Plaque psoriasis is a common chronic autoimmune condition affecting the skin (autoimmune conditions occur when the bodies immune system attacks itself, this usually occurs after a triggering event). The condition is characterised by raised patches of skin called plaques, these plaques are usually red, pink or purple with an overlying silvery-white scale caused by an accumulation of dead skin. The patches usually occur on the elbows, knees, scalp or back. Individuals with psoriasis usually complain of itchiness and excessive dead, flaky skin.
People who develop plaque psoriasis will usually have a genetic predisposition to developing the condition however environmental factors can both trigger and exacerbate the process. The condition beings with a triggering event usually localised trauma or infection, this leads to the activation of inflammatory cells in the skin. These inflammatory cells secrete chemicals stimulating skin cells to rapidly replicate reducing skin cell lifespan from 28-30 days to 3-5 days. The shortened skin lifespan leads to an accumulation of dead skin cells which further stimulates local inflammation. It is believed that individuals who develop psoriasis have genetic mutations which compromise the skins barrier function, increasing the susceptibility to damage, and also have gene mutations which compromise the body’s ability to suppress its immune response.
The principles of psoriasis treatment are to suppress inflammation and to normalise skin-cell replication.
Topical (cream-based) steroids (anti-inflammatories) are common first-line treatments that work by reducing skin inflammation, subsequently diminishing skin-cell turnover. Other topical treatments include substances similar to vitamin-D which work by normalising skin cell turnover.
Exposure to UV light is also an effective treatment which works by damaging skin cell DNA inhibiting cell replication and by suppressing the immune cell function. UV therapy, however, needs to be used in a controlled manner as UV light exposure can cause significant skin damage and lead to skin cancers. Oral/tablet medicines are also available for the treatment of severe or stubborn cases.