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

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). • Generalised pustular psoriasis (fig 2) is rare and is characterised by the development of numerous sterile non-follicular pustules within plaques of psoriasis or on red tender skin. This may occur acutely and be associated with fever. The differential diagnosis includes pyogenic infection, vasculitis, and drug eruptions (GPP). GUIDELINES Diagnosis and management of psoriasis and psoriatic arthritis in adults: summary of SIGN guidance