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  • Age: 52
  • Sex: Male
  • Medical history:
    • recurrent knee pain
    • self-medication with NSAR
    • planned for surgical knee replacement

    • construction worker 
    • long trips from home to work abroad
    • seldomly time to visit the physician
  • Clinical findings:
    • Swollen knees, feet, elbows, and wrists
    • CRP 30 mg/l
    • Elevated ESR

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1: Construction worker with knee pain

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Erosive and tophaceous gouty arthritis

The patient presented with knee pain and could not see the doctor regularly from his work abroad. In addition, working at construction sites, he could not eat healthily often. The orthopaedic surgeon attributed his pain to osteoarthritis based on the loss of joint space in radiography. 

The case shows that gout should always be a differential diagnosis, especially in male patients. Gouty tophi can be hard to spot in conventional radiographs. The soft-tissue depositions can be hard to characterise by MRI sequences. Specific imaging modalities are ultrasound (double contour sign, tophi), dual-energy-CT (tophus) and radiography when erosions show specific morphology. All of those imaging modalities can confirm the diagnosis of gouty arthritis. 

The standard of reference for diagnosis is joint aspiration with the proof of negatively birefringent crystals. However, this somewhat invasive procedure is seldomly performed in clinical practice. Therefore, the diagnosis is often based on a combination of clinical and imaging features. The following imaging signs to help: 

  • Specific erosions (punched out character, overhanging edges, extraarticular)
  • Double contour sign (arthrosonography only)
  • Tophus (radiography, CT, MRI and arthrosonography)

DECT can not only detect and characterise tophi but also quantify the uric acid burden and help to follow up the patient under therapy.