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Please enter at least one feature (symptom, sign or investigation result) before performing the calculation.
For example, if chest pain and low oxygen saturations were present, but haemoptysis was absent, the features section should look as follows:
To add a feature that is present, start typing and then click the green arrow.
To add the absence of a feature (i.e. a 'negative' finding), start typing then click the red cross.
If you want to remove a feature from the list simply click the grey cross in the box to the right of the feature.
Psoriasis is a common (prevalence around 2%) and chronic skin disorder. It generally presents with red, scaly patches on the skin although it is now recognised that patients with psoriasis are at increased risk of arthritis and cardiovascular disease.
Chronic plaque psoriasis is the most common form of psoriasis seen in clinical practice, accounting for around 80% of presentations.
Incidence: 80.00 cases per 100,000 person-years
Peak incidence: 20-30 years
Sex ratio: 1:1
Multifactorial and not yet fully understood
Associated HLA-B13, -B17, and -Cw6
Strong concordance (70%) in identical twins
Abnormal T cell activity stimulates keratinocyte proliferation
There is increasing evidence this may be mediated by a novel group of T helper cells producing IL-17, designated Th17
These cells seem to be a third T-effector cell subset in addition to Th1 and Th2
It is recognised that psoriasis may be worsened (e.g. Skin trauma, stress), triggered (e.g. Streptococcal infection) or improved (e.g. Sunlight) by environmental factors
Erythematous plaques covered with a silvery-white scale
Typically on the extensor surfaces such as the elbows and knees. Also common on the scalp, trunk, buttocks and periumbilical area
Clear delineation between normal and affected skin
Plaques typically range from 1 to 10 cm in size
If the scale is removed, a red membrane with pinpoint bleeding points may be seen (Auspitz's sign)