Xanthogranulomatous pyelonephritis

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Xanthogranulomatous pyelonephritis
Diagnosis in short

Xanthogranulomatous pyelonephritis. CD68 immunostain.

LM abundant (foamy) macrophages (associated with the collecting system - medulla, not cortex), +/-giant cells, +/-cholesterol clefts, +/-interstitial lymphocytes and plasma cells, +/-interstitial fibrosis, +/-calcifications
LM DDx malakoplakia, RCC - especially PRCC, granulomatous disease, chronic pyelonephritis, interstitial nephritis, occasionally renal cell carcinoma
Stains PAS-D -ve
IHC CD68 +ve, CD10 -ve, pankeratin -ve
Site kidney - see kidney tumours

Associated Dx diabetes mellitus, history of UTI, nephrolithiasis, GU obstruction (various causes)
Prevalence uncommon
Radiology dilated upper GU system
Clin. DDx renal cell carcinoma, pyelonephritis
Treatment antibiotics, occasionally nephrectomy

Xanthogranulomatous pyelonephritis, abbreviated XGP, is an inflammatory process of the kidney that can mimic renal cell carcinoma.

General

Microscopic

Features:

  • Abundant (foamy) macrophages.
    • Associated with the collecting system - medulla, not cortex.
  • +/-Giant cells.
  • +/-Interstitial lymphocytes and plasma cells.
  • +/-Interstitial fibrosis.
  • +/-Cholesterol clefts (common).
  • +/-Calcifications - dystrophic.

DDx:

Images

www:

Stains

  • PAS-D -ve.
    • Done to look for malakoplakia.

IHC

  • CD68 +ve.
  • RCC markers (CD10, RCC) all negative.

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RIGHT KIDNEY, NEPHRECTOMY:
- XANTHOGRANULOMATOUS PYELONEPHRITIS.
- CHRONIC INTERSTITIAL NEPHRITIS.
- INCREASED NUMBERS OF TOTALLY SCLEROSED GLOMERULI AND GLOMERULI WITH FOCAL 
  SCLEROSIS.
- MARKED INTERSTITIAL FIBROSIS.
- NEGATIVE FOR MALIGNANCY.

COMMENT:
Immunostaining demonstrates abundant CD68 positive cells (macrophages).  A CD10 immunostain 
is non-concerning (it highlights glomeruli). A pankeratin immunostain is non-concerning 
(it highlights benign renal tubules).

Compatible XGP

"KIDNEY" LESION, LEFT, BIOPSY:
- FIBROMUSCULAR TISSUE WITH A MIXED INFLAMMATORY INFILTRATE.
- CELLULAR DEBRIS WITH SURROUNDING LOOSELY AGGREGATED HISTIOCYTES.
- NO RENAL PARENCHYMA IDENTIFIED.
- NEGATIVE FOR MALIGNANCY.

COMMENT:
A SMA immunostain highlights the muscle component, and a CD68 immunostain marks 
abundant histiocytes. No epithelial component is identified with a pankeratin 
immunostain. 

Micro

The sections show degenerative renal parenchyma with surrounding histiocytes, other inflammatory cells, fibrosis and cholesterol clefts.

See also

References

  1. 1.0 1.1 Afgan F, Mumtaz S, Ather MH (2007). "Preoperative diagnosis of xanthogranulomatous pyelonephritis". Urol J 4 (3): 169–73. PMID 17987581.
  2. 2.0 2.1 2.2 Al-Ghazo MA, Ghalayini IF, Matalka II, Al-Kaisi NS, Khader YS (October 2006). "Xanthogranulomatous pyelonephritis: Analysis of 18 cases". Asian J Surg 29 (4): 257–61. PMID 17098659.
  3. Iskandar, SS.; Prahlow, JA.; White, WL. (Jun 1993). "Lipid-laden foamy macrophages in renal cell carcinoma. Potential frozen section diagnostic pitfall.". Pathol Res Pract 189 (5): 549-52. doi:10.1016/S0344-0338(11)80364-X. PMID 8378177.
  4. Li, L.; Parwani, AV. (May 2011). "Xanthogranulomatous pyelonephritis.". Arch Pathol Lab Med 135 (5): 671-4. doi:10.1043/2009-0769-RSR.1. PMID 21526966.