May arise in cerebellum, midline.

Gross Pathology: cream of wheat!

Very cellular tumour.

Disseminates through CSF.

Tumour cells going into subarachnoid surface re invading the surface of the brain.

Can get intp the ventricular system.

Drop down the spinal cord.

Small blue round cell tumour —> undifferentiated cells. Lot of mitosis. Very cellular.