Variants and Variations in Epithelial Renal Cell Tumors in Adults: The Pathologist's Point of View

Context and ObjectivesThe Vancouver consensus conference of the International Society of Urological Pathology provided the foundation for the 2016 World Health Organization (WHO) classification of the renal tumors.The aim of this contribution is to review some of the major changes and additions to tumor variants and variations in the current classification of the renal cell neoplasms in adults.Evidence acquisition and Evidence synthesisSeveral publications report no recurrence or metastasis in patients with multilocular cystic renal cell carcinoma (RCC). Multilocular cystic renal neoplasm of low malignant potential is now the term recommended by the WHO for this lesion.A similar recommendation has been made in the current literature for hybrid oncocytic/chromophobe tumors (ie, oncocytic neoplasia of uncertain malignant potential) and for clear cell papillary renal cell carcinoma (ie, neoplasm of low malignant potential). Some of the latter tumors were referred to as renal angioadenomatous tumors.Papillary RCC has traditionally been subdivided into type 1 and type 2 papillary RCCs. Recent molecular studies suggest that type 2 papillary RCCs may not constitute a single well-defined entity. There are newly recognized epithelial renal tumor entities in the 2016 WHO classification such as succinate dehydrogenase-deficient RCC.Conclusions and Patient summaryThere are some additional variations in the tumor types that are not included in the WHO classification, however, worth knowing, such as clear cell RCC with hemangioblastoma-like features and unclassified RCC with medullary phenotype.     

Clinical Trials for Specific Renal Cancer Subtypes—The Time Will Come!

Renal cell cancer is a heterogeneous group of cancers with different histological phenotypes. Recent 2016 WHO classification acknowledges the genetic background of most renal cancer subtypes, whereas treatment for metastasized renal cell carcinoma (RCC) considers only clear cell and non–clear cell RCCs. Clear cell RCCs are characterized by the presence of at least three tumor suppressor genes on chromosome 3p. Owing to inactivation of von Hippel–Lindau (VHL), clear cell renal cancer produces the hypoxia-inducible factor–responsive vascular endothelial growth factor (VEGF). Other specific gene alterations have been identified in non–clear cell renal cancers, for example, PTEN, p53, and FLCN in chromophobe carcinomas; TFE3, TFEB, and MITF in translocation carcinomas; or MET and FH in variants of papillary RCC. Current treatments target VEGF or VEGF receptor using tyrosine kinase inhibitors, monoclonal antibodies, and mTOR inhibitors. Renal cancer immunotherapy using immune checkpoint inhibitors is currently tested in early clinical phases. We review current clinical trials on the basis of the molecular background of specific renal cancer subtypes.     

Beta defensin-1, parvalbumin,and vimentin: a panel of diagnostic immunohistochemical markers for renal tumors derived from gene expression profiling studies using cDNA microarrays

The common histopathologic subtypes of renal epithelial neoplasms include conventional, or clear cell, renal cell carcinoma (RCC), papillary RCC, chromophobe RCC, and renal oncocytoma. These subtypes differ clinically and pathologically, making accurate classification important. However, this differential diagnosis can be challenging because of overlapping morphology, suggesting a potential utility for ancillary immunohistochemical markers. We used cDNA microarrays to identify candidate markers for distinguishing renal tumor subtypes. In this report we validated differential expression of three candidate markers, beta defensin-1, parvalbumin, and vimentin, and evaluated the use of this immunohistochemical panel as a potential diagnostic tool. Consistent with our cDNA microarray data, chromophobe RCCs and oncocytomas exhibited similar expression profiles: 8 of 8 examples of each subtype were immunohistochemically positive for beta defensin-1 and parvalbumin and negative for vimentin (sensitivity 100%, specificity 100%); 4 of 7 papillary RCCs were positive for beta defensin-1, parvalbumin, and vimentin (sensitivity 57%, specificity 97%); and 22 of 23 conventional RCCs were negative for beta defensin-1, parvalbumin, or both markers (sensitivity 96%, specificity 96%) as well as positive for vimentin (sensitivity 83%). The immunohistochemical panel distinguished renal tumor subtypes with greater specificity than any marker used alone. This work demonstrates that a useful panel of immunohistochemical markers can be derived from differential gene expression profiles determined using cDNA microarrays.     

Von Hippel—Lindau病肾癌的临床特征分析

目的 探讨Von Hippel-Lindau（VHL）病肾癌的临床特点。方法回顾分析28例VHL病肾癌患者的临床资料。就初诊年龄、肿瘤部位、同时或异时癌、肿瘤的组织病理等与散发性肾癌进行比较。结果VHL肾癌初诊年龄44．6岁，双肾癌15例、多灶性肾癌16例、伴双侧多发肾囊肿20例。共切除87个实性肿瘤。术后病理：透明细胞癌86个，Fuhrman分级Ⅰ级73个、Ⅱ级12个、Ⅲ级1个；钙化结节1个。TNM分期ⅠA期、ⅠB期、Ⅱ期、Ⅲ期分别为8例、7例、8例和1例。与散发性肾癌组相比，VHL病肾癌组患者发病年龄早（P〈0．05），双肾多灶性肾癌及伴双侧多发肾囊肿比例高（P〈O．001），高级别肿瘤比例低（P〈O．05）。结论VHL病肾癌不同于散发性肾癌，有其独特的临床病理特征，这对该病诊断治疗具有一定指导价值。     

TGFβ_1及PCNA在肾细胞癌中的表达及其临床意义

目的 :探讨肾细胞癌中转化生长因子 β1 (TGFβ1 )及增殖细胞核抗原 (PCNA)的表达及其价值。方法 :采用免疫组织化学技术 (SP法 )对 46例肾细胞癌和 11例正常肾组织标本中 TGFβ1 、PCNA进行检测 ,并结合临床资料进行分析。结果 :肾癌组 TGFβ1 表达量较正常组高 (P <0 .0 5 ) ;PCNA在肾癌组高表达 (P <0 .0 1) ,且在高分期、高分级肾细胞癌中表达量较低分期、低分级肾细胞癌高 (P <0 .0 5 ) ;TGFβ1 表达量与 PCNA表达量呈负相关关系 (P <0 .0 1) ;TGFβ1 表达量低及 PCNA表达量高的肾癌患者预后差 (P <0 .0 5 )。结论 :TGFβ1 对处于增殖状态的肾细胞癌是一种重要负性调节因子 ,可抑制肾癌发展 ;TGFβ1 及 PCNA表达可作为判断肾细胞癌预后的指标     

Histological subtyping and nuclear grading of renal cell carcinoma and their implications for survival: a retrospective nation-wide study of 629 patients

OBJECTS: The aim of this study was to evaluate the prognostic significance of the current WHO histological subtyping and Fuhrman nuclear grading on the survival of patients with renal cell carcinoma (RCC). MATERIALS AND METHODS: A retrospective population-based study was carried out on all patients with a histopathologically confirmed diagnosis of RCC in Iceland between 1971 and 2000. Fuhrman grade, TNM stage, and survival were evaluated and multivariate analysis applied in order to determine prognostic factors. RESULTS: Out of 629 patients (387 males, 242 females, mean age 64 years), 558 (88.7%) had clear cell, 53 (8.4%) papillary, and 13 (2.1%) chromophobe RCC. Patient demographics were comparable for the two major subtypes, but chromophobe RCCs were larger in size and were diagnosed at a younger age. Clear cell RCCs were more often of higher grades (G3+G4, 48.4%) and at advanced TNM stages (III+IV, 59.3%) than papillary RCCs (22.6% and 34% respectively, p<0.001). Linear regression analysis showed a strong correlation between grade, tumor size, and stage (p<0.001). Chromophobe RCCs had a better survival in univariate analysis than both papillary and clear cell RCCs (84.6% vs. 66.5% and 54.9% 5-year disease specific survival, p<0.001). However, in the multivariate analysis, only the patient's age, calendar year of diagnosis, TNM stage, and nuclear grade were independent prognostic factors of survival. CONCLUSION: In this complete nation-wide series nuclear grading is important in predicting survival of patients with RCC. It is strongly related to both tumor size and stage, with stage being by far the strongest prognostic factor. Different histological subtypes confer different survival. However, in spite of the distinctive cytogenetic and molecular characteristics of the subtypes, the survival difference is to a large extent due to differences in grade and particularly stage.     

Spectrum of epithelial neoplasms in end-stage renal disease: an experience from 66 tumor-bearing kidneys with emphasis on histologic patterns distinct from those in sporadic adult renal neoplasia

Most (up to 71%) of renal cell neoplasms occurring in patients with end-stage renal disease (ESRD), particularly with acquired cystic disease of the kidney (ACDK), have been reported to be papillary renal cell carcinoma (RCC). Our initial experience with tumors in such a setting indicated that many tumors were histologically difficult to classify into the known subtypes of RCC or had features that were different from those in sporadically occurring RCCs. In this study on 66 ESRD kidneys (52 of which showed features of ACDK) removed because tumors were detected in them, we found two major groups of RCC. Overall, there were 261 grossly identified tumors in these kidneys, and many additional tumors were observed on microscopic evaluation in some. Of the two major groups of RCCs, one consisted of tumors similar to those seen in sporadic settings (ie, clear-cell, papillary, and chromophobe RCC), and these formed the dominant mass in 12 (18%), 10 (15%), and 5 (8%) of the 66 kidneys, respectively. The other group consisted of two subtypes of RCC that appear quite unique to ESRD. The more common tumor that we have designated as "acquired cystic disease-associated RCC" was seen as the dominant mass in 24 (36%) of 66 of the kidneys, and it formed the most common tumor type among the smaller nondominant masses, as well. It was characterized by a typical microcystic architecture, eosinophilic cytoplasm with Fuhrman's grade 3 nuclei, and frequent association with intratumoral oxalate crystals. Additionally, these tumors frequently, but usually focally, exhibited papillary architecture, and clear cytoplasm. These tumors occurred only in kidneys with ACDK, and not in noncystic ESRD. The other category was "clear-cell papillary RCC of the end-stage kidneys," present as the dominant mass in 15 (23%) of the 66 kidneys and occurring in both the ACDK and noncystic ESRD. These predominantly cystic tumors showed prominent papillary architecture with purely clear-cell cytology. Immunohistochemical studies in tumors with histology similar to the known subtypes of sporadic RCC showed immunoprofiles similar to that reported in sporadically occurring tumors. The two subtypes of RCC unique to ESRD had distinctive immunoprofiles supporting their separate morphologic subcategorization. Only the acquired cystic disease-associated RCC showed lymph node metastases in 2 cases and sarcomatoid features in 2 more cases. One of the latter 2 died with widespread metastatic disease within 34 months of nephrectomy. Thus, a broad spectrum of renal cell tumors exist in ESRD, only some of which resemble the sporadic RCCs. Acquired cystic disease-associated RCC is the commonest tumor subtype in ESRD, and biologically it appears to be more aggressive than the other tumor subtypes in ESRD.     

Molecular Confirmation of t(6;11)(p21;q12) Renal Cell Carcinoma in Archival Paraffin-embedded Material Using a Break-apart TFEB FISH Assay Expands its Clinicopathologic Spectrum

A subset of renal cell carcinomas (RCCs) is characterized by t(6;11)(p21;q12), which results in fusion of the untranslated Alpha (MALAT1) gene to the TFEB gene. Only 21 genetically confirmed cases of t(6;11) RCCs have been reported. This neoplasm typically demonstrates a distinctive biphasic morphology, comprising larger epithelioid cells and smaller cells clustered around basement membrane material; however, the full spectrum of its morphologic appearances is not known. The t(6;11) RCCs differ from most conventional RCCs in that they consistently express melanocytic immunohistochemical (IHC) markers such as HMB45 and Melan A and the cysteine protease cathepsin K but are often negative for epithelial markers such as cytokeratins. TFEB IHC has been proven to be useful to confirm the diagnosis of t(6;11) RCCs in archival material, because native TFEB is upregulated through promoter substitution by the gene fusion. However, IHC is highly fixation dependent and has been proven to be particularly difficult for TFEB. A validated fluorescence in situ hybridization (FISH) assay for molecular confirmation of the t(6;11) RCC in archival formalin-fixed, paraffin-embedded material has not been previously reported. We report herein the development of a break-apart TFEB FISH assay for the diagnosis of t(6;11)(p21;q12) RCCs. We validated the assay on 4 genetically confirmed cases and 76 relevant expected negative control cases and used the assay to report 8 new cases that expand the clinicopathologic spectrum of t(6;11) RCCs. An additional previously reported TFEB IHC-positive case was confirmed by TFEB FISH in 46-year-old archival material. In conclusion, TFEB FISH is a robust, clinically validated assay that can confirm the diagnosis of t(6;11) RCC in archival material and should allow a more comprehensive clinicopathologic delineation of this recently recognized neoplastic entity.     

Renal cell carcinoma of native kidney in renal transplant recipients

OBJECTIVE: To evaluate the prevalence, prognosis and possible risk factors of renal cell carcinoma (RCC) of the native kidney in renal transplant recipients. PATIENTS AND METHODS: We retrospectively re-examined the follow-up data of 373 consecutive renal transplant recipients at our institution between August 1993 and September 2004. We collected the data of all de novo RCC of the native kidney in the current analysis. RESULTS: Of the 373 patients examined, 12 tumours of the native kidney were diagnosed in 10 individuals. The mean ages at transplantation and diagnosis were 33 and 45.8 years, respectively. Thirteen malignancies were discovered fortuitously. Among the renal ultrasonograms there were two false-negative results. The mean tumour size was 21 mm. Nephrectomy was performed in all cases. Among the 12 kidney malignancies, there were five conventional RCCs and seven papillary RCCs. Half of all tumours were Furhman Grade 3 lesions, and pT1aN0M0 tumours also accounted for all malignancies in the current cohort. One of the 10 patients died, from progression of metastases 6 years after diagnosis. One patient had a local recurrence 2 years after diagnosis. The other eight patients were alive with no evidence of disease at the time of the current report. No significant relationship was detected between RCC occurrence and clinical patient characteristics. CONCLUSIONS: There appears to be a greater risk of RCC of the native kidney in patients with end-stage renal disease. The present results suggest that an annual examination of the native kidney before and after renal transplantation is essential.     

Towards a new WHO classification of renal cell tumor: what the clinician needs to know—a narrative review

In 1952, renal cell carcinomas had been divided into 2 categories—clear cell or granular cell—depending upon their cytoplasmic staining characteristics. In the following years, the inventory of renal epithelial tumors has expanded by the addition of tumors named by their architectural pattern (i.e., papillary RCC, tubulocystic RCC), anatomic location (i.e., collecting duct carcinoma, renal medullary carcinoma), associated diseases (i.e., acquired cystic disease-associated RCCs). With the extensive application of molecular diagnostic techniques, it becomes possible to detect genetic distinctions between various types of renal neoplasm and discover new entities, otherwise misdiagnosed or diagnosed as unclassified RCC. Some tumors such as ALK rearrangement-associated RCC, MiT family translocation renal carcinomas, SDH-deficient renal cancer or FH-deficient RCC, are defined by their molecular characteristics. The most recent World Health Organization (WHO) classification of renal neoplasms account for more than 50 entities and provisional entities. New entities might be included in the upcoming WHO classification. The aim of this review is to summarise and discuss the newly acquired data and evidence on the clinical, pathological, molecular features and on the prognosis of new RCC entities, which will hopefully increase the awareness and the acceptance of these entities among clinicians and improve prognostication for individual patients.     

Diagnosing primary and metastatic renal cell carcinoma: the use of the monoclonal antibody 'Renal Cell Carcinoma Marker'.

The diagnosis of primary or metastatic renal cell carcinoma (RCC) can be difficult, especially in small biopsies, because of the wide variety of histologic appearances and clinical presentations that RCC can assume. An immunomarker specific for RCC is currently not available. We tested the relevant diagnostic use of the Renal Cell Carcinoma Marker (RCC Ma), a monoclonal antibody, against a normal human proximal tubular brush border antigen. Immunostaining using RCC Ma and the avidin-biotin-peroxidase complex technique was performed on archival tissues from primary and metastatic tumors of renal or nonrenal origin. A total of 122 of 153 primary RCCs (79.7%) were positive [clear cell (84%), papillary (96%), chromophobe (45%), sarcomatoid (25%), and collecting duct (0%)], with > or =10% of tumor cells stained in 93% of cases. None of the 64 primary renal tumors other than RCC, including 15 oncocytomas, was positive. Fifteen of 146 (10.2%) nonrenal primary tumors were positive (5 of 17 breast tumors, 8 of 8 parathyroid adenomas, and 2 of 7 embryonal carcinomas). Forty-two of 63 (67%) metastatic RCCs were positive with > or =10% of cells being stained in 83% of them. Two of 108 (2%) metastases from tumors other than RCCs were positive, both of which were metastatic breast carcinomas; however, only 10% (2 of 19) of metastatic breast carcinomas were positive. RCC Ma is an excellent marker for primary RCC, which should facilitate its diagnosis in a small biopsy. Although RCC Ma remains highly specific (98%) for metastatic RCC, a negative result may not rule out metastatic RCC because of a rather low sensitivity and a focal staining pattern in some of the positive cases. RCC Ma may also facilitate the differential diagnosis between oncocytoma and other types of RCC when they are composed mostly of eosinophilic cells.     

Emerging Entities in Renal Neoplasia

This article reviews emerging entities in renal epithelial neoplasia, including tubulocystic carcinoma, clear-cell–papillary renal cell carcinoma (RCC), thyroid-like follicular RCC, ALK-related RCC, translocation RCC, acquired cystic disease–related RCC, succinate dehydrogenase–deficient RCC, and hereditary leiomyomatosis-RCC syndrome–associated RCC. Many of these rarer subtypes of RCC were recently studied in more depth and are included in the upcoming version of the World Health Organization classification of tumors. Emphasis is placed on common gross and morphologic features, differential diagnoses, use of ancillary studies for making accurate diagnoses, molecular alterations, and predicted biologic behavior based on previous studies.     

Calcium oxalate deposition in renal cell carcinoma associated with acquired cystic kidney disease: a comprehensive study

The main complication of acquired cystic kidney disease (ACKD) is frequent development of renal tumors, including renal cell carcinoma (RCC). Intratumoral deposition of calcium oxalate (CaOx) is a distinct feature of ACKD-associated RCCs, but several features of this type of RCC are not known. Features of the 30 end-stage renal disease (ESRD)-associated RCCs identified within a 13-year period, including eight with CaOx deposition, were analyzed. Pathologic and clinical features of CaOx positive (+) and negative (-) RCCs were evaluated and compared. The CaOx+ RCCs showed higher tendency for bilaterality and multifocality. Seven tumors displayed distinctive morphologic features characterized by tumor cells with ill-defined cell membrane, abundant granular eosinophilic cytoplasm, large nuclei, and prominent nucleoli. One tumor was of clear cell type. Regardless of histologic type, all tumors displayed a proximal tubular differentiation. No significant difference was noted for tumors' stage, proliferation, and apoptosis rate between the CaOx+ and CaOx- RCCs. CaOx+ RCCs account for a significant portion of all ESRD-associated RCCs. The majority of these RCCs display a distinctive morphologic profile. Proximal tubular cell differentiation in conjunction with ESRD-mediated high serum level may be pathogenetically important for intratumoral CaOx deposition. These RCCs seems to have a relatively good prognosis.     

Distribution of cytokeratins and vimentin in adult renal neoplasms and normal renal tissue: potential utility of a cytokeratin antibody panel in the differential diagnosis of renal tumors

Adult renal epithelial neoplasms (RENs) comprise several distinct clinicopathologic entities with potential prognostic and therapeutic differences. Individual cases can show overlapping morphologic features, necessitating the use of ancillary methods. The purpose of this study was to determine the diagnostic utility of cytokeratin (CK) subtype expression pattern in a wide range of adult RENs. RENs (including clear cell [conventional] renal cell carcinoma (RCC), papillary RCC, chromophobe RCC, renal oncocytoma, collecting duct carcinoma (CDC), renal medullary carcinoma (RMC), urothelial carcinoma, metanephric adenoma (MA), tubulocystic carcinoma (TC) (also known as low-grade collecting duct carcinoma), and mucinous tubular and spindle cell carcinoma) were immunostained for CK subtypes (CK5/CK6, 7, 8, 13, 14, 17, 18, 19, 20), high molecular weight CKs 1, 5, 10, 14 (HMWCK), and vimentin (Vim). The expression pattern of normal kidney was also examined and correlated with RENs. Although there is some overlap, subtypes of RENs show distinctive CK expression profiles that may be useful in several differential diagnostic settings. Clear cell RCCs typically showed a restricted expression pattern of CK8, CK18 and Vim. Papillary RCCs typically expressed CK7, CK8, CK18, CK19, and Vim and could be distinguished from MA (CK7-). Chromophobe RCCs were typically CK7+, CK8+, CK18+, and Vim-, and could be distinguished from oncocytomas (typically CK7-). In oncocytomas, nonspecific staining of unblocked endogenous biotin is a potentially significant diagnostic pitfall. CDC, RMC, and TC demonstrated similar CK expression profiles (with the exception of HMWCK expression limited to CDC), supporting a close relationship between these entities. A panel of CK5/CK6, CK17, and Vim may be helpful in distinguishing CDC (typically CK5/CK6-, CK17-, Vim+) and urothelial carcinoma (typically CK5/CK6+, CK17+, Vim-). In conclusion, CK expression patterns may be helpful in several differential diagnostic situations when dealing with adult RENs.     

Pilot study of non‐contrast‐enhanced MRI vs. ultrasound in renal transplant recipients with acquired cystic kidney disease: a prospective intra‐individual comparison

The incidence of renal cell carcinoma (RCC) after kidney transplantation is 15‐fold increased. Acquired cystic kidney disease (ACKD) is one of the known risk factors. We performed a small pilot study to assess the role of non‐enhanced magnetic resonance imaging (MRI) as a tool for intensified screening in renal transplant recipients with ACKD. Renal ultrasound was used to assess the native kidneys of 215 renal transplant recipients. Thirty patients with 54 kidneys, fulfilling the criteria of ACKD, underwent non‐enhanced MRI at 1.5T using T2‐ and T1‐weighed as well as diffusion‐weighted sequences with a high spatial resolution. Among the 54 kidneys assessed by both methods, three RCCs were identified (6%). Of those, one RCC was detected by both imaging methods (33%), while two RCCs were diagnosed by MRI alone (67%). MRI identified an additional four proteinaceous or hemorrhagic cysts that did not fulfill the criteria for RCC but were classified as suspicious. All of these lesions were stable in size and appearance in follow‐up studies. In conclusion, non‐enhanced MRI was more sensitive than ultrasound in identifying RCCs and lesions suspicious for RCC and thus appears to be a useful secondary screening tool in patients with ACKD after renal transplantation.     

Kit (CD117) immunoreactivity is rare in renal cell and upper urinary tract transitional cell carcinomas

OBJECTIVE: To investigate the presence of Kit (CD117), a transmembrane tyrosinase-kinase receptor, in primary and metastatic renal cell carcinomas (RCCs) and upper urinary tract transitional cell carcinomas (TCCs). MATERIALS AND METHODS: In human neoplasia, overexpression of Kit has been related to cell proliferation, differentiation, adhesion and control of apoptosis. If present, Kit may provide a suitable target for tumour therapy. Formalin-fixed and paraffin-embedded specimens of 180 primary and 58 metastatic RCCs and 54 upper urinary tract TCCs were immunostained for Kit (CD117) using a tissue microarray technique. RESULTS: In RCCs, immunoreactivity for CD117 was detected in only two of 23 (9%) chromophobe tumours, whereas all 137 conventional and 20 papillary subtypes, and metastatic RCC tissues, lacked CD117 immunoreactivity. In TCCs, CD117 expression of <10% cancer cells was found in two of 53 (4%) cases. Stromal mast cells served as a positive control and showed specific immunostaining. CONCLUSION: Kit immunoreactivity is infrequent in both RCCs and upper urinary tract TCCs. Thus, routine screening of tumour tissues for Kit by immunohistochemistry appears to be cost-ineffective and cannot be recommended. Moreover, the lack of substantial Kit immunoreactivity in both primary and metastatic carcinomas does not provide a rationale to investigate imatinib mesylate therapy in clinical trials including patients with advanced disease.     

2009 update on the classification of renal epithelial tumors in adults

The classification of kidney tumors in adults expands rapidly with new categories recently incorporated. This will result in the modification of the current 2004 World Health Organization (WHO) classification of the adult renal epithelial neoplasms. Emphasis should be placed in defining risk groups categorized as malignant or benign tumors, including a category of tumors with low malignant potential to accommodate recently recognized categories with extremely good prognosis after surgery. Unusual tumors such as familial renal cell carcinoma (RCC), translocation RCC, renal cell carcinoma after neuroblastoma, tubular mucinous and spindle cell carcinoma, and mixed epithelial and stromal tumors are also presented. A number of recently described entities and morphologic variants of classical categories deserve recognition since they can be important in differential diagnosis. This review emphasizes clinical, pathological and genetic features defining renal epithelial tumors in adults.     

肾肿瘤剜除术治疗肾细胞癌、肾血管平滑肌脂肪瘤

目的探讨肾肿瘤剜除术治疗肾细胞癌及肾血管平滑肌脂肪瘤的疗效。方法回顾分析15例在我院进行肾肿瘤剜除术的肾细胞癌及肾血管平滑肌脂肪瘤患者的临床及病理资料。结果全部肾肿瘤均成功剜除，平均热缺血时间为15min，术中肿瘤剜除面平均出血25ml，术后无继发出血，无急性肾小管坏死、慢性肾功能不全及尿瘘等并发症发生。术后平均随访时间为2．5年，均未见肿瘤复发或转移。依据2003AJCC肾癌分期方法，所有肾癌患者均为Tla期，组织学形态为透明细胞癌。病理分级按Fuhrman标准为G1。结论肾肿瘤剜除术对有假性包膜的Tla肾细胞癌和肾血管平滑肌脂肪瘤是有效和安全的，术后并发症少，可以最大程度地保留肾脏功能。     

Construction of diagnostic and subtyping models for renal cell carcinoma by genome-wide DNA methylation profiles

BackgroundRenal cell carcinoma (RCC) is one of the most common urological cancers and has a poor prognosis. RCC is classified into several subtypes, among which kidney renal clear cell carcinoma (KIRC) and kidney renal papillary cell carcinoma (KIRP) are the two most common subtypes. Due to the lack of adequate screening and comparative analysis of RCC subtypes, effective diagnosis and treatment strategies have not yet been achieved.MethodsIn this study, 450K methylation array data were collected from The Cancer Genome Atlas (TCGA). The ‘limma moderated t-test’ and LASSO were used to construct diagnostic and subtyping models, and survival analysis was conducted online by GEPIA.ResultsWe built a model with 15 methylation sites, which showed high diagnostic and subtyping performance in specificity and sensitivity. At the same time, for potential clinical usability, we calculated the diagnostic and subtyping scores to classify RCC from normal tissue and distinguish the different RCC subtypes. Additionally, the CpG sites were mapped to their corresponding genes, which could also be used to predict the prognosis of RCC.ConclusionsDifferent methylation sites can be used as diagnostic and subtyping markers that are specific to RCC and RCC subtypes (KIRC and KIRP) with high sensitivity and accuracy.