Pyelonephritis Xanthogranulomatous pyelonephritis 2021-04-30T11:02:02Z Xanthogranulomatous pyelonephritis is an uncommon chronic destructive granulomatous process of renal parenchyma in association with long-term urinary tract obstruction and infection. Xanthogranulomatous pyelonephritis is a granulomatous inflammatory infiltrate composed of neutrophils, lymphocytes, plasma cells, xanthomatous histiocytes, and multinucleated giant cells.