Glial and glioneuronal tumors: Navigating the complexity of evolving concepts and new classification

Area of Science:

• Neuropathology
• Oncology
• Genetics

Background:

• The 2021 World Health Organization (WHO) CNS5 classification represents a significant shift in central nervous system tumor diagnostics.
• This new standard integrates morphological and molecular data, impacting tumor classification and therapy.
• Previous classifications relied primarily on histology, necessitating an update to incorporate recent molecular discoveries.

Purpose of the Study:

• To provide an overview of the evolving concepts in glial and glioneuronal tumors under the WHO CNS5.
• To explain the rationale behind the substantial changes in tumor classification introduced by WHO CNS5.
• To offer a roadmap for navigating the complexities of glial and glioneuronal tumors within the new WHO CNS5 framework.

Main Methods:

• Review and synthesis of the WHO CNS5 classification criteria for central nervous system tumors.
• Analysis of the specific changes impacting glial and glioneuronal tumor classification.
• Explanation of the integration of molecular markers alongside traditional histopathology.

Main Results:

• WHO CNS5 introduces novel tumor entities and reclassifies existing ones, particularly within glial and glioneuronal categories.
• The classification emphasizes a multi-modal diagnostic approach combining morphology and molecular features.
• Significant conceptual shifts have occurred, demanding adaptation in diagnostic and therapeutic strategies.

Conclusions:

• The WHO CNS5 classification necessitates a comprehensive understanding of integrated diagnostic criteria for accurate brain tumor diagnosis.
• Clinical practice faces challenges in adopting the new system, particularly regarding molecular testing and interpretation.
• This work aims to facilitate the integration of WHO CNS5 guidelines for glial and glioneuronal tumors into routine neuropathology.