Diagnostic Criteria for Juvenile Idiopathic Arthritis (JIA)

Classification Criteria

The International League of Associations for Rheumatology (ILAR) criteria require arthritis persisting for at least 6 weeks in a patient under 16 years of age, with exclusion of other potential causes 1, 2
Arthritis (joint swelling or limitation of motion with pain, heat, or tenderness) persisting for at least 6 weeks is a key criterion for JIA diagnosis, as per the ILAR criteria 2, 3
Age of onset less than 16 years is a necessary condition for JIA diagnosis, according to the ILAR criteria 4, 3
Exclusion of other causes of arthritis through comprehensive evaluation is essential for JIA diagnosis, as recommended by the ILAR criteria 1

Systemic JIA is characterized by arthritis with or preceded by daily fever for at least 2 weeks, plus one or more of: evanescent rash, lymphadenopathy, hepatomegaly/splenomegaly, or serositis, as defined by the ILAR criteria 5, 4
Enthesitis-related arthritis is diagnosed based on arthritis and enthesitis, or arthritis or enthesitis with at least two of: sacroiliac joint tenderness/inflammatory back pain, HLA-B27 positivity, family history of HLA-B27-associated disease, anterior uveitis, or onset in males over 6 years, according to the ILAR criteria 2, 3
Psoriatic arthritis is characterized by arthritis and psoriasis, or arthritis with at least two of: dactylitis, nail pitting/onycholysis, or psoriasis in a first-degree relative, as defined by the ILAR criteria 2, 3

Laboratory tests, including complete blood count with differential, ESR, CRP, ANA, RF, liver function tests, and albumin, are recommended to confirm JIA diagnosis and exclude other conditions, as suggested by the American College of Rheumatology 6, 1
Ultrasound and MRI are superior to clinical examination for detecting joint inflammation, and are recommended for imaging evaluation, according to the European League Against Rheumatism 7
Conventional radiography can be used to detect structural damage but may be normal in early disease, as noted by the American College of Rheumatology 6, 7
MRI is particularly valuable for detecting inflammation in temporomandibular joints and axial involvement, as recommended by the European League Against Rheumatism 7

Infectious arthritis (bacterial, viral, fungal, mycobacterial) must be ruled out in the diagnosis of JIA, as recommended by the American College of Rheumatology 6
Malignancy (leukemia, lymphoma) must be excluded in the diagnosis of JIA, according to the American College of Rheumatology 6
Other rheumatic diseases (SLE, vasculitis) must be ruled out in the diagnosis of JIA, as recommended by the American College of Rheumatology 6

Elevated ferritin and decreased glycosylated ferritin may support diagnosis in systemic JIA, as noted by the European League Against Rheumatism 6, 4
Intercarpal and carpometacarpal joint space narrowing with potential pericapitate ankylosis may develop in some patients, as reported by the American College of Rheumatology 6