Chapter 86

• In infant atopy, cheeks and extensor surfaces of the legs are most commonly affected. Later in childhood, the antecubital and popliteal fossae are effected.
• Sudden onset of severe itching with similar complaints from other family members should raise your suspicion of scabies even if burrows are not visible.
• Urticaria tend to disappear and reappear over different areas of the body; whereas, erythema multiforme are fixed lesions. Subcutaneous epinephrine clears urticaria; however, it does not affect erythema multiforme.
• Stevens–Johnson syndrome and toxic epidermal necrolysis differ from erythema multiforme in that there is mucosal involvement and systemic symptoms are present. All three entities can be caused by a variety of drugs and infections.

### Etiology

Atopic dermatitis affects approximately 15% of children in the United States and accounts for up to 4% of all emergency department visits.1 The causal basis of atopic dermatitis is uncertain. It is evident however, that patients with a personal history and/or a family history of asthma and other allergies are more prone to atopic dermatitis.2 Patients with a genetic predisposition have a 90% chance of developing atopic dermatitis by the age of 5 years and a 95% chance by the age of 15 years.3

### Pathophysiology

Atopic dermatitis, also known as eczema, is thought to result from chronic inflammation of the skin. The exact mechanism is unknown; however, it is known that the skin barrier (stratum corneum) functions are defective. One hypothesis that exists is that there are genetic, environmental, pharmacologic, and immunologic triggers that induce hypersensitivity of the skin.1,3 It generally presents in infancy. The course of the disease is unpredictable, but the symptoms in most children will resolve before adulthood.

### Recognition

Diagnosis can be made by the presence of pruritis, typical morphology and distribution of the rash, and a strong family history of atopy. The rash usually presents after 4 to 6 weeks of life, where it characteristically involves the cheeks, trunk, and extensor surfaces (Fig. 86–1). Infants usually present with exudative lesions. In children, the distribution is over the flexor surfaces, including the antecubital and popliteal fossae. They present with areas of hypopigmentation and diffuse scaly patches. By adolescence, the involvement is the same with the addition of the face, neck, hands, and feet. Lichenification and hyperpigmentation are findings characteristic of chronicity. The clinical course of atopic dermatitis is characterized by relapsing episodes of symptom flares.

###### Figure 86-1.

Atopic dermatitis seen over the trunk of an infant.

### Management

Since there is no definitive treatment, education, reduction of symptoms, and prevention are the key. Avoidance of nonspecific skin irritants such as synthetic fabrics, wool, and nonessential, highly fragranced toiletries is the first step. Keeping the skin moisturized as much as possible helps ...

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