Molecular Characterization of Juxtaglomerular Cell Tumors: Evidence of Alterations in MAPK-RAS Pathway.

Juxtaglomerular cell tumor (JGCT) is a rare neoplasm, part of the family of mesenchymal tumors of the kidney. Although the pathophysiological and clinical correlates of JGCT are well known, as these tumors are an important cause of early-onset arterial hypertension refractory to medical treatment, their molecular background is unknown, with only few small studies investigating their karyotype. Herein we describe a multi-institutional cohort of JGCTs diagnosed by experienced genitourinary pathologists, evaluating clinical presentation and outcome, morphologic diversity, and, importantly, the molecular features. Ten JGCTs were collected from 9 institutions, studied by immunohistochemistry, and submitted to whole exome sequencing. Our findings highlight the morphologic heterogeneity of JGCT, which can mimic several kidney tumor entities. Three cases showed concerning histologic features, but the patient course was unremarkable, which suggests that morphologic evaluation alone cannot reliably predict the clinical behavior. Gain-of-function variants in RAS GTPases were detected in JGCTs, with no evidence of additional recurrent genomic alterations. In conclusion, we present the largest series of JGCT characterized by whole exome sequencing, highlighting the putative role of the MAPK-RAS pathway.

Nested and Large Nested Subtypes of Urothelial Carcinoma of the Upper Urinary Tract: A Multi-institutional Study.

Nested urothelial carcinoma (NUC) and large nested urothelial carcinoma (LNUC) of the upper urinary tract are exceedingly rare. This has contributed to the paucity of information regarding their clinicopathological and molecular characteristics. To address this knowledge gap, we explored the largest cohort to date of these rare tumors, comprising resection specimens of 10 LNUC and 7 NUC, from 7 participating institutions. Clinicopathological data were retrieved and documented. Whole exome sequencing and RNA sequencing were performed on the Illumina NovaSeq 6000 sequencer. The data generated were analyzed using the genome analysis toolkit pipeline. Somatic mutations were annotated using funcotator tool to identify pathogenic/likely pathogenic variants. Tumor mutational burden was calculated using python-based "pyTMB" tool. Microsatellite instability analysis was done using MSIsensor2 and the Idylla platform. Differential expression analysis of genes in LNUC and NUC along with mRNA expression-based molecular subtyping was performed by analyzing expression pattern of markers used in The Cancer Genome Atlas subclassification of bladder carcinoma. Both tumor types were more common in older males, were unifocal, and occurred more commonly mixed with minor components of predominantly conventional urothelial carcinoma. Overlying low-grade papillary urothelial carcinoma was significantly more common in LNUC (P = .034). On follow-up (LNUC: median, 10 months; range, 3-84 months; NUC: median, 9 months; range, 2-48 months), LNUC had better clinical outcomes (P = .031). Pathogenic mutations in FGFR3 and PIK3CA were significantly more common in LNUC (P = .049 and P = .044, respectively), with the latter present exclusively in LNUC. Seventy-five percent of the cases showed tumor mutational burden of <10, and all cases were microsatellite-stable. FGFR3 mutations were also more common in low-stage tumors. This study expands on the clinicopathological spectrum of NUC and LNUC of the upper urinary tract and is the first to comprehensively analyze the molecular profile of these tumors, highlighting pathogenic genetic alterations of potential therapeutic and prognostic value.

PD-L1 (22C3) Expression Correlates with Clinical and Molecular Features of Lung Adenocarcinomas in Cytological Samples.

INTRODUCTION: PD-L1 expression is the most widely used predictive marker for immune checkpoint inhibitor (ICI) therapy in patients with lung adenocarcinoma. However, the current understanding of the association between PD-L1 expression and treatment response is suboptimal. A significant percentage of patients have only a cytological specimen available for clinical management. Therefore, it is relevant to examine the impact of molecular features on PD-L1 expression in cytological samples and how it might correlate with a therapeutic response. METHODS: We evaluated patients diagnosed with adenocarcinoma of the lung who had both in-house targeted next-generation sequencing analysis and paired PD-L1 (22C3) immunohistochemical staining performed on the same cell blocks. We explored the association between molecular features and PD-L1 expression. In patients who underwent ICIs therapy, we assessed how a specific gene mutation impacted a therapeutic response. RESULTS: 145 patients with lung adenocarcinoma were included in this study. PD-L1-high expression was found to be more common in pleural fluid than in other sample sites. Regional lymph node samples showed a higher proportion of PD-L1-high expression (29%) compared with lung samples (6%). The predictive value of PD-L1 expression was retained in cytological samples. Mutations in KRAS were also associated with a PD-L1-high expression. However, tumors with TP53 or KRAS mutations showed a lower therapy response rate regardless of the PD-L1 expression. CONCLUSION: Cytological samples maintain a predictive value for PD-L1 expression in patients with lung adenocarcinoma as regards the benefit of ICI treatment. Specific molecular alterations additionally impact PD-L1 expression and its predictive value.

Pathologic, immunologic, and clinical analysis of the microsatellite instability phenotype in endometrial carcinoma.

The objective of this study was to determine if quantifying the microsatellite instability (MSI) phenotype could serve as a biomarker for clinical and immunologic features of deficient mismatch repair (dMMR) endometrial cancer (EC). Patients with EC undergoing hysterectomy whose tumors demonstrated dMMR were included. Immunohistochemistry (IHC) of mismatch repair proteins and polymerase chain reaction analysis of NR27, BAT25, BAT26, NR24, and NR21 microsatellite loci were performed on each case. The MSI phenotype was quantified by subtracting the number of nucleotides of each microsatellite in tumor tissue from the corresponding microsatellite in paired normal tissue and summing the absolute differences. This was termed marker sum (MS) and is a novel quantification. Tumor-infiltrating lymphocytes (TILs) were identified by IHC for CD3, CD4, and CD8 and quantified with digital image analysis. Tumor infiltration of lymphocytes and clinical characteristics were stratified by MS. Four hundred fifty-nine consecutive patients with dMMR EC were analyzed. MS ranged from 1 to 32. Post hoc, 2 cohorts were defined using receiver operating characteristic curves (MS less than 13 and MS greater than 12). With the exception of tumor grade, all clinical and pathologic features, all tumor characteristics, and the numbers of TILs were similar between cohorts. The MSI phenotype is highly variable in dMMR EC, and no correlation between the immune profile and the severity of the MSI phenotype was observed.

Spindle Cell Sarcoma of the Uterus Harboring MEIS1::NCOA1 Fusion Gene and Mimicking Endometrial Stromal Sarcoma.

MEIS1::NCOA1/2 sarcomas are a newly recognized group of exceedingly rare low-grade spindle cell sarcomas that often involve the genitourinary and gynecologic tracts. Due to its deceptively low-grade morphology and the non-specific immunoprofile, these neoplasms may pose a diagnostic challenge by histologically mimicking other entities such as endometrial stromal sarcoma, smooth muscle tumor, or uterine perivascular epithelioid cell tumor (PEComa). Histologically, MEIS1::NCOA1/2 sarcomas typically show spindle cell proliferation with hyperchromatic nuclei and a generalized cytologic uniformity, arranged in short fascicles and exhibiting alternating zones of hypo- and hypercellularity. Among the previously reported cases, molecular analysis revealed the MEIS1::NCOA2 fusion as the most commonly detected fusion gene, whereas the MEIS1::NCOA1 fusion gene has been reported in only a single case that involved kidney. Herein we report the first case of uterine sarcoma harboring the MEIS1::NCOA1 fusion gene that was initially misclassified as low-grade endometrial stromal sarcoma, demonstrating its clinicopathologic features, and highlighting the essential role of molecular pathology to arrive at the accurate diagnosis that may alter disease classification and inform therapy.

Oral and Inhaled Fosamprenavir Reverses Pepsin-Induced Damage in a Laryngopharyngeal Reflux Mouse Model.

OBJECTIVE: More than 20% of the US population suffers from laryngopharyngeal reflux. Although dietary/lifestyle modifications and alginates provide benefit to some, there is no gold standard medical therapy. Increasing evidence suggests that pepsin is partly, if not wholly, responsible for damage and inflammation caused by laryngopharyngeal reflux. A treatment specifically targeting pepsin would be amenable to local, inhaled delivery, and could prove effective for endoscopic signs and symptoms associated with nonacid reflux. The aim herein was to identify small molecule inhibitors of pepsin and test their efficacy to prevent pepsin-mediated laryngeal damage in vivo. METHODS: Drug and pepsin binding and inhibition were screened by high-throughput assays and crystallography. A mouse model of laryngopharyngeal reflux (mechanical laryngeal injury once weekly for 2 weeks and pH 7 solvent/pepsin instillation 3 days/week for 4 weeks) was provided inhibitor by gavage or aerosol (fosamprenavir or darunavir; 5 days/week for 4 weeks; n = 3). Larynges were collected for histopathologic analysis. RESULTS: HIV protease inhibitors amprenavir, ritonavir, saquinavir, and darunavir bound and inhibited pepsin with IC50 in the low micromolar range. Gavage and aerosol fosamprenavir prevented pepsin-mediated laryngeal damage (i.e., reactive epithelia, increased intraepithelial inflammatory cells, and cell apoptosis). Darunavir gavage elicited mild reactivity and no discernable protection; aerosol protected against apoptosis. CONCLUSIONS: Fosamprenavir and darunavir, FDA-approved therapies for HIV/AIDS, bind and inhibit pepsin, abrogating pepsin-mediated laryngeal damage in a laryngopharyngeal reflux mouse model. These drugs target a foreign virus, making them ideal to repurpose. Reformulation for local inhaled delivery could further improve outcomes and limit side effects. LEVEL OF EVIDENCE: NA. Laryngoscope, 133:S1-S11, 2023.

Epithelioid and Clear Cell Solitary Fibrous Tumors: Clinicopathologic, Immunohistochemical, and Molecular Genetic Study of 13 Cases.

Solitary fibrous tumors (SFTs) are ubiquitous soft tissue neoplasms known for their protean histology and potentially aggressive behavior. Although most cases are composed of a monotonous proliferation of spindle cells, some tumors show unusual cytologic features. We have studied 13 SFTs that were characterized by a predominant population of round epithelioid cells with abundant eosinophilic cytoplasm and clear cell changes. The tumors occurred in 8 women and 5 men, aged 36 to 80 years (mean=63 y), and were located within the orbit (3), lower extremity (3), retroperitoneum (2), abdominal cavity (2), and superficial soft tissues of the neck, pelvis, and pubis (1 each). The tumors measured from 3.5 to 24.5 cm. Using a risk assessment system, 6 cases were stratified as low-risk tumors; 3 of these showed no evidence of recurrence or metastases from 6 to 18 years, and 1 tumor in the orbit recurred and led to the patient's demise. Five cases were of intermediate risk; clinical follow-up showed no evidence of recurrence or metastases from 3 to 4 years in 3 patients, and 1 patient suffered a recurrence 4 years after diagnosis. Two cases were high risk; 1 patient died after 1 year and the second patient experienced local recurrence at 4 years. Immunohistochemical studies showed nuclear positivity for STAT6 in 10 cases. CD34 immunohistochemistry was positive in 11 cases. A NAB2::STAT6 rearrangement was present in all cases. Epithelioid and clear cell SFT should be considered in the differential diagnosis of soft tissue neoplasms with epithelioid and clear cell morphology.

Thyroid Oncocytic (Hürthle Cell) Nodules With Longitudinal Nuclear Grooves: Clinicopathologic, Immunohistochemical, and Molecular Genetic Study of 15 Cases.

CONTEXT.­: Thyroid nodules with longitudinal nuclear grooves have been widely regarded as synonymous with papillary thyroid carcinoma (PTC). OBJECTIVE.­: To study a series of cases of thyroid nodules that exhibited oncocytic (Hürthle cell) features and contained longitudinal nuclear grooves yet failed to display aggressive behavior or the full features of papillary thyroid carcinoma. DESIGN.­: The clinicopathologic, immunohistochemical, and molecular genetic features of 15 patients with these features were studied. Next-generation sequencing was performed to examine 161 genes for oncogenic driver alterations associated with thyroid neoplasia. RESULTS.­: The lesions occurred in 11 women and 4 men aged 27 to 80 years and measured 0.2 to 2.3 cm in diameter (mean, 1.1 cm). The tumors were well circumscribed and noninvasive and showed a proliferation of large cells with abundant granular cytoplasm and centrally placed nuclei displaying scattered longitudinal nuclear grooves. Immunohistochemical stains were negative for HBME-1, galectin-3, and CK19 in all cases. NRAS pQ61R was detected in 6 cases, KRAS p.Q61E in 1 case, and AKT2 p.E17K in 1 case. None of the genetic changes classically associated with conventional PTC or with high-grade thyroid malignant neoplasms were identified. Clinical follow-up in 9 patients showed no evidence of recurrence or metastases between 2 and 13 years (mean, 5.7 years). CONCLUSIONS.­: Longitudinal nuclear grooves can be occasionally encountered in oncocytic (Hürthle cell) tumors and should not lead to a diagnosis of PTC in the absence of other features supporting that diagnosis.

Utility of Single-Gene Testing in Cancer Specimens.

Molecular testing is now considered the standard of care to screen for disease, confirm the diagnosis, guide management, and use target therapy. Currently, several testing strategies are being used. One of the most common strategies is single-gene testing, which is often conducted for known mutations, such as BRAF in melanoma and EGFR in lung cancer. Subsequently, next-generation sequencing (NGS), which tests many genes simultaneously, was developed using targeted gene panels, whole-exome, or whole-genome sequencing. Ordering the best diagnostic tool and choosing between single-gene testing and NGS depends on several factors. In this review, we discuss different single-gene testing methodologies and the impact of using them in comparison to NGS/multigene panel.

Desmoplastic Adamantinoma-like Thymic Carcinoma: Clinicopathologic, Immunohistochemical, and Molecular Study of 5 Cases.

Five cases of a heretofore unreported rare variant of thymic carcinoma characterized by a striking resemblance to adamantinoma of the mandible are described. The tumors occurred in 4 women and 1 man aged 58 to 76 years (mean: 67.8 y); they arose in the anterior mediastinum and measured from 5.3 to 12.0 cm in greatest diameter (mean: 8.9 cm). Presenting symptoms included chest pain, shortness of breath, and in 2 patients, pleural effusion. One tumor was asymptomatic and discovered incidentally. Histologically, the tumors were extensively desmoplastic, and the cellular proliferation was characterized by multiple islands of squamous epithelium with striking peripheral palisading of nuclei and central areas containing clear cells resembling a stellate reticulum. Areas of preexisting spindle cell thymoma were identified in 2 cases; these areas gradually merged with the higher-grade component of the lesion. Cystic changes were noted in 3 cases. Immunohistochemical studies in 3 cases showed the tumor cells were positive for cytokeratins, p40 and p63, and all showed a high proliferation rate (>50% nuclear positivity) with Ki-67. Next-generation sequencing was performed in 2 cases that showed amplification of the AKT1 gene (copy numbers 6 and 13). Clinical follow-up in 3 patients showed recurrence and metastasis after 1 and 2 years; 1 patient passed away 2 years after diagnosis due to the tumor. Desmoplastic adamantinoma-like thymic carcinoma represents an unusual histologic variant of thymic carcinoma that needs to be distinguished from metastases from similar tumors to the mediastinum.

Performance of Idylla KRAS assay on extracted DNA and de-stained cytology smears: Can we rescue small sample?

OBJECTIVE: KRAS is a frequently mutated gene in cancers, and with recent FDA-approved targeted therapy for the G12C mutation, testing for KRAS variants is essential. We evaluated the performance of the Idylla KRAS assay on extracted DNA and cytology smears in order to expand the utility of the assay. METHODS: In total, fifty-seven human samples were analyzed. Idylla results from sixteen DNA extracted from formalin-fixed, paraffin-embedded tissues (FFPE DNA) and thirty cytology smears were compared to the reference method. We evaluated the performance of the Idylla assay using corresponding cytology smears to rescue cellblocks or surgical blocks that were quantity not sufficient (QNS) for next generation sequencing (NGS). RESULT: In the FFPE DNA cohort, 10 ng DNA input yielded valid results in all 16 samples, with 15 of 16 (93 %) concordant with NGS findings. In the cytology smear cohort, the Idylla KRAS assay demonstrated 100 % concordance with previous NGS results in 30 cases. In the QNS cohort, the assay was valid in all cases and KRAS mutations were identified in 3 of 11 cytology smears, including one G12C mutation. CONCLUSION: The Idylla KRAS assay is a high-performing, feasible, and convenient option for testing extracted DNA and cytology smears. It rescues QNS samples allowing it to be integrated into the molecular workflow as an initial screening test with remarkably quick turnaround times.

The diagnostic utility of RNA-based fusion panel testing ordered by pathologists in challenging cases.

INTRODUCTION: Gene fusion identification by RNA-based next-generation sequencing (NGS) provides important information for cancer patients. NGS is commonly initiated by treating oncologists to identify therapeutic options. However, the implications of large fusion panels on tumor classification and diagnosis are underappreciated. We investigated the extent to which these tests aid diagnosis when ordered by pathologists. METHODS: We retrospectively reviewed the results of a validated Archer FusionPlex panel ordered by surgical pathologists at our institution, excluding cases tested for therapeutic targets. One hundred thirty-five cases of solid tumors from October 2020 and September 2021 were included. We compared the initial diagnosis to the final diagnosis, which incorporated fusion gene results. We classified the cases into groups based on the degree of contribution of the RNA fusion panel to the final diagnosis. RESULTS: Among 135 cases, a fusion event was identified in 47 cases, and no fusion event was identified in 88 cases. The results changed the diagnosis in 4 of 135 fusion positive cases (3%). Twenty-one cases (15%) provided a more specific diagnosis, and original diagnosis was confirmed in 17 cases (13%). In the remaining 5 cases (4%), the results identified fusion events of unknown clinical significance. CONCLUSIONS: RNA-based NGS provides significant benefit as an ancillary diagnostic tool. In our cohort, fusion analysis provided a more definitive diagnosis in 25 cases (19%). Our findings demonstrate an important role for pathologists in appropriate utilization of molecular testing, and diagnostic workflows integrating RNA-based NGS will lead to more accurate diagnosis and better patient care.

Lymphocyte-Rich Spindle Cell Thymoma: Clinicopathologic, Immunohistochemical, Ultrastructural and Molecular Genetic Study of 80 Cases.

A study of 80 cases of spindle cell thymoma in which the spindle cell component was overshadowed by massive numbers of stromal lymphocytes is presented. The patients were 38 women and 42 men, aged 8 to 81 years (mean=54 y). All tumors presented as an anterior mediastinal mass; 5 patients had myasthenia gravis and one had Good syndrome. The tumors were well-circumscribed, encapsulated, and measured 2.9 to 26.0 cm in greatest diameter (mean=7.3 cm). Using modified Masaoka staging, 66 tumors were stage I, 10 were stage IIa, 2 were stage III and 1 was stage IV. Histologically the tumors were characterized by a predominant lymphocytic population admixed with scattered small spindle epithelial cells. The neoplastic spindle cells in these tumors demonstrated 2 major growth patterns: in 33 cases, the tumors were exclusively composed of dense sheets of lymphocytes containing scattered spindle cells resembling a lymphocyte-rich thymoma (WHO type B1); in the remaining cases the tumors showed admixtures of a predominantly lymphocytic component with areas that were lymphocyte-poor and contained a pure spindle cell population similar to WHO type A. Immunohistochemical stains and electron microscopy corroborated the spindle cell morphology in both types. The GTF2I p.L424H variant was identified in 53 of 63 (84%) cases analyzed. Clinical follow-up in 27 cases showed that most of the tumors behaved in an indolent manner. Our study expands the spectrum of spindle cell thymoma by demonstrating the existence of cases that are predominantly composed of lymphocyte-rich elements and lack areas with a pure (lymphocyte poor) spindle cell morphology.

Immature Chondroid Choristoma: Clinicopathologic, Immunohistochemical, and Molecular Study of an Unusual Benign Skin Tumor.

ABSTRACT: An unusual benign skin tumor is reported occurring in a 68-year-old woman with no significant medical history. The lesion presented as a small skin nodule in the neck. Histologic examination showed a well-circumscribed superficial dermal nodule composed of a solid proliferation of large, round cells with abundant eosinophilic cytoplasm and small centrally placed nuclei displaying a vaguely chondroid appearance. Immunohistochemical studies showed strong positivity of the tumor cells for S100 protein and vimentin and negative staining for SOX10, melanoma cocktail, HMB45, Melan-A, cytokeratin AE1/AE3, inhibin, desmin, smooth muscle actin, CD68, CD164, and neuron specific enolase. Next-generation sequencing using a panel of 50 actionable genes commonly encountered in human neoplasia did not reveal the presence of any mutations. Owing to the remarkable similarity of the lesion to immature cartilage, we consider this to be a benign tumor, most likely resulting from an embryologic defect. We propose the term immature chondroid choristoma to designate this lesion.

The Interpretation of Sequence Variants in Myeloid Neoplasms.

OBJECTIVES: To provide an overview of the challenges encountered during the interpretation of sequence variants detected by next-generation sequencing (NGS) in myeloid neoplasms, as well as the limitations of the technology with the goal of preventing the over- or undercalling of alterations that may have a significant effect on patient management. METHODS: Review of the peer-reviewed literature on the interpretation, reporting, and technical challenges of NGS assays for myeloid neoplasms. RESULTS: NGS has been integrated widely and rapidly into the standard evaluating of myeloid neoplasms. Review of the literature reveals that myeloid sequence variants are challenging to detect and interpret. Large insertions and guanine-cytosine-heavy areas prove technically challenging while frameshift and truncating alterations may be classified as variants of uncertain significance by tertiary analysis informatics pipelines due to their absence in the literature and databases. CONCLUSIONS: The analysis and interpretation of NGS results in myeloid neoplasia are challenging due to the varied number of detectable gene alterations. Familiarity with the genomic landscape of myeloid malignancies and knowledge of the tools available for the interpretation of sequence variants are essential to facilitate translation into clinical and therapy decisions.

Diagnostic utility of one-stop fusion gene panel to detect TFE3/TFEB gene rearrangement and amplification in renal cell carcinomas.

MiT family translocation renal cell carcinoma (MiT-RCC) harbors translocations involving the TFE3 or TFEB genes. RCC with TFEB amplification is also identified and is associated with a more aggressive clinical course. Accurate diagnosis of MiT-RCC is crucial for patient management. In this study, we evaluated the performance of the Archer FusionPlex assay for detection of MiT-RCC with TFE3 or TFEB translocations and TFEB amplifications. RNA was extracted from 49 RCC FFPE tissue samples with known TFE3/TFEB status (26 TFE3 FISH positive, 12 TFEB FISH positive, 4 TFEB amplified (1 case both split and amplified), and 8 FISH negative) using the Covaris extraction kit. Target enriched cDNA libraries were prepared using the Archer FusionPlex kit and sequenced on the Illumina NextSeq 550. We demonstrate that the age of the specimen, quality of RNA, and sequencing metrics are important for fusion detection. Fusions were identified in 20 of 21 cases less than 2 years old, and TFE3/TFEB rearrangements were detected in all cases with Fusion QC ≥ 100. The assay identified intrachromosomal inversions in two cases (TFE3-RBM10 and NONO-TFE3), usually difficult to identify by FISH assays. TFEB mRNA expression and the TFEB/TFE3 mRNA expression ratio were significantly higher in RCCs with TFEB fusion and TFEB gene amplification compared to tumors without TFEB fusion or amplification. A cutoff TFEB/TFE3 ratio of 0.5 resulted in 97.3% concordance to FISH results with no false negatives. Our study demonstrates that the FusionPlex assay successfully identifies TFE3 and TFEB fusions including intrachromosomal inversions. Age of the specimen and certain sequencing metrics are important for successful fusion detection. Furthermore, mRNA expression levels may be used for predicting cases harboring TFEB amplification, thereby streamlining testing. This assay enables accurate molecular detection of multiple subtypes of MiT-RCCs in a convenient workflow.

TFEB rearranged renal cell carcinoma. A clinicopathologic and molecular study of 13 cases. Tumors harboring MALAT1-TFEB, ACTB-TFEB, and the novel NEAT1-TFEB translocations constantly express PDL1.

Renal cell carcinomas with t(6;11) chromosome translocation has been classically characterized by the rearrangement of the TFEB gene, located on chromosome 6, and MALAT1 gene, located on chromosome 11. Recently, a few other genes have been described as fusion partners in TFEB rearranged renal cell carcinomas. Although most of TFEB rearranged renal cell carcinomas have an indolent behavior, in the rare cases of advanced metastatic disease targeted therapy and predictive markers remain lacking. In the present study, we collected 13 TFEB rearranged renal cell carcinomas, confirmed by FISH, analyzing their morphology and exploring the novel gene partners. Looking for predictive markers, we have also performed PDL1 immunohistochemical analysis by using four different assays (E1L3N, 22C3, SP142, and SP263). MALAT1 gene rearrangement has been found in ten tumors, five cases showing classical biphasic morphology with "rosettes", five cases without "rosettes" mimicking other renal cell carcinomas or epithelioid angiomyolipoma/pure epithelioid PEComa. We identified two different partner genes, ACTB and NEAT1, the latter previously unreported and occurring in a tumor with an unusual solid and cystic appearance. In both cases, the "rosettes" were absent. In one case no gene partner was identified. Overall, in 12 of 13 TFEB-rearranged renal cell carcinomas staining for PDL1 SP263 was observed, whereas the other antibodies were less reliable or more difficult to interpret. In conclusion, we described the third case of ACTB-TFEB rearranged renal cell carcinoma and a novel NEAT1-TFEB rearranged renal cell carcinoma, both without the distinctive biphasic morphology typical of t(6;11) renal cell carcinoma. Finally, PDL1 SP263 was constantly expressed in TFEB rearranged renal cell carcinoma with possible clinical benefit which requires further investigations.