UNASSIGNED: The association between primary brain tumors, such as glioneuronal tumors, with autosomal-dominant polycystic kidney disease (ADPKD) remains poorly understood, with only two cases reported excluding this one. This case of an ADPKD patient diagnosed with a rosette-forming glioneuronal tumor highlights an exceptionally rare potential association warranting further investigation.
UNASSIGNED: A 28-year-old male with ADPKD presented with progressive ataxia, dizziness, and headache. MRI revealed a cerebellar mass and obstructive hydrocephalus. Surgical resection and histopathological examination confirmed the diagnosis of a rosette-forming glioneuronal tumor. Postoperatively, the patient showed significant symptom improvement.
UNASSIGNED: The interplay between genetics and glioneuronal development is complex and underexplored. While most glioneuronal arise sporadically, rare genetic syndromes may predispose individuals to these tumors. Additionally, although more than 70 cases of ADPKD with concurrent tumors were reported, the literature on this specific association remains limited.
UNASSIGNED: This case underscores the need for heightened awareness of potential associations between ADPKD and tumors such as glioneuronal tumors. With limited literature on this subject, further research is imperative to understand the underlying mechanisms and clinical implications. Enhancing our knowledge in this area can improve patient outcomes and management strategies.

Glioneuronal tumors (GNTs) are an expanding group of primary CNS neoplasms, commonly affecting children, adolescents and young adults. Most GNTs are relatively indolent, low-grade, WHO grade I lesions. In the pediatric age group, GNTs have their epicenter in the cerebral cortex and present with seizures. Alterations in the mitogen-activated protein kinase (MAPK) pathway, which regulates cell growth, are implicated in tumorigenesis. Imaging not only plays a key role in the characterization and pre-surgical evaluation of GNTs but is also crucial role in follow-up, especially with the increasing use of targeted inhibitors and immunotherapies. In this chapter, we review the clinical and imaging perspectives of common pediatric GNTs.

The World Health Organization (WHO) published the 5th edition classification of tumors of central nervous system in 2021, commonly abbreviated as WHO CNS5, which became the new standard for brain tumor diagnosis and therapy. This edition dramatically impacted tumor diagnostics. In short it introduced new tumors, changed the names of previously recognized tumors, and modified the working definition of previously known tumors. The new system appears complex due to the integration of morphological and multiple molecular criteria. The most radical changes occurred in the field of glial and glioneuronal tumors, which constitutes the lengthy first chapter of this new edition. Herein we present an illustrative outline of the evolving concepts of glial and glioneuronal tumors. We also attempt to explain the rationales behind this substantial change in tumor classification and the challenges to update and integrate it into clinical practice. We aim to present a concise and precise roadmap to aid navigation through the intricate conceptual framework of glial and glioneuronal tumors in the context of WHO CNS5.

BACKGROUND: Methylation analysis has become a powerful diagnostic tool in modern neurooncology. This technique is valuable to diagnose new brain tumor types.
OBJECTIVE: To describe the MRI and histological pattern of neuroepithelial tumor with PLAGL1 gene fusion.
METHODS: We present a 6-year-old patient with small right frontal intraaxial tumor causing drug resistant epilepsy. Despite indolent preoperative clinical course and MRI features suggesting glioneuronal tumor, histological evaluation revealed characteristics of high-grade glioma, ependymoma and neuroblastoma.
RESULTS: Methylation analysis of tumor DNA confirmed a new type of a recently discovered neoplasm - neuroepithelial tumor with PLAGL1 fusion (NET PLAGL1). PCR confirmed fusion of PLAGL1 and EWSR1 genes. No seizures were observed throughout the follow-up period. There was no tumor relapse a year after surgery.
CONCLUSIONS: Methylation analysis in neurooncology is essential for unclear tumor morphology or divergence between histological and clinical data. In our case, this technique confirmed benign nature of tumor, and we preferred follow-up without unnecessary adjuvant treatment.
Определение метиляционного профиля генома опухоли становится значимым способом диагностики новообразований центральной нервной системы. На основании этой методики также возможно выявлять новые классы опухолей головного мозга.
UNASSIGNED: Описать результаты магнитно-резонансной томографии (МРТ) и гистологическую картину нейроэпителиальной опухоли со слиянием гена PLAGL1.
UNASSIGNED: Представлено клиническое наблюдение ребенка 6 лет с внутримозговой опухолью лобной доли и фармакорезистентной эпилепсией. По рентгенологическим характеристикам, до операции предполагалась доброкачественная глионейрональная опухоль, однако гистология соответствовала новообразованию, имевшему черты злокачественной глиомы, эпендимомы и нейробластомы.
UNASSIGNED: Проведен метиляционный анализ ткани опухоли, показавший, что она относится к недавно описанному новому классу — «нейроэпителиальная опухоль со слиянием гена PLAGL1». Тест полимеразной цепной реакции подтвердил слияние генов PLAGL1 и EWSR1. После операции отмечено прекращение приступов, спустя 1 год на МРТ рецидива опухоли не определялось.
UNASSIGNED: Метиляционный анализ в нейроонкологии играет решающую роль в случаях неоднозначной морфологии опухоли, расхождения ее гистологической и клинико-рентгенологической картины. В приведенном клиническом примере стало возможным доказать доброкачественный характер опухоли и выбрать выжидательную тактику, избежав адъювантного лечения у ребенка.

An unusual, small cell-predominant, high-grade glioneuronal tumor in the occipital lobe of a 49-year-old man that co-existed with a low-grade tumor is reported. The tumor consisted of two distinct components: the major component was a dense proliferation of primitive small cells showing bidirectional neuronal and glial differentiation; and the minor component consisted of a proliferation of well-differentiated astrocytes intermingled with mature neuronal cells. In the former component, perivascular pseudorosette-like or pseudopapillary growth reminiscent of ependymoma or papillary glioneuronal tumor (PGNT), respectively, was prominent, and hypertrophic astrocytic cells were located just outside the central blood vessels. Small cells were immunoreactive for Olig2, synaptophysin, and, less frequently, for glial fibrillary acidic protein. The low-grade component included Rosenthal fibers, hemosiderin deposition, and perivascular lymphocytic infiltration, thus closely resembling ganglioglioma. Cytogenetic studies did not demonstrate any mutations or rearrangements of the genes IDH1, IDH2, H3F3A, BRAF, FGFR1, or TERT promoter. The tumor recurred and spread along the ventricular surface three years after total removal. The small cell-predominant, high-grade component was considered to have evolved from the ganglioglioma-like, low-grade component. The histopathologic resemblance of the high-grade component to PGNT was a special feature.

Papillary glioneuronal tumors are rare neoplasm, accounting only <0.02% of all intracranial tumors. They are generally low grade usually occur in the temporal lobe near the third ventricle. We report an extremely rare case of intraventricular tumor with a high proliferation index. CD 117 expression found in our case is the first study to the best of our knowledge to be described in these tumors. The clinical and diagnostic significance of this finding is subject to further studies.

Glioneuronal and neuronal tumors (GNTs) are rare neoplasms composed of neural and glial elements frequently located in the temporal lobe. Epilepsy is the main symptom and diagnosis mostly occurs before adulthood. The great majority of GNTs are WHO grade I tumors, but anaplastic transformations and forms exist. Their common association with focal cortical dysplasia is well recognized and should be taken into consideration during neurophysiological presurgical and surgical planning since the aim of surgery should be the removal of the tumor and of the entire epileptogenic zone according to anatomo-electrophysiological findings. Surgery still remains the cornerstone of symptomatic GNT, while radiotherapy, chemotherapy, and new target therapies are generally reserved for anaplastic, unresectable, or evolving tumors. Furthermore, since many GNTs show overlapping clinical and neuroradiological features, the definition of specific histopathological, genetic, and molecular characteristics is crucial. Epileptological, oncological, neurosurgical, and pathological issues of these tumors make a multidisciplinary management mandatory.

Glioneuronal tumors are a heterogenous group of CNS neoplasms that can be challenging to accurately diagnose. Molecular methods are highly useful in classifying these tumors-distinguishing precise classes from their histological mimics and identifying previously unrecognized types of tumors. Using an unsupervised visualization approach of DNA methylation data, we identified a novel group of tumors (n = 20) that formed a cluster separate from all established CNS tumor types. Molecular analyses revealed ATRX alterations (in 16/16 cases by DNA sequencing and/or immunohistochemistry) as well as potentially targetable gene fusions involving receptor tyrosine-kinases (RTK; mostly NTRK1-3) in all of these tumors (16/16; 100%). In addition, copy number profiling showed homozygous deletions of CDKN2A/B in 55% of cases. Histological and immunohistochemical investigations revealed glioneuronal tumors with isomorphic, round and often condensed nuclei, perinuclear clearing, high mitotic activity and microvascular proliferation. Tumors were mainly located supratentorially (84%) and occurred in patients with a median age of 19 years. Survival data were limited (n = 18) but point towards a more aggressive biology as compared to other glioneuronal tumors (median progression-free survival 12.5 months). Given their molecular characteristics in addition to anaplastic features, we suggest the term glioneuronal tumor with ATRX alteration, kinase fusion and anaplastic features (GTAKA) to describe these tumors. In summary, our findings highlight a novel type of glioneuronal tumor driven by different RTK fusions accompanied by recurrent alterations in ATRX and homozygous deletions of CDKN2A/B. Targeted approaches such as NTRK inhibition might represent a therapeutic option for patients suffering from these tumors.

BACKGROUND: Intracranial hemorrhage is extremely rare during the initial stages of glioma. Here, we report a case of glioma with unclassified pathology and intracranial bleeding.
METHODS: After the second surgery for intracerebral hemorrhage, the patient experienced weakness in the left arm and leg, but could walk unassisted. One month after discharge, the weakness in the left limbs had exacerbated and the patient also suffered from headaches and dizziness. A third surgery was ineffective against the rapidly growing tumor. Intracerebral hemorrhage may be the initial symptom of glioma in some rare cases, and atypical perihematomal edema can be used for diagnosis during an emergency. Certain histological and molecular features seen in our case were similar to that of glioblastoma with a primitive neuronal component, which is termed diffuse glioneuronal tumor with features similar to oligodendroglioma and nuclear clusters (DGONC). The patient underwent three surgeries to remove the tumor. The first tumor resection had been performed when the patient was 14-years-old. Resection of the hemorrhage and bone disc decompression were performed when the patient was 39-years-old. One month after the last discharge, the patient underwent neuronavigation-assisted resection of the right frontotemporal parietal lesion plus extended flap decompression. On the 50th d after the third operation, computed tomography imaging showed rapid tumor growth accompanied by brain hernia. The patient was discharged and died 3 d later.
CONCLUSIONS: Glioma can present as bleeding in the initial stage and should be considered in such a setting. We have reported a case of DGONC, which is a rare molecular subtype of glioma with a unique methylation profile.

Polymorphous low-grade neuroepithelial tumor of the young (PLNTY), one of the pediatric-type diffuse low-grade gliomas, is characterized by a diffuse infiltrating pattern of oligodendroglioma-like tumor cells showing CD34 positivity and harbors mitogen-activated protein kinase (MAPK) alteration, such as vRAF murine sarcoma viral oncogene homolog B1 (BRAF) p.V600E or fibroblast growth factor fusion genetically. It occurs mainly in pediatric and adolescents with seizures due to the dominant location of the temporal lobe. However, there have been a few cases of PLNTY in adult patients, suggesting the wide range of this tumor spectrum. Here, we describe two cases of PLNTY, one in a 14-year-old female and the other in a 66-year-old female. The pediatric tumor showed typical clinical course and histopathology with BRAF p.V600E mutation, whereas the elderly tumor was unusual because of non-epileptic onset clinically and ependymal differentiation histopathologically harboring KIAA1549-BRAF fusion. There might be unusual but possible PLNTY, as in our elderly case. We also compared typical pediatric and unusual elderly tumors by reviewing the literature.