psoriasis

psoriasis A reddish, scaly, plaque-like rash that is often located over the surfaces of the elbows, knees, and scalp, and around or in the ears, navel, genitals, or buttocks. Approximately 10 to 15 percent of patients with psoriasis develop joint inflammation (inflammatory arthritis). Psoriasis is caused by the body making too many skin cells as the result of an immune system disturbance in which the body’s T lymphocytes attack healthy skin cells. Treatment options include use of topical steroid creams, use of tar soap preparations, and exposure to ultraviolet light. See also psoriasis, guttate; psoriasis, pustular; psoriatic arthritis.