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| Xanthogranolomatous Pyelonephritis |
| Etiology |
•The disease process is essentially infectious. •Proteus is a frequent associated causative organism. •Chronic obstruction plays a part in the development of the disorder. |
| Pathogenesis |
| Most cases are due to ascending infections from urine flow
abnormalities. •Urinary outflow obstruction results in urine stasis providing an environment for bacterial proliferation.
•Obstruction also predisposes to vesicoureteral reflux which can enable bacteria to reach the kidney. •The resulting inflammation may be massive and mimic adenocarcinoma. |
| Epidemiology |
•Xanthogranulomatous pyelonephritis is a form of chronic pyelonephritis and is related to disease states that are obstructive and lend themselves to ascending infections. |
| Clinical |
•Peak incidence in 4th to 6th decades of life. •The clinical features are essentially that of chronic pyelonephritis. •Some cases are associated with nephrolithiasis. |
| General Gross Description |
•Xanthogranulomatous pyelonephritis is usually unilateral and may involve all or portion of a kidney. •The affected renal parenchymal is brightly yellow and may take on a nodular quality mimicking renal cell carcinoma. •Not uncommonly there is associated evidence of urine outflow obstruction such as stone disease and hydronephrosis. |
| General Micro Description |
•The characteristic histologic feature of xanthogranulomatous pyelonephritis is the abundance of lipid-laden macrophages as part of the inflammatory process resulting in the gross yellow appearance. •Other components of the inflammation include lymphocytes, plasma cells neutrophils and scattered multinucleated giant cells. |
| Reference |
• Cotran RS, Kumar V, Robbins SL: Robbins Pathologic Basis of Disease. 5th ed. Philadelphia, W.B. Saunders, 1994, pp. 971-972. •Murphy WM. Urological Pathology. Philadelphia: W.B.Saunders, 1989, pp. 419-421.
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