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Using the example of a recurrent tumor with a 10-year follow-up, the authors show that mutation of the IDH1/2 genes in astrocytomas is not always an early event in the pathogenesis of glioma, that in rare cases a 1p19q codeletion can be found in astrocytomas, and that IDH-mutant tumors can occur in childhood.

Background: Differential diagnosis of supratentorial ependymomas is of particular difficulty in neurooncology due to nonspecific clinical and radiographic findings, a rare seen «classic» morphological picture, and a nonspecific immunophenotype. Thanks to molecular genetic methods, in particular real-time PCR, it has become possible to verify supratentorial ependymomas and identify their molecular group, on which further prognosis depends., Objective: To develop a set of molecular genetic tests based on real-time PCR to verify supratentorial ependymomas., Material and Methods: 56 tissue samples were collected from patients with supratentorial ependymomas, WHO Grade II, and anaplastic ependymomas, WHO Grade III. We developed primers and fluorescent TaqMan probes for real-time PCR analysis to detect the ZFTA::RELA , ZFTA::MAML2 , ZFTA::NCOA2 , ZFTA::MAML3, YAP1::MAMLD1 , and YAP1::FAM118B gene fusions. For immunohistochemical analysis, monoclonal rabbit anti-NF-kb p65 antibodies (HUABIO, China) were used, the study was carried out on AutostainerLink 48 immunostainer (DAKO, Denmark)., Results: Real-time PCR was able to verify the diagnosis for 69.9% ( n =39) of samples and classify them into molecular groups of ZFTA- or YAP1-positive supratentorial ependymomas. Immunohistochemically it was possible to verify 58% ( n =29) ependymomas., Conclusion: Diagnosis by real-time PCR is a relatively fast, accessible and easily interpreted method that allows verification of the molecular group in 70% of cases of supratentorial ependymomas without the use of additional methods.

The review is focused on a relatively new research method in oncology - DNA methylation. Starting from the methylation of individual genes, the method is gradually expanding and becoming routine for studying the global structure of DNA methylation (methylome) in tumors of various localizations. For some tumors (carcinomas of the mammary and thyroid glands), the study of the global structure of DNA methylation is just beginning, while methylation classifiers have been proposed and successfully used in the Russian Federation for brain tumours and sarcomas. This article compares the fifth edition of the WHO Classification of tumours of the Central Neurvous System and the methylation brain classifier.

The paper presents the experience of using DNA methylation status in patients with meningiomas of the craniovertebral junction area in a neurosurgical clinic. A clinical case of combined treatment of a patient with meningioma of the craniovertebral junction and the choice of tactics based on the result of DNA methylation analysis of meningioma are described.

Identification of specific alterations in tumors (as a rule, these are mutations or gene fusions) makes it possible to prescribe targeted drugs of the second line of therapy or, in some cases of inoperable tumors, to observe not only a gradual partial response of the tumor to treatment, but also the removal of these patients from the category of incurable ones. The article describes a new rare type of BRAF::EPB41L2 gene fusion detected in a piloid astrocytoma that developed in the posterior cranial fossa in an 11-year-old boy.

Over the past decade, next generation sequencing (NGS) has become the standard method in research of cancer genomics; currently NGS is entering a new stage - direct usage in clinical oncology to improve diagnostics and establish personalized tumor treatments. NGS allows to read the genome and it is successfully applied to detect mutations and other somatic changes (translocations, inversions, insertions and deletions, copy number variants) leading to the development of a tumor. With a focus on transcriptome sequencing allows to clearly identify differences in gene expression, improve the classification of tumors and detect somatic chimeras. All these possibilities are especially relevant for pediatric neurooncology filed in view of the existing limitations in treatment and the need for the most accurate identification of the key factors of tumor development. In this article, we describe sequencing technology basis, its application on brain tumor materials to improve diagnostics, and other relevant possibilities that can be considered for direct usage in medicine.

Here we report three patients with rare primary intracranial sarcomas, two of them were CIC-sarcomas and one was a DICER1 -sarcoma. Tumors were examined using DNA methylation. It is important to study of CIC fusions and DICER1 mutations in malignant brain tumors.

Glioma metastasis outside the central nervous system is a quite rare phenomenon. The disease in a young woman manifested itself as back pain and loss of vision in the left eye. Magnetic resonance imaging (MRI) revealed a tumor of the optic nerve; positron emission tomography showed multiple secondary bone changes. At the same time, MRI detected no signs of neoplasm in the midline brain structures (the brain stem and subcortical nuclei) and spinal cord. Two biopsies (superior iliac spine trephine biopsy and optic nerve tumor biopsy) were performed. There were similar histological tumors; the optic nerve tumor was found to have K27M mutation in the H3F3A gene, whereas the metastatic tumor lacked this mutation (possibly due to the quality and quantity of DNA isolated from the tumor cells). The interesting features of this case are the simultaneous detection of primary and metastatic tumors before receiving any treatment and the absence of the K27M mutation in the H3F3A gene in the metastasis.

The paper describes a clinical case of atypical teratoid/rhabdoid tumor with preserved INI1 expression and SMARCA4 gene mutations in an 8-month-old girl. Genome-wide DNA methylation, hierarchical clustering, and next-generation sequencing were used to make a tumor diagnosis. However, BRG1 immunohistochemical examination may be recommended in the routine practice of diagnosis and study of childhood CNS malignant tumors.

In most cases, oncogene amplification are prognostic and predictive markers for various tumors, therefore DNA probes are unable to reveal changes in the copy numbers should not be used to diagnose malignant tumors., Objective: To comparatively analyze DNA probes from different manufacturers to detect MYC gene amplification in routine practice., Material and Methods: The study material was formalin-fixed paraffin-embedded medulloblastoma fragments from 4 patients, with discrepancies in the results in the detection of MYC gene amplification., Results: MYC gene amplification was determined using DNA probes: Kreatech MYC (8q24)/SE 8, Vysis LSI MYC SO, Vysis CEP 8 (D8Z2) SG, and Zytolight SPEC MYC/CEN 8 Dual Color Probe. The use of the probes Kreatech TERC (3q26)/MYC (8q24)/SE7 Triple-Color probe failed to detect MYC gene amplification; this probe showed a balanced profile of chromosome 8., Conclusion: In routine practice, fluorescence in situ hybridization with the DNA probes Kreatech MYC (8q24)/SE 8, Vysis LSI MYC SO, Vysis CEP 8 (D8Z2) SG and Zytolight SPEC MYC/CEN 8 Dual Color Probe can be the method of choice for studying the copy number of the MYC gene. However, the authors strongly recommend that the Kreatech TERC (3q26)/MYC (8q24)/SE7 Triple-Color should not be used for this purpose. In addition, probes for fluorescence in situ hybridization must be necessarily tested in large reference laboratories dealing with one or another area of oncopathology.

Objective: To comprehensively assess the functional molecular biological status of different tumor cell populations in glioblastoma samples., Material and Methods: The activity of Ki-67, Bcl-2, and BCL6 expression was determined in 20 tumor samples from patients with glioblastoma. After that, a spatial analysis of heterogeneity in the expression of these markers in different tumor cell populations was carried out using computer and software tools and calculating the percentage of cells (PC) expressing this marker (Ki-67 labeling index (LI)) and a modified histoscore in different cell clusters., Results: Analysis of heterogeneity in the distribution of Ki-67, Bcl-2, and BCL6 expression could identify five cell clusters differing in the expression level of the above-mentioned markers. The most active cluster was the perivascular one (the highest mean Ki-67 LI (22.23±1.4%) and histoscore (118.59±3.36%); BCL6 PC and histoscore (17.4±1.4 and 79.32±4.86%, respectively). The least proliferative activity was observed in the perinecrotic cluster (Ki-67 LI (6.83±0.5%) and histoscore (62.46±2.25%)), while the neighboring transient necrotic cluster displayed sufficiently active proliferative processes (Ki-67 LI (18.39±0.56%) and histoscore (112.65±2.76%)). In addition, the transient vascular cluster was noted for a low proliferative activity (Ki-67 LI (8.37±0.35%) and histoscore (75.48±2.04%)). Finally, the intermediate cluster was characterized by the mean values of all parameters (Ki-67 LI (10.68±0.39%) and histoscore (95.73±2.37%). It should be noted that the differences in the expression activity for markers in these clusters were statistically significant., Conclusion: The perivascular cluster carries the greatest potential for tumor progression and recurrence, which agrees with the data available in the literature: the perivascular zone is the most important niche for glioma stem cells that make a considerable contribution to the malignant potential of glioblastoma. Tumor pathogenesis and morphogenesis are a complex interweaving of interrelated factors, the realization of which within the framework of a multi-level heterochronic pathological process leads to the segregation of tumor cells and to the appearance of separate cell populations described in this paper.

Unlabelled: Glioblastoma is the most common primary malignant glial tumor of the brain in adult patients., Aim: to define the prognostic value of isocitrate dehydrogenase-1 (IDH-1) mutation and methylguanine-DNA methyltransferase (MGMT) methylation status in patients with glioblastoma (GB) and to analyze the impact of clinical data (gender, age, and tumor site), histological variants of the tumor structure, and time to development of recurrences on the course of the disease., Subjects and Methods: The investigation enrolled 63 GB patients aged 18 to 71 years who had received combined treatment (surgery, chemo- and radiotherapy) at the N.I. Burdenko Research Institute of Neurosurgery, Ministry of Health of the Russian Federation, in the period 2008 to 2011. The investigators performed a morphological examination of all tumor tissue samples and an immunohistochemical examination using anti-IDH-1 R-132 antibody clone («Dianova», Germany) and defined MGMT methylation status by a polymerase chain reaction using the CpGenome DNA Modification Kit («Chemicon International», USA). The data were statistically processed using a package of Statistica 6.0 programs., Results: Patient age, time to development of recurrent glioblastoma, mutations in the IDH-1 gene and MGMT were found to be prognostic factors for overall survival among adult patients in this category., Conclusion: Analysis of clinical findings and identification of molecular genetic aberrations in the tumor cells will be able to elaborate an individual approach to treating patients with glioblastoma in order to increase their survival rates and to improve quality of life.