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Psoriasis is a chronic, inflammatory skin disease characterised by keratinocyte hyperproliferation. The most common type is plaque psoriasis, which causes erythematous raised plaques on extensor surfaces.

Suggested approach to psoriasis osce station


  • Dermatological skin exam
    • Skin
    • Scalp 
    • Ears 
  • Nails
  • Hand joints

Describing lesions

  • Plaques
    • ‘There are multiple well-demarcated, raised erythematous plaques over the extensor surfaces.’
    • ‘These range in size from 1-6cm.’
    • ‘There is scaling across the surface of these lesions, but no other secondary features.’
    • ‘These lesions are consistent with chronic plaque type psoriasis.’
  • Nails
    • ‘There is also evidence of pitting, subungual hyperkeratosis, onycholysis and Beau lines on the finger nails.’
    • ‘These are characteristic psoriatic nail changes.’
  • Joints
    • ‘I can also see a symmetrical polyarthropathy of the distal inter-phalangeal joints with active synovitis.’
    • ‘This could be evidence of psoriatic arthritis.’

Differential diagnosis

  • Other types of psoriasis
  • Eczema

Types of psoriasis

Chronic plaqueMost common and described here
GuttateRaindrop lesions
SeborrhoeicLesions around nose and ears
FlexuralFlexural surfaces affected
PustularPustular lesions on palms/soles
Erythrodermic>90% of skin affected


  • Multiple HLA subtypes
  • Post-streptococcal guttate psoriasis
  • Medications (β-blockers, antimalarials, lithium)
  • Alcohol 
  • Stress
  • Trauma (Koebner phenomenon)
  • HIV


  • Avoid precipitants
  • Emollients
  • Topical treatments
    • Combination treatments (e.g. Dovobet ointment or Enstilar foam) often used first line
    • Vitamin D analogues, e.g. calcipotriol
    • Topical corticosteroids
    • Coal tar
    • Dithranol
    • Topical retinoids
  • Phototherapy
  • Systemic rheumatological drugs (methotrexate, ciclosporin, infliximab)