Psoriasis is a long-lasting skin disease that causes the skin to
become inflamed. Patches of thick, red skin are covered with
silvery scales. It affects 1-2% of the United States population, or
about 5.5 million people. People with psoriasis may have
discomfort including pain and itching, restricted motion in their
joints, and emotional distress. This reference summary explains
psoriasis. It covers the symptoms, causes, diagnosis, and
treatment options.