Radiopaedia 2021 UPDATE Conference-only registration is now closed. Late registration for All-Access Pass and Free Country Pass holders ends this Friday - LEARN MORE

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

Article information

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

ADVERTISEMENT: Supporters see fewer/no ads

Cases and figures

  • Case 1: bear paw sign
    Drag here to reorder.
  • Polar bear (photo)
    Drag here to reorder.
  • Case 2: even seen on non-contrast CT
    Drag here to reorder.
  • Case 3
    Drag here to reorder.
  • Case 4
    Drag here to reorder.
  • Updating… Please wait.

     Unable to process the form. Check for errors and try again.

     Thank you for updating your details.