Cytogenetic analysis of six renal oncocytomas and a chromophobe cell renal carcinoma. Evidence that -Y, -1 may be a characteristic anomaly in renal oncocytomas.

Renal oncocytomas are benign tumors whose morphologic features may sometimes be confused with those of certain low-grade malignant neoplasms of the kidney, e.g., chromophobe cell and granular cell variants of renal carcinoma. The presence of a specific genetic abnormality might help differentiate these tumors. Because very few cytogenetic studies of renal oncocytomas have been published, we investigated a consecutive series of six such tumors. We also performed chromosome analysis on a chromophobe cell carcinoma because cytogenetic analyses of this tumor have not been previously reported. Tumor cell metaphases were analyzed after mechanical and enzyme disaggregation, in situ culture, and robotic harvesting. Clonal abnormalities were present in five of the six oncocytomas, and loss of chromosome 1 with loss of the Y chromosome occurred in two. Review of the literature disclosed four other renal oncocytomas with the 44,X,-Y,-1 karyotype. In the chromophobe cell carcinoma, we noted an abnormal clone with a del(11)(p12p15.1); similar anomalies were not observed in the renal oncocytomas. We conclude that renal oncocytomas have clonal chromosome abnormalities and that a subgroup of these tumors may be specifically associated with loss of chromosomes 1 and Y. Because this is a small series, further investigation may help establish whether cytogenetic studies can provide diagnostic and pathogenic information about renal oncocytomas.     

Loss or reduction of Fhit expression in renal neoplasias: correlation with histogenic class

Involvement of the 3p14.2 region of chromosome 3 in kidney cancers was suggested 20 years ago, when a reciprocal constitutional translocation, t(3;8)(p14.2;q24), was shown to segregate with bilateral clear cell renal carcinoma in 3 generations of 1 family. The FHITgene that is interrupted at 3p14.2 by the t(3;8) translocation has been isolated, characterized, and shown to be frequently altered, mainly by internal deletion, in carcinomas or cancer-derived cell lines of the lung, stomach, pancreas, esophagus, cervix, and colon. Although up to 90% of sporadic clear cell renal carcinomas, representing 70% of adult renal carcinomas, exhibit loss of FHIT alleles, FHIT gene alterations have been documented for only a few renal cell carcinoma-derived cell lines. Nevertheless, more than 50% of clear cell carcinomas were recently shown to express little or no Fhit protein, unlike the normal kidney tubule epithelium, which is uniformly strongly positive for Fhit expression. We have extended our immunohistochemical study of expression of Fhit protein to the spectrum of histopathologic subtypes of adult renal tumors. There is an apparent continuum of Fhit expression from the 100% strongly positive oncocytomas through mostly positive papillary and chromophobe to the mostly negative clear cell and sarcomatoid to the negative or predominantly negative collecting duct renal carcinomas. This pattern of diminishing Fhit expression correlates with reported frequency of 3p allele loss in renal carcinomas and may parallel the potential for aggressive behavior of tumors, as suggested by the abundant Fhit expression in the benign oncocytomas and the near absence of Fhit expression in sarcomatoid and collecting duct RCCs.     

Loss of chromosome 9p is an independent prognostic factor in patients with clear cell renal cell carcinoma.

Loss of chromosome 9p has been implicated in the progression of renal cell carcinoma. We evaluated the clinical utility of fluorescence in situ hybridization analysis of loss of chromosome 9p in 73 patients with clear cell renal cell carcinomas with varied stage, size, grade, necrosis (SSIGN) scores. Loss of chromosome 9p was observed in 13 tumors (18%). The 5-year cancer-specific survival of patients without loss of chromosome 9p was 88% and was 43% in those with loss of chromosome 9p (P<0.001). Local extension of the primary tumor according to the 2002 TNM staging system, lymph node involvement, the presence of distant metastases, and the SSIGN score were the other variables that predicted cancer-specific survival in univariate analysis. Loss of chromosome 9p was an independent prognostic factor in multivariate analysis. Our data indicate that the detection of chromosome 9p loss by fluorescence in situ hybridization analysis of clear cell renal cell carcinoma adds prognostic information beyond the pathological factors included in the current predictive models for renal cell carcinoma, such as SSIGN score.     

Cytogenetic characterization of 22 human renal cell tumors in relation to a histopathological classification.

In this study, cytogenetic and fluorescence in situ hybridization analyses were performed on 22 sporadic, unilateral primary renal cell tumors. The tumors were classified according to cell types, growth patterns, and grades of malignancy. A feeder layer technique was used for the cell culture of 13 clear-cell carcinomas, 4 chromophilic carcinomas, 3 chromophobe carcinomas, 1 oncocytoma, and 1 spindle-shaped pleomorphic carcinoma. Eighty-six percent (19/22) of renal tumors showed clonal abnormalities. The most frequent finding in the 15 male patients was loss of chromosome Y (9/15). In 3/15, it was the only observed aberration. The second most visible aberration was regional loss or entire loss of chromosome 9, which was detected in 36% (8/22) of the cases. Four cases showed loss of chromosome 9 and 4 cases a deletion of the short arm with breakpoints on 9p11 and 9p21. Loss of 3p material was observed in 32% (7/22) of the cases but only in 2/13 patients with clear-cell carcinoma. Gain of chromosome 12 or 12p was observed in 27% (6/22). In 23% (5/22) of the patients, gain of whole or partial chromosomes 2, 5, and 7 was found. Less-frequent findings were loss of chromosomes 8, 14, and 21; gain of chromosome 16; and structural abnormalities of chromosome 1 (each 18%; 4/22). Only some of the karyotypes described as typical for the various renal tumor types were confirmed. In contrast with previous reports, chromosome 3 and 9 aberrations did not allow differentiation between tumor types in our study.     

A case of liver metastasis from an oncocytoma with a focal area of chromophobe renal cell carcinoma: a wolf in sheep's clothing

In 2004, the World Health Organization classified the renal oncocytomas as benign neoplasms of the kidney. There are reports of subtypes of renal tumors, with similar histological morphology to oncocytoma, but with malignant potential, one of these tumors is the eosinophilic variant of chromophobe renal cell carcinoma. It is important to characterize the histological features and the subtype of tumor, as this predicts biological behavior and cancer-specific survival rate. A rare case of a liver metastasis from a focal area of eosinophilic variant of chromophobe renal cell carcinoma mixed in oncocytoma in a 69-year-old woman is reported. Although some renal tumors may contain oncocytoma and eosinophilic variant of chromophobe renal cell carcinoma histology, caution should be exercised while diagnosing oncocytomas in needle biopsies as there may be unsampled area of chromophobe carcinoma which has a potential for metastatic spread representing a wolf in sheep's clothing.     

Renal oncocytoma. A phenotypic and genotypic entity of renal parenchymal tumors.

The light and electron microscopic morphology of two renal parenchymal tumors was consistent with the diagnosis of renal oncocytoma. Both tumors had a mosaic chromosome pattern of cells with normal and abnormal karyotypes. No recurrent chromosome aberration and also no rearrangement of chromosome 3p was found. Restriction analysis of the mitochondrial DNA revealed a new autoradiographic band at about 50 basepairs in size occurring exclusively in oncocytomas. The possible use of these findings in the diagnosis of renal oncocytomas is discussed.     

Genomic defects in nonfamilial renal cell carcinoma. Possible specific chromosome change

Using a newly developed combined method of enzymatic technique and short-term tissue culture, 30 tumor specimens from 26 patients with nonfamilial renal cell carcinoma were subjected to cytogenetic analysis. Of the 26 patients, 19 had chromosomally abnormal tumors, four (including two oncocytomas) were normal, and three did not grow. The modal chromosome numbers ranged from 44 to 98 (including two pseudotetraploids). Banding analysis revealed 38 clonal aberrations and ten nonclonal aberrations. Abnormalities were of structure and number. The most consistent clonal abnormality was a trisomy or tetrasomy chromosome 7 occurring in tumors from 15 of the 19 patients with cytogenetically abnormal tumors. In four cases, trisomy 7 was the only visible abnormality observed, and in an additional five it was the only abnormality in two or more cells. An abnormal chromosome 3 was found in ten (38%) of the cases. Two were trisomic for #3, two were monosomic, three were hyperdiploid, and three had interstitial deletions with breakpoints clustered from p11 to p25. In only one case was a deleted #3 the only abnormality observed in a clone of cells. Loss of the sex chromosome was seen in eight (35%) of the 23 chromosomally abnormal cases including all four (100%) patients with bilateral disease. One of the patients with bilateral disease had an abnormal clone with monosomy X as the only abnormality. These data suggest that trisomy or tetrasomy 7 more often represents the specific primary abnormality than abnormalities of either chromosome 3 or the sex chromosomes. From this, a model of chromosomal progression may be constructed for nonfamilial renal cell carcinoma, which could assist in pathologic classification and prognostic and therapeutic considerations.     

PTEN expression in renal cell carcinoma and oncocytoma and prognosis

AIMS: Deletion or inactivation of the tumour suppressor gene PTEN (phosphatase and tensin homologue deleted from chromosome 10) contributes to tumorigenesis in a variety of human carcinomas. The present study evaluated PTEN expression in renal cell carcinomas and oncocytomas. METHODS: A tissue microarray from 493 specimens including renal cell carcinomas (n = 440), oncocytomas (n = 21) and tumour-negative renal tissue (n = 32) from patients (n = 461) was incubated with an anti-PTEN antibody for subsequent analysis of PTEN expression. Furthermore, the effect of PTEN expression on the survival of renal carcinoma patients was evaluated. RESULTS: Renal cell carcinomas, and even more pronouncedly oncocytomas, expressed PTEN predominantly in the cytoplasm. In contrast to oncocytomas, PTEN expression was typically decreased in renal cell carcinoma subtypes. PTEN expression in sarcomatoid renal cell carcinomas was comparable to that in non-sarcomatoid subtypes. The PTEN expression pattern had no significant influence on prognosis. CONCLUSIONS: Renal tumours (renal cell carcinomas and oncocytomas) express PTEN protein predominantly in the cytoplasm. A reduction in PTEN expression appears to be an early step in renal cell carcinogenesis. However, the PTEN expression pattern of renal cell carcinomas apparently is not prognostic for patient survival.     

Loss of heterozygosity studies indicate that chromosome arm 1p harbors a tumor suppressor gene for renal oncocytomas

We carried out a complete genome scan for loss of heterozygosity (LOH) in four renal oncocytomas by using highly polymorphic CA repeat microsatellite loci. Three of the four tumors exhibited LOH for chromosome arm 1p, and the oncocytomas of both female patients lost Xq. Therefore, these chromosome arms may harbor tumor suppressor genes involved in the etiology of this disease. Although the genomes of oncocytomas are relatively stable, two different microsatellite loci in one tumor were mutated by ±2 nt. Similar alterations in CA repeats that are probably due to spontaneous mutation have been observed in renal cell carcinomas. Genes Chromosom Cancer 16:64–67 (1996). © 1996 Wiley-Liss, Inc.     

Carbonic anhydrase IX expression in renal neoplasms: correlation with tumor type and grade

Carbonic anhydrase IX (CAIX), a hypoxia-induced protein, is expressed in some renal tumors. We evaluated its immunohistochemical expression in 317 primary and 42 metastatic renal neoplasms (186 clear cell, 52 papillary, 35 chromophobe, 47 unclassified, and 15 Xp11.2 translocation renal cell carcinomas [RCCs]; 26 oncocytomas; 2 metanephric adenomas; 1 urothelial carcinoma; 1 mixed epithelial and stromal tumor; and 1 angiomyolipoma); 7 neoplasms were unknown as to whether they were primary or metastatic. We also correlated expression with tumor type and grade. Variable staining was seen in clear cell, papillary, unclassified, and Xp11.2 translocation carcinomas. One chromophobe carcinoma had focal expression. No staining was seen with other tumors. An association was found between high expression and clear cell vs non-clear cell carcinomas with all cases (P < .01) and primary (P < .01) cases. An association between CAIX expression and grade (P < .01) in primary clear cell carcinomas was found. CAIX expression is more common in clear cell RCC than other renal tumor types and is associated with grade.     

Cytogenetic alterations in renal tumors: a study of 38 Southeast Asian patients

Renal cell carcinoma (RCC) is the most common cancer of the kidney. Cytogenetic studies of renal cell carcinoma have provided valuable insight into the chromosomal abnormalities involved in the genesis and progression of the disease, and have also helped in the classification of these tumors. Our objectives were to identify nonrandom chromosome abnormalities in renal tumors in a Southeast Asian population and also to determine if they differ from those in Western populations. Structural rearrangements of 3p were specific for clear cell RCC, with the most consistent structural rearrangement being a translocation between 3p13 and 5q22. Gains of chromosomes 7 and 17 were observed in three and two cases of papillary RCC, respectively. All male patients with papillary RCC were noted to have loss of the Y chromosome. Gains of chromosomes 3 and 7, and structural aberration of chromosome 3, were observed in patients with transitional cell carcinoma of the renal pelvis (TCC). Chromosomal abnormalities in clear cell RCC, papillary RCC, and TCC did not differ between the Southeast Asian and Western populations. The aberrations seem to be common sporadic events, both geographically and racially.     

Allelic loss at 10q23.3 but lack of mutation of PTEN/MMAC1 in chromophobe renal cell carcinoma.

Chromophobe renal cell carcinoma (RCC) is characterized by loss of multiple chromosomes including chromosome 10. This study was undertaken to determine the LOH at the PTEN/MMAC1 locus (chromosome band 10q23.3) and to search for gene mutations in 15 chromophobe, 50 conventional, and 10 papillary RCCs as well as in 10 renal oncocytomas. Loss of heterozygosity (LOH) wa seen at all informative loci in all chromophobe RCCs and in two conventional RCCs. We did not find mutations by analyzing exon 1 to 9 of the PTEN/MMAC1 gene using the PCR-SSCP technique in tumors with LOH at 10q23.3.     

Parvalbumin is constantly expressed in chromophobe renal carcinoma.

Chromophobe renal carcinoma is composed of neoplastic cell showing several features similar to those found in the intercalated cells of the collecting ducts. Because the distal nephron expresses calcium-binding proteins playing a role in calcium homeostasis, we reasoned that these proteins could be expressed by chromophobe carcinoma and therefore represent a diagnostic marker. We studied the immunohistochemical expression of different calcium-binding proteins (parvalbumin, calbindin-D28K, and calretinin) in 140 renal tumors, including 75 conventional (clear cell) carcinomas, 32 chromophobe carcinomas, 17 papillary renal cell carcinomas, and 16 oncocytomas. Parvalbumin was strongly positive in all primary chromophobe carcinomas and in one pancreatic metastasis; it was positive in 11 of 16 oncocytomas and absent in conventional (clear cell) and papillary renal cell carcinomas, either primary or metastatic. Calbindin-D28K and calretinin were negative in all tumors, with the exception of two chromophobe carcinomas, four oncocytomas, and two papillary renal cell carcinomas showing inconspicuous calretinin expression. Our data demonstrate that parvalbumin may be a suitable marker for distinguishing primary and metastatic chromophobe carcinoma from conventional (clear cell) and papillary renal cell carcinoma. Moreover, they suggest a relationship between chromophobe renal carcinoma and renal oncocytoma and indicate that chromophobe carcinoma exhibits differentiation toward the collecting-duct phenotype.     

Renal oncocytoma with loss of chromosomes Y and 1 evolving to papillary carcinoma in connection with gain of chromosome 7. Coincidence or progression?

Hybrid tumors of the kidney are not rare. Previous studies of hybrid renal tumors have been valuable for the understanding of the pathogenesis and progression pathways of renal cell neoplasm. In this paper we describe the morphologic, immunohistochemical, and genetic features of 2 oncocytomas with evolving papillary renal cell carcinoma (PRCC) in a nephrectomy specimen of a 60-year old male. The patient was referred for urologic oncology consultation after the incidental discovery of a renal tumor. Nephrectomy was performed and two separate masses were present grossly. The tumors were stained with hematoxylin and eosin, cytokeratin 7 and vimentin. Genetic studies included conventional metaphase cytogenetics and fluorescence in situ hybridization (FISH). Morphologically, both tumors were oncocytomas with numerous microscopic papillary nests and psammoma bodies. Papillary carcinoma nests were highlighted with cytokeratin 7 and vimentin positivity and were more prominent in the larger tumor. Conventional cytogenetics and FISH demonstrated loss of chromosomes Y and 1 and gains of chromosome 7. We postulate that the PRCC represents a neoplastic progression by the gain of chromosome 7 oncocytoma with -Y and -1.     

Analysis of chromosome 1p abnormalities in renal oncocytomas by loss of heterozygosity studies: correlation with conventional cytogenetics and fluorescence in situ hybridization

We previously showed by cytogenetics and fluorescence in situ hybridization (FISH) that the most common chromosomal abnormality in renal oncocytomas is loss of chromosome 1 or 1p. In the present study, we evaluated chromosome 1 by loss of heterozygosity (LOH) studies. DNA was extracted from paraffin sections. Three microsatellite markers were used: D1S508, D1S199, and D1S2734. The regions targeted by FISH probes and LOH markers were close to each other but not overlapping.Among 16 tumors evaluated by all 3 techniques, in 2 cases, LOH could not be interpreted. LOH was detected in at least 1 locus in 12 (86%) of 14 renal oncocytomas studied, with other loci being noninformative or not interpretable (1 case). In 2 cases, the LOH results were inconclusive.These results provide further evidence to support widespread abnormalities in chromosome 1p in renal oncocytoma. Determining whether such abnormalities are unique to renal oncocytomas or are also present in other tumors requires further studies.     

Overexpression of KIT (CD117) in chromophobe renal cell carcinoma and renal oncocytoma

KIT expression has not been studied substantially in renal tumors. We analyzed the immunohistochemical expression for KIT in 256 conventional renal cell carcinomas (RCCs), 29 chromophobe RCCs, 25 papillary RCCs, 6 collecting duct RCCs, 6 unclassified RCCs, 7 renal oncocytomas, 20 urothelial carcinomas, 7 nephroblastomas, and 23 angiomyolipomas. We found that 24 chromophobe RCCs (83%) and 5 renal oncocytomas (71%) revealed membranous immunoreactivity for KIT while none of the RCCs of other types expressed KIT immunohistochemically. Sporadic cases of urothelial carcinoma and nephroblastoma were focally positive for KIT. All angiomyolipomas were negative. Genomic DNA extracted from the chromophobe RCCs and renal oncocytomas was submitted for polymerase chain reaction and direct sequencing of the juxtamembrane (exons 9 and 11) and tyrosine kinase (exons 13 and 17) domains. No mutation was found. Our results demonstrate that KIT could be a useful immunophenotypic marker for chromophobe RCC and renal oncocytoma; therefore, it has value for the precise classification of renal cortical epithelial tumors. However, the therapeutic relevance of KIT overexpression in these tumors is uncertain owing to the lack of mutations that would lead to constitutive activation of the protein.     

Molecular differential diagnosis of renal cell carcinomas by microsatellite analysis.

Recent application of molecular cytogenetic techniques has resulted in a new type of genetic classification of renal cell tumors. The key aspect of the novel diagnostic concept is reflected by biologically distinct entities, each characterized by a specific combination of genetic changes. To work out a diagnostic/prognostic approach, we have applied polymorphic microsatellite markers for a quick analysis, based on polymerase chain reaction, of 82 tumor specimens. We compared the results to previously evaluated cytogenetic and histological data. All nonpapillary and chromophobe renal cell carcinomas, which make up approximately 90% of all malignant renal cell tumors, and a subset of renal oncocytomas were correctly diagnosed by detection of loss of heterozygosity at chromosomal sites 1, 2, and 3p. Allelic losses at chromosomal regions 8p, 9p, and 14q are associated with an advanced pathological stage of nonpapillary renal cell carcinomas. A loss of heterozygosity at chromosomes 6, 10, 13, 17, and 21, in addition to those at chromosomes 1 and 2, confirm the diagnosis of chromophobe renal cell tumors. Using this approach, the differential diagnosis of renal cell tumors could be carried out within 1 or 2 days.     

The genetics of renal oncocytosis: a possible model for neoplastic progression

Renal oncocytosis is a rare condition characterized by the presence of numerous oncocytomas and oncocytic changes in the renal tubules. Other than oncocytomas associated with the Birt-Hogg-Dube (BDH) syndrome, the genetics of oncocytosis is not known. Whether oncocytomas and oncocytosis are similar to BDH syndrome, in which the tumors diploid (as most oncocytomas are), or show chromosomal losses may be significant regarding the observation that in oncocytosis, there frequently is morphological evidence of progression to chromophobe carcinoma. Here we report on the case of a 69-year old male who underwent a staged procedure of partial nephrectomy on the left side and right radical nephrectomy for multiple renal tumors. The tumors were studied by routine hematoxylin and eosin morphology, immunohistochemistry, cytogenetics, and loss of heterozygosity analysis. Both kidneys had numerous oncocytic neoplasms morphologically progressing from oncocytomas to hybrid tumors with chromophobe carcinoma. Genetic studies demonstrated progression from normal cytogenetics to chromosomal losses similar to those in some oncocytomas and in chromophobe carcinomas. The genetics of this apparently nonfamilial oncocytoma differs from that of BDH syndrome and is characterized by losses involving chromosomes 1, 14, 21, and Y. To our knowledge, this is the first report of the genetic and cytogenetic findings in oncocytosis not related to BDH syndrome and may suggest a possible model of progression from oncocytoma to chromophobe renal cell carcinoma.     

Lack of genetic changes at specific genomic sites separates renal oncocytomas from renal cell carcinomas

Morphological similarities between renal oncocytomas and ‘oncocytic’ renal cell carcinomas (RCCs) make a differential diagnosis in many cases difficult. A series of 41 renal oncocytomas has been analysed by microsatellite markers from chromosomes 1, 2, 3p, 6q, 8p, 9, 10, 13q, 14q, 17, and 21, alterations of which are known to be involved specifically in non-papillary and chromophobe RCCs. Only eight of the 41 renal oncocytomas showed loss of heterozygosity (LOH). LOH at chromosomes 1 and 14 occurred in four tumours each and at chromosomes 2, 8, and 9 in one tumour each. Combined LOH at chromosomes 1, 9, and 14 and also at chromosomes 1 and 14 occurred in one case each. No LOH was seen at any other genomic sites. The lack of combination of LOH at specific chromosomal sites differentiates renal oncocytomas from other renal cell tumours with overlapping phenotypes. Applying the microsatellite assay described here, the diagnosis can be established within 2 days, from fresh as well as from paraffin-embedded material. © 1998 John Wiley & Sons, Ltd.