Psoriasis

Psoriasis (so-RY-uh-sis) is a long-lasting skin disease that causes patches of skin to become red, thickened, and covered with silvery-looking flakes.

When the American writer John Updike (1932–2009) wrote a book about his own life, titled Self-Consciousness, he spent a whole chapter describing his personal battle with the chronic * skin disease psoriasis. Updike called the chapter “At War with My Skin.” The word psoriasis comes from the Greek verb meaning “to itch.” The disease causes patches of skin to become red, thickened, itchy, and covered with silvery flakes. The disease may also affect the fingernails and toenails or the soft tissues of the genitals and the lining of the mouth. Studies show that between 10 and 30 percent of people with psoriasis also develop joint inflammation (psoriatic arthritis).

Some research suggests that psoriasis may be due to a problem with the immune system * . The immune system includes a type of white blood cell called the T cell. Researchers have speculated that people with psoriasis may have a problem with the immune system that causes it to make too many T cells in the skin.

People with psoriasis often notice that at times their skin gets worse, and then gets better. The bad times, known as flare-ups or flares, may be triggered by such conditions as climate changes, infections, stress, dry skin, and certain medicines. Flare-ups may also occur after the skin has been cut, scratched, rubbed, or sunburned. People whose relatives have psoriasis are more likely to have it. Scientists have studied families with psoriasis to try to find genes linked to the disease. A number of different genes have been linked to psoriasis, but it was unclear, as of 2016, how these genes work together to cause the disease.

Psoriasis causes patches of red, thickened skin with silvery flakes, most often on the scalp, elbows, knees, lower back, face, inside of the hands, and bottom of the feet. These patches are sometimes known as plaques (PLAKS). They may itch or burn, and the skin may crack. The disease can also affect the fingernails, toenails, and the moist tissues that line the mouth and genitals. Those who develop psoriatic arthritis (so-ree-AT-ik ar-THRY-tis) experience pain, swelling, and stiffness of the joints (the places where bones meet).

A doctor usually identifies psoriasis by looking carefully at the skin, scalp, and nails. If the problem is psoriasis, the doctor can try various treatments that may clear up the skin for a time. There was, however, no permanent cure for psoriasis as of 2016. The choice of treatment depends on a person's age, health, and lifestyle, and the severity of the psoriasis. No single treatment works for everyone, but most people can be helped. The following are some of the treatment choices.

Many people with psoriasis find that it helps to keep the skin moist. Lotions, oils, and petroleum jelly (such as Vaseline) are often useful for this purpose. During the winter months, heaters can make the air inside a house quite dry, so it may help to run a humidifier (hu-MID-i-fy-er), a machine that puts moisture back into the air. It is also a good idea for people with psoriasis to avoid getting harsh soaps and chemicals on their skin. In addition, they should protect their skin from injury by taking such steps as not wearing overly tight clothes or shaving with a dull razor.

See also Autoimmune Disorders: Overview • Skin Conditions: Overview

* chronic (KRAH-nik) means lasting a long time or recurring frequently.

* immune system (im-YOON SIStem) is the system of the body composed of specialized cells and the substances they produce that help protect the body against disease-causing germs.