involves extensor surfaces and the face in infants and very young children—the distribution pattern is age-dependent. 1, 2, 3
Age-Specific Distribution Patterns
Infants and Very Young Children (< 4 years)
- Extensor surfaces of the limbs are characteristically involved, along with the cheeks, forehead, scalp, neck, and trunk. 2, 3, 4
- The diaper area is typically spared in infantile atopic dermatitis, which helps distinguish it from other conditions. 2, 3, 4
- Facial involvement (especially cheeks) is the hallmark presentation in this age group, distinguishing infant eczema from the flexural pattern seen in older children. 2, 5
- This extensor and facial distribution reflects the age-specific pattern in children around 1 year of age. 2
Older Children and Adults
- Flexural areas become the predominant sites, including the antecubital and popliteal fossae (folds of elbows and behind knees), along with the neck. 1, 3, 4
- The diagnostic criteria specifically reference "history of itchiness in skin creases such as folds of the elbows, around neck" and "visible flexural eczema" as key features in this population. 1
- Chronic rubbing of these flexural areas leads to lichenification (thickened skin with accentuated markings). 6
- Head and neck involvement persists across age groups but becomes associated with flexural rather than extensor disease. 3, 4
Clinical Reasoning for Age-Related Patterns
The shift from extensor to flexural involvement reflects the natural progression of atopic dermatitis:
- Infants have limited mobility and different friction patterns, leading to extensor surface involvement where skin contacts surfaces during crawling and movement. 2, 3
- Older children and adults develop flexural disease due to increased sweating, friction, and occlusion in skin folds, which perpetuates inflammation and scratching. 1, 6
Common Diagnostic Pitfalls
- Do not dismiss facial rashes in infants as simple "baby acne" without evaluating for atopic features—cheek involvement is typical for atopic dermatitis in this age group. 2
- Do not assume all flexural dermatitis is atopic without considering allergic contact dermatitis, which can mimic the flexural pattern; patch testing should be considered in chronic or recurrent cases. 7
- Recognize that rash in the diaper area of infants is rarely atopic dermatitis—this should prompt consideration of other diagnoses such as irritant contact dermatitis or candidal infection. 3, 4
Diagnostic Confirmation
When evaluating distribution, confirm the diagnosis using established criteria:
- Itchy skin condition (or observable scratching/rubbing in infants) plus three or more of: history of itchiness in skin creases (or cheeks in children < 4 years), personal or family history of atopy, general dry skin in the past year, visible flexural eczema (or cheek/forehead/extensor involvement in children < 4 years), and onset in the first two years of life. 1, 2