Emphysematous pyelonephritis— conversion of type i to type II appearance on serial CT studies

Recently, emphysematous pyelonephritis (EPN) has been classified into two subtypes based on CT findings. We recently experienced a patient whose CT image changed from type I (extensive destruction of the renal parenchyma with a large amount of air density without any fluid collection) to type II (containing a large amount of fluid) during the course of conservative treatment. We believe that some patients with type I EPN can change to type II EPN.