eczema Flashcards
Definition of eczema
pruritic papulovesicular skin reaction to endogenous or exogenous agents
Types of eczema
exogenous - irritant, contact, phtotoxic
endogenous - atopic, seborrhoeic, varicose, pompholyx (dyshidrotic), lichen simplex
what is lichen simplex
thickening of the skin, secondary to the cycle of itch - scratch - itch
characterised by well demarcated hyperpigmented lichenified plaques
aetiology of irritant eczema
prolngued skin contact with a cell damagiong irritant
eg ammonia in a nappy rash
detergent, soap, oil, solvents, alkali, water (if repeated)
aetiology of contact eczema
type IV delayed hypersensitivity to allergen
eg nickle (jewellery, watches, coins, keys),
chromate (Cements, leather),
rubber,
perfumes,
lanolin (creams and cosmetics)
latex
plants (primulas)
tropical neomycin
framycetin
antihistamines
anaesthetics - haemorrhoids cream
pathology of atopic eczema
2 models
- impaired epidermal barrier function from intrinsic structural and functional skin abnormalitues - predominant model
- immune function disorder - langerhans cells, T cells and immune effector cells modulate an inflammatory response to env factors (traditional model)
causes of atopic eczema
genetic - FHx of atopy
infection - staphs colonise lesion - suggestied by weeping, crusting or pustules
allergens - huse dust mite, animal dender, food allergy (rare)
if clear trigger with immediate symptoms consider IgE test
aetiology of seporrhoeic eczema
Pityrosporum yeast
severe if HIV +VE
aetiology of varicose eczema
fluid collects in tissues and activates the immune response
RF:
* dvt
* cellulitis
* chronic swelling
* varicose veins
* stasis ulcers
epidemiology of eczema
contact - 4%
atopic - onset commonly in 1st yr of life, childhood incidence 10-20%
presenting symptoms of eczema
itching - can be severe
heat
tenderness
redness
weeping
crusting
important to ask in eczema history
family/personal history of atopy eg asthma, hay fever, rhinits
signs of acute eczema
poorly demarcated erythematous oedematous dry scaling patches
(less scaly than psoriasis)
papules
vesicles with exudation and crusting
excoriation marks
signs of chronic eczema
thickened epidermis
skin lichenification
fissures
changes in pigmentation
signs of contact and irritant eczema
eczema rn when irritant/allergen comes in contact with the skin
autosensitisation (spread to other sites) can occur in contact.
contact - often clear cutoff where contact ends
irritant - hands, redness +- weeping precedes dry fissuring
sign of atopic eczema
affects face and flexures
signs of seborrhoeic eczema
yellow greasy scales on erythematous plaques
particularly in:
- nasolabial folds
- eyebrows
- scalp - dandruff
- presternal area
- cheeks
- flexures
sign of pompholyx eczema
acute and often recurrent painful vesicobullous eruption on palms and soles
sign of varicose eczema
lower legs
associated with marked varicose veins
signs of nummular eczema
well defined coin shaped, on leg and trunk
1-3cm
2 clinical forms:
- exudatove acute - oozy papules, blisters, plaques
- dry - subacute or chronic erythematous, dry plaques
signs of asteatotic eczema
dry
crazy paring pattern
investigations for eczema
contact
- skin patch testing - disc containing postulated allergen is diluted and applied to back for 48hr.
- +VE - allergen = raised red lesion
atopic
- lab testing, including IgE levels not used routinely and not recommended
discoid
- bacterial swabs - staph aureus
- scrapings fro mycology (because look similar to ringworm)
- patch testing
dyshidrotic
- skin scrapings for mycology
- patch testing in chronic or atypical cases
- skin biopsy - rare - show spongiotic eczema
herpeticum
- viral swab - viral culture, direct flurescent Ab stain, PCR, Tzank smear showing epithelial multinucleated giant cells and acantholysis
- bacterial swabs
- skin biopsy
swab for infected lesions - bacteria, fungi, virus
diagnosis for atopic eczema
itchy skin and >=3 of:
- onset <2yrs
- past flexural involvement
- history of generally dry skin
- personal history of other atopy (or atopy in 1st degree relative if <4yr)
- visible flexural dermatitis (or on cheeks/forehead and outerside of limbs if <4yrs)
may be lichenification or postinflammatory hyper/hypopigmentation
spares the nappy area
aetiology of nummular/discoid eczema
unknown
some cases associated with Staphylococcus aureus
eruption can be precipitated by:
- localised injury - scratch, insect bite, thermal burn
- impetigo or wound infection
- contact dermatitis
- dry skin
- varicose veins
RF for discoid/nummular eczema
more common in older adult males and younger adult female
in males association with chronic alcoholism
drug induced
signs of dyshidrotic eczema
vesicles or bullae (blisters) on hand/soles
intense itch/burning
blisters may peel off and skin then red, dry and has painful fissures
aetiology of dyshidrotic eczema
multifactorial
related to sweating - flare in hot weather, humid conditions or emotional upset
genetics
contact with irritants
contact allergy - nickle and allergens
inflammatory dermatophyte (tinea) infections - dermatophytid
adverse drug reactions - most often immunoglobin therapy
RF for dyshidrotic eczema
female
palmoplantar hyperhidrosis
personal/FHx of atopic eczema
what is eczema herpeticum
disseminated viral infection
symptoms of eczema herpeticum
fever
clusters of itchy blisters or punched-out erosions
any site, most common on face and neck
swollen lymph nodes
monomorphic blisters
filled with clear yellow fluid or thick purulent material.
often blood-stained i.e., red, purple or black.
New blisters have central dimples (umbilication).
may weep or bleed.
Older blisters crust over and form sores (erosions)
heal over 2–6 weeks.
In severe cases where the skin has been destroyed by infection, small white scars may persist long term.
blisters can occur in normal skin or sites actively or previously affected by atopic dermatitis or another skin disease
Secondary bacterial infection with staphylococci or streptococci may lead to impetigo and cellulitis.
Severe eczema herpeticum may affect multiple organs, including the eyes, brain, lung, and liver. It can rarely be fatal.
causes of eczema herpeticum
complication of atopic dermatitis
HSV1 or 2
during 1st episode of infection - 5-12days after contact
repeated episodes unusual, can complicate recurrent herpes
RF of eczema herpeticum
infants and children with atopic dermatitis - reduced immunity
mx of eczema
- education
- emollients
- topical steroids - acute flare and mod-severe disease
- topical calcineurin inhibitors - tacrolimus - dermatologist
- antimicrobials if required
- phototherapy - if not responded to topical
- systemic - ciclosporin, azathioprine, methotrexate - refractory eczema
- biologics - Il4 and Il13 inhibitor
mx of itch in eczema
short term - sedating antihistamines - hydroxyzine or chlorphenamine
