Nonneoplastic kidney diseases in adult tumor nephrectomy and nephroureterectomy specimens: common, harmful, yet underappreciated.

CONTEXT Nonneoplastic kidney diseases, such as arterionephrosclerosis and/or diabetic nephropathy, are commonly encountered in tumor nephrectomy and nephroureterectomy specimens. Although any nonneoplastic kidney disease may be encountered in these resection specimens by chance, additional diseases that may be related to the underlying neoplasm or its treatment regimen include thrombotic microangiopathy, Amyloid A amyloidosis, membranous nephropathy, immunoglobulin A nephropathy, membranoproliferative glomerulonephritis, pauci-immune crescentic glomerulonephritis, focal segmental glomerulosclerosis, minimal-change disease, acute interstitial nephritis, and xanthogranulomatous pyelonephritis. Given the morbidity of chronic kidney disease and the relatively favorable 5-year survival rates for urothelial and renal cell carcinomas, accurate evaluation of the nonneoplastic kidney parenchyma is important. OBJECTIVES We will discuss our approach for evaluating the nonneoplastic kidney parenchyma in tumor nephrectomy and nephroureterectomy specimens. The pathologic features of the aforementioned kidney diseases as well as pertinent references will be reviewed. The identification of glomerular abnormalities, including mesangial sclerosis or hypercellularity, segmental sclerosis, crescent formation, glomerulitis, or glomerular basement membrane alterations, should lead to additional immunofluorescence and electron microscopic studies. Safeguards to ensure that the nonneoplastic parenchyma is not overlooked include adding this important parameter to synoptic reports and obtaining periodic acid-Schiff and/or Jones methenamine silver stains prior to microscopic evaluation of the neoplasm. DATA SOURCES Relevant literature and University of Chicago Medical Center pathology archives. CONCLUSIONS The practicing surgical pathologist should be aware of the importance of both correctly classifying the resected renal or urothelial neoplasm and the concomitant nonneoplastic kidney disease that may be present in these specimens.