The JIA criteria also sub-divides children with polyarthritis into two categories, those who test positive for rheumatoid factor (RF) – an antibody found in the blood – and those who don’t. The RF-positive form of the disease usually emerges in the elementary school years or later. It’s the type most similar to adult rheumatoid arthritis. Children with RF-positive polyarthritis are typically more vulnerable to severe disease and related joint erosion than those who test negative for rheumatoid factor.

Systemic: Involving about 10 percent of JIA cases, systemic arthritis affects the entire body, beyond just the joints. Both boys and girls are equally vulnerable. Although symptoms can start any time during childhood, they generally emerge by or in elementary school years.

The first sign might be a stubborn fever, sometimes appearing weeks or months before your child complains of any joint discomfort or mobility issues. The fever can be quite high, appearing once or twice daily, before returning to normal. Your child might seem, by all indications, fine in between. Fevers also may be accompanied by a faint rash, one that ebbs and flares over the course of days. Often described as pinkish or salmon-colored, it’s not contagious.

Since this illness can affect the entire body, inflammation may occur elsewhere, enlarging the spleen or irritating the membranes that cover the lungs or heart. In many cases, the fever and other systemic symptoms fade over time. Eye inflammation isn't common with systemic arthritis, but your child’s vision will still need to be checked.

The condition can influence your child’s growth and appetite, making good nutrition a high priority. But the course of the disease, including the number of joints involved, can be highly variable and individual. Only over time will your child’s doctor have a better sense of the challenges she faces.

Enthesitis-related: This type, which wasn’t included under the JRA criteria, involves inflammation of the entheses, sites where tendons attach to the bone. Boys are more often diagnosed. The arthritis can be mild, involving four or fewer joints in roughly half of cases. In some children, arthritis can move to the spine. Frequently, they test positive for the HLA-B27 gene.

Over time, your child may develop one of the various conditions also known as juvenile spondyloarthropathies, which may but do not necessarily affect the spine. Some of those diseases include: juvenile ankylosing spondylitis, arthritis associated with inflammatory bowel disease and reactive arthritis. 

Juvenile Psoriatic Arthritis: In this form of arthritis, the skin condition called psoriasis may precede or follow the symptoms of psoriatic arthritis, sometimes by years. The rash may appear as a scaly red rash, emerging behind the ears or on the eye lids, elbows, knees or scalp. Your child may have a family history of psoriasis. Another common sign: a pitting or unusual ridging on the fingernails.

Other: Any arthritis of unknown cause, with symptoms continuing at least six weeks, that doesn’t meet criteria for any one type of JIA or involves symptoms than span two or more types.

 

Adapted from Raising a Child with Arthritis. To order your copy, click here.