Plaque psoriasis is the most common form of psoriasis and appears as raised, red patches covered with a silvery white buildup of dead skin cells or scale, often appearing on the skin of the knees, elbows, scalp and lower back.
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.
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, the cells collect on the skin’s surface, forming raised, red patches known as plaques. They often have silvery scales.