Psoriatic arthritis (PA) is a combination of the skin disorder psoriasis and arthritis. It causes pain and swelling in a person’s joints and thick, scaly patches of skin on some areas of the body. The disease typically affects adults in their 30s through 50s, but children can develop a form of the disease called juvenile psoriatic arthritis.

PA can appear in five major forms, with symptoms ranging from mild to severe. Most people with PA develop psoriasis long before arthritic symptoms appear. Fingers and toes are the areas of the body most commonly affected. Many patients also experience pitted, discolored nails and inflammatory eye conditions.

In most cases, patients with PA find that symptoms related to their psoriasis and arthritis tend to come and go. In addition, patients usually do not experience flare-ups of both their psoriasis and their arthritis at the same time.

There is no cure for PA, but medication, physical therapy and lifestyle changes can often relieve pain and slow the disease’s progression. People who have a parent or sibling with PA are themselves at greater risk for the disease. The condition is also associated with stress, reactions to medications or vaccines, illness and other factors. Having psoriasis, however, is the greatest risk factor for the condition.

Psoriatic arthritis (PA) is a condition in which people with psoriasis – a condition that causes inflamed, scaly skin – is accompanied by the swollen, painful joints of arthritis. It most often affects adults in their 30s through 50s, but children can develop a form of the disease called juvenile psoriatic arthritis.

PA manifests in several forms, and symptoms can range from mild to severe. Fingers and toes are the areas of the body most commonly affected. Many patients also experience pitted, discolored nails and inflammatory eye conditions such as conjunctivitis.

This form of arthritis is usually less crippling than other forms of arthritis. However, left untreated, PA can cause disability and deformity. About 20 percent of patients with PA have a severe form of the disease that is potentially deforming and debilitating, according to the Arthritis Foundation (AF).

A number of risk factors are associated with PA. The major one is having psoriasis, a skin condition that affects about 3 percent of the population, according to the AF. Between 7 and 20 percent of this population have been diagnosed with PA.

There is no cure for PA, but medication, physical therapy and lifestyle changes often can relieve pain and slow the disease’s progression.

There are five distinct types of psoriatic arthritis (PA), each with its own characteristics:

• Asymmetric arthritis. The mildest form of PA. In most cases, it affects joints on only one side of the body or different joints on each side. Joints affected include those of the hip, knee, ankle or wrist, which may feel tender or become red. One to three joints are generally involved in asymmetric arthritis. Swelling and inflammation in the tendons can cause fingers and toes to resemble small sausages, a condition known as dactylitis.
  
  
• Symmetric arthritis. Usually affects four or more of the same joints on both sides of the body. It is similar to rheumatoid arthritis (RA) but usually milder. Symmetric arthritis can cause progressively disabling joint damage. Psoriasis associated with this condition, which affects women more often than men, tends to be severe.
  
  
• Spondyloarthropathy. Characterized by inflammation of the spine and stiffness and inflammation in the neck, lower back or sacroiliac joints. In some cases, inflammation can extend to where ligaments and tendons attach to the spine. Patients may find that movement becomes increasingly painful and difficult as the disease progresses. This condition differs from ankylosing spondylitis, which may affect the entire spine and does not occur with psoriasis.
  
  
• Arthritis mutilans. A long-term, painful, crippling form of PA that affects a small percentage of people with the disease. As it progresses, arthritis mutilans destroys the small bones (a process called osteolysis) in the hands and fingers, causing permanent deformity and disability. This condition may cause the fingers and wrist to shorten, with skin folds around them (which is termed “opera glass hand”). This form tends to affect men more often than women.
  
  
• Distal interphalangeal joint predominant (DIP). Affects the small joints closest to the nails (distal interphalangeal joints) in the fingers and toes. DIP is among the least common forms of PA, and it tends to affect men more often than women. Some physicians misdiagnose DIP as osteoarthritis (arthritis that results from destruction of cartilage on the ends of the bones).

Psoriatic arthritis (PA) may be an autoimmune disorder, which occurs when the body’s immune system mistakenly begins to attack healthy cells and tissues. This abnormal response causes swelling of the joints and excessive production of skin cells, which build up as rough and dry dead skin cells that become thick scales. Scientists are unsure of why this occurs, though genetic and environmental factors appear to be at play.

People who have a parent or sibling with PA are themselves at greater risk of developing the disease. Researchers have found gene mutations that appear to be associated with PA. In some cases, fungal, viral or bacterial infection or physical trauma may trigger PA in people who have a genetic predisposition to the disease. Factors that may contribute to PA include:

• Skin injuries
• Reactions to medications or vaccines
• Infections, especially streptococcal infections
• Stress
• Alcohol and poor nutrition
• Overexposure to the sun
• Prolonged exposure to irritating chemicals such as disinfectants and paint thinners

The greatest risk factor for PA is having psoriasis. Additional risk factors include:

• Heredity. About half of the people with PA have a close relative who has the disease.
  
  
• Age. PA most commonly affects adults between the ages of 30 and 50.
  
  
• Race. Caucasians are most likely to develop PA.
  
  
• Sex. PA tends to affect men and women equally, although certain forms of the disease are more likely to affect men (DIP and spondylitis) or women (symmetric arthritis).
  
  
• Human immunodeficiency virus (HIV) infection. PA occurs more often in patients who are HIV-positive. In addition, HIV infection may exacerbate cases of psoriasis.

Most people with psoriatic arthritis (PA) develop psoriasis long before arthritic symptoms appear. In addition, there are rare cases in which joint pain may occur – sometimes for as long as decades – before skin symptoms appear. As a result, people are usually diagnosed with either psoriasis or arthritis before they are eventually diagnosed with PA, the combination of these disorders. It can be very difficult to diagnose PA without skin symptoms.

Patients are diagnosed with PA if they display the following symptoms related to each condition:

• Patches of thick, red skin covered with silvery or gray scales. These most often appear on the elbows, knees, scalp or the lower end of the spine. These patches, known as plaques, often itch or burn. Skin at the joints may crack.
  
  
• Pain, redness, swelling and reduced motion in the joints. About 95 percent of patients with PA experience swelling in joints outside the spine, according to the Arthritis Foundation (AF). Joints most often affected include the small joints at the ends of fingers and toes, giving them a “sausage” appearance. Joints in the spine and sacroiliac joints (two large joints connecting the pelvis and the triangular bone at the end of the spine) may also be affected.
  
  
• Morning stiffness (often lasting more than 30 minutes) and fatigue. Physical activity usually helps alleviate stiffness.  
  
  
• Pitted, discolored nails. About 80 percent of patients with PA have nail lesions, according to the AF. Nails in these patients often separate from the nail beds.
  
  
• Pain in the lower back or buttocks.
  
  
• Inflammatory eye conditions and eye pain. These include conjunctivitis or iritis. About 10 percent to 20 percent of children diagnosed with juvenile PA will experience inflammation of the eye, according to the AF.

Symptoms of PA often go through cycles where they improve or worsen. It is not unusual to experience outbreaks of psoriasis when joint pain goes into remission, and vice versa.

Juvenile PA is a condition that affects children (most often girls), who usually develop symptoms of the disease around age 9 or 10. Symptoms are usually mild, although they can be severe and debilitating and last into adulthood. Although children typically display symptoms similar to those of adults, they are more likely to develop skin and joint problems simultaneously. In other cases, arthritis may appear in the child before psoriasis. Because their bones are still growing, children with PA are at risk for abnormal bone development that can affect growth.

Psoriatic arthritis (PA) can be difficult to diagnose because in adults, psoriasis and arthritis rarely occur at the same time. In addition, PA also mimics other conditions, such as:

• Rheumatoid arthritis (RA). Occurs when an autoimmune response causes inflammation in the lining of the joints, especially those in the hands and feet.
  
  
• Gout. Arthritis characterized by sudden, severe attacks of pain, redness and tenderness in a single joint, usually at the base of the big toe.
  
  
• Reiter's syndrome. Form of reactive arthritis that inflames the joints, eyes, genitals, and urinary or digestive tract.
  
  
• Infection. An infection of the joint can mimic arthritis as it causes a red, swollen and inflamed joint. Psoriasis patients can have an episode of infectious joint without any evidence of arthritis related to the psoriasis. 

In attempting to diagnose PA, a physician will review the patient’s medical history and perform a physical examination. Additional tests that may be used to diagnose PA include:

• X-rays. Can reveal changes in the joints that occur in PA.  In severe disease, the distal interphalangeal (DIP) joints of the fingers or toes give a distinctive “pencil-in–cup” appearance on an x-ray.
  
  
• Arthrocentesis. A small sample of fluid is removed from a joint, typically in the knee, for laboratory analysis. A physician can use this test to rule out gout, which is indicated by the presence of uric acid crystals.
  
  
• Erythrocyte sedimentation rate (ESR). Blood test that checks ESR, or “sed rate,” by measuring how far from the top of a glass tube red blood cells (erythrocytes) fall in a given time. Generally, blood cells fall when inflammation is present. However, this test alone cannot confirm the presence of PA as inflammation can be caused by many factors.
  
  
• Rheumatoid factor (RF) test. RF is an antibody (protein made by the immune system) present in the blood of people with RA, lupus or certain other diseases. This test can help determine if a patient’s symptoms are due to PA or another condition.
  
  
• Skin biopsy. This may be needed to rule out other conditions, such as fungal infection.

Treatment of psoriatic arthritis (PA) can involve pain control, medication, patient education, physical therapy and occupational therapy. A physician is likely to prescribe a combination of medications. Some of these medications are designed to treat arthritis, others to treat psoriasis.

Medications used to treat PA include:

• Nonsteroidal anti-inflammatory drugs (NSAIDs). These include aspirin, ibuprofen and naproxen, which can help control pain, swelling and morning stiffness. NSAIDs are available in over-the-counter and in prescription formulations such as COX-2 inhibitors. In some patients, NSAIDs may cause stomach upset. They generally do not help psoriasis, and some may even make skin problems worse.
  
  
• Disease-modifying antirheumatic drugs (DMARDs). Reduce pain and inflammation while also helping to limit the amount of joint damage that occurs in PA. These drugs act slowly, and their effects may not be noticed for weeks or even months.

Methotrexate reduces skin and joint symptoms and slows the progression of arthritis in some patients. Oral methotrexate may also help symptoms of psoriasis by decreasing the production of skin cells, suppressing inflammation and inhibiting the release of histamine (substance involved in allergic reactions). Sulfasalazine, originally developed to treat inflammatory bowel disease, is also used to treat rheumatoid arthritis and PA. Potential side effects include nausea, vomiting and loss of appetite.

Gold salts, a class of DMARDs, are sometimes used to treat PA but less frequently than in the past. This is because they may make psoriasis worse in some people and can damage the kidneys and bone marrow.

• Corticosteroids. Medications that reduce inflammation and slow joint damage.  Injection of corticosteroids directly into the joint can be useful for treatment of a few joints. However, corticosteroids usually are not recommended for long-term treatment of PA, because long-term use can make them less effective and cause serious side effects, including easy bruising, thinning bones (osteoporosis), cataracts, glaucoma, diabetes, high blood pressure and a decrease in resistance to infection. In addition, some patients who stop therapy aggravate skin symptoms and even trigger pustular psoriasis, a severe form of the disease.
  
  
• Other immunosuppressants. Suppress the immune system, which mistakenly attacks healthy tissue in people with PA. Immunosuppressants include biological response modifiers (BRMs) such as tumor necrosis factor (TNF) inhibitors. TNF inhibitors block an immune system protein called tumor necrosis factor. This protein acts as an inflammatory agent in some types of arthritis. TNF blockers may slow structural damage to joints caused by PA. Side effects of immunosuppressives include increased risk of serious infections such as tuberculosis.
  
  
• Retinoids. Synthetic derivatives of vitamin A that may be prescribed for psoriasis or PA.
  
  
• Antimalarial drugs. Sometimes used to treat arthritis, but may cause flare-ups of psoriasis in people with PA.

Arthritis also may be treated with physical therapy, exercise therapy and occupational therapy, as well as treatments such as thermotherapy, massage therapy and transcutaneous electrical nerve stimulation (TENS), a form of electrical therapy.

Medications that may be used to treat mild forms of psoriasis include the following creams and ointments:

• Coal tar. Likely the oldest treatment for psoriasis, it is a thick, black byproduct of the manufacture of gas and coke. Exactly how it works is not known, but it is effective for all forms of the disease except the severe generalized pustular types.
  
  
• Anthralin. Normalizes DNA activity in skin cells and reduces inflammation. However, it can also irritate healthy skin and stain skin, clothing and bedding.
  
  
• Vitamin D analogues. Synthetic forms of vitamin D that reduce skin inflammation and help prevent skin cells from proliferating.
  
  
• Regular moisturizing creams. These can prevent skin dryness that accompanies many forms of psoriasis therapy.

Oral medications may be used to slow cell growth and suppress the immune system. In addition, psoriasis may be treated with phototherapy. This uses natural or artificial light to suppress the growth of skin cells. It is usually reserved for severe psoriasis, as it may increase the long–term risk of skin cancer.

In rare cases, joint replacement surgery (arthroplasty), typically involving the hip, knee or hand, may be performed if PA has significantly impaired joint functioning. However, few studies have been performed on the long-term outcomes. The chance that surgery becomes necessary appears to depend on how long a patient has the disease.

In most cases, there is no way to prevent psoriatic arthritis (PA). However, people can take several steps that may lessen the likelihood of experiencing progression or flare-ups associated with arthritis and psoriasis. Such steps include:

• Eat a healthy diet. To date, no specific food or nutrient has been proven to prevent or control arthritis. However, it is known that antioxidants, such as vitamins C, E and A, prevent cell damage that may contribute to arthritis. Diets high in olive oil and vegetables have been linked to reduced risk of rheumatoid arthritis, and the mineral selenium has been linked to reduced risk of osteoarthritis. Scientists have not conclusively linked any foods to arthritis flare-ups. Nonetheless, patients should exclude foods from their diets that appear to make symptoms worse.
  
  
• Maintain a healthy weight. A healthy weight places less strain on joints, leading to reduced pain and increased energy and mobility.
  
  
• Exercise regularly. In some patients, exercise alone can help relieve many of the symptoms of arthritic conditions such as pain and fatigue.
  
  
• Use cold and hot packs. Cold has a numbing effect and can dull the sensation of pain, whereas heat can relax tense muscles and relieve pain.
  
  
• Experiment with relaxation techniques. Stress can worsen symptoms associated with PA. Patients should try to reduce stress and increase relaxation through various techniques, such as meditation or prayer, yoga, tai chi, deep breathing, biofeedback, self-hypnosis, visualization or guided imagery.
  
  
• Use proper body mechanics. Individuals should observe good posture and ergonomics and avoid straining areas vulnerable to arthritis, such as finger joints.
  
  
• Care for skin. Daily bathing can help remove psoriasis scales. Use of hot water and harsh soaps should be avoided, and patients should pat themselves dry after a shower or bath and apply a moisturizing cream (without alcohol) while skin is still damp. Humidifiers can help keep inside air moist.
  
  
• Expose skin to moderate sunlight. Sunlight slows down cell growth, helping improve psoriasis. However, patients should remember that too much sunlight can damage the skin and cause skin cancer.

Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions about psoriatic arthritis (PA):

1. What tests are needed to determine whether I have PA?
   
   
2. What do these tests involve?
   
   
3. How does PA differ from other forms of arthritis I might experience?
   
   
4. What causes this disease?
   
   
5. Is PA likely to run in my family?
   
   
6. My psoriasis and arthritis rarely flare up at the same time. Is this normal?
   
   
7. What are my treatment options?
   
   
8. Which treatments do you recommend for me?
   
   
9. What side effects can I expect from medications used to treat my PA?
   
   
10. Is there a cure for my PA?
    
    
11. Can PA affect my children?