Psoriasis
Psoriasis Causes
What Causes Psoriasis?
Psoriasis is a skin disorder driven by the immune system, especially involving a type of white blood cell called a T cell. Normally, T cells help protect the body against infection and disease. In the case of psoriasis, T cells are put into action by mistake and become so active that they trigger other immune responses, which lead to inflammation and to rapid turnover of skin cells. In about one-third of the cases, there is a family history of psoriasis. Researchers have studied a large number of families affected by psoriasis and identified genes linked to the disease. (Genes govern every bodily function and determine the inherited traits passed from parent to child.) People with psoriasis may notice that there are times when their skin worsens, then improves. Conditions that may cause flareups include infections, stress, and changes in climate that dry the skin. Also, certain medicines, including lithium and betablockers, which are prescribed for high blood pressure, may trigger an outbreak or worsen the disease.
Psoriasis Diagnosis
How Is Psoriasis Diagnosed?
Occasionally, doctors may find it difficult to diagnose psoriasis, because it often looks like other skin diseases. It may be necessary to confirm a diagnosis by examining a small skin sample under a microscope. There are several forms of psoriasis. Some of these include:
- Plaque psoriasis – Skin lesions are red at the base and covered by silvery scales.
- Guttate psoriasis – Small, drop-shaped lesions appear on the trunk, limbs, and scalp. Guttate psoriasis is most often triggered by upper respiratory infections (for example, a sore throat caused by streptococcal bacteria).
- Pustular psoriasis – Blisters of noninfectious pus appear on the skin. Attacks of pustular psoriasis may be triggered by medications, infections, stress, or exposure to certain chemicals.
- Inverse psoriasis – Smooth, red patches occur in the folds of the skin near the genitals, under the breasts, or in the armpits. The symptoms may be worsened by friction and sweating.
- Erythrodermic psoriasis – Widespread reddening and scaling of the skin may be a reaction to severe sunburn or to taking corticosteroids (cortisone) or other medications. It can also be caused by a prolonged period of increased activity of psoriasis that is poorly controlled.
- Psoriatic arthritis – Joint inflammation that produces symptoms of arthritis in patients who have or will develop psoriasis.
