Nonneoplastic changes are often identified in nephrectomy specimens removed for renal neoplasms. Although they may be of prognostic or therapeutic importance, they are often overlooked. Nephrectomy is also performed for nonneoplastic lesions, the most frequent of which are urinary obstruction and end-stage renal disease, but the tissue diagnosis of these conditions and the implicated clinicopathologic correlation may not be well appreciated.
To outline these nonneoplastic lesions with special attention to important diagnostic caveats and clinicopathologic correlations.
The presented information was derived from literature, personal experience, and review of case materials at the authors' institutions.
Nonneoplastic lesions are seen in most (90%) nephrectomy specimens removed for renal neoplasms. Although these lesions span the spectrum of "medical" kidney diseases, the most frequent of them are hypertensive nephrosclerosis and diabetic nephropathy. Recognition of these diseases is important because they are often first diagnosed and later confirmed clinically. Furthermore, the severity of these lesions may predicate both short- and long-term renal function and thus help guide treatment. Among conditions that necessitate nephrectomy, advanced urinary obstruction, end-stage renal disease, and end-stage renal disease with acquired cystic changes are probably the most frequent. These conditions have characteristic morphologic features, but they may be associated with superimposing lesions previously not well described. These superimposing lesions may create diagnostic confusion; yet, some of them are the reason for nephrectomy. Thus, acute bacterial infection, urine polyp, granulomatous pyelitis, papillary necrosis, massive bleeding, and renal dysplasia can develop against the background of obstructive nephropathy. Renal neoplasms may develop from the background of end-stage renal disease without cystic changes. A renal neoplasm or massive bleeding with or without neoplasm is usually the reason for nephrectomy in kidney with acquired cystic kidney diseases. Thus, while nonneoplastic changes are frequent in nephrectomy specimens, they are often unrecognized. Awareness of these conditions and a familiarity with their diagnostic features as well as the implicated clinicopathologic correlation should help obviate this diagnostic problem.