Description, Causes and Risk Factors:
Def: A chronic inflammatory condition diffusely involving the entire kidney and usually resulting in a grossly enlarged and functionless kidney that can grossly resemble a neoplasm or tuberculosis; histologically, it is characterized by an inflammatory reaction with numerous lipid-laden, foamy histiocytes mixed with lymphocytes and plasma cells to form multiple granulomas.
Xanthogranulomatous pyelonephritis is an uncommon form of severe chronic renal infection. It usually occurs on one side and may be diffuse (multifocal) or segmental (tumefactive). The overall incidence is probably < 0.5% of all chronic renal infections. It is usually seen in older age groups, and is more common in females.
The disease is almost always unilateral and appears to represent an abnormal immune response to infection with giant cells, lipid-laden macrophages, and cholesterol clefts, which accounts for the yellow color of the infected tissue. Two presentations occur in children. The most common affects boys and girls equally and involves the entire kidney. The other form, which is more common in girls, is localized and may mimic a tumor. XPN displays neoplasm-like properties capable of local tissue invasion and destruction, and has been referred to as a pseudotumor.
The etiology is unknown. Possible predisposing factors are urinary tract infection (UTI), abnormal lipid metabolism, immunologic compromise with urinary tract infection, and diabetes. It is usually associated with chronic UTI by Proteus mirabilis, E. coli (Escherichia coli), Klebsiella, Enterobacter, Serratia, and Providencia.
It has been described in three stages:
Kidney and perinephric fat.
Kidney, perinephric fat and retroperitoneal extension.
The typical presenting features include:
Fever, malaise, anorexia.
A palpable flank mass may be present, which may be tender ordemonstrate renal angle tenderness.
XPN has been termed the great imitator, because it may bemisdiagnosed as a renal neoplasm, especially if the lesion isfocal.
It is difficult to make a preoperative differential diagnosis of XPN from other forms of chronic inflammatory conditions. Early diagnosis helps prevent inevitable loss of kidney. Clinical features, imaging, urine cytology, and kidney biopsy are helpful in making diagnosis.
Although the diagnosis of XPN is mainly achievedhistologically,a suggestive preoperative diagnosis anddetermination of the extent of the lesion byultrasonography, CT, MR imaging, or any combinationcould allow less radical surgery in selected focal XPN cases. However in absence of signs of inflammation/infection/obstruction diagnosis may be completely basedon histological evaluation of nephrectomy specimen.
XPN is associated with virtually complete destruction of the kidney. Treatment is therefore surgical (after an initial course of antimicrobials to control the local infection) and consists of en-bloc nephrectomy, in which all the involved tissue is removed and any fistulas closed. Patients with a localized form (usually children) or with bilateral disease can be treated with partial nephrectomy. Kidney may be preserved in stages I and II.
Medical therapy has proven sufficient for treatment of xanthogranulomatous pyelonephritis in only a handful of cases. Antibiotics may be appropriate as a temporizing measure in patients who require a medical workup prior to nephrectomy. Similarly, appropriate antibiotics should be administered prior to operative intervention. The choice of antibiotic should be geared toward the identity and sensitivity of the organism.
NOTE: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.
DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.
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