Identify the modern WHO CNS glioma grade by integrating histologic findings with IDH and codeletion markers.
Guidelines & Evidence
Clinical Details
Section 1
When to Use
When to Use
Interpreting pathology reports for adult diffuse gliomas.
Setting patient and family prognostic expectations based on the modern molecular hierarchy of brain tumors.
Section 2
Formula & Logic
The IDH Switch
In the 2021 WHO classification, molecular markers trump histological appearance. Isocitrate Dehydrogenase (IDH) mutation status is the master switch. An IDH-wildtype tumor is fundamentally distinct from an IDH-mutant tumor, even if they look identical under the microscope.
1p/19q Codeletion
Loss of heterozygosity at chromosomes 1p and 19q defines an Oligodendroglioma. If present alongside an IDH mutation, it predicts an extraordinarily robust response to alkylating chemotherapy (like PCV or Temozolomide) and significantly prolonged survival.
Section 3
Evidence Appraisal
Primary Reference
The 2021 WHO Classification of Tumors of the Central Nervous System: a summary
Louis DN et al. • Neuro-oncology. 2021;23(8):1231-1251
