Psoriasis

Question 1

What is psoriasis?

Answer 1

• common, chronic inflammatory skin condition
• raised, red, (itchy), scaly plaques on extensor surfaces
• T-cell mediated abnormal immune response causing keratinocyte hyperproliferation
• strong genetic component
• link to arthritis
• subtypes eg guttate or palmar-pustular

Question 2

Epidemiology of psoriasis?

Risk factors?

Answer 2

• affect 2-4% of the population
• any age but bimodal peak at 15-25 and 50-60 years
• 3rd of patients have a relative with it
• more common in caucasians

Risk factors:

• genetic susceptibility
• smoking
• obesity
• psychological stressors

Question 3

Pathology of psoriasis?

Answer 3

keratinocyte hyperproliferation

Biopsy:

• parakeratosis (retained nuclei)
• acanthuses (thick epidermis)
• absent granular layer
• thin dermal papillae
• dilated, tortuous capillaries
• munro’s micro-abscesses
• T-cell in upper dermis

Question 4

Clinical features of psoriasis?

Types?

Answer 4

• symmetrical
• red scaly plaque (plaque is white or silvery)
• often on extensors
• scalp (behind ears), elbows, knees, anywhere

TYPES

Classical:

• 90% of cases
• well circumscribed, erythematous with silver scale >3cm
• esp extensor surface
• pain and itch (less than eczema)
• auspitz sign (bleeding on removal of scale)

Guttate:

• young onset
• often following streptococcal tonsillitis
• discoid erythematous scaly macules and plaques on TRUNK
• usually <3cm
• good prognosis, will usually resolve in several months

Palmoplanar-pustular:
- yellow brown pustules on palms and soles

Flexoral:

• plaques are erythematous but not scaly
• submammary, axillary, anogenital, umbilical
• esp women, elderly, and HIV
• hard to tell from eczema

Nail features:

• pitting
• onycholysis (lifting off bed)
• subungal hyperkeratosis
• beaus lines (horizontal across nail)

Psoriatic arthritis

Question 5

Differential diagnoses when considering psoriasis?

Answer 5

• dermatitis / eczema (discoid or seborrheic )
• lichen planus
• Pityriasis rosea (esp guttate psoriasis)
• 2nd stage of syphilis
• reiter’s syndrome (esp palmoplanar psoriasis)
• discoid lupus
• syphilis

Question 6

Precipitating factors for psoriasis?

Answer 6

• trauma (Koebner’s phenomena)
• infection
• drugs: beta-blockers, lithium, antimalarials, NSAIDs, ACEi
• stress
• sunlight
• puberty
• menopause
• alcohol
• obesity
• smoking

Question 7

Disorders associated with Psoriasis?

Answer 7

• psoriatic arthritis (within 10 years of derm, also ank spond)
• IBD
• uveitis
• coeliac disease
• metabolic syndrome (T2DM, HTN, high lipids, gout, CVD)

Question 8

Management of psoriasis?

Answer 8

LIFESTYLE
- minimise risk factors (smoking, alcohol, weight, avoid sun, stress)

TOPICAL:
- emollients

• CORTICOSTEROIDS are mainstay
• prescribe with VIT D analogue
• potent eg betamethasone 0.1% (betnovate)
• combined with Vit D eg daivobet or enstillar foam
• hydrocortisone for face
• Vit D analogues (Calcipotriol, tacalcitol, calcitriol)
• decrease cell proliferation
• can cause skin irritation and hypercalcaemia
• coal TAR preparations
• inhibit DNA synthesis
• smelly, messy
• good for scalp psoriasis
• dithranol (anthralin, decrease cell proliferation, irritates neighbouring skin, stains clothes)
• keratolytics (salicylic acid)
• retinoids (tazarotene)

SYSTEMIC
only in secondary care

• UVB (for classic and guttate, narrow band has low risk of burning)
• PUVA (second line, gives more longterm damage and cancer risk, use with retinoids)
• retinoids
• acitretin
• effect after 4-6 weeks, use for <6 months
• teratogenic for up to 3 years
• dry mucous membranes and hepatoxicity
• immunosuppressants
• methotrexate, also cyclosporin, azathioprine, hydroxurea
• when above have failed
• biologics
• etanercept, adalimumab, infliximab

Question 9

Prognosis of psoriasis?

Answer 9

• variable course
• often relapses
• FHx and early onset is worse prognosis
• over use of steroids can cause pustular flares