Author: Dr Amy Stanway, Registrar, Department of Dermatology, Waikato Hospital, Hamilton, New Zealand, 2004.
Chronic plaque psoriasis is the most common presentation of psoriasis. It presents as small to large, well-demarcated, red, scaly and thickened areas of skin. It most likely to affect elbows, knees, and lower back but may arise on any part of the body.
It tends to be a relatively persistent or chronic pattern of psoriasis that can be improved with treatment but is difficult to clear completely with topical treatments alone. It is characterised by large flat areas (plaques) of psoriasis with a typical silvery scale. These plaques may join together to involve very extensive areas of the skin, particularly on the trunk and limbs. It is often accompanied by scalp and nail psoriasis.
Most cases of plaque psoriasis are described as 'large plaque' or 'small plaque' psoriasis. The plaques may be localised (e.g. to elbows and knees) or generalised (involving scalp, trunk and limbs).
Large plaque psoriasis describes thick, well-demarcated, red plaques with a silvery scale. This type of psoriasis often has an early onset (<40 years) and may be associated with metabolic syndrome. There's often a family history of psoriasis. It can be quite resistant to treatment.
Small plaque psoriasis often presents with numerous lesions a few millimetres to a few centimetres in diameter. The plaques are thinner, pinkish in colour and have a fine scale. They may be well-defined or merge with surrounding skin. Family history is less common. Although it may arise at any age, small plaque psoriasis often arises in those over than 40 years of age. This type of psoriasis often responds well to phototherapy.
Uncommon subtypes or descriptions of chronic plaque psoriasis include:
Patients with chronic plaque psoriasis should be assessed by a dermatologist. Factors considered may include the following:
Patients to be treated with systemic therapy will be asked to undertake screening tests to ensure the medication is safe for them and as a baseline.
Localised or mild chronic plaque psoriasis is usually managed initially with one or more topical agents. The following agents are usually effective for plaque psoriasis:
If plaque psoriasis is too extensive or severe to be effectively managed with topical treatments alone, phototherapy or systemic agents can be used and are usually very effective at improving and even clearing psoriasis; these include:
For more information on these and other treatments, see DermNet's page on treatment for psoriasis.
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