Genetic and epigenetic alterations during renal carcinogenesis

Renal cell carcinoma (RCC) is not a single entity, but comprises a group of tumors including clear cell RCC, papillary RCC and chromophobe RCC, which arise from the epithelium of renal tubules. The majority of clear cell RCCs, the major histological subtype, have genetic or epigenetic inactivation of the von Hippel-Lindau (VHL) gene. Germline mutations in the MET and fumarate hydratase (FH) genes lead to the development of type 1 and type 2 papillary RCCs, respectively, and such mutations of either the TSC1 or TSC2 gene increase the risk of RCC. Genome-wide copy number alteration analysis has suggested that loss of chromosome 3p and gain of chromosomes 5q and 7 may be copy number aberrations indispensable for the development of clear cell RCC. When chromosome 1p, 4, 9, 13q or 14q is also lost, more clinicopathologically aggressive clear cell RCC may develop. Since renal carcinogenesis is associated with neither chronic inflammation nor persistent viral infection, and hardly any histological change is evident in corresponding non-tumorous renal tissue from patients with renal tumors, precancerous conditions in the kidney have been rarely described. However, regional DNA hypermethylation on C-type CpG islands has already accumulated in such non-cancerous renal tissues, suggesting that, from the viewpoint of altered DNA methylation, the presence of precancerous conditions can be recognized even in the kidney. Genome-wide DNA methylation profiles in precancerous conditions are basically inherited by the corresponding clear cell RCCs developing in individual patients: DNA methylation alterations at the precancerous stage may further predispose renal tissue to epigenetic and genetic alterations, generate more malignant cancers, and even determine patient outcome. The list of tumor-related genes silenced by DNA hypermethylation has recently been increasing. Genetic and epigenetic profiling provides an optimal means of prognostication for patients with RCCs. Recently developed high-throughput technologies for genetic and epigenetic analyses will further accelerate the identification of key molecules for use in the prevention, diagnosis and therapy of RCCs.     

Recent classification of renal epithelial tumors

The recent classification of renal tumors is based on genetic evidence as well as on histologic features. Malignant tumor includes clear cell renal carcinoma (RCC), multilocular cystic RCC, papillary RCC, chromophobe RCC, carcinoma of the collecting duct of Bellini, renal carcinoma associated with Xp11.2 translocations/TFE3 gene fusions and mucinous tubular and spindle cell carcinoma. Benign tumor is subdivided into papillary adenoma, renal oncocytoma and metanephric adenoma. Recently, new disease entities such as acquired cystic disease-associated RCC, clear cell papillary RCC and renal carcinoma with t(6;11)(p21:q12) have been discovered. In this article, we briefly review and introduce the clinical, morphological and genetic features of these tumor entities.     

Tuberous sclerosis-associated renal cell carcinoma. Clinical, pathological, and genetic features.

The tuberous sclerosis complex (TSC) is a multisystem autosomal dominant disorder characterized by seizures, mental retardation, and hamartomas. Patients with TSC have been reported to develop renal cell carcinomas (RCC) with increased frequency, an observation that is supported by the Eker rat model. To address the role of the tuberous sclerosis tumor suppressor genes in the pathogenesis of RCC, we studied six TSC-associated RCCs. Our findings suggest that some TSC-associated RCCs have clinical, pathological, or genetic features distinguishing them from sporadic RCC. Clinically, the TSC-associated tumors occurred at a younger age (mean, 36 years) than sporadic tumors and occurred primarily in women. Four of the six patients died of metastatic disease. Pathologically, five tumors displayed clear cell morphology. Of those five, two had high-grade spindle cell areas and one had granular cell histology in addition to the clear cell areas. A sixth tumor was anaplastic throughout. Four of the six tumors immunostained positively for a melanocyte-associated marker, HMB-45. HMB-45 positivity has been seen in two other TSC lesions: renal angiomyolipomas and pulmonary lymphangiomyomatosis. Five tumors were analyzed for loss of heterozygosity. Two had loss of heterozygosity on chromosome 9q34 and one had loss of heterozygosity on chromosome 16p13. We conclude that TSC-associated RCCs occur at an earlier age than sporadic RCCs, that some TSC-associated renal carcinomas have a different immunophenotype than sporadic RCCs, and that the TSC tumor suppressor genes may play a specific pathogenic role in these tumors.     

Papillary renal cell carcinoma with clear cell cytomorphology and chromosomal loss of 3p

AIMS: Cytogenetic studies on renal cell carcinomas (RCCs) have disclosed a correlation between chromosome aberrations and histomorphological features. Nevertheless, it is still controversial whether the cytomorphology of the tumour cells (clear cell, chromophilic, chromophobe) or their growth pattern (nonpapillary, papillary) is more discriminative for the combined histomorphological-cytogenetic classification of RCCs. METHODS AND RESULTS: Three RCCs with papillary growth pattern and clear cell cytomorphology were analysed by classical cytogenetics using standard G-banding techniques. Each tumour displayed clonal aberrations leading to loss of terminal 3p chromosomal segments. Monosomy 14 was also consistently found. Trisomy 17 was not observed in any of the tumours. CONCLUSIONS: This series of three RCCs consisting of clear cells with papillary architecture revealed chromosomal aberrations characteristic for the conventional (clear cell) RCC. Irrespective of the predominant papillary growth pattern, none of the cases were characterized by trisomy of chromosomes 3q, 7, 8, 12, 16, 17 and 20 and loss of Y chromosome which are widely regarded as the most consistent genetic alterations for papillary RCC. Therefore, our cytogenetic findings provide evidence that papillary clear cell RCCs should be classified according to their cytomorphology rather than their growth pattern even when papillary architecture is prominent.     

青少年肾细胞癌的临床病理及分子遗传学研究

目的 探讨青少年肾细胞癌的临床病理特征、遗传学改变、鉴别诊断及预后.方法 对46例青少年肾细胞癌进行光镜观察及免疫组织化学染色,随访并复习相关文献.对46例肿瘤进行von Hippel-Lindau(VHL)基因区域杂合性缺失(LOH)及VHL基因突变筛查.结果 共诊断19例Xp11.2易位/TFE3基因融合相关性肾癌(Xp11 RCC)、9例透明细胞癌、17例乳头状肾细胞癌(PRCC)和1例不能分类肾细胞癌.19例Xp11 RCC均TFE3阳性,而TFEB阴性.8例肿瘤具有巢状和乳头状结构形态类似t(X;17)ASPL-TFE3型肾癌,6例肿瘤组织学类似t(X;1)PRCC-TFE3型肾癌,4例肿瘤形态像透明细胞癌,1例肿瘤组织学形态文献中未被检索到,表现为细胞核呈毛玻璃样,核仁不明显,可见核沟,肿瘤间质见大量黏液.LOH及VHL突变检测结果显示,仅1例透明细胞癌和1例2型PRCC存在LOH,并且该2型PRCC的VHL基因的一个剪切位点存在胚系突变,553+5 G→C.其余45例均未检测出VHL突变.统计学分析表明TFE3阳性肾细胞癌比TFE3阴性肾细胞癌更倾向于高病理分期(pT3/pT4),并且预后较差(P=0.035).结论 青少年肾细胞癌表现出不同的组织学形态以及分子遗传学背景.其中Xp11 RCC为最常见的肾癌亚型.TFE3阳性肾细胞癌的预后要差于TFE3阴性肾细胞癌.     

Chromosomal Imbalances in Papillary Renal Cell Carcinoma : Genetic Differences between Histological Subtypes

Papillary renal-cell carcinoma (RCC) is a renal carcinoma variant with distinct gross, microscopic, and cytogenetic features. Recently, a type 1 (pale cytoplasm, small-cell) and a type 2 (eosinophilic cytoplasm, large-cell) subtype of papillary RCC have been described. Chromosomal alterations associated with these tumor types were examined in 25 papillary RCCs by comparative genomic hybridization. Relative copy number gains were frequently detected at chromosomes 7p (56%), 7q (44%), 12q (28%), 16q (32%), 17p (56%), 17q (76%), and 20q (32%). Chromosomal regions that were most often lost included 1p (24%), 4q (36%), 6q (40%), 9p (36%), 13q (36%), Xp (28%), Xq (36%), and Y (73%). There were clinical and genetic differences between the subtypes of papillary RCC. Type 2 tumors were of higher nuclear grade (P = 0.0012) and higher stage (P = 0.01) and had a worse prognosis (P = 0.03) than type 1 tumors. The number of DNA gains per tumor, especially gains of 7p and 17p, was significantly higher in type 1 than in type 2 tumors (P < 0.01). These data suggest the existence of two distinct morphological and genetic subgroups of papillary RCC. Losses of chromosome Xp were associated with short patient survival (P < 0.01). Despite the small number of cases, this finding suggests that a gene on chromosome Xp may contribute to papillary RCC progression.     

New and emerging renal tumour entities

In this review, we discuss new and emerging renal cell carcinoma (RCC) entities, including anaplastic lymphoma kinase (ALK) RCC, oncocytic variant of chromophobe RCC, atrophic kidney-like renal tumour, biphasic alveolosquamoid RCC, tubulocystic RCC, thyroid-like follicular carcinoma of the kidney, succinate dehydrogenase-deficient RCC, Birt–Hogg–Dubé syndrome-associated renal tumour, hereditary leiomyomatosis/renal cell carcinoma associated RCC, tuberous sclerosis-associated RCC, PTEN hamartoma tumour syndrome, clear cell papillary RCC, acquired cystic disease-associated RCC, Xp11.2 RCC, t(6;11) RCC and renal hemangioblastoma. These tumours have clinical, pathological and genetic features distinct from other common RCCs and therefore are important to recognize. Some of them have been recognized as distinct histological subtypes in the 2016 World Health Organization Classification. However, further studies are needed to elucidate their clinicopathologic features and molecular mechanisms.     

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.     

Renal cell carcinoma with leiomyomatous stroma—further immunohistochemical and molecular genetic characteristics of unusual entity

Renal cell carcinoma (RCC) with leiomyomatous stroma (RCCLS) is a recently recognized entity with indolent biological behavior. The diagnostic implication of absence/presence of VHL gene mutation, VHL hypermethylation, or/and loss of heterozygosity of chromosome 3p (LOH 3p) is widely discussed. Criteria for establishing a diagnosis of RCCLS are still lacking. Fifteen RCCLSs were retrieved from our registry. The cases were studied with consideration to the morphology, immunohistochemistry, and molecular genetics. All cases were composed of low-grade epithelial cells with clear cytoplasm arranged in nests intermingled with abundant leiomyomatous stroma. Age range of the patients was 33 to 78 years. The tumor size ranged from 1.5 to 11 cm. Six of the patients were males, and 9, females. Of the 15 tumors sent for molecular genetic testing, only 12 cases were analyzable. All cases were analyzable immunohistochemically. Of 12 of these cases, 5 showed complete absence of VHL gene mutation, VHL hypermethylation, and LOH 3p. Of these 5 cases, 3 were positive for cytokeratin 7 (CK 7). All of the 5 cases were positive for carbonic anhydrase 9, vimentin, and CD10. The remaining 7 of 12 genetically analyzable cases were found to have had VHL hypermethylation, LOH 3p, VHL gene mutation, or a combination of the former 2 characteristics. These 7 cases were positive for vimentin. Variable reactivity was found for CK 7, carbonic anhydrase 9, α-methylacyl-CoA racemase, and CD10. In 1 of these 7 cases, gains on chromosomes 7 and 17 as well as hypermethylation of VHL gene were found. This case was considered as clear cell RCC with aberrant status of chromosomes 7 and 17. Conclusions: (1) Leiomyomatous stroma is not specific for the so called RCCLS. It can be seen also in otherwise typical clear cell RCCs. (2) There are no characteristic morphological/immunohistochemical features unique for “RCCLS.” (3) Our results indicate that only tumors with the absence of the VHL gene mutation, hypermethylation, and LOH 3p can be diagnosed as RCCLS. (4) Relation of RCCs with a prominent smooth muscle stroma to the renal angiomyoadenomatous tumor/clear cell papillary (tubopapillary) RCC is not clearly evident from our study and has to be further analyzed on larger cohort of the patients.     

The expression of heterochromatin protein 1α/β in the kidney tumors: a microarray immunohistochemical study

Kidney tumors of various types may behave differently and have different prognosis. Due to some overlapping morphological features and immunohistochemical staining pattern, they may pose diagnostic challenge. Therefore, it is necessary to explore additional immunohistochemical stains to help in subclassifying these epithelial neoplasms. Tissue microarrays of 20 cases each of renal cell carcinomas (RCC) of clear cell, chromophobe, and papillary variants and oncocytoma were constructed and used to test the heterochromatin-associated protein (HP) 1α/β expression. HP-1α/β showed strong nuclear staining. Expression of HP-1α/β was found mostly in papillary RCC (79%) and oncocytoma (75%) but less in chromophobe (30%) and clear cell RCCs (35%). HP-1α/β may be useful in the differential diagnosis of renal tumors, especially in the differentiation of chromophobe RCC and oncocytoma.     

Renal cell carcinoma in South Korea: a multicenter study

The incidence of renal cell carcinoma (RCC) in South Korea is steadily becoming similar to that in Western countries. This study summarizes the results of a 3-year multicenter survey of RCC in South Korea, conducted by the Korean Genitourinary Pathology Study Group. A total of 795 cases of RCC were collected from 20 institutes between 1995 and 1997, including 686 clear cell RCCs (86.3%), 58 papillary RCCS (7.30%), 49 chromphobe RCCs (6.16%), and 2 collecting duct RCCs (0.25%). At least 5 years of follow-up was available for 627 clear cell, 54 papillary, and 49 chromophobe RCCs. All subtypes presented most frequently with stage T3aN0M0 at the time of operation, and papillary RCCs demonstrated more frequent lymph node metastasis. Overall survival was not significantly related to the histological subtype (clear cell vs papillary, P = 0.8651; clear cell vs chromophobe, P = 0.0584; papillary vs chromophobe, P = 0.0743). For clear cell RCCs, statistically significant associations were found between overall survival and sex (P = 0.0153), multiplicity (P = 0.0461), necrosis (P = 0.0191), age, sarcomatoid change, TNM stage, nuclear grade, and modality of treatment (all P <0.0001). Overall survival was significantly associated with tumor size (P = 0.0307), nuclear grade (P = 0.0235), multiplicity, sarcomatoid change, and TNM stage (all P <0.0001) for papillary RCCs and with the presence of sarcomatoid change (P = 0.0281), nuclear grade (P = 0.0015), treatment modality (P = 0.0328), and TNM stage (P <0.0001) for chromophobe RCCs. Age (P = 0.0125), nodal stage (P = 0.0010), and treatment modality (P = 0.0001) were significant independent prognostic indicators for clear cell RCC on multivariate analysis. This is the first multicenter study of RCC in South Korea, demonstrating the general patterns and prognostic factors of Korean RCCs.     

Imprinted DLK1 is a putative tumor suppressor gene and inactivated by epimutation at the region upstream of GTL2 in human renal cell carcinoma

A common deletion at chromosomal arm 14q32 in human renal cell carcinoma (RCC) prompted us to explore a tumor suppressor gene (TSG) in this region. We report that imprinted DLK1 at 14q32, a regulator of adipocyte differentiation, is a candidate TSG in RCCs. DLK1 expression was lost in 39 out of 50 (78%) primary RCC tissues, whereas expression of DLK1 was maintained in every normal kidney tissue examined. DLK1 was expressed in only one of 15 (7%) RCC-derived cell lines. In order to see the biological significance of DLK1 inactivation in RCCs, we tested the effect of restoration of DLK1 in RCC cell lines, using a recombinant retrovirus containing the gene. Reintroduction of DLK1 into DLK1-null RCC cell lines markedly increased anchorage-independent cell death, anoikis and suppressed tumor growth in nude mice. We then investigated the underlying mechanisms for DLK1 inactivation in RCCs. We found loss of heterozygosity at this region in 12 out of 50 RCC tissues (24%). To explore the role of epigenetic regulation of DLK1 inactivation in RCCs, we conducted methylation analysis of the upstream region and the gene body of DLK1. We could not find a differentially methylated region in either the upstream region or the gene body of DLK1. However, we found that gain of methylation upstream of GTL2, a reciprocal imprinted gene for DLK1, is a critical epigenetic alteration for the inactivation of DLK1 in RCCs. The present data have shown that gain of methylation upstream of the untranslated GTL2 leads to pathological downregulation of DLK1 in RCCs.     

Analysis of the Birt-Hogg-Dubé (BHD) tumour suppressor gene in sporadic renal cell carcinoma and colorectal cancer

Germline mutations in the BHD gene cause the dominantly inherited cancer susceptibility disorder, Birt-Hogg-Dubé (BHD) syndrome. Individuals with BHD are reported to have an increased risk of renal cell carcinoma (RCC) and of colorectal polyps and cancer. The BHD gene maps to 17p11.2, and to investigate whether somatic inactivation of the BHD gene region is implicated in the pathogenesis of sporadic RCC and colorectal cancer (CRC), we performed mutation analysis in 30 RCC primary tumours and cell lines, and 35 CRCs and cell lines. A somatic missense mutation (Ala444Ser) with loss of the wild type allele (consistent with a two hit mechanism of tumorigenesis) was detected in a primary clear cell RCC, and a further missense mutation (Ala238Val) was identified in a clear cell RCC cell line for which matched normal DNA was not available. A somatic missense substitution (Arg392Gly) was identified in a primary CRC, and the same change was detected in three RCCs (all oncocytomas) for which matched normal DNA was not available. A germline Arg320Gln missense variant detected in a primary CRC was not detected in 40 control individuals or in a further 159 familial and sporadic CRC cases. However, AA homozygotes for an intronic single nucleotide polymorphism (c.1517+6 G-->A) were under-represented in familial cases compared with controls (p = 0.03). For some tumour suppressor genes, epigenetic silencing is a more common mechanism of inactivation than somatic mutations. However, we did not detect evidence of epigenetic silencing of BHD in 19 CRC and RCC cell lines, and BHD promoter region hypermethylation was not detected in 20 primary RCCs. These findings suggest that BHD inactivation occurs in a subset of clear cell RCC and CRC.     

The diagnostic utility of MOC31, BerEP4, RCC marker and CD10 in the classification of renal cell carcinoma and renal oncocytoma: an immunohistochemical analysis of 328 cases

AIMS: To demonstrate the diagnostic utility of MOC31, BerEP4, renal cell carcinoma marker (RCC Ma) and CD10 in the classification of RCC and renal oncocytoma, based upon a comprehensive immunohistochemical analysis. METHODS AND RESULTS: Immunohistochemistry was performed on 328 samples consisting of 256 clear cell/conventional, 27 papillary, 28 chromophobe, five collecting duct, five unclassified RCCs and seven renal oncocytomas using antibodies MOC31, BerEP4 and antibodies against cytokeratins (KL-1, CAM5.2, 34betaE12, cytokeratin 7), RCC Ma, epithelial membrane antigen, E-cadherin, CD10, CD15 and vimentin. Multivariate analysis showed that MOC31, BerEP4, RCC Ma and CD10 have discriminatory value. MOC31 and BerEP4 chiefly labelled distal tubules of normal kidney while RCC Ma and CD10 labelled the proximal tubules. Twenty-three chromophobe RCCs (82%) were reactive for MOC31, while only four clear cell RCCs and three papillary RCCs were positive for this marker. Clear cell RCCs were characterized by a high positive rate for CD10 (82%) and a low positive rate for BerEP4 (27%). Papillary RCCs frequently coexpressed RCC Ma and BerEP4 (51%). All renal oncocytomas were negative for MOC31 and CD10. CONCLUSIONS: MOC31 has diagnostic merit in discerning chromophobe RCC. The CD10+/BerEP4- profile and RCC Ma+/BerEP4+ profile achieve moderate sensitivity and good specificity for clear cell RCC and papillary RCC, respectively. The non-reactivity for both MOC31 and CD10 is helpful in distinguishing renal oncocytoma from RCC. When properly selected, antibodies have immunohistochemical diagnostic utility for the classification of renal cortical epithelial tumours.     

Overexpression of c-met proto-oncogene associated with chromophilic renal cell carcinoma with papillary growth

 Various genetic changes are involved in human renal cell carcinomas (RCCs). However, the molecular events related to other cytomorphological subtypes of RCC are not well known, apart from the relationship between the von Hippel-Lindau tumour suppressor gene and clear cell subtype RCC. We examined the overexpression of several growth factor receptors immunohistochemically and analyzed their relationship to the cytomorphological characters in 120 cases of RCCs. These receptors included c-met proto-oncogene product (c-MET), epidermal growth factor receptor (EGFR) and transforming growth factor beta receptor II (TGFβR). The overexpression of c-MET was detected in all cases (20/20) of the tubulo-papillary growth type and 78.3% (18/23) of chromophilic cell subtype, resulting in a very significant associations between c-MET overexpression and tubulo-papillary growth RCCs (P<0.0001), c-MET and chromophilic subtype RCCs (P<0.0001), and c-MET and EGFR (P<0.0001). EGFR overexpression was significantly associated with the compact growth RCCs (49/89, P<0.0001), clear cell subtype RCCs (P<0.005) and the overexpression of TGFβR (P<0.0001). These results strongly suggest a close correlation between the overexpression of c-MET and development of the chromophilic subtype of RCC with papillary growth pattern. EGFR expression is closely related to the pathogenesis of the clear cell subtype of RCC with compact growth pattern. The overexpression of c-MET, EGFR, and TGFβR may have roles that are individually significant in the morphogenesis of RCC. Received: 20 January 1998 / Accepted: 22 July 1998     

Renal cell carcinoma marker reliably discriminates central nervous system haemangioblastoma from brain metastases of renal cell carcinoma

Aims:  The distinction between central nervous system (CNS) metastases of clear cell renal cell carcinoma (RCC) and CNS haemangioblastoma still poses a challenge to the pathologist. Since both entities occur in von Hippel–Lindau disease, this aggravates the issue. The antibody renal cell carcinoma marker (RCC-ma) has been suggested to identify primary RCCs specifically, but its value for diagnosing metastases of RCC is controversial. The aim was to assess two distinct clones of the RCC-ma for their potential to: (i) identify primary RCCs and (ii) differentiate between CNS metastases of clear cell RCC and CNS haemangioblastomas.
Methods and results:  Using tissue microarrays, 77% ( n  = 363; PN-15) and 66% ( n  = 355; 66.4C2) of clear cell RCCs, and 93% (PN-15) and 74% (66.4C2) of papillary RCCs ( n  = 46) were immunopositive for RCC-ma, whereas none of the investigated chromophobe RCCs ( n  = 22) or any of the oncocytomas ( n  = 15) showed immunoreactivity. Importantly, 50.9% of CNS metastases of clear cell RCCs ( n  = 55) exhibited RCC-ma expression, whereas all CNS haemangioblastomas (71) were negative.
Conclusions:  Both RCC-ma clones, despite some variation in their sensitivity to detect clear cell and papillary RCCs, are of value in differentiating subtypes of primary RCC and are excellent markers for discriminating clear cell lesions in the brain.     

Immunoexpression of SDHB,FH, and CK20 among eosinophilic renal tumors: A tissue microarray study

BackgroundDifferential diagnosis can be a challenge for eosinophilic subtypes of renal cell tumors due to their overlapping histomorphological and immunohistochemical features. We aimed to investigate the frequency of rare variants of renal cell carcinomas (RCCs) such as succinate dehydrogenase-deficient RCC (SDDRCC), hereditary leiomyomatosis and RCC (HLRCC)-associated RCC, and eosinophilic, solid, and cystic RCC (ESCRCC) in our population.Materials and methodsRenal tumors which could be considered in the eosinophilic tumor category were included: 91 conventional clear cell RCCs with eosinophilic cytoplasm, 72 papillary RCCs, 74 chromophobe RCCs, 88 oncocytomas, and 37 other rare subtypes. Using the tissue microarray method, succinate dehydrogenase B (SDHB), fumarate hydratase (FH), and cytokeratin 20 (CK20) antibodies were performed by immunohistochemistry. Immunohistochemistry was repeated on whole block sections for selected cases. The utility of these antibodies in the differential diagnosis was also investigated.ResultsLoss of SDHB expression was detected in three tumors, two of which showed typical morphology for SDDRCC. In additional two tumors, SDHB showed weak cytoplasmic expression without a mitochondrial pattern (possible-SDHB deficient). None of the tumors showed loss of FH expression. Heterogeneous reactions were observed with SDHB and FH antibodies. Only one ESCRCC was detected with diffuse CK20 positivity.ConclusionSDDRCCs, HLRCC-associated RCCs, and ESCRCCs are very rare tumors depending on the population. Possible weak staining and focal loss of SDHB and FH expression should be kept in mind and genetic testing must be included for equivocal results.     

Chromosomal abnormalities in renal cell carcinoma variants detected by Urovysion fluorescence in situ hybridization on paraffin-embedded tissue

Urovysion fluorescence in situ hybridization (UVFISH) identifies malignant cells in urine by detecting specific urothelial carcinoma-related chromosomal abnormalities. Some renal carcinomas (RCCs) share overlapping chromosomal aberrations with urothelial carcinoma. Malignant renal cells that are shed in urine can potentially cause a positive UVFISH result. We evaluated UVFISH in RCCs to determine its potential applicability to the diagnosis and grading of RCCs. Paraffin blocks from 39 RCCs (25 clear cell, 9 papillary, 2 chromophobe, and 3 sarcomatoid) and 15 controls (5 renal oncocytomas and 10 urothelial carcinomas) were tested. Of the RCCs, 15 (40%) were UVFISH-positive (9/25 [40%] clear cell, 3/9 [30%] papillary, 1/2 [50%] chromophobe, and 2/3 [67%] sarcomatoid carcinoma) and 24 (60%) were negative. Of the 15 controls, 8 (～50%) were UVFISH-positive (2/5 [40%] oncocytomas and 6/10 [60%] urothelial carcinomas) and 7 (～50%) were UVFISH-negative. Polysomy of chromosome 17 showed a statistically significant correlation with RCC subtype, being absent in most of the clear cell RCCs (P = .0096) compared with other RCCs. Polysomy of chromosome 7 was more frequent in high-grade than low-grade RCC (P = .0197) and more likely in high-grade clear cell than low-grade clear cell RCC (P = .0120). In conclusion, we showed that RCC has overlapping chromosomal abnormalities with urothelial carcinoma and can cause a positive UVFISH result. This has implications for the interpretation of Urovysion in patients whose urine contains malignant cells but who have negative cystoscopy and a concomitant renal mass. The chromosomal abnormalities observed in RCC are not distinct from those in urothelial carcinoma; therefore, UVFISH cannot distinguish these tumor types, nor can it type or grade RCC.     

Array comparative genomic hybridization identifies a distinct DNA copy number profile in renal cell cancer associated with hereditary leiomyomatosis and renal cell cancer

Hereditary leiomyomatosis and renal cell cancer (HLRCC) is a tumor predisposition syndrome with cutaneous and uterine leiomyomatosis as well as renal cell cancer (RCC) as its clinical manifestations. HLRCC is caused by heterozygous germline mutations in the fumarate hydratase (fumarase) gene. In this study, we used array comparative genomic hybridization to identify the specific copy number changes characterizing the HLRCC‐associated RCCs. The study material comprised formalin‐fixed paraffin‐embedded renal tumors obtained from Finnish patients with HLRCC. All 11 investigated tumors displayed the papillary type 2 histopathology typical for HLRCC renal tumors. The most frequent copy number changes detected in at least 3/11 (27%) of the tumors were gains in chromosomes 2, 7, and 17, and losses in 13q12.3‐q21.1, 14, 18, and X. These findings provide genetic evidence for a distinct copy number profile in HLRCC renal tumors compared with sporadic RCC tumors of the same histopathological subtype, and delineate chromosomal regions that associate with this very aggressive form of RCC. © 2009 Wiley‐Liss, Inc.