Neuroscience Clerkship

GLIOMAS: WHO GRADING SCHEME

Gliomas have 4 grades by World Health Organization (WHO) from benign to progressively more malignant

● Grade I - Pilocytic

● Grade II- Low-grade

● Grade III - Anaplastic

● Grade IV - Glioblastoma multiforme

Pilocytic tumors are very benign histologically and typically occur in children.

Low-grade tumors can be slow-growing and controlled by treatment. If they recur, they usually are higher grade tumors.

Anaplastic tumors are malignant tumors with mitoses and nuclear atypia.

Glioblastoma multiforme are malignant tumors with necrosis and microvascular proliferation (figure above - gross specimen on the left; microscopic on the right).

The terms benign and malignant can be used to describe the pathologic appearance of a brain tumor, but the terms often do not convey appropriate information about the overall prognosis from a tumor. A tumor can have a benign histology but be unresectable and difficult to control with radiation or chemotherapy, and thus be a life-limiting problem. Examples of benign tumors with a possible poor prognosis are craniopharyngiomas, meningiomas, schwannomas, or hypothalamic gliomas.