Atopic Dermatitis Onset in Infants

Epidemiology of Onset

Approximately 60% of patients develop skin eruption in the first year of life, according to the American Academy of Dermatology 1
About 90% of cases manifest before the age of 5, as reported by the American Academy of Dermatology 1
Onset before 3 months is possible but represents a minority of cases, as noted by the American Academy of Dermatology 1

Typical distribution: lesions typically start on the cheeks and extend over time to the neck, trunk, and extensor surfaces of the limbs, as described by the Journal of Microbiology, Immunology and Infection 3, 4
Characteristic sparing: the diaper area is typically spared, as reported by the Journal of Microbiology, Immunology and Infection 3, 4

Distinguishing atopic dermatitis from seborrheic dermatitis can be challenging in the first few months of life, and the two conditions can overlap, according to the American Academy of Dermatology 5
Key differences: atopic dermatitis typically spares the inguinal and axillary regions, while seborrheic dermatitis affects these areas and tends not to be pruritic, as noted by the American Academy of Dermatology 5

Duration of symptoms: in infants, a duration of >2 months is required (compared to >6 months for older children and adolescents), as reported by the Journal of Microbiology, Immunology and Infection 3, 4
Distribution pattern: lesions in infants follow a specific pattern with involvement of cheeks, extensor surfaces, and sparing of the diaper area, as described by the Journal of Microbiology, Immunology and Infection 3, 4

If an infant under 3 months presents with eczematous lesions that do not respond to therapy, it is essential to consider more severe nutritional and metabolic conditions, as well as immunodeficiency states, according to the American Academy of Dermatology 5
Scabies: check for burrows in interdigital spaces, as reported by the BMJ 6
Infants at high risk for developing early atopic dermatitis include those with a family history of allergic rhinitis, asthma, atopic dermatitis, or food allergy, as noted by the American Academy of Pediatrics 7