What is psoriasis?

Updated: Mar 17, 2021
  • Author: Jacquiline Habashy, DO, MSc; Chief Editor: William D James, MD  more...
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Answer

Psoriasis is a complex, chronic, multifactorial, inflammatory disease that involves hyperproliferation of the keratinocytes in the epidermis, with an increase in the epidermal cell turnover rate (see the image below). Environmental, genetic, and immunologic factors appear to play a role. The disease most commonly manifests on the skin of the elbows, knees, scalp, lumbosacral areas, intergluteal clefts, and glans penis. In up to 30% of patients, the joints are also affected.

Treatment is based on surface areas of involvement, body site(s) affected, the presence or absence of arthritis, and the thickness of the plaques and scale.

Plaque psoriasis is raised, roughened, and covered Plaque psoriasis is raised, roughened, and covered with white or silver scale with underlying erythema. Contributed by Randy Park, MD.

See Psoriasis: Manifestations, Management Options, and Mimics, a Critical Images slideshow, to help recognize the major psoriasis subtypes and distinguish them from other skin lesions.


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