Psoriatic arthritis is an inflammatory arthritis associated with psoriasis. This may manifest as:

• Arthritis involving primarily the small joints of fingers or toes
• Asymmetrical arthritis, which involves joints of the extremities
• Symmetrical polyarthritis, which resembles rheumatoid arthritis
• Arthritis mutilans, which is rare but very deforming and destructive
• Arthritis of the sacroiliac joints and spine (psoriatic spondylitis)

Patterns may change with time in individual patients, and some patients may show overlapping features or more than one type. Sometimes arthritis is associated with inflammation of the eyes, or inflammation at the bony sites of attachment of ligaments and tendons. Psoriatic arthritis causes not only the joints to swell, but also the surrounding tissues (muscles, skin, tendons, ligaments). Over 80% of people with psoriatic arthritis also have involvement of the finger and toenails. If you have psoriatic arthritis your fingers or toes may become red and swell, and have a sausage-like appearance. Not all the fingers or toes may be involved. Your nails might also get small holes in them (pitting) or may detach from the skin. The exact cause is unknown, but immune, genetic, and environmental factors are suspected. Up to 40% of patients with psoriatic arthritis may have a history of psoriasis or arthritis in family members. Both psoriasis and psoriatic arthritis flare up in the presence of immunodeficiency due to HIV infection.

Psoriatic arthritis affects at least 10% of the 3 million people with psoriasis in the United States. It affects men and women equally and usually begins between 30-50 years of age, but can begin in childhood. Psoriatic arthritis may precede the onset or the diagnosis of psoriasis in up to 15% of patients. Up to 30% of people with psoriasis also get psoriatic arthritis.

Establishing the correct diagnosis is very important because something can be done to manage most forms of arthritis, and most therapies work best when started early in the disease. Your doctor will probably be able to more easily diagnose you having psoriatic arthritis if you have psoriasis along with a single or several red, swollen fingers or toes. Usually, if your nails and skin are affected along with your joints, a firm diagnosis can be made.

However, since this form of arthritis is similar to other forms such as gout, Reiter's syndrome and rheumatoid arthritis, your doctor may perform a physical examination and order various tests to assist in diagnosis. X-rays are often ordered to look for changes to the bone. Blood and joint fluid tests may be done to rule out other conditions such as rheumatoid arthritis, reactive arthritis or gout.

Once the diagnosis is confirmed, various treatments can help decrease your pain and stiffness and increase your movement. Treatment of psoriatic arthritis is for both the skin condition and the arthritis. For mild psoriatic arthritis the treatment plan usually is comprised of medication, physiotherapy and daily-living adjustments. Your active involvement in developing your prescribed treatment plan is essential.