Brain Tumor Grading System | Johns Hopkins Comprehensive Brain Tumor Center

A pathologist will examine a patient’s biopsy sample to determine the exact type of tumor, whether the tumor is benign or malignant and how serious it is (its grade).

Brain tumor grading system:

(World Health Organization grading system)
Grade I tumor	Benign = non-cancerous Slow growing Cells look almost normal under a microscope Usually associated with long-term survival Rare in adults
Grade II tumor	Relatively slow growing Sometimes spreads to nearby normal tissue and comes back (recurs) Cells look slightly abnormal under a microscope Sometimes comes back as a higher grade tumor
Grade III tumor	Malignant = cancerous Actively reproduces abnormal cells Tumor spreads into nearby normal parts of the brain Cells look abnormal under a microscope Tends to come back, often as a higher grade tumor
Grade IV tumor	Most malignant Grows fast Easily spreads into nearby normal parts of the brain Actively reproduces abnormal cells Cells look very abnormal under a microscope Tumor forms new blood vessels to maintain rapid growth Tumors have areas of dead cells in their center (called necrosis)

A changing diagnosis

The grade of a brain tumor might change. Reasons for this include:

Brain tumors sometimes change (usually to a higher grade)
The biopsy sample might not represent the entire tumor

A change from a low-grade tumor to a high-grade tumor happens more often in adults than in children.

Making the diagnosis without a biopsy

If doctors cannot perform a biopsy, they will determine a treatment plan on test results.

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Brain Tumor Center

Brain Tumor Grades: Biopsy and Prognosis

Brain tumor grading system:

A changing diagnosis

Making the diagnosis without a biopsy