Brain Tumor Grades: Biopsy and Prognosis

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.

To request a consultation or appointment, call 410-955-6406.