Retroperitoneal emphysema caused by a renal abscess: a case report.

We report a case of retroperitoneal emphysema caused by a renal abscess. A 45-year-old man with underlying type 2 diabetes mellitus visited the emergency department with right flank pain and a fever. On physical examination, right costovertebral tenderness in the ipsilateral flank was noted. Leukocytosis and high inflammatory marker levels were observed. Urinalysis showed pyuria and glucosuria. Urine culture was positive for Streptococcus agalactiae. A computed tomography scan of the abdomen showed a focal, low-attenuation lesion in the right kidney with a 3 cm, exophytic, high-attenuation lesion in the right kidney upper pole and gas-containing fluid collection within the retroperitoneal space. The diagnosis was retroperitoneal emphysema caused by a renal abscess. As the vital signs were stable and the patient refused puncture, we decided on a course of antibiotics alone with follow-up without percutaneous drainage or surgery. The patient improved without any complications. This is a rare case of a renal abscess penetrating the renal fascia and progressing to a posterior paranephric emphysema. The patient was treated with antibiotics alone and cured successfully. Early diagnosis and proper treatment are needed, and percutaneous drainage or urgent surgery would be beneficial for such cases depending on the patient's condition.