Xanthogranulomatous pyelonephritis • Def: Condition associated with chronic obstruction (e.g., staghorn calculi) and urinary tract infections with resulting destructive granulomatous inflammation • CT: low-density masses with calcifications mimicking renal malignancy • Histology: granulomatous inflammation with diffuse cellular infiltrate of lipid-laden foam cells (lipid-laden macrophages)→ replacing normal renal parenchyma • Clinical manifestations: commonly affect middle-aged women who may present with fevers/chills, chronic flank pain, and, possibly, palpable mass. • Urine cultures: may reveal gram-negative organisms such as E. coli, Klebsiella, or Proteus and, less commonly, Staphylococcal species. • Management: organism-specific antibiotics, relief of obstruction, but total or partial nephrectomy as needed

2. • Def: Condition associated with chronic obstruction (e.g., staghorn calculi)
and urinary tract infections  destructive granulomatous inflammation
• Histology: granulomatous inflammation with diffuse cellular infiltrate of
lipid-laden foam cells (lipid-laden macrophages)→ replacing normal renal
parenchyma
• Clinical manifestations: commonly affect middle-aged women who may
present with fevers/chills, chronic flank pain, and, possibly, palpable mass.

3. • Urine cultures: may be gram-negative organisms such as E. coli,
Klebsiella, or Proteus and, less commonly, Staphylococcal species.
• CT  Enlarged nonfunctioning kidney, with presence of calculi and
low-density masses (xanthomatous tissue) difficult to distinguish
from renal malignancy
• Management: organism-specific antibiotics, relief of obstruction, but
total or partial nephrectomy