Case In Point
Acute Renal Failure Caused by Xanthogranulomatous Pyelonephritis
Sydney Asselstine, MD • Kevin Ly, MD • Nicole Castro, MD • Anand Shah, MD • Robert Kim, MD • Jacey Pudney, MD • Sairah Johnson, MD • Deshanki Pandya, MD • Krishna Parikh, MD • Zeeshan Khan, MD •Maria Ciminelli, MD
Resident, Family Medicine Department, Rutgers Robert Wood Johnson Medical School, Freehold, New Jersey
Asselstine S, Ly K, Castro N, et al. Acute renal failure caused by xanthogranulomatus pyelonphritis. Consultant. Published online October 12, 2021. doi:10.25270/con.2021.10.00002
Received April 28, 2021. Accepted May 14, 2021.
The authors report no relevant financial relationships.
Sydney Asselstine, MD, Rutgers Robert Wood Johnson Medical School, 597 Park Avenue, Suite A, Freehold, NJ 07728 (email@example.com)
An unresponsive 47-year-old woman with uncontrolled type 2 diabetes was brought to the emergency department because of a hypoglycemic episode. After her mental status had improved following administration of intravenous dextrose, it was discovered that she had a progressive history of unintentional weight loss, flank pain, edema, and dyspnea upon exertion over the past several months.
She denied fevers or hematuria. She was taking oral cephalexin for urinary frequency and dysuria, prescribed in the outpatient setting, but a review of outpatient records revealed no growth of organisms in the urine culture.
Physical examination. The patient was afebrile with stable vital signs. She had dry oral mucosa and bilateral conjunctival pallor. Her respiratory examination was significant for crackles in the right lung up to the middle lobe. A cardiac examination revealed a notable III/VI systolic murmur, loudest at the right upper sternal border. Her abdominal examination findings were unremarkable, without tenderness or distension, and she had no costovertebral angle tenderness. Her lower extremities had 3+ pitting edema to the upper shins bilaterally with negative Homans sign. She had no gross neurological deficits.
Diagnostic testing. Initial laboratory study findings were significant for a low hemoglobin level of 7.6 g/dL, with iron studies revealing a low percent saturation of 5%, a low iron level of 12 μg/dL, and an elevated total iron-binding capacity of 228 μg/dL, indicating mixed anemia. No leukocytosis was noted.
Other abnormalities included hyponatremia with a sodium level of 131 mEq/L, an elevated creatinine level of 1.1 mg/dL with unknown baseline, a low glomerular filtration rate of 53 mL/min, and a low albumin level of 2.3 g/dL. Results of a urinalysis revealed cloudy urine with 3+ proteinuria, 1+ glucosuria, 1+ hematuria, trace leukocyte esterase, and trace bacteria. A 24-hour urine collection yielded more than 7 g of protein. Urine cultures did not grow bacteria.
An initial chest radiograph showed a moderate right pleural effusion with no infiltrates (Figure 1). An abdominal ultrasound showed severe dilation of the right renal collection system with cortical thinning measuring 17.7 cm × 11.0 cm × 12.1 cm and an unremarkable left kidney. A follow-up computed tomography scan of the abdomen confirmed a severely dilated right kidney with a focal hypodense region in the inferior cortex, measuring 5.8 cm × 2.1 cm (Figure 2). The patient was admitted to the hospital for further workup of this abnormal renal finding and management of her fluid overload.
Figure 1. An initial chest radiograph showed a moderate right pleural effusion with no infiltrates.
Figure 2. A computed tomography scan of the abdomen confirmed a severely dilated right kidney (A) with a focal hypodense region in the inferior cortex (B).
The initial differential diagnoses for this patient included diabetic nephropathy, membranous glomerulonephritis, focal segmental glomerulosclerosis, and minimal change disease, given the patient’s extensive proteinuria. The additional feature of a significantly enlarged right kidney required broadening of the differential diagnosis. Other etiologies were considered, including renal cell carcinoma, leiomyosarcoma, pyelonephritis, and nephrolithiasis.
Treatment. The patient underwent a right thoracentesis for her pleural effusion, which provided some symptom improvement. Pleural fluid was noted to be transudative based on Light’s Criteria of a pleural-to-serum protein ratio of less than 0.5 and a pleural-to-serum lactate dehydrogenase ratio of less than 0.6. (Table).
A nephrologist evaluated the patient and recommended intravenous diuresis with albumin repletion. Despite this treatment, she had persistent edema and recurrence of the pleural effusion requiring a second thoracentesis, which showed exudative fluid. A video-assisted thoracoscopic surgery procedure with decortication and partial pleurectomy was performed, and a chest tube was placed. The nephrologist also recommended a biopsy of the left kidney, as the right kidney did not have enough functioning tissue. Results of which revealed diabetic nephropathy and focal segmental glomerulosclerosis.
Given that she had little improvement in clinical status and that her glomerular filtration rate had decreased by 62%, the patient was started on hemodialysis for fluid removal, meeting the criteria for stage 3 renal injury based on the Acute Kidney Injury Network staging. With dialysis, the patient symptomatically improved, at which point a urologist evaluated her and recommended proceeding with a right radical nephrectomy. An atrophic, 396-g kidney and the adrenal gland were removed. A pathologist identified that the renal pelvis, calyces, and medulla were replaced by a fungating golden yellow-tan, mass-like lesion in an infiltrative pattern diffusely.
The pathological diagnosis of xanthogranulomatous pyelonephritis (XGP) caused by Klebsiella was made. The patient was evaluated by infectious disease specialists and received a 7-day course of intravenous ceftriaxone prior to discharge. Upon discharge, the patient did not receive suppressive antibiotics because the bacterial source had been effectively removed via the nephrectomy and she showed no further signs of infection. She had an arteriovenous fistula placed as an outpatient, remains on dialysis, and is clinically stable.
Discussion. XGP is an uncommon condition associated with chronic urinary tract infections, which leads to damage of the renal parenchyma.1 The most frequently associated organisms are Escherichia coli and Proteus mirabilis.1-3 XGP accounts for 0.6% of all histologically documented chronic pyelonephritis.3
First hypothesized in 1916, XGP was described in 3 distinct forms: diffuse, segmental, and focal.3 The incidence rate is increased among patients with diabetes, pregnancy, rheumatoid arthritis, or cirrhosis. It is also more common among women, with a mean age of occurrence from 45 to 55 years.3,4 Patients often present with urinary symptoms, edema, hypertension, a palpable flank mass, hematuria, and weight loss. Laboratory workup may identify an increased erythrocyte sedimentation rate, alkaline phosphatase level, white blood cell count, and aspartate aminotransferase level, in addition to a low albumin level. Computed tomography scanning is commonly used as an initial imaging modality and may show associated hydronephrosis, renal calculi, cortical atrophy, or intraparenchymatous collections, but the differential diagnosis must remain broad until histopathological diagnosis can be made.4,5
Complications related to XGP include chronic bacteriuria, fistula formation, renal cell carcinoma and emphysematous pyelonephritis. Nephrectomy is the treatment of choice and often leads to positive outcomes and resumption of normal renal function and resolution of symptoms.6,7 Chronic antibiotic therapy has had some success in patients who are not candidates for surgery.8
1. Kundu R, Baliyan A, Dhingra H, Bhalla V, Punia RS. Clinicopathological spectrum of xanthogranulomatous pyelonephritis. Indian J Nephrol. 2019;29(2):111-115. https://doi.org/10.4103/ijn.ijn_50_18
2. Hartman DS, Davis CJ Jr, Goldman SM, Isbister SS, Sanders RC. Xanthogranulomatous pyelonephritis: sonographic--pathologic correlation of 16 cases. J Ultrasound Med. 1984;3(11):481-488. https://doi.org/10.7863/jum.1918.104.22.1681
3. Li L, Parwani AV. Xanthogranulomatous pyelonephritis. Arch Pathol Lab Med. 2011;135(5):671-674. https://doi.org/10.5858/2009-0769-rsr.1
4. Craig WD, Wagner BJ, Travis MD. Pyelonephritis: radiologic-pathologic review. Radiographics. 2008;28(1):255-328. https://doi.org/10.1148/rg.281075171
5. Begum T, Huq ME, Ahmed M. Xanthogranulomatous pyelonephritis. BMJ Case Rep. Published online June 15, 2016. https://doi.org/10.1136/bcr-2016-216025
6. Craig WD, Wagner BJ, Travis MD. Pyelonephritis: radiologic-pathologic review. Radiographics. 2008;28(1):255-328. https://doi.org/10.1148/rg.281075171
7. Al-Ghazo MA, Ghalayini IF, Matalka II, Al-Kaisi NS, Khader YS. Xanthogranulomatous pyelonephritis: Analysis of 18 cases. Asian J Surg. 2006;29(4):257-261. https://doi.org/10.1016/s1015-9584(09)60099-3
8. Ho CI, Wen YK, Chen ML. Xanthogranulomatous pyelonephritis successfully treated with antibiotics only. J Chin Med Assoc. 2008;71(12):643-645. https://doi.org/10.1016/s1726-4901(09)70008-5