Medicine – Juvenile Chronic Arthritis

Juvenile chronic arthritis, now more commonly referred to as juvenile idiopathic arthritis (JIA), is a group of chronic inflammatory joint disorders that begin during childhood. The diagnosis is based on persistent arthritis, onset before adulthood, and exclusion of other identifiable causes of joint inflammation. The condition may affect a single joint or several joints and can vary considerably in severity and systemic involvement.

1. Persistent Arthritis

A key diagnostic feature is the presence of arthritis affecting at least one joint for more than three months. Arthritis is characterised by joint swelling or by a combination of pain, stiffness, warmth, and limitation of movement. The persistent nature of the inflammation helps distinguish juvenile chronic arthritis from short-lived joint symptoms caused by transient infections or minor injuries.

2. Onset Before 16 Years of Age

The disease begins before the age of 16 years. Symptoms may develop gradually or more abruptly, depending on the subtype. Children may present with joint pain, morning stiffness, swelling, reduced movement, or difficulty using the affected limb. In younger children, the first sign may simply be limping or reluctance to participate in normal activities.

3. Exclusion of Other Causes

Juvenile chronic arthritis is a diagnosis of exclusion, meaning that other disorders capable of producing arthritis must first be considered and ruled out. These include infections, connective tissue diseases, malignancy, trauma, and other inflammatory or metabolic conditions. Clinical assessment, laboratory investigations, and imaging are used as needed to exclude alternative explanations for the joint disease.

Still’s Disease

Still’s disease represents the systemic form of juvenile chronic arthritis and accounts for approximately 10% of cases in older classifications. Unlike other forms that mainly affect the joints, systemic juvenile arthritis may involve the entire body and can produce prominent constitutional and inflammatory symptoms.

1. Fever

A characteristic feature is high spiking fever, often occurring once or twice daily and returning toward normal between episodes. The fever may precede the development of obvious arthritis and is usually accompanied by other systemic inflammatory features.

2. Evanescent Salmon-Pink Rash

Patients may develop an evanescent, macular, erythematous rash that is classically described as salmon pink. The rash tends to appear during febrile episodes and may fade when the temperature falls. It commonly affects the trunk and proximal limbs and is usually non-pruritic.

3. Arthritis

Arthritis is an essential feature, but the systemic manifestations may appear before the joint inflammation becomes obvious. Over time, multiple joints may become involved, and persistent inflammatory arthritis can lead to pain, stiffness, restricted movement, and functional impairment. In Still’s disease, therefore, fever and rash may precede the onset of arthritis, which can initially make the diagnosis less straightforward.