Childhood arthritis (juvenile arthritis or pediatric rheumatic disease) is an umbrella term used to describe any rheumatic disease or chronic arthritis-related condition which affects individuals under the age of 16. Most types are autoimmune disorders.^[1]

Several types of childhood arthritis exist, including juvenile idiopathic arthritis, juvenile myositis, juvenile lupus, juvenile scleroderma, vasculitis, and fibromyalgia.^[2]

General signs of childhood arthritis disorders include:

• Joints: Swollen, stiff, red, warm, and/or painful joints^[2]
• Eyes: Painful/dry eyes, sensitivity to light and/or difficulty seeing caused by uveitis^[2]
• Skin: Scaly red rash (psoriatic), light spotted pink rash (systemic), butterfly shaped rash across the bridge of the nose and cheeks (lupus) or thick, hardened patches of skin (scleroderma)^[2]
• Organs: Digestive tract (diarrhea and bloating), lungs (shortness of breath) and heart^[2]
• Other: Fatigue, appetite loss, and/or high, spiking fever^[2]

The most common type of childhood arthritis, juvenile idiopathic arthritis (previously known as juvenile rheumatoid arthritis (JRA) or juvenile chronic arthritis (JCA))^[3] can be divided into three main forms: The classification is based upon symptoms, number of joints involved and the presence of certain antibodies in the blood.^[1][4]

1. Polyarticular arthritis is the first type of arthritis, which affects about 30–40% of children with arthritis and is more common in girls than boys.^[1][4][5][6] Typically five or more joints are affected (usually smaller joints such as the hands and feet but many also affect the hips, neck, shoulders and jaw).^[1][5]
2. Oligoarticular (aka pauciarticular) arthritis can be early or late onset and is the second type of arthritis, affecting about 50% of children with juvenile arthritis.^[1][4][5] This type affects fewer than four joints (usually the large joints such as knees, ankles or wrists) and may cause eye inflammation in girls with positive anti-nuclear antibodies (ANA).^[1][4] Girls younger than eight are more likely to develop this type of arthritis.^[7][4]
3. Systemic disease is the least common form, with 10–20% of children (boys and girls equally) being affected with limited movement, swelling and pain in at least one joint.^[1][5] A common symptom of this type is a high, spiking fever of 103 °F (39.4 °C) or higher, lasting for weeks or months, and a rash of pale red spots on the chest, thighs or other parts of the body may be visible.^[1]

In most cases, juvenile arthritis is caused by the body attacking its own healthy cells and tissues, i.e. autoimmunity, causing the joint to become inflamed and stiff.^[8][4] Once the joint has become inflamed and stiff, damage is done to the joint and the growth of the joint may by changed or impaired.^[4] The underlying cause in the malfunction of the autoimmune system is unknown; dietary habits and emotional state seem to have no effect on the disease.^[9][10]

Early diagnosis and treatment by a pediatric rheumatologist or a rheumatologist can help manage inflammation, relieve pain, and prevent joint damage.^[1][4] However, it is difficult for doctors to diagnose the disease.^[11][9] Careful examination, laboratory tests (blood and urine), and various forms of imaging like X-rays may be some of the tests conducted by a doctor.^[1][4] Doctors may perform some of the following tests to diagnose the condition^[11]

• ANA (Antinuclear Antibody) Test^[12]
• Joint Aspiration^[13]
• Rheumatoid Factor (RF) Test^[14]

The treatment of most types of juvenile arthritis include medications, physical therapy, splints and in severe cases surgery.^[4] Methotrexate is commonly prescribed to children with juvenile arthritis.^[15] These treatments are focused on reducing swelling, relieving pain and maintaining full movement of joints.^[1] Children are encouraged to be involved in extra-curricular activities, physical activity when possible, and to live a "normal" life.^[1][6]

In the US it affects about 250,000-294,000 children making it one of the most common groups of childhood diseases.^[4]