Psoriasis

The Five Types of Psoriasis

A number of different forms of psoriasis can affect the skin. The five main types are plaque, guttate, inverse, pustular and erythrodermic. Here's an explanation of each of these types.

Plaque: About 80 percent of people with psoriasis have plaque psoriasis. The medical term for this form is psoriasis vulgaris, meaning "ordinary psoriasis." It appears as red, inflamed lesions—also called "plaques"—covered in a silvery-white scale. The scale is composed of dead skin cells that have made their way to the skin's surface. Skin affected by plaques is usually dry, but it also can be painful, itchy and may crack. Lesions may appear anywhere on the skin, but they are most commonly found on the elbows, knees, scalp and lower back.

Guttate: Guttate psoriasis appears as small, red spots on the skin. The spots are not usually as thick and dry as the lesions found in plaque psoriasis. Common triggers for the disease are strep throat and upper respiratory infections, so anyone experiencing guttate psoriasis for the first time should have a throat culture.

Guttate psoriasis often occurs in childhood; nearly a third of people with the condition have their first episode before the age of 20. In some cases, the spots go away on their own; in others, they merge into the larger lesions of plaque psoriasis. Remission is permanent in some cases; in other cases, the condition re-emerges as either guttate or plaque psoriasis.

Inverse: Inverse psoriasis affects areas of the body where the skin bends or touches other skin, such as the groin, the armpit, behind the ear, under the breasts and buttocks and beneath the foreskin of an uncircumcised penis. The plaques are deep red in color, smooth and shiny with a moist, white surface. Infection, friction and heat can contribute to the formation of lesions.

Pustular: In pustular psoriasis, white, pus-filled blisters form over reddened skin. This is a relatively uncommon form of psoriasis, accounting for fewer than five percent of cases. It can affect specific areas of the body, such as the hands and feet, or it can cover large areas of skin. Pustular psoriasis can be the first sign of psoriasis, or it can develop in people who have plaque psoriasis. It is unclear what causes pustular psoriasis, but it may be triggered by certain medications, overexposure to ultraviolet light, pregnancy, corticosteroids, infections and stress.

There are several subtypes of pustular psoriasis. One of them, Von Zumbusch pustular psoriasis, is characterized by widespread eruptions of pustules that dry and peel off after one or two days. This type of psoriasis requires immediate medical attention because it leaves the skin unable to maintain proper fluid balance and fight infections. In palmo-plantar pustulosis, small pustules form on the palms of the hands and soles of the feet. There is also a rare form of psoriasis—called acropustulosis—that affects the ends of the fingers and sometimes the toes.

Erythrodermic: In erythrodermic psoriasis, large areas of the skin become severely inflamed and red. The condition often causes pain and extreme itching. It usually occurs in people who have unstable plaque psoriasis, in which the lesions are not clearly defined. It also may occur in combination with Von Zumbusch pustular psoriasis. Anyone experiencing a flare-up of erythrodermic psoriasis should seek immediate medical attention.

Questions to ask your doctor:

1. What type of psoriasis do I have?
   
2. What can I do to reduce the risk of developing another form of the disease?
   
3. Under what circumstances should I go to a hospital or make an emergency appointment to see you?