Newly recognised Tumour Types in Glioneuronal tumours according to the 5th edition of the CNS WHO Classification

Abstract

Summary Glioneuronal tumours (GNT) are uncommon neoplasms, characterised by glial and neuronal differentiation. In the 5th edition of the World Health Organization (WHO) Classification, they are grouped under the heading “Glioneuronal and neuronal tumours”, which comprises fourteen different tumours, among which the diffuse glioneuronal tumour with oligodendroglioma-like cells and nuclear clusters (DGONC), myxoyd glioneuronal tumour (MGT) and multinodular and vacuolating neuronal tumour (MNVNT) are new types. MGT and MNVNT are classified WHO grade 1 and may be recognised and diagnosed by peculiar clinical-pathological features. DGONC was not assigned a WHO grade and was only provisionally included among GNT, due to the possibility that it rather represents an embryonal tumour type or subtype. Although the histopathological characteristics may be useful for its identification, the specific methylation profile is an essential diagnostic criterion for DGONC.

Pediatric CNS tumors and 2021 WHO classification: what do oncologists need from pathologists?

“…Ki-67 is frequently low (<1%). CD34 expression may be observed in ramified neural elements and GFAP-positive reactive astrocytes of the adjacent cortex ( Barresi et al, 2022 ). Molecular analyses may reveal MAPK pathway-activating abnormalities.…”

“…Due to the low number of cases with an available follow-up, DGONC was not assigned to a CNS WHO grade. To date, outcome data are only available for 26 patients, indicating a 5-year progression-free survival rate equal to 81% and 5-year overall survival rate equal to 89% ( Barresi et al, 2022 ). Myxoid glioneuronal tumour (MGT) represents a newly introduced entity, which is located in septum pellucidum and deep periventricular white matter and classified as CNS WHO grade 1 due to its favorable outcome ( Bale and Rosenblum, 2022 ).…”

New perspectives: Glioma in adult patients

“…8 With the WHO 2021 classification, some entities we previously worked with (e.g., gliomatosis) disappeared and new entities, often very rare, appeared (Table 1). 9 The cornerstone of the new classification is isocitrate dehydrogenase (IDH) mutation. The identification of this mutation allows the subdivision of glial tumors into IDH mutant and wild-type neoplasms with very different biological and clinical characteristics.…”

“…With the WHO 2021 classification, some entities we previously worked with (e.g., gliomatosis) disappeared and new entities, often very rare, appeared (Table 1). 9…”

Introduction

“…Bertero et al 4 report the advances in the classification of ependymal neoplasms, which merging anatomic, histologic, immunohistochemical, sequencing, and methylation profiling has significantly improved the prognostic stratification of patients harboring such neoplasms. Barresi et al 5 illustrate the new entities which expand the large group of glioneuronal and neuronal tumors. Such new entities include the diffuse glioneuronal tumor with oligodendroglioma-like cells and nuclear clusters (DGONC), myxoyd glioneuronal tumor (MGT) and multinodular and vacuolating neuronal tumour (MNVNT).…”