[Pseudotumor form of focal acute pyelonephritis]

Two cases of focal acute pyelonephritis presenting with an unusual pseudo-tumoral appearance on CT are reported. The lesions exhibited a focal intra-parenchymal homogeneous round-shape mass without any other parenchymal or perirenal fat CT abnormalities. The final diagnosis of focal acute pyelonephritis was confirmed on following CT scans which demonstrated the total disappearance of the lesions in both cases. This particular appearance of acute focal pyelonephritis which mimicked a renal tumor should be clearly individualized in the terminology based on CT findings.