WHO grading
Pronunciation: W-H-O grading
Also written as: WHO — World Health Organization grading
The World Health Organization classification system for brain tumors based on histological features and molecular markers.
Full Definition
A standardized international system for classifying central nervous system tumors on a scale from Grade I (least aggressive) to Grade IV (most aggressive). The WHO grading system combines traditional histological criteria with increasingly important molecular markers to provide more precise tumor classification. Grade I tumors are typically benign with excellent prognosis after complete resection, while Grade IV tumors are highly malignant with poor outcomes. The 2021 WHO Classification emphasizes integrated diagnosis incorporating both morphology and molecular features.
Usage
Usage note: Always use Roman numerals (I-IV) for grades; distinguish from cancer staging systems.
In Context
- "The tumor was assigned WHO Grade II based on increased cellularity without necrosis." — pathology report
- "WHO grading remains the gold standard for brain tumor classification." — medical textbook