Non-neoplastic Pathology in Tumor Nephrectomy Specimens

The Importance of Nephropathology in Kidney Cancer

As early detection and advances in the treatment for renal cell carcinoma continue to lead to excellent oncologic outcomes, the preservation of renal function in kidney cancer patients has emerged as an increasingly important clinical objective. Given that diabetes, hypertension, obesity, cigarette smoking, and aging are independent risk factors for renal cell carcinoma, the corresponding non-neoplastic kidney diseases frequently are present, but often undiagnosed. In addition, the subsequent clinical management of the ensuing chronic kidney disease historically has not included nephrologists. Awareness of these practice gaps remain low among nephrologists, surgeons, and pathologists. This article discusses the common non-neoplastic kidney diseases that are encountered in cancer nephrectomy specimens. The accurate and timely diagnosis of these disorders will result in additional gains in clinical outcomes. There is a unique opportunity for the nephrology community to play a central role in the management of chronic kidney disease that often is present in kidney cancer patients.

Association of Ancillary Pathology Findings in Non-neoplastic Renal Parenchyma and Renal Outcomes of Robotic-Assisted Partial Nephrectomy

Background: To evaluate robotic-assisted partial nephrectomy (RAPN) renal outcomes associated with ancillary pathology findings in non-neoplastic renal parenchymal tissue. Methods: Tissue samples from 378 RAPNs were analyzed for glomerular disease (GD), vascular disease (VD), and tubulointerstitial disease (TD). One hundred and fifty-two patients were excluded due to insufficient non-neoplastic tissue for analysis and 4 patients were excluded due to calyceal diverticulum. Non-neoplastic tissue was evaluated for GD (negative, moderate, or global), VD (absent, mild, moderate, or severe), and TD (present or absent). Associations of ancillary pathology factors with patient characteristics were explored using the non-parametric Kendall tau-test and propensity score adjusted longitudinal mixed effects regression models were used to evaluate associations of these pathology factors with changes in estimated glomerular filtration rate (eGFR) following RAPN. Results: One hundred and fifty-three (68.9%) patients had hypertension and 50 (22.5%) patients had diabetes. The majority of patients did not have any GD (N = 158, 71.2%) or TD (N = 186, 83.8%) while 129 (58.1%) had VD. VD was categorized as absent (N = 93, 41.9%), mild (N = 45, 20.3%), moderate (N = 76, 34.2%), and severe (N = 8, 6.8%). Older age (P = 0.018), hypertension (P < 0.001), and high grade MAP score (P = 0.047) were associated with a higher number of ancillary pathology factors. High grade MAP score (P = 0.03, P = 0.002) and hypertension (P = 0.02, P < 0.001) were individually associated with GD severity and VD severity, respectively. Older age was also individually associated with VD severity (P = 0.002) and hypertension was associated with TD (P = 0.04). Moderate-to-severe VD was associated with a worse change in eGFR from pre-RAPN to 1-month post-RAPN compared to those with mild or no VD (difference in mean change, -3.4 ml/kg/1.73m²; 95% CI, -6.6 to -0.2 ml/kg/1.73m²; P = 0.036). Conclusions: Moderate-to-severe VD in non-neoplastic renal parenchyma is associated with post-operative changes in eGFR. Older age, hypertension, and high grade MAP scores are associated with the number of ancillary pathologies observed in RAPN specimens.

Paraffin Immunofluorescence: A Valuable Ancillary Technique in Renal Pathology

Immunofluorescence on frozen tissue is the gold standard immunohistochemical technique for evaluation of immune deposits in the kidney. When frozen tissue is not available or lacks glomeruli, immunofluorescence can be performed on paraffin tissue after antigen retrieval (paraffin immunofluorescence). Excellent results can be obtained by paraffin immunofluorescence in most immune complex-mediated glomerulonephritides and dysproteinemia-associated kidney lesions, and thus this technique has become a valuable salvage technique in renal pathology. Furthermore, new data have emerged suggesting that paraffin immunofluorescence can be used as an unmasking technique, as it is more sensitive than frozen tissue immunofluorescence in some kidney lesions, such as crystalline light chain proximal tubulopathy and is needed to establish the diagnosis of certain unique lesions, such as membranous-like glomerulopathy with masked IgG kappa deposits and membranoproliferative glomerulonephritis with masked monotypic Ig deposits. However, it is important to recognize and be aware of the limitations and pitfalls associated with paraffin immunofluorescence. These include poor sensitivity for detection of C3 deposits and for the diagnosis of primary membranous nephropathy. Here, we summarize the available techniques of paraffin immunofluorescence, review its role and performance as a salvage and unmasking technique in renal pathology, address its limitations and pitfalls, and highlight unusual forms of glomerulopathy that require paraffin immunofluorescence for diagnosis.

Medical renal diseases are frequent but often unrecognized in adult autopsies

Kidney diseases affect many hospitalized patients and contribute to morbidity and mortality. Therefore, kidney disease should be prevalent, but the frequency and spectrum of medical renal pathology in autopsy specimens has not been well documented. We sought to determine the spectrum of medical renal pathology in adult autopsy specimens and the frequency of overlooked diagnoses. We reviewed the hematoxylin- and eosin-stained kidney sections from 140 adult autopsies performed at a large teaching hospital over a 2-year period. Fifty-eight cases (41%) had findings warranting further analysis, including alterations in glomerular matrix and/or cellularity, atypical or pigmented casts, thrombi, tubulointerstitial or vascular inflammation, or deposition of amorphous material. After additional studies and clinical correlation, the pathologic changes in 43 cases (31%) were categorized as follows: diabetic nephropathy, bile cast nephropathy, thrombotic microangiopathy, infection-related glomerulonephritis, focal necrotizing/crescentic glomerulonephritis, oxalate nephropathy, light-chain cast nephropathy, amyloidosis, urate nephropathy, hemosiderosis, antineutrophil cytoplasmic antibody-associated vasculitis, polyoma virus nephropathy, atheroembolic disease, and nephrocalcinosis. These diagnoses were not reported in 26 (60%) cases during the initial autopsy evaluation. This study demonstrates that medical renal diseases are common in autopsy cases, but significant diagnoses can be easily overlooked. Autopsy kidney specimens are a rich source of renal pathology and their evaluation should be emphasized in anatomic pathology residency training. Ultimately, our understanding of how kidney disease contributes to morbidity and mortality will benefit from accurate recognition of renal pathology in autopsy specimens.

Pathologic analysis of non-neoplastic parenchyma in renal cell carcinoma: a comprehensive observation in radical nephrectomy specimens

Background

This study provides a comprehensive examination of the histological features of non-neoplastic parenchyma in renal cell carcinoma (RCC). We prospectively collected radical nephrectomy (RN) specimens, to analyze the histological changes within peritumoral and distant parenchyma.

Methods

Data of patients who underwent RN and had no known history of diabetes, hypertension, hyperlipidemia, or chronic kidney disease etc., were prospectively collected. Tumor pseudo-capsule (PC), and parenchyma within 2 cm from tumor margin, were pathologically assessed. The parenchyma beyond PC or tumor margin was divided into 20 subsections of 1 mm in width. Histological changes, including chronic inflammation, glomerulosclerosis, arteriosclerosis and nephrosclerosis, were given scores of 0, 1, 2 or 3 for each subsection of each specimen, according to their severity. The 20 subsections of each specimen were further divided into four groups according to the distance from the tumor edge (group 1: 0–2 mm; group 2: 2–5 mm; group 3: 5–10 mm; group 4: 10–20 mm), to better compare the peritumoral parenchyma with the distant parenchyma.

Results

In total, 53 patients were involved in this study. All tumors were confirmed RCCs (clear cell vs. papillary vs. chromophobe were 83% vs. 5.7% vs. 11.3%, respectively), with a mean size of 5.6 cm. Histological changes were more severe in peritumoral parenchyma close to PC or tumor edge (0–5 mm), and less common within parenchyma more distant from the tumor (5–20 mm) (p < 0.001). chronic inflammation and nephrosclerosis were the most common changes especially in peritumoral parenchyma (0-2 mm). PC was present in 49 tumors (92.5%), and PC invasion occurred in 5 cases (10.2%). Mean PC thickness was 0.7 mm. PCs were more likely to be present in clear cell RCC or papillary RCC than in chromophobe RCC (100% vs. 100% vs. 33.3%, respectively; p < 0.001).

Conclusions

Most RCCs have a well-developed PC, especially clear cell RCC. Histological changes mainly occur in peritumoral parenchyma, being rather uncommon in distant parenchyma. A compression band filled with severe histological changes was typically observed in renal parenchyma close to the tumor. Its preservation while performing an enucleation margin may not be entirely necessary.

Electronic supplementary material

The online version of this article (10.1186/s12885-017-3849-5) contains supplementary material, which is available to authorized users.