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Plaque Psoriasis, Eruptive Psoriasis, Pustular Psoriasis

What is Psoriasis?

Psoriasis is a common skin disease affecting one to two percent of the population. It is a chronic condition characterized by thickened, raised patches (plaques) of inflamed, red skin, often covered by silvery scales (papulosquamous lesion). In psoriasis, new skin cells are produced about ten times faster than normal, but the rate at which old cells are shed remains unchanged. As a result, the live cells stack up, becoming thickened patches covered by the dead, flaking skin.

Although the exact cause of psoriasis is unknown, heredity is a factor as two-thirds of the individuals with psoriasis have a close family member who is also affected. Psoriasis may begin at any age, including infants and the elderly, but usually first appears between the ages of ten and thirty. Less common in blacks and Asians, psoriasis affects men and women equally.

How is it diagnosed?

History: Psoriasis most commonly appears on knees, elbows, and scalp, but can also occur in the genital area, on the breasts, in the armpits, or on the hands and feet. Most individuals have stable, slowly growing plaques. The patches may be itchy or sore. The skin eruptions may be accompanied by painful swelling and stiffness in the joints (psoriatic arthritis) in ten percent of the cases of psoriasis. Psoriasis can be an intermittent condition with varying degrees of severity. Attacks may be triggered by such things as emotional stress, skin injury, and physical illness. It can develop into a serious condition in infants and the elderly if it is extensive or neglected.

Physical exam: Psoriasis can appear in different forms including plaque and eruptive psoriasis. The skin changes commonly seen with plaque psoriasis include dark pink, raised patches of skin covered by silver scales that appear on the trunk, scalp, and limbs (especially the elbows and knees). In some severe cases, painful pustules, cracks, or blisters may appear. Finger and toe nails may become pitted, thickened, or separated from their beds in about half the cases.

Eruptive psoriasis occurs most frequently in children and young adults, with numerous small patches developing rapidly over a wide area of skin after a bout of strep throat.

In pustular psoriasis, small pimple-like lesions (pustules) can cover the entire body, or be confined to isolated locations (such as the palms and soles).

Tests: If a certain diagnosis cannot be made from the history and physical exam, further testing would include a skin scraping examined under a microscope to check for other causes of the rash. If necessary, a skin biopsy will show the characteristic changes of psoriasis. Since ten to twenty percent of the cases are associated with arthritis, blood tests for other diseases that can cause arthritis are usually done.

How is Psoriasis treated?

Mild episodes of psoriasis may be helped by moderate exposure to sunlight or an ultraviolet lamp (actinotherapy). Arthritic symptoms are treated with nonsteroidal anti-inflammatory drugs. Moderate episodes are usually treated with an ointment that contains coal tar or a synthetic hydrocarbon combined with ultraviolet light in the sunburn (UVB) range. This treatment, when applied over a period of a month, can produce remissions of one year or longer.

If the psoriasis fails to respond to these treatments, then a type of phototherapy (PUVA) is used. It involves drugs taken by mouth before strong ultraviolet light (UVA) is directed at the lesions. When repeated two to three times a week, the psoriasis clears in 90% of the individuals within two months.

Psoriasis Medication


Prograf (Tacrolimus), Flonase (Fluticasone topical), Topamax (Topiramate), Arava (Leflunomide), Rheumatrex (Methotrexate)

What might complicate it?

Psoriasis can be accompanied by painful swelling and stiffness of the joints called psoriatic arthritis.

Predicted outcome

Psoriasis is considered a chronic condition, with no permanent cure. However, individual episodes can be relieved with appropriate treatment.


The skin lesions seen in psoriasis are seldom mistaken for other skin diseases. Secondary syphilis can cause lesions on the palms and soles, but a simple blood test can confirm this diagnosis. Acute and chronic pityriasis lichenoides looks like psoriasis but does not affect the typical sites of knees, elbows and scalp.

Appropriate specialists

Dermatologist and rheumatologist.

Notify your physician if

  • You or a family member has symptoms of psoriasis, or symptoms recur after treatment.
  • During an outbreak, pustules erupt on the skin, accompanied by fever, muscle aches and fatigue.

Last updated 6 April 2018