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Yamaguchi criteria

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Yamaguchi Criteria — Adult-Onset Still's Disease (AOSD)

The Yamaguchi criteria (1992) are the standard classification criteria for Adult-Onset Still's Disease. They require at least 5 criteria, of which at least 2 must be major, with no exclusion criteria met.

Major Criteria

  1. Fever ≥39°C (102.2°F) lasting 1 week or more
  2. Arthralgia lasting 2 weeks or more
  3. Typical skin rash — maculopapular, non-pruritic, salmon-pink rash occurring with fever spikes
  4. Leukocytosis ≥10,000/mm³ with polymorphonuclear neutrophil count ≥80%

Minor Criteria

  1. Pharyngitis or sore throat
  2. Lymphadenopathy and/or splenomegaly
  3. Liver dysfunction (elevated transaminases or LDH with negative serology)
  4. Negative ANA and RF

Exclusion Criteria (all must be absent)

  • Infections (especially sepsis, infectious mononucleosis)
  • Malignancies (especially lymphoma)
  • Other rheumatic diseases (especially polyarteritis nodosa, rheumatoid vasculitis with extra-articular features)

Scoring Rule

≥5 criteria total, with ≥2 being major + no exclusion criteria → AOSD diagnosis

Comparison: Fautrel Criteria (Alternative)

The Fautrel criteria are a more recent alternative and differ in key ways:
  • Includes glycosylated ferritin ≤20% as a major criterion (more specific for AOSD)
  • Does not require exclusion criteria
  • Met by: 4 major criteria, or 3 major + 2 minor
FeatureYamaguchiFautrel
Glycosylated ferritinNot includedMajor criterion (≤20%)
Exclusion criteria requiredYesNo
Threshold≥5 (≥2 major)4 major OR 3 major + 2 minor

Clinical Context

AOSD is a systemic autoinflammatory disorder. The diagnosis remains difficult because it requires excluding other causes of fever of unknown origin — infections, malignancies (50% hematologic, notably lymphoma), and other rheumatic diseases. Elevated ferritin (often markedly so) is a hallmark lab finding, and leukocytosis with neutrophil predominance is present in ~85% of patients.
— Fitzpatrick's Dermatology, Table 66-5
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