CASE 12029 Published on 18.08.2014

CT appearance of renal abscess

Section

Uroradiology & genital male imaging

Case Type

Clinical Cases

Authors

Dagmara Wilmanska

Hospital of the Ministry of Interior,
Polnocna 42, 90-720 LODZ,
Poland; wilmanska@onet.pl

Patient

63 years, male

Categories

Area of Interest Abdomen, Kidney, Lymph nodes ; Imaging Technique CT, Catheter venography

Procedure Contrast agent-intravenous ; Special Focus Abscess, Infection, Inflammation ;

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Clinical History

63-year-old man with a history of low fever, nausea, weight loss and chronic constipation was referred for a CT examination by his surgeon who found a mass in the left lumbar region on palpation. The ambulatory ultrasound showed a hypoechoic round lesion within the left kidney.

Imaging Findings

Multiphase CT was performed. Unenhanced CT demonstrated a 7-cm left kidney mass of fluid attenuation with small gas bubbles and surrounded by thick, irregular wall. Other findings included thickening of surrounding fascia and obliteration of perinephric fat tissue. Contrast-enhanced CT revealed contrast-enhancement of the cystic mass pseudocapsule, with no enhancement of its cystic parts. The mass pressed and displaced the adjacent renal parenchyma which otherwise appeared normal in all phases but one. Excretion of both kidneys was normal.

Discussion

CT findings are consistent with a diagnosis of a renal abscess.

Renal abscess is a localised collection of infective fluid resulting from the spread of infection process usually from the upper urinary tract, often diagnosed in immunocompromised and diabetic patients. Proper diagnosis is essential for introducing treatment with antibiotics and drainage as fast as possible to avoid abscess rupture into the calyceal system or outside the kidney - into the perinephric space or peritoneum.
Ultrasound as a first-line tool can detect a rounded hypoechoic mass within the renal parenchyma.
CT is the best technique to evaluate the disease [1, 2, 3]. Typical findings include a hypodense, cystic rounded mass with irregular, thick capsule; the lesion may contain gas bubbles and shows contrast enhancement of the pseudocapsule. Associated features include fascial thickening and adjacent fat tissue obliteration.
MRI can be the modality of choice for patients allergic to iodine contrast media and can be an alternative to avoid radiation exposure in younger patients, but radiologist must be aware of difficulties in depicting gas bubbles and stones on MRI images [4].

Differential Diagnosis List

Renal abscess

Renal cell carcinoma

Renal complex cyst

Final Diagnosis

Renal abscess

References

[1] Kauczor HU1, Schwickert HC, Schweden F, Schild HH, Thelen M. (1994) Bolus-enhanced renal spiral CT: technique, diagnostic value and drawbacks. Eur J Radiol 1994 Aug;18(3):153-7 (PMID: 7957283)

[2] Kawashima A1, Sandler CM, Ernst RD, Goldman SM, Raval B, Fishman EK. (1997) Renal inflammatory disease: the current role of CT. Crit Rev Diagn Imaging Oct;38(5):369-415 (PMID: 9391748)

[3] Browne RF1, Zwirewich C, Torreggiani WC. (2004) Imaging of urinary tract infection in the adult. Eur Radiol Mar;14 Suppl 3:E168-83 (PMID: 14749952)

[4] Sergio Savastano, Alessandra Costantini, Davide Dal Borgo, Stefano Trupiani, Stefano Da Pozzo, Andrea Busolo (2011) US, MRI and DW-MRI findings of a renal abscess. 10.1594/EURORAD/CASE.9681

Case information

URL:	https://eurorad.org/case/12029
DOI:	10.1594/EURORAD/CASE.12029
ISSN:	1563-4086

Figure 1

Non-contrast CT images

Non-contrast axial CT image showing hypodense mass of fluid attenuation, containing gas and surrounded by thick wall. Obliteration of adjacent fat tissue and thickening of surrounding fascia is also noted.

Non-contrast coronal CT image showing hypodense mass of fluid attenuation, containing gas and surrounded by thick wall. Obliteration of adjacent fat tissue and thickening of surrounding fascia is also noted.

Figure 2

Contrast-enhanced CT images