Updated May 08, 2015.

What Is Psoriatic Arthritis?:

Psoriatic arthritis is a type of arthritis associated with psoriasis (a skin condition characterized by red, patchy, raised or scaly areas) and chronic joint symptoms. The symptoms of psoriasis and joint inflammation often develop separately.

• Psoriatic Arthritis Screening Quiz

In 85 percent of patients, symptoms of psoriasis precede arthritis symptoms. Arthritis develops before psoriasis in up to 15 percent of patients.

What Symptoms Are Associated With Psoriatic Arthritis?:

Symptoms associated with psoriatic arthritis vary in how they occur (i.e. symmetrical or asymmetrical) and what joints are affected. Any joint in the body can be affected. When psoriasis causes pitting and thickened or discolored fingernails, the joints nearest the fingertips are likely to become arthritic. Common symptoms associated with psoriatic arthritis include fatigue, swollen fingers and toes, morning stiffness of joints, tendinitis, low back pain, conjunctivitis.

What Are the Types of Psoriatic Arthritis?:

Psoriatic arthritis belongs to a group of arthritic conditions known as spondyloarthropathies. There are five recognized types of psoriatic arthritis differentiated by symptoms. The five types, which can overlap, are:

• symmetric
• asymmetric
• distal interphalangeal predominant
• spondylitis
• arthritis mutilans

What Is Symmetric Psoriatic Arthritis?:

Symmetric psoriatic arthritis affects joints on both sides of the body (i.e. both knees, both hips), usually affecting multiple joints.

It is similar to rheumatoid arthritis but is usually milder with less deformity. About 25 percent of psoriatic arthritis patients have this type of the disease.

What Is Asymmetric Psoriatic Arthritis?:

Asymmetric psoriatic arthritis does not affect the same joints on both sides of the body. Any joint can be affected though. Sausage-like appearance of fingers and toes is common. Joints may be red, warm, swollen and painful. Generally considered a mild form of psoriatic arthritis, it may become disabling in some patients. About 80 percent of psoriatic arthritis patients are affected by this type of the disease.

What Is Distal Interphalangeal Predominant (DIP) Psoriatic Arthritis?:

Distal Interphalangeal Predominant (DIP) psoriatic arthritis is considered the "classic type", according to the National Psoriasis Foundation, although it occurs in only about 5 to 10 percent of psoriatic arthritis patients. The primary features of this type of psoriatic arthritis are the involvement of the distal joints of the fingers and toes (the joint closest to the nail) as well as evidence of nail changes.

What Is the Spondylitis Type of Psoriatic Arthritis?:

Spondylitis is a type of psoriatic arthritis with inflammation of the spine as the primary symptom. About 5 to 20 percent of psoriatic arthritis patients are affected with the spondylitis type. About half of the patients with spondylitis are positive for HLA-B27, a genetic marker.

What Is the Arthritis Mutilans Type of Psoriatic Arthritis?:

Arthritis mutilans is a type of psoriatic arthritis which is considered severe, disabling, and rare. Less than 5 percent of people with psoriatic arthritis are affected. Joint deformity characterizes arthritis mutilans with the small joints of the hands and feet most affected. Neck pain and low back pain are also associated with this type of psoriatic arthritis.

Diagnosis and Treatment of Psoriatic Arthritis:

There is no single test used to diagnose psoriatic arthritis. Physical examination, blood tests, x-rays, and MRI are used to rule out other types of arthritis with similar symptoms:

• rheumatoid arthritis
• gout
• reactive arthritis

Early diagnosis is important so proper treatment can begin. Medications used to treat psoriatic arthritis include NSAIDs, DMARDs, and biologics. Topical treatments and phototherapy may be used to treat psoriasis. Complementary treatments also offer relief.

Prevalence of Psoriatic Arthritis:

According to the National Institutes of Health, between 5.8 and 7.5 million Americans have psoriasis. According to the Arthritis Foundation, psoriatic arthritis affects 5 to 8 percent of people who have psoriasis. The age of onset of psoriatic arthritis is usually between 30 and 50 years of age, but it can develop at any age. Men and women are equally affected.

<sub>Sources:

Psoriatic Arthritis, Arthritis Foundation

Psoriatic Arthritis, National Psoriasis Foundation

The Five Types of Psoriatic Arthritis, National Psoriasis Foundation

Psoriatic Arthritis, American College of Rheumatology

Arthritis, A Cleveland Clinic Guide, John Clough, M.D.</sub>