Danbot: Strip excess bold

2026-03-22T09:32:38Z

Strip excess bold

Ostermayer: Ostermayer moved page Systemic Juvenile Idiopathic Arthritis (sJIA) to Systemic juvenile idiopathic arthritis (sJIA)

2026-03-09T19:43:37Z

Ostermayer moved page Systemic Juvenile Idiopathic Arthritis (sJIA) to Systemic juvenile idiopathic arthritis (sJIA)

← Older revision	Revision as of 19:43, 9 March 2026
(No difference)

Ostermayer: Created page with "==Background== Systemic juvenile idiopathic arthritis (sJIA) is also known as '''Still's disease''' (the adult form is adult-onset Still's disease) An '''autoinflammatory''' disease (driven by innate immune system and IL-1/IL-6), distinct from other forms of JIA which are autoimmuneJuvenile Idiopathic Arthritis. StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024. *Children <16 years; accounts for 10-20% of all JIA but..."

2026-03-09T19:41:59Z

Created page with "==Background== *Systemic juvenile idiopathic arthritis (sJIA) is also known as '''Still's disease''' (the adult form is adult-onset Still's disease) *An '''autoinflammatory''' disease (driven by innate immune system and IL-1/IL-6), distinct from other forms of JIA which are autoimmune<ref name="StatPearls">Juvenile Idiopathic Arthritis. StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024.</ref> *Children <16 years; accounts for 10-20% of all JIA but..."

New page

==Background==
*Systemic juvenile idiopathic arthritis (sJIA) is also known as '''Still's disease''' (the adult form is adult-onset Still's disease)
*An '''autoinflammatory''' disease (driven by innate immune system and IL-1/IL-6), distinct from other forms of JIA which are autoimmune<ref name="StatPearls">Juvenile Idiopathic Arthritis. StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024.</ref>
*Children <16 years; accounts for 10-20% of all JIA but contributes approximately two-thirds of JIA-related mortality<ref name="Behrens2008">Behrens EM, Beukelman T, Paessler M, Cron RQ. Occult macrophage activation syndrome in patients with systemic juvenile idiopathic arthritis. J Rheumatol. 2007;34(5):1133-8.</ref>
*Peak onset age 1-5 years; equal sex distribution (unlike other JIA subtypes)
*Most important differential diagnosis in a child presenting with prolonged [[fever of unknown origin]]
*sJIA is a diagnosis of exclusion — '''must rule out infection and malignancy first'''

===ILAR Classification Criteria===
Arthritis in ≥1 joint with, or preceded by, fever of ≥2 weeks duration that is documented to be '''quotidian''' (daily) for ≥3 days, '''PLUS''' ≥1 of the following:<ref name="ILAR">Petty RE, Southwood TR, Manners P, et al. International League of Associations for Rheumatology classification of juvenile idiopathic arthritis: second revision, Edmonton, 2001. J Rheumatol. 2004;31(2):390-2.</ref>
#Evanescent (nonfixed) erythematous rash
#Generalized [[lymphadenopathy]]
#[[Hepatomegaly]] and/or [[splenomegaly]]
#Serositis ([[pericarditis]], [[pleuritis]], or peritonitis)

''Exclusions: Psoriasis in patient or first-degree relative, arthritis in HLA-B27+ male with onset after age 6, [[ankylosing spondylitis]]/ERA/sacroiliitis with IBD/reactive arthritis/acute anterior uveitis in first-degree relative, positive IgM RF on ≥2 occasions ≥3 months apart''

==Clinical Features==
===Fever===
*'''Quotidian''' (daily spiking) pattern: temperature spikes to ≥39°C (102.2°F), typically 1-2 times daily (often late afternoon/evening), with return to '''normal or below normal''' baseline between spikes<ref name="Raj2024">Spoorthy Raj DR, Suma Balan. Systemic Juvenile Idiopathic Arthritis: The Challenges and Opportunities. Indian J Rheumatol. 2024.</ref>
*Child may appear '''profoundly ill''' during fever spikes and '''remarkably well''' between them — this pattern is highly suggestive
*The classic quotidian pattern is observed in only ~37% of patients; atypical fever patterns are common<ref name="Raj2024"/>
*Duration ≥2 weeks by definition
*'''ED Pearl:''' Evolution from intermittent spiking fever to '''continuous high fever''' should raise concern for [[macrophage activation syndrome]] (MAS)

===Rash===
*'''Evanescent''' (comes and goes), salmon-pink, macular or maculopapular
*Appears during fever spikes, resolves with defervescence — '''may be absent when the child is afebrile in the ED'''
*Trunk, proximal extremities, axillae, neck; spares face
*Non-pruritic, non-fixed, leaves no residual scarring or pigmentation
*'''Koebner phenomenon:''' rash may appear at sites of skin scratching or pressure<ref name="Raj2024"/>
*May be difficult to appreciate in '''dark-skinned children''' — examine during active fever

===Arthritis===
*May be oligoarticular or polyarticular; wrists, knees, and ankles most commonly affected
*Arthritis '''may be delayed''' — systemic features can precede joint involvement by weeks to months
*Cervical spine and temporomandibular joint involvement more common in sJIA than other JIA subtypes

===Other Features===
*[[Hepatomegaly|Hepatosplenomegaly]]
*Generalized [[lymphadenopathy]]
*'''Serositis:''' [[pericardial effusion]] (most common serosal involvement), [[pleural effusion]], peritonitis
*[[Myalgia]], severe malaise, weight loss, irritability
*Growth retardation (chronic disease)

===Macrophage Activation Syndrome (MAS)===
'''''The most life-threatening complication of sJIA. Occurs in ~10% overtly, up to 30% subclinically.'''''<ref name="Ravelli2012">Ravelli A, Minoia F, Davì S, et al. 2016 Classification Criteria for Macrophage Activation Syndrome Complicating Systemic Juvenile Idiopathic Arthritis. Arthritis Rheumatol. 2016;68(3):566-76.</ref>
*A form of secondary [[hemophagocytic lymphohistiocytosis]] (HLH) — massive cytokine storm
*'''Triggers:''' viral infections, medication changes, disease flares
*'''Clinical red flags for MAS:'''
**'''Change in fever pattern''' from intermittent to '''continuous'''
**Worsening despite treatment, or rapid deterioration
**New or worsening [[hepatomegaly]]
**Hemorrhagic manifestations (bruising, mucosal bleeding)
**Encephalopathy, [[altered mental status]]
**'''Paradoxical drop in ESR''' (due to fibrinogen consumption) while [[ferritin]] is markedly elevated
*'''Lab hallmarks of MAS:'''
**'''Hyperferritinemia''' (often >10,000 ng/mL; markedly disproportionate to other acute phase reactants)
**↓ Fibrinogen (consumption)
**↓ Platelets (falling trend, even if still "normal")
**↓ WBC (falling trend)
**↑ AST/ALT (liver involvement)
**↑ Triglycerides
**↑ LDH
**↑ D-dimer / ↓ ESR (paradoxical — ESR drops as fibrinogen is consumed)
*'''ED Pearl:''' A falling platelet count, falling ESR, or rising ferritin in a child with sJIA should be considered MAS until proven otherwise and warrants emergent rheumatology and/or hematology consultation

==Differential Diagnosis==
''sJIA is a diagnosis of exclusion. The following must be considered before attributing findings to sJIA:''

===Critical to Exclude===
*'''[[Leukemia]]/[[lymphoma]]''' — most important mimicker; can present with fever, arthralgia, hepatosplenomegaly, lymphadenopathy, and cytopenias
*'''[[Sepsis (Main)|Sepsis]]/bacteremia''' — especially [[endocarditis]]
*'''[[Kawasaki disease]]''' — prolonged fever, rash, lymphadenopathy (but typically <5 days fever at presentation, and specific mucocutaneous criteria)
*'''[[Neuroblastoma]]''' and other solid tumors

===Other Differential===
*[[Acute rheumatic fever]]
*Viral infections ([[EBV]], [[CMV]], parvovirus B19, [[HIV]])
*[[Lyme disease]]
*Reactive arthritis
*[[Systemic lupus erythematosus]]
*[[Inflammatory bowel disease]] with extraintestinal manifestations
*PFAPA syndrome (periodic fever, aphthous stomatitis, pharyngitis, adenitis)
*Autoinflammatory syndromes (familial Mediterranean fever, TRAPS, etc.)
*[[Polyarteritis nodosa]]
*Castleman disease

{{Pediatric hip DDX}}
{{Differential Diagnosis Polyarthritis}}

==Evaluation==
===Workup===
*'''CBC with differential:'''
**Leukocytosis (often marked; WBC >15,000-50,000+; sometimes leukemoid reaction)
**Anemia (hypochromic, microcytic — anemia of chronic disease)
**Thrombocytosis (reactive) — '''a falling platelet count suggests MAS'''
*'''ESR, [[CRP]]:''' markedly elevated; '''paradoxical drop in ESR with rising CRP suggests MAS'''
*'''[[Ferritin]]:''' often very elevated in active sJIA (typically >500 ng/mL); '''ferritin >10,000 ng/mL strongly suggests MAS'''<ref name="Ravelli2012"/>
*'''Fibrinogen:''' normal or elevated in active sJIA; '''falling fibrinogen suggests MAS'''
*'''[[LFTs]]:''' may be elevated; transaminitis suggests MAS or hepatic involvement
*'''LDH, triglycerides, D-dimer:''' to screen for MAS
*'''[[Blood culture]]:''' mandatory to exclude bacteremia/sepsis
*'''Peripheral blood smear:''' to evaluate for blasts (leukemia) and hemophagocytes
*'''Coagulation studies''' (PT/PTT): may be prolonged in MAS/DIC
*Consider: [[procalcitonin]] (may help differentiate infection from sJIA flare, though not definitive), [[uric acid]], [[urinalysis]]

===Imaging===
*'''[[CXR]]:''' evaluate for [[pleural effusion]], [[pericardial effusion]], or [[pneumonia]]
*'''[[Echocardiography]]:''' if concern for [[pericardial effusion]] or [[myocarditis]]
*'''Joint imaging:''' [[ultrasound]] or X-ray of affected joints to assess for effusion; may help distinguish from [[septic arthritis]]

===Diagnosis===
*Clinical diagnosis based on ILAR criteria (see Background) after '''exclusion of infection and malignancy'''
*'''[[Arthrocentesis]]''' may be needed to exclude [[septic arthritis]] — especially if monoarticular presentation
*'''Bone marrow biopsy''' may be required to exclude leukemia if clinical concern exists, particularly before starting corticosteroids (which can mask leukemia)
*ANA and RF are typically '''negative''' in sJIA (if positive, consider other diagnoses)
*No single diagnostic test is confirmatory — the diagnosis rests on the combination of clinical features and exclusion of mimickers

==Management==
''Management in the ED is focused on stabilization, diagnostic workup, and rheumatology consultation. Definitive treatment is guided by pediatric rheumatology.''

===Acute ED Management===
*'''Hemodynamic stabilization''' if MAS or sepsis is suspected
*Empiric '''[[antibiotics]]''' until sepsis/bacterial infection can be excluded (these patients often appear septic)
*'''[[NSAIDs]]''' for fever, pain, and mild-moderate disease:
**[[Naproxen]] 10-15 mg/kg/day divided BID (most commonly used NSAID in sJIA)
**[[Ibuprofen]] 30-40 mg/kg/day divided TID-QID
*'''[[Corticosteroids]]''' may be initiated if:
**Diagnosis is certain (infection and malignancy excluded)
**Severe systemic illness, [[pericarditis]], or MAS
**Typically [[methylprednisolone]] IV pulse (30 mg/kg, max 1g) for severe disease or MAS, or [[prednisone]] 1-2 mg/kg/day PO for moderate disease
**'''Do not start steroids before obtaining a peripheral smear and ideally a bone marrow biopsy if leukemia has not been excluded'''<ref name="StatPearls"/>
*If MAS suspected: emergent rheumatology and/or hematology consultation; high-dose IV corticosteroids are first-line; may require [[cyclosporine]] or anakinra

===Definitive Therapy (Rheumatology-Directed)===
*'''IL-1 inhibitors''' ([[anakinra]], canakinumab) and '''IL-6 inhibitors''' ([[tocilizumab]]) are first-line biologic agents for moderate-severe sJIA<ref name="Ringold2023">Ringold S, Angeles-Han ST, Engel ME, et al. 2019 American College of Rheumatology/Arthritis Foundation Guideline for the Treatment of Juvenile Idiopathic Arthritis: Therapeutic Approaches for Systemic Juvenile Idiopathic Arthritis. Arthritis Care Res. 2022;74(4):521-533.</ref>
*Goal is early aggressive therapy to achieve remission and minimize corticosteroid exposure
*'''Anakinra''' (IL-1 receptor antagonist) may be started in the ED or inpatient setting by rheumatology for severe/refractory disease or MAS

===Consults===
*'''Pediatric rheumatology:''' All patients with suspected sJIA
*'''Pediatric hematology/oncology:''' If leukemia/malignancy is on the differential, or if MAS is suspected
*'''Cardiology:''' If significant [[pericardial effusion]] or concern for [[cardiac tamponade]]

==Disposition==
*'''Admit''' — nearly all patients with suspected new-onset sJIA require admission for:
**Diagnostic workup to exclude infection and malignancy
**Monitoring for MAS (which can develop at any point)
**Initiation of treatment
**Rheumatology consultation
*'''ICU admission''' if:
**MAS with hemodynamic instability, coagulopathy, or organ dysfunction
**Significant [[pericardial effusion]] with hemodynamic compromise
**Respiratory distress from [[pleural effusion]] or pulmonary disease

==See Also==
*[[Hip Pain (Peds)]]
*[[Kawasaki disease]]
*[[Septic arthritis]]
*[[Leukemia]]
*[[Pericardial effusion and tamponade]]
*[[Acute rheumatic fever]]
*[[Fever of unknown origin]]

==External Links==
*[https://www.arthritis.org/diseases/systemic-juvenile-idiopathic-arthritis Arthritis Foundation - Systemic JIA Overview]
*[https://www.ncbi.nlm.nih.gov/books/NBK554605/ StatPearls - Juvenile Idiopathic Arthritis]

==References==
{{reflist|2}}

[[Category:Rheumatology]]
[[Category:Pediatrics]]

Systemic juvenile idiopathic arthritis (sJIA) - Revision history

Danbot: Strip excess bold

Ostermayer: Ostermayer moved page Systemic Juvenile Idiopathic Arthritis (sJIA) to Systemic juvenile idiopathic arthritis (sJIA)