Xanthogranulomatous pyelonephritis in early infancy.

Xanthogranulomatous pyelonephritis is a severe, atypical form of chronic renal parenchymal infection, which mimics neoplasia and other inflammatory renal parenchymal diseases. Although xanthogranulomatous pyelonephritis has characteristic findings on sonography and CT scan, a clinical diagnosis is seldom possible. Correct diagnosis is made on exploration, by the presence of dense adhesions to the surrounding tissue and presence of pus in the kidney, which is confirmed histopathologically by the presence of lipid laden foamy macrophages, accompanied by both chronic and acute phase inflammatory cells.