Differential Diagnosis Classification
Juvenile idiopathic arthritis requires meticulous clinical exclusion of other diseases.
Table 1: Differential Diagnosis Of Childhood Arthritis
| Disease Category | Specific Conditions |
|---|---|
| Infectious Diseases | Septic arthritis, viral arthritis (rubella, parvovirus B19, Epstein-Barr virus, hepatitis B), Lyme disease, osteomyelitis, endocarditis. |
| Reactive And Post-Infectious | Acute rheumatic fever, reactive arthritis (enteric or urogenital triggers), transient synovitis of the hip. |
| Rheumatic And Autoimmune | Systemic lupus erythematosus, juvenile dermatomyositis, scleroderma, IgA vasculitis, Kawasaki disease, sarcoidosis, mixed connective tissue disease. |
| Neoplastic Disorders | Leukemia, neuroblastoma, lymphoma, bone tumors. |
| Orthopedic And Mechanical | Trauma, growing pains, hypermobility syndromes, Legg-Calve-Perthes disease, slipped capital femoral epiphysis, chondrolysis. |
| Autoinflammatory Syndromes | Periodic fever syndromes, macrophage activation syndrome, familial Mediterranean fever. |
| Immunodeficiencies | Hypogammaglobulinemia, IgA deficiency, common variable immunodeficiency. |
| Congenital And Metabolic | Gout, mucopolysaccharidoses, thyroid disease, scurvy, skeletal dysplasias. |
Differentiating Features
- Acute rheumatic fever causes exquisitely painful, migratory polyarthritis.
- Malignancy exhibits nocturnal bone pain awakening children from sleep.
- Malignancy demonstrates disproportionate pain relative to physical findings.
- Leukemia presents with leukopenia, low-normal platelets, and high erythrocyte sedimentation rate (ESR).
- Bone marrow examination remains mandatory confirming malignant infiltration.
- Transient synovitis causes acute hip pain following viral infections.
- Septic arthritis presents as an acute, painful, erythematous, hot single joint.
- Synovial fluid aspiration excludes septic arthritis definitively.
Management Principles
Treatment Goals
- Achieve complete disease remission.
- Prevent or halt joint damage and deformities.
- Foster normal psychosocial and physical growth.
Pharmacological Interventions
Table 2: Pharmacotherapy Agents And Indications
| Drug Class | Specific Agents | Pediatric Dosage | Clinical Indications And Notes |
|---|---|---|---|
| Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) | Naproxen | 10–20 mg/kg/day PO divided q12h (Max: 1000 mg/day) | Initial symptomatic therapy relieving pain and stiffness. |
| Ibuprofen | 30–40 mg/kg/day PO divided q6-8h (Max: 2400 mg/day) | Initial symptomatic therapy relieving pain and stiffness. | |
| Meloxicam | 0.125 mg/kg PO once daily (Max: 7.5 mg/day) | Initial symptomatic therapy relieving pain and stiffness. | |
| Glucocorticoids | Triamcinolone hexacetonide | 1 mg/kg per large joint (knee/hip); 0.5 mg/kg per small joint (Max: 40 mg per joint) | Intra-articular injection preferred for oligoarthritis. |
| Prednisolone | 0.5–2 mg/kg/day PO (Max: 60 mg/day); use lowest effective dose for bridge | Systemic route serves as bridge therapy or controls severe systemic JIA. | |
| Conventional Synthetic DMARDs | Methotrexate | 10–15 mg/m²/week SC or PO once weekly (Max: 25 mg/week) | Anchors treatment for polyarthritis and extended oligoarthritis. |
| Sulfasalazine | 30–50 mg/kg/day PO divided q12h; start low and titrate upward (Max: 2000 mg/day) | Targets enthesitis-related arthritis. | |
| Leflunomide | Weight-based: <40 kg: 10 mg every other day or daily; >40 kg: 10–20 mg PO once daily | Alternate conventional DMARD option. | |
| Biologic DMARDs (Anti-TNF) | Etanercept | 0.8 mg/kg/week SC once weekly (Max: 50 mg/week) | Targets polyarthritis refractory to methotrexate. |
| Adalimumab | Weight-based: 10 to <15 kg: 10 mg; 15 to <30 kg: 20 mg; ≥30 kg: 40 mg SC every 2 weeks | Preferred treating associated uveitis. | |
| Infliximab | 6 mg/kg IV infusion at weeks 0, 2, 6, then every 8 weeks | Used off-label for refractory polyarticular JIA/uveitis. | |
| Golimumab | 30 mg/m² SC every 4 weeks (Max: 50 mg per dose) | Treats polyarticular JIA. | |
| Biologic DMARDs (Anti-IL-1) | Anakinra | 1–2 mg/kg/day SC once daily (Max: 100 mg/day); up to 4 mg/kg/day in MAS | Highly effective treating systemic JIA. |
| Canakinumab | Weight-based: ≤75 kg: 4 mg/kg SC every 4 weeks; >75 kg: 300 mg SC every 4 weeks | Highly effective treating systemic JIA. | |
| Biologic DMARDs (Anti-IL-6) | Tocilizumab | sJIA: <30 kg: 12 mg/kg IV q2w; ≥30 kg: 8 mg/kg IV q2w pJIA: <30 kg: 10 mg/kg IV q4w; ≥30 kg: 8 mg/kg IV q4w | Manages systemic JIA and macrophage activation syndrome. |
| T-Cell Modulators | Abatacept | IV: <75 kg: 10 mg/kg q4w SC: 10 to <25 kg: 50 mg/week; 25 to <50 kg: 87.5 mg/week; ≥50 kg: 125 mg/week | Inhibits T-cell activation treating polyarticular JIA. |
| Small Molecules (JAK Inhibitors) | Tofacitinib | Oral Solution/Tablet: <40 kg: 5 mg (5 mL) PO q12h; ≥40 kg: 5 mg tablet PO q12h | Treats polyarticular JIA targeting intracellular signaling. |
Subtype-Specific Approach
- Oligoarthritis management utilizes NSAIDs or intra-articular corticosteroids initially.
- Methotrexate addition indicated for extended oligoarthritis or refractory disease.
- Polyarthritis demands early aggressive therapy utilizing methotrexate.
- Biologic tumor necrosis factor (TNF) antagonists added upon methotrexate failure.
- Systemic JIA therapy utilizes corticosteroids alongside interleukin-1 or interleukin-6 antagonists.
- Enthesitis-related arthritis responds to NSAIDs, sulfasalazine, and TNF inhibitors.
- Macrophage activation syndrome requires pulse intravenous methylprednisolone and cyclosporine.
Multidisciplinary Rehabilitation
- Physical therapy prevents fixed flexion contractures and maintains joint mobility.
- Occupational therapy provides customized splints facilitating activities of daily living.
- Routine slit-lamp ophthalmologic screening mandatory detecting asymptomatic uveitis.
- Nutritionist consultation addresses growth failure and osteopenia secondary to chronic inflammation.
- Psychosocial support essential addressing depression, school absenteeism, and chronic pain impact.