Psoriasis, Eczema and Pruritus Flashcards
Epidemiology of Psoriasis (4)
prevalance: 2% in caucasians
F>M
peak incidence in 20s and 50s
30% have FHx
Pathology of psoriasis (4)
T IV hypersensitivity
epidermal proliferation
T-cell driven inflammatory infiltration
Histology:
- acanthosis: epidermal thickening
- parakeratosis: nuclei in stratum corneum
- Munro’s microabscesses: neutrophils
Triggers of psoriasis (5)
Stress
infection-esp. strep
trauma-Kobner
drugs: beta-b, Li, anti-malarials, EtOH
smoking
Presentation of psoriasis (3)
Plaques
- symmetrical, well defined w. silver scale
- extensors: elbows knees
- flexors: axillae, groin, submammary-no scale
- scalp, behind ears, umbilicus, sacrum
nail changes (50%)
- pitting
- onycholysis
- subungal hyperkeratosis
10-40% develop seronegative arhtritis:
- mono/oligoarthritis-mainly affects DIPs
- asymmetrical polyarthritis
- rheumatoid-like
- psoriatic spondylitis
- arhtritis mutlians
- may>dactylitis
Psoriasis variants (3)
Guttate:
- small, salmon-pink papules w. fine silvery scale
- mainly on trunk
- occurs in children. commonly after strep infection
Pustular:
- eruption of tiny sterile pustules
- may be localised to palms and soles
erythroderma and generalised pustular:
- generalised exfoliative dermatitis
- severe systemic upset: temperature, raised WCC and dehydration
- can be triggered by rapid steroid withdrawal
DDx for psoriasis (3)
tinea: asymmetrical
seborrhoeic dermatitis
Eczema
Mx of psoriasis (7)
Education: avoid triggers
Soap substitues: aqueous cream, epaderm ointment, dermol cream
emollients: Epaderm, diprobase, dermol
topical therapies:
- vit D analogues: calcipotriol
- steroids: betamethasone
- coal tar: mainly in-patient use
- dithranol
- topical retinoids: tazarotene
UV phototherapy:
- UVB
- P-UVA: more effective but increased risk skin ca.
non-biologicals:
- methotrexate
- ciclosporin
- acetretin: oral retinoid, SEs: hyperlipidaemia, hyperglycaemia
biologicals:
- infliximab
- etanercept
- adalimumab
Presentation of Eczema (3)
extremely itchy
poorly demarcated rash:
- acute: oozing papules and vesicles
- subacute: red and scaly
chronic eczema>lichenification: skin thickening w. exaggerated skin markings
Pathology of eczema
epidermal spongiosus
Features of atopic eczema (4)
TH2-driven inflammation w. increased IgE production
affects 2% of children
most children grow out of it by 13 yrs
often have strong FHx of atopy
Triggers of atopic eczema (2)
specific allergens:
- house dust mite
- animal dander
diet e.g. dairy
Presentation of atopic eczema (3)
face: esp. around eyes and cheeks
flexors: knees and elbows
can get secondary infection:
- staph: fluclox
- HSV: aciclovir
Assoc. of atopic eczema (2)
asthma
hayfever
Ix for atopic eczmea (2)
raised IgE
RAST testing: identify specific antigens
Causes of irritant contact dermatitis (3)
detergents/soaps/solvents
oils
venous stasis
(everyone is susceptible to irritants)
Features of allergic contact dermatitis (3)
TIV hypersensitivity reaction
common triggers:
- nickel
- chromate: leather
- lanolin: creams/cosmetics
locations correlates strongly w. allergen exposure
Ix for allergic contact dermatitis
Patch testing
Features of adult seborrhoeic dermatitis (3)
red scaly rash
due to yeast overgrowth
often on scalp, eyebrows, cheeks and nasolabial folds
Rx of seborrhoeic dermatitis
mild topical steroid/antifungal:
-daktacort: miconazole+hydrocortisone
Mx of atopic eczema (5)
education: avoid triggers
soap substitute:
- aqueous cream
- dermol cream
- epaderm ointment
topical steroids:
- 1%hydrocortisone for face and groin
- eumovate: can use briefly on face
- betnovate
- dermovate: briefly on thick skin e.g. palms/soles
2nd line therapies:
- topical tacrolimus
- phototherapy
- ciclosporin or azathioprine
Causes of generalised pruritus (4)
CKD
cholestasis
haematological:
- Hodgkin’s
- polycythaemia
- IDA
- leukemia
endocrine:
- DM
- hyper/hypothyroidism
- pregnancy
extremely itchy derm diseases (4)
eczema
urticaria
scabies
dermatitis herpetiformis
