Xanthogranulomatous perinephritis: unusual cause of renal vein and vena caval thrombosis.

Xanthogranulomatous pyelonephritis is an uncommon form of chronic renal infection which can be confused clinically, radiographically, and pathologically with renal carcinoma. Occasionally, xanthogranulomatous changes are more prominent in perinephric tissue than in the renal parenchyma itself. We present a case of locally invasive xanthogranulomatous perinephritis associated with thrombosis of the renal vein and inferior vena cava. With this constellation of findings, infections as well as malignant etiologies should be considered in the differential diagnosis.