Dermatitis Flashcards
what is the acute phase characterised by
erythema, oedema, vesicular/bullous lesions and exudates
how are secondary infections heralded
golden crusting
what is the chronic phase characterised by
scaling, dryness, elevated plaques and lichenification
what effect can inflammation in the skin have on skin pigmentation
post inflammatory hypo/hyper pigmentation
what type of hypersensitivty reaction is contact dermatitis
4
name some common allergens for contact dermatitis
nickel, perfume, chrome (cement), latex
time frame for contact dermatitis
48 hours
contact dermatitis immunology
antigens penetrate epidermis and are picked up by Langerhans cells - T cells become sensitised. On subsequent exposure an allergic reaction occurs due to accumulation of sensitised T cells
how can specific substances be tested for type 4 hypersensitivity
patch testing
treatment for contact dermatitis
topical steroids and emollients
what are the different strengths of topical steroids available
hydrocortisone 1% - mild
eumovate - moderate
betnovate - potent
dermovate - very potent
irritant dermatitis
- mechanism
- when does it occur
non specific physical irritation - occurs when chemicals/physical agents damage the epidermis faster than the skin is able to repair the damage - no immune involvement
dermatitis occurs soon after exposure and severity varies with concentration and length of exposure
how does atopic eczema typically present
- chronic
in childhood, initially with facial (cheeks) and subsequently flexural limb involvement
ill defined erythema and scaling
chronic changes: lichenification induces skin markings, excoriation caused by scratching, secondary infection
what is atopic eczema often associated with
other atopic diseases eg asthma, food allergy
atopic eczema history
tends to go back to childhood
what does golden crusting indicate
transference of S Aureus by scratching
treatment of eczema
emolients and topical steroids
avoid irritants including shower gels/soaps
treat infection
phototherapy
systemic immunosuppressants
would you use UVA or UVB for phototherapy for eczema
UVB
aetiology of atopic eczema
multiple genetic and environmental factors
is there a genetic predisposition for eczema
yes common - filaggrin gene defects lead to impaired skin barrier function
what does filaggrin mutation cause
ichythyosis vulgaris - skin doesnt shed its dead skin cells
discoid eczema
- presentation
- aetiology
intensely pruritic coin shaped lesions commonly on limbs
cause is unknown, can be assoicated with S. Aureus and occur in atopic eczema
eczema herpeticum
- history
- presentation
HSV infection that occurs at sites of skin damage eg burns, long term use of topical steroids
frequently there is a history of close contact with adult herpes labialis (cold sores)
small punched out looking lesions
venous dermatitis
- aetiology
occurs on lower legs of patients with venous insufficiency
- due to fluid collecting in the tissues and activation of the immune response
venous dermaitis presentation
venous eczema presents as itchy, red blistered and crusted plaques, or dry fissured and scaly plaques on one or both legs
patients typically also have peripheral oedema and ulceration
also: haemosiderin deposits and lipodermatosclerosis
what can venous dermatitis lead to
2y eczema (spread to body)
cellulitis
contact allergy to treatments
where does seborrhoeic dermatitis effect
areas of skin with lots of sebaceous glands eg scalp, eye brows, nasolabial folds, upper sternum and back
there is often dandruff like scaling on the scalp
describe the seborrhoeic dermatitis lesions
fine, greasy scales on erythematous background
flat patches
what is a differentiating feature between seborrhoeic dermatitis and psoriasis
SD is flat patches whereas psoriasis tends to be raised plaques
pompholyx eczema
- presentation
- cause
- clinical course
itching spongiotic vesicles on fingers, palms and soles
unknown cause
clinical course ranges from self limiting to chronic, severe and debilatating
in which patients does pampholyx eczema tend to cocur
those with nickel allergy
lichen simplex
localised area of lichenification produced by rubbing due to chronic localised itch
primary itch may be due to eczema, psoriasis etc
photosensitive eczema cause
can result from drugs taken internally or substances in contact with skin also plant material and sunlight obvs
