Renal oncocytoma

Diagnosing Oncocytoma by Core Needle Biopsy: A Single-Center Experience

Background

Oncocytoma is one of the most common benign kidney tumors, accounting for 3–7% of all solid renal masses. Diagnosing oncocytomas using renal biopsy remains a controversy in the uro-pathologic community. With the increasing use of biopsies for assessment of renal lesions, reaching this pathologically benign diagnosis may prevent further surgical measures and have significant clinical benefit.

Objective

To demonstrate our center's results using renal biopsy to diagnose oncocytomas and to suggest that this diagnosis can be made with high success rates.

Design

, Setting, and Participants. From our center's database, we retrospectively identified and retrieved all cases of oncocytoma diagnosed between the years 2011 and 2020 by renal biopsy. Medical records of those patients were then reviewed to view follow-up meetings and imaging of the lesions biopsied. Outcome Measurements and Statistical Analysis. In 21 biopsies performed on 19 patients, diagnosis was supported by subsequent follow-up averaging at 3.44 years per patient. Results and Limitations. The lesions exhibited benign behavior during follow-up after biopsy, consistent with the diagnosis of oncocytoma.

Conclusions

Our study demonstrates that with good patient selection and proficient cooperation between urologists, radiologists and dedicated uro-pathologists, correctly diagnosing oncocytomas using RCB is a viable task. Patient Summary. Oncocytomas are benign lesions of the kidney. In our study, we reviewed all cases of oncocytomas pathologically diagnosed using renal biopsy from our center's database. We found that in subsequent follow-up later to biopsy, the lesions displayed benign behavior consistent with oncocytoma. The use of percutaneous biopsies to reach this diagnosis could save patients more extensive surgeries.

Molecular pathology of renal oncocytoma: a review

Differentiating renal oncocytoma from its renal cell carcinoma (RCC) mimics, particularly chromophobe RCC, can be difficult, especially when limited tissue is available for evaluation and requires sophisticated microscopic, ultrastructural and immunohistochemical evaluation. In this review, the relevant literature has been reviewed, and supporting data obtained by applying modern microarray-based technologies are discussed with a focus on molecular pathology of renal oncocytoma. The high resolution whole-genome DNA-microarray based analyses excluded with all certainty the occurrence of small specific alterations. Renal oncocytomas are characterized by variable chromosomal patterns. The number of genes selected by global gene expression analyses and their usefulness in the diagnostic pathology based on immunohistochemical evaluation is far below the expectations. The conflicting staining patterns, together with the poor specificity of proposed antibodies, leads us to believe that these candidate immunomarkers might not help in the separation of these tumors. Applying DNA based tools might help in the diagnosis of renal oncocytoma with uncertain histology. However, only the combination of all available techniques could give reliable information.

Differential SP220K expression in renal carcinoma and oncocytoma cells

SP220K is a newly described serine proteinase which displays guanidinobenzoatase activity in its inactive form and gelatinolytic activity in its active form. SP220K expression was studied in 20 renal clear-cell carcinomas and in a series of renal oncocytomas, a rare benign tumor derived from the kidney tubule epithelium. We provide evidence that SP220K expression, as assessed by guanidinobenzoatase activity, gelatin zymography and Western blot immunodetection, was increased markedly in cancer basolateral membranes compared to kidney cortex controls, whereas no signal was detectable in basolateral membranes from the 5 renal oncocytomas studied. Cytoplasms of carcinoma cells were immunodetected consistently, whereas no expression was seen in oncocytic cells from any of the oncocytomas studied (12/12). Endothelial cells were immunodetected in all 3 tissue types. Our data favor a potential mechanistic relationship between expression of the matrix proteinase SP220K and invasive phenotype in kidney epithelium proliferative processes.

Renal oncocytoma: clinical and biological correlates

We treated 31 patients with renal oncocytoma. Renal cell carcinoma was found existing separately within the same or contralateral kidney in 10 patients (32%). Followup of 29 patients revealed 24 alive with no evidence of disease and 1 alive with recurrent oncocytoma, while 1 with coexistent tumors died of progressive renal cell carcinoma and 3 tumor-free patients died of unrelated diseases. Quantitative deoxyribonucleic acid analysis was performed on cell suspensions of fresh tumor by flow cytometry or by image cytometry on touch preparations from frozen tissue in 16 patients with renal oncocytoma. Ploidy analysis revealed all oncocytomas to be diploid. Frozen tissue immunohistology was performed using murine monoclonal antibody against human HLA-A, B and C (class I) antigens with the avidin-biotin peroxidase technique in 11 patients with renal oncocytoma. Ten oncocytomas did not express these self-recognition antigens and 1 was only weakly positive for antigen expression. In contrast, renal cell carcinomas strongly expressed HLA class I antigens. The high incidence of coexistence of renal oncocytoma and renal cell carcinoma has important clinical implications. Loss of HLA class I antigen expression by renal oncocytomas may provide an additional method for differentiating this lesion from renal cell carcinoma.

Cytogenetic abnormalities in renal oncocytic neoplasms

We have performed cytogenetic studies on five renal oncocytic neoplasms (three grade 2 tumors and two grade 1 tumors) identified histologically by light microscopy. One grade 1 tumor failed to produce mitotic cells. The other four tumors exhibited both normal and abnormal cell lines. Numerical abnormalities were found in both the single grade 1 and two of the grade 2 tumors whereas structural abnormalities were limited to grade 2 tumors. Aneuploidy of chromosome 12 was observed in both grade 1 and 2 tumors. Grade 2 tumors showed more extensive numerical change than the grade 1 tumors. Abnormalities of chromosome 3 characteristic of renal cell carcinoma were not found in any tumor in this series. A combination of C-banding and HaeIII endonuclease banding was used to identify an ambiguous marker. In our four cases and in the cases previously reported, loss of a sex chromosome, abnormalities of chromosomes 1 and 22, and trisomy 12 are findings most often observed in renal oncocytoma.

Molecular analysis of the short arm of chromosome 3 in five renal oncocytomas

Renal oncocytomas were tested for loss of alleles at loci on the short arm of chromosome 3, a genetic change characteristic of human renal cell carcinoma. Five renal oncocytomas did not show loss of alleles at loci on 3p supporting the view that renal oncocytoma is a distinct form of renal neoplasia.

Conservative surgical treatment of renal cell carcinoma: clinical experience and reappraisal of indications

During a 14-year period 36 patients who presented with renal cell carcinoma underwent conservative surgical treatment. The patients were divided into 3 groups according to treatment indications and condition of the contralateral kidney: group 1 included patients with a solitary kidney or bilateral tumors, group 2 patients had a damaged contralateral kidney and group 3 patients were without abnormalities of the contralateral kidney. Cumulative 6-year survival rates were 58 per cent for group 1, and 90 per cent for groups 2 and 3 combined. The over-all cumulative 6-year survival rate was 74 per cent. Based on these data extension of the indication for conservative surgical treatment seems to be justified in patients who present with low stage tumors and partial or potential damage to the contralateral organ.