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SOURCE

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Source: Law RM, Kwa PG. Atopic dermatitis. In: DiPiro JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey LM, eds. Pharmacotherapy: A Pathophysiologic Approach. 10th ed. New York, NY: McGraw-Hill; 2017. http://accesspharmacy.mhmedical.com/content.aspx?bookid=1861&sectionid=146070205. Accessed May 9, 2017.

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CONDITION/DISORDER SYNONYM

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  • Eczema.

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DEFINITION

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  • Chronic, inflammatory skin eruption associated with red patches and intense itching; usually begins in infancy and may continue into adult life.

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ETIOLOGY

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  • Genetic, environmental, and immunologic mechanisms.

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EPIDEMIOLOGY

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  • Affects 15–30% of children and 2–10% of adults in developed countries.

  • Prevalence has increased two- to threefold over past 3 decades.

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RISK FACTORS

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  • Family history of atopic diseases.

  • A loss of function mutations in the FLG gene.

    • Predisposing factors.

    • Climate—hot and extremely cold climates.

    • Infection—Patients with AD are commonly colonized by Staphylococcus aureus bacteria. Clinical infections with S. aureus frequently cause are ups of AD.

    • Genetics.

    • Environmental aeroallergens (eg, dust mites, pollens, molds, cigarette smoke, and dander from animal hair or skin)

    • Food.

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PATHOPHYSIOLOGY

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  • Neuropeptides, irritation, or scratching causes release of proinflammatory cytokines from keratinocytes.

  • Alternatively, allergens in epidermal barrier or in food may cause T-cell mediated but IgE-independent reactions.

  • Characteristic features in pathophysiology are skin barrier dysfunction, and immune deviation toward TH2 with subsequent increased IgE.

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CLINICAL PRESENTATION

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SIGNS AND SYMPTOMS
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  • Presentation depends on age.

  • In infancy, erythematous, patchy, pruritic, papular skin rash may first appear on cheeks and chin and progress to red, scaling, oozing lesions. Affects malar region of the cheeks, forehead, scalp, chin, and behind ears while sparing nose and paranasal creases. Lesions spread over several weeks to extensor surfaces of the lower legs (due to crawling); may involve entire body except diaper area and nose.

  • In childhood, skin often appears dry, flaky, rough, and cracked; scratching may cause bleeding and lichenification.

  • In adults, lesions are more diffuse with underlying erythema. The face is commonly involved; may be dry and scaly. Lichenification may be seen.

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DIAGNOSIS

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MEANS OF CONFIRMATION AND DIAGNOSIS
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  • Based primarily on patient history, signs, and symptoms.

    • Essential features (must be present):

      • Pruritis.

      • Eczema (acute, subacute, chronic)

        • Typical morphology and age-specific patterns.

          • Facial, neck, external involvement (infants, children)

          • Flexural lesions (any age group)

          • Sparing of groin and axillary regions.

        • Chronic or relapsing history.

    • Important features (seen in most cases, supports the diagnosis of AD):

      • Early age of onset.

      • Atopy.

        • Personal/family history.

        • IgE reactivity.

      • Xerosis.

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LABORATORY TESTS
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  • Allergy skin testing may help identify factors that trigger flares.

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DIFFERENTIAL DIAGNOSIS
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DESIRED OUTCOMES

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  • Provide ...

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