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Psoriasis What is it?

PSORIATIC ARTHRITIS: WHAT IS IT?
Psoriasis Association of Victoria Inc.
(Reprinted from the American National Psoriasis Newsletter)

Psoriatic Arthritis is different from Rheumatoid arthritis.
The association between psoriasis and arthritis has been recognised for many years. Approximately 5-10% of persons with psoriasis have psoriatic arthritis. This form of arthritis is similar to, but distant from, rheumatoid arthritis. Psoriatic arthritis was identified as a separate from of arthritis in part through the discovery of the rheumatoid factor. This factor is an anti-gamma globulin antibody found in the blood of 70% of rheumatoid arthritis patients, but absent from the blood of most patients who have psoriasis arthritis. The conclusion that psoriatic arthritis is distant from rheumatoid arthritis is further supported by other clinical signs identified in recent years.

Symptoms
The initial symptoms of psoriatic arthritis are like those of other types of arthritis. There can generally be discomfort, pain, throbbing, swelling of single or multiple joints and tenderness in any joint. Some joints are particularly apt to be involved, including the last joint in the fingers or toes, sacrum (lower back), wrists, knees, or ankles. Inflammation in the joints may stimulate nerve endings causing pain. Exactly how this happens and how it relates to psoriasis on the skin is unknown.

Other symptoms include morning stiffness and fatigue. Some persons will also develop inflammatory eye diseases, including conjunctivitis. Nail changes may also occur.

Psoriatic arthritis differs
Psoriatic arthritis differs from rheumatoid arthritis in several ways. First, psoriatic arthritis more frequently involves the last joint of the fingers and toes, whereas rheumatoid arthritis more commonly affects the hand, finger and toe joints closest to the palm. Psoriatic arthritis can affect joints on the fingers and toes in characteristic ways that can be revealed through x-ray at a certain stage.

Secondly, psoriatic arthritis is more likely to appear asymmetrically (affect one joint). Rheumatoid arthritis is more likely to appear symmetrically (affecting a pair of joints). The simultaneous presence of psoriasis and nail malformation are also markers of psoriatic arthritis. Nail malformation is rare in rheumatoid arthritis. Nodules under the skin do not appear in psoriatic arthritis as they do in rheumatoid arthritis. The rheumatoid factor is usually absent in the blood of psoriatic patients.

Other associations
Psoriatic arthritis can be confused with Reiter's syndrome and gout. Reiter's syndrome is a non-venereal inflammation of the urethra followed by conjunctivitis (eye inflammation) and arthritis. The syndrome produces skin lesions of the palms, soles, penis and in the mouth. The lesions in Reiter's syndrome may resemble pustular psoriasis. Psoriasis sometimes appears with the lesions in this syndrome early in the course of the disease.

Acute psoriatic arthritis can also stimulate a type of gout. Gout is a form of arthritis or inflammation about a joint. The inflammation is caused by excess uric acid in the blood. Attacks occur suddenly and are accompanied by great pain. The big toe is a frequent site. Hyperuricemia (excess uric acid in the blood) occurs in 10-20% of patients with psoriatic arthritis, but classical gout is uncommon. Acute gouty arthritis is usually self-limiting and lasts, untreated, a couple of weeks.

There has also been reports of a possible association between HLA antigens, found on the surface of white blood cells, and psoriatic arthritis. These antigens may predispose a person to developing psoriatic arthritis. Data from family surveys suggest a possible genetic predisposition to psoriasis and psoriatic arthritis. What role these markers play is still subject to speculation and further study.

There are three general types of psoriatic arthritis.

Asymmetric arthritis
The most common form of asymmetric arthritis, which normally involves the joint of the fingers and toes. It can affect any joint, such as the knee, hip, ankle and wrist. One finger may be involved or many can affected.

Commonly observed among the latter are the "sausage" digits of the hands and feet. The term describes the appearance of the enlarged affected digit. The joints are usually warm, tender and red. It has been estimated that 55-70% of patients with psoriatic arthritis may have this form of arthritis.

Asymmetric arthritis is associated with psoriatic nail changes of the finger. This form is generally mild and the patient faces a mild to moderately progressive disease course. Persons may experience intermittent joint pain which is usually responsive to medical therapy.

Symmetric arthritis
The second most common form is symmetric arthritis. This form occurs in 15-70% of patients. Symmetric arthritis affects any pair of joints, including the last joint of the fingers and toes. This form can be severe and disabling. The associated psoriasis is often severe. Nail malformation can also be present.

Psoriatic spondyloarthritis
This third type is the least common affecting 5-33% of persons with psoriatic arthritis. Inflammation and stiffness of the lower back or spinal vertebrae are the most common manifestations of spondyloarthritis. There can also be peripheral joint disease. This form may appear in the joints of the hands and arms, hips, legs and feet. It can also attack the connective tissue. The joints can stiffen, swell and become tender, eventually making motion difficult and painful.

Additional aspects
Arthritis mutilans is a severe, deforming and destructive arthritis principally affecting the small joints of the hands and feet, occurring in approximately equal frequency in the three groups. It occurs in about 5% of the psoriatic arthritic cases. The disease has a variable progressive course that can extend over months or years. There is a tendency for the arthritic exacerbations and remissions to coincide with the skin flares and remissions and for there to be simultaneous occurrences of lower back pain.

In Childhood
The number of children affected by psoriatic arthritis is thought to be very small. In study of 549 persons, 30% developed psoriasis prior to age 15, but no associated arthritis was reported. In another study of 316 children with juvenile rheumatoid arthritis, 3.2% were diagnosed as having psoriatic arthritis. In one study of psoriatic arthritic patients, two children were reported to have developed psoriatic arthritis prior to age 15. The psoriasis began at ages 12 and 14. Both children experienced mild psoriatic arthritis in the fingers and toes and had nail malformation. Neither child experienced weight loss or growth failure.

The course of psoriatic arthritis
The causes of psoriatic arthritis are not known. The onset may be at any age, but the peak occurrence seems to correspond with that of rheumatoid arthritis, which is between ages 30 and 50. Women seem to be affected more than men.

As there is no cure, therapy is aimed at controlling the symptoms of the disease. Various treatments are applied to relieve the pain, reduce inflammation, prevent damage to joints, prevent deformities and to keep joints mobile and functioning properly. It is not believed that therapy can stop the basic disease process.

The course of psoriatic arthritis is unpredictable. In a recent study, the majority of patients experienced remissions that lasted from several months to 15 years. These remissions were characterised by the absence of joint pain, improved function, and freedom from general symptoms of the disease. Remissions rarely occurred spontaneously. They were usually a result of therapy. The investigators concluded that the prognosis of psoriatic arthritis requires an evaluation of many factors, including sex, age of onset of the arthritis, distribution of the arthritis, and the individual's genetic predisposition.

The treatments
Treatment is normally conducted at home. However, in some cases, hospitalisation may be required to control an acute flare-up, or in extreme cases, to perform reconstructive surgery. Improvement from a treatment program is gradual but can be achieved through adherence to the program. Because the disease can vary in each individual and because the patients themselves vary in the way they react to treatment, the physician may have to try a number of drugs to find the most effective for the individual.

There are several different treatments for psoriatic arthritis. Mild psoriatic arthritis is treated like other forms of arthritis with aspirin, anti-arthritis, anti-arthritis drugs such as indomethacin, and related non-steroidal, anti-inflammatory drugs. When only a few joints are involved, an excellent response can be obtained by the local injection of steroids by a rheumatologist into the affected joints without requiring oral medications. Symptomatic care involving heat, warm water soaks, exercise programs can also be used with appropriate medical consultation.

Extensive or severe psoriatic arthritis can be treated successfully with methotrexate. Methotrexate can be effective for those patients with severe psoriatic arthritis who do not respond to the standard anti-arthritis medications or those patients who do not tolerate standard anti-arthritis medications and can only tolerate methotrexate.

Injections of gold salts may also be used on occasion for those patients with severe and destructive psoriatic arthritis. Traditionally, gold therapy has been believed to be of limited usefulness in treating psoriatic arthritis, but some investigators have reported success with this therapy.

Anti-malarial drugs are not generally recommended for the treatment of psoriatic arthritis because of the risk of exfoliative dermatitis (chronic inflammation of the skin commonly involving the whole surface with scaling or flaking). However, one study has reported that 72% of the psoriatic arthritis patients who used an anti-malarial drug in combination with aspirin experienced improvement in their arthritis with no skin eruptions.

Choosing a treatment
There is no correlation between location of psoriatic skin lesions and the location of joints involved in the arthritis. In other words, the arthritis does not necessarily appear in the part of the body where the lesions are located. One exception to this might be when there is no substantial involvement of the fingers or toes.

It is thought by some investigators that improvement of the psoriasis-involved skin is associated with improvement of the arthritis. There is no scientific evidence that there is a correlation, but investigators report that with some individuals, joint disease remits when the psoriasis clears. They, therefore, recommend that the skin be treated along with the arthritis.

The psoriatic skin lesions in patients who develop arthritis are identical to those seen in patients who do not manifest joint disease. Skin disease usually precedes the development of joint symptoms. Nail changes are found more frequently in patients with psoriatic arthritis than in patients without.

Dr Gerrald Weinstein of University of California, Irvine, suggests that patients with symptoms of psoriatic arthritis should first see the dermatologist who is treating the psoriasis. Appropriate initial therapy might be started by the dermatologist. If significant arthritis develops, a rheumatologist should be consulted.

If you are interested in learning more about our Association or have specific queries about Psoriasis, please call (03) 9530 4454 or write to the address below.

MEMBERSHIP of the Psoriasis Association of Victoria Inc., entitles the member to :
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Psoriasis Association of Victoria
PO Box 1151
Glen Waverley, Vic 3150