1. Moderate to Severe Psoriasis Slideshow Pictures
2. Psoriasis Quiz: Test Your Medical IQ
3. How Much Is Psoriasis Affecting Your Life?

Medical Author:

Gary W. Cole, MD, FAAD

Gary W. Cole, MD, FAAD

Dr. Cole is board certified in dermatology. He obtained his BA degree in bacteriology, his MA degree in microbiology, and his MD at the University of California, Los Angeles. He trained in dermatology at the University of Oregon, where he completed his residency.

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Medical Editor:

William C. Shiel Jr., MD, FACP, FACR

William C. Shiel Jr., MD, FACP, FACR

Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

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In this Article

• Psoriasis facts
• What is psoriasis?
• What causes psoriasis?
• What does psoriasis look like? What are psoriasis symptoms and signs?
• Can psoriasis affect my joints?
• How is psoriasis diagnosed?
• Can psoriasis affect only my nails?
• How many people have psoriasis?
• Is psoriasis curable?
• Is psoriasis contagious?
• Can I transmit the gene for psoriasis to my children?
• What kind of doctor treats psoriasis?
• What is the treatment for psoriasis?
• What creams, lotions, and home remedies are available for psoriasis?
• What oral medications are available for psoriasis?
• What injections or infusions are available for psoriasis?
• What about light therapy for psoriasis?
• Where can I get more information on psoriasis?
• Is there a national psoriasis support group?
• What is my long-term prognosis with psoriasis? What are complications of psoriasis?
• Pictures of Psoriasis - Slideshow
• Take the Psoriasis Quiz
• Psoriasis FAQs
• Patient Comments: Psoriasis - Symptoms
• Patient Comments: Scalp Psoriasis - Treatment
• Patient Comments: Psoriasis - Effective Treatments
• Find a local Dermatologist in your town
• Psoriasis Index

The exact cause remains unknown. There may be a combination of factors, including genetic predisposition and environmental factors. It is common for psoriasis to be found in members of the same family. The immune system is thought to play a major role. Despite research over the past 30 years looking at many triggers, the "master switch" that turns on psoriasis is still a mystery.

Psoriasis appears as red or pink areas of thickened, raised, and scaling skin. It classically affects areas over the elbows, knees, and scalp. Although any body area may be involved, it tends to be more common in areas of trauma, scratching, or abrasions.

Psoriasis may vary in appearance. It most often is small flattened scaly bumps and larger thick plaques of raised red patches of skin.

There are several different types of psoriasis, including psoriasis vulgaris (common type), guttate psoriasis (small, drop-like spots), inverse psoriasis (in the folds like of the underarms, navel, and buttocks), and pustular psoriasis (small pus-filled yellowish blisters). When the palms and the soles are involved, this is known as palmoplantar psoriasis.

Sometimes pulling off one of these small dry white flakes of skin causes a tiny blood spot on the skin. This is medically referred to as a special diagnostic sign in psoriasis called the Auspitz sign.

Genital lesions, especially on the head of the penis, are common. Psoriasis in moist areas like the navel or the area between the buttocks (intergluteal folds) may look like flat red patches. These atypical appearances may be confused with other skin conditions like fungal infections, yeast infections, skin irritation, or bacterial infections.

Finger and toenails often exhibit small pits (pinpoint depressions) and/or larger yellowish-brown separations of the nail bed called "oil spots." Nail psoriasis may be confused with and incorrectly diagnosed as a fungal nail infection.

Scalp psoriasis may look like severe dandruff with dry flakes and red areas of skin. It may be difficult to differentiate between scalp psoriasis and seborrhea dermatitis when only the scalp is involved. However, the treatment is often very similar for both conditions.