Overview
Also known as atopic dermatitis, atopic eczema is a chronic inflammatory skin condition that most frequently presents in early childhood, usually before 5 years of age, characterised by dry, itchy skin that tends to occur in flares and remissions.
Inflammation of the skin can lead to an impaired skin barrier, risking secondary infection, which can be due to Staphylococcus aureus or herpes simplex virus (eczema herpeticum).
Atopic eczema is an IgE-mediated (type I) hypersensitivity reaction.
Epidemiology
- Around 70-90% of cases can occur before 6 years of age
- Around 65% of cases can occur in the first year of life
- Around 30% of people first develop symptoms as adults
Risk Factors
There is no known single cause, however, the following risk factors increase its likelihood:
- Family history of atopy – around 70% of people have a family history of atopic disease and there is strong evidence of a genetic component
- Personal history of atopy
- A loss-of-function Filaggrin gene mutation – responsible for maintaining the skin barrier
- Certain triggers:
- Soap and detergents
- Pollen, house dust mites, animal dander
- Rough clothing, certain foods
- Stress, extreme temperatures
Presentation
Overview
The general features of rash in atopic eczema are:
- Itching – the diagnosis is unlikely to be atopic eczema if there is no itch
- Dry skin that may appear greyish (or ashy) in people with darker skin tones
- Erythema
- Affected areas are not usually well-defined
- Excoriations – seen in areas that are easy to reach and itch
- Papules, pustules, and vesicles – more common in acute flares
- Lichenification – thickening of the skin where atopic eczema has been present for a long time
The distribution of the rash varies according to age and chronicity:
- In infants:
- The face, scalp, trunk, and extensor surfaces of the limbs tend to be affected
- The nappy area is usually spared
- In children and adults with long-standing disease:
- The flexors of the limbs and skin creases of the face and neck are usually affected
- Acute eczema (flares):
- Erythema, vesicles, scaling, crusting, papules, and pustules may be present
- Chronic eczema:
- Lichenification and keratosis pilaris may be present
Secondary infection
Features of infection may be present. This may present as worsening eczema and/or the emergence of new features:
- Bacterial infection, particularly Staphylococcus aureus – features similar to impetigo are seen:
- Crusting – usually yellow
- Weeping – oozing liquid, which may be pale yellow
- Pustules
- Surrounding cellulitis
- Herpes simplex infection – eczema herpeticum, a dermatological emergency:
- A rapidly-progressing painful rash
- Grouped vesicles and punched-out circular ulcerated lesions are seen
- Fever, lymphadenopathy, and malaise may be seen
Diagnosis
Overview
The diagnosis of atopic eczema is clinical provided no other alternative differential diagnoses are suspected.
Differential Diagnoses
Psoriasis
- The rash tends to be less itchy
- The rash appears as well-circumscribed plaques with silvery scales
- Nail pitting may be seen
- The rash tends to be found on the extensor surfaces of the knees and elbows
Allergic contact dermatitis
- Eczematous rashes tend to be localised to a specific area after exposure to a certain allergen
- Signs and symptoms tend to occur 24-72 hours after exposure due to allergic contact dermatitis being a delayed-type hypersensitivity reaction
Seborrhoeic dermatitis
- Well-demarcated erythematous lesions with greasy scale
- Often found on the cheeks, scalp (‘cradle cap)’, extremities, and trunk
Scabies
- Severe, acute itching
- Burrows may be seen
- Household members or close contacts may also be affected
Food allergy
- May be present in children and young people who have not responded to typical therapy for atopic eczema
Management
Non-infected atopic eczema
In general:
- Avoid potential triggers
- 1st-line: prescribe a generous amount of emollients for both acute flares and remissions
- If the skin is inflamed, consider a topical corticosteroid for the shortest amount of time possible.
- Treatment should be continued for more than 48 hours after the flare has stopped.
- For eczema that does not affect the face, genitals, or axillae, consider a mildly potent, moderately potent, or potent topical corticosteroid depending on eczema severity
- For eczema that affects the face, genitals, or axillae, consider a mild potency topical corticosteroid and increase to moderate potency only if necessary
- In general, treatment should be stepped down to the lowest potency and should be intermittent
Other options under specialist advice include:
- Occlusive dressings or dry bandages
- In severe, refractory eczema, oral ciclosporin may be considered
Infected atopic eczema
If a secondary bacterial infection is suspected, antibiotic treatment may be given if patients are systemically unwell, have severe signs or symptoms, are immunocompromised, or are at high risk of complications.
- Flucloxacillin is first-line (or clarithromycin if penicillin-allergic)
If eczema herpeticum is suspected, arrange immediate hospital admission.
Referral
Arrange immediate hospital admission if eczema herpeticum is suspected as this can be life-threatening.
Refer to a dermatologist if any of the following apply:
- Diagnostic uncertainty
- Eczema is not controlled with treatment in primary care
- Recurrent secondary infections
- High risk of complications
- Treatment advice is needed (e.g. bandaging techniques)
Refer to an immunologist, paediatrician, or dermatologist if a food allergy is suspected.
Complications
- Secondary bacterial infection (usually Staphylococcus aureus)
- Herpes simplex infection – eczema herpeticum
- Psychosocial problems (e.g. problems with self-esteem, bullying, time away from school etc.)
- Development of another atopic condition
Prognosis
- Atopic eczema clears in around 74% of children by 16 years of age
- Most cases are mild and <10% of patients have severe eczematous skin lesions
- Up to 50% of children with atopic eczema will go on to develop asthma and up to 80% may develop hayfever. This sequence of events is known as the ‘atopic march’.
