Clinical Pearls and Advances in Molecular Researches of Epilepsy-Associated Tumors

Low-Grade Gliomas: Histological Subtypes, Molecular Mechanisms, and Treatment Strategies

Low-Grade Gliomas (LGGs) represent a diverse group of brain tumors originating from glial cells, characterized by their unique histopathological and molecular features. This article offers a comprehensive exploration of LGGs, shedding light on their subtypes, histological and molecular aspects. By delving into the World Health Organization's grading system, 5th edition, various specificities were added due to an in-depth understanding of emerging laboratory techniques, especially genomic analysis. Moreover, treatment modalities are extensively discussed. The degree of surgical resection should always be considered according to postoperative quality of life and cognitive status. Adjuvant therapies focused on chemotherapy and radiotherapy depend on tumor grading and invasiveness. In the current literature, emerging targeted molecular therapies are well discussed due to their succinctly therapeutic effect; in our article, those therapies are summarized based on posttreatment results and possible adverse effects. This review serves as a valuable resource for clinicians, researchers, and medical professionals aiming to deepen their knowledge on LGGs and enhance patient care.

Pediatric-type diffuse low-grade glioma with MYB/MYBL1 alteration: report of 2 cases

2016 World Health Organization (WHO) Classification of Tumors of the Central Nervous System (CNS) has shown how molecular features can impact the classification of brain tumors. The continued combination of molecular features with histopathology has led to distinguish tumors with similar histopathologic features but distinct clinical prognosis. The 2021 revised 5. edition of the WHO classification further includes molecular features for CNS tumor categorization including MYB/MYBL1 altered diffuse astrocytoma which is a newly recognized type of low-grade pediatric-type brain tumor. We discuss imaging features of two pediatric-type low-grade gliomas with MYB/MYBL1-mutation that encountered at our institution.

Low-grade epilepsy-associated neuroepithelial tumors: Tumor spectrum and diagnosis based on genetic alterations

Brain tumors can always result in seizures when involving the cortical neurons or their circuits, and they were found to be one of the most common etiologies of intractable focal seizures. The low-grade epilepsy-associated neuroepithelial tumors (LEAT), as a special group of brain tumors associated with seizures, share common clinicopathological features, such as seizure onsets at a young age, a predilection for involving the temporal lobe, and an almost benign course, including a rather slow growth pattern and thus a long-term history of seizures. Ganglioglioma (GG) and dysembryoplastic neuroepithelial tumor (DNET) are the typical representatives of LEATs. Surgical treatments with complete resection of tumors and related epileptogenic zones are deemed the optimal way to achieve postoperative seizure control and lifetime recurrence-free survival in patients with LEATs. Although the term LEAT was originally introduced in 2003, debates on the tumor spectrum and the diagnosis or classification of LEAT entities are still confusing among epileptologists and neuropathologists. In this review, we would further discuss these questions, especially based on the updated classification of central nervous system tumors in the WHO fifth edition and the latest molecular genetic findings of tumor entities in LEAT entities.

Multi-Omics Analysis of Key microRNA-mRNA Metabolic Regulatory Networks in Skeletal Muscle of Obese Rabbits

microRNAs (miRNAs), small non-coding RNA with a length of about 22 nucleotides, are involved in the energy metabolism of skeletal muscle cells. However, their molecular mechanism of metabolism in rabbit skeletal muscle is still unclear. In this study, 16 rabbits, 8 in the control group (CON-G) and 8 in the experimental group (HFD-G), were chosen to construct an obese model induced by a high-fat diet fed from 35 to 70 days of age. Subsequently, 54 differentially expressed miRNAs, 248 differentially expressed mRNAs, and 108 differentially expressed proteins related to the metabolism of skeletal muscle were detected and analyzed with three sequencing techniques (small RNA sequencing, transcriptome sequencing, and tandem mass tab (TMT) protein technology). It was found that 12 miRNAs and 12 core genes (e.g., CRYL1, VDAC3 and APIP) were significantly different in skeletal muscle from rabbits in the two groups. The network analysis showed that seven miRNA-mRNA pairs were involved in metabolism. Importantly, two miRNAs (miR-92a-3p and miR-30a/c/d-5p) regulated three transcription factors (MYBL2, STAT1 and IKZF1) that may be essential for lipid metabolism. These results enhance our understanding of molecular mechanisms associated with rabbit skeletal muscle metabolism and provide a basis for future studies in the metabolic diseases of human obesity.

Clinical Relevance of Interictal Spikes in Tumor-Related Epilepsy: An Electrocorticographic Study

Background and Purpose

Although some surgeons utilize interictal spikes recorded via electrocorticography (ECoG) when planning extensive peritumoral resection in patients with tumor-related epilepsy, the association between interictal spikes and epileptogenesis has not been fully described. We investigated whether the resection of interictal spikes recorded by ECoG is associated with more favorable surgical outcomes in tumor-related epilepsy.

Methods

Of 132 patients who underwent epilepsy surgery for tumor-related epilepsy from 2006 to 2013, seven patients who underwent extraoperative ECoG were included in this study. In each patient, ECoG interictal spike sources were localized using standardized low-resolution brain electromagnetic tomography and were co-registered into a reconstructed brain model. Correspondence to the resection volume was estimated by calculating the percentage of interictal spike sources in the resection volume.

Results

All patients achieved gross total resection without oncological recurrence. Five patients achieved favorable surgical outcomes, whereas the surgical outcomes of two patients were unfavorable. Correspondence rates to the resection volume in the favorable and unfavorable surgical outcome groups were 44.6%±27.8% and 43.5%±22.8%, respectively (p=0.96). All patients had interictal spike source clusters outside the resection volume regardless of seizure outcome.

Conclusions

In these cases of tumor-related epilepsy, the extent of the resection of ECoG interictal spikes was not associated with postoperative seizure outcomes. Furthermore, the presence of interictal spike sources outside of the resection area was not related to seizure outcomes. Instead, concentrating more on the complete removal of the brain tumor appears to be a rational approach.

Polymorphous Low-Grade Neuroepithelial Tumor of the Young: A Case Report with Genomic Findings

BACKGROUND

Polymorphous low-grade neuroepithelial tumor of the young (PLNTY) is a recently recognized epileptogenic neuroepithelial tumor. Despite its distinctiveness, its polymorphous histology and the nature of its oligodendrocyte-like cells remain unclear.

CASE DESCRIPTION

A 30-year-old, right-handed man was diagnosed with intractable epilepsy since 22 years of age. Magnetic resonance imaging revealed T2 signal hyperintensity and corresponding T1 signal hypointensity within the subcortical white matter of the right middle temporal gyrus. Positron emission tomography scan demonstrated hypometabolism in the right anterior temporal region. Electroencephalography and stereo-electroencephalography monitoring localized seizures to the right temporal lobe, allowing the patient to undergo right temporal lobectomy. Histologic sections demonstrated cortical dysplasia, white matter heterotopia, and hippocampal reactive gliosis without neuronal loss. Interestingly, an approximately 6-mm subcortical neoplasm was identified in the temporal lobectomy. It was composed of well-differentiated oligodendroglial-like cells but exhibited mild-to-moderate nuclear variability and pleomorphism, and mild infiltration into the overlying cortex without perineuronal satellitosis. No mitotic activity, microvascular proliferation, or necrosis was identified, and Ki-67 labeling index was less than 1%. The tumor was diffusely CD34 positive with moderate glial fibrillary acidic protein and retained ATRX staining, and demonstrated the presence of the BRAF V600E mutation. The tumor was negative for reticulin condensation, synaptophysin, SMI31, neuronal nuclei immunostains, and both the IDH1 mutation and 1p19q codeletion. Overall histologic findings were most consistent with PLNTY.

CONCLUSIONS

The correct diagnosis of PLNTY and its distinction from closely resembling low-grade neuroepithelial tumors is important. We hope our proposed diagnostic features will aid in its proper diagnosis and management.