Luteinizing hormone-releasing hormone (LHRH) agonists are widely used for androgen-deprivation therapy in prostate cancer. Recent reports have raised concern that LHRH may influence the biological behavior of LHRH receptor-expressing intracranial tumors, including meningiomas; however, clinical evidence remains limited. We describe two cases of rapidly progressive meningioma temporally associated with the initiation of leuprorelin acetate. Case 1 was a 67-year-old man with a left cerebellopontine angle meningioma that had demonstrated gradual enlargement over 26 months. Following the initiation of leuprorelin acetate, the tumor exhibited accelerated growth, necessitating surgical resection. Pathology confirmed a fibrous meningioma with LHRH and its receptor positive. Case 2 was a 72-year-old man previously treated with subtotal resection and radiotherapy for an atypical meningioma. After 6 years of radiographic stability, the tumor rapidly regrew soon after leuprorelin acetate initiation and required re-resection. Both the primary and recurrent tumors were LHRH- and LHRH receptor-positive. Freshly resected tumor tissue cultured ex vivo demonstrated a dose-dependent increase in cell viability following 7-day exposure to leuprorelin acetate. These findings suggest that LHRH agonists may be associated with increased cell viability in a subset of receptor-positive meningiomas. Caution is warranted when initiating LHRH agonist therapy in patients with known or suspected meningiomas.
Ependymoma-like tumor with mesenchymal differentiation (ELTMD) is a recently proposed, but not yet formally defined, entity that is not recognized in the 2021 World Health Organization (WHO) classification of central nervous system tumors. Although it shares molecular features, such as ZFTA fusion, with ependymomas, it exhibits distinct histopathological and epigenetic profiles. Herein, we report the case of a 5-year-old girl with a supratentorial tumor harboring the ZFTA::NCOA2 fusion. Histopathology revealed atypical features including mesenchymal and undifferentiated components, which overlapped with those of ependymomas. DNA methylation profiling using two independent classifiers (DKFZ and NIH) yielded no matches, indicating that the tumor did not belong to any recognized CNS class. The failure of subclass assignment by both classifiers suggests that ELTMD represents a potentially epigenetically distinct subgroup. Despite being unclassifiable by the current WHO criteria, the tumor shared features with previously reported ELTMDs, supporting its recognition as an emerging tumor. This highlights the need for additional cases to refine the diagnosis, classification, and future therapeutic strategies.
Glioblastoma (GBM) is a highly lethal brain tumor resistant to immunotherapy such as immune checkpoint inhibitors, partly because of an immunosuppressive tumor microenvironment and blood–brain barrier (BBB) dysfunction. Although bevacizumab can remodel the tumor vasculature, the relationship between BBB-related vascular changes and immune cell infiltration in GBM remains poorly understood. We analyzed human isocitrate dehydrogenase (IDH)-wildtype GBM tissues obtained after bevacizumab administration. Immunohistochemistry was performed for CD34 and plasmalemma vesicle-associated protein (PLVAP/PV-1), an endothelial marker associated with BBB disruption. Infiltrating T cells (CD3, CD8) and tumor-associated macrophages/microglia (TAMs; CD163) were also examined. PLVAP was broadly expressed in tumor vessels of untreated GBM and significantly reduced after bevacizumab administration, with marked downregulation in 3 of 10 treated cases. Among the 10 treated cases, significant increases in T-cell and cytotoxic T-lymphocyte infiltration were seen in PLVAP-low GBM compared with PLVAP-high GBM. TAM density did not differ significantly between groups but tended to be higher in the PLVAP-low group. These findings suggest that the bevacizumab-associated reduction of PLVAP expression is linked to increased T-cell infiltration in a subset of GBM cases. PLVAP may serve as an auxiliary histological marker for evaluating bevacizumab-related vascular/BBB remodeling in clinical specimens.
The 2021 World Health Organization (WHO) Classification of Tumors of the Central Nervous System, 5th Edition, defines diffuse pediatric-type high-grade glioma, H3-wildtype and IDH-wildtype (dpHGG, H3-/IDH-WT) as a molecularly distinct entity, primarily diagnosed by DNA methylation profiling. Although this tumor predominantly occurs in children, its clinicopathological characteristics in adults are poorly understood. Here, we report two adult patients with cerebellar tumors that were histologically consistent with glioblastoma, but were reclassified as dpHGG, H3-/IDH-WT, RTK1 subtype based on genome-wide DNA methylation analysis. Both patients presented with large infiltrative cerebellar masses and experienced an aggressive clinical course with early postoperative progression. Histologically, the tumors exhibited high cellularity, marked cytological atypia, brisk mitotic activity, and microvascular proliferation without necrosis. Molecular analyses revealed PDGFRA amplification and homozygous deletion of CDKN2A in both cases, while neither showed EGFR amplification. These findings suggest that a subset of morphologically defined cerebellar glioblastomas in adults represents the dpHGG, H3-/IDH-WT, RTK1 subtype. Recognition of this underappreciated manifestation is important for accurate tumor classification, and further accumulation of well-characterized cases is required to clarify its clinical significance.
Rapid intraoperative differentiation between high-grade gliomas (HGGs) and primary central nervous system lymphomas (PCNSLs) is critical because surgical strategies and adjuvant therapies differ substantially. We conducted a multicenter prospective observational study to evaluate rapid immunohistochemistry (R-IHC) on frozen sections using alternating current electric field mixing. Forty-eight adults with newly suspected malignant intra-axial brain tumors underwent tumor resection or biopsy with intraoperative frozen section consultation. The prespecified primary endpoint was antibody level concordance between R-IHC and conventional immunohistochemistry on permanent formalin-fixed, paraffin-embedded sections. Intraoperative diagnostic performance using hematoxylin and eosin (HE) alone versus HE plus R-IHC was assessed descriptively. Final diagnoses were HGG in 37 patients, PCNSL in 8, and other lesions in 3. For HGG, HE-based intraoperative diagnosis showed 91.9
The occurrence of mesenchymal tumor, FET::CREB fusion-positive in the spinal compartment is exceptionally rare, with only a few previously documented cases. Here, we present a unique case of a 43-year-old man who developed a mesenchymal tumor, FET::CREB fusion-positive at the T1 spinal level. Clinically, the patient reported chronic posterior neck and shoulder pain accompanied by the intermittent paresthesia of the right arm. Magnetic resonance imaging demonstrated an intradural extramedullary mass, initially suggestive of a schwannoma. The patient underwent near-total surgical removal via a right C7-T1 hemilaminectomy. Histological examination revealed epithelioid and cord-like cellular arrangements within a mixed sclerotic and myxochondroid stroma. Immunohistochemistry revealed partial positivity for epithelial membrane antigen (EMA), smooth muscle actin (SMA), and CD99. Molecular analysis confirmed the presence of EWSR1::CREM fusion, establishing the diagnosis of a mesenchymal tumor, FET::CREB fusion-positive. To date, all reported spinal mesenchymal tumors within this molecular category have exclusively featured CREM as an FET gene family fusion partner, thereby highlighting a potential site-specific molecular signature. In this case report, we discuss the potential diagnostic challenges, characteristic pathological spectra, and clinical considerations associated with this rare entity of the spine.
Gliosarcoma is a rare and aggressive variant of glioblastoma characterized by biphasic glial and sarcomatous components. Lesions arising from the craniovertebral junction or brainstem are extremely uncommon, and their molecular pathogenesis remains poorly understood. A 69-year-old woman presented with rapidly progressive quadriparesis. Magnetic resonance imaging demonstrated an enhancing mass extending from the clivus to the medulla and an additional lesion in the ventricular trigone. Partial resection via an endoscopic transpharyngeal transclival approach achieved decompression. Histologically, the tumor exhibited distinct glial and sarcomatous components, with loss of H3K27me3 expression restricted to the sarcomatous areas. Comprehensive molecular profiling revealed mutations in PTEN, SUZ12, TERT, and EPHB1. Despite adjuvant radiation therapy, temozolomide, and bevacizumab, leptomeningeal dissemination occurred, and the patient died five months postoperatively. This rare case of gliosarcoma arising at the craniovertebral junction exhibited distinctive molecular and epigenetic features, including a SUZ12 mutation potentially associated with loss of H3K27me3. To our knowledge, gliosarcoma harboring these molecular abnormalities has not been previously reported. These findings may be associated with PRC2 dysfunction; however, their biological significance remains to be clarified. Comprehensive molecular profiling may contribute to improved diagnostic characterization of such rare entities.
Homozygous deletions of cyclin-dependent kinase inhibitor 2 A/B (CDKN2A/B) are recognized as poor prognostic markers in newly diagnosed IDH-mutant astrocytomas. However, a standardized definition of CDKN2A/B homozygous deletion has not yet been established. Furthermore, the prognostic significance of CDKN2A/B homozygous and hemizygous deletions at recurrence remains unclear. In this study, we investigated the prognostic impact of CDKN2A/B homozygous and hemizygous deletions in patients with recurrent IDH-mutant astrocytomas. We conducted a retrospective review of 32 patients treated at our institution between January 2006 and March 2023. CDKN2A/B homozygous and hemizygous deletions were defined as relative CDKN2A/B copy numbers of < 0.4 and < 0.7, respectively, as determined by multiplex ligation-dependent probe amplification. Univariate analysis demonstrated that both homozygous and hemizygous deletions at first recurrence were associated with shorter post-recurrence survival. Multivariable analysis identified both deletion types and histological grade at first recurrence as independent prognostic factors. Risk stratification based on histological grade and CDKN2A/B status effectively predicted survival outcomes following recurrence. In conclusion, CDKN2A/B status, alongside histological grading, represents an independent prognostic indicator in recurrent IDH-mutant astrocytoma.
Telomerase reverse transcriptase promoter (TERTp) mutations c.-124C > T (C228T) and c.-146C > T (C250T) are the most frequent single-nucleotide variants promoting telomerase activation in glioblastoma. Here, we describe a rare case of glioblastoma IDH-wildtype with dual TERTp mutations. Genomic analyses of multiregional tumor samples revealed co-occurring TERT C228T and C250T mutations across tumor regions, with variable copy number alterations of EGFR and CDKN2A. Notably, only the TERTp C228T mutation was retained in the corresponding patient-derived xenograft, accompanied by more extensive copy number alterations, implying a selective growth advantage for the TERT C228T-harboring subclone during tumor propagation in this case. These findings suggest that dual TERTp mutations may arise through subclonal evolutionary processes in glioblastoma and highlight telomere maintenance as a dynamic, heterogeneous process rather than invariably representing a fixed early oncogenic event.
Astroblastoma, MN1-altered, is a rare circumscribed glial neoplasm defined by alterations in the MN1 gene and often the MN1::BEND2 fusion. However, it is noted that a subset of these tumors lacks the classic astroblastic perivascular pseudorosettes, which can complicate diagnosis. We report a diagnostically challenging case in a 6-year-old female presenting with gait disturbance and limb weakness. MRI identified a well-defined fourth ventricular roof mass causing obstructive hydrocephalus. Histology post-resection revealed a solid tumor composed of epithelioid cells arranged in sheets and nests, exhibiting abundant cytoplasm, nuclear atypia, and prominent grooves, but no astroblastic pseudorosettes or significant mitosis. Immunohistochemically, tumor cells were negative for GFAP and Olig2, showed only focal EMA expression, but exhibited diffuse PR positivity. Methylation profiling did not match any established WHO CNS5 subtype, while targeted NGS identified a defining TCF3::BEND2 in-frame fusion. This case supports the existence of a phenotypically distinct variant within the spectrum of BEND2-rearranged neuroepithelial tumors, characterized by the TCF3::BEND2 fusion. Although molecularly related to MN1-altered astroblastoma, it displays distinct histological and immunophenotypic features. These findings further support the role of BEND2 as a potential oncogenic driver and underscore the importance of recognizing this fusion-defined tumor as a distinct variant within the astroblastoma-like spectrum.
We report a case with pilocytic astrocytoma (PA) morphology carrying a histone H3 K27M mutation (H3-K27M) that progressed to PA with anaplasia. A 34-year-old woman presented with headache due to obstructive hydrocephalus from a tectal lesion. She underwent subtotal tumor resection. Histology showed a biphasic architecture with piloid cells, consistent with PA. Five months later, she developed recurrence. A second, partial resection was performed, with pathology again indicating PA. Despite subsequent radiation and chemotherapy, the tumor progressed. A third resection was done 15 months after the second. This time, histology revealed PA with anaplasia. The patient died of progressive disease 25 months after initial treatment. KIAA1549::BRAF fusion, H3-K27M, and loss of p16 expression due to promoter methylation were detected in all specimens. In all specimens, the presence of NF1 Y2285fs*1 was confirmed by Sanger sequencing, with an increasing proportion of the aberrant sequence at the third resection. DNA methylation profiling revealed that the second and third specimens were classified as diffuse midline glioma, H3 K27-altered. This case suggests that the H3-K27M mutation, MAPK pathway activation, and loss of p16 expression contribute to tumorigenesis, while clonal proliferation of the tumor harboring the NF1 mutation may play a role in malignant progression.
A 67-year-old man presented with bilateral diplopia and gait instability. Brain magnetic resonance imaging revealed two adjacent lesions in the right middle cerebellar peduncle: a 2.7-cm cystic lesion with an enhancing mural nodule and a 1.7-cm ring-enhancing nodule with surrounding edema and associated brainstem compression. Biopsy followed by surgical resection demonstrated a biphasic tumor composed of glioma-like and epithelial-like components. Immunohistochemically, the glioma-like component expressed GFAP and OLIG2, whereas the epithelial-like component lacked glial and epithelial lineage markers and exhibited a high proliferative index (Ki-67 labeling index, 50%). Aberrant calponin-1 expression was observed in both components but was not associated with definitive smooth muscle or myoepithelial differentiation. DNA methylation profiling did not yield a definitive classification and demonstrated borderline similarity to established high-grade glioma classes, clustering near the glioblastoma, IDH-wild-type, midline subtype. Molecular analysis of the epithelial-like component was not feasible due to limited tissue availability, preventing assessment of clonal relatedness between components. This case illustrates the diagnostic challenges posed by intratumoral heterogeneity and sampling limitations in adult cerebellar high-grade gliomas. This report highlights the interpretive constraints of current histopathological and molecular classification frameworks when confronted with spatially heterogeneous tumors and incomplete sampling, rather than defining a novel tumor entity.
Here, we report a rare case of a 59-year-old woman with a TERT promoter-wildtype oligosarcoma developed after resection of an IDH-mutant oligodendroglioma with1p/19q codeletion followed by maintenance temozolomide therapy. The oligosarcoma exhibited distinct oligodendroglioma and sarcomatous components, both of which were diffusely positive for IDH1 R132H and showed strong, diffuse nuclear accumulation of p53. Molecular analyses were performed separately for each component using fluorescence in situ hybridization, Sanger sequencing, amplicon-based next generation sequencing, and DNA methylation profiling. The results indicated that the clones observed in oligodendroglial and sarcomatous components originated from a common precursor harboring IDH1 p.R132H, TP53 p.P250L, and PIK3CA p.C90G mutations together with 1p/19q codeletion, and subsequently acquired additional mutations and chromosomal abnormalities through subclonal evolution and biphenotypic differentiation. Specifically, the oligodendroglial component acquired a KRAS p.G12D mutation and polysomy of chromosome 1q and 19p, whereas the sarcomatous component harbored PTEN p.G165R and PTEN p.Q171* mutations and copy-number neutral loss of heterozygosity of 1p. No TERT promoter mutation was detected. DNA methylation profiling classified the gliomatous component of the oligosarcoma as “oligosarcoma, IDH-mutant” with a calibrated score of >0.99.
The prognostic significance of CDKN2A/B hemizygous deletion (HemD) in IDH-mutant astrocytomas (A-IDHm) remains unclear. We conducted a systematic review and WHO grade-specific meta-analysis of primary tumors following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Effect sizes included hazard ratios (HRs) and restricted mean survival time (RMST) for overall survival. The pooled frequency of HemD in grade 2 A-IDHm was 13.8
Primary intracranial mesenchymal tumors harboring FET::CREB gene fusions were recognized in the 2021 World Health Organization (WHO) Classification of Central Nervous System (CNS) tumors as a provisional entity within mesenchymal, non-meningothelial tumors. Most reported cases to date have arisen in the supratentorial region and abut the meninges. Herein, four cases of intracranial mesenchymal tumors with confirmed FET::CREB fusions are reported. Their clinical histories and neuroimaging findings were reviewed, and the histopathological, immunohistochemical, and molecular genetic features were further described. Three of the four cases showed lipoblastoid cells, and one showed irregular giant cells, which have not been described previously. Among the four cases, three were infratentorial with the same molecular profile EWSR1::CREM fusions and one was supratentorial with EWSR1::ATF1 fusion. Notably, the three infratentorial EWSR1::CREM fusion-positive tumors exhibited different morphologic characteristics from each other. DNA methylation profiling showed that the four tumors formed a unique cluster, besides, none of them clustered with established CNS tumors or extracranial sarcomas reference classes. All patients underwent gross total resection without adjuvant radiotherapy or chemotherapy, and no recurrences were observed during follow-up. Collectively, these tumors display a broad histological spectrum and appear to behave indolently or as low-grade malignancies. However, given the limited number of cases, larger cohorts are required to futher elucidate their biology and refine diagnostic stratification.
Telomerase reverse transcriptase (TERT) promoter mutations and cyclin-dependent kinase inhibitor 2A/2B (CDKN2A/B) homozygous deletion (HD) are strongly associated with meningioma recurrence. Therefore, it is important to accurately detect TERT promoter mutations and CDKN2A/B HD in meningiomas. Sanger sequencing and pyrosequencing are conventional methods used to analyze TERT promoter mutations. However, due to the high GC content around the TERT promoter mutation, PCR amplification by sequencing has proven to be technically difficult. In this report, we describe a novel digital PCR (dPCR) assay to evaluate TERT promoter mutations and CDKN2A HD in freshly frozen and formalin-fixed paraffin-embedded (FFPE) meningioma specimens and verify the difference in results from conventional methods. Of the 76 meningioma specimens, 10 and 17 specimens were detected by pyrosequencing and dPCR assays, respectively, to harbor TERT promoter mutations. And when using dPCR assay to detect CDKN2A HD, a cut-off value was set at 0.73, which gave a detection rate comparable to qPCR. Using a dPCR assay, TERT promoter mutations and CDKN2A HD can be detected approximately 2 h after tumor resection. Therefore, the dPCR assay is fast and sensitive compared to conventional methods, which can be of great help in treatment-strategy decision making.
NF2-related schwannomatosis is a tumor predisposition syndrome caused by diverse NF2 alterations, including truncating variants, copy-number changes, and non-truncating variants such as in-frame indels. Molecular and clinical correlations of these variant types remain incompletely defined, particularly for rare deletions. We present two distinct cases highlighting NF2 inactivation spectrum. Case 1 describes a 62-year-old man with a jugular foramen schwannoma harboring a novel somatic NF2 in-frame deletion (c.713_733del, p.Ala238_Tyr244del) resulting in complete Merlin expression loss. Structural modeling predicted FERM-C subdomain destabilization; copy-neutral loss of heterozygosity confirmed biallelic inactivation. Case 2 describes a 55-year-old woman with early-onset bilateral vestibular schwannomas caused by a germline whole-gene NF2 deletion, with additional somatic mutations (splice-site and frameshift) inactivating the second allele. Pedigree analysis demonstrated paternal inheritance, underscoring the relevance of genetic counseling. Both tumors displayed classical schwannoma histology with absent Merlin staining, confirming functional NF2 loss. These cases emphasize the necessity of comprehensive molecular testing—including targeted sequencing, whole-genome sequencing, and multiplex ligation-dependent probe amplification—to detect nucleotide-level and large-scale NF2 alterations; moreover, they expand the NF2 mutation spectrum, illustrate pathogenic mechanisms across germline and somatic contexts, and provide clinically actionable insights for Merlin-deficient tumors.
Posterior fossa group B (PFB) ependymoma in children poses diagnostic challenges, particularly when tissue is limited or histological features overlap with other entities. Unlike posterior fossa group A tumors, which show EZHIP overexpression and global H3K27me3 loss, recurrent single-nucleotide variants or other coding alterations in PFB remain largely unidentified, highlighting the importance of epigenetic profiling. We applied long-read nanopore sequencing to four pediatric posterior fossa tumors initially diagnosed as PFB ependymoma, including three specimens archived for more than a decade. DNA methylation profiles were analyzed using t-distributed stochastic neighbor embedding (t-SNE) and classified with the Epignostix CNS Tumor Methylation Classifier (v12.8), with comparison to matched Illumina EPIC array data. Cases 1 and 2 were classified as PFB, while Case 3 localized between the PFB and subependymoma clusters. Case 4 clustered with low-grade gliomas on t-SNE analysis, and long-read sequencing identified BRAF p.V600E mutation, excluding ependymoma. Nanopore- and array-based t-SNE embeddings showed concordant clustering across all cases. Long-read nanopore sequencing enabled reliable methylation-based classification from long-term archived tissue and allowed concurrent detection of methylation patterns and genomic alterations with a reduced turnaround time. These results support its feasibility as a complementary approach for integrated molecular diagnosis of central nervous system tumors.
BACKGROUND: BRAF mutations are key genetic alterations in pediatric gliomas, especially within the MAPK pathway-altered category of the 2021 WHO classification. The BRAF p.T599dup mutation is an extremely rare in-frame insertion reported in melanoma, thyroid, and lung carcinoma, and occasionally in pleomorphic xanthoastrocytoma or ganglioglioma. However, diffuse low-grade glioma harboring this mutation has not been well characterized. CASE PRESENTATION: An 8-year-old boy presented with a four-year history of seizures. MRI revealed a right temporal mass with a cystic component, and gross total resection was achieved. Histologically, the tumor showed diffuse infiltration of mildly atypical Olig2- and GFAP-positive glial cells without mitosis, microvascular proliferation, or necrosis. Sanger sequencing identified a rare BRAF p.T599dup mutation, whereas IDH1/2 and FGFR1 were wildtype. The tumor was diagnosed as diffuse low-grade glioma, MAPK pathway-altered, harboring BRAF p.T599dup. The patient has remained seizure-free and recurrence-free for 30 months without adjuvant therapy. CONCLUSION: This case represents one of the few diffuse low-grade gliomas harboring BRAF p.T599dup and provides detailed clinicopathological and molecular characterization of this rare alteration. The tumor closely resembled BRAF p.V600E-mutated gliomas, highlighting the diagnostic and therapeutic implications of recognizing such rare BRAF variants and the importance of integrating clinicopathological and molecular data for accurate classification.
PATZ1 fusion neuroepithelial tumors (NET) are beginning to be recognized as a distinct molecular class of neoplasms that most often occur in children and young adults. These tumors are polyphenotypic, show diverse morphologic features, may be low- or high-grade, and tend to have an intermediate prognosis. We present a rare case of a high-grade NET harboring an EWSR1::PATZ1 fusion, identified through DNA methylation profiling and validated by gene expression analysis. The case involved a 21-year-old female presenting with headaches and seizures. The tumor was supratentorial in close relation to the lateral ventricle, preferentially located in the parietal lobe. Morphologically it showed predominant sarcomatous morphology with high mitotic activity and a high Ki-67 index leading to its initial diagnosis of gliosarcoma. Awareness of the emerging entity of PATZ1 fusion NET is important not only for accurate diagnostic and prognostic purposes but also for predicting response to therapy.
