Psoriasis

Did you know?

• 3 per cent of the global population have psoriasis
• Psoriasis affects 5% of people in the UK
• If both parents have psoriasis, a child has a 50% chance of developing the condition
• Psoriasis usually develops between the age of 11 and 45

Causes of psoriasis

Although the exact cause of psoriasis is not fully understood, the immune system is known to play a part in the condition. Antibodies produced by the immune system help fight germs and viruses. If someone has psoriasis, an antibody called T cells attacks healthy skin triggering an increase in the production of new skin cells and more T cells.

The resulting cycle of skin cell production lasts 5-6 days rather than the normal 28 days leading to a build up of dead skin cells on the surface. Psoriasis is hereditary (runs in families) but how genetics play a part in the cause of the condition is unclear. Certain immune system diseases such as HIV can also cause psoriasis.

Many people with the condition find their symptoms are triggered by factors such as:

• alcohol
• smoking
• a cut or bite to the skin
• sunburn
• stress
• medications (particularly anti-inflammatory drugs such as ibuprofen)

Symptoms of psoriasis

Psoriasis symptoms affect people in different ways. Many people find their psoriasis appears for a couple of weeks and then eases or stops completely only to return again a few months later. Others find their symptoms are longer lasting and never fully disappear.

There are five common types of psoriasis:

Plaque psoriasis – this affects 80% of psoriasis sufferers and is the most common type. Symptoms are red, scaly and dry lesions on the skin covered in silver coloured scales. They typically appear on the elbows, knees, scalp and lower back and can be itchy and sore.

Nail psoriasis – this type of psoriasis affects the nails causing them to grow abnormally and become discoloured. Nails can separate from the nail bed or crumble.

Guttate psoriasis – this causes sores on the chest, arms, legs and scalp and commonly affects children and teenagers. The condition is caused by a streptococci throat infection.

Scalp psoriasis – this causes red patches covered in silver scales which can be itchy and sore and in severe cases may result in hair loss. The whole scalp can be affected but usually the condition appears at the back of the head.

Inverse psoriasis – where the skin folds or creases, smooth red patches can appear with this type of psoriasis. It usually affects the armpits, groin and buttocks or under the breasts. Inverse psoriasis is common in people who are overweight and is made worse in hot weather when the skin sweats causing friction.

Rarer types of psoriasis such as pustular psoriasis causes blisters filled with pus to appear on any part of the body. Psoriatic arthritis affects the joints and connective tissue causing inflammation and swelling usually in the fingers or toes. The rarest type of psoriasis is called erythrodermic psoriasis and affects the whole body with a rash that causes itching and bleeding

Diagnosis of psoriasis

Psoriasis is diagnosed with a physical examination of the skin by your GP. On rare occasions, the GP may take a skin sample to determine the type of psoriasis or rule out other skin disorders. If the GP suspects psoriatic arthritis then you'll be sent for a blood test and referred to a Rheumatologist.

Related terms

Itchy skin
Flaky skin
Scaly skin
Inflammation
Sores
Dermatitis