Differential diagnoses: Psoriasis

Dr Nigel Stollery compares four types of psoriasis and offers clues for their diagnosis.

Plaque psoriasis

Presentation

  • Chronic condition affecting about 2% of the population
  • Any areas can be affected, but occurs most commonly on extensor surfaces
  • Well-demarcated plaques with thick scale
  • Scales have a silvery surface and bleed if picked
  • Can develop at any age

Management

  • Treatment includes emollients, topical vitamin D derivatives or vitamin D/steroids 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

Presentation

  • Typically 1-10mm diameter 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
  • May be seen in association with beta blockers and lithium
  • Biopsy can aid diagnosis

Management

  • Usually self limiting
  • Resolves over weeks to months
  • Emollients can be helpful
  • May progress to plaque psoriasis
  • In severe cases, phototherapy can be beneficial

Palmoplantar psoriasis

Presentation

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

Management

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

Flexural psoriasis

Presentation

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

Management

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

Dr Stollery is a GP in Kibworth, Leicestershire, and clinical assistant in dermatology at Leicester Royal Infirmary

Have you registered with us yet?

Register now to enjoy more articles and free email bulletins

Register

Already registered?

Sign in

Follow Us:

Just published

GP practices face losses 'in excess of £50,000' as COVID-19 hits income

GP practices face losses 'in excess of £50,000' as COVID-19 hits income

GP practices across England are facing a significant loss of income as COVID-19 dries...

MPs explore GP workload cap and flag damaging impact of intense pressure

MPs explore GP workload cap and flag damaging impact of intense pressure

MPs have raised the prospect of a cap on GP consultations in an investigation into...

GP training: Working remotely as a GP trainee during the pandemic

GP training: Working remotely as a GP trainee during the pandemic

Dr Zoe Brown was in her first year of GP training and pregnant as lockdown began....

GPs warn government off PCN-led test and trace system

GPs warn government off PCN-led test and trace system

GPs have rebuffed suggestions that primary care networks (PCNs) are ‘best placed’...

Map: Three-fold variation in GP practice list size between CCGs

Map: Three-fold variation in GP practice list size between CCGs

The list size of GP practices across England has grown rapidly over the past decade...

Advance decisions to refuse treatment - what GPs need to know

Advance decisions to refuse treatment - what GPs need to know

A recent case has underlined the need for GPs to communicate a patient’s known wishes...