What Is Psoriasis?

Psoriasis is a chronic autoimmune disorder that produces inflamed, raised and red areas of skin or silvery scales. Scientists believe it is most likely caused by abnormally fast-growing and shedding skin cells. There are five main forms of psoriasis:

  • Plaque (discoid) psoriasis: This is the most common form and typically is characterized by patches of raised, red skin covered in a layer of silvery white dead skin cells. It appears on the arms, legs, knees, elbows and scalp.
  • Guttate psoriasis: This is most common in children and features small, pink-red spots. It can be brought on by a strep infection.
  • Inverse (flexural or intertriginous) psoriasis: This produces smooth, shiny red lesions in body folds, such as the groin, under the arm or behind the knee. People who have inverse psoriasis often have another type on other body parts.
  • Pustular psoriasis: This type produces pus-containing blisters surrounded by red skin, especially on the palms of the hands and soles of the feet.
  • Erythrodermic (exfoliative) psoriasis: This rare form produces widespread rash with severe itching and pain. The skin becomes very red and peels off in large segments.

The skin inflammation of psoriasis may also be associated with psoriatic arthritis, a form of inflammatory arthritis that causes joint pain. Nearly 1 in 3 people with psoriasis will develop psoriatic arthritis. Psoriasis is also associated with diabetes, heart disease and depression.

Psoriasis affects men and women equally, and is most likely to begin between the ages of 15 and 35 or between 50 and 69. About one-third of people with psoriasis have a family member with the condition.