Burden in hot weather------Eczema & Dermatitis ___ features##treatment ##Atopic Dermatitis

 Eczema & Dermatitis

The terms ‘eczema’ and ‘dermatitis’ are synonymous.

Epidemiology

■ It is estimated that 10% of people have some form of eczema at any one time

■ Up to 40% of the population will have an episode of eczema during their lifetime.

Etiology

There are several patterns of eczema-

Endogenous

      • Atopic

      • seborrhoeic

Exogenous

      • Irritant

      • Allergic

      • Photoallergic

➣There are strong familial associations with a strong maternal influence in atopic diseases.

➣The role of house dust mites and diet is less clear cut

➣Food (Eggs, cow’s milk, protein, fish, wheat and soya ) in atopic disease

>Infection: either in the skin or systemically can lead to an exacerbatio

(possibly by a superantigen effect)

➣Paradoxically, lack of infection (in infancy) may cause the immune system to follow a Th2 pathway and allow eczema to develop (the so-called ‘hygiene hypothesis’)

➣Severe anxiety or stress appears to exacerbate eczema in some individuals

Common irritants in Irritant eczema

➣Detergent

➣Alkalis & acid

➣solvents and abrasive

Pathophysiolog

■ The exact pathophysiology is not fully understood but

■ there is an initial selective activation of Th2-type CD4 lymphocytes in the skin which drives the inflammatory process.

■ This precedes the chronic phase when Th0 and Th1 cells predominate.

■ In at least 80% of cases there is a raised serum total IgE level.

Clinical Presentation

■ The clinical features are similar, irrespective of the cause.

■ Vesicles or bullae may appear in the acute stage if inflammation is intense.

■ In subacute eczema the skin can be erythematous, dry and flaky, oedematous and crusted (especially if secondarily infected).

■ Chronic persistent eczema is characterized by thickened or lichenified skin.

Specific Types of Eczema are described below-

Atopic eczema

• Generalised, prolonged hypersensitivity to common environmental antigens (such as Pollen house dust mite) in which there is a genetic predisposition to produce excess IgE.

• It is commoner in early life, occurring at some stage during childhood in up to 10–20% of all children.

• Atopic individuals manifest one or more of a group of diseases that includes-

• asthma,

• hay fever,

• food and other allergies

Symptoms in Atopic Eczema

■ Atopic eczema is extremely itchy.)

■ Widespread cutaneous dryness

 (roughness) is another feature

■ Common sites-

• Children-

 Flexures: behind knees, antecubital fossae, wrists and ankles.

• Adults- 

Face and trunk usually involved, limb involvement not restricted to flexures

Irritant eczema 

➣Strong irritants have acute effects whereas

➣weaker irritants commonly cause chronic eczema, especially of the hands, after prolonged exposure.

Allergic contact eczema

This occurs due to a delayed hypersensitivity reaction following contact with antigens.

Common allergens are listed-

■ Nickel (Jewellery, bra clips,Watches)

■ Dichromate 

(Cement, leather)

■ Rubber chemicals (Clothing, shoes, rubber gloves, tyres )

■ Perfumes, shower/bath products

■ Neomycin, benzocaine

 (Topical medications)

■ Preservative in cosmetics and creams

■ Resin adhesives, glues.

Investigations

The diagnosis of atopic eczema is clinical.

■ serum IgE levels or high specific IgE levels

- #( not routinely donein atopic eczema)

■ Serum eosinophil count

- # in about 80% of cases

•Skin prick test for allergic status

Skin prick test for allergic status

 is not usually helpful.

■ Skin scrapings

-to rule out secondary fungal infection should be considered.

■ Skin  Biopsy

- is not usually required unless there is diagnostic doubt.eg. of a drug reaction or cutaneous lymphoma

Management

General management

1. Avoiding known irritants (especially soaps or furry animals)

2. Wearing cotton clothes

3. Not getting too hot.

4. Manipulating the diet (e.g. dairy-free diet) is rarely beneficial except in a few children, especially those under 12 months of age where cows milk and egg allergy are common

5. Bath oils/soap substitute (e.g. aqueous cream) helps.

6. Regular use of emollients (e.g. 

emulsifying ointment)- mainstay treatment.

Caution

 - non-sedating antihistamines are ineffective

Drug Treatment

1. Sedative antihistamines (eg. 

Chlorpheniramine Maleate )- useful if sleep is interrupted

Hydroxyzine Hydrochloride

oral 

 (10–25 mg) are useful at night-time.

2..Topical corticosteroids

Ointments are preferred for chronic eczema,

• cream or lotion-based treatment may be more appropriate for acute eczema

Tacrolimus 0.1%, 0.03% Topical

 (0.1% and 0.03%) and the less potent

Pimecrolimus 1% Topical

Immunomodulators-

 can be used for atopic eczema in patients over 2 years old.

Advantage-

• over potent steroids of not causing skin atrophy

• The milder potency steroid creams are still first-line therapy

but tacrolimus is a useful alternative to excessive use of potent steroids.

but tacrolimus is a useful alternative to excessive use of potent steroids.

• Thus very useful for treating sensitive areas such as the face and eyelids.

Caution:

■ They can be irritant when first used (although this settles with continued use).

■ They do not work so well on lichenified eczema, probably due to poor absorption.

■ Current advice is to avoid vaccinations and sun exposure when using these agents.

3..Adjunct therapies:

a. oral antibiotics-

 needed for bacterial infection and are usually given orally for 7–10 days.

         Flucloxacillin

        (500 mg four times daily) is effective              against gram positive organism

       Phenoxymethyl Penicillin

      (500 mg four times daily) acts against 

       Streptococcus

.

       Erythromycin

       (500 mg four times daily) is useful if               there is allergy to penicillin.

b. Bandaging-

 can be useful for resistant or lichenified eczema of the limbs. 

3. Phototherapy

4. Systemic therapy

, e.g. oral prednisolone, ciclosporin-used in severe non-responsive cases

Guidelines for safe use of tropical steroid

The following should be followed in common chronic inflammatory skin conditions-

➣The face-should be treated only with mild steroids.

➣The body-

■ In adults- with either mild, moderately potent or diluted potent steroids.

■ In young children- only mild and moderately potent steroids.

➣Potent steroids are used for short courses (7–10 days).

➣Palms and soles (but not the dorsal surfaces) may require potent or very potent steroids

(as the skin is much thicker).

➣Regular use of emollients may lessen the need for steroid use. 

➣Only use steroids on inflamed skin. Do not use as an emollient.

➣Use weaker steroid preparations in flexures (e.g. the groin, and under breasts)

(as apposition of the skin at these sites tends to occlude the treatment and increase absorption.)

Prognosis

■ The majority (80–90%) of children with early-onset atopic eczema will spontaneously improve and ‘clear’ before the teenage years, 50% being clear by the age of 6.

■ A few will get a recurrence as adults, even if just as hand eczema.

■ However, if the onset of eczema is late in childhood or in adulthood, the disorder follows a more chronic remitting/ relapsing course.