Psoriasis is a chronic, non-contagious autoimmune disease that affects the skin and joints. It commonly causes red, scaly patches to appear on the skin, although some patients have no dermatological symptoms. The scaly patches caused by psoriasis, called psoriatic plaques, are areas of inflammation and excessive skin production. Skin rapidly accumulates at these sites and takes on a silvery-white appearance. Plaques frequently occur on the skin of the elbows and knees, but can affect any area including the scalp and genitals.

Complications of Psoriasis

• Psoriatic arthritis
  Between 10% and 20% of people with psoriasis develop psoriatic arthritis, which causes tenderness, pain and swelling in the joints and connective tissue with associated stiffness. It commonly affects the ends of the fingers and toes.
• Psychological complications
  Due to the unpleasant effects psoriasis can have on physical appearance, feelings of low self-esteem and anxiety are common among people living with this condition. These feelings can then trigger depression, especially if the psoriasis worsens.
• Nail deformities

Causes of Psoriasis

The exact cause of psoriasis is unknown but it is known that your immune system plays a part. Your immune system is your body's defense against disease - it produces proteins (antibodies) that attack germs and viruses. For some reason, if you have psoriasis, one of these antibodies called T cells start attacking healthy skin cells by mistake. This triggers other immune responses that cause an increase in the production of new skin cells and also T cells. This results in a cycle of skin cell production becoming faster and faster - skin cells are created and then die in the space of five to six days, rather than the normal 28 days. The dead skin cells then build on the surface of your skin in thick scaly patches.

Signs & Symptoms of Psoriasis

The symptoms of psoriasis vary from person to person.

Most people find that their psoriasis goes through cycles - it causes problems for a few weeks or months, and then the symptoms ease or stop. There are several different types of psoriasis. Typically, people have only one form of psoriasis at a time, although sometimes two different types can occur together. One type may change to another type, or one type may become more severe.
Common types of psoriasis are:

• Plaque psoriasis - the most common form of psoriasis. Around 80% of people with psoriasis have plaque psoriasis. Its symptoms are dry, red skin lesions - known as plaques - that are covered in silver scales. They normally appear on your elbows, knees, scalp and lower back but can appear anywhere on your body. The plaques are normally itchy, sore, or both. In severe cases the skin around your joints may crack and bleed.
• Nail psoriasis - this affects your nails, causing them to pit, become discoloured and grow abnormally. Often nails can become loose and separate from your nail bed. In some severe cases, your nails may crumble.
• Guttate psoriasis - this normally occurs following a throat infection (streptococci) and is more common among children and teenagers. This causes small (less than 1cm - one third of an inch) water-drop-shaped sores on your chest, arms, legs and scalp. There is a good chance that guttate psoriasis will disappear completely, but some young people go on to develop plaque psoriasis.
• Scalp psoriasis - this normally affects the back of your head, but it can occur in other parts of your scalp, or on the whole scalp. This causes red patches of skin covered in thick silvery-white scales. Some people find scalp psoriasis extremely itchy, while others have no discomfort. In extreme cases it can cause hair loss, though permanent balding is very rare.
• Inverse psoriasis - this affects areas of the skin that are in folds or creases, such as the armpits, groin, and the skin between the buttocks and under the breasts. This can cause large smooth red patches to occur in some or all of these areas. Inverse psoriasis is made worse by friction and sweating, so it can be particularly uncomfortable in hot weather. Inverse psoriasis is more common in overweight people.
• Pustular psoriasis- There is rarer types of psoriasis known as pustular psoriasis. These cause pus-filled blisters (pustules) to appear on your skin.

Diagnosis of Psoriasis

• There is no blood test for psoriasis. Usually your doctor will make the diagnosis from the appearance of your affected skin. Rarely, a sample of skin scrapings or a small sample of skin will be sent to the laboratory for examination under a microscope.
  If your doctor suspects you have psoriatic arthritis (see complications), you should be referred to a rheumatologist, who specializes in arthritis.
• Blood tests may be taken to rule out other conditions and X-rays of the affected joints may be taken.

Treatments of Psoriasis

Treatments fall into three categories:

• topical - creams and ointments are applied to your skin,
• phototherapy - your skin is exposed to certain types of light, and
• oral and injected medication - medicine is used to reduce the production of your skin cells.

Prevention of Psoriasis

• Keep skin lubricated. Oils, creams and petroleum jelly preparations are suggested.
• Use a humidifier in the home.
• Get out in the sun. Be careful not to burn. Exposing only the areas of your body with active psoriasis may be optimal.
• Bathing in hot water may help reduce scaling.
• Use mild soaps or soap-free cleaners. Mild soaps such as Nivea Cream, Neutrogena Dry Skin, Dove, or Baby Johnsons are recommended.
• Minimize stress.
• Protect against skin injuries and skin infections.

When to seek Medical Advice

You should see your doctor or health care practitioner if you have symptoms of psoriasis, such as red raised patches of skin with silvery scales, and do not feel comfortable with how your skin looks or feels. Psoriasis is usually a mild inconvenience to most people. However, for others, it may be disabling or painful. The doctor can prescribe treatments that help. If symptoms are treated when they first appear, the condition will usually not progress.