Bear paw sign (kidney)

The bear paw sign refers to the cross-sectional appearance of the kidney affected by xanthogranulomatous pyelonephritis. There is a radial arrangement of multiple, low attenuation rounded spaces representing dilated calyces, surrounded by thin renal parenchyma that has higher attenuation or contrast enhancement, mimicking the appearance of the dark toe pads on a polar bear's paw.

Inspired signs
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Article information

rID: 9946
System: Urogenital
Section: Signs
Synonyms or Alternate Spellings:
  • Bear paw sign (xanthogranulomatous pyelonephritis)

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Cases and figures

  • Case 1: bear paw sign
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  • Polar bear (photo)
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  • Case 2: even seen on non-contrast CT
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  • Case 3
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  • Case 4
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