Eczema Flashcards
What is eczema?
it is a common inflammatory skin condition, commonly in babies and children
What are the 2 categories of eczema and what subtypes of eczema do they encompass?
- Endogenous
- atopic eczema
- seborrhoeic eczema
- discoid eczema
- chronic eczema
- venous eczema
- asteatotic eczema
- exogenous
- irritant contact eczema
- allergic contact eczema
what is atopic eczema?
type of eczema that usually starts <2 years old and often associated with other atopic diseases
How do you diagnose atopic eczema?
itchy skin condition in the last 12 months
Plus 3 of the following:
- onset before age 2
- history of flexural involvement
- history of generally dry skin
- history of another atopic disease (asthma/hayfever)
- history of 1st degree relative if under 4yrs
what is the aetiology of eczema?
- genetics- many genes implicated but deficiency in filaggrin gene is key
- epidermal barrier dysfunction
- environmental factors
what is atopy?
genetic tendency to develop allergic diseases ie asthma, eczema, hayfever
in acute eczema, what do keratinocytes look like histologically?
keratinocytes are swollen with increased intercellular fluid –> ‘spongiosis’
in chronic eczema, what do keratinocytes look like histologically?
little oedema but prominent thickening of the epidermis ‘acanthosis’ and scaling ‘hyperkeratosis’
what are clinical features ie symptoms and signs of eczema?
- itchy, erythematous, scaly patches, especially in flexures
- lichenification common
- fissuring
what is lichenification?
when skin thickens from scratching
What type of reaction is allergic contact dermatitis (eczema)?
type 4 hypersensitivity - delayed type, takes 48-72 hours for rash to develop
what is the pathogenesis of allergic contact dermatitis?
- antigen presenting cells take allergen to LN and present to naïve T cells
- clonal expansion of T cells, and released into bloodstream
- when these T cells next encounter hapten –> mast cell degranulation, vasodilatation & neutrophils
what is irritant contact dermatitis mainly caused by?
- friction
- environemental factors ie cold, over exposure to water, chemicals (acids, alkalis etc)
what investigation should be done in anyone with contact dermatitis?
patch testing
how does patch testing work?
- 41 potential allergens applied monday on patient’s back
(standard allergens applied to all patients)
- remove wednesday
- re-assess friday
What is seborrheoic dermatitis (eczema)?
eczema which occurs in greasy body areas
what are the features of seborrhoeic dermatitis in infants?
- predilection for scalp, proximal flexures
- <6 months age usually
- often clears within week of treatment
- what is discoid eczema
- where is it most likely to develop?
- circular eczema plaques
- may develop at sites of trauma/infection
What is pompholyx/vesicular eczema?
- occurs in palms and soles
- very itchy
- more common <40 y/o
what is asteatotic eczema?
- very dry skin with cracked scaly appearance
- most commonly shins affected
- brought on by the cold / excessive washing & soaps
what is venous eczema?
- usually affects those with varicose veins or history of a venous thrombosis
- usually coexistant signs of venous hypertension - oedema, increased venous pressure
- ankle and lower leg involved
