The hallmark symptoms of psoriasis, a chronic inflammatory skin disease, are plaques composed of thick, scaly skin. These are typically reddened in appearance with silvery scales. The elbows, knees, and scalp are common sites of involvement, although other areas of skin can be affected as well. The condition can start as a few red bumps on the skin, and in mild cases, small areas of dry skin may be the only symptoms. Itching and burning sensations can be associated with the lesions on the skin. The nails may be affected, and psoriasis of the nails causes ridged, thick, or pitted nails and can ultimately lead to separation of the nails from the nail bed. Symptoms of arthritis, including stiffness, pain, and swelling of the joints, occur in some people with psoriasis. There are different forms of psoriasis that can affect different areas and produce different kinds of skin changes. For example, pustular psoriasis is characterized by blisters filled with pus. Fever, chills, and diarrhea can accompany this type of psoriasis.