CNS tumors are graded on a scale from I to IV based on their histological features:
Grade I: These tumors are generally low-grade, slow-growing, and less likely to invade surrounding tissues. Examples include pilocytic astrocytoma and subependymal giant cell astrocytoma. Grade II: These tumors are low-grade but have a higher potential for recurrence and slightly more aggressive behavior. Examples include diffuse astrocytoma and oligodendroglioma. Grade III: These are high-grade tumors with more aggressive behavior and higher recurrence rates. Examples include anaplastic astrocytoma and anaplastic oligodendroglioma. Grade IV: These are the most aggressive and malignant tumors, such as glioblastoma and medulloblastoma.
