Psoriasis Overview

SOURCE: National Psoriasis Foundation (www.psoriasis.org) and
National Institute of Arthritis and Musculoskeletal Skin Diseases
Division of National Institute of Health (http://www.niams.nih.gov).

Overview of Psoriasis and Psoriatic Arthritis

Psoriasis (sore-I-ah-sis) is a common immune-mediated chronic skin disease that
comes in different forms and varying levels of severity. Most researchers now
conclude that it is related to the immune system (psoriasis is often called an
"immune-mediated" disease).

It is not contagious. In general, it is a condition that is frequently found on the
knees, elbows, scalp, hands, feet or lower back. Many treatments are available to
help manage its symptoms. More than 4.5 million adults in the United States have
it.

The average age of diagnosis is 28, and psoriasis most often appears between
the ages of 15 and 35; however, it can develop at any time—a first-time diagnosis
of psoriasis has been seen in elderly people, small children and even newborn
babies. Psoriasis in infants is rare, but between 10 percent and 15 percent of
people with psoriasis get it before age 10. Between 150,000 and 260,000 new
cases of psoriasis are diagnosed each year.

The skin, the largest organ in the body, plays an important role. It controls body
temperature and serves as a barrier to infection. Large areas of psoriasis can
lead to infection, fluid loss and poor blood flow (circulation).

Psoriasis is a chronic (life-long) illness. Most people need ongoing treatments and
visits to the doctor. In severe cases, people may need to be hospitalized. About 56
million hours of work are lost each year by people who suffer from psoriasis, and
between $1.6 billion and $3.2 billion is spent per year to treat psoriasis.

There are five different types of psoriasis. The most common form of psoriasis is
called "plaque psoriasis," which is characterized by well-defined patches of red,
raised skin. About 80 percent of people with psoriasis have this type. Plaque
psoriasis can appear on any skin surface, although the knees, elbows, scalp,
trunk and nails are the most common locations.

The other types of psoriasis are:

Guttate: small, red, individual drops on the skin

Inverse: smooth, dry areas of skin, often in folds or creases, that are red and
inflamed but do not have scaling

Erythrodermic: periodic, widespread, fiery redness of the skin

Pustular: involves either generalized, widespread localized areas of reddened skin
and/or pustules, particularly the hands and feet (palmo-plantar pustular psoriasis)

Typically, people have only one form of psoriasis at a time. Sometimes two
different types can occur together, one type may change to another type, or one
type may become more severe. For example, a trigger may convert plaque
psoriasis to pustular.

Although the reasons for the changes are not well understood, some triggers may
include abrupt withdrawal of medications; an allergic, drug-induced rash that
brings on the Koebner response (psoriasis appearing on the site of skin injuries);
and severe sunburning.

The different types of psoriasis not only have different appearances, but also may
require different types of treatment. It is very important that you talk with your
physician about what course of action to take with your type of psoriasis.

Psoriatic Arthritis

Psoriatic arthritis is a specific type of arthritis that has been diagnosed in
approximately 23 percent of people who have psoriasis, according to the Psoriasis
Foundation’s 2001 Benchmark Survey.

It commonly affects the ends of the fingers and toes. It can also affect the spine
and other joints in the body. The disease can be difficult to diagnose, particularly
in its milder forms and earlier stages. Early diagnosis, however, is important for
preventing long-term damage to joints and tissue.

There are five types of psoriatic arthritis: symmetric, asymmetric, distal
interphalangeal predominant (DIP), spondylitis and arthritis mutilans.

Symmetric Arthritis
Occurs in about half of those with psoriatic arthritis
Similar to rheumatoid arthritis, but generally milder with less deformity
Usually affects joints on both sides of body
Can be disabling in about half of all cases
Psoriasis that occurs at the same time is often severe

Asymmetric Arthritis
Effects about 35 percent of people with psoriatic arthritis
Generally mild, although some people will develop disabling disease
Not occurring in the same joints on both sides of the body
Usually involves only one to three joints, such as the knee, hip, ankle or wrist
Could involve just one finger or a number of them
Hands and feet have enlarged "sausage" digits, caused by swelling and
inflammation of tendons
Joints may be warm, tender and red
Periodic joint pain usually responds to medical therapy

Distal Interphalangeal Predominant (DIP)
Occurs in about 5 percent of people with psoriatic arthritis
Primarily involves the joints closest to the nail of the fingers and toes
Sometimes confused with osteoarthritis, but nail changes are usually prominent

Spondylitis
Inflammation with stiffness of the neck, lower back, pelvic area or spinal vertebrae
are common symptoms
Motion is painful and difficult
In about 5 percent of individuals, inflammation of the spinal column is the
predominant symptom
May also occur in the hands, arms, hips, legs and feet
When severe, may be associated with generalized symptoms
May lead to iritis—an inflammation of the eye that results in redness and sensitivity

Arthritis Mutilans
Affects fewer than 5 percent of people with psoriatic arthritis
Severe, deforming and destructive arthritis
Principally affects the small joints of the hands and feet
May also cause neck or lower back pain
Can progress over months and years