Pathology of emphysematous pyelonephritis: A study of 11 cases

Objective: The objective was to study the pathological features of emphysematous pyelonephritis (EPN). Materials and Methods: A total of 11 nephrectomy specimens of EPN received in the surgical pathology section of a tertiary hospital in a metropolis city during the period 2005-2014 are included in this study. Clinical details were obtained from the patients′ records. All the patients had undergone total nephrectomy. All the specimens were fixed in 10% buffered formalin and processed for paraffin wax sectioning. The sections were stained with hematoxylin and eosin stain. Results: The most common symptoms were fever and costovertebral pain. Diabetes mellitus was present in 9 out of 11 cases and one case had calculus in the pelvis. One patient had underlying diabetes which was undiagnosed during the nephrectomy. Diagnosis of EPN was confirmed by the presence of gas and fluid in the renal tissue by computed tomography. The left kidney (nine cases, 81%) was more frequently affected than the right kidney (two cases, 19%). EPN occurred in 40-60 years of age (mean age 51.5%), and out of 11 patients, 8 (81%) were female. Escherichia coli was the commonly isolated organism from urine. Eight cases were of Type II EPN and three cases were Type I EPN. Histopathologic examination of all the cases of EPN showed acute suppurative (necrotizing) inflammation of renal parenchyma and perirenal tissues associated with vasculitis of vessels and infarction. Conclusion: EPN is most commonly seen in patients with diabetes mellitus, and E. coli is the most common causative organism