What are the presentations of juvenile idiopathic arthritis (JIA)?

Clinical Presentations of Juvenile Idiopathic Arthritis

Juvenile idiopathic arthritis presents as chronic arthritis (joint swelling or limitation of motion with pain, heat, or tenderness) beginning before age 16 years, persisting for at least 6 weeks, after excluding other known conditions. 1, 2

Core Diagnostic Features

The diagnosis requires three essential elements 2, 3:

• Arthritis onset before 16 years of age 2
• Symptoms persisting for at least 6 weeks 2, 3
• Exclusion of infectious, oncologic, autoimmune, and other rheumatic diseases 2, 4

Clinical Subtypes and Their Presentations

Systemic JIA (10-20% of cases)

Systemic JIA presents with arthritis accompanied by daily spiking fever for at least 2 weeks, plus one or more of the following: 5, 2, 4

• Evanescent (salmon-colored) rash 2, 4
• Generalized lymphadenopathy 2, 4
• Hepatomegaly and/or splenomegaly 2, 4
• Serositis (pericarditis, pleuritis, peritonitis) 2, 4

The fever pattern is characteristically quotidian (daily spikes), and the rash is typically migratory and non-pruritic 4. Macrophage activation syndrome is a serious and potentially fatal complication requiring prompt recognition, presenting with persistent (rather than quotidian) fever, cytopenias, falling ESR, hypertriglyceridemia, hypofibrinogenemia, hemophagocytosis, transaminitis, coagulopathy, organomegaly, hyperferritinemia, or CNS dysfunction 6, 4.

Polyarticular JIA (≥5 joints involved)

Polyarticular JIA affects 5 or more joints and is subdivided into RF-positive and RF-negative subtypes 1, 5:

• RF-positive polyarthritis resembles adult rheumatoid arthritis, affects small joints symmetrically, and indicates poor prognosis 1, 5
• RF-negative polyarthritis is more common and has variable joint distribution 1, 5
• Symmetric disease pattern suggests worse prognosis 1
• Involvement of high-risk joints (cervical spine, wrist, hip, temporomandibular joint) indicates poor prognosis 1, 5

Oligoarticular JIA (≤4 joints involved)

Oligoarticular JIA affects 4 or fewer joints and is typically RF-negative 5:

• Most common subtype in young children 5
• High risk for chronic anterior uveitis, particularly in ANA-positive patients with early-onset disease 6, 5
• May extend to involve more joints over time (extended oligoarthritis) 5

Enthesitis-Related Arthritis

Diagnosed by arthritis and enthesitis, or arthritis/enthesitis with at least 2 of the following 5, 2:

• Sacroiliac joint tenderness or inflammatory back pain 5, 2
• HLA-B27 positivity 5, 2
• Family history of HLA-B27-associated disease 5, 2
• Anterior uveitis (typically acute, not chronic) 5, 2
• Male onset after age 6 years 5, 2

Psoriatic Arthritis

Characterized by arthritis with psoriasis, or arthritis with at least 2 of 5, 2:

• Dactylitis (sausage digits) 5, 2
• Nail pitting or onycholysis 5, 2
• Psoriasis in a first-degree relative 5, 2

Extra-Articular Manifestations

Ocular Involvement

Chronic anterior uveitis most commonly develops between ages 3-7 years and is typically asymptomatic initially 6:

• ANA positivity, oligoarthritis, and early arthritis onset are predominant risk factors 6
• Severe inflammation may cause symptomatic pain, redness, and pupil distortion 6
• All patients with JIA require screening for uveitis according to contemporary protocols 6

Orofacial Manifestations

Temporomandibular joint (TMJ) arthritis causes dentofacial deformities 6:

• Micrognathia (small jaw) from impaired mandibular growth 6
• Facial asymmetry 6
• Periodontal disease (gingival inflammation, periodontitis) is more prevalent in JIA patients compared to healthy controls 6

Laboratory and Imaging Findings

Essential laboratory evaluation includes 5, 2:

• CBC with differential, ESR, CRP (elevated inflammatory markers support diagnosis) 5, 2
• ANA, RF, anti-CCP antibodies (define subtypes and prognosis) 1, 5, 2
• Liver function tests and albumin 5, 2
• HLA-B27 (for enthesitis-related arthritis) 5, 2
• Elevated ferritin with decreased glycosylated ferritin supports systemic JIA diagnosis 5, 2

Imaging modalities 5, 2:

• Ultrasound and MRI are superior to clinical examination for detecting joint inflammation 5, 2
• MRI is particularly valuable for detecting TMJ and axial inflammation 5, 2
• Conventional radiography may be normal in early disease but can detect structural damage 5, 2

Poor Prognostic Indicators

Features predicting worse outcomes include 1, 5:

• Positive RF or anti-CCP antibodies 1, 5
• Symmetric disease distribution 1
• Involvement of cervical spine, wrist, hip, or TMJ 1, 5
• Elevated inflammatory markers 1
• Early radiographic changes 1
• Greater severity or extent of arthritis at presentation 1

Clinical Course Patterns

The disease follows a fluctuating pattern of active and inactive periods 7:

• The percentage of time with active disease in the first 2 years predicts the clinical course in subsequent years 7
• Different subtypes show significantly different percentages of time with active disease 7
• Wide variation in cumulative disease activity occurs within each subtype 7