Xanthogranulomatous pyelonephritis

 

Xanthogranulomatous pyelonephritis is an uncommon, severe, subacute, or chronic suppurative process characterized by destruction and replacement of the renal parenchyma by granulomatous tissue containing histocytes and foamy cells. It is most often associated with chronic obstruction and stones with ongoing infection. It is also referred to as a pseudotumor due to an enlarged kidney resembling a tumor and the ability of local invasion and destruction.

The etiology remains unknown. However, most of the cases result from chronic urinary obstruction and infection. The organisms most commonly associated with XGP are Escherichia coli, Proteus mirabilis, Pseudomonas, Enterococcus faecalis, and Klebsiella, etc. Urinary obstruction occurs as a result of calculus, most commonly, staghorn calculus (in almost 80% of patients), which serves as a nidus for infection resulting in the destruction of the renal parenchyma.