WHO Classification of CNS Tumors

What it is

The WHO Classification of Tumors of the Central Nervous System is the internationally used standard system for naming, grouping, and grading tumors of the brain and spinal cord — including gliomas. It provides a common framework that guides diagnosis, treatment decisions, and research worldwide.

Understanding WHO Classification of CNS Tumors

Developed and periodically updated by the World Health Organization, this classification defines the recognized tumor types, organizes them into groups, and assigns grades reflecting expected behavior. For gliomas, it specifies how each type is defined and graded. The classification is regularly revised as scientific understanding advances; the current edition, published in 2021 and often called "WHO CNS5," represents a major shift by integrating molecular (genetic) features alongside the traditional microscope-based (histological) features. Because the classification is used internationally, it ensures that a given diagnosis means the same thing across hospitals and countries, supporting consistent care and research. Understanding the WHO Classification clarifies the framework behind every glioma diagnosis. Understanding this system clarifies how gliomas are formally defined and graded.

Why it matters

Understanding the WHO Classification helps patients and families see that there is an internationally agreed framework behind their diagnosis — ensuring a glioma is defined and graded consistently, which guides treatment and research.