Eczema

Question 1

what is it?

Answer 1

a group of inflammatory skin diseases affects 10% of the population

Question 2

is eczema dermatitis?

Answer 2

kinda they are skin lesions with similar clinical and pathological features but they have different pathogenic mechanisms

Question 3

what is the pathogenesis of eczema

Answer 3

complex trait
multiple genetic and environmental factors
immunological factors
skin barrier function
most important genes - involved in filaggrin

Question 4

how does it present?

Answer 4

itchy 
ill-defined (unlike psoriasis)
erythematous
scaly 
spongiotic intra-epidermal oedema

Question 5

what are the 2 phases of presentation?

Answer 5

acute phase - papulovesicular erythematous lesions, spongiosis, ooze or scaling and crusting
chronic phase - thickening (lichenification), elevated plaques, increased scaling

Question 6

How is eczema managed?

Answer 6

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

Question 7

what is atopic eczema also known as

Answer 7

atopic dermatitis

Question 8

what causes atopic eczema?

Answer 8

genetic (strong material influence)
mutations in fillagrin gene which decrease AMP in the skin
moisturiser is important
environmental factors can trigger

Question 9

pathology of atopic eczema

Answer 9

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

Question 10

how does atopic eczema present?

Answer 10

most common in children 
pruritis (can cause sleep disturbance)
ill-defined erythema and scaling 
generalised dry skin 
flexural distribution

Question 11

conditions associated with atopic eczema

Answer 11

other atopic diseases
asthma
allergic rhinitis
food allergy

Question 12

What are the chronic changes in atopic eczema?

Answer 12

lichenification
excoriation
secondary infection (common, crusting (gold) indicates staph aureus infection)

Question 13

how is it diagnosed?

Answer 13

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

Question 14

what is contact allergic dermatitis?

Answer 14

a very common reaction in response to chemicals, topical therapies, nickel, plants, things in the air

Question 15

what is the immunopathology of contact allergic dermatitis?

Answer 15

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

Question 16

how is contact allergic dermatitis diagnosed?

Answer 16

patch testing

reactions are checked after 96hrs (4 days)

Question 17

what is irritant (contact) dermatitis?

Answer 17

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

Question 18

what aspect of social history is key in irritant (contact) dermatitis?

Answer 18

occupation - as it can affect the condition and having the condition can affect their ability to work

Question 19

what is eczema herpeticum?

Answer 19

a condition that needs to be recognised early
it is caused by the herpes simplex virus
presents with monomorphic punched out lesions

Question 20

discoid eczema

Answer 20

well-defined, patient are also atopic

Question 21

photosensitive

Answer 21

chronic actinic dermatitis
cut-off collar
patients are often also atopic
can be secondary to photosensitising drugs

Question 22

stasis eczema

Answer 22

secondary to hydrostatic pressure
oedema
red cell extravasation

Question 23

pomopholyx eczema

Answer 23

spongiotic vesicles

Question 24

lichen simplex

Answer 24

well-defined edges

Question 25

pathogenesis and histology of contact allergic dermatitis

Answer 25

type 4 hypersensitivity

spongiotic

Question 26

pathogenesis and histology of contact irritant dermatitis

Answer 26

trauma e.g. soap/water

spongiotic

Question 27

pathogenesis and histology of atopic dermatitis

Answer 27

genetic/environmental factors resulting in inflammation

spongiotic

Question 28

pathogenesis and histology of drug-related dermatitis

Answer 28

type 1/4

spongiotic and eosinophils

Question 29

pathogenesis and histology of photo-induced/ photosensitive dermatitis

Answer 29

reaction to UV light

spongiotic

Question 30

pathogenesis and histology of lichen simplex dermatitis

Answer 30

physical trauma to the skin (scratching)

spongiotic and external trauma

Question 31

stasis dermatitis

Answer 31

physical trauma to skin (hydrostatic pressure)

spongiotic and extravasation of RBCs

Question 32

what type of dermatitis is eczema?

Answer 32

spongiotic dermatitis

Question 33

what does spongiotic mean?

Answer 33

The spongiotic tissue reaction pattern is characterised by intercellular oedema within the epidermis (spongiosis).
widening the intercellular spaces between keratinocytes Further accumulation of fluid leads to the formation of intraepidermal vesicles.
the vesicles can be at any position in the epidermis
parakeratosis forms above the spongiosis