Allergy: Eczema Flashcards
What percentage of children with atopic dermatitis develop asthma or allergic rhinitis later in life?
Up to 80%
What is the prevalence of atopic dermatitis in children in the UK?
Approximately 20%
Do many affected children have a FH of allergy?
Yes
Are IgE antibodies to common allergens usually present?
Yes
What gene mutations have been identified as the key genetic risk factor for eczema development?
Filaggrin mutation - impairment of skin barrier function. This leads to cutaneous sensitisation to inhalant and food allergens
(Filaggrin mutation predisposes to food allergy, asthma, hay fever as well as eczema)
What percentage of young infants with severe eczema have an IgE mediated food allergy?
40% - in particular egg allergy
When does the onset of atopic eczema generally occur?
First year of life
Uncommon in first 2 months (unlike infantile seborrhoeic dermatitis)
What are atopic disorders?
Atopic dermatitis
Asthma
Allergic rhinitis (hay fever)
What percentage resolves by 12 years of age?
50% and 75% by 16
What may delay the onset of atopic dermatitis in predisposed children?
Exclusive breastfeeding
How is it diagnosed?
Clinically
If unusually severe, atypical, associated with unusual infections or faltering growth - an immune deficiency disorder should be excluded
What is the main symptom at all ages?
Pruritus
What does the distribution of atopic eczema change with?
Age
Which areas of the body are typically affected in infants?
Face
Scalp
Trunk
Which areas of the body are typically affected in older children?
Skin flexures - cubital and popliteal fossae
Frictional areas - neck, wrists, ankles
Describe the appearance
Itchy, dry patches of papules and vesicles on an erythematous base.
Scratching can lead to…
Excoriation areas
Prolonged scratching and rubbing of the skin can lead to..
Lichenification
Are flare ups common?
Yes and often for no obvious reason
Describe mild atopic dermatitis
Areas of dry skin
Infrequent itching
With/without small areas of redness
Little impact on everyday activities, sleep, psychosocial well-being
Describe moderate disease
Areas of dry skin
Frequent itching
Erythematous areas
With or without excoriation and localised skin thickening
Moderate impact on everyday activities, frequently disturbed sleep
Describe severe disease
Widespread areas of dry skin
Incessant itching
Erythema
With or without excoriation, extensive thickening, bleeding, oozing, cracking and alteration of pigmentation
Severe limitation of everyday activities and psychosocial functioning, nightly sleep loss
What complications can occur?
Bacterial infection - staphylococcus and streptococcus species Viral infections - herpes simplex Ingestion of an allergen e.g egg Contact with an irritant or allergen Environment: heat, humidity Change or reduction in medication Psychological stress
What bacteria thrives on atopic skin?
Staphylococcus aureus
Why is an herpes simplex infection potentially very serious?
Can spread rapidly on atopic skin
Extensive vesicular reaction
= eczema herpeticum
What is common on examination in active eczema?
Regional lymphadenopathy
In terms of management, what options are available?
Avoiding irritants and precipitate Emollients Topical corticosteroids- mild and moderate Immunomodulators Occlusive bandages Antibiotics, antivirals, antihistamines Dietary elimination Phototherapy Systemic therapy Psychosocial support
What irritants and precipitants should be avoided?
Soap
Biological detergents
Clothing next to skin should be of pure cotton (avoid nylon and pure woollen garments)
Cut nails
Mittens at night
Avoid allergen if one has been identified e.g cow’s milk
What is the mainstay of management?
Emollients - moisturise and soften skin
How should emollients be applied?
Liberally
2 or more times per day
After a bath
They include ointments - preferable to creams when skin very dry
What is an example of a mildly potent corticosteroid?
1% hydrocortisone- applied for eczematous area once/twice per day
Moderately potent corticosteroids play a role in the management of…
Acute exacerbations
Should be kept to a minimum
Moderately potent topical corticosteroids should be avoided on…
The face
What can be used in children over 2 if eczema NOT controlled by topical corticosteroids or serious risk of adverse effects from further topical steroids (e.g irreversible skin atrophy)?
Short term use of tacrolimus ointment or pimecrolimus cream (immunomodulators)
What is the role of occlusive bandages?
Helpful over limbs when scratching and lichenification are a problem.
May be impregnated with zinc paste or zinc and tar paste
Worn overnight for 2-3 days at a time until skin improved
Widespread itching in young children: short term use of wet stockinette wraps - dilute topical steroids mixed with emollient
What can be used for itch suppression?
Antihistamines but should not be used routinely in children
Offer 1 month trial if moderate to severe itching
OR 7-14 day trial to children over 6 months if acute flare if sleep disturbed
Non sedating e.g cetirazine
How should mild atopic eczema be managed?
Emollients
Mild potency topical corticosteroids
How should moderate atopic eczema be managed?
Emollients
Moderate potency topical corticosteroids
Topical calcineurin inhibitors e.g tacrolimus
Bandages
How should severe atopic eczema be managed?
Emollients Potent topical corticosteroids Topical calcineurin inhibitors Bandages Phototherapy Systemic therapy
What antibiotic should be used in first line treatment for widespread bacterial infection ?
Flucloxacillin for 1 to 2 weeks according to clinical response
When should food allergy be considered?
Child reacts consistently to food
In infants and young children with moderate or severe atopic eczema, particularly if associated with gut dysmotility or faltering growth
If eczema herpeticum is suspected, how should the child be managed?
Oral aciclovir started immediately even if localised infection
