Appearance of Pyelitis Emphysematosa on Computed Tomography.

Pyelitis emphysematosa is a gas-forming infection characterized by gas located within the wall of the collecting system and renal pelvis. There are only 2 reported cases of pyelitis emphysematosa in the literature, neither of which occurred in the era of cross-sectional imaging. Here we present a case of pyelitis emphysematosa occurring in an elderly female with congenital left renal atrophy and chronic right hydronephrosis secondary to ureteropelvic junction obstruction.