Eczema Flashcards
What is eczema?
Inflammatory skin condition which commonly affects flexural areas (areas which experience stretching/movement)
aka Atopic dermatitis
What causes eczema to develop?
Wide range of external (exogenous) or internal (endogenous) factors can induce the condition
No known ‘cause’ for it to happen - but its a combination of Genetic and environmental factors
If these cause Barrier dysfunction + Inflammation = eczema
Give the clinical definition of atopic eczema
An itchy skin condition of 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 (or in 1st degree relative before age 4)
Describe the role of genetics in the pathogenesis of atopic eczema
Many genes implicated
Key role for the Filaggrin gene
Atopic family history important due to genetic relevance (atopic eczema, asthma hay fever (allergic rhinitis), food allergy)
Which layer of our skin is implicated in eczema and how?
Epidermis
Epidermal barrier dysfunction is key in the pathogenesis of eczema
Describe the pathology of atopic eczema
Characterised by 3 things:
Spongiosis! (intercellular oedema)
Acanthosis (thickening of epidermis)
Inflammation (Superficial perivascular lymphohistiocytic infiltrate)
Describe the clinical features of eczema
Rash:
- Itch!
- Red
- Swollen/raised
- ± blisters
Distribution:
- Flexures - neck, eyelids, face, hands, feet
- Tends to spare nappy area
May have acute or chronic changes
What acute changes may be present in eczema?
- Pruritus, Erythema, Scale, Papules, Vesicles
- Exudate, crusting, excoriation
What chronic changes may be present in eczema?
– Lichenification, Plaques, Fissuring
So we have acute and chronic eczema
What other types are there?
(think there can be a lot of overlap)
Exogenous:
-
Contact dermatitis
- Irritant
- Allergic
- Dermatitis w/ Lichen simplex (LSC)
- Photoallergic or photoaggravated eczema
Endogenous:
- Atopic
- Discoid
- Venous
- Seborrhoeic dermatitis
- Pompholyx
- Juvenile plantar
- Asteatotic
What causes allergic contact dermatitis and how would it present?
Type 4 hypersensitivity reaction
Delayed hypersensitivity – can take 48-72 hrs to develop reaction
Often in very localised areas which indicates what the allergen is (ie metal on necklace causes red ring on neck)
What irritants precipitate contact dermatitis?
1) Friction
2) Environmental factors:
- Cold
- Over-exposure to water
- Chemicals (cleaners etc)
Note - irritant dermatitis is a form of contact dermatitis which is pretty fair enough if you think about it
What is patch testing?
Patch applied to skin with spots of potential allergens (same allergens given to all patients)
Applied monday, removed wednesday, checked friday
What is Seborrhoeic dermatitis?
Type of dermatitis which affects people around 50 years old and babies less than 6 months old usually
Basically very dandruffy rash. Patterns different between infants and adults
How does Seborrhoeic dermatitis present in infants?
Distinctive pattern
Predilection for scalp, proximal flexures.
<6months age usually.
Often clears within weeks of treatment
