Plaque psoriasis (also called psoriasis vulgaris) is the most common form of psoriasis and usually produces plaques of red, raised, scaly skin affecting mainly your scalp, elbows, and knees. 

Skin lesions, or plaques due to psoriasis most often develop on the scalp, knees, elbows, lower back and feet. They are generally itchy and painful, and can crack and bleed. The size of plaques may vary. They appear as distinct patches or as joined together covering a large surface of your skin.

Psoriasis common sites: It tends to be more common at sites of friction, scratching, or abrasion. These patches or plaques most often occur on the scalp, knees, elbows and lower back.

Psoriasis is a common skin condition that increases the life cycle of skin cells. It causes cells to build up fast on the surface of the skin. The extra skin cells form scales and red patches that causes itching and pain.

Many people with psoriasis develop nail changes, such as pitting, nail bed separation, and changes in color. Psoriasis can affect both fingernails and toenails. The percentage of people with psoriasis who have nail-related symptoms is about 50%.

When the underlying cells reach the skin's surface and die, their volume causes sumptoms to develop in the form of raised, red plaques covered with white scales. Psoriasis generally affects your knees, elbows, and scalp, but it can also affect the torso, palms, and the feet.

Psoriasis on hands and feet can be difficult to treat. If you have an acute psoriasis flare-up on your hands or feet, you should see your doctor immediately.

Psoriasis vulgaris is a psoriatic skin disease which causes skin patches to develop that are typicaly red, itchy, and scaly, as shown in the picture.