Atopic Dermatitis: a Review of Recent Advances in the Field

Authors and Disclosures

Joseph Lam,¹ and Sheila F. Friedlander <sup>2

1</sup>Department of Pediatrics, University of British Columbia, School of Medicine, British Columbia, Vancouver, Canada
²Departments of Pediatrics & Medicine (Dermatology), University of California, San Diego School of Medicine, CA

Conclusion & Future Perspective (5-10 Years)

Essential Features

• Pruritus

• Eczematous changes

  • Typical and age-specific patterns: face, neck and extensor involvement in infants and children; flexural lesions, especially in older children and adolescents; and sparing of the groin and axillae

  • Chronic or relapsing course

Important Features (Observed in Most Cases and Add Support to the Diagnosis)

• Early age of onset

• Atopy (IgE reactivity)

• Xerosis

Associated Features (Too Nonspecific to Define Atopic Dermatitis)

• Keratosis pilaris/ichthyosis/palmar hyperlinearity

• Atypical vascular responses

• Perifollicular changes

• Ocular/periorbital changes

• Perioral/periauricular lesions

Exclusions

• The diagnosis of atopic dermatitis depends upon the exclusion of conditions such as scabies, allergic contact dermatitis, seborrheic dermatitis, psoriasis, ichthyosis and other primary disease entities.

Sidebar: The UK Working Party's Diagnostic Criteria for Atopic Eczema

Must have an itchy skin condition (or parental report of scratching or rubbing in a child; screening question), plus three or more of the following:

• History of involvement of the skin creases, such as folds of elbows, behind the knees, front of ankles or around the neck (including cheeks in children under 10 years of age).

• A personal history of asthma or hay fever (or history of atopic disease in the first degree relative in those under 4 years).

• A history of a generally dry skin in the last year.

• Visible flexural dermatitis (or dermatitis involving the cheeks/forehead and outer of the limbs in children under the age of 4 years).

• Onset under the age of 2 years (not used in children below the age of 4 years).

Data taken from reference 54.

Sidebar: Executive Summary

Epidemiology

• The incidence of atopic dermatitis has increased two- to threefold in industrialized areas within the last three decades.

• 60% of affected children present within the first year of life.

• Although many children improve with age, at least 17% will have intermittent symptoms at the age of 7 years.

Pathogenesis

• Genetic factors play an important role in disease; there is a 75% concordance rate in monozygotic twins and risk increases with a history of parental disease.

• Several associated genetic loci have been identified, including 5q31-33. Genes in these loci control cytokine production, which impacts on IgE synthesis, supporting the belief that immune dysregulation plays a key role in pathogenesis.

• Loss-of-function mutations in filaggrin, a key epidermal structure component, have been associated with patients with atopic disease, supporting the role of impaired barrier function in atopic dermatitis.

• Cathelicidins, important peptides that provide innate immunity, are decreased in patients with atopic dermatitis, probably contributing to the increased incidence of both staphylococcal and herpetic infections observed in atopics.

Clinical Findings

• Three morphologic forms of atopic dermatitis exist: infantile, childhood and adult.

• All are associated with pruritus and a relapsing remitting course.

• Acute lesions are papular, papulovesicular and plaque-like; excoriations and oozing are common secondary findings.

• Chronic lesions exhibit lichenification.

Prevention

• Exclusive breastfeeding in the first 4 months of life may be protective.

• Withholding solid foods for longer than 6 months has not been shown to be helpful.

• Soy formula does not prevent the development of atopic disease.

• Hydrolyzed-based formulas may provide some protection, but cost much more than cow-based formulas; amino acid-based formulas may help allergic children but have not been studied for use in preventing disease.

Therapy

• Appropriate preventive skin care is the mainstay of therapy; patients must hydrate and protect their skin as well as avoid irritants.

• Topical corticosteroids are very helpful for mild-moderate disease; the weakest potency that is effective should be used, but moderate steroids may sometimes be required for control. These agents should be used on an intermittent basis, as side effects can occur with excessive and prolonged use. Conversely, steroid phobia must be avoided, and families should be reassured regarding the safety of appropriately utilized therapy.

• Topical calcineurin inhibitors are useful agents, particularly for chronic and facial disease. Families must be counseled regarding their associated black box warnings.

• Antihistamines serve mainly as soporifics in patients with atopic dermatitis, but can be useful to increase night-time sleeping.

• Secondary infections, particularly with Staphlococcus auerus or herpes simplex virus, can complicate the course of disease and should be treated appropriately.

• Narrow-band UVB therapy can be efficacious and appropriate for significant disease.

• A variety of systemic agents are available for severe disease, and include cyclosporine, azothiprine and rituximab. They all carry more significant adverse effect concerns, and patients must be monitored accordingly.