Embryonal Tumors of the Central Nervous System: An Update

Intraoperative Touch Imprint Cytology of Brain Neoplasms: A Useful High-Diagnostic Tool in 93 Consecutive Cases; Differential Diagnoses, Pitfalls, and Traps

Introduction

Intraoperative cytological examination of central nervous system (CNS) lesions was first introduced in 1920 by Eisenhardt and Cushing for rapid evaluation of neurosurgical specimens and to guide surgical treatment. It is recognized that this method not only confirms the adequacy of biopsy in CNS samples but also indicates the presence and preliminary diagnosis of lesional tissue.

Methods

A total of 93 patients who underwent touch imprint cytology (TIC) for CNS tumors or lesions between 2018 and 2023 were included in the study. All cases were correlated with the final histopathological diagnosis, and pitfalls and difficulties encountered with discrepancies were noted.

Result

The most common primary CNS tumors were gliomas and meningiomas, while secondary (metastatic) tumors were predominantly lung, breast, and gastrointestinal system carcinomas. Sensitivity, specificity, positive predictive value, and negative predictive value for diagnosis with TIC were 94.1%, 100%, and 61.5%, respectively. Final histopathological diagnosis by TIC was made in 88 cases (94.6%) and the discrepancy was found in 5 cases (5.37%). Three of the five discrepancies (3.2%) were haematolymphoid malignancies (two lymphomas and one plasma cell neoplasia), one glioblastoma, and one hemangioblastoma case.

Conclusion

TIC is a fast, safe, and inexpensive diagnostic tool used during intraoperative neuropathology consultation. Awareness of the pitfalls of using this method during intraoperative consultation will enable high-diagnostic accuracy.

Embryonal Tumors of the Central Nervous System with Multilayered Rosettes and Atypical Teratoid/Rhabdoid Tumors

The 2016 WHO classification of tumors of the central nervous system affected importantly the group of CNS embryonal tumors. Molecular analysis on methylome, genome, and transcriptome levels allowed better classification, identification of specific molecular hallmarks of the different subtypes of CNS embryonal tumors, and their more precise diagnosis. Routine application of appropriate molecular testing and standardized reporting are of pivotal importance for adequate prognosis and treatment, but also for epidemiology studies and search for efficient targeted therapies. As a result of this approach, the term primitive neuroectodermal tumor-PNET was removed and a new clinic-pathological entity was introduced-Embryonal tumor with multilayered rosettes (ETMR). The group of CNS embryonal tumors include also medulloblastoma, medulloepithelioma, CNS neuroblastoma, CNS ganglioneuroblastoma, atypical teratoid/rhabdoid tumor (ATRT) and their subtypes. This chapter will focus mainly on ETMR and ATRT. Embryonal tumors with multilayered rosettes and the atypical teratoid/rhabdoid tumors are undifferentiated or poorly differentiated tumors of the nervous system that originate from primitive brain cells, develop exclusively in childhood or adolescence, and are characterized by a high degree of malignancy, aggressive evolution and a tendency to metastasize to the cerebrospinal fluid. Their clinical presentation is similar to other malignant, intracranial, neoplastic lesions and depends mainly on the localization of the tumor, the rise of the intracranial pressure, and eventually the obstruction of the cerebrospinal fluid pathways. The MRI image characteristics of these tumors are largely overlappingintra-axial, hypercellular, heterogeneous tumors, frequently with intratumoral necrosis and/or hemorrhages. Treatment options for ETMR and ATRT are very restricted. Surgery can seldom achieve radical excision. The rarity of the disease hampers the establishment of a chemotherapy protocol and the usual age of the patients limits severely the application of radiotherapy as a therapeutic option. Consequently, the prognosis of these undifferentiated, malignant, aggressive tumors remains dismal with a 5-year survival between 0 and 30%.

Primary Leptomeningeal Medulloblastoma in Adults: A Diagnostic Challenge-Case Report and Systematic Review

Primary leptomeningeal medulloblastoma (PL-MB) in adults is a rare disease with a severe prognosis. A 35-year-old woman presented with headaches, diplopia, and gait ataxia, with triventricular hydrocephalus and descent of the cerebellar tonsils beyond the foramen magnum. Endoscopic third ventriculostomy was performed. Six months later, headaches recurred. Dilatation of the supratentorial ventricular system and massive cerebellar swelling without contrast-enhancing nodularities were reported. Occipitocervical decompression with duraplasty was performed. A bioptic diagnosis of PL-MB was made. Craniospinal irradiation and chemotherapy were administered. After 18 months, no recurrence was observed. Few cases of PL-MB have been reported: patients die before treatment or within a few days after surgery. Our long-term survival could be ascribable to a slow clinical presentation and an early diagnosis that allowed surgical treatment and the administration of a combined chemoradiotherapy protocol. Cerebellar swelling, even without associated enhancing lesions, with or without hydrocephalus, should be a neuroradiological alarm sign, and PL-MB should be considered.

Progress on the study of the anticancer effects of artesunate

Artesunate (ART) is a derivative of artemisinin that is extracted from the wormwood plant Artemisia annua. ART is an antimalarial drug that has been shown to be safe and effective for clinical use. In addition to its antimalarial properties, ART has been attracting attention over recent years due to its reported inhibitory effects on cancer cell proliferation, invasion and migration. Therefore, ART has a wider range of potential clinical applications than first hypothesized. The aim of the present review was to summarize the latest research progress on the possible anticancer effects of ART, in order to lay a theoretical foundation for the further development of ART as a therapeutic option for cancer.

Optical genome mapping identifies a germline retrotransposon insertion in SMARCB1 in two siblings with atypical teratoid rhabdoid tumors

In a subset of pediatric cancers, a germline cancer predisposition is highly suspected based on clinical and pathological findings, but genetic evidence is lacking, which hampers genetic counseling and predictive testing in the families involved. We describe a family with two siblings born from healthy parents who were both neonatally diagnosed with atypical teratoid rhabdoid tumor (ATRT). This rare and aggressive pediatric tumor is associated with biallelic inactivation of SMARCB1, and in 30% of the cases, a predisposing germline mutation is involved. Whereas the tumors of both siblings showed loss of expression of SMARCB1 and acquired homozygosity of the locus, whole exome and whole genome sequencing failed to identify germline or somatic SMARCB1 pathogenic mutations. We therefore hypothesized that the insertion of a pathogenic repeat‐rich structure might hamper its detection, and we performed optical genome mapping (OGM) as an alternative strategy to identify structural variation in this locus. Using this approach, an insertion of ~2.8 kb within intron 2 of SMARCB1 was detected. Long‐range PCR covering this region remained unsuccessful, but PacBio HiFi genome sequencing identified this insertion to be a SINE‐VNTR‐Alu, subfamily E (SVA‐E) retrotransposon element, which was present in a mosaic state in the mother. This SVA‐E insertion disrupts correct splicing of the gene, resulting in loss of a functional allele. This case demonstrates the power of OGM and long‐read sequencing to identify genomic variations in high‐risk cancer‐predisposing genes that are refractory to detection with standard techniques, thereby completing the clinical and molecular diagnosis of such complex cases and greatly improving counseling and surveillance of the families involved. © 2021 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.

MiRNAs in early brain development and pediatric cancer: At the intersection between healthy and diseased embryonic development

The size and organization of the brain are determined by the activity of progenitor cells early in development. Key mechanisms regulating progenitor cell biology involve miRNAs. These small noncoding RNA molecules bind mRNAs with high specificity, controlling their abundance and expression. The role of miRNAs in brain development has been studied extensively, but their involvement at early stages remained unknown until recently. Here, recent findings showing the important role of miRNAs in the earliest phases of brain development are reviewed, and it is discussed how loss of specific miRNAs leads to pathological conditions, particularly adult and pediatric brain tumors. Let-7 miRNA downregulation and the initiation of embryonal tumors with multilayered rosettes (ETMR), a novel link recently discovered by the laboratory, are focused upon. Finally, it is discussed how miRNAs may be used for the diagnosis and therapeutic treatment of pediatric brain tumors, with the hope of improving the prognosis of these devastating diseases.

Pineal Gland Tumors: A Review

Simple Summary

Pineal neoplasms are tumors with different and variable morphological, histological, and radiological characteristics and, consequently different diagnosis and management. Due to their rarity, pineal tumors may be misdiagnosed. Pineal tumors, are divided into germ cell tumors, pineal parenchymal tumors and tumors that derive from adjacent structures. In this review, we report the clinical relevance of the main pineal gland tumors, underlining the importance of studying the triggering causes of pineal region carcinogenesis, to realize appropriate diagnosis and, consequently, better clinical management.

Abstract

The pineal gland is a small, pinecone-shaped endocrine gland that participates in the biological rhythm regulation of vertebrates. The recognized major product of the pineal gland is melatonin—a multifunctional endogenous indoleamine. Accumulating evidence suggests that the pineal gland is important for preserving ideal health conditions in vertebrate. Tumors of the pineal region account for approximately 3–11% of pediatric brain neoplasms but fewer than 1% of brain neoplasms in adults. It is fundamental to expand advanced imaging techniques together with both clinical and laboratory knowledge, to help to differentiate among pineal neoplasms and thus facilitate accurate primary diagnoses and proper therapeutic interventions. In this review, we report the gross anatomy of the pineal gland and its functional significance and discuss the clinical relevance of pineal gland tumors, underlining the importance of identifying the leading causes of pineal region masses.

Medulloblastoma-associated mutations in the DEAD-box RNA helicase DDX3X/DED1 cause specific defects in translation

Medulloblastoma is the most common pediatric brain cancer, and sequencing studies identified frequent mutations in DDX3X, a DEAD-box RNA helicase primarily implicated in translation. Forty-two different sites were identified, suggesting that the functional effects of the mutations are complex. To investigate how these mutations are affecting DDX3X cellular function, we constructed a full set of equivalent mutant alleles in DED1, the Saccharomyces cerevisiae ortholog of DDX3X, and characterized their effects in vivo and in vitro. Most of the medulloblastoma-associated mutants in DDX3X/DED1 (ded1-mam) showed substantial growth defects, indicating that functional effects are conserved in yeast. Further, while translation was affected in some mutants, translation defects affecting bulk mRNA were neither consistent nor correlated with the growth phenotypes. Likewise, increased formation of stress granules in ded1-mam mutants was common but did not correspond to the severity of the mutants' growth defects. In contrast, defects in translating mRNAs containing secondary structure in their 5' untranslated regions (UTRs) were found in almost all ded1-mam mutants and correlated well with growth phenotypes. We thus conclude that these specific translation defects, rather than generalized effects on translation, are responsible for the observed cellular phenotypes and likely contribute to DDX3X-mutant medulloblastoma. Examination of ATPase activity and RNA binding of recombinant mutant proteins also did not reveal a consistent defect, indicating that the translation defects are derived from multiple enzymatic deficiencies. This work suggests that future studies into medulloblastoma pathology should focus on this specific translation defect, while taking into account the wide spectrum of DDX3X mutations.

Updates in Pediatric Glioma Pathology

Gliomas are a diverse group of primary central nervous system tumors with astrocytic, oligodendroglial, and/or ependymal features and are an important cause of morbidity/mortality in pediatric patients. Glioma classification relies on integrating tumor histology with key molecular alterations. This approach can help establish a diagnosis, guide treatment, and determine prognosis. New categories of pediatric glioma have been recognized in recent years, due to increasing application of molecular profiling in brain tumors. The aim of this review is to alert pediatric pathologists to emerging diagnostic concepts in pediatric glioma neuropathology, emphasizing the incorporation of molecular features into diagnostic practice.