Psoriasis is a chronic skin disease that affects more than 5 million Americans. It can occur at any age, including infancy and childhood. Psoriasis is not contagious. The rash of psoriasis is often found on the knees, elbows, scalp, hands and feet, although it can occur anywhere on the skin.
Psoriasis can be limited to a few lesions or it can involve larger areas of skin. It affects each person differently. Some people with psoriasis may also develop arthritis, which results in painful or swollen joints.