Psoriasis

Psoriasis a skin condition that causes red, flaky, crusty patches of skin covered with silvery scales.

Skin cells have a life cycle. Your body produces new cells in your deepest skin level. These skin cells gradually move up through the layers of your skin until they reach the outermost level. Then they die and flake off. The whole process normally takes around 21 to 28 days.

In psoriasis, this process speeds up and only takes two to six days. As a result, cells that are not fully mature build up rapidly on the surface of the skin, causing red, flaky, crusty patches covered with silvery scales. These patches are easily shed. It can occur on any part of the body, but is most common on the elbows, knees, lower back and scalp. It can cause itching and burning.

The condition is not infectious and most people are affected only in small patches on their body.

The severity of psoriasis varies greatly from person to person. For some people it is just a minor irritation, but for others it has a major impact on their quality of life.

The severity of the psoriasis is also dependent on both genetic factors and environmental factors such as stress, smoking and drinking alcohol. Changes in the immune system are strongly linked to the severity of psoriasis. 

Psoriasis is a long-lasting condition (chronic) that can return at any time. There may be times when you have no symptoms or very mild symptoms followed by times when the symptoms are severe.

There is no cure for psoriasis, but there is a range of treatments that can improve your symptoms and the appearance of the affected skin patches.

It is estimated that 3 people in every 20 with AS will also have psoriasis. IL23R is a gene that encodes a molecular switch involved in the healthy maintenance of a type of immune cell known as a Th17 lymphocyte. IL23R is also associated with psoriasis.

This could be psoriatic arthritis or AS and psoriasis. Telling the difference between these two is difficult and involves a specialist in the area (rheumatologist). 

Generally, a person with psoriatic arthritis has:

  • more neck arthritis
  • the inflammation may be more on one side of the body than the other because one of the two joints in the pelvis called the sacoiliac joints are affected
  • the bony growths coming from the vertebrae in the spine (as seen on x ray) may be more large and coarse

A person with AS and psoriasis generally has:

  • more spinal arthritis 
  • inflammation symmetrically (ie on both sides of the pelvis affecting both sacroiliac joints)
  • finer bony growths on the vertebrae (as seen on x ray)

For more information on psoriasis please contact The Psoriasis Association. You can find their website at www.psoriasis-association.org.uk.

Last reviewd: May 2011