Mesoscale DNA feature in antibody-coding sequence facilitates somatic hypermutation.

Somatic hypermutation (SHM), initiated by activation-induced cytidine deaminase (AID), generates mutations in the antibody-coding sequence to allow affinity maturation. Why these mutations intrinsically focus on the three nonconsecutive complementarity-determining regions (CDRs) remains enigmatic. Here, we found that predisposition mutagenesis depends on the single-strand (ss) DNA substrate flexibility determined by the mesoscale sequence surrounding AID deaminase motifs. Mesoscale DNA sequences containing flexible pyrimidine-pyrimidine bases bind effectively to the positively charged surface patches of AID, resulting in preferential deamination activities. The CDR hypermutability is mimicable in in vitro deaminase assays and is evolutionarily conserved among species using SHM as a major diversification strategy. We demonstrated that mesoscale sequence alterations tune the in vivo mutability and promote mutations in an otherwise cold region in mice. Our results show a non-coding role of antibody-coding sequence in directing hypermutation, paving the way for the synthetic design of humanized animal models for optimal antibody discovery and explaining the AID mutagenesis pattern in lymphoma.

Impact of preoperative transcatheter arterial chemoembolization (TACE) on postoperative long-term survival in patients with nonsmall hepatocellular carcinoma: a propensity score matching analysis.

BACKGROUND: The purpose of this propensity score matching (PSM) analysis was to compare the effects of preoperative transcatheter arterial chemoembolization (TACE) and non-TACE on the long-term survival of patients who undergo radical hepatectomy. METHODS: PSM analysis was performed for 387 patients with hepatocellular carcinoma (HCC) (single > 3 cm or multiple) who underwent radical resection of HCC at our centre from January 2011 to June 2018. The patients were allocated to a preoperative TACE group (n = 77) and a non-TACE group (n = 310). The main outcome measures were progression-free survival (PFS) and overall survival (OS) since the treatment date. RESULTS: After PSM, 67 patients were included in each of the TACE and non-TACE groups. The median PFS times in the preoperative TACE and non-TACE groups were 24.0 and 11.3 months, respectively (p = 0.0117). The median OS times in the preoperative TACE and non-TACE groups were 41.5 and 29.0 months, respectively (p = 0.0114). Multivariate Cox proportional hazard regression analysis revealed that preoperative TACE (hazard ratio, 1.733; 95% CI, 1.168-2.570) and tumour thrombosis (hazard ratio, 0.323; 95% CI, 0.141-0.742) were independent risk factors significantly associated with OS. CONCLUSIONS: Preoperative TACE is related to improving PFS and OS after resection of HCC. Preoperative TACE and tumour thrombus volume were also found to be independent risk factors associated with OS.

Extended lymphadenectomy based on the TRIANGLE for pancreatic head cancer: a single-center experience.

BACKGROUND: This study was to compare the safety and efficacy of different lymphadenectomy methods in patients with pancreatic head cancer undergoing pancreaticoduodenectomy (PD). MATERIAL AND METHODS: A total of 150 patients were included in this study. Patients were divided into Group A (n = 79), Group B (n = 44), and Group C (n = 27) according to the different lymphadenectomy methods. The clinical endpoint was time to progression (TTP) and overall survival (OS). Postoperative complications of different lymphadenectomy methods were compared respectively. TTP and OS of the three groups were compared by Kaplan-Meier curves. RESULTS: There were no significant differences between the three groups in operative time (P = 0.300), death in the hospital (P = 0.253), postoperative hemorrhage (P = 0.863), postoperative pancreatic fistula (POPF) B/C (P = 0.306), bile leakage (P = 0.215), intestinal fistula (P = 0.177), lymphatic leakage (P = 0.267), delayed gastric emptying [(DGE) (P = 0.283)], ICU stay (P = 0.506), and postoperative hospital stay [(PHS) (P = 0.810)]. Median TTP in Groups B and C was significantly longer than in Group A (log-rank test, A vs B: P = 0.0005, A vs C: P = 0.0001). Median OS between the three groups has no statistical difference (P = 0.1546). CONCLUSIONS: Extended lymphadenectomy methods based on the TRIANGLE do not increase perioperative complications significantly and can effectively delay tumor progression in patients with pancreatic head cancer.

A novel nomogram based on the number of positive lymph nodes can predict the overall survival of patients with pancreatic head cancer after radical surgery.

BACKGROUND: This study aimed to construct a novel nomogram based on the number of positive lymph nodes to predict the overall survival of patients with pancreatic head cancer after radical surgery. MATERIALS AND METHODS: 2271 and 973 patients in the SEER Database were included in the development set and validation set, respectively. The primary clinical endpoint was OS (overall survival). Univariate and multivariate Cox regression analyses were used to screen independent risk factors of OS, and then independent risk factors were used to construct a novel nomogram. The C-index, calibration curves, and decision analysis curves were used to evaluate the predictive power of the nomogram in the development and validation sets. RESULTS: After multivariate Cox regression analysis, the independent risk factors for OS included age, tumor extent, chemotherapy, tumor size, LN (lymph nodes) examined, and LN positive. A nomogram was constructed by using independent risk factors for OS. The C-index of the nomogram for OS was 0.652 [(95% confidence interval (CI): 0.639-0.666)] and 0.661 (95%CI: 0.641-0.680) in the development and validation sets, respectively. The calibration curves and decision analysis curves proved that the nomogram had good predictive ability. CONCLUSIONS: The nomogram based on the number of positive LN can effectively predict the overall survival of patients with pancreatic head cancer after surgery.

Characterization and designing of an SAM riboswitch to establish a high-throughput screening platform for SAM overproduction in Saccharomyces cerevisiae.

S-adenosyl- l-methionine (SAM) is a high-value compound widely used in the treatment of various diseases. SAM can be produced through fermentation, but further enhancing the microbial production of SAM requires novel high-throughput screening methods for rapid detection and screening of mutant libraries. In this work, an SAM-OFF riboswitch capable of responding to the SAM concentration was obtained and a high-throughput platform for screening SAM overproducers was established. SAM synthase was engineered by semirational design and directed evolution, which resulted in the SAM2S203F,W164R,T251S,Y285F,S365R mutant with almost twice higher catalytic activity than the parental enzyme. The best mutant was then introduced into Saccharomyces cerevisiae BY4741, and the resulting strain BSM8 produced a sevenfold higher SAM titer in shake-flask fermentation, reaching 1.25 g L-1 . This work provides a reference for designing biosensors to dynamically detect metabolite concentrations for high-throughput screening and the construction of effective microbial cell factories.

An innovative surgical approach: suture fixation of the levonorgestrel-releasing intrauterine system in the treatment of adenomyosis.

BACKGROUND: Placement of a levonorgestrel-releasing intrauterine system (LNG-IUS) is an effective treatment for adenomyosis, especially for patients who have severe dysmenorrhea symptoms but a strong desire to preserve fertility. Nonetheless, for patients with adenomyosis accompanied by an enlarged uterus, expulsion of the ring is a troublesome problem. In this study, we sewed and fixed the LNG-IUS in the uterus, which provides a good solution to this problem. METHODS: In this prospective case series approved by the Ethics Committee of Hangzhou Women's Hospital, 12 patients with adenomyosis were successfully enrolled after providing informed consent, and all patients underwent long-term postoperative follow-up. RESULTS: Twelve patients with adenomyosis underwent suture fixation with an LNG-IUS, and during the long-term postoperative follow-up, every patient experienced complete remission of their symptoms: a significant decrease in menstrual flow, relief of dysmenorrhea, and improvement in quality of life. Only one person reported expulsion a year later. CONCLUSION: In patients with adenomyosis suffering from dysmenorrhea or excessive menstrual blood loss, suture fixation of an LNG-IUS using the hysteroscopic cold knife surgery system is a minimally invasive and effective alternative treatment for adenomyosis and decreases the risk of LNG-IUS expulsion.

Expression of SET domain bifurcated histone lysine methyltransferase 1 and its clinical prognostic significance in hepatocellular carcinoma.

BACKGROUND: To detect the expression of histone methyltransferase SETDB1 in hepatocellular carcinoma, and to analyze the relationship between SETDB1 expression and tumor size, microvascular invasion, pTNM stage, gender, age, tumor number, tumor differentiation, and other clinicopathological characteristics. METHODS: Immunohistochemical method was used to detect the expression of SETDB1 proteins in liver cancer tissues and adjacent tissues of 100 cases. The qRT-PCR method was used to detect the expression of SETDB1 mRNA in hepatocellular carcinoma and adjacent tissues of 64 cases. RESULTS: The expression of SETDB1 protein and mRNA in hepatocellular carcinoma was higher than that of adjacent normal liver tissue (p < 0.05). High protein expression of SETDB1 was associated with tumor size, MVI presence, and pTNM stage (p < 0.05). Univariate analysis revealed that the tumor size, tumor differentiation, MVI grade, and pTNM stage were correlated with DFS, while tumor size, MVI grade, pTNM stage, and SETDB1 protein expression were correlated with OS. Multivariate analysis showed that the combination of MVI grade and pTNM stage has statistical significance in predicting prognosis, while SETDB1 protein expression was not significant prognosis factor. CONCLUSIONS: SETDB1 has a certain role in HCC progression and may act as a prognostic predictor concerning the survival of HCC patients.

RNA m6A methylation regulators in ovarian cancer.

N6-methyladenosine (m6A) is the most abundant RNA modification of mammalian mRNAs and plays a vital role in many diseases, especially tumours. In recent years, m6A has become the topic of intense discussion in epigenetics. M6A modification is dynamically regulated by methyltransferases, demethylases and RNA-binding proteins. Ovarian cancer (OC) is a common but highly fatal malignancy in female. Increasing evidence shows that changes in m6A levels and the dysregulation of m6A regulators are associated with the occurrence, development or prognosis of OC. In this review, the latest studies on m6A and its regulators in OC have been summarized, and we focus on the key role of m6A modification in the development and progression of OC. Additionally, we also discuss the potential use of m6A modification and its regulators in the diagnosis and treatment of OC.

Evidence-based Guideline for Therapeutic Drug Monitoring of Vancomycin: 2020 Update by the Division of Therapeutic Drug Monitoring, Chinese Pharmacological Society.

BACKGROUND: Clinical practice guidelines or recommendations often require timely and regular updating as new evidence emerges, because this can alter the risk-benefit trade-off. The scientific process of developing and updating guidelines accompanied by adequate implementation can improve outcomes. To promote better management of patients receiving vancomycin therapy, we updated the guideline for the therapeutic drug monitoring (TDM) of vancomycin published in 2015. METHODS: Our updated recommendations complied with standards for developing trustworthy guidelines, including timeliness and rigor of the updating process, as well as the use of the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. We also followed the methodology handbook published by the National Institute for Health and Clinical Excellence and the Spanish National Health System. RESULTS: We partially updated the 2015 guideline. Apart from adults, the updated guideline also focuses on pediatric patients and neonates requiring intravenous vancomycin therapy. The guideline recommendations involve a broadened range of patients requiring TDM, modified index of TDM (both 24-hour area under the curve and trough concentration), addition regarding the necessity and timing of repeated TDM, and initial dose for specific subpopulations. Overall, 1 recommendation was deleted and 3 recommendations were modified. Eleven new recommendations were added, and no recommendation was made for 2 clinical questions. CONCLUSIONS: We updated an evidence-based guideline regarding the TDM of vancomycin using a rigorous and multidisciplinary approach. The updated guideline provides more comprehensive recommendations to inform rational and optimized vancomycin use and is thus of greater applicability.

TFE3 rearranged epithelioid hemangioendothelioma of bone: A clinicopathological, immunohistochemical and molecular study of two cases.

Epithelioid hemangioendothelioma (EHE) is a rare malignant angiocentric vascular neoplasm. Around 90% of classic EHE has a t(1;3)(p36;q25) that results in a WWTR1-CAMTA1 fusion gene, a histologically distinctive subset of EHE has been recently shown to have a t(10;14)(p13;q42)that results in a different fusion gene, YAP1-TFE3. Twenty-one cases of TFE3 Rearranged Epithelioid Hemangioendothelioma have been reported in the literature, and only two cases occurred in bone. In the report, we report additional two cases occurred in the femur and skull and review the related literature.

Downregulation and subcellular distribution of HER2 involved in MDA-MB-453 breast cancer cell apoptosis induced by lapatinib/celastrol combination.

PURPOSE: To investigate the effect and related molecular mechanisms of lapatinib/celastrol combination or single-agent treatment in HER2/neu-overexpressing MDA-MB-453 breast cancer cells. METHODS: The effects of treatment with lapatinib, celastrol or their combination on cell growth were determined using MTT assay. Drug synergy was determined using the combination index (CI) methods derived from Chou-Talalay equations using CalcuSyn software. Apoptotic morphology was observed by fluorescence microscope with Hoechst 33258 staining. Changes of apoptotic and growth pathways-related proteins were analysed by Western blot. The expression of HER2 of cell surface was performed by flow cytometry. Subcellular distribution of HER2 was observed by immunofluorescence study. RESULTS: Combination celastrol and lapatinib produced strong synergy in growth inhibition and apoptosis in comparison to single-agent treatment in HER2/neu-overexpressing MDA-MB-453 cells. Interestingly, compared with celastrol treatment alone, lapatinib/celastrol combination induced more HER2 membrane protein downregulation and ectopic to cytoplasm and nucleus in MDA-MB-453 cells. CONCLUSION: The combination of celastrol and lapatinib could be used as a novel combination regimen which provides a strong anticancer synergy in the treatment of HER2/neu-overexpressing cancer cells.

Development and validation of a model for predicting who can benefit from multiple TACE in HCC patients.

This study was to develop and validate a model for predicting who can benefit from multiple transcatheter arterial chemoembolization (TACE) in hepatocellular carcinoma (HCC) patients.228 and 98 patients were included in the development and validation sets, respectively. The primary clinical endpoint was benefiting from consecutive multiple TACE treatments. Logistic regression analysis was used to screen the independent risk factors for the clinical endpoint. The independent risk factors were then used to construct the predictive model. The area under receiver operating characteristic (ROC) curves, calibration curves, and clinical decision curves were used to evaluate the predictive ability of the model.Multivariate Logistic regression analysis showed that complete envelope, hepatic lopes, tumor number, and alpha-fetoprotein (AFP) were independent risk factors for benefiting from multiple TACE in HCC patients. The area under the curve (AUC) of the model constructed by using independent risk factors in the development and validation sets was 0.843 (95% confidence interval [CI]: 0.784-0.902) and 0.828 (95%CI: 0.739-0.916), respectively. The calibration curves and clinical decision curves showed that the model had good predictive ability.The model established in this study has a good predictive effect on HCC patients who can benefit from multiple TACE.

Sarcomatoid carcinoma of the pancreas (Review).

Sarcomatoid carcinoma of the pancreas (SCP) is a rare and aggressive subtype of undifferentiated pancreatic ductal adenocarcinoma, with a generally poor prognosis and only sporadic cases reported worldwide. Histologically, the most notable feature of SCP is the presence of abundant of mesenchymatoid spindle tumor cells in the tumor, which lack glandular differentiation. Immunohistochemically, SCP is characterized by the expression of both mesenchymal and epithelial markers. With only a few reported cases, there is limited knowledge about its molecular and clinicopathological characteristics. Therefore, the present study performed a literature search to identify all relevant published studies. The present review provides an overview of the histogenesis, diagnosis, genetic features, prognosis and treatment of SCP, specifically focusing on the molecular alterations. Furthermore, a single-center experience is reported, which adds to the limited evidence available in the literature.

Fumarate Hydratase-Deficient Renal Cell Carcinoma With Predominant Tubulocystic Features Mimics Tubulocystic Renal Cell Carcinoma.

CONTEXT.­: Fumarate hydratase (FH)-deficient renal cell carcinoma (RCC) rarely exhibits a predominant tubulocystic architecture with few other components. RCC with pure tubules and cysts lined by eosinophilic tumor cells with prominent nucleoli would raise the diagnosis of tubulocystic RCC. It is important to differentiate the 2 entities because they lead to different outcomes. OBJECTIVE.­: To address the concern, a multicenter study was implemented to explore useful clinicopathologic features in differentiation between tubulocystic FH-deficient RCC and tubulocystic RCC. DESIGN.­: Clinical factors included age, sex, tumor size, and outcome. Morphologic factors included cell morphology, presence or absence of a nontubulocystic component, and stromal findings. Immunohistochemistry, fluorescence in situ hybridization, and next-generation sequencing were performed to explore the protein expression and molecular profiles of the 2 entities. RESULTS.­: We evaluated 6 patients with tubulocystic RCC and 10 patients with tubulocystic FH-deficient RCC. Tubulocystic RCC exhibited a small size (<4.0 cm, pT1a), low Ki-67 index (<5%), retained FH, and negative 2SC expression. Tubulocystic FH-deficient RCC had a relatively large size and a high Ki-67 index. Perinucleolar haloes, loss of FH, and 2SC positivity were always observed. Pure tubulocystic architecture was not observed in FH-deficient RCC, because focal nontubulocystic components can always be seen. CONCLUSIONS.­: We emphasized multiple sectioning to identify a nontubulocystic architecture to exclude tubulocystic RCC. Moreover, tumor size, FH/2SC staining, and the Ki-67 index can differentiate tubulocystic FH-deficient RCC from tubulocystic RCC. The diagnosis of tubulocystic RCC was not recommended in renal mass biopsy because of the limited tissues sampled.

Type-III-A structure of mycobacteria CRISPR-Csm complexes involving atypical crRNAs.

Tuberculosis (TB), a leading cause of mortality globally, is a chronic infectious disease caused by Mycobacterium tuberculosis that primarily infiltrates the lung. The mature crRNAs in M. tuberculosis transcribed from the Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) locus exhibit an atypical structure featured with 5' and 3' repeat tags at both ends of the intact crRNA, in contrast to typical Type-III-A crRNAs that possess 5' repeat tags and partial crRNA sequences. However, this structural peculiarity particularly concerning the specific binding characteristics of the 3' repeat end within the mature crRNA within the Csm complex, has not been comprehensively elucidated. Here, our Mycobacteria CRISPR-Csm complexes structure represents the largest Csm complex reported to date. It incorporates an atypical Type-III-A CRISPR RNA (crRNA) (46 nt) with 5' 8-nt and 3' 4-nt repeat sequences in the stoichiometry of Mycobacteria Csm1125364151. The PAM-independent single-stranded RNAs (ssRNAs) are the most suitable substrate for the Csm complex. The 3'-repeat end trimming of mature crRNA was not necessary for its cleavage activity in Type-III-A Csm complex. Our work broadens our understanding of the Type-III-A Csm complex and identifies another mature crRNA processing mechanism in the Type-III-A CRISPR-Cas system based on structural biology.

Primary Xp11 translocation PEComa of the testis with SFPQ⁃TFE3 rearrangement: a case report and review of the literature.

BACKGROUND: Perivascular epithelioid cell neoplasms (PEComas) are a family of mesenchymal tumors with features of both smooth muscle and melanocytic differentiation. A subset of PEComas demonstrate rearrangements involving the TFE3 (Xp11) locus. Xp11 translocation PEComa is a rare neoplasm with special clinicopathological features and a more aggressive behavior. We recently encountered a case of Xp11 translocation PEComa occurring in the testis, with SFPQ⁃TFE3 rearrangement. CASE PRESENTATION: A 57-year-old male touched a mass in his testis incidentally. MRI revealed a 10 mm diameter mass in the right testis. The patient underwent radical orchiectomy. Gross examination revealed a well-demarcated mass from the surrounding testicular tissue. Microscopically, the tumor mainly displayed nested or sheet-like architecture separated by delicate fibrovascular septa. The tumor cells exhibited marked nuclear atypia and pleomorphism. Immunohistochemistry showed that the tumor cells were strongly positive for cathepsin-K, HMB45 and TFE3. Molecular analysis revealed SFPQ⁃TFE3 gene fusion. Thus, it was diagnosed as primary Xp11 translocation PEComa of the testis. CONCLUSIONS: The present case reports primary Xp11 translocation PEComa of the testis for the first time, which to our knowledge has not been described in the literature in this anatomic site, where it could potentially be problematic in diagnosis.

Clinicopathological and molecular analysis of microsatellite instability in prostate cancer: a multi-institutional study in China.

Background: Microsatellite instability (MSI), or mismatch repair-deficiency (dMMR), is rare in prostate cancers (PCas). The histological and molecular features of PCas with MSI/dMMR are incompletely described. Thus, we sought to identify the characteristics of PCas with MSI/dMMR. Methods and results: We analyzed 1,141 primary treatment-naive PCas by MMR-related protein immunohistochemistry (MLH1, PMS2, MSH2, and MSH6). We identified eight cases exhibiting MSI/dMMR (0.7%, 8/1141). Of these, six tumors had both MSH2 and MSH6 protein loss, one had both MLH1 and PMS2 protein loss, and one had only MSH6 loss. Histologically, MSI/dMMR-PCas frequently demonstrated high histological grade (Grade Group 4 or 5), ductal/intraductal histology (6/8 cases), pleomorphic giant-cell features (4/8 cases), and conspicuous tumor lymphocytic infiltration (8/8 cases). Polymerase chain reaction-based analysis of seven MSI/dMMR tumors revealed two MSI-H tumors with loss of both MSH2 and MSH6 proteins. Subsequently, the seven cases underwent next-generation sequencing (NGS) analysis with a highly validated targeted panel; four were MSI. All cases had a high tumor mutation burden (median: 45.3 mutations/Mb). Overall, the MSI/dMMR-PCas showed a high frequency of DNA damage-repair pathway gene changes, including five with pathogenic somatic or germline MMR gene mutations. Activating mutations in the MAPK pathway, PI3K pathway, and WNT/ß-catenin pathway were common. TMPRSS2::ERG rearrangement was identified in one case (1/7, 14.3%). Conclusions: Several pathological features are associated with MSI/dMMR in PCas. Identification of these features may help to select patients for genetic screening. As MSI/dMMR-PCas are enriched for actionable mutations, patients should be offered NGS to guide standard-of-care treatment.

EspB and HtpG interact with the type III-A CRISPR/Cas system of Mycobacterium tuberculosis.

Introduction: Mycobacterium tuberculosis (MTB) has a type III-A clustered regularly interspaced short palindromic repeat/CRISPR-associated protein (CRISPR/Cas) system consisting of a Csm1-5 and CRISPR RNA (crRNA) complex involved in the defense against invading nucleic acids. However, CRISPR/Cas system in the MTB still is clearly unknown and needs to be further explored. Methods: In our work, two non-Cas system proteins EspB and HtpG protein were found and identified by LC-MS/MS. The effect of EspB and HtpG on Type III-A CRISPR/Cas System of M. tuberculosis was examined by using Plasmid interference assay and Co-immunoprecipitation analyses. We explored that EspB could interact with the crRNA RNP complex, but HtpG could inhibit the accumulation of the MTB Csm proteins and defense the mechanism of CRISPR/Cas system. Results: The proteins ESAT-6 secretion system-1(Esx-1) secreted protein B (EspB) and high-temperature protein G (HtpG), which were not previously associated with CRISPR/Cas systems, are involved in mycobacterial CRISPR/Cas systems with distinct functions. Conclusion: EspB is a novel crRNA-binding protein that interacts directly with the MTB crRNP complex. Meanwhile, HtpG influences the accumulation of MTB Csm proteins and EspB and interferes with the defense mechanism of the crRNP complex against foreign DNA in vivo. Thereby, our study not only leads to developing more precise clinical diagnostic tool to quickly detect for MTB infection, but also knows these proteins merits for TB biomarkers/vaccine candidates.

A combined clinicopathologic analysis of 658 urothelial carcinoma cases of urinary bladder.

OBJECTIVE: To study the clinicopathological features of patients with urothelial carcinoma of the urinary bladder (UCB), and analyze the association of clinicopathological characteristics with tumor recurrence and progression. METHODS: Altogether 658 UCB cases in Fudan University Shanghai Cancer Center were collected from January 2006 to December 2010. The histopathologic materials and the clinical records were reviewed. Univariate and multivariate analyses were preformed to detect the association. RESULTS: The mean age of the patients was 61.97 +/- 12.97 years (range, 20-90 years). Male to female ratio was about 5:1. A total of 517 cases (78.6%) were superficial at the time of diagnosis (stage Ta/T1). The mean follow-up period was 22.36 +/- 24.92 months. Twenty-five patients lacking follow-up information were excluded in calculating recurrence and progression rates, the recurrence rate was about 37.0% (234/633), and progression rate about 6.2% (39/633). Three variables (grade, tumor growth pattern, and pathological stage) were found to be significant risk factors for tumor progression in univariate and multivariate analyses (P < 0.05). CONCLUSIONS: Most of the newly diagnosed UCB cases may be superficial diseases. Grade, tumor growth pattern, and pathological stage are associated with tumor progression of UCB.

Low-grade oncocytic tumor of kidney harboring TSC/MTOR mutation: clinicopathologic, immunohistochemical and molecular characteristics support a distinct entity.

Low-grade oncocytic tumor (LOT) has recently been described as a distinct renal tumor. LOT shows consistent morphologic features and a CK7-positive/CD117-negative immunophenotype. To examine the clinicopathological, immunohistochemical, and molecular features of LOT, we searched our institutional archives and identified seven cases of LOT. All patients were female, with a mean age of 66 years (range 44-79 years). The average tumor size was 3.2 cm (range 1.6-5.5 cm). Macroscopically, the tumors showed tan-brown and solid cut surfaces. Microscopically, the tumors showed compact nested to solid growth pattern, three cases with areas of edematous stroma containing loosely connected small clusters, cords or dispersed single tumor cells. The tumor cells had uniformly round to oval nuclei with eosinophilic cytoplasm, and showed perinuclear halos. Two cases focally had nuclear irregularities and binucleated cells were occasionally seen in three cases. Immunohistochemically, diffuse positivity for CK7 and lack of CD117 expression were present in all cases. All of the tumors were negative for CD10, CK20, vimentin, CA9, TFE3, TFEB, HMB45, and Melan-A. All tumors were positive for MTOR and negative for Cathepsin-K. FH and SDHB were retained. Next generation sequencing identified genetic variations in the MTOR pathway related genes: TSC1 (4/7), TSC2 (5/7), and MTOR (1/7). All patients were alive and without disease progression, after a mean follow-up of 43 months (range 6-89 months). LOT is an uncommon eosinophilic renal neoplasm with unique morphological and characteristic immunophenotypic features, and may represent an emerging separate renal entity characterized by mutations in the TSC/MTOR pathway.