Xanthogranulomatous pyelonephritis

Case contributed by Dr Ian Bickle

Presentation

Recurrent renal stone disease, admitted with flank pain and fever

Patient Data

Age: 50 years
Gender: Female

Right-sided staghorn calculus.

Ultrasound

Large right staghorn calculus, with ultrasound demonstrating dilated fluid filled spaces, without hydronephrosis. 

'Bear's paw' appearance of dilated fluid filled spaces in the kidney with a central staghorn calculus.

Large right staghorn calculus, with ultrasound demonstrating dilated fluid filled spaces, without hydronephrosis.  This is elegantly shown on CT with an enlarged right kidney, with a bear's paw appearance of xanthogranulomatous pyelonephritis (XPN) with a small perinephric collection.

Case Discussion

Classical appearances of XPN with a bear paw sign.

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