Diverticulitis with colovesical fistula
This patient had a history of colonic diverticulitis in the past, but no recent memory of acute pain symptoms prior to presentation for this study. The colonic wall thickening is worrisome for adenocarcinoma, but pathology was benign in this case.
What makes this case particularly impressive is the well-defined fistulous tract from the colonic lumen into an extraluminal collection, and through a small defect in the bladder mucosa (reference the annotated images). Additionally, the presence of air within the bladder wall strongly suggests the presence of fistula (which was strongly suspected based on the presentation of pneumaturia and fecaluria).