Your Guide to Juvenile Idiopathic Arthritis and Its Many Types

Rheumatoid arthritis (RA) in children is now known as juvenile idiopathic arthritis (JIA). There are several types of JIA, all of which cause pain and stiffness in the joints. JIA can last for months, years, or a lifetime.

Rheumatoid arthritis (RA) in children used to be called juvenile rheumatoid arthritis (JRA) but is now called juvenile idiopathic arthritis (JIA). The name changed because doctors wanted to make it clear that rheumatoid arthritis in children is a unique condition, different from rheumatoid arthritis in adults.

One of the most significant differences between RA and JIA is that children can outgrow their condition, while adults will always have it.

There are several subtypes of JIA, all of which cause pain, stiffness, and inflammation in the joints.

This article will explore the most common types of JIA in children, their symptoms, the diagnosis process, treatment, and complications.

JIA is the most common type of arthritis affecting children and teens. But the condition has several different subtypes . These include:

Oligoarticular juvenile idiopathic arthritis

This is the most common type of JIA. It initially affects 1 to 4 joints.

Doctors classify this type of JIA as persistent if symptoms continue for 6 months or longer. If symptoms worsen and 5 or more joints are affected after 6 months, doctors call it extended.

This type typically affects large joints like the ankles and knees. It may also involve eye inflammation called uveitis.

Polyarticular juvenile idiopathic arthritis-rheumatoid factor negative

Polyarticular juvenile idiopathic arthritis is the second most common type of JIA. It affects 5 or more joints during the first 6 months. Blood tests for rheumatoid factor, a marker of autoimmune disease, have negative results. Some children with this type develop chronic uveitis.

Polyarticular juvenile idiopathic arthritis-rheumatoid factor positive

In this type, 5 or more joints become affected within 6 months. But the child will have positive rheumatoid factor test results, which indicates an autoimmune disease. This type is very similar to adult RA and commonly affects preteen and teen girls.

Enthesitis-related juvenile idiopathic arthritis

Enthesitis is inflammation at the connection of a ligament or tendon to a bone. It commonly occurs in the knees, heels, and soles of the feet. This type combines flares of enthesitis and arthritis. Some children also develop acute anterior uveitis or inflammation in the front of the eye.

Psoriatic juvenile idiopathic arthritis

Children with this type typically develop psoriasis first, which is a condition affecting the skin. Sometimes signs of arthritis, like joint stiffness and pain, can develop before a psoriasis diagnosis is made. Other signs of this condition include pitted fingernails and swollen fingers and toes.

Systemic juvenile idiopathic arthritis

This type can affect the entire body and often begins with a fever and rash that comes and goes over the course of at least 2 weeks. The joints may become swollen and painful, but this may occur after the fever has cleared. In severe cases, inflammation forms in and near organs and the lining of organs like the heart and lungs.

Undifferentiated arthritis

This type includes those with symptoms that do not fit in with other types or that fit with more than one type.