Extensive retroperitoneal mass

Pseudoneoplastic Xanthogranulomatous Pyelonephritis

“…The inflammatory process may have spread throughout the peri renal fat and the entire retroperitoneum. Renocolic and renocutaneous fistula have been reported [2,7], Microscopic pathological examination of the yellow areas reveals the characteristic features of xanthogranulomatous pyelonephritis: a large number of 'lipid-laden macrophages' (xanthogranulomatous cells) with extensive areas of inflammation and fibrosis.…”