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Last reviewed: 16 Mar 2025
Last updated: 14 Sep 2023

Summary

Definition

History and exam

Key diagnostic factors

  • fever ≥39.0°C (≥102.2°F)
  • arthralgia
  • arthritis
  • salmon-coloured maculopapular skin rash

Other diagnostic factors

  • dermographic urticaria
  • sore throat
  • myalgia
  • lymphadenopathy
  • pleuritis
  • splenomegaly
  • hepatomegaly
  • pericarditis
  • myocarditis
  • signs of macrophage activation syndrome (MAS)

Risk factors

  • female sex
  • young adult age
  • preceding infection (e.g., with cytomegalovirus, Epstein-Barr virus, rubella, Mycoplasma)

Diagnostic investigations

1st investigations to order

  • FBC
  • renal panel
  • C-reactive protein (CRP)
  • erythrocyte sedimentation rate (ESR)
  • liver function tests
  • procalcitonin
  • blood cultures
  • chest x-ray
  • renal and liver ultrasound scan
  • echocardiogram
  • ECG

Investigations to consider

  • cardiac enzymes
  • cardiac MRI
  • serum ferritin
  • glycosylated ferritin
  • further tests as part of full septic screen
  • further tests as part of autoimmune/rheumatological screen
  • fluorodeoxyglucose (FDG)-positron emission tomography (PET) whole-body scan
  • whole-body CT scan
  • bone marrow biopsy
  • lymph node biopsy
  • empirical corticosteroids
  • autoinflammatory gene profiling

Emerging tests

  • cytokine profiles
  • serum S100A12; serum calprotectin (S100A8/S100A9 dimer)
  • HLA genotyping

Treatment algorithm

Contributors

Authors

Sinisa Savic, MRCP, FRCPath, PhD

Associate Professor (Clinical)

Leeds Institute of Rheumatic and Musculoskeletal Medicine

Consultant

Department of Clinical Immunology and Allergy

St James’s University Hospital

Clinical Lead for Allergy and Immunology

The Leeds Teaching Hospitals NHS Trust

Leeds

UK

Disclosures

SS has received payment for consulting services from Novartis, Takeda, SOBI, BioCryst, CSL Behring, and Kalvista. Speaking/educational events Takeda, Novartis, SOBI, and SCL Behring. Research grants SOBI and CSL Behring.

Adam Al-Hakim, BMBS, MRCP, BMedSci

Specialty Registrar in Clinical Immunology and Allergy

St James’s University Hospital

The Leeds Teaching Hospitals NHS Trust

Leeds

UK

Disclosures

AA declares that he has no competing interests.

Peer reviewers

Sreelakshmi Panginikkod, MD, FACP, FACR

Assistant Professor in Rheumatology and Associate Program Director for Rheumatology

Tufts University School of Medicine

Boston

MA

Disclosures

SP declares that she has no competing interests

James Galloway, MBChB, MSc, PhD, FRCP

Professor of Rheumatology

King’s College London

Honorary Consultant Rheumatologist

King’s College Hospital

London

UK

Disclosures

JG declares that he has no competing interests.

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