The patient went on to have a left nephrectomy.
Histology
MACROSCOPIC DESCRIPTION:
A left nephrectomy specimen weighing 862 g and measuring 135 x 82 x 80 mm. The external surface is pale tan and multinodular. On cut section, numerous yellow-brown calculi, measuring up to 25 mm in maximum dimension, are identified within the dilated pelvicalyceal system. Other calyces contain green-yellow fibrinous material and pus. The overlying cortex is thinned and there is loss of cortico-medullary differentiation. At the posterior surface, there is an extrarenal collection of pus measuring up to 48 mm in maximum dimension. Hilar vascular and ureteric resection margins are obscured by fibrinous material but appear otherwise unremarkable. No perinephric lymph nodes are identified.
MICROSCOPIC DESCRIPTION:
Sections of the kidney show active chronic xanthogranulomatous inflammation. There are scattered areas of necrosis, being surrounded by palisaded histiocytes. Multinucleated giant cells are occasionally seen. There are many neutrophils, lymphocytes, plasma cells and foamy macrophages. The inflammation extends into the surrounding perinephric fat. Some of the glomeruli are sclerosed. There is dilatation and thyroidisation of the tubules, containing eosinophilic secretion and inflammatory cells. The interstitium is markedly inflamed, along with fibrosis. Some of the blood vessels show moderate to severe thickening. No tumour is identified. The vascular resection margins are unremarkable. The Gram stain shows no bacteria. The Grocott stain shows no fungi. The Ziehl-Neelsen stain shows no acid fast bacilli.
FINAL DIAGNOSIS:
Left kidney: nephrolithiasis with secondary active xanthogranulomatous pyelonephritis and hydronephrosis.