Types of psoriasis and where symptoms may occur

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Plaque psoriasis (psoriasis vulgaris)

Plaque psoriasis
presented on the elbow

Psoriasis vulgaris, also known as "plaque psoriasis," is the most common form of psoriasis and affects 80% of people with the disease. Psoriasis vulgaris appears as dry, slightly elevated, red patches, known as plaques, that are covered with a layer of silvery white scale. They may to start out as small bumps that grow together and are typically found on the elbows, knees, scalp, and lower back.

If you have plaque psoriasis, you may also experience changes to your toenails and fingernails—in fact, this occurs in about half of people with psoriasis. Changes to be aware of include: pitting, thickening, discoloration, and loosening of the nail from the nail bed.

The exact cause is unknown: however, researchers believe that hereditary, environment, and the immune system play a role in psoriasis.

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Guttate psoriasis

Guttate psoriasis appears as small, reddish dots. Typically seen on the upper body, legs, and arms, but it can occur on any area. This type of psoriasis commonly appears in adolescence. It often occurs suddenly and sometimes in response to a respiratory infection such as a streptococcal infection ("strep throat").

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Inverse psoriasis

This form of psoriasis appears in the folds of the skin as smooth, red patches without the scale found in plaque psoriasis. It may also be accompanied by itching. Inverse psoriasis may appear in the genital area as well as under the breasts and in the armpits. Due to its location in skin folds where constant friction is present, there is a higher possibility that the lesions will spread to skin that was previously unaffected.

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Pustular psoriasis

Pustular psoriasis appears as small, white, fluid-filled blisters (pustules) surrounded by swollen, reddish skin. It may be localized on the palms and soles of the feet. However, pustular psoriasis can cover the entire body and result in fever, fluid imbalances, and infection. The majority of people with the more generalized form of this psoriasis need to be hospitalized.

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Erythrodermic psoriasis

This form of psoriasis can cover the entire body. The skin appears bright red with extensive fine scaling. It can be quite painful and severe itching may also be present.

Because symptoms are so widespread over the body, this form can be extremely serious. If you have this type of psoriasis, you should see your doctor immediately. The resulting protein, fluid loss, and decrease in body temperature can lead to severe, life-threatening illness and may require hospitalization.

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Palmo-plantar psoriasis

Plaque psoriasis
presented on the palms

Lesions localized to the palms of the hands and the soles of the feet. Typically seen as plaque or pustular psoriasis.

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Scalp

Plaque psoriasis
presented on the scalp

Psoriasis of the scalp affects at least half of all people who have the disease. Lesions appear on the scalp and may spread to the ears, forehead, and the back of the neck. Hair loss may occur. Psoriasis of the scalp can occur without skin changes on the rest of the body.

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Psoriasis of the nails

Psoriasis presented
on the nails

Psoriasis affects the nails in approximately 50% of people with psoriasis. Nail changes vary, but typically include:

• Severe thickening of the nail
• Shallow or deep holes (pits) in the nail
• Nail discoloration, such as yellow-brown
• Nail separation from the nail bed

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Psoriatic arthritis: a related condition

Approximately 30-40% of people with psoriasis actually have psoriatic arthritis, an inflammatory disease that can affect both the skin and the joints. Skin symptoms usually appear before the joint symptoms which typically include swelling of the tendons and ligaments. The fingers and toes may have a sausage-like appearance. Someone with psoriatic arthritis may also experience painful joints, stiffness, fatigue, and a decreased range of motion.

While the skin symptoms and the joint symptoms commonly appear at different times, often years apart, psoriasis is usually diagnosed first. The skin lesions have a distinct, raised border and are bright red and covered in a silvery white scale. Other symptoms may include pitting and ridges in the fingernails and toenails. Both dermatologists (doctors who specialize in skin disease) and rheumatologists (doctors who specialize in joint disease) treat psoriatic arthritis.