LMP2, a novel immunohistochemical marker to distinguish renal oncocytoma from the eosinophilic variant of chromophobe renal cell carcinoma

LMP2 is a subunit of the immunoproteasome that is overexpressed in oncocytic lesions of the thyroid gland. This study was designed to assess the expression profile and diagnostic utility of LMP2 in two renal oncocytic tumors that share similar morphologic features but have different clinical outcomes: renal oncocytoma (RO) and the eosinophilic variant of chromophobe renal cell carcinoma (CHRCC-EO). A total of 56 RO, 38 classic CHRCC, and 7 CHRCC-EO cases, as well 84 normal kidney controls, were selected from the Johns Hopkins surgical pathology archive and stained for LMP2 using a standard immunohistochemical protocol. Sections were scored for cellular location (nuclear versus cytosolic), intensity (from 0 to 3), and percent of area involved (from 0 to 100%), and an H score was calculated multiplying the intensity by the extent of the staining signal. The cytoplasmic expression of LMP2 was similar among the renal lesions, being present in 44 of 56 (79%) ROs, 27 of 38 (71%) CHRCCs, and 7 of 7 (100%) CHRCC-EO cases. The nuclear expression of LMP2, however, was more informative. All CHRCC-EO cases (7 of 7, 100%) strongly showed nuclear LMP2 staining, as opposed to only 2 of 56 (4%, P < 0.0001) ROs and 9 of 38 (24%, P = 0.0001) classic CHRCCs. These results suggest that the nuclear LMP2 expression can be used in clinical scenarios where histological distinction between RO and CHRCC-EO remains challenging.     

Fractal dimension of microvasculature in renal oncocytomas and chromophobe renal cell carcinomas

The aim of this study was to evaluate and compare the microvascular architectural complexity in oncocytomas and chromophobe renal cell carcinomas (ChRCCs) by fractal box-counting on CD34-labeled slides.     

Claudin-7 is highly expressed in chromophobe renal cell carcinoma and renal oncocytoma

Claudin-7 has recently been suggested to be a distal nephron marker. We tested the possibility that expression of claudin-7 could be used as a marker of renal tumors originating from the distal nephron. We examined the immunohistochemical expression of claudin-7 and parvalbumin in 239 renal tumors, including 179 clear cell renal cell carcinoma (RCC)s, 29 papillary RCCs, 20 chromophobe RCCs, and 11 renal oncocytomas. In addition, the methylation specific-PCR (MSP) of claudin-7 was performed. Claudin-7 and parvalbumin immunostains were positive in 3.4%, 7.8% of clear cell RCCs, 34.5%, 31.0% of papillary RCCs, 95.0%, 80.0% of chromophobe RCCs, and 72.7%, 81.8% of renal oncocytomas, respectively. The sensitivity and specificity of claudin-7 in diagnosing chromophobe RCC among subtypes of RCC were 95.0% and 92.3%. Those of parvalbumin were 80.0% and 88.9%. The expression pattern of claudin-7 was mostly diffuse in chromophobe RCC and was either focal or diffuse in oncocytoma. All of the cases examined in the MSP revealed the presence of unmethylated promoter of claudin-7 without regard to claudin-7 immunoreactivity. Hypermethylation of the promoter might not be the underlying mechanism for loss of its expression in RCC. Claudin-7 can be used as a useful diagnostic marker in diagnosing chromophobe RCC and oncocytoma.     

C-kit expression in renal oncocytomas and chromophobe renal cell carcinomas

C- kit encodes the membrane-bound tyrosine kinase KIT, whose expression has been identified in several types of human neoplasms. Recently, KIT has been reported to be a marker for chromophobe renal cell carcinoma (RCC) and renal angiomyolipoma. However, expression of this molecule has not been adequately studied in other renal tumors, particularly oncocytoma, which may morphologically resemble chromophobe RCC. In this study, we analyzed c- kit messenger RNA (mRNA) levels in 17 chromophobe RCCs and 20 renal oncocytomas obtained from complementary DNA (cDNA) microarrays. Furthermore, comprehensive immunohistochemical analysis of KIT protein using a monoclonal antibody was performed in 226 renal tumors including chromophobe RCC (n=40), oncocytoma (n=41), clear-cell RCC (n=40), renal angiomyolipoma (n=29), and papillary RCC (n=21) on tissue microarrays (TMAs) and was compared with immunostaining results from 25 chromophobe RCCs and 30 oncocytomas using standard sections. The staining intensity was semiquantitatively graded on a 3-tier scoring system. All chromophobe RCCs and oncocytomas showed significant overexpression of c- kit mRNA. The average increase of mRNA compared with normal kidney tissue was 7.4-fold for chromophobe RCCs and 7.4-fold for oncocytomas. Immunohistochemical expression of KIT was found in most chromophobe RCCs (95% in TMAs and 96% in conventional sections) and oncocytomas (88% in TMAs and 100% in conventional sections) but was infrequently observed in renal angiomyolipomas (17%), papillary RCCs (5%), and clear-cell RCCs (3%). Furthermore, the average KIT immunoreactivity in TMAs was stronger in chromophobe RCC (1.93) and oncocytoma (2.07) than in other subtypes of renal tumors tested, including angiomyolipomas (0.17), papillary RCCs (0.05), and clear-cell RCCs (0.03). In conclusion, we found a significant elevation of c- kit mRNA by cDNA expression microarrays and overexpression of KIT protein by immunohistochemistry not only in chromophobe RCCs but also in oncocytomas. In contrast, immunohistochemical expression of KIT was not detected in most other types of renal cell tumors evaluated. The differential expression of c- kit in these renal tumors may have diagnostic and therapeutic implications.     

Pigmented microcystic chromophobe renal cell carcinoma

We report a case of a 60-year-old female with a pigmented microcystic chromophobe renal cell carcinoma (PMCRCC). The tumor was 4.5cm in diameter, and was located in the right kidney. Grossly, on cross section, the tumor was light gray with multiple small brown to black pigmented foci up to 0.2cm in diameter. Histologically, the tumor showed a microcystic arrangement with cribriform areas and formation of adenomatous structures. The microcystic and cribriform areas were composed of larger pale cells and smaller eosinophilic cells, with cytological features of conventional chromophobe renal cell carcinoma (CRCC). The cytological features of the cells within the adenomatous structures were different. These cells were mostly columnar with nuclei at the base, and had a variable amount of pale to eosinophilic cytoplasm. There were foci of ample brown pigmentation located in the cytoplasm of the tumor cells and extracellularly. In addition, microscopic calcifications were present. Immunohistochemically, the tumor cells were positive for EMA, E-cadherin, cytokeratin CAM5.2, and cytokeratin AE1/AE3. Cytokeratin 7 was positive only focally. S-100 protein, melan A, HMB 45, vimentin, and CD117 were negative. PMCRCC is a rare tumor. To the best of our knowledge, only one series containing 20 cases of this variant of CRCC has been described to date. The important feature is that PMCRCC seems to have a relatively benign biological behavior, and distant metastases and sarcomatoid transformation are absent.     

Progesterone receptor reactivity in renal oncocytoma and chromophobe renal cell carcinoma

Aims:  To investigate the reactivity for oestrogen and progesterone receptors (ER and PR) in renal oncocytoma (RO) and chromophobe renal cell carcinoma (CHRCC).
Materials and methods:  Thirty-eight RO, 25 CHRCC, 20 papillary RCC with oncocytic cytoplasm and 10 clear cell RCC with dominant eosinophilic cytoplasm were submitted for immunohistochemistry for ER, PR, CD117 and RCC.
Results:  All cases of RO and CHRCC displayed moderately positive reactivity for PR. The nuclear reactivity ranged from 60% to 90% in RO and from occasional cells to 70% in CHRCC. In CHRCC, reactivity tended to be more prevalent in areas of tumour cells with eosinophilic cytoplasm. Progesterone reactivity was focal in areas. All RO and most CHRCC were reactive for CD117 and neither RO nor CHRCC was reactive for RCC. CD117 reactivity tended to be more intense in CHRCC than in RO. Negative reactivity for CD117 and positive reactivity for RCC were observed in almost all RCC, as reported in the literature.
Conclusions:  PR can be used in combination with CD117 and RCC in the differential diagnosis of RO and eosinophilic variant of CHRCC with other RCC with oncocytic or eosinophilic cytoplasm.     

Cytokeratin 7: a useful adjunct in the diagnosis of chromophobe renal cell carcinoma

AIMS: The histopathological diagnosis of chromophobe renal cell carcinoma can present a diagnostic challenge, as these tumours can resemble either conventional renal cell carcinoma or oncocytoma. The aim of this study was to determine whether cytokeratin 7 expression is of practical use in the distinction of these three entities. METHODS AND RESULTS: A total of 40 cases previously diagnosed as either chromophobe renal cell carcinoma, conventional renal cell carcinoma or oncocytoma were identified. A representative section of each was stained with H&E and cytokeratin 7. Following independent review of the cases by three pathologists, a consensus diagnosis for each case was reached and the pattern of cytokeratin 7 staining was assessed. There were 12 cases of chromophobe renal cell carcinoma in the study, all of which showed a characteristic peripheral membrane pattern of staining for cytokeratin 7. Seventeen of the 18 cases of conventional renal cell carcinoma studied were negative for cytokeratin 7, while one case showed weak focal staining of <5% of the cells. The 10 cases of oncocytoma showed patchy weak to moderate cytoplasmic expression of cytokeratin 7, without the characteristic peripheral membrane accentuation seen in the chromophobe carcinomas. CONCLUSIONS: Immunohistochemical staining for cytokeratin 7 appears to be a useful adjunct in the diagnosis of chromophobe renal cell carcinoma, and in distinguishing this tumour from both oncocytoma and conventional renal cell carcinoma.     

Nucleophosmin expression in renal cell carcinoma and oncocytoma

The objective of this study was to investigate nucleophosmin/B23 (NPM) expression in renal cell carcinomas (RCC) and renal oncocytomas. The expression of NPM was studied by immunohistochemical methods on 59 RCCs, 9 oncocytomas, and 19 tumour-negative renal tissues. The expression was assessed relative to various clinicopathological variables and histological subtypes, to determine its potential role as a prognostic and diagnostic marker. All tumours showed nuclear staining, and a minority also exhibited cytoplasmic immunoreactivity. Two patterns of nuclear staining were observed: nuclear staining with a prominent nucleolus (nucleolar staining) and nuclear staining without a prominent nucleolus. There were significant differences, in both nuclear staining and cytoplasmic NPM expression, between oncocytomas and chromophobe RCCs (p < 0.001) and clear cell RCCs (p < 0.001). Cytoplasmic NPM expression was markedly lower in RCCs than in oncocytomas. A statistically significant correlation was discovered between nucleolar staining and nuclear grade (p < 0.001, r = 0.5). No relationship was found between cytoplasmic expression of NPM and any of the clinicopathological parameters or survival. NPM might be a useful immunohistochemical marker for differential diagnosis between oncocytoma and chromophobe RCC. In addition, increased nucleolar NPM expression in RCCs appears to be associated with tumour progression.     

嫌色性肾细胞癌和肾嗜酸细胞腺瘤中CK7、Claudin-7、Epcam、vimentin的表达及其临床意义

目的探讨CK7、Claudin-7、上皮细胞黏附分子(Epcam)和vimentin在嫌色性肾细胞癌(chromophobe renal cell carcinoma,Ch RCC)和肾嗜酸细胞腺瘤(renal oncocytoma,RO)中的表达,及其诊断与鉴别诊断的意义。方法采用免疫组化En Vision两步法检测24例Ch RCC和17例RO中CK7、Claudin-7、Epcam和vimentin的表达。结果 CK7、Claudin-7、Epcam和vimentin在Ch RCC中的阳性率分别为79.17%(19/24)、95.83%(23/24)、91.67%(22/24)、8.33%(2/24),在RO中的阳性率分别为23.53%(4/17)、41.18%(7/17)、29.41%(5/17)、0(0/17);CK7、Claudin-7和Epcam在这两种肿瘤中的表达差异有统计学意义(P0.05);虽然vimentin在两种肿瘤中的表达差异无统计学意义(P0.05),但与其它含有嗜酸性细胞的肾脏肿瘤表达差异有显著性。结论 CK7、Claudin-7和Epcam可作为鉴别Ch RCC与RO的免疫标志物,vimentin有助于Ch RCC、RO与其它含有嗜酸性细胞的肾脏肿瘤鉴别。     

A renal cell carcinoma with components of both chromophobe and papillary carcinoma

We report a case of a morphologically unusual renal cell carcinoma with features of both chromophobe and papillary carcinoma. Immunohistochemical analysis of high molecular weight cytokeratins (HMWCK), cytokeratin 7 (CK7), cytokeratin 19 (CK19), c-Kit, and α-methylacyl-CoA racemase (AMACR) demonstrated differential profiles for the two components of the tumor, consistent with the respective patterns commonly observed for pure chromophobe and papillary renal cell carcinomas. Specifically, the chromophobe tumor cells expressed CK7 and c-Kit weakly, while HMWCK, CK19, and AMACR were not detectable. In contrast, the papillary tumor cells expressed uniformly HMWCK, CK7, and c-Kit and focally CK19 and AMACR. Fluorescence in situ hybridization analysis of nuclei isolated from paraffin-embedded tumor tissue detected monosomy 1, disomy 7, and monosomy 17, a common and characteristic finding in chromophobe carcinomas, in a majority of, but not all tumor cells, whereas a population characterized by disomy 1, trisomy 7, and trisomy 17, a frequent finding in papillary carcinoma, was not identifiable. Electron microscopic analysis revealed numerous characteristic small cytoplasmic vesicles in the chromophobe areas, which were absent in the papillary component. This case illustrates the rare coexistence of two distinct and admixed histologic types of renal cell carcinoma.     

Expression of secretagogin in clear-cell renal cell carcinomas is associated with a high metastasis rate

Renal cell carcinomas are divided into several subgroups according to their histopathologic characteristics. The outcome, therapy responses, and the applicability of molecular-targeted therapies depend on the tumor classification and on the tumor stage. Recent advances within the biomarker research facilitated the exact classification of the molecular character of the renal tumor. For example, the calcium-binding proteins parvalbumin and S-100A1 are characteristically expressed in renal cell carcinoma subgroups. This led us to investigate the expression of the novel calcium-binding protein secretagogin in renal cell carcinomas. Tissue microarray cylinders including 94 clear-cell renal cell carcinomas, 61 non-clear-cell renal cell carcinomas (37 papillary renal cell and 24 chromophobe carcinomas), and 30 oncocytomas were analyzed by immunohistochemistry. This showed remarkable secretagogin expression in 37% of the clear-cell renal cell carcinomas. Non-clear-cell renal cell carcinomas and oncocytomas were completely negative. Consequently performed immunoblotting analyses confirmed this expression profile. Because publicly available data direct toward a formation of a hierarchical cluster of secretagogin overexpressing clear-cell renal cell carcinomas, we conducted a clinical follow-up of the patients with clear-cell renal cell carcinoma. This revealed significantly more metastasis within the secretagogin-positive clear-cell renal cell carcinoma subgroup (49% versus 28%; P < .05). In conclusion, we report on detection of the novel calcium-binding protein secretagogin within a subgroup of clear-cell renal cell carcinomas. The increased metastasis rates within the secretagogin-positive subgroup of clear-cell renal cell carcinomas direct toward a clinical impact of our findings.     

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.     

Mitochondrial and chromosomal DNA alterations in human chromophobe renal cell carcinomas.

Renal cell tumours are characterized by the loss of chromosome 3p and trisomy of 5q segments (common, non-papillary renal cell carcinoma), or by trisomy of chromosomes 7 and 17 and loss of the Y chromosome (papillary renal cell carcinoma), or by random karyotype changes and mitochondrial DNA alterations (renal oncocytoma). We have studied by means of RFLP analysis the genomic and mitochondrial DNA in 11 chromophobe renal cell carcinomas, which have a unique morphology among kidney cancers. We found a loss of the constitutional heterozygosity at chromosomal regions 3p, 5q, 17p, and 17q, a combination of allelic losses that has not been found in other types of renal cell tumours. Three of the tumours showed a gross alteration in the restriction pattern of the mitochondrial DNA. A combined morphological and genetic analysis suggests that chromophobe renal cell carcinoma is a distinct entity.     

Expression of Opa interacting protein 5 (OIP5) is associated with tumor stage and prognosis of clear cell renal cell carcinoma

Opa interacting protein 5 (OIP5), overexpressed in some types of human cancers, has been reported to be associated with the carcinogenesis of human cancer. However, the biological function and clinical significance of OIP5 in human Clear Cell Renal Cell Carcinoma (CCRCC) remains unknown. In the present study, we found the expression of OIP5 was markedly upregulated in surgical CCRCC specimens and CCRCC cell lines. Immunohistochemical analysis revealed that paraffin-embedded archival CCRCC specimens exhibited higher levels of OIP5 expression than normal renal tissues. Further statistical analysis suggested the upregulation of OIP5 was positively correlated with the Fuhrman grade (P = 0.02), T classification (P = 0.015), N classification (P = 0.018) and clinical stage (P = 0.035). Also, patients with high OIP5 expression dramatically exhibited shorter survival time (P = 0.001). In addition, the OIP5 expression was an independent prognostic marker of overall survival of CCRCC patients in a multivariate analysis (P = 0.008). Experimentally, we demonstrated that silencing OIP5 in CCRCC cell lines by specific siRNA clearly inhibited cell growth. In conclusion, our findings suggested that OIP5 could be a valuable marker of CCRCC progression and prognosis, and a promising therapeutic target for CCRCC.     

Chromophobe renal cell carcinoma with osseous metaplasia containing fatty bone marrow element: a case report

A 27-year-old woman presenting with epigastric pain and dyspepsia was found to have a calcified mass in the upper-middle right kidney. Gross examination of the nephrectomy specimen revealed a 6.5 x 5 x 4 cm renal tumor with dense calcification and ossification. Histopathological examination of the tumor showed solid, trabecular sheets and nesting of polygonal epithelial cells with abundant cytoplasm and prominent cell border and mature bony tissue enclosing fatty marrow. Renal cell carcinoma is frequently associated with calcification, but ossification is extremely rare. To our knowledge, we report the fourth case of a chromophobe renal cell carcinoma with extensive calcification and ossification.