A 6-month-old girl is brought to the office due to a rash on her cheeks, arms, and chest for the past 2 weeks. She is constantly scratching and rubbing her arms, and her parents are having a hard time keeping her hands away from the affected areas. The patient drinks breast milk and formula and has not started solid foods. There are no household pets, and she is bathed every 2 days with a body wash free of fragrance, alcohol, and dyes. The patient has not been exposed to new clothing, detergents, lotions, or other substances. Physical examination of the arms is shown in the exhibit. The face and chest have similar lesions. There is no rash in the diaper area or on the palms or soles. Which of the following is the most likely diagnosis in this patient?
Atopic dermatitis (eczema) | |
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This infant has dry, pruritic, erythematous patches on the face, trunk, and extremities, findings characteristic of atopic dermatitis (eczema).
This common condition typically begins in infancy/early childhood and is due primarily to genetically mediated skin barrier dysfunction. Dysfunction leads to loss of epidermal water content, increased permeability to environmental irritants/allergens, and skin inflammation. Exacerbating factors include low humidity, stress, overheating, and irritant/allergen exposure; however, flares can also occur in the absence of these exogenous factors.
The diagnosis of atopic dermatitis is clinical based on findings of dry skin, intense pruritus, and characteristic morphology and distribution.
Infants typically have lesions on the face, trunk, and extensor surfaces of the extremities; the diaper area is classically spared. In contrast, older children and adults tend to have lesions in the flexural creases.
(Choice A) Although allergic contact dermatitis can present with pruritic erythematous patches, the affected area is isolated to regions exposed to allergens and is rarely widespread. Furthermore, the use of hypoallergenic toiletries in this patient with no recent change in products makes this diagnosis less likely.
(Choice C) Eczema herpeticum, a potentially life-threatening complication of atopic dermatitis, is caused by herpes simplex virus superinfection. Patients typically have fever, irritability, and painful vesicles, none of which are seen in this patient.
(Choice D) Plaque psoriasis is characterized by sharply demarcated, not ill-defined, erythematous plaques with prominent silvery scales, findings not present in this patient.
(Choice E) Seborrheic dermatitis, a common condition in infants, is characterized by greasy, yellow scales on the scalp and erythematous plaques on characteristic areas (eg, diaper region). The extremities and chest are typically spared, and pruritus is uncommon, making this diagnosis unlikely.
Educational objective:
Atopic dermatitis classically presents with dry, pruritic, erythematous patches due to skin barrier dysfunction. In contrast to flexor surface distribution in older children and adults, affected areas in infants include the face, chest, and extensor surfaces of the extremities.