What are the key clinical features to consider when diagnosing Juvenile Idiopathic Arthritis (JIA) in a child?

Key clinical features for diagnosing Juvenile Idiopathic Arthritis (JIA) in a child include:

• Persistent arthritis: Swelling, pain, or limitation of movement in one or more joints lasting for at least 6 weeks, not explained by other causes, is the hallmark feature ¹.
• Joint involvement pattern: Oligoarthritis (≤4 joints) is common, often affecting large joints such as knees and ankles, but polyarthritis (≥5 joints) can also occur ¹.
• Morning stiffness and reduced range of motion: Children often present with stiffness, especially in the morning or after periods of inactivity, which improves with movement ¹.
• Systemic features: Some subtypes of JIA may present with systemic symptoms such as fever, rash, lymphadenopathy, hepatosplenomegaly, or serositis, which should raise suspicion ¹.
• Absence of other causes: Diagnosis requires exclusion of other causes of arthritis such as infection, trauma, malignancy, or other rheumatological conditions ¹.
• Laboratory and imaging findings: While no single test confirms JIA, inflammatory markers (ESR, CRP) may be elevated; ANA positivity is common in oligoarticular JIA; imaging (ultrasound or MRI) can detect synovitis and joint damage early (Dimitriou et al., 2017).
• Age of onset: Typically presents before 16 years of age, with peak incidence between 1 and 3 years for oligoarticular subtype ¹.

Integrating UK clinical guidelines with recent literature emphasizes the importance of a thorough clinical assessment focusing on persistent joint inflammation and exclusion of other diagnoses, supported by targeted laboratory and imaging investigations to confirm synovitis and guide management (Dimitriou et al., 2017; Ruperto et al., 2021).