Renal abscess with initial image presentation of renal cyst characteristics


Hippokratia 2013, 17(3):284

Liu PY 1, 2, Chen WM 3, Shi ZY1
Section of Infectious Diseases, Department of Internal Medicine, Taichung Veterans General Hospital, 2Department of Veterinary Medicine, College of Veterinary Medicine, National Chung Hsing University, 3Division of Urology, Department of Surgery, Taichung Veterans General Hospital, Taichung, Taiwan

Key words: Abdominal abscess, computed tomography, pyelonephritis

Corresponding author: Dr. Zhi-Yuan Shi, Section of Infectious Diseases, Department of Internal Medicine, Taichung Veterans General Hospital, Address: No. 160, Sec. 3, Chung-Kang Rd., 40705, Taichung, Taiwan, tel : +8864235925253083, fax : 886423559016, e-mail:

Dear Editor,

A 55-year-old woman presented with fever, right flank soreness and right costovertebral angle knocking pain. The urinalysis showed pyuria, and urine culture yielded Escherichia coli. Abdominal computed tomography (CT) showed less-enhancement of a mildly enlarged right kidney and a well-defined rounded mass with homogeneous content (Figure 1). The findings were consistent with pyelonephritis and a simple renal cyst which has been noted previously. The patient remained febrile after 5 days of ciprofloxacin and developed upper right abdominal pain with guarding and rebound tenderness. Repeat abdominal CT demonstrated right renal abscess (Figure 2). The patient underwent laparoscopic incision and drainage of renal abscess. She had an uncomplicated postoperative course and was discharged 12 days after admission.

Figure 1: Computed tomography of the kidney, first day, showed a solitary simple cyst with a thin wall.

Figure 2: Computed tomography of the kidney, five days latter, showed a 4-cm renal abscess.

Typical contrast-enhanced CT finding of renal abscess is a lesion with irregular thick-walled cavity that may demonstrate a higher attenuation ring1. Occasionally, a renal cystic lesion, as seen in our patient, may be an initial image presentation of renal abscess2. In this patient, fever duration is an important clue to the diagnosis of renal abscess. Various studies showed most patients with renal abscesses had symptoms that lasts more than three to five days3,4.

Physicians need to consider renal abscess in the differential diagnosis of patients with prolong fever and upper urinary tract infections, even if initial image study does not support the diagnosis.


1. Baumgarten DA, Baumgartner BR. Imaging and radiologic management of upper urinary tract infections. Urol Clin North Am. 1997; 24: 545-569.
2. Yap HJ, Lin CL, Huang CC. Atypical initial manifestation of acute pyelonephritis in continuous image study: renal cystic feature. Ren Fail. 2002; 24: 477-484.
3. Fowler JE Jr, Perkins T. Presentation, diagnosis and treatment of renal abscesses: 1972-1988. J Urol. 1994; 151: 847-851.
4. Thorley JD, Jones SR, Sanford JP. Perinephric abscess. Medicine (Baltimore). 1974; 53: 441-451.