Juvenile arthritis, or inflammation of the joints, affects close to 300,000 children in the United States, according to a 2007 study by the Centers for Disease Control and Prevention. The most common type, juvenile rheumatoid arthritis, or juvenile idiopathic arthritis, is a chronic, long-lasting disease that can affect the joints in any part of the body in children under 16 years of age. The cause is unknown, but it is believed that the immune system attacks the lining of tissue inside the joints. The course of the disease may be brief and mild, or it may be debilitating and long-lasting. Juvenile rheumatoid arthritis is categorized into types according to the location of symptoms and the number of joints involved.
Systemic Juvenile Rheumatoid Arthritis
Formerly called Still's disease, systemic juvenile rheumatoid arthritis is the least common form, comprising approximately 10 to 20 percent of all cases, according to the Arthritis Foundation. Systemic JRA involves many parts of the body and affects boys and girls equally. This form of JRA is characterized by swollen lymph nodes, fevers as high as 103 degrees, and rashes on the extremities and trunk. Internal organs, including the liver, spleen, lungs and heart, may become inflamed and enlarged. The eyes, however, are rarely affected.
Polyarticular Juvenile Rheumatoid Arthritis
Polyarticular JRA, the most common type, involves pain, stiffness, swelling and redness in five or more joints during the first six months of disease. It may involve large and small joints of the legs and arms, as well as the jaw and neck, but symptoms usually do not involve other parts of the body, according to MayoClinic.com. Girls are more commonly affected than boys.
Pauciarticular Juvenile Rheumatoid Arthritis
Pauciarticular JRA, also called oligoarthritis, affects four or fewer joints during the first six months of the disease, according to MayoClinic.com. The joints affected are most often the knee, ankle and wrist joints. This group of patients is most likely to experience eye inflammation, which can cause blindness in rare cases. This type is more common in girls than in boys. Many children outgrow this type of arthritis by adulthood, but in some the disease may involve more joints over time, according to the Arthritis Foundation.
Psoriatic Arthritis
Psoriatic arthritis affects children who have arthritis with the rash of psoriasis, according to the Cleveland Clinic, although the arthritis and psoriasis may appear many years apart. Children frequently have nail changes that look like pitting.
Enthesitis-Related Arthritis
This type of arthritis often affects the spine, hips and enthesis, which is the attachment point of tendons to bones. It occurs primarily in boys older than 8 years, according to the Cleveland Clinic, and there is often a family history of spondylitis or arthritis of the back in male relatives. The eyes are often affected in this type of arthritis.
