CT findings in xanthogranulomatous pyelonephritis with coexistent renocolic fistula.

A case of diffuse xanthogranulomatous pyelonephritis of the kidney with an associated renocolic fistula is reported. Computed tomography demonstrated typical findings with an enlarged poorly functioning kidney with multiple near-water-density masses replacing the renal parenchyma surrounding a central staghorn calculus. A mottled gas collection within the renal parenchyma was secondary to a renocolic fistula rather than a pyogenic abscess.