Clear cell papillary renal cell carcinoma, renal angiomyoadenomatous tumor, and renal cell carcinoma with leiomyomatous stroma relationship of 3 types of renal tumors: a review

Biallelic ELOC-Inactivated Renal Cell Carcinoma: Molecular Features Supporting Classification as a Distinct Entity

Approximately 70% of clear cell renal cell carcinoma (ccRCC) is characterized by the biallelic inactivation of von Hippel-Lindau (VHL) on chromosome 3p. ELOC-mutated (Elongin C-mutated) renal cell carcinoma containing biallelic ELOC inactivations with chromosome 8q deletions is considered a novel subtype of renal cancer possessing a morphologic overlap with ccRCC, renal cell carcinoma (RCC) with fibromyomatous stroma exhibiting Tuberous Sclerosis Complex (TSC)/mammalian Target of Rapamycin (mTOR) mutations, and clear cell papillary tumor. However, the frequency and consequences of ELOC alterations in wild-type VHL and mutated VHL RCC are unclear. In this study, we characterize 123 renal tumors with clear cell morphology and known VHL mutation status to assess the morphologic and molecular consequences of ELOC inactivation. Using OncoScan and whole-exome sequencing, we identify 18 ELOC-deleted RCCs, 3 of which contain ELOC mutations resulting in the biallelic inactivation of ELOC. Biallelic ELOC and biallelic VHL aberrations were mutually exclusive; however, 2 ELOC-mutated RCCs showed monoallelic VHL alterations. Furthermore, no mutations in TSC1, TSC2, or mTOR were identified in ELOC-mutated RCC with biallelic ELOC inactivation. Using High Ambiguity Driven biomolecular DOCKing, we report a novel ELOC variant containing a duplication event disrupting ELOC-VHL interaction alongside the frequently seen Y79C alteration. Using hyper reaction monitoring mass spectrometry, we show RCCs with biallelic ELOC alterations have significantly reduced ELOC expression but similar carbonic anhydrase 9 and vascular endothelial growth factor A expression compared with classical ccRCC with biallelic VHL inactivation. The absence of biallelic VHL and TSC1, TSC2, or mTOR inactivation in RCC with biallelic ELOC inactivation (ELOC mutation in combination with ELOC deletions on chromosome 8q) supports the notion of a novel, molecularly defined tumor entity.

TSC/MTOR mutated renal cell carcinoma with leiomyomatous stroma is a distinct entity: a comprehensive study of 12 cases

The 2016 World Health Organization (WHO) Classification of Tumors of the Urinary System includes renal cell carcinoma (RCC) with leiomyomatous stroma (RCC-LS) as a provisional category. Recent studies have shown that this category includes at least 4 subtypes: clear cell (CCRCC), clear cell papillary renal cell tumor (CCPRCT), ELOC (TCEB1) mutated, and a subtype of RCC with TSC/MTOR mutations. The most recent 2022 World Health Organization (WHO) Classification of Tumors of the Urinary System includes ELOC mutated RCC-LS as a distinct entity but does not address any other renal tumors with smooth muscle stroma. We reviewed >500 cases of RCC with clear cell phenotype and identified 12 cases that exhibited prominent smooth muscle stroma, of which 4 of the cases had been previously reported. Review of the H&E revealed that all of the tumors were circumscribed with nested, solid, tubular, and tubulopapillary architecture. The epithelium was intimately embedded in the rich smooth muscle stroma. WHO/ISUP grade corresponded to grade 3 and 4. Nuclei were randomly distributed and the cytoplasm had predominantly clear and occasionally flocculent appearance. Immunohistochemically, all the cases showed membranous CAIX staining, although the pattern was combined cup and box-shaped. CK7 was positive in all cases ranging from 25% to 100% of cells. Membranous and apical staining of CD10 was present in all cases. Next generation sequencing (NGS) of these cases identified mutations in TSC1 (n = 4), TSC2 (n = 3), and MTOR (n = 4) with one case exhibiting loss of TSC1. This descriptive study, although small, demonstrates the difficulty in applying the current WHO provisional criteria at a single institution. Given the heterogeneity seen with these cases, we suggest following up an immunohistochemical panel of CAIX, CK7, and CD10 with molecular diagnostic studies to assist in the diagnosis of TSC/MTOR associated RCC-LS, which we believe is a distinct entity.

How New Developments Impact Diagnosis in Existing Renal Neoplasms

In recent years, several emerging diagnostic entities have been described in renal cell carcinoma (RCC). However, our understanding of well-known and established entities has also grown. Clear cell papillary RCC is now relabeled as a tumor rather than carcinoma in view of its nonaggressive behavior. Renal tumors with a predominantly infiltrative pattern are very important for recognition, as most of these have aggressive behavior, including fumarate hydratase-deficient RCC, SMARCB1-deficient medullary carcinoma, collecting duct carcinoma, urothelial carcinoma, and metastases from other cancers.

Contemporary Clinical Definitions, Differential Diagnosis, and Novel Predictive Tools for Renal Cell Carcinoma

Despite significant progress regarding clinical detection/imaging evaluation modalities and genetic/molecular characterization of pathogenesis, advanced renal cell carcinoma (RCC) remains an incurable disease and overall RCC mortality has been steadily rising for decades. Concomitantly, clinical definitions have been greatly nuanced and refined. RCCs are currently viewed as a heterogeneous series of cancers, with the same anatomical origin, but fundamentally different metabolisms and clinical behaviors. Thus, RCC pathological diagnosis/subtyping guidelines have become increasingly intricate and cumbersome, routinely requiring ancillary studies, mainly immunohistochemistry. Meanwhile, RCC-associated-antigen targeted systemic therapy has been greatly diversified and emerging, novel clinical applications for RCC immunotherapy have already reported significant survival benefits, at least in the adjuvant setting. Even so, systemically disseminated RCCs still associate very poor clinical outcomes, with currently available therapeutic modalities only being able to prolong survival. In lack of a definitive cure for advanced RCCs, integration of the amounting scientific knowledge regarding RCC pathogenesis into RCC clinical management has been paramount for improving patient outcomes. The current review aims to offer an integrative perspective regarding contemporary RCC clinical definitions, proper RCC clinical work-up at initial diagnosis (semiology and multimodal imaging), RCC pathological evaluation, differential diagnosis/subtyping protocols, and novel clinical tools for RCC screening, risk stratification and therapeutic response prediction.

Evaluating Established Roles, Future Perspectives and Methodological Heterogeneity for Wilms’ Tumor 1 (WT1) Antigen Detection in Adult Renal Cell Carcinoma, Using a Novel N-Terminus Targeted Antibody (Clone WT49)

Renal cell carcinoma (RCC) is arguably the deadliest form of genitourinary malignancy and is nowadays viewed as a heterogeneous series of cancers, with the same origin but fundamentally different metabolisms and clinical behaviors. Immunohistochemistry (IHC) is increasingly necessary for RCC subtyping and definitive diagnosis. WT1 is a complex gene involved in carcinogenesis. To address reporting heterogeneity and WT1 IHC standardization, we used a recent N-terminus targeted monoclonal antibody (clone WT49) to evaluate WT1 protein expression in 56 adult RCC (aRCC) cases. This is the largest WT1 IHC investigation focusing exclusively on aRCCs and the first report on clone WT49 staining in aRCCs. We found seven (12.5%) positive cases, all clear cell RCCs, showing exclusively nuclear staining for WT1. We did not disregard cytoplasmic staining in any of the negative cases. Extratumoral fibroblasts, connecting tubules and intratumoral endothelial cells showed the same exclusively nuclear WT1 staining pattern. We reviewed WT1 expression patterns in aRCCs and the possible explanatory underlying metabolomics. For now, WT1 protein expression in aRCCs is insufficiently investigated, with significant discrepancies in the little data reported. Emerging WT1-targeted RCC immunotherapy will require adequate case selection and sustained efforts to standardize the quantification of tumor-associated antigens for aRCC and its many subtypes.

Characteristics of Clear Cell Papillary Renal Cell Carcinoma (ccpRCC)

Renal cell carcinomas (RCCs) is a group of various malignant tumours of the renal cortex displaying distinct clinical, morphologic, and genetic features. Clear cell papillary renal cell carcinoma (ccpRCC), belonging to this group, shares morphologic features with both clear cell renal cell carcinoma (ccRCC) and papillary renal cell carcinoma (pRCC) and therefore, more strict diagnostic criteria should be developed to avoid misdiagnosis. Despite overlapping features, ccpRCC has also distinct clinical behaviour, histologic characteristics (morphologic and immunohistochemical), and genomic features. The concepts concerning this tumour are constantly developing since its biological potential and molecular basis remains to be fully unravelled. First reports indicated the presence of ccpRCC in end-stage renal disease, and they underlined the enriched development in this group of patients; however, currently, it is known that such tumours can also occur spontaneously in the normal kidney. Numerous studies have demonstrated that clinical outcomes and prognosis of ccpRCC patients is highly favourable. Till now, no convincing evidence of metastatic ccpRCC or death caused by the disease has been found. Therefore, it is of high importance to correctly differentiate ccpRCC from other subtypes of RCC with a much worse prognosis and to introduce appropriate management.

[Renal carcinoma with leiomyomatous stroma and osseous metaplasia from a patient diagnosed with a tuberous sclerosis complex]

Renal cell carcinoma with leiomyomatous stroma is a rare and poorly described histopathological entity. Here we report a unique case with osseous metaplasia, in a 31-year-old man recently diagnosed with a tuberous sclerosis complex (TSC2 gene mutation). Partial nephrectomy was performed. Histologically, the epithelial component was made up of papillary and alveolar structures with clear to eosinophilic cytoplasm, and basally located nuclei. The cells are surrounded by an abundant smooth muscle stroma with focally osseous metaplasia. The tumor was positive for carbonic anhydrase IX, cytokeratin 7, cytokeratin 20, and CD10, and negative for TFE3. This emerging entity is highly correlated to tuberous sclerosis complex, which justifies a screening for the syndrome when this diagnosis is made.

Clear Cell Papillary Renal Cell Carcinoma Shares Distinct Molecular Characteristics and may be Significantly Associated With Higher Risk of Developing Second Primary Malignancy

Traditionally, clear cell papillary renal cell carcinoma (ccpRCC) was considered to share similar molecular and histological characteristics with clear cell renal cell carcinoma (ccRCC) and papillary renal cell carcinoma (pRCC). Here we aimed to identify somatic and germline variants of ccpRCC. For this purpose, we conducted whole-exome sequencing to detect somatic variants in the tissues of 18 patients with pathologically confirmed ccpRCC, who underwent surgical treatment at Fudan University Shanghai Cancer Center. Targeted sequencing was conducted to detect germline variants in paired tumor or normal tissues or blood. Somatic and germline variants of ccRCC and Renal cell carcinoma included in The Cancer Genome Atlas data and other published data were analyzed as well. The molecular profiles of ccpRCC, ccRCC and pRCC were compared. Among the 387 somatic variants identified, TCEB1 (3/18) and VHL (3/18) variants occurred at the highest frequencies. Germline mutation detection showed that nine variants associated with Fanconi anemia (VAFAs) pathway (FANCA, 6/18; FANCI, 3/18) were identified in 18 ccpRCC patients. Among ccpRCC patients with VAFAs, five out of eight patients had second primary malignancy or family history of cancer. Somatic variants characteristics may distinguish ccpRCC from ccRCC or pRCC and germline VAFAs may be a molecular characterization of ccpRCC. Compared with ccRCC or pRCC, ccpRCC patients may be significantly correlated with higher risk of developing second primary malignancy.

Classification of renal cell tumors – current concepts and use of ancillary tests: recommendations of the Brazilian Society of Pathology

Classification of renal cell carcinomas has become more challenging. The 2016 WHO classification included 14 different subtypes and 4 emerging/provisional entities, and recent literature indicates new entities to be incorporated. Nomenclature is based on cytoplasmic appearance, architecture, combination of morphologies, anatomic location, underlying disease, familial syndromes, and specific genetic alterations. Immunohistochemistry is useful in selected cases while it can be insufficient in entities that require molecular confirmation of a specific gene alteration. The aim of these recommendations is to provide a reasonable and optimized approach for the use of ancillary tests in subtyping renal tumors, particularly in resource-limited settings.

Clear cell papillary renal cell carcinoma: an update after 15 years

Fifteen years since the first recognition of clear cell papillary renal cell carcinoma, this distinct renal tumour type is now well accepted as a distinct entity in major classification schemes. It occurs both with and without end-stage renal disease and may be multifocal or bilateral in both scenarios. Recognisable morphological features include clear cells lining branching glands and variable papillary formations with nuclear alignment. Most tumours are small (pT1a) and nucleolar grade 1-2. Immunohistochemistry consistently shows positivity for carbonic anhydrase IX and cytokeratin 7, and often high molecular weight cytokeratin or GATA3, the latter suggesting distal nephron phenotype. Labeling for AMACR and CD10 is consistently negative or minimal. Despite a resemblance to clear cell renal cell carcinoma, molecular alterations of VHL and chromosome 3p are typically lacking, with debatable rare exceptions. Potential mimics include clear cell renal cell carcinoma (with branching architecture or nuclear alignment), papillary renal cell carcinoma with clear cytoplasm, or rarely MITF family translocation renal cell carcinoma. Clinical behaviour is highly favourable with rare, debatable reports of aggressive behaviour. Combined with striking similarity to several extrarenal benign neoplasms, it would be reasonable to reclassify this entity as a benign or low malignant potential neoplasm. Using the nomenclature of the extrarenal counterparts, clear cell papillary (cyst)adenoma is proposed.

"Renal Cell Carcinoma With Leiomyomatous Stroma" Harbor Somatic Mutations of TSC1, TSC2, MTOR, and/or ELOC (TCEB1): Clinicopathologic and Molecular Characterization of 18 Sporadic Tumors Supports a Distinct Entity

Renal cell carcinoma with (angio) leiomyomatous stroma (RCCLMS) is included as a provisional entity in the 2016 World Health Organization (WHO) classification of renal epithelial neoplasia; however, debate remains whether it represents a distinct entity or a heterogenous group of renal cell carcinomas (RCCs) with overlapping morphology. Also, its relationship to similar tumors occurring in the setting of tuberous sclerosis complex (TSC) is not fully addressed. We analyzed the clinicopathologic, immunohistochemical, and molecular characteristics of 23 sporadic RCCs associated with smooth muscle stroma and classified them into 2 groups, independent of molecular results: (1) RCCLMS (n=18) and (2) clear cell renal cell carcinoma (CCRCC) (n=5). The classification of a case as "RCCLMS" was based on morphologic comparison with 5 "index" RCCs from 3 patients with TSC showing similar features and the presence of diffuse CK7 expression. To investigate mutational and copy number alterations, a 170-gene solid tumor panel was utilized to sequence 14 RCCLMSs and control of 5 CCRCCs. Also, 4 RCCLMSs, suspicious for chromosome 8 monosomy, were further evaluated by a broader 479 gene sequencing panel that included ELOC (also referred to as TCEB1). Clinical information and follow-up data were obtained from electronic medical records. The mean age of patients with RCCLMS was 52 years (range, 33 to 69) with male:female ratio of 1:2. Macroscopically, all tumors were solitary and predominantly (82%) tan/red, circumscribed, and solid. The average tumor size was 2.3 cm (range, 1.1 to 4.5). Microscopically, the distinctive feature included tumor nodules of elongated and frequently branching tubules lined by cells with voluminous clear to mildly eosinophilic cytoplasm (100%), separated by focal to prominent smooth muscle stroma. Additional frequently identified features included: biphasic pattern of collapsed acini surrounding tubules with voluminous cytoplasm (50%), focal papillary architecture (39%), peritumoral lymphoid aggregates (39%), and hemosiderin-laden macrophages (33%). All 11 (100%) RCCLMSs with available staging information were pT1; 78% were WHO/International Society of Urologic Pathology (ISUP) grade 2 and 22% grade 3. Immunophenotypically, RCCLMSs were characterized by diffuse CK7, CAM5.2 and CD10 reactivity (100%). All patients with available follow-up (n=10) were alive and without disease progression after a mean and median follow-up of 25.2 (range: 1 to 58) and 25 months, respectively. The molecular results showed recurrent mutations in all RCCLMS: TSC1 (4), TSC2 (4), MTOR (6), and/or ELOC (2). Five control CCRCCs demonstrated primary alterations in VHL gene, while all 14 RCCLMS cases tested had intact VHL gene. Of 2 RCCLMSs with confirmed monosomy 8, 1 showed a hotspot ELOC mutation without TSC/MTOR mutations, and 1 showed a previously undescribed 3-bp in-frame ELOC deletion, along with a truncating TSC1 mutation. In conclusion, RCCLMS, as defined herein, harbors recurrent mutations of TSC1/TSC2, MTOR, and/or ELOC, consistent with hyperactive MTOR complex. Our findings argue that these tumors represent the sporadic counterpart to morphologically identical tumors occurring in TSC patients. Finally, the data support that RCCLMS is a novel subtype of RCC with unique morphologic, immunohistochemical, and molecular characteristics that is distinct from CCRCC and clear cell-papillary RCC.

Renal Cell Carcinoma with Clear Cell Papillary Features: Perspectives of a Differential Diagnosis

Thirty-one cases of low-grade renal cell carcinoma (RCC) with clear cells and tubulopapillary/papillary architecture were analyzed retrospectively with immunohistochemical and genetic markers to gain more experience with the differential diagnosis of such cases. All samples coexpressed CK7 and CA9; the TFE3 or TFEB reactions were negative; the CD10 and the AMACR stainings were negative in 27 cases and 30 cases, respectively. The FISH assays for papillary RCC, available in 27 cases, and deletion of chromosome 3p, available in 29 cases, gave negative results. The results for 3p deletion, VHL gene mutation or VHL gene promoter region hypermethylation testing, along with the diffuse CD10-positivity in 2 cases confirmed 21 cases as clear cell papillary RCC (CCPRCC; CK7+, CA9+; no 3p loss, no VHL abnormality) and 10 cases as clear cell RCC (CCRCC; CK7+, CA9+; no 3p loss, VHL abnormality mutation/hypermethylation present). In CCPRCCs, the representative growth pattern was branching tubulo-acinar, commonly accompanied by cyst formation. The linear nuclear arrangement or cup-shaped staining of CA9 did not necessarily indicate CCPRCC, and the absence of these did not exclude the diagnosis of CCPPRC. One tumor infiltrated the renal sinus; the others exhibited pT1 stage; and metastatic outcome was not recorded. The CCRCC cases were in pT1 stage; 6 exhibited cup-shaped staining of CA9, and 1 displayed lymph node metastasis at the time of surgery. Distant metastatic disease was not observed. In summary, the VHL abnormalities distinguished the subset of CCRCC with diffuse CK7-positivity and no 3p loss from cases of CCPRCC.

Molecular Genetics of Renal Cell Tumors: A Practical Diagnostic Approach

Renal epithelial cell tumors are composed of a heterogeneous group of tumors with variable morphologic, immunohistochemical, and molecular features. A "histo-molecular" approach is now an integral part of defining renal tumors, aiming to be clinically and therapeutically pertinent. Most renal epithelial tumors including the new and emerging entities have distinct molecular and genetic features which can be detected using various methods. Most renal epithelial tumors can be diagnosed easily based on pure histologic findings with or without immunohistochemical examination. Furthermore, molecular-genetic testing can be utilized to assist in arriving at an accurate diagnosis. In this review, we presented the most current knowledge concerning molecular-genetic aspects of renal epithelial neoplasms, which potentially can be used in daily diagnostic practice.

Papillary renal cell carcinoma with prominent spindle cell stroma - tumor mimicking mixed epithelial and stromal tumor of the kidney: Clinicopathologic, morphologic, immunohistochemical and molecular genetic analysis of 6 cases

Papillary renal cell carcinoma (PRCC) is currently a well-studied type of RCC. In addition to PRCC type 1, there are a number of other subtypes and variants of PRCCs which have been reported. We describe a series of 6 PRCCs with papillary, micropapillary and/or tubulopapillary architecture and prominent spindle cell stroma, resembling stroma in mixed epithelial and stromal tumor of the kidney (MESTK) or sarcomatoid RCC. Clinicopathologic, morphologic, immunohistochemical and molecular features were analyzed. All patients were males with an age range of 44-98 years (mean 65.3, median 65.5 years). Tumor size ranged from 2.4-11.4 cm (mean 5.8, median 4.5 cm). Follow-up data were available for 4 patients, ranging from 3 to 96 months (mean 42.75, median 36 months). Epithelial cells were mostly cylindrical with eosinophilic cytoplasm, showing nuclear grade 2 and 3 (ISUP/WHO). In all cases, loose to compact prominent stroma composed of spindle cells, without malignant mesenchymal heterologous elements was detected. No atypical mitoses were found, while typical mitoses were rare in both epithelial and stromal components. Epithelial cells were positive for CK7, AMACR, and vimentin in all cases, while negative for TFE3, HMB45, desmin, CD34, and actin. The stroma was positive for vimentin, actin and focally for CD34, while negative for CK7, AMACR, TFE3, HMB45, and desmin. Estrogen and progesterone receptors were completely negative. FH and SDHB expression was retained in all analyzable cases. Proliferative index was barely detectable in stromal component and low in epithelial component, ranging 0 to 5% positive stained cells/high power field. Copy number variation was variable with no distinct pattern. No mutations in CDKN2A, BAP1, MET were detected. PRCC with MESTK-like features is a distinct variant of PRCC mimicking MESTK. Our findings add to the body of literature on ever expanding variants of PRCCs. Both epithelial and stromal components lacked true Müllerian features, which was also proven by immunohistochemistry.

Reactivity of CK7 across the spectrum of renal cell carcinomas with clear cells

AIMS

Current available data on cytokeratin 7 (CK7) immunostaining pattern in the clear cell renal cell carcinoma (RCC) spectrum is conflicting. The aim of this study was to assess CK7 immunoreactivity within the spectrum of clear cell renal neoplasms, including clear cell RCC, multicystic renal neoplasm of low malignant potential and clear cell papillary RCC-like tumours.

METHODS AND RESULTS

We analysed two clones of CK7 and two tumour blocks for a total of 75 cases divided into five distinct groups: (i) low-grade clear cell RCC, (ii) high-grade clear cell RCC, (iii) multicystic renal neoplasm of low malignant potential, (iv) clear cell RCC with cystic changes and (v) clear cell papillary RCC-like tumours. We found the highest CK7 reactivity in low-grade clear cell RCC, multicystic renal neoplasm of low malignant potential and clear cell papillary RCC-like groups, ranging from 60% to 93%.

CONCLUSIONS

Our findings show that CK7 immunoreactivity in clear cell RCC is variable, and the extent of staining depends on the grade and architectural growth patterns of the tumours.

Clear Cell Papillary Renal Cell Carcinoma

Clear cell papillary renal cell carcinoma (ccpRCC) is a recently recognized entity and represents the fourth most common variant of renal cell carcinoma (RCC). It has unique morphologic and immunohistochemical features and demonstrates an indolent clinical behavior. Microscopically, it may mimic other RCCs with clear cell features, such as clear cell RCC, translocation RCC, and papillary RCC with clear cell changes. A high index of suspicion is required to keep ccpRCC in the differential diagnosis of RCCs with features of clear cell and/or papillary architecture. In equivocal cases, immunohistochemistry is generally sufficient to substantiate the diagnosis of ccpRCC. In this review, we discuss the clinical, gross, and histopathologic features, immunohistochemical and genetic profiling, and prognosis of ccpRCC.

Papillary pattern in clear cell renal cell carcinoma: Clinicopathologic, morphologic, immunohistochemical and molecular genetic analysis of 23 cases

Clear cell renal cell carcinoma (ccRCC), the most common histologic subtype of RCCs, demonstrates a wide spectrum of morphologic features (i.e., low-grade spindle cell, syncytial giant cells, and mucin-producing cells). However, papillary growth pattern in ccRCCs is rather a rare finding, which can present challenges in differential diagnostic work up. The aim of this study was to investigate ccRCCs with predominant papillary features from morphologic, immunohistochemical and molecular genetic perspectives. 23 clear cell renal cell carcinomas with papillary architecture were selected. Tumors were evaluated morphologically, immunohistochemically, and molecularly by next-generation sequencing (NGS). The diagnosis of MiT family translocation RCC was excluded by TFE3 immunohistochemistry. Mean age of patients was 65.2 years (range 42-81 years), and 19/23 were male. Tumor size ranged from 1.6 to 12.8 cm (median 6.5 cm). At a median follow-up of 2.5 years (range 1.5-9 years), 2 patients (8.7%) died of disease, 2 developed metastasis. Areas of papillary pattern accounted for approximately 40-100% of the tumor. CK7 was negative in non-papillary areas in majority of cases (20/23, 87%), and was only focally positive in 3/23 cases (13%). In papillary areas, AMACR was positive/focally positive in 17/23 (73.9%) cases and in the non-papillary areas it was positive/focally positive in 22/23 (95.6%) cases. CAIX was mainly negative in both non-papillary and papillary areas (15/23 [65%] and 16/23 [69.5%], respectively). Molecular analysis of 15 analyzable cases revealed the most frequently mutated gene to be VHL (in 9 cases), followed by PRBM1 (in 2 cases) and 29 other different mutations in various genes. Papillary growth pattern in ccRCC is not an uncommon situation. Papillary RCC with clear cells and MiT family (TFE3) translocation RCCs are the major differential diagnostic considerations in such scenarios. Our NGS molecular analysis supported classifying such tumors as a morphologic variant of ccRCC.

Integrated analysis of long noncoding RNA associated-competing endogenous RNA as prognostic biomarkers in clear cell renal carcinoma

Clear cell renal cell carcinoma (ccRCC) is one of the most common malignant carcinomas and its molecular mechanisms remain unclear. Long noncoding RNA (lncRNA) could bind sites of miRNA which affect the expression of mRNA according to the competing endogenous (ceRNA) theory. The aim of the present study was to construct a ceRNA network and to identify key lncRNA to predict survival prognosis. We identified differentially expressed mRNA, lncRNA and miRNA between tumor tissues and normal tissues from The Cancer Genome Atlas database. Then, using bioinformatics tools, we explored the connection of 89 lncRNA, 10 miRNA and 22 mRNA, and we constructed the ceRNA network. Furthermore, we analyzed the functions and pathways of 22 differentially expressed mRNA. Then, univariate and multivariate Cox regression analyses of these 89 lncRNA and overall survival were explored. Nine lncRNA were finally screened out in the training group. The patients were divided into high‐risk and low‐risk groups according to the 9 lncRNA and low‐risk scores having better clinical overall survival (P < .01). Furthermore, the receiver operating characteristic curve demonstrates the predicted role of the 9 lncRNA. The 9‐lncRNA signature was successfully proved in the testing group and the entire group. Finally, multivariate Cox regression analysis and stratification analysis further proved that the 9‐lncRNA signature was an independent factor to predict survival. In summary, the present study provides a deeper understanding of the lncRNA‐related ceRNA network in ccRCC and suggests that the 9‐lncRNA signature could serve as an independent biomarker to predict survival in ccRCC patients.

Bilateral renal cell carcinoma with leiomyomatous stroma: A rare entity diagnosed synchronously and treated surgically in a staged fashion

Renal cell carcinoma (RCC) accounts for approximately 3% of adult malignancies and 90-95% of kidney neoplasms. Renal cell carcinoma with leiomyomatous stroma (RCCLS) is an extremely rare histopathological entity based on available literature data. Herein, we report a 31-year-old male with incidentally detected synchronous bilateral renal masses who was eventually found to harbor RCCLS after being operated sequentially via nephron-sparing surgery.