Normally, skin cells that form in the deepest layers of your skin make their way to the surface of your skin. They then flake off and are replaced with new skin cells. This takes about a month.
An example of plaque psoriasis on knees
However, in people with psoriasis, the immune system sends signals that make skin cells grow faster than normal. Cells move to the surface of the skin in about four days. Since they move so quickly, they don't have time to fully mature and flake off. In plaque psoriasis, which is the most common type of psoriasis, the cells collect on the skin’s surface, forming raised, red patches known as plaques. They often have silvery scales.
While plaque psoriasis is the most common, there are other types of psoriasis that can affect different areas of the body and appear in a variety of forms. Symptoms may appear on any part of your body, including your hands, feet, scalp, and nails. Some people may also feel pain in their joints, stiffness in the morning, or tiredness. If you have any of these joint symptoms, you may have a related condition called psoriatic arthritis.
See pictures of psoriasis
If you have psoriasis, you're not alone. Up to 7.5 million adults in the United States have psoriasis. It affects men and women at equal rates, and it affects people of all ages. Sign up for emails to learn more about psoriasis and a treatment option.