Leiomyomatous Stroma Research Articles

Current Knowledge and Prospects for Renal Hemangioblastoma and Renal Cell Carcinoma with Hemangioblastoma-like Features.

Tumors exhibiting histopathological findings similar to those of hemangioblastoma of the central nervous system (CNS-HB) rarely develop in the kidneys. Currently, renal hemangioblastoma (RHB) is considered analogous to CNS-HB; however, they differ in gross appearance, as well as immunohistochemical and molecular findings. In contrast, some renal cell carcinomas reportedly comprise distinct, clear cell renal cell carcinoma (CCRCC)- and hemangioblastoma (HB)-like areas. Initially, renal cell carcinomas with HB-like features (RCC-HBs) were considered a morphological variant of CCRCC owing to their diverse histological findings. However, the immunohistochemical and molecular findings of RCC-HBs suggest that RCC-HB is distinct from CCRCC. Additionally, one of the RCC-HBs had a focal leiomyomatous stroma and TSC2 variant, suggesting that RCC-HB and RCC with fibromyomatous stroma (RCC-FMS) might belong to the same disease entity. Therefore, we comprehensively reviewed the clinical, pathological, and molecular features of RHB, RCC-HB, and the related tumors and discussed the similarities, differences, and relationships between them. We believe that our review would serve as a foundation for further investigation on elucidating the relationship between CNS-HB, RHB, RCC-HB, and RCC-FMS.

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.

Tuberous Sclerosis Complex Associated Renal Cell Carcinoma with Leiomyomatous Stroma

This case report is about an unusual subtype of renal cell carcinoma with distinct morphological pattern in a 24-year-old female patient with tuberous sclerosis complex. She presented with pain in the left flank and an Magnetic Resonance Imaging (MRI) upper abdomen showed a solid cystic lesion in the interpolar region of left kidney, measuring 2.8×2.8×2.8 cm. She underwent partial nephrectomy which revealed a solid cystic tumour. Microscopically, the tumour was composed of long branching tubules lined by cells with voluminous clear/ vacuolated cytoplasm. A prominent fibromyomatous stroma was seen focally, separating the tumour into nodular aggregates. Tumour cells were positive for Cytokeratin 7 (CK7) on immunohistochemical study. These features were consistent with renal cell carcinoma with leiomyomatous stroma. Genetic study showed a heterozygous nonsense variation in Tuberous Sclerosis 1 (TSC1), gene, diagnostic of tuberous sclerosis. This report exemplifies the pivotal role pathologists play in the initial identification of certain hereditary cancer syndrome. The distinct morphology and immunohistochemical profile of the tumour is described.

Are Renal Cell Carcinoma with Fibromyomatous Stroma (RCC-FMS) and Thyroid-like Follicular Carcinoma of the Kidney (TLFCK) Really Independent Variants?

Renal cell carcinoma with fibromyomatous stroma (RCC-FMS) is a recent provisional entity already recognised in the 2016 WHO Classification of Cancer of the Urinary Tract and Male Genital Organs 4th Edition as renal cell carcinoma with (angio)leiomyomatous stroma, histologically defined as a tumour characterised by clear cells intertwined in a conspicuous vascular stroma. In the casuistry taken into consideration, another proposed variant, thyroid-like follicular carcinoma of the kidney (TLFCK), endowed with a morphology mimicking thyroid parenchyma, was examined. The aim of this work was to parse the theoretical system, experimental data and diagnostic impact of these new entities proposed in the field of renal neoplasms. An analysis of 120 cases of kidney tumours from the Department of Surgical, Medical, Molecular and Critical Area at the University of Pisa was run. Subsequently, all samples were reassessed by two pathologists with expertise in uropathology, whose revaluation provided a histomorphological study combined with subsequent and coherent immunohistochemical analyses of CK7, CD10, CAIX, CK34betaE12, CD117, vimentin, TTF-1 and thyroglobulin. These analyses were performed using the Ventana Benchmark Automated Staining System (Ventana Medical Systems, Tucson, AZ, USA) and Ventana reagents. On the one hand, the data, thus brought to light, did not show an immunohistochemical profile consistent with that proposed for RCC-FMS. However, it should be emphasised that the morphological background also unearthed a poor specificity for RCC-FMS. This was specifically due to a stromal component which was, in any case, evident, although characterised by a wide range of presentation, in clear cell renal cell carcinoma (ccRCC). This latter is, indeed, the reference background for this theorised variant. On the other hand, a thyroid-like pattern was highlighted in 11 cases, more specifically in 10 ccRCCs and in one oncocytoma, presenting itself as a type of neoplastic appearance rather than as the peculiar morphological pattern of a standalone cancer. In the light of these results, RCC-FMS and TLFCK appear to be more appropriately variants of already categorised neoplastic entities rather than new independent neoplasias.

Rare renal cell carcinoma with haemangioblastoma-like features and leiomyomatous stroma: report of a unique case with TSC2 and SETD2 variations

BackgroundRenal cell carcinoma (RCC) with haemangioblastoma-like characteristics is a type of RCC reported in recent years. RCC with (angio) leiomyomatous stroma (RCCLMS) was included as a provisional entity of the 2016 World Health Organization (WHO) classification. RCC with haemangioblastoma-like characteristics and leiomyomatous stroma is extremely rare. This is the first report of a rare tumour harbouring TSC2 and SETD2 variations.Case presentationThe patient was a 38-year-old woman who presented with discomfort in the area of her right kidney. Ultrasound and enhanced CT showed a right renal mass, and clear cell renal cell carcinoma (CCRCC) was suspected; hence, robot-assisted laparoscopic nephron-sparing partial nephrectomy was performed. Gross examination revealed a well-circumscribed tumour measuring 2.0 cm × 1 cm × 0.7 cm under the renal capsule adjacent to the stripping edge that was greyish yellow and greyish red in colour. Histologic examination showed that the tumour consisted of three different structures: a CCRCC-like region, a haemangioblastoma-like region, and a focal leiomyomatous stroma component. Based on immunohistochemistry, the CCRCC-like region was diffusely strongly positive for AE1/AE3, vimentin, CAIX, PAX8, PAX2, CK7, and CAM5.2, partly positive for HNF1α, and negative for CD10, α-inhibin, NSE, S-100, CD34, and TFE3. The haemangioblastoma-like area was diffusely positive for vimentin, CAIX; partly positive for PAX8, PAX2, α-inhibin, and S-100; mostly positive for NSE; and slightly positive for HNF1α; the CD34 staining highlighted the complex capillary network. The Ki67 index was approximately 1–2% in the two above areas, and the leiomyomatous stroma was strongly positive for SMA. The whole-exon sequencing (WES) showed TSC2 and SETD2 variations. There was no progression after 18 months of follow-up.ConclusionWe report for the first time a unique case of RCC with haemangioblastoma-like features and leiomyomatous stroma accompanied by rare molecular abnormalities. Whether this is a new tumour entity or a variant of clear cell carcinoma remains to be determined. The biological behaviour and clinical characteristics need to be further examined.

Renal Cell Carcinoma With Fibromyomatous Stroma-The Whole Story.

Renal cell carcinoma (RCC) with fibromyomatous stroma (FMS) was included as an "emerging/provisional" entity in the 2016 World Health Organization (WHO) classification as a "RCC with (angio) leiomyomatous stroma." It has been debated whether RCCFMS represents a separate entity or a group of RCCs with overlapping morphologies. Accordingly, various names have been used to refer to the RCCs that exhibited clear cells and prominent smooth muscle and fibromatous stroma. Recent studies have demonstrated that RCCFMS indeed represents a distinct entity with subtle but distinguishable features that can be separated from other RCCs that exhibit clear cells, as well as tubulopapillary morphology and smooth muscle/fibromatous stroma, such as clear cell RCC and clear cell papillary RCC. Microscopically, the epithelial component forms tumor nodules composed of elongated and frequently branching tubules, lined by clear or mildly eosinophilic cells containing voluminous cytoplasm. Focal papillary morphology is also frequently present. Diffuse CK7 positivity is typical and is required for the diagnosis. Molecular analysis of these tumors demonstrated recurrent mutations involving the TSC/mTOR pathway. A subset of tumors with similar morphology has shown mutations involving ELOC (previously referred to as TCEB1), typically associated with monosomy 8. Finally, in addition to the more common RCCFMS that are sporadic, essentially identical tumors have been found in patients with tuberous sclerosis complex, suggesting the existence of hereditary and sporadic counterparts of this tumor. It is currently debated whether TSC/mTOR and ELOC mutated RCCFMS should be grouped together, based on their shared and overlapping morphology and common CK7 reactivity, despite the differing molecular alterations. This review outlines evidence supporting the recognition of RCCFMS as a novel subtype of RCC with morphologic, immunohistochemical, and molecular characteristics distinct from clear cell RCC and clear cell papillary RCC.

Renal cell carcinoma with leiomyomatous stroma: A case report and a review of the literature of a provisional entity distinct from conventional renal cell carcinoma

Renal Cell Carcinoma with Leiomyomatous Stroma (RCCLMS) is a rare renal cancer with indolent behavior and favorable prognosis. We present a case of rare renal cell carcinoma with leiomyomatous stroma in a 49-year-old male, with an incidental finding of a 1.6 cm renal nodule on MRI scan. The patient underwent partial nephrectomy of the left kidney and subsequent histological examination showed an epithelial tumor composed of clear cell cytoplasm with low grade nuclear features, surrounded by an abundant smooth muscle stroma composed of fascicles of spindle cells. Immunohistochemistry revealed the positive reaction of tumor cells for CK7, CD10, CAIX, vimentin and desmin; negative for AMACR. Molecular testing via FISH study shows lack of 3p deletion. Final diagnosis of RCCLMS was made. The aim of this case report is to highlight the importance of awareness of this disease as well as to differentiate RCCLMS from other renal cancers with less favorable prognosis and higher degree of malignancy like clear cell renal cell carcinoma. Keywords: renal cell carcinoma; leiomyomatous stroma; kidney.

Carcinome rénal à stroma léiomyomateux avec métaplasie osseuse chez un patient porteur d’une sclérose tubéreuse de Bourneville

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 (TSC2gene 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.

Renal Cell Carcinoma in Tuberous Sclerosis Complex

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder in which renal manifestations are prominent. There are three major renal lesions in TSC: angiomyolipomas, cysts, and renal cell carcinoma (RCC). Major recent advances have revolutionized our understanding of TSC-associated RCC, including two series that together include more than 100 TSC-RCC cases, demonstrating a mean age at onset of about 36 years, tumors in children as young as 7, and a striking 2:1 female predominance. These series also provide the first detailed understanding of the pathologic features of these distinctive tumors, which include chromophobe-like features and eosinophilia, with some of the tumors unclassified. This pathologic heterogeneity is distinctive and reminiscent of the pathologic heterogeneity in Birt–Hogg–Dube-associated RCC, which also includes chromophobe-like tumors. Additional advances include the identification of sporadic counterpart tumors that carry somatic TSC1/TSC2/mTOR mutations. These include unclassified eosinophilic tumors, eosinophilic solid cystic RCC (ESC-RCC), and RCC with leiomyomatous stroma (RCCLMS). A variety of epithelial renal neoplasms have been identified both in patients with tuberous sclerosis complex (TSC) and in the nonsyndromic setting associated with somatic mutations in the TSC1 and TSC2 genes. Interestingly, whether tumors are related to a germline or somatic TSC1/2 mutation, these tumors often display similar morphologic and immunophenotypic features. Finally, recent work has identified molecular links between TSC and BHD-associated tumors, involving the TFEB/TFE3 transcription factors.

Renal cell carcinoma with leiomyomatous stroma in tuberous sclerosis complex: a distinct entity.

Renal cell carcinoma with leiomyomatous stroma (RCCLS) is an emerging entity frequently associated with tuberous sclerosis complex (TSC). We described herein a series of RCCLS in TSC patients at pathological and cytogenetic levels. Three male patients with TSC and RCCLS were identified between 2000 and 2019 at the University Hospital of Rennes. Histologically, the architecture was tubulo-papillary with thick bundles of smooth muscle cells. The tumor cells showed clear cytoplasm with eosinophilic globules. The immunohistochemical profile was identical with an intense positivity of CK7, CAIX, and CD10 and a heterogeneous positivity of CK20. SDHB was low but positive and TFE3 was not expressed. Comparative genomic hybridization (CGH) did not show any quantitative chromosome abnormality. No recurrence was observed with a median follow-up of 4 years. RCCLS in TSC patients has morphological, immunohistochemical, and cytogenetic distinct features that could constitute a distinct entity and a sentinel manifestation for the diagnosis of TSC.

Clear Renal Cell Carcinoma with Angioleiomyomatous Stroma in a Noninherited Renal Cancer Syndrome

Renal cell carcinoma (RCC) comprises only 3% of adult cancer cases. In most cases, patient is asymptomatic and the tumor mass is incidentally detected during radiological imaging for other medical conditions. Only one-third of patients with RCC present with hematuria, palpable tumor mass, or flank pain. Most of the cases of RCC are with clear or papillary cells, but a small subset of cases have demonstrated clear cell RCC with leiomyomatous stroma. The World Health Organization classification of tumors of the urinary system and male genital organs 2016 and the International Society Urological Pathology 2012 Vancouver classification have identified RCC with leiomyomatous stroma (RCCLMS) as an emerging entity of RCC. RCCLMS has been seen with inherited renal cancer syndromes such as tuberous sclerosis complex and von Hippel-Lindau disease. Here, we present a rare case of RCC with morphological and histopathological findings of the RCCLMS subset but showed noninherited mutational traits.

"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.

Genetic Underpinnings of Renal Cell Carcinoma With Leiomyomatous Stroma.

Renal cell carcinoma (RCC) with leiomyomatous stroma is a provisional category of RCC in the 2016 World Health Organization Classification of Tumors of the Urinary System. Microscopic examination of hematoxylin and eosin-stained sections reveals this entity to be well-circumscribed with tubulopapillary growth of cells with clear cytoplasm in a background of leiomyomatous stroma. Herein we describe the genetic features of 15 University of Chicago Medical Center archived cases with hematoxylin and eosin histology matching the provisional diagnosis. Immunohistochemical (IHC) stains revealed 1/15 of these tumors to be clear cell renal cell carcinoma (ccRCC) and 6/15 to be clear cell papillary renal cell carcinoma (ccpRCC), demonstrating the morphologic overlap with these discrete known entities. Interestingly 3/6 of the ccpRCCs had chromosome 18 gain suggesting there may be novel specific genetic changes in ccpRCC with leiomyomatous stroma. Of the remaining 8 tumors with IHC staining patterns that do not fit either ccRCC or ccpRCC only 3 of these had mutations in the recently described TCEB1 gene with concurrent monosomy of chromosome 8. These 3 cases had a somewhat unique IHC pattern that possibly could separate them from the 5 other non-ccRCC/non-ccpRCC cases. This descriptive study, although small, demonstrates the difficulty in applying the current World Health Organization provisional criteria at a single institution with suggestion of an immunohistochemcial panel that may assist in the diagnosis of TCEB1-mutated RCC with leiomyomatous stroma.

Renal cell carcinoma diagnosis and prognosis within the context of the WHO classification 2016

Histological classification of renal cell carcinoma (RCC) has become more and more important for clinical management, but relatively few is known regarding the swiftness with which the 2016 World Health Organization (WHO) classification of RCC was adopted in the daily routine diagnostics. To retrospectively review the histological diagnosis of RCC within the context of 2016 WHO classification followed by survival analysis. Retrospective register based analysis of RCC diagnosis between 1998 and 2017 and survival analysis. 1440 RCC cases were registered between 1998 and 1917. According to 2016 WHO classification, 77.7% clear cell RCC and 22.3% non-clear cell RCC were diagnosed. Atotal of 37rare subtypes were recorded, among those 1% MiT family translocation RCC, 0.35% acquired cystic disease-associated RCC, 0.35% multilocular cystic renal neoplasm of low malignant potential, 0.35% collecting duct carcinoma, 0.3% mucinous tubular and spindle cell carcinoma, 0.1% clear cell papillary RCC and 0.1% RCC with (angio)leiomyomatous stroma. Cox regression analysis showed significant different overall survival and progression-free survival between the histological subtypes. The complexity of the 2016 WHO classification of RCC put high demands on histopathological diagnostics. At University Medicine Center Rostock morphological distinct RCC entities have been mostly diagnosed by conventional means via hematoxillin and eosin stained slides, but beyond immunohistochemistry additionally molecular techniques were established. The histologic subtyping of RCC according to 2016 WHO classification has prognostic significance and might have predictive significance for unique therapeutic approaches.

58. Renal cell carcinoma with leiomyomatous stroma – A new provisional entity

Background: Renal cell carcinoma (RCC) with leiomyomatous stroma (RCCLS) is a recently recognised entity with indolent biological behaviour. Prominent smooth muscle in the stroma, so called leiomyomatous stroma, is an unusual finding in renal cell carcinomas (RCCs). It has been reported in clear cell (tubulo) papillary RCCs, renal angiomyoadenomatous tumours (RAT), and clear cell RCCs.

Renal Cell Carcinoma With (Angio)Leiomyomatous Stroma in a Patient With TSC2 Mutation: A Case Report

Abstract We present the case of a 34-year-old woman with a TSC2 gene mutation diagnosed with 4 distinct renal cell carcinomas with (angio)leiomyomatous stroma and 2 concomitant angiomyolipomas of the left kidney. Histologically, the nodules, located in the renal cortex, were mostly encapsulated with an abundant smooth muscle stromal component, which delved into the central epithelial component of the tumor forming septations. The epithelial component was made up of elongated tubules, papillae, and acinar structures with clear to eosinophilic cytoplasm and apical snouts. Focal acinar structures were filled with hypereosinophilic material. The nuclei were basally located and supported by a delicate vascular network. Immunohistochemical studies revealed the tumor cells to express cytokeratin 7, CD10 variably, and carbonic anhydrase IX in an incomplete “cup-like” membranous pattern. The tumor cells did not express AMACR, TFE3, MART-1, or cathepsin K. This report describes a unique presentation of a rare entity and brings attention to an evolving diagnostic field. We discuss problems and controversy surrounding the diagnosis of renal cell carcinoma with (angio)leiomyomatous stroma, its relationship to clear cell papillary renal cell carcinoma and other tumors, and how it correlates with newly discovered genetic mutations.

Atypical tuberous sclerosis complex presenting as familial renal cell carcinoma with leiomyomatous stroma

We report an atypical tuberous sclerosis complex (TSC) phenotype presenting as familial multiple renal cell carcinomas (RCCs) with (angio)leiomyomatous stroma (RCCLS) (5/7 familial RCCs) on a background of multiple angiomyolipomas, hypopigmented skin macules, and absence of neurological anomalies. In the index case and three relatives, germline genetic testing identified a heterozygous TSC2 missense pathogenic variant [c.2714 G > A, (p.Arg905Gln)], a rare TSC‐associated alteration which has previously been associated with a milder TSC phenotype. Whole‐exome sequencing of five RCCs from the index case and one RCC from his mother demonstrated either unique tumour‐specific deleterious second hits in TSC2 or significant allelic imbalance at the TSC2 gene locus (5/6 RCCs). This study confirms the key tumourigenic role of tumour‐specific TSC2 second hits in TSC‐associated RCCs and supports the notion that RCCLS may be strongly related to abnormalities of the mTOR pathway.

Clear Cell Renal Cell Carcinoma

Renal cell carcinoma, clear cell type, forming a mass in the lower and mid portion of the kidney. Which is the most common subtype of renal cell carcinoma?a.Clear cellb.Papillaryc.Chromophobed.Unclassified Answer: a. Clear cell Clear cell renal cell carcinoma is the most common subtype of renal cell carcinoma (RCC), comprising 65% to 70% of RCC.1Moch H. Humphrey P.A. Ulbright T.M. Reuter V.E. WHO Classification of Tumours of the Urinary System and Male Genital Organs.4th ed. IARC Press, Lyon, France2016Google Scholar Papillary RCC comprises 15% to 20% and chromophobe RCC comprises 5% to 7% of RCC.1Moch H. Humphrey P.A. Ulbright T.M. Reuter V.E. WHO Classification of Tumours of the Urinary System and Male Genital Organs.4th ed. IARC Press, Lyon, France2016Google Scholar Other renal cell tumor subtypes include collecting duct carcinoma, renal medullary carcinoma, mucinous tubular and spindle cell carcinoma, RCC unclassified, papillary adenoma, and oncocytoma. Recently described renal cell tumors include multilocular cystic renal neoplasm of low malignant potential, MiT family translocation RCC, tubulocystic RCC, acquired cystic disease–associated RCC, clear cell papillary RCC, succinate dehydrogenase–deficient RCC, and hereditary leiomyomatosis and RCC-associated RCC. Additional emerging/provisional entities include oncocytic RCC occurring after neuroblastoma, thyroid-like follicular RCC, ALK rearrangement–associated RCC, and RCC with (angio)leiomyomatous stroma.1Moch H. Humphrey P.A. Ulbright T.M. Reuter V.E. WHO Classification of Tumours of the Urinary System and Male Genital Organs.4th ed. IARC Press, Lyon, France2016Google Scholar Although complex, the classification of renal cell tumors is important diagnostically and prognostically.

Renal Cell Carcinoma With Leiomyomatous Stroma: A Group of Tumors With Indistinguishable Histopathologic Features, But 2 Distinct Genetic Profiles: Next-Generation Sequencing Analysis of 6 Cases Negative for Aberrations Related to the VHL gene.

We have studied a cohort of renal cell carcinomas (RCCs) with smooth-muscle stroma (N=6), which lacked any of following genetic aberrations: mutations in the VHL-gene-coding sequence, loss of heterozygosity of chromosome 3p, or hypermethylation of VHL. Using targeted next-generation sequencing, no intronic VHL mutations or mutations in selected genes involved in angiogenesis and genes frequently mutated in clear cell RCC were identified. Tumors were also tested for the presence of hotspot mutations in the TCEB1 gene with negative results in all cases. We conclude that there exists a group of RCCs with abundant leiomyomatous stroma, where the epithelial component is indistinguishable from conventional clear cell RCC and distinct from clear cell (tubulo-) papillary RCC and that these tumors lack aberrations related to the function of the VHL gene, mutations in genes involved in angiogenesis, and hotspot mutations in the TCEB1 gene.

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.