Can you spot the odd abnormality in this case?

You are shown a sagittal T1 (image 1) and a sagittal proton density fat suppression water-weighted image (image 2) of the knee of a 61-year-old.

  • What are the arrows indicating?
  • What other abnormality is odd about the patella?

Sagittal T1

Sagittal T2

  • The arrows point to an area of linear penetrating upper pole class 4 chondromalacia.
  • What is odd about the patella is that the medullary space is subtly but definitely swollen on the water-weighted image. The swelling is diffuse and far greater than that expected for a simple, thin penetrating erosion.
  • Follow-up question: Other explanations that may account for such swelling might include:
    • a. Unrecognized trauma or minor fall with contusion
    • b. Reactive swelling from concomitant CPPD within the erosion
    • c. Gout
  • Answer: C. Gout
  • ProScan Pearl: Don’t try to make a finding into something it is not. In other words, with no history of trauma, trauma is an impossible choice. The edema as a simple chondromalacic reaction could not be explained by this one erosion. For more case review, check out MRI Online.
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