Medulloblastoma 

General
- from cells resembling immature neurons of cerebellum
- Most common malignant/high grade tumor of children - also most common posterior fossa tumor of children (30-40%)
- Mean age of appearance - 9 years. When they occur in adults (rare) typically 3rd-4th decade, better prognosis
- May recur locally or spread in CSF - drop mets in spinal cord, or explants in hemispheres.

Prognosis
- Heterogenous group of tumors - prognosis varies widely depending on molecular signaling.
- Tx: surgical resection, chemo, whole brain and spine RT to manage potential mets/prevent spread.
- 5-year survival 50-70%, but with high morbidity 2/2 RT - i.e. short stature due to hypothalamic and spinal bony RT, secondary malignancy.

Path
- small blue cell tumor - sheets of undifferentiated cells. Sometimes rosettes.

- "rosettes" 

- sheets of blue cells

Neuronal lineage - stain + with neuronal markers like synaptophysin and NeuN (nuclear marker of neurons)

Imaging:
(source: radiopaedia, this paper)
- CT bright - may have significant cystic/calcific components
- T1 dark
- 90% enhance, usually heterogenously

- medullo with leptomeningeal spread along anterior pons 

- classic medullo - emerging from cb vermis 

- leptomeningeal mets.