Psoriasis

• Ask about articular symptoms of unexplained joint stiffness, pain or swelling, or nail changes - may suggest a diagnosis of psoriatic arthritis

  • Consider using the Psoriasis Epidemiology Screening Tool (PEST) - if scores 3 or more, consider referral to rheumatologist
• Psoriasis is a chronic inflammatory skin condition characterised by clearly defined, red and scaly plaques

  Is classified into several types
• Demographics:

  • Peak onset of 15-25yrs and 50-60yrs
  • Tends to persist lifelong, fluctuating in extent and severity
  • More common in caucasians but may affect people of any ethnicity
  • Commonly have family history of psoriasis
• Distribution:

  • Most commonly the scalp, elbows and knees (extensor surfaces)
  • Flexures
  • Sacral and natal cleft
  • Behind ears
  • Trunk and umbilicus
• Psoriasis is multifactorial. It is classified as an immune-mediated genetic skin disease.
• Clinical features:

  • Symmetrically distributed, red, scaly plaques with well defined edges - scale is typically silvery white, except in skin folds where the plaques often appear shiny with a moist peeling surface
  • Itch is mostly mild but may be severe in some patient - scratching and Lichenification. Painful skin cracks or fissures may occur
  • Can get Koebner phenomenon - new lesions on skin that has been damaged or irritated
  • When clear they may cause post inflammatory hypo or hyperpigmentation
  • Auspitz sign - pinpoint bleeding upon removal of scaly layer
• Certain features of psoriasis can be categorised:

  • Early age of onset <35 yrs (most common) vs late onset >50 yrs
  • Acute (e.g. guttate psoriasis) vis chronic plaque psoriasis
  • Localised vs generalised
  • Thin plaques vs thick plaques
  • Nail involvement vs no nail involvement
• Chronic plaque psoriasis:

  • Most common presentation of psoriasis
  • Persistent and treatment resistant
  • Typical plaque appearance (well demarcated, silvery scale) which can be large >3cm or small <3cm
  • Most often affects elbows, knees, and lower back
  • Ranges from mild to very extensive
• Unstable plaque psoriasis:

  • Rapid extension of existing or new plaques
  • Koebner phenomenon - new plaques at sites of skin injury
  • Induced by infection, stress, drugs or drug withdrawal
• Flexural psoriasis (inverse psoriasis):

  • Affects body folds and genitals
  • Smooth, well-defined patches on erythema (not plaques)
  • Colonised by candida yeasts
• Nail psoriasis:

  • 50% of psoriasis patients will have nail involvement
  • Pitting
  • Onycholysis (distal separation of the nail from nail bed)
  • Yellowing
  • Ridging
  • Associated with inflammatory arthritis
• Erythrodermic psoriasis:

  • Rare but severe form of psoriasis
  • involves over 90% of skin
  • Confluent skin erythema and scalding
  • May occur acutely as the first presentation of psoriasis or may evolve chronically from pre-existing psoriasis
  • Widespread inflammation of the skin can lead to significant fluid loss - dehydration, electrolyte imbalances, peripheral oedema, hypothermia and heart failure
  • Required hospital admission for inpatient management
• Guttate psoriasis:

  • Characterised by multiple small, scaly plaques distributed across the trunk and limbs, which may resemble raindrops
  • Onset is often acute following a streptococcal infection
  • Often responds well to treatment and may clear spontaneously in a matter of months
• Associated conditions:

  • Psoriatic arthritis - affects 10-30% of psoriasis patients, rash usually precedes the arthropathy
  • IBD - affects 5-10% of patients (other cutaneous manifestations - pyoderma gangrenosum, erythema nodosum, erythema multiforme)
  • Coeliac disease
  • Uveitis
  • Metabolic syndrome
  • Non-alcoholic fatty liver disease
• Investigations:

  • Diagnosed clinically - Auspitz sign
  • Use The Psoriasis Area and Severity Index (PASI) tool to assess severity
  • If diagnosis is unclear a skin biopsy can be done
  • Further investigations will be required if a patient with psoriasis has systemic symptoms e.g. erythrodermic psoriasis
• Advise that topical treatments may take several weeks to start to work, and if stopped suddenly there is risk of relapse:

  • Widespread = creams, lotions or gels
  • Thick scale = ointments
  • Hair-bearing area = lotions, solutions, or gels
• Patients with psoriasis should be well-informed about their skin condition and its treatment. Recommendations include:

  • Smoking cessation
  • Safe limits for alcohol consumption
  • Maintaining optimal weight.
• Phototherapy:

  • Psoriasis often responds well to narrow band UVB phototherapy
  • Down-regulates the immune and inflammatory pathways of the skin
  • other forms of phototherapy may be used for non-plaque psoriasis
• Systemic therapies:

  • Oral methotrexate - severe unresponsive psoriasis - slows epidermal cell proliferation
  • Acitretin - oral retinoid that is anti-inflammatory and affects cell proliferation. Potent teratogen.
  • Cyclosporin - calcineurin inhibitor - highly effective but many side effects
  • Biological therapies - treatment resistant psoriasis. Can also treat psoriatic arthritis