- Middle-aged to elderly patients (female), diabetes has been described as a risk factor
- Related to staghorn calculi
- A chronic granulomatous process inciting a chronic but incomplete immune reaction –> granulation tissues & lipid laden macophages replace normal renal tissues around the stone
- Generalized inflammation in the affected kidney often spreads into adjacent structures, including fistulaization and psoas abscess formation.
- Presence of staghorn calculi
- An enlarged hypoattenuating kidney (inflammation) with a contracted pelvis, dilated calyces seen as bear paw sign
- Surgical nephrectomy is usually curative. The degree of inflammatory involvement of adjacent structures may favor an open approach in many cases.