Atopic Eczema/Dermatitis Flashcards
what is corenification?
loss of the nucleus during differentiation
cardinal feature of eczema?
spongiosis
oedema between keratinocytes
inflammatory cell infiltrate
what separates types of eczema?
different pathogenic mechanisms
different causes
acute eczema phase?
papulovesicular
erythematous lesions
oedema
ooze, scaling and crusting
chronic eczema phase?
thickening (lichenification)
elevated plaques
increased scaling
is eczema well defined?
no, ill defined
epidermal inflammation
what types of eczema/dermatitis cause spongiotics dermatitis?
contact allergic
contact irritant
atopic
photosensitive
what types of eczema/dermatitis cause spongiotic dermatitis and eosinophils?
drug related
what is lichen simplex dermatitis?
no underlying skin disease
only happens if you scratch the skin enough
causes spongiotic dermatitis and external trauma
what is stasis/venous dermatitis?
in people with peripheral oedema
physical trauma to the skin due to hydrostatic pressure causes spongiotic dermatitis and extravasion of RBCs
most common contact allergic dermatitis?
nickel
feature of contact allergic dermatitis?
often sharp cut off
is weeping eczema acute or chronic?
acute
why do vesicles/bullae occur in eczema?
acute spongiosis fluid production occurring so rapidly that they form blisters
immunopathology of contact allergic dermatitis?
Langerhans cells in epidermis process antigen and then present it to Th cells in dermis
sensitised Th cells migrate into lymphatics and then to regional nodes where antigen presentation is amplified
on next exposure to antigen, sensitised T cells proliferate and migrate to/infiltrate skin causing dermatitis
how is contact allergic dermatitis diagnosed?
patch testing
contact allergic vs contact irritant?
allergic = specific immune response irritant = non-specific physical irritation response (not immune)
if specific, localised reaction with obvious cause (e.g under a ring)?
often a contact allergic but could be irritant
can irritant contact dermatitis overlap with allergic contact?
yes can also overlap with atopic dermatitis
underlying disease makes irritant reaction more severe
what implications can dermatitis have?
impact on career choice
advise for irritant dermatitis?
create a barrier (e.g gloves)
give 5 possible effects of hand dermatitis?
erythema scaling fissures lichenification (thickening of skin) nail dystrophy crusting
what is nappy rash?
irritant contact dermatitis to urine
how can irritant dermatitis and fungal infection be differentiated?
fungal infections tend to favour flexures
dermatitis often has sparing of flexures
sign of fillagrin mutation?
increased creasing on hands of children which should be smooth
what is the cycle of pruritic?
itch > more scratching > more itchy > more scratching
what are the features of atopic eczema?
pruritis
ill defined erythema and scaling with generalised dry skin
seen most in flexures
associated with atopic disease
what is fissuring below the ears pathopneumonic of?
atopic eczema
what does eczema look like in darker skin?
papular appearance
extensive lichenification
hypertrophic scarring
ill defined erythema and scale still present but less obvious
chronic changes in atopic eczema?
lichenification
excoriation
secondary infection
common secondary infection in atopic eczema?
staph aureus (golden crusting) atopic people more likely to carry staph aureus rather than epidermidis
what is eczema herpeticum?
eczema infected with herpes simplex virus
causes monomorphic, punched out lesions all over body (like cold sores)
how is eczema herpeticum treated?
a..tivir
how is eczema diagnosed?
itch plus 3 or more of:
- flexural rash
- history of flexural rash
- personal history of atopy
- dry skin
- onset before 2 years old
how is eczema treated?
- emollients
- avoid irritants
- topical steroids
- treat infection
- phototherapy (UVB)
- immunosuppresants (azathioprine)
- biologic agents
what causes atopic eczema?
impaired skin barrier function
environmental factors
immunology
possible fillagrin mutation
what is discoid eczema?
well defined, circular lesions
often get infected
patients are often atopic
features of photosensitive eczema?
chronic actinic dermatitis
clear cut off seen at border of eczema (e.g at collar, sleeves etc)
can also be caused by photosensitising drugs
what causes stasis eczema and what does it look like?
erythema around varicose veins hydrostatic pressure oedema red cell excavation often at ankles
what is seborrheic dermatitis?
“cradle cap”
atopic eczema on scalp with co-infection with fungus
pompholyx eczema?
sudden acute flare of any subtype of eczema with little vesicles (spongiotic)
what causes lichen simplex?
normal skin
thickening and lesions caused by scratching
treated with topical steroids
how do you differentiate between allergic and irritant contact dermatitis?
occupational, family and social history
patch testing
is pompholyx acute or chronic?
acute
can herpes simplex and staph aureus occur together?
yes
punched out lesions with golden crusting
