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Case report

Radiological finding of pneumomediastinum as a rare complication of emphysematous pyelonephritis

Ksenija Mijović1, Nevena Stanišić1, Dragan Mašulović1,2, Dušan Šaponjski1, Nikola Bogosavljević3, Dragan Vasin1, Milica Mitrović Jovanović1
  • University Clinical Center of Serbia, Center for Radiology and Magnetic Resonance Imaging, Belgrade, Serbia
  • University of Belgrade, Faculty of Medicine, Serbia
  • Institute for Orthopedic Surgery “Banjica”, Belgrade, Serbia

ABSTRACT

Introduction: Emphysematous pyelonephritis is a rare, acute, and life-threatening necrotizing renal infection caused by gas-producing facultative anaerobes, such as Escherichia coli, Klebsiella, and Proteus, most commonly in the setting of underlying diabetes mellitus. Pneumomediastinum is a rare imaging finding in this disease, and a high index of suspicion is required for diagnosing emphysematous pyelonephritis in patients presenting with pneumomediastinum, in the right clinical setting.

Case presentation: We present the case of a middle-aged female patient with symptoms and laboratory findings indicating infection, renal failure, and hyperglycemia, and a personal history of diabetes mellitus. The imaging procedures revealed findings of a severe and advanced necrotizing renal infection with parenchymal destruction and intraparenchymal gas collections extending into the perirenal and pararenal spaces. We established the diagnosis of emphysematous pyelonephritis accompanied by perirenal abscess formation and pneumoretroperitoneum, with gas collections propagating into the mediastinum. In the setting of such a severe form of infection, the patient underwent immediate surgery with left nephrectomy. Despite prompt and intensive treatment, the patient unfortunately succumbed to the disease during the postoperative period.

Conclusion: Pneumomediastinum is a rare complication of retroperitoneal processes, and, when present, indicates their extensiveness, often being an ominous prognostic sign. By presenting this case, we aim to highlight the severity of this form of renal infection and the unequivocal need for immediate response, as well as to emphasize the significance of imaging findings, which are somewhat unusual, but should raise suspicion of an insidious and serious retroperitoneal infection.


INTRODUCTION

Emphysematous pyelonephritis (EPN) is a rare, acute, and life-threatening necrotizing renal disease defined as necrotizing infection with gas particles within the renal parenchyma, the kidney collecting system, or in the perirenal space [1]. It mainly occurs in patients with uncontrolled diabetes mellitus and is more frequent in women. It is most commonly caused by gram-negative facultative anaerobes, such as E. coli, Klebsiella, and Proteus [2].

The disease may be asymptomatic, or it may present with nonspecific symptoms, such as generalized fatigue, fever, lower back pain, or it may imitate intestinal obstruction and GI tract perforation and, combined with nonspecific laboratory test results, the result is that diagnosis is often established late [3],[4],[5]. Computerized tomography (CT) is the most reliable method for establishing a timely diagnosis, evaluating the distribution of gas inclusions and fluid, as well as for monitoring the course of the disease [6].

CASE PRESENTATION

A 56-year-old female patient presented at the Emergency Clinic of the University Clinical Center of Serbia with symptoms of extreme fatigue, accompanied by fever, dyspnea, and obstipation. These symptoms had been present the previous 7 days. Laboratory findings showed leukocytosis (26 x 109 /l) with neutrophilia (88.6%), a high level of C-reactive protein (280.6 mg/l), a very high level of procalcitonin (49.2 ng/ml), elevated levels of nitrogenous substances: urea – 29.7 mmol/l and creatinine – 286 μmol/l, as well as extreme hyperglycemia, even after insulin administration. In her anamnesis, the patient stated diabetes as a chronic disease.

Native radiography of the abdomen showed signs of extraluminal gas, in the form of pneumoperitoneum, while abdominal ultrasonography showed a large amount of gas in the left retroperitoneal space, which limited the visibility of the left kidney. The computerized tomography (CT) finding showed an enlarged left kidney, with a disintegrated parenchyma, within which small circular and linear gas inclusions were visible that extended into the perirenal space, in whose posteromedial aspect an abscess formation with an air-fluid level was also visible (Figure 1). The complete finding indicated the existence of EPN. Gas inclusions were also visible in the left retroperitoneal space, as well as in the psoas muscle, with extensions into the musculature of the left coxofemoral joint. Inclusions of free gas were also visible contralaterally in the anterior pararenal space, precavally, with retrocrural extension into the mediastinum (Figure 2). Further superior extension of gas inclusions reached the level of the superior thoracic aperture presenting the radiological finding of pneumomediastinum (Figures 3 and 4).

11 01

Figure 1. Axial CT section at the left kidney upper pole level demonstrating an abscess formation in the posteromedial aspect, with an air-fluid level.

11 02

Figure 2. Axial plane showing destroyed left renal parenchyma with intraparenchymal gas and gas inclusions extending to the perirenal and pararenal spaces. Gas is also visible in the contralateral posterior pararenal space, as well as in the anterior abdominal wall.

11 03

Figure 3. Coronal reformation showing gas in the pericaval space extending superiorly into the basal portions of the mediastinum. The gas inclusions are seen in the tissues outlining the aortic arch.

11 04

Figure 4. Axial plane through the mediastinum at the subcarinal level shows gas outlining the great mediastinal vessels, as well as gas inclusions in the anterior mediastinum.

The intraoperative finding in our patient revealed complete parenchymal destruction in the left kidney, which is why total left nephrectomy was performed. The pathohistological finding showed chronic pyelonephritis and perinephritis with acute purulent exacerbation and abscess formation, with hemorrhagic parenchymal infarctions. Unfortunately, the patient postoperatively succumbed to the illness.

DISCUSSION

We present a case of EPN with pneumoretroperitoneum and pneumomediastinum, which is a rare complication. The retroperitoneum, mediastinum, and subcutaneous tissue are connected and in communication with one another, linked together by fascial tissue spaces along which large blood vessels and diaphragm fibers extend, which enables free gas developing in any of these areas to easily extend into any of the other regions. Thus, retroperitoneal gas, developing as the result of an infection caused by gas-producing bacteria, may reach the mediastinum and the subcutaneous tissue and result in the development of pneumomediastinum and subcutaneous emphysema [7],[8], which was, indeed, the case with our patient (Figure 5).

11 05

Figure 5. Sagittal reformation image depicting gas inclusions, both in the left retroperitoneum and the anterior mediastinum.

Based on gas inclusion distribution and the degree of involvement of the kidney, EPN has been classified into three classes:

Class 1: gas in the kidney collecting system

Class 2: gas in the kidney parenchyma

Class 3a: gas propagation into the perirenal space

Class 3b: gas propagation into the pararenal space

Class 4: bilateral EPN or the only kidney with EPN [9].

Based on this classification, our patient was categorized as Class 3b.

Mortality is high and may be as high as 80% in the absence of a surgical procedure [2]. When the parenchyma of the kidney is preserved, initial treatment is conservative, with possible percutaneous drainage or ureteral stenting. In case of diffuse and advanced infection with extensive parenchyma destruction, the indication for urgent surgery becomes quite clear [8].

EPN is a life-threatening infection caused by gas-producing microorganisms, which most commonly requires nephrectomy, and which may be complicated by propagation of gas inclusions along extraperitoneal tissues, rarely reaching the mediastinum. Therefore, the finding of pneumomediastinum of unknown cause with a certain clinical presentation warrants the inclusion of EPN into the differential diagnosis. As far as we could find, by researching available literature, pneumomediastinum is a rare complication of EPN and it correlates with an advanced stage of disease.

  • Conflict of interest:
    None declared.

Informations

Volume 3 No 1

Volume 3 No 1

March 2022

Pages 108-112
  • Received:
    02 January 2022
  • Revised:
    14 February 2022
  • Accepted:
    17 February 2022
  • Online first:
    18 March 2022
  • DOI:
Corresponding author

Ksenija Mijović
Center for Radiology and Magnetic Resonance Imaging, University Clinical Center of Serbia
2 Pasterova Street, 11000 Belgrade, Serbia
E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.



References

1. Misgar RA, Mubarik I, Wani AI, Bashir MI, Ramzan M, Laway BA. Emphysematous pyelonephritis: A 10-year experience with 26 cases. Indian J Endocrinol Metab. 2016 Jul-Aug;20(4):475-80. doi: 10.4103/2230-8210.183475.[CROSSREF]

2. Lu YC, Hong JH, Chiang BJ, Pong YH, Hsueh PR, Huang CY, et al. Recommended Initial Antimicrobial Therapy for Emphysematous Pyelonephritis: 51 Cases and 14-Year-Experience of a Tertiary Referral Center. Medicine (Baltimore). 2016 May;95(21):e3573. doi: 10.1097/MD.0000000000003573.[CROSSREF]

3. Xing ZX, Yang H, Zhang W, Wang Y, Wang CS, Chen T, et al. Point-of-care ultrasound for the early diagnosis of emphysematous pyelonephritis: A case report and literature review. World J Clin Cases. 2021 Apr 16;9(11):2584-94. doi: 10.12998/wjcc.v9.i11.2584.[CROSSREF]

4. Chuang PH, Yii CY, Cheng KS, Chou JW, Chen CK, Lin YN. Emphysematous pyelonephritis concurrent with psoas muscle abscess. Intern Med. 2011;50(22):2859-60. doi: 10.2169/internalmedicine.50.6117.[CROSSREF]

5. Yeung A, Cheng CH, Chu P, Man CW, Chau H. A rare case of asymptomatic emphysematous pyelonephritis. Urol Case Rep. 2019 Jul 26;26:100962. doi: 10.1016/j.eucr.2019.100962.[CROSSREF]

6. Sun JN, Zhang BL, Yu HY, Wang B. Severe emphysematous pyelonephritis mimicking intestinal obstruction. Am J Emerg Med. 2015 Dec;33(12):1846.e3-6. doi: 10.1016/j.ajem.2015.04.041.[CROSSREF]

7. Wang YC, Wang JM, Chow YC, Chiu AW, Yang S. Pneumomediastinum and subcutaneous emphysema as the manifestation of emphysematous pyelonephritis. Int J Urol. 2004 Oct;11(10):909-11. doi: 10.1111/j.1442- 2042.2004.00919.x.[CROSSREF]

8. Kourounis G, Lim QX, Rashid T, Gurunathan S. A rare case of simultaneous pneumoperitoneum and pneumomediastinum with a review of the literature. Ann R Coll Surg Engl. 2017 Nov;99(8):e241-3. doi: 10.1308/rcsann.2017.0165.[CROSSREF]

9. Mongha R, Punit B, Ranjit DK, Anup KK. Emphysematous pyelonephritis - case report and evaluation of radiological features. Saudi J Kidney Dis Transpl. 2009 Sep;20(5):838-41.[HTTP]

1. Misgar RA, Mubarik I, Wani AI, Bashir MI, Ramzan M, Laway BA. Emphysematous pyelonephritis: A 10-year experience with 26 cases. Indian J Endocrinol Metab. 2016 Jul-Aug;20(4):475-80. doi: 10.4103/2230-8210.183475.[CROSSREF]

2. Lu YC, Hong JH, Chiang BJ, Pong YH, Hsueh PR, Huang CY, et al. Recommended Initial Antimicrobial Therapy for Emphysematous Pyelonephritis: 51 Cases and 14-Year-Experience of a Tertiary Referral Center. Medicine (Baltimore). 2016 May;95(21):e3573. doi: 10.1097/MD.0000000000003573.[CROSSREF]

3. Xing ZX, Yang H, Zhang W, Wang Y, Wang CS, Chen T, et al. Point-of-care ultrasound for the early diagnosis of emphysematous pyelonephritis: A case report and literature review. World J Clin Cases. 2021 Apr 16;9(11):2584-94. doi: 10.12998/wjcc.v9.i11.2584.[CROSSREF]

4. Chuang PH, Yii CY, Cheng KS, Chou JW, Chen CK, Lin YN. Emphysematous pyelonephritis concurrent with psoas muscle abscess. Intern Med. 2011;50(22):2859-60. doi: 10.2169/internalmedicine.50.6117.[CROSSREF]

5. Yeung A, Cheng CH, Chu P, Man CW, Chau H. A rare case of asymptomatic emphysematous pyelonephritis. Urol Case Rep. 2019 Jul 26;26:100962. doi: 10.1016/j.eucr.2019.100962.[CROSSREF]

6. Sun JN, Zhang BL, Yu HY, Wang B. Severe emphysematous pyelonephritis mimicking intestinal obstruction. Am J Emerg Med. 2015 Dec;33(12):1846.e3-6. doi: 10.1016/j.ajem.2015.04.041.[CROSSREF]

7. Wang YC, Wang JM, Chow YC, Chiu AW, Yang S. Pneumomediastinum and subcutaneous emphysema as the manifestation of emphysematous pyelonephritis. Int J Urol. 2004 Oct;11(10):909-11. doi: 10.1111/j.1442- 2042.2004.00919.x.[CROSSREF]

8. Kourounis G, Lim QX, Rashid T, Gurunathan S. A rare case of simultaneous pneumoperitoneum and pneumomediastinum with a review of the literature. Ann R Coll Surg Engl. 2017 Nov;99(8):e241-3. doi: 10.1308/rcsann.2017.0165.[CROSSREF]

9. Mongha R, Punit B, Ranjit DK, Anup KK. Emphysematous pyelonephritis - case report and evaluation of radiological features. Saudi J Kidney Dis Transpl. 2009 Sep;20(5):838-41.[HTTP]


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