Diagnosis and management of psoriasis and psoriatic arthritis in adults: summary of SIGN guidance

BMJ 2010; 341 doi: (Published 29 October 2010) Cite this as: BMJ 2010;341:c5623
  1. A D Burden, consultant dermatologist1,
  2. M Hilton Boon, programme manager2,
  3. J Leman, consultant dermatologist3,
  4. H Wilson, consultant rheumatologist4,
  5. R Richmond, consultant in rheumatology5,
  6. A D Ormerod, reader in dermatology6, honorary consultant dermatologist7
  7. on behalf of the Guideline Development Group
  8. on behalf of the Guideline Development Group
  1. 1Alan Lyell Centre for Dermatology, Western Infirmary, Glasgow, UK
  2. 2Scottish Intercollegiate Guidelines Network (SIGN), Glasgow
  3. 3Western Infirmary, Glasgow
  4. 4Stobhill Hospital, Glasgow
  5. 5Borders General Hospital, Melrose, UK
  6. 6Department of Applied Medicine, University of Aberdeen, Aberdeen, UK
  7. 7Aberdeen Royal Infirmary, Aberdeen
  1. Correspondence to: M Hilton Boon michele.hiltonboon{at}

The degree of disability and negative impact on quality of life caused by psoriasis and psoriatic arthritis are comparable to those of ischaemic heart disease, diabetes, depression, and cancer.1 Severe psoriasis and psoriatic arthritis are associated with an increased risk of conditions such as cardiovascular disease, diabetes, and depression.2 3 4 5 Psoriatic arthritis is underdiagnosed; about a fifth of patients with psoriasis also have psoriatic arthritis.6 The management of patients with both conditions may be particularly challenging and require close collaboration among several specialties. This article summarises the most recent recommendations from the Scottish Intercollegiate Guidelines Network (SIGN) on the diagnosis and management of psoriasis and psoriatic arthritis in adults.7


SIGN recommendations are based on systematic reviews of best available evidence. The strength of the evidence is graded as A, B, C, or D (fig 1), but the grading does not reflect the clinical importance of the recommendations. Recommended best practice (“good practice points”), based on the clinical experience of the guideline development group, is also indicated (as GPP).

Fig 1 Explanation of SIGN grades of recommendations

Diagnosis and assessment in primary care

  • Diagnose chronic plaque psoriasis (psoriasis vulgaris) on the basis of well demarcated bright red plaques covered by adherent silvery white scales affecting any body site, often symmetrically, especially the scalp and extensor surfaces of limbs. The differential diagnosis includes eczema, tinea, lichen planus, and lupus erythematosus (GPP).

  • Diagnose guttate psoriasis (fig 2) on the basis of the development over a period of one to seven days of multiple small papules of psoriasis over wide areas of the body. The differential diagnosis includes pityriasis rosea, viral exanthems, and drug eruptions (GPP).

  • Generalised pustular psoriasis (fig 3) is rare and is characterised by the development of numerous sterile non-follicular pustules within plaques of psoriasis or on red …

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