Psoriasis: differential diagnosis

Differential diagnosis of psoriasis including plaque psoriasis, guttate psoriasis, palmoplantar psoriasis and flexural psoriasis.

Plaque psoriasis
Plaque psoriasis



  • Chronic condition affecting about 2% of the population at any age
  • Any area can be affected, but most commonly extensor surfaces
  • Well-demarcated plaques with thick, silvery scale, which bleed if picked


  • Treatment includes emollients, topical vitamin D derivatives or vitamin D/steroid combinations
  • UV light usually beneficial
  • Severe cases require referral to secondary care
  • Phototherapy can be helpful
  • In severe cases, biological agents can be beneficial

Guttate psoriasis
Guttate psoriasis



  • Typically 1-10mm drop-like salmon-coloured papules with surface scale
  • Monomorphic appearance, starts on torso before spreading to limbs
  • Acute onset usually follows URTI from group B haemolytic streptococcus
  • Most common in under-30s age group
  • May be seen in association with beta-blockers and lithium
  • Biopsy can aid diagnosis


  • Usually self-limiting, resolves in weeks to months. Emollients can help
  • May progress to plaque psoriasis
  • In severe cases, phototherapy can be beneficial

Palmoplantar psoriasis
Palmoplantar psoriasis



  • Thought to be a disorder of eccrine sweat glands
  • Affects palms and soles, although 10-20% have psoriasis elsewhere
  • Rarely occurs in children. More common in women than men
  • More common in smokers
  • Differential diagnoses include fungal infections


  • No known cure. If a smoker, advise on cessation
  • Regular application of emollients will help
  • Treatments include topical steroids, acitretin, psoralen plus UVA light
  • In severe cases, biological agents can be beneficial

Flexural psoriasis
Flexural psoriasis



  • Common condition affects armpits, groin, submammary folds, umbilicus
  • Scale usually absent and skin looks red, shiny and smooth
  • Borders usually well demarcated
  • Psoriasis may also be present in non-flexural areas
  • Secondary infections common


  • Treatment includes emollients and topical steroids
  • Vitamin D analogues helpful but may be poorly tolerated due to irritation
  • Topical calcineurin inhibitors are an alternative to steroids
  • Phototherapy is relatively ineffective in most cases

Dr Nigel Stollery is a GP in Leicestershire

Take a test on this article and claim your certificate on MIMS Learning

Have you registered with us yet?

Register now to enjoy more articles and free email bulletins


Already registered?

Sign in