http://journals.lww.com/jcat/Abstract/2009/09000/Fat_Within_the_Wall_of_the_Urinary_Bladder_.8.aspx
Thickman, David MD

OBJECTIVE: The objective of this paper was to describe the computed tomographic appearance, characteristics, and significance of fat in the wall of the urinary bladder.

METHODS: Twenty-three cases of intramural fat were reviewed. Use of intravenous contrast, sex, and degree of bladder distention were noted. Location of intravesical fat was tabulated.

RESULTS: Intramural fat is typically seen as a thin low-density band along the anterior and superior portions of a partially filled urinary bladder. Most of the cases are in men (90%) and are seen on unenhanced studies (>80%). The prevalence of intramural fat was just less than 2%.

CONCLUSION: Fat within the wall of the urinary bladder can be a normal histological finding that is detected at computed tomography typically in patients with nondistended urinary bladders on unenhanced studies.