What Are the Causes of Polyarthritis?

In contrast to widespread aching and other causes of extremity pain, arthritis is characterized by inflammation, stiffness, swelling, tenderness and warmth. Monoarthritis is defined as inflammation of one joint and can indicate septic arthritis, gout or tumors. On the other end of the spectrum, polyarthritis affects five or more joints. Rheumatoid arthritis (RA), systemic lupus erythematosus (lupus), psoriatic arthritis, osteoarthritis (OA) and other diseases can all present as polyarthritis. Some of these diseases have widespread and systemic effects, requiring early diagnosis and intervention.

Rheumatoid Arthritis

• RA is an autoimmune disease usually affecting five or more joints in a symmetrical fashion. Symptoms are highly variable, but joint involvement is characterized by fluid in the joints, painful joint movement and erosion of bone, cartilage and ligaments. Enlarged joints feel spongy and warm. Systemic symptoms include low-grade fever, weight loss and fatigue. In later stages, stiffness predominates. RA is confirmed by X-rays, blood tests and particularly the blood test for rheumatoid factor, the auto antibody causing the disease.

Systemic Lupus Erythematosus

• Lupus is an autoimmune disease affecting multiple organ systems due to the buildup of proteins in the vascular system. Polyarthritis is almost always one of the first symptoms, and arthritis can occur in any joint. The arthritic pain is usually not associated with specific radiological findings, joint nodules or bony deformity, but other deformities may occur, such as ulnar deviation and Swan-neck deformities in the fingers. Polyarthritis, in combination with malar rash, photosensitivity and multiple organ system involvement, are helpful in diagnosing lupus.

Psoriatic Arthritis

• Psoriatic arthritis is a form of arthritis affecting some people with psoriasis, an autoimmune disorder characterized by raised patches or lesions of dead skin cells. Psoriasis is usually diagnosed first, followed later by psoriatic arthritis. Symptoms of psoriatic arthritis are similar to RA except that the rheumatoid factor is not present. The arthritis is usually symmetric and affects the small joints of the hands, wrists, elbows, ankles and feet. Diagnosis is based upon the presence of psoriasis and arthritic pain and a negative rheumatoid factor blood test.

Osteoarthritis

• OA, also called degenerative joint disease, causes polyarthritis and is easily differentiated from other kinds of arthritis because the joint damage is mechanical (caused by trauma or overuse), inflammation is minimal and joints are cool rather than warm. Symptoms include bony enlargement, locked joints, joint tenderness, stiffness and decreased joint mobility. OA does not have systemic effects and is diagnosed by clinical symptoms and X-rays.

Miscellaneous Causes

• Polyarthritis also has many other less common causes that have inflammatory, infectious, metabolic and other origins. For example, Still's disease, scleroderma, sarcoidosis, reactive arthritis, gout, cancer, Whipple's disease and hemochromatosis can cause polyarthritis.