Atopic Dermatitis (Eczema)

Definition: Atopic dermatitis is a highly pruritic chronic inflammatory skin disease that commonly presents during early infancy and childhood but can persist or start in adulthood.

Minimum diagnostic criteria for atopic dermatitis according to Williams et al.1994 criteria 1994 validation 1994 hospital validation 1996 population validation.

Fulfilment of the major criterion plus three or more minor criteria leads to the diagnosis of atopic dermatitis.

Major criterion: An itchy skin condition (or parental report of scratching or rubbing in a child)

Minor criteria:

History of involvement of the skin creases such as folds of elbows, behind the knees, fronts of ankles or around the neck (including cheeks in children under 10 years)
A personal history of asthma or hay fever (or history of atopic disease in a first-degree relative in children under 4 years)
A history of a general dry skin in the last year
Visible flexural eczema (or eczema involving the cheeks/forehead and outer limbs in children under 4 years)
Onset under the age of 2 years (not used if child aged under 4 years)

At least two types of atopic dermatitis have been identified: an extrinsic type associated with IgE-mediated sensitisation, which affects 70–80% of patients; and an intrinsic type without IgE-mediated sensitisation, which affects 20–30% of patients.

Prevalence: Atopic dermatitis has a lifetime prevalence in children of 10–20% and a prevalence of 1–3% in adults. The prevalence seems to be increasing.

Trigger Factors after Hanifin and Tofte 1999 Atopic Dermatitis is a disease of inflammation of the skin.

Causes of Inflammation:
- Infections
- Allergy - both to food and aeroallergens.
Causes of Irritation of the inflamed skin

Bathing/moisturizing errors
Irritant exposure

Soaps, detergents
Disinfectants (e.g. chlorine)
Contact with (creating contact erythema)

Juices (usually acidic) from fresh fruits, meats, vegetables, etc.
Occupational chemicals, fumes, etc.

Heat/sweating/temperature/climate
Emotional stress
Hormone

The Role of Allergy

Allergy is an immune response that 20 - 30% of the population have and which creates inflammation by responding to certain common antigens (allergens).
In the first few years of life the response is to food allergens and later around age 2 - 3 years, the response is to aeroallergens (the allergic march).
Since atopic dermatitis commonly begins in infancy, and since 70 - 80% of patients with atopic dermatitis are allergic, the allergic response of infants with atopic dermatitis is usually to foods.
Six or seven foods are resonsible for the majority of allergic responses in North American infants including, milk, egg, peanut, nuts, fish, shellfish and seeds. A postive skin test does not automatically mean there will be a clinical reaction to a food (i.e., worsening of the eczema). Children with atopic dermatitis are often sensitized (i.e., have a positive skin test) to more foods than are creating problems with their eczema. There is no need for a broad restriction diet.
Nevertheless, the atopic immune response of infants with atopic dermatitis is often much greater than allergic infants with asthma.

Treatment

General Skin Care
Anti-inflammatory treatment for flares
Antimicrobial therapy

Skin Care: bathing/moisturizing: after Hanifin and Tofte 1999

Tub bath daily for 15 to 20 minutes using lukewarm water
For severe flaring or for very dry skin, tub bath twice daily for 20 minutes (until fingertips wrinkle), using lukewarm water only
Wet compresses if bathing is painful or for nighttime itch control
Shower, acceptable when skin is under good control or when flare is mild
Avoid washcloths, rubbing, scrubbing, or overuse of soap (use an oatmeal preparation)
After bathing, dry off only partially by patting with a towel; do not rub
While some water is still on the skin, within 3 minutes and before leaving the bathroom:
Apply steroid ointment to red, itchy areas
Apply moisturizer (not lotions) to other areas
Moisturizing should be repeated as often as necessary to keep skin soft throughout the day

Anti-inflammatory treatment for flares

For acute flares (red, itching, angry-looking skin), apply a topical mid-potency steroid as an ointment two or three times per day. For the face and other areas of thin skin, use a low potency topical steroid.
Alternatively for acute flares, the newer non-steroidal immunosuppressant agents, tacrolimus (Protopic) or pimecrolimus (Elidel) can be applied twice daily.
When the flare settles, discontinue the anti-inflammatory agents and continue with skin care.

Antimicrobial therapy

If the skin looks infected, (i.e. broken, inflamed and discharging), apply a topical antibiotic such as Fucidin or Bactroban, along with the topical steroid.
If the skin infection is wide-spread, an oral antibiotic may be necessary.

Ancillary Treatment
There are a number of other treatment modalities for difficult atopic dermatitis. Most are beyond the scope of this page but antihistamines are often tried for intractable itching. Generally the antihistamines have not been found to be very effective in blind-controlled studies. The itch of atopic dermatitis may not be due to histamine release and might be more like itching in poison ivy.

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