Clinicopathological features of xanthogranulomatous pyelonephritis in infancy.

Xanthogranulomatous pyelonephritis (XGP) is an unusual chronic inflammatory condition which most often affects women in their 5th to 7th decades and is rare in infants. Predisposing factors include infection, calculi and obstructive uropathy. We have reviewed the surgical files of 4 cases seen over a 28 yr period from 1964-91. All of the 3 partial and one total nephrectomy specimens demonstrated typical features of XGP with renal parenchyma effaced by a mixed acute and chronic inflammatory infiltrate which included prominent aggregates of foamy histiocytes containing eosinophilic inclusions. No Michaelis-Gutmann bodies were seen. This study shows the association of XGP with chronic infection, anatomical malformation and reflux in infancy, and raises the possibility of a temporary altered immune response in its pathogenesis.