CPC #3 Pathology

Radical Nephrectomy

• Three intrarenal masses with cystic change (9, 7, and 5cm)

• Nodular Mass (3cm) in perirenal fat

Not all Renal Tumors (Masses) are Renal Cell Carcinoma!

• Angiomyolipoma

• Oncocytoma

• Xanthogranulomatous Pyelonephritis

• Malakoplakia

• Adrenal Rest

Xanthogranulomatous Pyelonephritis

• Subacute/chronic inflammation forming a mass lesion in the kidney

• Tender unilateral flank mass

• Nephrolithiasis (70%)– Long term recurrent obstruction

• Adults

• Female Predominance (2:1)

Xanthogranulomatous Pyelonephritis

• Gross:– yellow mass often extending into perirenal fat,

mimicking renal cell carcinoma• Microscopic:

– Lipid-laden macrophages– Fibroblastic proliferation– Lymphocytes, plasma cells– Microabscesses

• Microbiology:– Often Proteus mirabilis, E. Coli

CD68

Diagnosis

Xanthogranulomatous Pyelonephritis

ACID-FAST STAIN

ACID-FAST STAIN

Diagnosis

• Xanthogranulomatous Pyelonephritis

• Numerous Acid-fast Bacilli

Similar Cases in Literature

• Shah HN et al. Renal tuberculosis simulating xanthogranulomatous pyelonephritis with contagious hepatic involvement. Int J Urology 2006;13: 67-68.

• Izbudak-Oznur et al. Renal tuberculosis mimicking xanthogranulomatous pyelonephritis: ultrasonography, computed tomography and magnetic resonance imaging findings. Turk J Pediatr 2002;44: 168-171

Important Point

• Immunocompromised patients often do not form granulomas well

• One may see Mycobacterial or Fungal Infections without well-formed granulomas