<h1><br></h1><h2>Definition of Xanthogranulomatous Pyelonephritis</h2><p>Xanthogranulomatous pyelonephritis (XP) is a rare form of <a href="http://www.urology-textbook.com/chronic-pyelonephritis.html"><u><font color="#0066cc">chronic pyelonephritis</font></u></a> with foam cells (large macrophages with foamy lipid-containing cytoplasm), which lead to kidney destruction.</p><h3>Epidemiology</h3><p>XP is rare (<a href="http://www.urology-textbook.com/incidence.html"><u><font color="#0066cc">incidence</font></u></a> 1.4/100000), women are more likely affected than men.</p><h2>Etiology </h2><p>XP is usually a unilateral renal disease, which develops in nonfunctioning kidneys with nephrolithiasis, <a href="http://www.urology-textbook.com/urinary-tract-infection.html"><u><font color="#0066cc">urinary tract infection</font></u></a> and <a href="http://www.urology-textbook.com/hydronephrosis.html"><u><font color="#0066cc">upper urinary tract obstruction</font></u></a>. The most commonly isolated bacterial organisms are <i>E. coli</i>, <i>Proteus</i>, <i>Klebsiella</i> and <i>Staphylococcus</i>. </p><h2>Pathology of of Xanthogranulomatous Pyelonephritis</h2><h4>Macroscopic Pathology:</h4><p>Enlarged kidney, enlarged renal pelvis filled with pus (pyonephrosis), orange-yellow inflammatory lesions in addition to tissue necrosis and small abscesses. The renal involvement is limited initially to segments of the kidney, later the inflammatory process involves most of the kidney. Hereby, the renal parenchyma is replaced by a granulomatous inflammatory tissue and loses its function. The disease may spread into adjacent structures of the retroperitoneum. </p><h4>Histology:</h4><p>The inflammatory tissue contains neutrophils, lymphocytes, plasma cells, necrosis, and large macrophages with foamy lipid-containing cytoplasm. Sometimes epitheloid granulomas are found. </p><h2>Signs and Symptoms of Xanthogranulomatous Pyelonephritis</h2><ul title="signs and symptoms of xanthogranulomatous pyelonephritis"><li>Flank pain (70%) </li><li>Fever and chills (70%) </li><li>Flank tumor </li><li>Persistent bacteriuria </li><li>General malaise and weight loss. </li></ul><h2>Diagnostic Work-up</h2><h4>Urine sediment:</h4><p><a href="http://www.urology-textbook.com/urine-analysis.html"><u><font color="#0066cc">Urine sediment</font></u></a> shows leukocyturia, bacteriuria, and possibly the detection of foam cells (lipid-laden macrophages). </p><h4>Urine culture:</h4><p><a href="http://www.urology-textbook.com/urine-culture.html"><u><font color="#0066cc">Urine culture</font></u></a> has a low specifity, but often positive. </p><h4>Renal ultrasound:</h4><p><a href="http://www.urology-textbook.com/renal-ultrasound.html"><u><font color="#0066cc">Renal ultrasound</font></u></a> shows an enlarged kidney with a mixed echogenic mass, it can not be reliably distinguished from a malignant tumor. Nephrolithiasis may be seen. </p><h4>Intravenous urography: </h4><p>KUB x-ray may show an increased renal shadow and nephrolithiasis. Urogram reveals in 30-80% a missing renal function with no opacification of the affected side. </p><h4>Computed tomography: </h4><p>CT is the diagnostic tool of choice. It shows a lesion of the kidney with inhomogeneous contrast enhancement, reduced kidney function, hydronephrosis and detection of nephrolithiasis. Often, <a href="http://www.urology-textbook.com/renal-cell-carcinoma.html"><u><font color="#0066cc">renal cell carcinoma</font></u></a> cannot be ruled out. <br></p>
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