* **Clinical Presentation**: Seizures, headaches, focal neurological deficits, cognitive decline.
  * **Imaging**:
    * MRI with contrast (gold standard).
    * Advanced techniques: perfusion, spectroscopy, DTI, fMRI.
  * **Histopathology**:
    * Stereotactic biopsy or resection sample.
  * **Molecular Classification (WHO 2021)**:
    * IDH mutation status (IDH-mutant vs. IDH-wildtype).
    * 1p/19q codeletion (for oligodendrogliomas).
    * ATRX, TP53, MGMT methylation, EGFR amplification, TERT promoter mutation.