Transverse CT image in a 60-year-old man with fistula formation due to tuberculous colitis. Descending colon appears slightly thickened, and a fistulous tract (white arrows) is shown to extend from the colon to an abscess (black arrow) in the left psoas muscle and through the left paraspinal muscles into the subcutaneous tissue of the back, where another abscess (arrowheads) has formed.

radiology.rsna.org/content/240/3/623.full