Eczema Flashcards
(33 cards)
what is it?
a group of inflammatory skin diseases affects 10% of the population
is eczema dermatitis?
kinda they are skin lesions with similar clinical and pathological features but they have different pathogenic mechanisms
what is the pathogenesis of eczema
complex trait
multiple genetic and environmental factors
immunological factors
skin barrier function
most important genes - involved in filaggrin
how does it present?
itchy ill-defined (unlike psoriasis) erythematous scaly spongiotic intra-epidermal oedema
what are the 2 phases of presentation?
acute phase - papulovesicular erythematous lesions, spongiosis, ooze or scaling and crusting
chronic phase - thickening (lichenification), elevated plaques, increased scaling
How is eczema managed?
1st line - emollients
2nd line - phototherapy
3rd line - immunosuppressants (systemic immunosuppressants, biologic agents)
treatment progression is step-wise but infection should be treated at anytime
irritants e.g. shower gel/soaps should be avoided
what is atopic eczema also known as
atopic dermatitis
what causes atopic eczema?
genetic (strong material influence)
mutations in fillagrin gene which decrease AMP in the skin
moisturiser is important
environmental factors can trigger
pathology of atopic eczema
defective barrier
allows access/ sensitisation to allergen
promotes colonisation by micro-organisms
stressed keratinocytes attract T cells
dendritic cells
other keratinocytes
macrophages and mast cells
how does atopic eczema present?
most common in children pruritis (can cause sleep disturbance) ill-defined erythema and scaling generalised dry skin flexural distribution
conditions associated with atopic eczema
other atopic diseases
asthma
allergic rhinitis
food allergy
What are the chronic changes in atopic eczema?
lichenification
excoriation
secondary infection (common, crusting (gold) indicates staph aureus infection)
how is it diagnosed?
itching + 3 or more of:
visible/history of a flexural rash (cheeks and extensor surfaces in infants)
personal history of atopy - 1st degree relative of they are under 4
generally dry skin
onset before 2
what is contact allergic dermatitis?
a very common reaction in response to chemicals, topical therapies, nickel, plants, things in the air
what is the immunopathology of contact allergic dermatitis?
langerhans cells in the epidermis process the antigen (increasing immunogenicity)
processed antigen is then presented to Th cells in the dermis
the Th cells migrate through lymphatics into regional nodes where antigen presentation is amplified
T cells then proliferate and infiltrate/ migrate to the skin = dermatitis
how is contact allergic dermatitis diagnosed?
patch testing
reactions are checked after 96hrs (4 days)
what is irritant (contact) dermatitis?
a very common condition - sometimes hard to distinguish from allergic contact dermatitis
Non-specific physical irritation rather than a specific allergic reaction e.g. soap/cleansing productions, water, oil
what aspect of social history is key in irritant (contact) dermatitis?
occupation - as it can affect the condition and having the condition can affect their ability to work
what is eczema herpeticum?
a condition that needs to be recognised early
it is caused by the herpes simplex virus
presents with monomorphic punched out lesions
discoid eczema
well-defined, patient are also atopic
photosensitive
chronic actinic dermatitis
cut-off collar
patients are often also atopic
can be secondary to photosensitising drugs
stasis eczema
secondary to hydrostatic pressure
oedema
red cell extravasation
pomopholyx eczema
spongiotic vesicles
lichen simplex
well-defined edges
