Psoriasis is a common, chronic skin disorder that can affect any part of the body. It is characterized by raised, inflamed lesions that join together to form plaques (patches) with distinct borders that are covered with flaky scales. It is not contagious, but is related to hereditary factors. Psoriasis is highly variable and often quite different from person to person. It may be no more than a minor cosmetic problem or quite severe, but most cases are mild to moderate. There may be many remissions and flares, but prolonged remissions are rare. In addition, the patient’s quality of life may be affected.

Most cases of psoriasis are not life-threatening, but severe cases may lead to secondary infections, some of which may become serious. Severe psoriasis may also lead to fluid loss and poor circulation (blood flow). In addition, patients undergoing treatments for severe psoriasis may experience adverse side effects from the drugs used.

The skin changes that characterize psoriasis are due to the rapid turnover of cells in the epidermis. Normal skin cells mature in about one month. In psoriasis, new cells are produced, grow to maturity and die quickly, severely reducing the cell cycle to about four days. Because this is believed to be caused by a faulty immune system, psoriasis is considered an autoimmune disease.

According to the National Institute of Arthritis and Musculoskeletal and Skin Diseases, about 2 percent of all people in the United States have psoriasis. Although the onset of the disease can occur any time in life, there are two peaks: from 20 to 30 years and from 50 to 60 years of age. In most cases, onset occurs before the age of 40. Men and women are equally affected by the disease, but onset is typically earlier in women. It also occurs earlier in patients with a family history of psoriasis. Psoriasis is more common in Caucasians than in other races.