ATLAS OF PATHOLOGY

Acute pyelonephritis is an exudative purulent localized inflammation of kidney and renal pelvis. The renal parenchyma presents in the interstitium abscesses (suppurative necrosis), consisting in purulent exudate (pus): neutrophils, fibrin, cell debris and central germ colonies (hematoxylinophils). Tubules are damaged by exudate and may contain neutrophil casts. In the early stages, glomeruli and vessels are normal. (Hematoxylin-eosine, ob. x10)