Undifferentiated JIA

When a young person has joint pain, doctors will take a careful history to determine the cause.  Has the child been sick?  Was there a known injury?  When did the pain begin? Is there also swelling/redness/heat? Is it a single joint, or multiple joints? How long has the problem been going on?  Has the child been camping or playing in a wooded area where there are ticks?  Is there anything that makes the pain better?  Is there anything that makes the pain worse?  Has this ever happened before?  Has anything similar happened to any relatives?…

Doctors will make a list (called the differential diagnosis) of all the things that could possibly cause the symptoms, look for patterns to see what is the most likely cause, eliminate the most dangerous (cancer, etc.), and try to find a diagnosis.  The diagnosis then dictates appropriate treatment.

Sometimes, unfortunately, the problem isn’t clear and multiple doctor visits and tests are needed. When the doctors says, “Try this, and follow up with me,” definitely follow up with the same physician.  If you get frustrated and switch doctors, the new doctor has to start all over at the beginning, and it will delay diagnosis. When you return to the original doctor, that person is already familiar with the problem and can immediately proceed to the next step.

If the family physician or pediatrician determines that the joint pains indicates the child should be referred to a rheumatologist, it means that the doctor suspects some type of juvenile arthritis (and if you’re asking yourself, “Why does my child need to see a rheumatologist?” now you know).

Pediatric rheumatologists will consider all of the child’s symptoms and history in trying to determine the reason for the pain.  Does the child have arthritis, and if so, which type?  The doctor will consider diseases that can cause joint pain, including myositis, Kawasaki disease, scleroderma, lupus, and reactive arthritis.  If those are ruled out, yet the child has joint pain, it might be arthritis that has no known cause.  This it is called idiopathic arthritis.  The next step is to determine which type of Juvenile Idiopathic Arthritis (JIA) the child has.

Again, the doctor will be looking for patterns by considering these (and other) criteria:

  • number of joints affected (1-4, vs. 5+)
  • which joints are affected (spine/neck vs fingers/toes vs knees/hips)
  • percentage of finger/toe swelling
  • rough, dry skin on elbows/knees
  • appearance of fingernails and toenails (do not sand/buff/polish)
  • body temperature (fever vs low temp vs normal)
  • rash (color, location, flat/raised)
  • presence of tendonitis/bursitis
  • family history
  • results of lab tests
  • intestinal distress
  • response to anti-inflammatory medication

Many times the diagnosis will be obvious to an expert. Every type of JIA has specific criteria that must be met for a diagnosis.   Sometimes, however, the answer is not clear. Perhaps the child doesn’t meet all of the criteria for a definitive diagnosis, or perhaps the child meets criteria for more than one type of JIA.  In those frustrating instances, doctors say that the disease has not declared (differentiated) itself yet, and the diagnosis is Undifferentiated JIA.

Resources:

Questions and Answers about Juvenile Arthritis
ILAR Classification for JIA
Juvenile Idiopathic Arthritis
Early Identification of Juvenile Idiopathic Arthritis

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