Atopic dermatitis (or atopic eczema) is a chronic, pruritic skin disorder affecting both adults and children. Evidence suggests it affects up to 20% of children and 3% of adults with prevalence varying greatly throughout the world. Whilst AD may affect patients of all ages, the peak age of onset is below 3 months. Both males and females are affected with studies showing a greater female propensity.
Atopic dermatitis is a common clinically hypersensitive state, subject to hereditary influences that manifests as a chronic inflammatory skin disorder beginning in early childhood. The aetiopathogenesis of atopic dermatitis is complex involving an interplay between genetic, immune, neuroendocrine and environmental factors. Studies have implicated mutations in the filaggrin gene on chromosome 1q21 in European and Japanese patients leading to a defective barrier function in the stratum corneum with resultant increased transepidermal penetration of environmental allergens, increased inflammation and sensitivity. Exacerbating factors for episodes of eczema include colonisation by microbial agents especially staphylococcus aureus, certain environmental exposures, disruption of the cutaneous barrier, exposure to allergies and stress.
Atopic dermatitis can be divided into acute, subacute and chronic stages. The acute stage is characterised by oedema, erythema, vesiculation, exudation and crusting. In subacute dermatitis there are erythematous, excoriated, scaling papules. The characteristic lesion of chronic AD is thickened plaques with lichenification. Lesions from all three stages may co-exist in the same patient. Dry, dull skin is seen in all stages of AD.
Atopic dermatitis shows distinctive morphology and distribution at various ages. In infancy, it usually involves the face and extremities. In childhood and adulthood, the flexural areas are the most common site. Chronic hand eczema is common in adults. However generalised involvement may also occur at any age.
Pruritis is the most common symptom experienced by patients and may be so severe that it leads to insomnia and secondary infection of open excoriations caused by scratching. Pruritis occurs throughout the day but is usually worst in the early evenings and at night.
Secondary bacterial and viral infection may lead to pruritis, pain and scarring.
The management of atopic dermatitis involves individualised care and is dependent on the age of the patient, severity of disease and patient affordability amongst other factors. The approach involves:
Since atopic dermatitis is a clinically hypersensitive state, various factors have been implicated in the exacerbation of the disease. Control of these aggravating factors significantly improves the signs and symptoms of the dermatitis.
Soap substitutes are advised in place of ordinary soap. Options include pure glycerine soaps or other moisturising cleansers. Anti-bacterial cleansers should be avoided as they may lead to bacterial resistance.
Treatment of any infections should be instituted as soon as they occur.
Since xerosis of the skin is a salient feature of AD, the judicious use of emollients is recommended as first-line therapy. These need to be applied frequently during the day to relieve symptoms and signs of dryness.
Antihistamines are often used for their effect on pruritis. However, because many mediators other than histamine are implicated in AD-induced pruritis, antihistamines may not be beneficial in all patients.
Topical Options: These include topical steroids and topical calcineurin inhibitors
Phototherapy: Both UVA and UVB either as monotherapy or as an adjunctive treatment has been shown to clinically improve AD.
Systemic Rx: Oral anti-inflammatory immunomodulators are reserved for patients with severe atopic dermatitis or recurrent or recalcitrant disease. These include azathiaprine, methotrexate, cylcosporin and biologics. Management is individualised per patient.
Recent advances have revolutionised the understanding of atopic dermatitis, especially at the molecular and genetic levels. This provides avenues to translate research into the formulation of new and better treatments. In the interim, however, patients still experience a wide range of symptoms affecting their lives and the lives of their families. These symptoms range from trivial to disabling. Some of them can be measured clinically but others occur at a more subtle psychological level. Understanding the exact impact of the disorder is imperative in the management of these patients.