Epidemiology

• Genetic predisposition and association with HLA-B27 (see “Seronegative spondyloarthritis”)
• Commonly affects young men

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Etiology

Postinfectious autoimmune disorder

• Posturethritis: after infection with Chlamydia (common) or Ureaplasma urealyticum
• Postenteritis: after infection with Shigella, Yersinia, Salmonella, or Campylobacter

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Pathophysiology

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Clinical features

Tip

The clinical manifestations are caused by immune complexes involving bacterial antigens. However, it does not represent disseminated infection, and joint aspirates are sterile (ie, it is a ‘reactive’ not infectious arthritis).

• Recent UTI or GI infections
• Musculoskeletal symptoms
  • Oligoarthritis (sometimes polyarthritis)
    • Acute onset
    • Often asymmetrical with a migratory character
    • Occurs predominantly in the lower extremities
  • Sacroiliitis
  • Enthesitis
  • Dactylitis
• Extra‑articular symptoms
  • Conjunctivitis, iritis, episcleritis, or keratitis
  • Dermatologic manifestations
  • Balanitis circinata: skin lesions of the glans resembling psoriasis
  • Keratoderma blenorrhagicum: hyperkeratinization of the palms and soles
  • Urethritis
• Symptoms from preceding infection
  • Diarrhea
  • Urogenital tract symptoms (dysuria, pelvic pain, prostatitis)

Mnemonic

Classic triad of reactive arthritis (seen in approximately one-third of affected individuals): “can’t see (conjunctivitis), can’t pee (urethritis), can’t climb a tree (arthritis)”.

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Differential Diagnostics

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Treatment

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Prognosis

• Resolves spontaneously within a year
• High rate of recurrence