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How is Psoriasis Diagnosed?

February 9, 2008 2:00 PM

How Is Psoriasis Diagnosed?

Occasionally, doctors may find it difficult to diagnose psoriasis, because it often looks like other skin diseases. It may be necessary to confirm a diagnosis by examining a small skin sample under a microscope. There are several forms of psoriasis. Some of these include:
  • Plaque psoriasis--Skin lesions are red at the base and covered by silvery scales.
  • Guttate psoriasis--Small, drop-shaped lesions appear on the trunk, limbs, and scalp. Guttate psoriasis is most often triggered by upper respiratory infections (for example, a sore throat caused by streptococcal bacteria).
  • Pustular psoriasis--Blisters of noninfectious pus appear on the skin. Attacks of pustular psoriasis may be triggered by medications, infections, stress, or exposure to certain chemicals.
  • Inverse psoriasis--Smooth, red patches occur in the folds of the skin near the genitals, under the breasts, or in the armpits. The symptoms may be worsened by friction and sweating.
  • Erythrodermic psoriasis--Widespread reddening and scaling of the skin may be a reaction to severe sunburn or to taking corticosteroids (cortisone) or other medications. It can also be caused by a prolonged period of increased activity of psoriasis that is poorly controlled.
  • Psoriatic arthritis--Joint inflammation that produces symptoms of arthritis in patients who have or will develop psoriasis.