Eczema Flashcards
What aspects of the skin does eczema affect?
•Commonly affects flexural areas.
To what demographic does eczema most commonly appear?
Most commonly appears in babies and children - by adult life 60% have cleared
What is the definition of atopic eczema?
An itchy skin condition in the last 12 months
Plus 3 of the following:
- Onset before age age of 2
- History of flexural involvement
- History of generally dry skin
- History of other atopic disease (asthma / hayfever)
- History in 1st degree relative if under 4 years
What gene is associated with eczema?
Filaggrin gene
Atopic family history is also associated - atopic eczema, asthma, hay fever (allergic rhinitis), food allergy - overactive immune response to environmental factors
Describe the epidermal barrier in eczema?
Impaired
What are the pathological features of eczema?
- Spongiosis (intercellular oedema) within the epidermis.
- Acanthosis (thickening of the epidermis).
- Inflammation - Superficial perivascular lymphohistiocytic infiltrate
What differences exist between acute and chronic eczema?
Acute:
Erythema
Oedema within the dermis
Intraepidermal vesicles and occasionally bullae
Infiltration of the epidermis with lymphocytes is common
Chronic: Less vesiculation and oedema
Lichenification: Skin thickening (epidermal acanthosis) with pronounced skin markings
Dyspigmentation: Hyper and hypopigmentation can occur
What are causes for acute flares of eczema?
•Viral illness - or period poor health
•Stress
•Environmental triggers –
- heat,
- cold
- allergens (house dust mite, cat/dog dander)
- Food allergies
What are the clinical features of eczema?
•Itch, redness, scaling, papules, vesicles
Flexural - however it can involve all body sites (babies usually starts on the face)
Chronic changes - lichenification, plaques, fissuring
What are the exogenous forms of eczema?
Contact dermatitis: Irritant, allergic
Lichen simplex - chronic itching and scratching
Photoallergic or photoaggravted eczema
What are the endogenous causes of eczema?
Atopic
Discoid
Venous
Seborrhoeic dermatitis
Pompholyx
Juvenile plantar dermatitis
Asteatotic
What type of hypersensitivty is assocaited with allergic contact dermatits?
Type 4
Delayed hypersensitvity can take up to 48-72 hours
T cells are sensitised to environmental allergen - once activated stimulate mast cell degranulation, vasodilation and neutrophils
What injures the skin in irritant contact dermatitis?
Friction
Environmental factors:
- Cold
- Over exposure to water
- Chemicals such as acids, alkalis, detergents and solvents
What are the relevant investigations for eczema?
Patch testing
Viral or bacterial swab for microscopy and culture to investigate for secondary infection
Scrapings to exlude fungal inections
Describe seborrhoeic eczema - Features in areas rich in supply of sebaceous glands (scalp, face, upper trunk
Erythomatous scaly rash
Associated with and may be due to overgrowth of pityrosporum yeasts
When severe it may resemble psoriasis
Severe or recalcitrant seborrhoeic eczema may be a marker of immunodeficiency including HIV infection
What is herpes herpeticum?
Disseminated viral infection of herpes simplex
