Psoriasis, Eczema and Pruritus

Question 1

Epidemiology of Psoriasis (4)

Answer 1

prevalance: 2% in caucasians

F>M

peak incidence in 20s and 50s

30% have FHx

Question 2

Pathology of psoriasis (4)

Answer 2

T IV hypersensitivity

epidermal proliferation

T-cell driven inflammatory infiltration

Histology:

• acanthosis: epidermal thickening
• parakeratosis: nuclei in stratum corneum
• Munro’s microabscesses: neutrophils

Question 3

Triggers of psoriasis (5)

Answer 3

Stress

infection-esp. strep

trauma-Kobner

drugs: beta-b, Li, anti-malarials, EtOH

smoking

Question 4

Presentation of psoriasis (3)

Answer 4

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

Question 5

Psoriasis variants (3)

Answer 5

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

Question 6

DDx for psoriasis (3)

Answer 6

tinea: asymmetrical

seborrhoeic dermatitis

Eczema

Question 7

Mx of psoriasis (7)

Answer 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

Question 8

Presentation of Eczema (3)

Answer 8

extremely itchy

poorly demarcated rash:

• acute: oozing papules and vesicles
• subacute: red and scaly

chronic eczema>lichenification: skin thickening w. exaggerated skin markings

Question 9

Pathology of eczema

Answer 9

epidermal spongiosus

Question 10

Features of atopic eczema (4)

Answer 10

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

Question 11

Triggers of atopic eczema (2)

Answer 11

specific allergens:

• house dust mite
• animal dander

diet e.g. dairy

Question 12

Presentation of atopic eczema (3)

Answer 12

face: esp. around eyes and cheeks
flexors: knees and elbows

can get secondary infection:

• staph: fluclox
• HSV: aciclovir

Question 13

Assoc. of atopic eczema (2)

Answer 13

asthma

hayfever

Question 14

Ix for atopic eczmea (2)

Answer 14

raised IgE

RAST testing: identify specific antigens

Question 15

Causes of irritant contact dermatitis (3)

Answer 15

detergents/soaps/solvents

oils

venous stasis

(everyone is susceptible to irritants)

Question 16

Features of allergic contact dermatitis (3)

Answer 16

TIV hypersensitivity reaction

common triggers:

• nickel
• chromate: leather
• lanolin: creams/cosmetics

locations correlates strongly w. allergen exposure

Question 17

Ix for allergic contact dermatitis

Answer 17

Patch testing

Question 18

Features of adult seborrhoeic dermatitis (3)

Answer 18

red scaly rash

due to yeast overgrowth

often on scalp, eyebrows, cheeks and nasolabial folds

Question 19

Rx of seborrhoeic dermatitis

Answer 19

mild topical steroid/antifungal:

-daktacort: miconazole+hydrocortisone

Question 20

Mx of atopic eczema (5)

Answer 20

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

Question 21

Causes of generalised pruritus (4)

Answer 21

CKD

cholestasis

haematological:

• Hodgkin’s
• polycythaemia
• IDA
• leukemia

endocrine:

• DM
• hyper/hypothyroidism
• pregnancy

Question 22

extremely itchy derm diseases (4)

Answer 22

eczema

urticaria

scabies

dermatitis herpetiformis