Clinical value of pathologic examination of non-neoplastic kidney in patients with upper urinary tract malignancies

Background/Aims: While surgical resection remains the standard of care in the treatment of upper urinary tract malignancies, nephrectomy is a risk factor for the development of chronic kidney disease (CKD). The aim of this study was to determine whether histologic evaluation of non-neoplastic kidney could enable early identification of unrecognized kidney disease and could be of prognostic value in predicting postoperative renal outcomes. Methods: We retrospectively analyzed 51 patients with upper urinary tract malignancies who received uninephrectomy or uninephroureterectomy. A thorough pathologic evaluation of non-neoplastic kidney including special stains, immunofluorescence, and electron microscopic studies was performed. The degree of parenchymal changes was graded from 0 to 15. Results: Of 51 patients, only 13 showed normal kidney pathology. Fifteen patients showed glomerular abnormalities, 14 showed diabetic nephropathy, and 11 showed vascular nephropathy. There was one case each of reflux nephropathy and chronic pyelonephritis. The median histologic score was 5 points. Only 25.4% of patients had ${\leq}3$ points. Score more than 5 was observed in 47.1% of patients. Postoperative estimated glomerular filtration rate (eGFR) at 3 to 36 months were obtained from 90.2% of patients, and of those, 34.8% had de novo CKD. Since no one had CKD in partial nephrectomized patients, we determined risk factors for CKD in radical nephrectomized patients. Cox regression analysis revealed that postoperative AKI, preoperative eGFR, and histologic score of non-neoplastic kidney were the independent predictors for CKD. Conclusions: We conclude that routine pathologic evaluation of non-neoplastic kidney provides valuable diagnostic and prognostic information.