Derm (Psoriasis) Flashcards
Epidemiology of psoriasis
- Incidence between 1-3%, with greater incidence in Europe and North America than East and South-East Asia
- Estimated 40,000 people in Singapore with psoriasis
- Same incidence in males as in females
- Bimodal distribution-75% have onset before age of 40
- Two peak ages of onset at 20 -30 and again at 50-60
Psychosocial burden of psoriasis
- 33% experience depression and anxiety
- 10% attempt suicide
- 1 in 5 report being rejected due to their condition
Eiology of psoriasis
- Fam Hx/genetic: TNFa
- Infections: B-hemolytic streptococci, HIV -> 2wks after viral of streptococci infection
- Hormonal: early age of onset in females
- psychogenic: stress
- drugs: lithium, b-blockers (timolol)
- Koebner phenomenon -> psoriasis developing after tattoo
- smoking, alcohol, obesity might be factors too
Comorbidities assoc with psoriasis
- crohn disease
- psoriatic arthritis
- depression, alcoholism
- metabolic syndrome: CVD risk, obesity, HTN etc
- increases rate of mortality
Clinical presentations of psoriasis
- Lesions: ertythematous, red-violet colour, at least 0.5cm in diameter, well demarcated, typically covered by silver flaking scales
- Skin involvement: knees, elbows (extensor distribution) or generalised over a wide BSA.
Mild: <=5% BSA
Mod: PASI >=8
Sev: PASI >=10 or BSA >= 10%. - Pruritis: >50% will experience
- Plaques raides from skin
Inverse psoriasis: affects flexor surfaces, no scales
Nail psoriasis: pitting, complete nail distrophy
What is guttate psoriasis?
- Gutta (Greek)-a droplet
- Commonest in childhood
- 2 weeks post streptococcal (haemolytic group A) pharyngitis or tonsillitis
- Centripetal distribution (mainly on torso then spread to arm and leg)
- In children usually self- limiting
- Approx. 40% develop chronic plaque psoriasis
- look like chicken pox
What is psoriatic arthritis (PsA)?
- An inflammatory arthritis associated with psoriasis
- Rheumatoid factor negative
- Rheumatoid nodules absent
- Develops after onset of psoriasis (~10yrs ltr) but can appear first in some pts
- TNF-a and HLA-CW6 is linked to PsA and psoriasis -> use of MTX + NSAIDs
- Swollen-like inflammation in joints, severe deformity in hand joints
What are the goals of tx of psoriasis?
- Minimizing or eliminating the signs of psoriasis, such as plaques
- Alleviating pruritus and minimizing excoriations
- Reducing the frequency of flare ups
- Ensuring appropriate management of co-morbid conditions
- Avoiding or minimising adverse effects
- Providing cost-effective therapy
- Guidance and counselling as needed
- Maintain or improving the patient’s quality of life
What to counsel to patients with psoriasis?
- nature of disease (chronic skin disorder?)
- no cure
- treatment is suppressive, not curative
- not contagious
What are the non-pharm management of psoriasis?
- stress reduction
- moisturisers
- oatmeal baths
- sunscreens
Overview of pharm management strategies for psoriasis (excluding biologics)
Mild (75%): TOP CS, TOP Vitamin D3 analogue, Tazarotene, Dithranol, Coal tar, Keratolytic (eg. salicylic acid), emollients
Mod: PUVA or UVB phototherapy
Severe: hydroxyurea, MTX, cyclosporin, aeitretin
Treatment algorithm for mild-mod psoriasis
first line: topical agents
if ineffective: topical agents + phototherapy.
If ineffective: topical agents + systemic agents
All of them shld add on moisturiser too.
What topical corticosteroids is used for psoriasis?
hydrocortisone 1% or 2.5%: cream, lotion, ointment
What is the use of vitamin D3 analogues in psoriasis?
- First line monotherapy or in combination regimens
- Effective as all but the most potent TCS
- Calcipotriol, calcitriol, tacalcitol
- Binding to vitamin D receptors which results on inhibition of keratinocyte proliferation and enhancement of keratinocyte differentiation
- Inactivated by salicylic acid
What are the side effects of vitamin D3 analogues?
- common: mild irritant contact dermatitis, burning, pruritis, edema, peeling, dryness, erythema
- systemic: hyperCa, parathyroid hormone depression, impaired renal func, impaired Ca metabolism
What is the use of retinoids in psoriasis?
- Tazarotene acts by normalising abnormal keratinocyte differentiation, diminishing keratinocyte hyperproliferation and clearing the inflammatory infiltrate in the psoriatic plaque
- Tazarotene 0.1% gel has similar efficacy to Calcipotriol 0.05% cream but less effective than Clobetasol propionate 0.05% cream
- Tazarotene may be combined with TCD to increase efficacy
- Tazarotene-apply once a night and avoid sun exposure
- Tazarotene is contraindicated in pregnancy unless effective contraception is used at the same time
What are the side effects of tazarotene?
- high incidence of irritation at site (can be reduced by using cream formulation or low conc)
- burning
- itching
- erythema
What is the use of coal tar in psoriasis?
- keratolytic, anti-proliferative, may have anti-infl.
- bethamethasone valroate more effective altho coal tar has similar efficacy to calcipotriol.
- conc of 0.5% - 5% is considered safe
- not well accepted due to black appearance, smell, staining of clothes
- limited efficacy
- SE: acne, local irritation, phototoxicity
What is the use of salicylic acid in psoriasis?
- keratolytic properties
- use with combi of TCS as it helps enhance steroid penetration into skin, increasing efficacy
- not used w UVB light phototherapy due to filtering effect of SA that reduces efficacy of phototherapy
- Salicylic acid 2-3% is used for psoriasis
Note: 15-27% for viral warts and corns. 0.5% for acne as cleanser
What is the use of phototherapy and photochemotherapy?
- used w crude coal tar
- treat psoriatic lesions
- PUVA is more effective than UVB but risk of skin cancer is higher so is less used
Treatment algorithm for mod-sev psoriasis
First line: systemic agent +/- TOP agent or phototherapy, consider BRM (costly) if comorb exists
If ineffective: more potent systemic agent
If ineffective: biological response modifier (BRM) +/- other agents
Moisturisers shld be used tgt for all.
What systemic treatments are available?
- Acitretin
- MTX
- Biologics (eg. Infliximab, Tofacitinib)
What is the use of acitretin and its SE in psoriasis
- less effective than MTX when used as monotherapy but initial response may be more rapid for severe psoriasis
- replaced with isotretinoin now due to SE
- teratogenic unless birth control is used and 2yrs after discontinuing
- alcohol shld be avoided and after 2months of discontinuation
SE: nail thinning, diffuse hair loss, dryness of eye, chapped lips, angular cheilitis, xerosis, burning. Less common: retinoid dermatitis, decreased colour vision, photosensitivity
What is the use of MTX in psoriasis?
- more efficacious than acitretin and similar efficacy to cyclosporine.
- direct anti-infl effect due to effect on T-cell gene expression
- slow down growth of skin cells to stop scales
- inhibit folate biosynthesis
Other conditions which MTX is used to treat: atopic eczema, bullous pemphigoid, psoriasis
