What Is Chronic Plaque Psoriasis?

Woman scratching her arm
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Chronic plaque psoriasis is the most common type of psoriasis. It occurs in 0.6 percent to 4.8 percent of people in the United States, and it is slightly more common in men. These psoriasis lesions are the best examples of plaques, hence the name.

Characteristics of Plaque Psoriasis

Plaque psoriasis lesions are fairly typical and have the following features:

  • The outline of the lesion is either circular, oval, or polycircular (overlapping circles)
  • The borders of the lesion are well-defined
  • There are thick, silvery-white scales on top of a red, irritated base
  • If the scale is scraped off, tiny bleeding spots appear underneath (Auspitz sign)
  • Areas most often involved include the knees, elbows, scalp, and just above the buttocks
  • Once a plaque forms it may get bigger, but when it reaches a certain size it stops growing and stays the same size for months to years without treatment.

Pictures of Plaque Psoriasis

Diagnosis

Plaque psoriasis is diagnosed mainly by its typical appearance. It can sometimes be confused with ringworm or eczema, and when the diagnosis is uncertain, a skin biopsy can be done to diagnose a lesion.

Sources:

Habif, Thomas. "Psoriasis." Clinical Dermatology, 4th Edition. Ed. Thomas Habif, MD. New York: Mosby, 2004. 209-39.

Luba, Kelly, and Daniel Stulberg. "Chronic Plaque Psoriasis." American Family Physician. 73(2006):636-44.

Schon, Michael, and W.-Henning Boehncke. "Psoriasis." The New England Journal of Medicine 352(2005): 1899-912.

Smith, Catherine, and JNWN Barker. "Psoriasis and its management." British Medical Journal 333(2006): 380-4.

van de Kerkhof, Peter. "Psoriasis." Dermatology. Ed. Jean Bolognia. New York: Mosby, 2003: 531-5. 125-37

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