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Intramural vesicular fat — an uncommon CT finding
Clinical Imaging 36 (2012) 75 – 76
Intramural vesicular fat — an uncommon CT finding Raj Ramabhai Patel, Bruce R. Javors⁎ Bronx-Lebanon Hospital Center, 1650 Grand Concourse, Bronx, NY 10456, USA Received 5 February 2011; accepted 10 April 2011
Abstract We present a case of a 75-year-old male who presented with lower back pain found to have an incidental finding of intramural vesicular fat on an unenhanced computed tomography of the pelvis. This relatively uncommon finding of a normal entity should not be mistaken for other causes of pathology within the urinary bladder. © 2012 Elsevier Inc. All rights reserved. Keywords: Intramural vesicular fat; Computed tomography; Urinary bladder; Chyluria
1. Introduction Fat within the urinary bladder wall is a normal but unusual finding on computed tomography (CT) that should not be mistaken for other pathologic causes of hypodensity within the urinary bladder. We report a case of intramural fat within the urinary bladder and discuss other common causes of hypodensity seen on CT within the urinary bladder. 2. Case report A 75-year-old male presented to our emergency department with a complaint of lower back pain of 1-day duration. The patient denied any trauma, dysuria, hematuria or incontinence. The patient's past medical history included coronary artery disease, hypertension, and benign prostatic hypertrophy. The patient's medications included warfarin, furosemide and tamsulosin. On physical examination, the patient was afebrile with left costovertebral tenderness. The abdominal and neuromuscular examinations were normal. Urinalysis revealed clear yellow urine with a specific gravity ⁎ Corresponding author. Bronx-Lebanon Hospital Center, 1650 Grand Concourse, Bronx, NY 10456, USA. Tel.: +1 718 901 6976; fax: +1 718 518 5224. E-mail address: [email protected] (B.R. Javors). 0899-7071/$ – see front matter © 2012 Elsevier Inc. All rights reserved. doi:10.1016/j.clinimag.2011.04.015
of 1.011 and a pH of 8. The urine total protein, ketones, bilirubin, blood, nitrates and leukocyte esterase were all negative. Both urine glucose and urobilinogen were normal. Computed tomography of the abdomen and pelvis was performed without intravenous or oral contrast to evaluate for renal stones. The CT demonstrated no renal calculus, hydroureter, hydronephrosis or perinephric fat stranding. The urinary bladder was partially distended and demonstrated a thin curvilinear hypodensity along the superior, anterior and lateral walls of the bladder (Fig. 1). The CT number of the hypodensity along the anterior aspect was −78 Hounsfield units. There was no fat-fluid level within the bladder. Comparison to a CT from 4 years prior demonstrated a similar hypodensity along the superior and anterior walls. 3. Discussion Intramural fat of the urinary bladder is a relatively uncommon normal finding on CT that should not be mistaken for other pathologic causes of hypodensity within the bladder wall. To our knowledge, only one prior study has described the CT appearance of fat within the urinary bladder [1]. Thickman presented 23 cases that all demonstrated fat within the anterior wall or dome of the bladder, which correlated with pathologic studies of prominent clusters of adipocytes seen mostly in the dome of the bladder [1,2]. The
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R.R. Patel, B.R. Javors / Clinical Imaging 36 (2012) 75–76
difficult to appreciate [1]. No fat-fluid level is seen within the wall or lumen. Other causes of hypodensity in the bladder or its wall seen on CT include air and chyluria. Air may be seen within the bladder due to noninfectious causes, such as recent instrumentation or catheterization or fistulous connection with the gastrointestinal tract or vagina [4]. In addition, air may be seen within the bladder wall or bladder due to emphysematous cystitis. Emphysematous cystitis is an acute inflammation of the bladder mucosa and overlying musculature with a female predominance. It occurs more frequently in diabetics and is typically associated with gasproducing bacteria, such as Escherichia coli and Enterobacter aerogens, although fungal species are occasionally implicated [5]. Chyluria is the presence of lymph within the urine due to an abnormal connection between lymphatics and the urinary tract [6]. Worldwide, it occurs most commonly due to renal lymphatic obstruction secondary to lymphatic filariasis due to Wuchereria bancrofti or Brugia malayi [7]. In nonendemic areas, more common causes are tuberculosis, tumors, retroperitoneal abscess, pregnancy and surgical trauma [8]. Case reports have also associated chyluria with radiofrequency ablation of renal cell carcinoma [6]. On CT, chyluria demonstrates a fat-fluid level within the bladder lumen rather than the wall and typically measures between −20 and −180 Hounsfield units [6]. Microscopic assessment of the bladder wall determines the pathologic tumor stage of urinary bladder cancer, with involvement of the muscularis propria a key factor in differentiating between the need for conservative vs. aggressive management [2]. However, at the current time, the role of intramural fat in staging bladder cancer is unclear. With increased awareness of the finding of vesicular intramural fat, the radiologist will be less likely to misdiagnosis this finding as bladder pathology. References
Fig. 1. Unenhanced CT of the pelvis. (A) Axial image demonstrates a thin curvilinear hypodensity (arrow) along the anterior wall of the partially distended urinary bladder. Sagittal (B) reformatted image of the bladder demonstrate a thin curvilinear density (arrow) along the dome and anterior portions of the bladder wall. No fat-fluid level is seen.
frequency of intramural fat on CT was reported at 1.4%, which was less than the pathologic reported frequency of 4% [1–3]. Both CT and pathologic studies report a male predominance [1–3]. On CT, intramural fat of the urinary bladder appears as a thin linear hypodensity along the dome and anterior portions of the bladder, which is more frequently seen in partially distended bladders on nonenhanced studies [1]. It is presumed that the bladder wall and fat within the wall becomes thinned in a distended bladder and hence more
[1] Thickman D. Fat within the wall of the urinary bladder: computed tomographic appearance. J Comput Assist Tomogr 2009;33:695–7. [2] Paner GP, et al. Further characterization of the muscle layers and lamina propria of the urinary bladder by systematic histologic mapping: implications for pathologic staging of invasive urothelial carcinoma. Am J Surg Pathol 2007;31:1420–9. [3] Philip AT, et al. Intravesical adipose tissue: a quantitative study of its presence and location with implications for therapy and prognosis. Am J Surg Pathol 2000;24:1286–90. [4] Campbell MF, Wein AJ Kavoussi LR. Campbell-Walsh urology/ editor-in-chief, Alan J. Wein; editors, Louis R. Kavoussi [et al.]. 9th ed. Philadelphia: Saunders; 2007. [5] Grayson DE, et al. Emphysematous infections of the abdomen and pelvis: a pictorial review. Radiographics 2002;22:543–61. [6] Schneider J, et al. Chyluria associated with radiofrequency ablation of renal cell carcinoma. J Comput Assist Tomogr 2010;34:210–2. [7] Singh SK, et al. The case: milky urine. Chyluria. Kidney Int 2008;74: 1100–1. [8] Miller FH, et al. CT diagnosis of chyluria after partial nephrectomy. AJR Am J Roentgenol 2007;188:W25–8.
Intramural vesicular fat — an uncommon CT finding Raj Ramabhai Patel, Bruce R. Javors⁎ Bronx-Lebanon Hospital Center, 1650 Grand Concourse, Bronx, NY 10456, USA Received 5 February 2011; accepted 10 April 2011
Abstract We present a case of a 75-year-old male who presented with lower back pain found to have an incidental finding of intramural vesicular fat on an unenhanced computed tomography of the pelvis. This relatively uncommon finding of a normal entity should not be mistaken for other causes of pathology within the urinary bladder. © 2012 Elsevier Inc. All rights reserved. Keywords: Intramural vesicular fat; Computed tomography; Urinary bladder; Chyluria
1. Introduction Fat within the urinary bladder wall is a normal but unusual finding on computed tomography (CT) that should not be mistaken for other pathologic causes of hypodensity within the urinary bladder. We report a case of intramural fat within the urinary bladder and discuss other common causes of hypodensity seen on CT within the urinary bladder. 2. Case report A 75-year-old male presented to our emergency department with a complaint of lower back pain of 1-day duration. The patient denied any trauma, dysuria, hematuria or incontinence. The patient's past medical history included coronary artery disease, hypertension, and benign prostatic hypertrophy. The patient's medications included warfarin, furosemide and tamsulosin. On physical examination, the patient was afebrile with left costovertebral tenderness. The abdominal and neuromuscular examinations were normal. Urinalysis revealed clear yellow urine with a specific gravity ⁎ Corresponding author. Bronx-Lebanon Hospital Center, 1650 Grand Concourse, Bronx, NY 10456, USA. Tel.: +1 718 901 6976; fax: +1 718 518 5224. E-mail address: [email protected] (B.R. Javors). 0899-7071/$ – see front matter © 2012 Elsevier Inc. All rights reserved. doi:10.1016/j.clinimag.2011.04.015
of 1.011 and a pH of 8. The urine total protein, ketones, bilirubin, blood, nitrates and leukocyte esterase were all negative. Both urine glucose and urobilinogen were normal. Computed tomography of the abdomen and pelvis was performed without intravenous or oral contrast to evaluate for renal stones. The CT demonstrated no renal calculus, hydroureter, hydronephrosis or perinephric fat stranding. The urinary bladder was partially distended and demonstrated a thin curvilinear hypodensity along the superior, anterior and lateral walls of the bladder (Fig. 1). The CT number of the hypodensity along the anterior aspect was −78 Hounsfield units. There was no fat-fluid level within the bladder. Comparison to a CT from 4 years prior demonstrated a similar hypodensity along the superior and anterior walls. 3. Discussion Intramural fat of the urinary bladder is a relatively uncommon normal finding on CT that should not be mistaken for other pathologic causes of hypodensity within the bladder wall. To our knowledge, only one prior study has described the CT appearance of fat within the urinary bladder [1]. Thickman presented 23 cases that all demonstrated fat within the anterior wall or dome of the bladder, which correlated with pathologic studies of prominent clusters of adipocytes seen mostly in the dome of the bladder [1,2]. The
76
R.R. Patel, B.R. Javors / Clinical Imaging 36 (2012) 75–76
difficult to appreciate [1]. No fat-fluid level is seen within the wall or lumen. Other causes of hypodensity in the bladder or its wall seen on CT include air and chyluria. Air may be seen within the bladder due to noninfectious causes, such as recent instrumentation or catheterization or fistulous connection with the gastrointestinal tract or vagina [4]. In addition, air may be seen within the bladder wall or bladder due to emphysematous cystitis. Emphysematous cystitis is an acute inflammation of the bladder mucosa and overlying musculature with a female predominance. It occurs more frequently in diabetics and is typically associated with gasproducing bacteria, such as Escherichia coli and Enterobacter aerogens, although fungal species are occasionally implicated [5]. Chyluria is the presence of lymph within the urine due to an abnormal connection between lymphatics and the urinary tract [6]. Worldwide, it occurs most commonly due to renal lymphatic obstruction secondary to lymphatic filariasis due to Wuchereria bancrofti or Brugia malayi [7]. In nonendemic areas, more common causes are tuberculosis, tumors, retroperitoneal abscess, pregnancy and surgical trauma [8]. Case reports have also associated chyluria with radiofrequency ablation of renal cell carcinoma [6]. On CT, chyluria demonstrates a fat-fluid level within the bladder lumen rather than the wall and typically measures between −20 and −180 Hounsfield units [6]. Microscopic assessment of the bladder wall determines the pathologic tumor stage of urinary bladder cancer, with involvement of the muscularis propria a key factor in differentiating between the need for conservative vs. aggressive management [2]. However, at the current time, the role of intramural fat in staging bladder cancer is unclear. With increased awareness of the finding of vesicular intramural fat, the radiologist will be less likely to misdiagnosis this finding as bladder pathology. References
Fig. 1. Unenhanced CT of the pelvis. (A) Axial image demonstrates a thin curvilinear hypodensity (arrow) along the anterior wall of the partially distended urinary bladder. Sagittal (B) reformatted image of the bladder demonstrate a thin curvilinear density (arrow) along the dome and anterior portions of the bladder wall. No fat-fluid level is seen.
frequency of intramural fat on CT was reported at 1.4%, which was less than the pathologic reported frequency of 4% [1–3]. Both CT and pathologic studies report a male predominance [1–3]. On CT, intramural fat of the urinary bladder appears as a thin linear hypodensity along the dome and anterior portions of the bladder, which is more frequently seen in partially distended bladders on nonenhanced studies [1]. It is presumed that the bladder wall and fat within the wall becomes thinned in a distended bladder and hence more
[1] Thickman D. Fat within the wall of the urinary bladder: computed tomographic appearance. J Comput Assist Tomogr 2009;33:695–7. [2] Paner GP, et al. Further characterization of the muscle layers and lamina propria of the urinary bladder by systematic histologic mapping: implications for pathologic staging of invasive urothelial carcinoma. Am J Surg Pathol 2007;31:1420–9. [3] Philip AT, et al. Intravesical adipose tissue: a quantitative study of its presence and location with implications for therapy and prognosis. Am J Surg Pathol 2000;24:1286–90. [4] Campbell MF, Wein AJ Kavoussi LR. Campbell-Walsh urology/ editor-in-chief, Alan J. Wein; editors, Louis R. Kavoussi [et al.]. 9th ed. Philadelphia: Saunders; 2007. [5] Grayson DE, et al. Emphysematous infections of the abdomen and pelvis: a pictorial review. Radiographics 2002;22:543–61. [6] Schneider J, et al. Chyluria associated with radiofrequency ablation of renal cell carcinoma. J Comput Assist Tomogr 2010;34:210–2. [7] Singh SK, et al. The case: milky urine. Chyluria. Kidney Int 2008;74: 1100–1. [8] Miller FH, et al. CT diagnosis of chyluria after partial nephrectomy. AJR Am J Roentgenol 2007;188:W25–8.