• Basics

    Psoriasis is a chronic disease in which scaling and inflammation occur on the outer layer of the skin Figure 01. Approximately 2% of the U.S. population has psoriasis. The condition is seen in all age groups but primarily affects adults. Men and women of all races are affected equally. An estimated 150, 000 new cases occur each year.

    Psoriais is categorized as mild, moderate, or severe. Approximately 70% to 80% of people with psoriasis have a mild form of the disease, while 20% to 25% have the moderate-to-severe type. The condition occurs in many forms, the most common of which is plaque psoriasis. Diagnosis can usually be made by the appearance of the lesion. Occasionally, psoriasis may mimic other skin conditions; in these cases a diagnosis is confirmed by a skin biopsy.

    Click to enlarge: Psoriasis

    Figure 01. Psoriasis

    Currently, there is no cure for psoriasis; however, proper treatment can control the disease. Treatments include over-the-counter products and prescription topical medications, shampoos, and ultraviolet (UV) light therapy. In more severe cases, oral medicine is available.

  • Causes

    The scaling and inflammation of psoriasis occur when cells in the outer layer of skin reproduce faster than usual and collect on the skin’s surface. Psoriasis results in patches of thick red or purple skin or plaque beneath silvery scales. In mild cases, the skin plaque covers a small area of the body. In more severe cases, the plaque is found in large areas all over the body.

    A malfunction in the immune system may predispose people to psoriasis. Although no one knows what causes psoriasis, scientists believe that an abnormality in the immune system may cause white blood cells that fight infection (T cells) to trigger inflammation and excessive skin growth. As a result, the inflamed skin sheds excessively every 3 to 4 days.

    Genetic factors predispose people to psoriasis. Psoriasis is more likely to occur in people with family members who have had psoriasis. In one third of the cases, scientists believe that psoriasis is inherited through a gene that causes the disease.

    Certain drugs, weather, and other conditions may cause psoriasis to become worse. Changes in climate, infection, stress, and dry skin may trigger a psoriasis flare-up. For example, winter weather causes the skin to become dry. In addition, sunlight, with its UV rays that are beneficial for psoriasis, is limited during these months. As a result, the condition may become more severe. Medications such as beta-blockers (used for high blood pressure), lithium (used for anxiety), and other medications may also cause a psoriasis outbreak.

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