WHO grading
Also written as: WHO — World Health Organization
The World Health Organization classification system for brain tumors based on histological features and molecular markers.
Full Definition
WHO grading is the internationally accepted classification system for central nervous system tumors developed by the World Health Organization. The system assigns grades I through IV based on histological features such as cellularity, nuclear atypia, mitotic activity, microvascular proliferation, and necrosis, along with increasingly important molecular markers. Grade I represents benign tumors with excellent prognosis, Grade II indicates low-grade malignancy, Grade III denotes anaplastic/high-grade tumors, and Grade IV represents the most aggressive malignancies. The 2021 WHO Classification significantly incorporated molecular features, making integrated diagnoses that combine histology and molecular findings mandatory for many tumor types. This grading system is crucial for determining prognosis, treatment selection, and clinical trial eligibility.
Usage
Usage note: Always specify which WHO edition when citing classifications.
In Context
- "The final diagnosis incorporated both histological and molecular features according to WHO grading criteria." — Pathology report
- "Treatment protocols are primarily determined by WHO grading and molecular subtype." — Treatment planning