Plaque psoriasis is the most common form of the disease and appears as raised, red patches covered with a silvery white buildup of dead skin cells or scale. These patches or plaques most often appear on the scalp, knees, elbows and lower back. They are often itchy and painful, and they can crack and bleed.
If you develop a rash that doesn't go away with an over-the-counter medication, you should consider contacting your doctor. Your doctor will look for raised, red scales with well-defined edges, and will consider how the rash responds to medication before making a diagnosis. Plaque psoriasis is most often found on the outside of knees and elbows, the scalp, the lower back, the face, the palms and soles of feet. When biopsied, psoriasis skin looks thicker and inflamed when compared with eczema.